Mathematical, numerical and experimental analysis of the swirling flow at a Kaplan runner outlet

NASA Astrophysics Data System (ADS)

Muntean, S.; Ciocan, T.; Susan-Resiga, R. F.; Cervantes, M.; Nilsson, H.

2012-11-01

The paper presents a novel mathematical model for a-priori computation of the swirling flow at Kaplan runners outlet. The model is an extension of the initial version developed by Susan-Resiga et al [1], to include the contributions of non-negligible radial velocity and of the variable rothalpy. Simple analytical expressions are derived for these additional data from three-dimensional numerical simulations of the Kaplan turbine. The final results, i.e. velocity components profiles, are validated against experimental data at two operating points, with the same Kaplan runner blades opening, but variable discharge.

Optimization of a GO2/GH2 Swirl Coaxial Injector Element

NASA Technical Reports Server (NTRS)

Tucker, P. Kevin; Shyy, Wei; Vaidyanathan, Rajkumar

1999-01-01

An injector optimization methodology, method i, is used to investigate optimal design points for a gaseous oxygen/gaseous hydrogen (GO2/GH2) swirl coaxial injector element. The element is optimized in terms of design variables such as fuel pressure drop, DELTA P(sub f), oxidizer pressure drop, DELTA P(sub 0) combustor length, L(sub comb), and full cone swirl angle, theta, for a given mixture ratio and chamber pressure. Dependent variables such as energy release efficiency, ERE, wall heat flux, Q(sub w) injector heat flux, Q(sub inj), relative combustor weight, W(sub rel), and relative injector cost, C(sub rel), are calculated and then correlated with the design variables. An empirical design methodology is used to generate these responses for 180 combinations of input variables. Method i is then used to generate response surfaces for each dependent variable. Desirability functions based on dependent variable constraints are created and used to facilitate development of composite response surfaces representing some, or all, of the five dependent variables in terms of the input variables. Two examples illustrating the utility and flexibility of method i are discussed in detail. First, joint response surfaces are constructed by sequentially adding dependent variables. Optimum designs are identified after addition of each variable and the effect each variable has on the design is shown. This stepwise demonstration also highlights the importance of including variables such as weight and cost early in the design process. Secondly, using the composite response surface that includes all five dependent variables, unequal weights are assigned to emphasize certain variables relative to others. Here, method i is used to enable objective trade studies on design issues such as component life and thrust to weight ratio.

Performance characteristics of LOX-H2, tangential-entry, swirl-coaxial, rocket injectors

NASA Technical Reports Server (NTRS)

Howell, Doug; Petersen, Eric; Clark, Jim

1993-01-01

Development of a high performing swirl-coaxial injector requires an understanding of fundamental performance characteristics. This paper addresses the findings of studies on cold flow atomic characterizations which provided information on the influence of fluid properties and element operating conditions on the produced droplet sprays. These findings are applied to actual rocket conditions. The performance characteristics of swirl-coaxial injection elements under multi-element hot-fire conditions were obtained by analysis of combustion performance data from three separate test series. The injection elements are described and test results are analyzed using multi-variable linear regression. A direct comparison of test results indicated that reduced fuel injection velocity improved injection element performance through improved propellant mixing.

Numerical analysis of flow interaction of turbine system in two-stage turbocharger of internal combustion engine

NASA Astrophysics Data System (ADS)

Liu, Y. B.; Zhuge, W. L.; Zhang, Y. J.; Zhang, S. Y.

2016-05-01

To reach the goal of energy conservation and emission reduction, high intake pressure is needed to meet the demand of high power density and high EGR rate for internal combustion engine. Present power density of diesel engine has reached 90KW/L and intake pressure ratio needed is over 5. Two-stage turbocharging system is an effective way to realize high compression ratio. Because turbocharging system compression work derives from exhaust gas energy. Efficiency of exhaust gas energy influenced by design and matching of turbine system is important to performance of high supercharging engine. Conventional turbine system is assembled by single-stage turbocharger turbines and turbine matching is based on turbine MAP measured on test rig. Flow between turbine system is assumed uniform and value of outlet physical quantities of turbine are regarded as the same as ambient value. However, there are three-dimension flow field distortion and outlet physical quantities value change which will influence performance of turbine system as were demonstrated by some studies. For engine equipped with two-stage turbocharging system, optimization of turbine system design will increase efficiency of exhaust gas energy and thereby increase engine power density. However flow interaction of turbine system will change flow in turbine and influence turbine performance. To recognize the interaction characteristics between high pressure turbine and low pressure turbine, flow in turbine system is modeled and simulated numerically. The calculation results suggested that static pressure field at inlet to low pressure turbine increases back pressure of high pressure turbine, however efficiency of high pressure turbine changes little; distorted velocity field at outlet to high pressure turbine results in swirl at inlet to low pressure turbine. Clockwise swirl results in large negative angle of attack at inlet to rotor which causes flow loss in turbine impeller passages and decreases turbine efficiency. However negative angle of attack decreases when inlet swirl is anti-clockwise and efficiency of low pressure turbine can be increased by 3% compared to inlet condition of clockwise swirl. Consequently flow simulation and analysis are able to aid in figuring out interaction mechanism of turbine system and optimizing turbine system design.

A multiple-time-scale turbulence model based on variable partitioning of turbulent kinetic energy spectrum

NASA Technical Reports Server (NTRS)

Kim, S.-W.; Chen, C.-P.

1988-01-01

The paper presents a multiple-time-scale turbulence model of a single point closure and a simplified split-spectrum method. Consideration is given to a class of turbulent boundary layer flows and of separated and/or swirling elliptic turbulent flows. For the separated and/or swirling turbulent flows, the present turbulence model yielded significantly improved computational results over those obtained with the standard k-epsilon turbulence model.

Effect of Premixed Fuel Preparation for Partially Premixed Combustion with a Low Octane Gasoline on a Light-Duty Multi-Cylinder Compression Ignition Engine

DOE PAGES

Dempsey, Adam B.; Curran, Scott; Wagner, Robert M.; ...

2015-05-12

Gasoline compression ignition concepts with the majority of the fuel being introduced early in the cycle are known as partially premixed combustion (PPC). Previous research on single- and multi-cylinder engines has shown that PPC has the potential for high thermal efficiency with low NOx and soot emissions. A variety of fuel injection strategies has been proposed in the literature. These injection strategies aim to create a partially stratified charge to simultaneously reduce NOx and soot emissions while maintaining some level of control over the combustion process through the fuel delivery system. The impact of the direct injection strategy to createmore » a premixed charge of fuel and air has not previously been explored, and its impact on engine efficiency and emissions is not well understood. This paper explores the effect of sweeping the direct injected pilot timing from -91° to -324° ATDC, which is just after the exhaust valve closes for the engine used in this study. During the sweep, the pilot injection consistently contained 65% of the total fuel (based on command duration ratio), and the main injection timing was adjusted slightly to maintain combustion phasing near top dead center. A modern four cylinder, 1.9 L diesel engine with a variable geometry turbocharger, high pressure common rail injection system, wide included angle injectors, and variable swirl actuation was used in this study. The pistons were modified to an open bowl configuration suitable for highly premixed combustion modes. The stock diesel injection system was unmodified, and the gasoline fuel was doped with a lubricity additive to protect the high pressure fuel pump and the injectors. The study was conducted at a fixed speed/load condition of 2000 rpm and 4.0 bar brake mean effective pressure (BMEP). The pilot injection timing sweep was conducted at different intake manifold pressures, swirl levels, and fuel injection GTP-15-1067, Dempsey 2 pressures. The gasoline used in this study has relatively high fuel reactivity with a research octane number of 68. The results of this experimental campaign indicate that the highest brake thermal efficiency and lowest emissions are achieved simultaneously with the earliest pilot injection timings (i.e., during the intake stroke).« less

Modelling of air flow supply in a room at variable regime by using both K - E and spalart - allmaras turbulent model

NASA Astrophysics Data System (ADS)

Korbut, Vadim; Voznyak, Orest; Sukholova, Iryna; Myroniuk, Khrystyna

2017-12-01

The abstract is to The article is devoted to the decision of actual task of air distribution efficiency increasing with the help of swirl and spread air jets to provide normative parameters of air in the production apartments. The mathematical model of air supply with swirl and spread air jets in that type of apartments is improved. It is shown that for reachin of air distribution maximal efficiency it is necessary to supply air by air jets, that intensively extinct before entering into a working area. Simulation of air flow performed with the help of CFD FLUENT (Ansys FLUENT). Calculations of the equation by using one-parameter model of turbulence Spalart-Allmaras are presented. The graphical and the analytical dependences on the basis of the conducted experimental researches, which can be used in subsequent engineering calculations, are shown out. Dynamic parameters of air flow that is created due to swirl and spread air jets at their leakage at variable regime and creation of dynamic microclimate in a room has been determined. Results of experimental investigations of air supply into the room by air distribution device which creates swirl air jets for creation more intensive turbulization air flow in the room are presented. Obtained results of these investigations give possibility to realize engineer calculations of air distribution with swirl air jets. The results of theoretical researches of favourable influence of dynamic microclimate to the man are presented. When using dynamic microclimate, it's possible to decrease conditioning and ventilation system expenses. Human organism reacts favourably on short lasting deviations from the rationed parameters of air environment.

Effect of Blockage and Location on Mixing of Swirling Coaxial Jets in a Non-expanding Circular Confinement

NASA Astrophysics Data System (ADS)

Patel, V. K.; Singh, S. N.; Seshadri, V.

2013-06-01

A study is conducted to evolve an effective design concept to improve mixing in a combustor chamber to reduce the amount of intake air. The geometry used is that of a gas turbine combustor model. For simplicity, both the jets have been considered as air jets and effect of heat release and chemical reaction has not been modeled. Various contraction shapes and blockage have been investigated by placing them downstream at different locations with respect to inlet to obtain better mixing. A commercial CFD code `Fluent 6.3' which is based on finite volume method has been used to solve the flow in the combustor model. Validation is done with the experimental data available in literature using standard k-ω turbulence model. The study has shown that contraction and blockage at optimum location enhances the mixing process. Further, the effect of swirl in the jets has also investigated.

Numerical simulation of the flow field and fuel sprays in an IC engine

NASA Technical Reports Server (NTRS)

Nguyen, H. L.; Schock, H. J.; Ramos, J. I.; Carpenter, M. H.; Stegeman, J. D.

1987-01-01

A two-dimensional model for axisymmetric piston-cylinder configurations is developed to study the flow field in two-stroke direct-injection Diesel engines under motored conditions. The model accounts for turbulence by a two-equation model for the turbulence kinetic energy and its rate of dissipation. A discrete droplet model is used to simulate the fuel spray, and the effects of the gas phase turbulence on the droplets is considered. It is shown that a fluctuating velocity can be added to the mean droplet velocity every time step if the step is small enough. Good agreement with experimental data is found for a range of ambient pressures in Diesel engine-type microenvironments. The effects of the intake swirl angle in the spray penetration, vaporization, and mixing in a uniflow-scavenged two-stroke Diesel engine are analyzed. It is found that the swirl increases the gas phase turbulence levels and the rates of vaporization.

A Computer Code for Swirling Turbulent Axisymmetric Recirculating Flows in Practical Isothermal Combustor Geometries

NASA Technical Reports Server (NTRS)

Lilley, D. G.; Rhode, D. L.

1982-01-01

A primitive pressure-velocity variable finite difference computer code was developed to predict swirling recirculating inert turbulent flows in axisymmetric combustors in general, and for application to a specific idealized combustion chamber with sudden or gradual expansion. The technique involves a staggered grid system for axial and radial velocities, a line relaxation procedure for efficient solution of the equations, a two-equation k-epsilon turbulence model, a stairstep boundary representation of the expansion flow, and realistic accommodation of swirl effects. A user's manual, dealing with the computational problem, showing how the mathematical basis and computational scheme may be translated into a computer program is presented. A flow chart, FORTRAN IV listing, notes about various subroutines and a user's guide are supplied as an aid to prospective users of the code.

Internal hernia after gastric bypass: sensitivity and specificity of seven CT signs with surgical correlation and controls.

PubMed

Lockhart, Mark E; Tessler, Franklin N; Canon, Cheri L; Smith, J Kevin; Larrison, Matthew C; Fineberg, Naomi S; Roy, Brandon P; Clements, Ronald H

2007-03-01

The purpose of this study was to evaluate the sensitivity and specificity of seven CT signs in the diagnosis of internal hernia after laparoscopic Roux-en-Y gastric bypass. With institutional review board approval, the CT scans of 18 patients (17 women, one man) with surgically proven internal hernia after laparoscopic Roux-en-Y gastric bypass were retrieved, as were CT studies of a control group of 18 women who had undergone gastric bypass but did not have internal hernia at reoperation. The scans were reviewed by three radiologists for the presence of seven CT signs of internal hernia: swirled appearance of mesenteric fat or vessels, mushroom shape of hernia, tubular distal mesenteric fat surrounded by bowel loops, small-bowel obstruction, clustered loops of small bowel, small bowel other than duodenum posterior to the superior mesenteric artery, and right-sided location of the distal jejunal anastomosis. Sensitivity and specificity were calculated for each sign. Stepwise logistic regression was performed to ascertain an independent set of variables predictive of the presence of internal hernia. Mesenteric swirl was the best single predictor of hernia; sensitivity was 61%, 78%, and 83%, and specificity was 94%, 89%, and 67% for the three reviewers. The combination of swirled mesentery and mushroom shape of the mesentery was better than swirled mesentery alone, sensitivity being 78%, 83%, and 83%, and specificity being 83%, 89%, and 67%, but the difference was not statistically significant. Mesenteric swirl is the best indicator of internal hernia after laparoscopic Roux-en-Y gastric bypass, and even minor degrees of swirl should be considered suspicious.

An Optimization-Based Approach to Injector Element Design

NASA Technical Reports Server (NTRS)

Tucker, P. Kevin; Shyy, Wei; Vaidyanathan, Rajkumar; Turner, Jim (Technical Monitor)

2000-01-01

An injector optimization methodology, method i, is used to investigate optimal design points for gaseous oxygen/gaseous hydrogen (GO2/GH2) injector elements. A swirl coaxial element and an unlike impinging element (a fuel-oxidizer-fuel triplet) are used to facilitate the study. The elements are optimized in terms of design variables such as fuel pressure drop, APf, oxidizer pressure drop, deltaP(sub f), combustor length, L(sub comb), and full cone swirl angle, theta, (for the swirl element) or impingement half-angle, alpha, (for the impinging element) at a given mixture ratio and chamber pressure. Dependent variables such as energy release efficiency, ERE, wall heat flux, Q(sub w), injector heat flux, Q(sub inj), relative combustor weight, W(sub rel), and relative injector cost, C(sub rel), are calculated and then correlated with the design variables. An empirical design methodology is used to generate these responses for both element types. Method i is then used to generate response surfaces for each dependent variable for both types of elements. Desirability functions based on dependent variable constraints are created and used to facilitate development of composite response surfaces representing the five dependent variables in terms of the input variables. Three examples illustrating the utility and flexibility of method i are discussed in detail for each element type. First, joint response surfaces are constructed by sequentially adding dependent variables. Optimum designs are identified after addition of each variable and the effect each variable has on the element design is illustrated. This stepwise demonstration also highlights the importance of including variables such as weight and cost early in the design process. Secondly, using the composite response surface that includes all five dependent variables, unequal weights are assigned to emphasize certain variables relative to others. Here, method i is used to enable objective trade studies on design issues such as component life and thrust to weight ratio. Finally, combining results from both elements to simulate a trade study, thrust-to-weight trends are illustrated and examined in detail.

Liquid sprays and flow studies in the direct-injection diesel engine under motored conditions

NASA Technical Reports Server (NTRS)

Nguyen, Hung Lee; Carpenter, Mark H.; Ramos, Juan I.; Schock, Harold J.; Stegeman, James D.

1988-01-01

A two dimensional, implicit finite difference method of the control volume variety, a two equation model of turbulence, and a discrete droplet model were used to study the flow field, turbulence levels, fuel penetration, vaporization, and mixing in diesel engine environments. The model was also used to study the effects of engine speed, injection angle, spray cone angle, droplet distribution, and intake swirl angle on the flow field, spray penetration and vaporization, and turbulence in motored two-stroke diesel engines. It is shown that there are optimum conditions for injection, which depend on droplet distribution, swirl, spray cone angle, and injection angle. The optimum conditions result in good spray penetration and vaporization and in good fuel mixing. The calculation presented clearly indicates that internal combustion engine models can be used to assess, at least qualitatively, the effects of injection characteristics and engine operating conditions on the flow field and on the spray penetration and vaporization in diesel engines.

Method for Determining Optimum Injector Inlet Geometry

NASA Technical Reports Server (NTRS)

Myers, W. Neill (Inventor); Trinh, Huu P. (Inventor)

2015-01-01

A method for determining the optimum inlet geometry of a liquid rocket engine swirl injector includes obtaining a throttleable level phase value, volume flow rate, chamber pressure, liquid propellant density, inlet injector pressure, desired target spray angle and desired target optimum delta pressure value between an inlet and a chamber for a plurality of engine stages. The method calculates the tangential inlet area for each throttleable stage. The method also uses correlation between the tangential inlet areas and delta pressure values to calculate the spring displacement and variable inlet geometry of a liquid rocket engine swirl injector.

The influence of fuel-air swirl intensity on flame structures of syngas swirl-stabilized diffusion flame

NASA Astrophysics Data System (ADS)

Shao, Weiwei; Xiong, Yan; Mu, Kejin; Zhang, Zhedian; Wang, Yue; Xiao, Yunhan

2010-06-01

Flame structures of a syngas swirl-stabilized diffusion flame in a model combustor were measured using the OH-PLIF method under different fuel and air swirl intensity. The flame operated under atmospheric pressure with air and a typical low heating-value syngas with a composition of 28.5% CO, 22.5% H2 and 49% N2 at a thermal power of 34 kW. Results indicate that increasing the air swirl intensity with the same fuel, swirl intensity flame structures showed little difference except a small reduction of flame length; but also, with the same air swirl intensity, fuel swirl intensity showed great influence on flame shape, length and reaction zone distribution. Therefore, compared with air swirl intensity, fuel swirl intensity appeared a key effect on the flame structure for the model combustor. Instantaneous OH-PLIF images showed that three distinct typical structures with an obvious difference of reaction zone distribution were found at low swirl intensity, while a much compacter flame structure with a single, stable and uniform reaction zone distribution was found at large fuel-air swirl intensity. It means that larger swirl intensity leads to efficient, stable combustion of the syngas diffusion flame.

Investigation of flowfields found in typical combustor geometries

NASA Technical Reports Server (NTRS)

Lilley, D. G.

1985-01-01

Activities undertaken during the entire course of research are summarized. Studies were concerned with experimental and theoretical research on 2-D axisymmetric geometries under low speed nonreacting, turbulent, swirling flow conditions typical of gas turbine and ramjet combustion chambers. They included recirculation zone characterization, time-mean and turbulence simulation in swirling recirculating flow, sudden and gradual expansion flowfields, and furher complexities and parameter influences. The study included the investigation of: a complete range of swirl strengths; swirler performance; downstream contraction nozzle sizes and locations; expansion ratios; and inlet side-wall angles. Their individual and combined effects on the test section flowfield were observed, measured and characterized. Experimental methods included flow visualization (with smoke and neutrally-buoyant helium-filled soap bubbles), five-hole pitot probe time-mean velocity field measurements, and single-, double-, and triple-wire hot-wire anemometry measurements of time-mean velocities, normal and shear Reynolds sresses. Computational methods included development of the STARPIC code from the primitive-variable TEACH computer code, and its use in flowfield prediction and turbulence model development.

Methods and Apparatus for Deployable Swirl Vanes

NASA Technical Reports Server (NTRS)

Shah, Parthiv N. (Inventor)

2017-01-01

An aircraft control structure for drag management includes a nozzle structure configured to exhaust a swirling fluid stream. A plurality of swirl vanes are positioned within the nozzle structure, and an actuation subsystem is configured to cause the plurality of swirl vanes to move from a deployed state to a non-deployed state. In the non-deployed state, the plurality of swirl vanes are substantially flush with the inner surface of the nozzle structure. In the deployed state, the plurality of swirl vanes produce the swirling fluid stream.

Development of Intake Swirl Generators for Turbo Jet Engine Testing

DTIC Science & Technology

1987-03-01

As a test object a Larxac 04 turbofan engine was chosen which is used as propulsion in the Alpha Jet aircraft . This twospool engine features a two...a__ OPI: !’fIC-TID N .18.1 DEVELOPMENT OF NAR 8WZRL GENERATORS FOR TURBO JET ENGINE TU TING by H.P. Gensmlor*, W. Meyer**, L. Fottner*** Dipl.-Ing...at the Universitit der Bundeswehr MUnchen. The test facility is designed for turbo jet engines up to an maximum thrust of 30kN and a maximum mass

M3 spectral analysis of lunar swirls and the link between optical maturation and surface hydroxyl formation at magnetic anomalies

USGS Publications Warehouse

Kramer, G.Y.; Besse, S.; Dhingra, D.; Nettles, J.; Klima, R.; Garrick-Bethell, I.; Clark, Roger N.; Combe, J.-P.; Head, J. W.; Taylor, L.A.; Pieters, C.M.; Boardman, J.; McCord, T.B.

2011-01-01

We examined the lunar swirls using data from the Moon Mineralogy Mapper (M3). The improved spectral and spatial resolution of M3 over previous spectral imaging data facilitates distinction of subtle spectral differences, and provides new information about the nature of these enigmatic features. We characterized spectral features of the swirls, interswirl regions (dark lanes), and surrounding terrain for each of three focus regions: Reiner Gamma, Gerasimovich, and Mare Ingenii. We used Principle Component Analysis to identify spectrally distinct surfaces at each focus region, and characterize the spectral features that distinguish them. We compared spectra from small, recent impact craters with the mature soils into which they penetrated to examine differences in maturation trends on- and off-swirl. Fresh, on-swirl crater spectra are higher albedo, exhibit a wider range in albedos and have well-preserved mafic absorption features compared with fresh off-swirl craters. Albedoand mafic absorptions are still evident in undisturbed, on-swirl surface soils, suggesting the maturation process is retarded. The spectral continuum is more concave compared with off-swirl spectra; a result of the limited spectral reddening being mostly constrained to wavelengths less than ∼1500 nm. Off-swirl spectra show very little reddening or change in continuum shape across the entire M3 spectral range. Off-swirl spectra are dark, have attenuated absorption features, and the narrow range in off-swirl albedos suggests off-swirl regions mature rapidly. Spectral parameter maps depicting the relative OH surface abundance for each of our three swirl focus regions were created using the depth of the hydroxyl absorption feature at 2.82 μm. For each of the studied regions, the 2.82 μm absorption feature is significantly weaker on-swirl than off-swirl, indicating the swirls are depleted in OH relative to their surroundings. The spectral characteristics of the swirls and adjacent terrains from all three focus regions support the hypothesis that the magnetic anomalies deflect solar wind ions away from the swirls and onto off-swirl surfaces. Nanophase iron (npFe0) is largely responsible for the spectral characteristics we attribute to space weathering and maturation, and is created by vaporization/deposition by micrometeorite impacts and sputtering/reduction by solar wind ions. On the swirls, the decreased proton flux slows the spectral effects of space weathering (relative to nonswirl regions) by limiting the npFe0 production mechanism almost exclusively to micrometeoroid impact vaporization/deposition. Immediately adjacent to the swirls, maturation is accelerated by the increased flux of protons deflected from the swirls.

Mixing enhancement in a scramjet combustor using fuel jet injection swirl

NASA Astrophysics Data System (ADS)

Flesberg, Sonja M.

The scramjet engine has proven to be a viable means of powering a hypersonic vehicle, especially after successful flights of the X-51 WaveRider and various Hy-SHOT test vehicles. The major challenge associated with operating a scramjet engine is the short residence time of the fuel and oxidizer in the combustor. The fuel and oxidizer have only milliseconds to mix, ignite and combust in the combustion chamber. Combustion cannot occur until the fuel and oxidizer are mixed on a molecular level. Therefore the improvement of mixing is of utmost interest since this can increase combustion efficiency. This study investigated mixing enhancement of fuel and oxidizer within the combustion chamber of a scramjet by introducing swirl to the fuel jet. The investigation was accomplished with numerical simulations using STAR-CCM+ computational fluid dynamic software. The geometry of the University of Virginia Supersonic Combustion Facility was used to model the isolator, combustor and nozzle of a scramjet engine for simulation purposes. Experimental data from previous research at the facility was used to verify the simulation model before investigating the effect of fuel jet swirl on mixing. The model used coaxial fuel jet with a swirling annular jet. Single coaxial fuel jet and dual coaxial fuel jet configurations were simulated for the investigation. The coaxial fuel jets were modelled with a swirling annular jet and non-swirling core jet. Numerical analysis showed that fuel jet swirl not only increased mixing and entrainment of the fuel with the oxidizer but the mixing occurred further upstream than without fuel jet swirl. The burning efficiency was calculated for the all the configurations. An increase in burning efficiency indicated an increase in the mixing of H2 with O2. In the case of the single fuel jet models, the maximum burning efficiency increase due to fuel injection jet swirl was 23.3%. The research also investigated the possibility that interaction between two swirling jets would produce increased mixing and to study how the distance between the two fuel injector exits would affect mixing. Three swirl patterns were investigated: 1) the first swirl pattern as viewed by an observer looking downstream had the right fuel annular jet swirling counter clockwise and the left fuel annular jet swirling clockwise, 2) the second swirl pattern as viewed by an observer looking downstream had the right fuel jet swirling clockwise and the left fuel jet swirling counter clockwise, 3) the third swirl pattern as viewed by an observer looking downstream had both the right and left fuel jet swirling in the same clockwise direction. Each one of the swirl patterns were simulated with the distances between the center points of the fuel jets modelled 3, 4, and 5 times the fuel injector radius. The swirl pattern that produced the greatest increase in burning efficiency differed according to the fuel injector spacing. The maximum increase in burning efficiency compared to the corresponding non-swirling two jet baseline case was 24.6% and was produced by the first swirl pattern with the distance between the center points of the fuel jets being 5 times the fuel injector radius. The burning efficiency for the single jet non-swirling baseline case and the first swirl pattern with the distance between the center points of the fuel jets being 5 times the fuel injector radius was 0.70 and 0.90 respectively indicating a 29% increase due to dual fuel injection swirl.

Effect of initial tangential velocity distribution on the mean evolution of a swirling turbulent free jet

NASA Technical Reports Server (NTRS)

Farokhi, S.; Taghavi, R.; Rice, E. J.

1988-01-01

An existing cold jet facility at NASA-Lewis was modified to produce swirling flows with controllable initial tangential velocity distribution. Distinctly different swirl velocity profiles were produced, and their effects on jet mixing characteristics were measured downstream of an 11.43 cm diameter convergent nozzle. It was experimentally shown that in the near field of a swirling turbulent jet, the mean velocity field strongly depends on the initial swirl profile. Two extreme tangential velocity distributions were produced. The two jets shared approximately the same initial mass flow rate of 5.9 kg/s, mass averaged axial Mach number and swirl number. Mean centerline velocity decay characteristics of the solid body rotation jet flow exhibited classical decay features of a swirling jet with S = 0.48 reported in the literature. It is concluded that the integrated swirl effect, reflected in the swirl number, is inadequate in describing the mean swirling jet behavior in the near field.

Confined Turbulent Swirling Recirculating Flow Predictions. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Abujelala, M. T.

1984-01-01

Turbulent swirling flow, the STARPIC computer code, turbulence modeling of turbulent flows, the k-xi turbulence model and extensions, turbulence parameters deduction from swirling confined flow measurements, extension of the k-xi to confined swirling recirculating flows, and general predictions for confined turbulent swirling flow are discussed.

Hysteresis and precession of a swirling jet normal to a wall.

PubMed

Shtern, V; Mi, J

2004-01-01

Interaction of a swirling jet with a no-slip surface has striking features of fundamental and practical interest. Different flow states and transitions among them occur at the same conditions in combustors, vortex tubes, and tornadoes. The jet axis can undergo precession and bending in combustors; this precession enhances large-scale mixing and reduces emissions of NOx. To explore the mechanisms of these phenomena, we address conically similar swirling jets normal to a wall. In addition to the Serrin model of tornadolike flows, a new model is developed where the flow is singularity free on the axis. New analytical and numerical solutions of the Navier-Stokes equations explain occurrence of multiple states and show that hysteresis is a common feature of wall-normal vortices or swirling jets no matter where sources of motion are located. Then we study the jet stability with the aid of a new approach accounting for deceleration and nonparallelism of the base flow. An appropriate transformation of variables reduces the stability problem for this strongly nonparallel flow to a set of ordinary differential equations. A particular flow whose stability is studied in detail is a half-line vortex normal to a rigid plane-a model of a tornado and of a swirling jet issuing from a nozzle in a combustor. Helical counter-rotating disturbances appear to be first growing as Reynolds number increases. Disturbance frequency changes its sign along the neutral curve while the wave number remains positive. Short disturbance waves propagate downstream and long waves propagate upstream. This helical instability causes bending of the vortex axis and its precession-the effects observed in technological flows and in tornadoes.

Turbulent swirling jets with excitation

NASA Technical Reports Server (NTRS)

Taghavi, Rahmat; Farokhi, Saeed

1988-01-01

An existing cold-jet facility at NASA Lewis Research Center was modified to produce swirling flows with controllable initial tangential velocity distribution. Two extreme swirl profiles, i.e., one with solid-body rotation and the other predominated by a free-vortex distribution, were produced at identical swirl number of 0.48. Mean centerline velocity decay characteristics of the solid-body rotation jet flow exhibited classical decay features of a swirling jet with S - 0.48 reported in the literature. However, the predominantly free-vortex distribution case was on the verge of vortex breakdown, a phenomenon associated with the rotating flows of significantly higher swirl numbers, i.e., S sub crit greater than or equal to 0.06. This remarkable result leads to the conclusion that the integrated swirl effect, reflected in the swirl number, is inadequate in describing the mean swirling jet behavior in the near field. The relative size (i.e., diameter) of the vortex core emerging from the nozzle and the corresponding tangential velocity distribution are also controlling factors. Excitability of swirling jets is also investigated by exciting a flow with a swirl number of 0.35 by plane acoustic waves at a constant sound pressure level and at various frequencies. It is observed that the cold swirling jet is excitable by plane waves, and that the instability waves grow about 50 percent less in peak r.m.s. amplitude and saturate further upstream compared to corresponding waves in a jet without swirl having the same axial mass flux. The preferred Strouhal number based on the mass-averaged axial velocity and nozzle exit diameter for both swirling and nonswirling flows is 0.4.

Apparatus and method for generating swirling flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haden, Robert E.; Lorentz, Donald G.

An apparatus and method for generating a swirl is disclosed that is used to induce an axi-symmetric swirling flow to an incoming flow. The disclosed subject matter induces a uniform and axi-symmetric swirl, circumferentially around a discharge location, thus imparting a more accurate, repeatable, continuous, and controllable swirl and mixing condition of interest. Moreover, the disclosed subject matter performs the swirl injection at a lower pressure drop in comparison to a more traditional methods and devices.

Numerical simulation of the effect of upstream swirling flow on swirl meter performance

NASA Astrophysics Data System (ADS)

Chen, Desheng; Cui, Baoling; Zhu, Zuchao

2018-04-01

Flow measurement is important in the fluid process and transmission system. For the need of accuracy measurement of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may produce swirling flow in the natural gas pipeline networks system and many other industry fields. In order to reveal the influence of upstream swirling flow on internal flow fields and the metrological characteristics, numerical simulations are carried out on the swirl meter. Using RNG k-ɛ turbulent model and SIMPLE algorithm, the flow field is numerically simulated under swirling flows generated from co-swirl and counter-swirl flow. Simulation results show fluctuation is enhanced or weakened depending on the rotating direction of swirling flow. A counter- swirl flow increases the entropy production rate at the inlet and outlet of the swirler, the junction region between throat and divergent section, and then the pressure loss is increased. The vortex precession dominates the static pressure distributions on the solid walls and in the channel, especially at the end region of the throat.

Lean blowout limits of a gas turbine combustor operated with aviation fuel and methane

NASA Astrophysics Data System (ADS)

Xiao, Wei; Huang, Yong

2016-05-01

Lean blowout (LBO) limits is critical to the operational performance of combustion systems in propulsion and power generation. The swirl cup plays an important role in flame stability and has been widely used in aviation engines. Therefore, the effects of swirl cup geometry and flow dynamics on LBO limits are significant. An experiment was conducted for studying the lean blowout limits of a single dome rectangular model combustor with swirl cups. Three types of swirl cup (dual-axial swirl cup, axial-radial swirl cup, dual-radial swirl cup) were employed in the experiment which was operated with aviation fuel (Jet A-1) and methane under the idle condition. Experimental results showed that, with using both Jet A-1 and methane, the LBO limits increase with the air flow of primary swirler for dual-radial swirl cup, while LBO limits decrease with the air flow of primary swirler for dual-axial swirl cup. In addition, LBO limits increase with the swirl intensity for three swirl cups. The experimental results also showed that the flow dynamics instead of atomization poses a significant influence on LBO limits. An improved semi-empirical correlation of experimental data was derived to predict the LBO limits for gas turbine combustors.

Measuring air core characteristics of a pressure-swirl atomizer via a transparent acrylic nozzle at various Reynolds numbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Eun J.; Oh, Sang Youp; Kim, Ho Y.

2010-11-15

Because of thermal fluid-property dependence, atomization stability (or flow regime) can change even at fixed operating conditions when subject to temperature change. Particularly at low temperatures, fuel's high viscosity can prevent a pressure-swirl (or simplex) atomizer from sustaining a centrifugal-driven air core within the fuel injector. During disruption of the air core inside an injector, spray characteristics outside the nozzle reflect a highly unstable, nonlinear mode where air core length, Sauter mean diameter (SMD), cone angle, and discharge coefficient variability. To better understand injector performance, these characteristics of the pressure-swirl atomizer were experimentally investigated and data were correlated to Reynoldsmore » numbers (Re). Using a transparent acrylic nozzle, the air core length, SMD, cone angle, and discharge coefficient are observed as a function of Re. The critical Reynolds numbers that distinguish the transition from unstable mode to transitional mode and eventually to a stable mode are reported. The working fluids are diesel and a kerosene-based fuel, referred to as bunker-A. (author)« less

Measurement and evaluation of swirl-type flow in labyrinth seals of conventional turbine stages

NASA Technical Reports Server (NTRS)

Hauck, L.

1982-01-01

The effects of load factor and rotor eccentricity were determined on flow conditions in test series for two stages. The results indicate that swirl-type entry flow follows the rules of potential swirl. Within the labyrinth cavities two spatial separated flow areas are considered. A dominating flow in periphera direction nearly fills the space between the sealing strips and the ceiling of the cavity. Below this flow, an area of axial mass transport is situated, with a slight peripheral component, limited on the nearest surroundings of the seals gap and the rotor surface. Between both flows, an exchange of energy takes place. Within the gaps, flow direction depends on axial velocity and therefore on variable flow contraction. A balance of energy within the seal and the cavities interprets the results of lateral force measurements as an influence of friction at the sealing strips surface and the rotating shaft surface. Stages with their blades put together in buckets by means of shrouding segments are particularly influenced by the rotating speed of the shrouding.

Characterization of Swirl-Venturi Lean Direct Injection Designs for Aviation Gas-Turbine Combustion

NASA Technical Reports Server (NTRS)

Heath, Christopher M.

2013-01-01

Injector geometry, physical mixing, chemical processes, and engine cycle conditions together govern performance, operability and emission characteristics of aviation gas-turbine combustion systems. The present investigation explores swirl-venturi lean direct injection combustor fundamentals, characterizing the influence of key geometric injector parameters on reacting flow physics and emission production trends. In this computational study, a design space exploration was performed using a parameterized swirl-venturi lean direct injector model. From the parametric geometry, 20 three-element lean direct injection combustor sectors were produced and simulated using steady-state, Reynolds-averaged Navier-Stokes reacting computations. Species concentrations were solved directly using a reduced 18-step reaction mechanism for Jet-A. Turbulence closure was obtained using a nonlinear ?-e model. Results demonstrate sensitivities of the geometric perturbations on axially averaged flow field responses. Output variables include axial velocity, turbulent kinetic energy, static temperature, fuel patternation and minor species mass fractions. Significant trends have been reduced to surrogate model approximations, intended to guide future injector design trade studies and advance aviation gas-turbine combustion research.

OIL SPILL DISPERSANT EFFECTIVENESS PROTOCOL. I: IMPACT OF OPERATIONAL VARIABLES

EPA Science Inventory

The current U.S. Environmental Protection Agency protocol for testing the effectiveness of dispersants, the swirling flask test, has been found to give widely varying results in the hands of different testing laboratories. The sources of the ambiguities in the test were determin...

A general method to determine the stability of compressible flows

NASA Technical Reports Server (NTRS)

Guenther, R. A.; Chang, I. D.

1982-01-01

Several problems were studied using two completely different approaches. The initial method was to use the standard linearized perturbation theory by finding the value of the individual small disturbance quantities based on the equations of motion. These were serially eliminated from the equations of motion to derive a single equation that governs the stability of fluid dynamic system. These equations could not be reduced unless the steady state variable depends only on one coordinate. The stability equation based on one dependent variable was found and was examined to determine the stability of a compressible swirling jet. The second method applied a Lagrangian approach to the problem. Since the equations developed were based on different assumptions, the condition of stability was compared only for the Rayleigh problem of a swirling flow, both examples reduce to the Rayleigh criterion. This technique allows including the viscous shear terms which is not possible in the first method. The same problem was then examined to see what effect shear has on stability.

Exhaust gas measurements in a propane fueled swirl stabilized combustor

NASA Technical Reports Server (NTRS)

Aanad, M. S.

1982-01-01

Exhaust gas temperature, velocity, and composition are measured and combustor efficiencies are calculated in a lean premixed swirl stabilized laboratory combustor. The radial profiles of the data between the co- and the counter swirl cases show significant differences. Co-swirl cases show evidence of poor turbulent mixing across the combustor in comparison to the counter-swirl cases. NO sub x levels are low in the combustor but substantial amounts of CO are present. Combustion efficiencies are low and surprisingly constant with varying outer swirl in contradiction to previous results under a slightly different inner swirl condition. This difference in the efficiency trends is expected to be a result of the high sensitivity of the combustor to changes in the inner swirl. Combustor operation is found to be the same for propane and methane fuels. A mechanism is proposed to explain the combustor operation and a few important characteristics determining combustor efficiency are identified.

Geomorphological Analysis of Lunar Swirls: Insights from LROC-NAC

NASA Astrophysics Data System (ADS)

Jozwiak, L. M.; Blewett, D. T.

2017-12-01

The enigmatic features known as lunar swirls are a set of high-reflectance, sinuous features observed in both mare and highland settings, and often associated with crustal magnetic anomalies. There are several hypotheses for the formation of swirls, including atypical space weathering resulting from solar wind stand-off, disruption of regolith structure and imposition of a magnetic field associated with recent cometary impacts, and levitation and magnetic sorting of fine-grained dust. Investigations utilizing data from Diviner and Mini-RF suggest that, at the scales sensed by the instruments, regolith in swirl regions is indistinguishable from regolith in non-swirl regions. We have used data from the LRO Camera-Narrow Angle Camera to study the structure of lunar swirls, and explore whether the high-reflectance material associated with lunar swirls represents a discrete deposit. We assessed the populations of impact craters with diameter greater than 1 km on the Reiner Gamma swirl and on a nearby region of lunar mare located on the same lava flow unit, and determined that the crater populations suggest that the presence of the swirl does not affect the background impact crater population. We also investigated whether small (D < 0.5 km) superposed impact craters showed evidence for excavation of material from beneath a hypothetical surficial swirl deposit. Investigating the swirls located at Reiner Gamma, Mare Ingenii, Mare Marginis, and the crater Gerasimovich and adjacent non-swirl regions, we observed high-reflectance ejecta deposits whose morphology and degradation are consistent with space weathering processes. We further observe the relative proportion of these high-reflectance excavations to be greater in the swirl regions, suggesting a qualitatively slower space weathering process in these regions. In all regions, we also observed the excavation of low-reflectance material distributed in the ejecta deposit of superposed craters with a wide range of diameters, and a wide range of distribution patterns. We also observe these dark materials in non-swirl regions, suggesting they are not unique to the swirl environment. Our investigations are consistent with the atypical space weathering hypothesis.

Experiments on the instabilities in swirling and non-swirling free jets

NASA Astrophysics Data System (ADS)

Panda, Jayanta

1990-08-01

Instabilities present in a free swirling jet in Reynolds number range from 20,000 to 60,000 and swirl number of 0.45 were studied using smoke visualization and hot wire measurements. A nonswirling jet of Reynolds number 60,000 produced from the same facility was also studied for validation of the experimental procedures and direct comparison with the swirling jet. Time-mean velocity components and turbulence intensity were surveyed using a single hot wire (nonswirling jet) and a V wire (swirling jet) probe. To enhance the understanding of these instabilities, axisymmetric and helical waves were excited in the Strouhal number range 0.75 to 1.5 (swirling jet) and 0.9 to 3.75 (nonswirling jet) by acoustic excitation.

Modern developments in shear flow control with swirl

NASA Technical Reports Server (NTRS)

Farokhi, Saeed; Taghavi, R.

1990-01-01

Passive and active control of swirling turbulent jets is experimentally investigated. Initial swirl distribution is shown to dominate the free jet evolution in the passive mode. Vortex breakdown, a manifestation of high intensity swirl, was achieved at below critical swirl number (S = 0.48) by reducing the vortex core diameter. The response of a swirling turbulent jet to single frequency, plane wave acoustic excitation was shown to depend strongly on the swirl number, excitation Strouhal number, amplitude of the excitation wave, and core turbulence in a low speed cold jet. A 10 percent reduction of the mean centerline velocity at x/D = 9.0 (and a corresponding increase in the shear layer momentum thickness) was achieved by large amplitude internal plane wave acoustic excitation. Helical instability waves of negative azimuthal wave numbers exhibit larger amplification rates than the plane waves in swirling free jets, according to hydrodynamic stability theory. Consequently, an active swirling shear layer control is proposed to include the generation of helical instability waves of arbitrary helicity and the promotion of modal interaction, through multifrequency forcing.

Axisymmetric flow of Casson fluid by a swirling cylinder

NASA Astrophysics Data System (ADS)

Javed, Muhammad Faisal; Khan, Muhammad Imran; Khan, Niaz Bahadur; Muhammad, Riaz; Rehman, Muftooh Ur; Khan, Sajjad Wali; Khan, Tufail A.

2018-06-01

The present communication aims to investigate the influence of heat generation/absorption on axisymmetric Casson liquid flow over a stretched cylinder. Flow is caused due to torsional motion of cylinder. The governing physical problem is modelled and transferred into set of coupled nonlinear ordinary differential equations. These equations are solved numerically using built-in-Shooting method. Influence of sundry variables on the swirling velocity, temperature, coefficient of skin friction and heat transfer rate are computed and analyzed in a physical manner. Magnitude of axial skin friction is enhances for larger Reynold number and magnetic parameter while local Nusselt number decays with the enhancement of Casson parameter, heat generation/absorption and magnetic parameter. Comparison with already existing results is also given in the limiting case.

Investigation of acoustic and gas dynamic characteristics of strongly swirled turbulent jets

NASA Astrophysics Data System (ADS)

Krasheninnikov, S. Yu; Maslov, VP; Mironov, AK; Toktaliev, PD

2018-03-01

Generalization of the series of experimental and numerical results for properties and characteristics of swirling jets with high swirling intensity W0>1 is considered. These jets are typically used in gas turbine aviation engines for intensification of mixing process and combustion process stabilization. Flow structures in swirling jets and in the near-field are analyzed. It is shown, that, in the main, the flow structure behind the swirling device can be determined by swirling intensity W 0 and acoustic fluctuations field formed far from the jet boundaries. Experimental measurements and numerical simulation of the noise levels of the highly swirling jet are performed using Ffowcs-Williams-Hawkins analogy. Maximum levels of noise axis are observed at angles of 50°-70° from the jet.

Confined turbulent swirling recirculating flow predictions. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Abujelala, M. T.; Lilley, D. G.

1985-01-01

The capability and the accuracy of the STARPIC computer code in predicting confined turbulent swirling recirculating flows is presented. Inlet flow boundary conditions were demonstrated to be extremely important in simulating a flowfield via numerical calculations. The degree of swirl strength and expansion ratio have strong effects on the characteristics of swirling flow. In a nonswirling flow, a large corner recirculation zone exists in the flowfield with an expansion ratio greater than one. However, as the degree of inlet swirl increases, the size of this zone decreases and a central recirculation zone appears near the inlet. Generally, the size of the central zone increased with swirl strength and expansion ratio. Neither the standard k-epsilon turbulence mode nor its previous extensions show effective capability for predicting confined turbulent swirling recirculating flows. However, either reduced optimum values of three parameters in the mode or the empirical C sub mu formulation obtained via careful analysis of available turbulence measurements, can provide more acceptable accuracy in the prediction of these swirling flows.

Investigation on combustion characteristics and NO formation of methane with swirling and non-swirling high temperature air

NASA Astrophysics Data System (ADS)

Li, Xing; Jia, Li

2014-10-01

Combustion characteristics of methane jet flames in an industrial burner working in high temperature combustion regime were investigated experimentally and numerically to clarify the effects of swirling high temperature air on combustion. Speziale-Sarkar-Gatski (SSG) Reynolds stress model, Eddy-Dissipation Model (EDM), Discrete Ordinates Method (DTM) combined with Weighted-Sum-of-Grey Gases Model (WSGG) were employed for the numerical simulation. Both Thermal-NO and Prompt-NO mechanism were considered to evaluate the NO formation. Temperature distribution, NO emissions by experiment and computation in swirling and non-swirling patterns show combustion characteristics of methane jet flames are totally different. Non-swirling high temperature air made high NO formation while significant NO prohibition were achieved by swirling high temperature air. Furthermore, velocity fields, dimensionless major species mole fraction distributions and Thermal-NO molar reaction rate profiles by computation interpret an inner exhaust gas recirculation formed in the combustion zone in swirling case.

Effect of TurboSwirl Structure on an Uphill Teeming Ingot Casting Process

NASA Astrophysics Data System (ADS)

Bai, Haitong; Ersson, Mikael; Jönsson, Pär

2015-12-01

To produce high-quality ingot cast steel with a better surface quality, it would be beneficial for the uphill teeming process if a much more stable flow pattern could be achieved in the runners. Several techniques have been utilized in the industry to try to obtain a stable flow of liquid steel, such as a swirling flow. Some research has indicated that a swirl blade inserted in the horizontal and vertical runners, or some other additional devices and physics could generate a swirling flow in order to give a lower hump height, avoid mold flux entrapment, and improve the quality of the ingot products, and a new swirling flow generation component, TurboSwirl, was introduced to improve the flow pattern. It has recently been demonstrated that the TurboSwirl method can effectively reduce the risk of mold flux entrapment, lower the maximum wall shear stress, and decrease velocity fluctuations. The TurboSwirl is built at the elbow of the runners as a connection between the horizontal and vertical runners. It is located near the mold and it generates a tangential flow that can be used with a divergent nozzle in order to decrease the axial velocity of the vertical flow into the mold. This stabilizes flow before the fluid enters the mold. However, high wall shear stresses develop at the walls due to the fierce rotation in the TurboSwirl. In order to achieve a calmer flow and to protect the refractory wall, some structural improvements have been made. It was found that by changing the flaring angle of the divergent nozzle, it was possible to lower the axial velocity and wall shear stress. Moreover, when the vertical runner and the divergent nozzle were not placed at the center of the TurboSwirl, quite different flow patterns could be obtained to meet to different requirements. In addition, the swirl numbers of all the cases mentioned above were calculated to ensure that the swirling flow was strong enough to generate a swirling flow of the liquid steel in the TurboSwirl.

Exhaust gas emissions of a vortex breakdown stabilized combustor

NASA Technical Reports Server (NTRS)

Yetter, R. A.; Gouldin, F. C.

1976-01-01

Exhaust gas emission data are described for a swirl stabilized continuous combustor. The combustor consists of confined concentric jets with premixed fuel and air in the inner jet and air in the outer jet. Swirl may be induced in both inner and outer jets with the sense of rotation in the same or opposite directions (co-swirl and counter-swirl). The combustor limits NO emissions by lean operation without sacrificing CO and unburned hydrocarbon emission performance, when commercial-grade methane and air fired at one atmosphere without preheat are used. Relative swirl direction and magnitude are found to have significant effects on exhaust gas concentrations, exit temperatures, and combustor efficiencies. Counter-swirl gives a large recirculation zone, a short luminous combustion zone, and large slip velocities in the interjet shear layer. For maximum counter-swirl conditions, the efficiency is low.

Numerical study of effect of compressor swirling flow on combustor design in a MTE

NASA Astrophysics Data System (ADS)

Mu, Yong; Wang, Chengdong; Liu, Cunxi; Liu, Fuqiang; Hu, Chunyan; Xu, Gang; Zhu, Junqiang

2017-08-01

An effect of the swirling flow on the combustion performance is studied by the computational fluid dynamics (CFD) in a micro-gas turbine with a centrifugal compressor, dump diffuser and forward-flow combustor. The distributions of air mass and the Temperature Pattern Factor (as: Overall Temperature Distribution Factor -OTDF) in outlet are investigated with two different swirling angles of compressed air as 0° and 15° in three combustors. The results show that the influences of swirling flow on the air distribution and OTDF cannot be neglected. Compared with no-swirling flow, the air through outer liner is more, and the air through the inner liner is less, and the pressure loss is bigger under the swirling condition in the same combustor. The Temperature Pattern Factor changes under the different swirling conditions.

Experimental and numerical investigation on the ignition and combustion stability in solid fuel ramjet with swirling flow

NASA Astrophysics Data System (ADS)

Musa, Omer; Xiong, Chen; Changsheng, Zhou

2017-08-01

The present article investigates experimentally and numerically the ignition and flame stability of high-density polyethylene solid fuel with incoming swirling air through a solid fuel ramjet (SFRJ). A new design of swirler is proposed and used in this work. Experiments on connected pipes test facility were performed for SFRJ with and without swirl. An in-house code has been developed to simulate unsteady, turbulent, reacting, swirling flow in the SFRJ. Four different swirl intensities are utilized to study experimentally and numerically the effect of swirl number on the transient regression, ignition of the solid fuel in a hot-oxidizing flow and combustion phenomenon in the SFRJ. The results showed that using swirl flow decreases the ignition time delay, recirculation zone length, and the distance between the flame and the wall, meanwhile, increases the residence time, heat transfer, regression rate and mixing degree, thus, improving the combustion efficiency and stability.

Analytical and experimental investigation of flow fields of annular jets with and without swirling flow

NASA Technical Reports Server (NTRS)

Simonson, M. R.; Smith, E. G.; Uhl, W. R.

1974-01-01

Analytical and experimental studies were performed to define the flowfield of annular jets, with and, without swirling flow. The analytical model treated configurations with variations of flow angularities, radius ratio, and swirl distributions. Swirl distributions characteristic of stator vanes and rotor blade rows, where the total pressure and swirl distributions are related were incorporated in the mathematical model. The experimental studies included tests of eleven nozzle models, both with and, without swirling exhaust flow. Flowfield surveys were obtained and used for comparison with the analytical model. This comparison of experimental and analytical studies served as the basis for evaluation of several empirical constants as required for application of the analysis to the general flow configuration. The analytical model developed during these studies is applicable to the evaluation of the flowfield and overall performance of the exhaust of statorless lift fan systems that contain various levels of exhaust swirl.

Gas turbine premixer with internal cooling

DOEpatents

York, William David; Johnson, Thomas Edward; Lacy, Benjamin Paul; Stevenson, Christian Xavier

2012-12-18

A system that includes a turbine fuel nozzle comprising an air-fuel premixer. The air-fuel premixed includes a swirl vane configured to swirl fuel and air in a downstream direction, wherein the swirl vane comprises an internal coolant path from a downstream end portion in an upstream direction through a substantial length of the swirl vane.

A Study on Rotordynamic Characteristics of Swirl Brakes for Three Types of Seals

NASA Astrophysics Data System (ADS)

Xu, Wanjun; Yang, Jiangang

2017-03-01

In order to understand swirl brakes mechanisms and their influence on rotordynamic characteristics for different types of seals, a three-dimensional flow numerical simulation was presented. Three typical seals including labyrinth seal, fully partitioned damper seal and hole-pattern seal were compared under three inlet conditions of no preswirl, preswirl and preswirl with swirl brakes. FAN boundary condition was used to provide inlet preswirl. A modified identification method of effective damping was proposed. Feasibility of the swirl brakes on improving performance of damper seals was discussed. The results show that the swirl brakes influence the seal stability characteristics with whirl frequency. For the labyrinth seal the swirl brakes reverse the sign of effective damping at low frequency and improve the seal stability performance in a wide frequency range. The swirl brakes also improve the damper seals’ stability performance by increasing the low frequency effective damping and reducing their crossover frequency. Further results indicate the swirl brakes affect the rotational direction of the maximum (minimum) pressure positions and enhance the stability of the seals by reducing tangential force in each cavity.

The Model Analysis of Inclusion Moving in the Swirl Flow Zone Sourcing from the Inner-Swirl-Type Turbulence Controller in Tundish

NASA Astrophysics Data System (ADS)

Jin, Yan; Ye, Chen; Luo, Xiao; Yuan, Hui; Cheng, Changgui

2017-05-01

In order to improve the inclusion removal property of the tundish, the mathematic model for simulation of the flow field sourced from inner-swirl-type turbulence controller (ISTTC) was developed, in which there were six blades arranged with an eccentric angle (θ) counterclockwise. Based on the mathematical and water model, the effect of inclusion removal in the swirling flow field formed by ISTTC was analyzed. It was found that ISTTC had got the better effect of inhibiting turbulence in tundish than traditional turbulence inhibitor (TI). As the blades eccentric angle (θ) of ISTTC increasing, the intensity of swirling flow above it increased. The maximum rotate speed of fluid in swirling flow band driven by ISTTC (θ=45°) was equal to 25 rmp. Based on the force analysis of inclusion in swirling flow sourced from ISTTC, the removal effect of medium size inclusion by ISTTC was attributed to the centripetal force (Fct) of swirling flow, but removal effect of ISTTC to small size inclusion was more depend on its better turbulence depression behavior.

Design and verification of a turbofan swirl augmentor

NASA Technical Reports Server (NTRS)

Egan, W. J., Jr.; Shadowen, J. H.

1978-01-01

The paper discusses the details of the design and verification testing of a full-scale turbofan 'swirl' augmentor at sea level and altitude. No flameholders are required in the swirl augmentor since the radial motion of the hot pilot gases and subsequent combustion products provides a continuous ignition front across the stream. Results of rig testing of this full-scale swirl augmentor on an F100 engine, which are very encouraging, and future development plans are presented. The results validate the application of the centrifugal-force swirling flow concept to a turbofan augmentor.

Modeling of atomization and distribution of drop-liquid fuel in unsteady swirling flows in a combustion chamber and free space

NASA Astrophysics Data System (ADS)

Sviridenkov, A. A.; Toktaliev, P. D.; Tretyakov, V. V.

2018-03-01

Numerical and experimental research of atomization and propagation of drop-liquid phase in swirling flow behind the frontal device of combustion chamber was performed. Numerical procedure was based on steady and unsteady Reynolds equations solution. It's shown that better agreement with experimental data could be obtained with unsteady approach. Fractional time step method was implemented to solve Reynolds equations. Models of primary and secondary breakup of liquid fuel jet in swirling flows are formulated and tested. Typical mean sizes of fuel droplets for base operational regime of swirling device and combustion chamber were calculated. Comparison of main features of internal swirling flow in combustion chamber with unbounded swirling flow was made.

Effect of operation parameters on the slagging near swirl coal burner throat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Changfu You; Yong Zhou

2006-10-15

Fluid flow, heat transfer, coal combustion, and slagging processes had been numerically simulated near a swirl burner throat. The effect of the ratio distribution of each burner air, their swirling numbers, and the coal character on the slagging process had been analyzed. The computation results indicate that the maximal sticking-particle numbers occur at the uppermost waterwall, while the sticking-particle number at neither waterwall near the swirl burner outlet is very small. The swirling number has a significant effect on the number of the sticking particle. The sticking-particle number increases rapidly with the increment of the outer secondary air and themore » primary air-swirling numbers, respectively, because it can strengthen the flow entrainment ability to carry more particles to the waterwall. The inner secondary air has a complicated influence on the slagging process. When the inner secondary air-swirling number is about middle intensive degree (about 0.9), the sticking-particle number reaches maximum. If the inner secondary air-swirling number continues increasing, then the coal particles will combust completely and reduce the particle concentration, thus decrease the sticking-particle number. The ratio of each air has a slight influence on the sticking-particle number relative to the swirling number. The coal particles with small mean diameter combust completely, which can reduce the sticking-particle number. 13 refs., 16 figs., 1 tab.« less

On the failure of the quasicylindrical approximation and the connection to vortex breakdown in turbulent swirling flow

NASA Astrophysics Data System (ADS)

Gyllenram, W.; Nilsson, H.; Davidson, L.

2007-04-01

This paper analyzes the properties of viscous swirling flow in a pipe. The analysis is based on the time-averaged quasicylindrical Navier-Stokes equations and is applicable to steady, unsteady, and turbulent swirling flow. A method is developed to determine the critical level of swirl (vortex breakdown) for an arbitrary vortex. The method can also be used for an estimation of the radial velocity profile if the other components are given or measured along a single radial line. The quasicylindrical equations are rearranged to yield a single ordinary differential equation for the radial distribution of the radial velocity component. The equation is singular for certain levels of swirl. It is shown that the lowest swirl level at which the equation is singular corresponds exactly to the sufficient condition for axisymmetric vortex breakdown as derived by Wang and Rusak [J. Fluid Mech. 340, 177 (1997)] and Rusak et al. [AIAA J. 36, 1848 (1998)]. In narrow regions around the critical levels of swirl, the solution violates the quasicylindrical assumptions and the flow must undergo a drastic change of structure. The critical swirl level is determined by the sign change of the smallest eigenvalue of the discrete linear operator which relates the radial velocities to effects of viscosity and turbulence. It is shown that neither viscosity nor turbulence directly alters the critical level of swirl.

Flame Structure and Emissions of Strongly-Pulsed Turbulent Diffusion Flames with Swirl

NASA Astrophysics Data System (ADS)

Liao, Ying-Hao

This work studies the turbulent flame structure, the reaction-zone structure and the exhaust emissions of strongly-pulsed, non-premixed flames with co-flow swirl. The fuel injection is controlled by strongly-pulsing the fuel flow by a fast-response solenoid valve such that the fuel flow is completely shut off between pulses. This control strategy allows the fuel injection to be controlled over a wide range of operating conditions, allowing the flame structure to range from isolated fully-modulated puffs to interacting puffs to steady flames. The swirl level is controlled by varying the ratio of the volumetric flow rate of the tangential air to that of the axial air. For strongly-pulsed flames, both with and without swirl, the flame geometry is strongly impacted by the injection time. Flames appear to exhibit compact, puff-like structures for short injection times, while elongated flames, similar in behaviors to steady flames, occur for long injection times. The flames with swirl are found to be shorter for the same fuel injection conditions. The separation/interaction level between flame puffs in these flames is essentially governed by the jet-off time. The separation between flame puffs decreases as swirl is imposed, consistent with the decrease in flame puff celerity due to swirl. The decreased flame length and flame puff celerity are consistent with an increased rate of air entrainment due to swirl. The highest levels of CO emissions are generally found for compact, isolated flame puffs, consistent with the rapid quenching due to rapid dilution with excess air. The imposition of swirl generally results in a decrease in CO levels, suggesting more rapid and complete fuel/air mixing by imposing swirl in the co-flow stream. The levels of NO emissions for most cases are generally below the steady-flame value. The NO levels become comparable to the steady-flame value for sufficiently short jet-off time. The swirled co-flow air can, in some cases, increase the NO emissions. The elevated NO emissions are due to a longer combustion residence time due to the flow recirculation within the swirl-induced recirculation zone. The reaction zone structure, based on OH planar laser-induced fluorescence (PLIF) is broadly consistent with the observation of luminous flame structure for these types of flames. In many cases, the reaction zone exhibits discontinuities at the instantaneous flame tip in the early period of fuel injection. These discontinuities in the reaction zone likely result from the non-ignition of injected fuel, due to a relatively slower reaction rate in comparison with the mixing rate. The discontinuity in the OH zone is generally seen to diminish with increased swirl level. Statistics generated from the OH PLIF signals show that the reaction zone area generally increases with increased swirl level, consistent with a broader and more convoluted OH-zone structure for flames with swirl. The reaction zone area for swirled flames generally exhibits a higher degree of fluctuation, suggesting a relatively stronger impact of flow turbulence on the flame structure for flames with swirl.

An experimental investigation of mixing enhancement in a simulated scramjet combustor by use of swirling jets. M.S. Thesis

NASA Technical Reports Server (NTRS)

Kraus, Donna Karen

1993-01-01

It is desired to maintain supersonic flow through the combustor of supersonic airbreathing engines to reduce static temperatures and total pressure losses inherent in reducing flow to subsonic speeds. Due to the supersonic speeds through the combustor, mixing of the fuel and air must by rapid for complete combustion to occur within a reasonable streamwise distance. It was proposed that the addition of swirl to the fuel jet prior to injection might enhance the mixing of the fuel with the air. The effects of swirl on the mixing of a 30 deg wall jet into a Mach 2 flow were experimentally investigated. Swirl was introduced into the fuel stream by tangential injection into a cylindrical swirl chamber. The flow was then accelerated through a convergent-divergent nozzle with an area ratio of two, and supersonically injected into the Mach 2 flow such that the static pressure of the fuel matched the effective back pressure of the main flow. Two different cases with swirl and one without swirl were investigated, with both helium and air simulating the fuel. Rayleigh scattering was used to visualize the flow and seeding the fuel with water allowed it to be traced through the main flow. Using histograms of the pure molecular Rayleigh scattering images, the helium concentration in the jet-mixing region of the flow was monitored and found to decrease slightly with swirl, indicating better mixing. Thresholding the water-seeded images allowed the jet-mixing region to be isolated and showed a slight increase in this area with swirl. Penetration, however, was slightly less with swirl. Rescaling the data for equal mass flow rates allowed comparison for a scramjet application of a combustor with a single injector and the desire to fuel to a specified fuel-to-oxidant ratio. These results showed a substantial increase in the spreading area with swirl, an increase in the mixing occurring in this area, and slightly better penetration.

Study of the heat-transfer crisis on heat-release surfaces of annular channels with swirl and transit flows

NASA Astrophysics Data System (ADS)

Boltenko, E. A.

2016-10-01

The results of the experimental study of the heat-transfer crisis on heat-release surfaces of annular channels with swirl and transit flow are presented. The experiments were carried out using electric heated annular channels with one and (or) two heat-release surfaces. For the organization of transit flow on a convex heat-release surface, four longitudinal ribs were installed uniformly at its perimeter. Swirl flow was realized using a capillary wound tightly (without gaps) on the ribs. The ratio between swirl and transit flows in the annular gap was varied by applying longitudinal ribs of different height. The experiments were carried out using a closed-type circulatory system. The experimental data were obtained in a wide range of regime parameters. Both water heated to the temperature less than the saturation temperature and water-steam mixture were fed at the inlet of the channels. For the measurement of the temperature of the heat-release surfaces, chromel-copel thermocouples were used. It was shown that the presence of swirl flow on a convex heatrelease surface led to a significant decrease in critical heat flows (CHF) compared to a smooth surface. To increase CHF, it was proposed to use the interaction of swirl flows of the heat carrier. The second swirl flow was transit flow, i.e., swirl flow with the step equal to infinity. It was shown that CHF values for a channel with swirl and transit flow in all the studied range of regime parameters was higher than CHF values for both a smooth annular channel and a channel with swirl. The empirical ratios describing the dependence of CHF on convex and concave heat-release surfaces of annular channels with swirl and transit flow on the geometrical characteristics of channels and the regime parameters were obtained. The experiments were carried out at the pressure p = 3.0-16.0 MPa and the mass velocity ρw = 250-3000 kg/(m2s).

An Experimental Study of Swirling Flows as Applied to Annular Combustors

NASA Technical Reports Server (NTRS)

Seal, Michael Damian, II

1997-01-01

This thesis presents an experimental study of swirling flows with direct applications to gas turbine combustors. Two separate flowfields were investigated: a round, swirling jet and a non-combusting annular combustor model. These studies were intended to allow both a further understanding of the behavior of general swirling flow characteristics, such as the recirculation zone, as well as to provide a base for the development of computational models. In order to determine the characteristics of swirling flows the concentration fields of a round, swirling jet were analyzed for varying amount of swirl. The experimental method used was a light scattering concentration measurement technique known as marker nephelometry. Results indicated the formation of a zone of recirculating fluid for swirl ratios (rotational speed x jet radius over mass average axial velocity) above a certain critical value. The size of this recirculation zone, as well as the spread angle of the jet, was found to increase with increase in the amount of applied swirl. The annular combustor model flowfield simulated the cold-flow characteristics of typical current annular combustors: swirl, recirculation, primary air cross jets and high levels of turbulence. The measurements in the combustor model made by the Laser Doppler Velocimetry technique, allowed the evaluation of the mean and rms velocities in the three coordinate directions, one Reynold's shear stress component and the turbulence kinetic energy: The primary cross jets were found to have a very strong effect on both the mean and turbulence flowfields. These cross jets, along with a large step change in area and wall jet inlet flow pattern, reduced the overall swirl in the test section to negligible levels. The formation of the strong recirculation zone is due mainly to the cross jets and the large step change in area. The cross jets were also found to drive a four-celled vortex-type motion (parallel to the combustor longitudinal axis) near the cross jet injection plane.

Experimental and numerical analysis of natural bio and syngas swirl flames in a model gas turbine combustor

NASA Astrophysics Data System (ADS)

Iqbal, S.; Benim, A. C.; Fischer, S.; Joos, F.; Kluβ, D.; Wiedermann, A.

2016-10-01

Turbulent reacting flows in a generic swirl gas turbine combustor model are investigated both numerically and experimentally. In the investigation, an emphasis is placed upon the external flue gas recirculation, which is a promising technology for increasing the efficiency of the carbon capture and storage process, which, however, can change the combustion behaviour significantly. A further emphasis is placed upon the investigation of alternative fuels such as biogas and syngas in comparison to the conventional natural gas. Flames are also investigated numerically using the open source CFD software OpenFOAM. In the numerical simulations, a laminar flamelet model based on mixture fraction and reaction progress variable is adopted. As turbulence model, the SST model is used within a URANS concept. Computational results are compared with the experimental data, where a fair agreement is observed.

Performance and Pollution Measurements of Two-Row Swirl-Can Combustor Having 72 Modules

NASA Technical Reports Server (NTRS)

Biaglow, James A.; Trout, Arthur M.

1975-01-01

A test program was conducted to evaluate the performance and gaseous-pollutant levels of an experimental full-annulus 72-module swirl-can combustor. A comparison of data with those for a 120-module swirl-can combustor showed no significant difference in performance or levels of gaseous pollutants. Oxides of nitrogen were correlated for the 72- and 120-swirl-can combustors by using a previously developed parameter.

Control of the Development of Swirling Airflow Dynamics and Its Impact on Biomass Combustion Characteristics

NASA Astrophysics Data System (ADS)

Barmina, I.; Valdmanis, R.; Zaķe, M.

2017-06-01

The development of the swirling flame flow field and gasification/ combustion dynamics at thermo-chemical conversion of biomass pellets has experimentally been studied using a pilot device, which combines a biomass gasifier and combustor by varying the inlet conditions of the fuel-air mixture into the combustor. Experimental modelling of the formation of the cold nonreacting swirling airflow field above the inlet nozzle of the combustor and the upstream flow formation below the inlet nozzle has been carried out to assess the influence of the inlet nozzle diameter, as well primary and secondary air supply rates on the upstream flow formation and air swirl intensity, which is highly responsible for the formation of fuel-air mixture entering the combustor and the development of combustion dynamics downstream of the combustor. The research results demonstrate that at equal primary axial and secondary swirling air supply into the device a decrease in the inlet nozzle diameter enhances the upstream air swirl formation by increasing swirl intensity below the inlet nozzle of the combustor. This leads to the enhanced mixing of the combustible volatiles with the air swirl below the inlet nozzle of the combustor providing a more complete combustion of volatiles and an increase in the heat output of the device.

Turbulent axisymmetric swirling wake: equilibrium similarity solution and experiments with a wind turbine as wake generator

NASA Astrophysics Data System (ADS)

Wosnik, Martin; Dufresne, Nathaniel

2013-11-01

An analytical and experimental investigation of the turbulent axisymmetric swirling wake was carried out. An equilibrium similarity theory was derived that obtained scaling functions from conditions for similarity from the equations of motion, leading to a new scaling function for the decay of the swirling velocity component. Axial and azimuthal (swirl) velocity fields were measured in the wake of a single 3-bladed model wind turbine with rotor diameter of 0.91 m, up to 20 diameters downstream, using X-wire constant temperature hot-wire anemometry. The turbine was positioned in the free stream, near the entrance of the UNH Flow Physics Facility, which has a test section of 6m × 2.7m cross section and 72m length. Measurements were conducted at different rotor loading conditions with blade tip-speed ratios up to 2.8. At U∞ = 7 m/s, the Reynolds number based on turbine diameter was approximately 5 ×105 . Both mean velocity deficit and mean swirl were found to persist beyond 20 diameters downstream. First evidence for a new scaling function for the mean swirl, Wmax ~Uo3 / 2 ~x-1 was found. The similarity solution thus predicts that in the axisymmetric swirling wake mean swirl decays faster with x-1 than mean velocity deficit with x - 2 / 3.

The Effect of Flow Curvature on the Axisymmetric Wake

NASA Astrophysics Data System (ADS)

Holmes, Marlin; Naughton, Jonathan

2016-11-01

The swirling turbulent wake is a perturbation to the canonical axisymmetric turbulent wake. Past studies of the axisymmetric turbulent wake have increased understanding of wake Reynolds number influence on wake characteristics such as centerline wake velocity deficit and wake width. In comparison, the axisymmetric turbulent swirling wake has received little attention. Earlier work by our group has shown that the addition of swirl can change the characteristics of the wake. The goal of this current work is to examine how wake mean flow quantities are related to the wake Reynolds number and the swirl number, where the latter quantity is the ratio of the angular momentum flux to the axial momentum deficit flux. A custom designed swirling wake generator is used in a low turbulence intensity wind tunnel flow to study the turbulent swirling wake in isolation. Stereoscopic Particle Image Velocimetry is used to obtain three component velocity fields in the axial-radial plane. From this data, the wake Reynolds number, the swirl number, centerline velocity decay, wake width, and other relevant wake mean flow quantities are determined. Using these results, the impact of swirl on wake development is discussed. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award # DE-SC0012671.

Structure of a swirling jet with vortex breakdown and combustion

NASA Astrophysics Data System (ADS)

Sharaborin, D. K.; Dulin, V. M.; Markovich, D. M.

2018-03-01

An experimental investigation is performed in order to compare the time-averaged spatial structure of low- and high-swirl turbulent premixed lean flames by using the particle image velocimetry and spontaneous Raman scattering techniques. Distributions of the time-average velocity, density and concentration of the main components of the gas mixture are measured for turbulent premixed swirling propane/air flames at atmospheric pressure for the equivalence ratio Φ = 0.7 and Reynolds number Re = 5000 for low- and high-swirl reacting jets. For the low-swirl jet (S = 0.41), the local minimum of the axial mean velocity is observed within the jet center. The positive value of the mean axial velocity indicates the absence of a permanent recirculation zone, and no clear vortex breakdown could be determined from the average velocity field. For the high-swirl jet (S = 1.0), a pronounced vortex breakdown took place with a bubble-type central recirculation zone. In both cases, the flames are stabilized in the inner mixing layer of the jet around the central wake, containing hot combustion products. O2 and CO2 concentrations in the wake of the low-swirl jet are found to be approximately two times smaller and greater than those in the recirculation zone of the high-swirl jet, respectively.

Measurements of non-reacting and reacting flow fields of a liquid swirl flame burner

NASA Astrophysics Data System (ADS)

Chong, Cheng Tung; Hochgreb, Simone

2015-03-01

The understanding of the liquid fuel spray and flow field characteristics inside a combustor is crucial for designing a fuel efficient and low emission device. Characterisation of the flow field of a model gas turbine liquid swirl burner is performed by using a 2-D particle imaging velocimetry(PIV) system. The flow field pattern of an axial flow burner with a fixed swirl intensity is compared under confined and unconfined conditions, i.e., with and without the combustor wall. The effect of temperature on the main swirling air flow is investigated under open and non-reacting conditions. The result shows that axial and radial velocities increase as a result of decreased flow density and increased flow volume. The flow field of the main swirling flow with liquid fuel spray injection is compared to non-spray swirling flow. Introduction of liquid fuel spray changes the swirl air flow field at the burner outlet, where the radial velocity components increase for both open and confined environment. Under reacting condition, the enclosure generates a corner recirculation zone that intensifies the strength of radial velocity. The reverse flow and corner recirculation zone assists in stabilizing the flame by preheating the reactants. The flow field data can be used as validation target for swirl combustion modelling.

Experimental investigation on the effects of swirling flow on augmentor performance

NASA Astrophysics Data System (ADS)

Tan, Haoyuan; Huang, Xianjian

1991-06-01

This paper describes an investigation on the effect of centrifugal force distributions on swirl augmentor performance. The experiments were conducted on the flow drag, temperature-distribution efficiency in the swirl augmentor model with different tangential velocity profiles. Four tangential velocity distributions considered are the Rankine vortex, forced vortex, free vortex, and the constant-angle vortex. The results show that the flow drag of the Rankine vortex swirler is the smallest one, and, in a swirl augmentor where flame is stabilized by using centrifugal force, the combustion efficiency can reach 90 percent or over, though the swirl number is low (S = 0.25).

Swirl effect on flow structure and mixing in a turbulent jet

NASA Astrophysics Data System (ADS)

Kravtsov, Z. D.; Sharaborin, D. K.; Dulin, V. M.

2018-03-01

The paper reports on experimental study of turbulent transport in the initial region of swirling turbulent jets. The particle image velocimetry and planar laser-induced fluorescence techniques are used to investigate the flow structure and passive scalar concentration, respectively, in free air jet with acetone vapor. Three flow cases are considered, viz., non-swirling jets and swirling jets with and without vortex breakdown and central recirculation zone. Without vortex breakdown, the swirl is shown to promote jet mixing with surrounding air and to decrease the jet core length. The vortex core breakdown further enhances mixing as the jet core disintegrates at the nozzle exit.

Flame monitoring of a model swirl injector using 1D tunable diode laser absorption spectroscopy tomography

NASA Astrophysics Data System (ADS)

Liu, Chang; Cao, Zhang; Li, Fangyan; Lin, Yuzhen; Xu, Lijun

2017-05-01

Distributions of temperature and H2O concentration in a swirling flame are critical to evaluate the performance of a gas turbine combustor. In this paper, 1D tunable diode laser absorption spectroscopy tomography (1D-TDLAST) was introduced to monitor swirling flames generated from a model swirl injector by simultaneously reconstructing the rotationally symmetric distributions of temperature and H2O concentration. The optical system was sufficiently simplified by introducing only one fan-beam illumination and a linear detector array of 12 equally-spaced photodetectors. The fan-beam illumination penetrated a cross section of interest in the swirling flame and the transmitted intensities were detected by the detector array. With the transmitted intensities in hand, projections were extracted and employed by a 1D tomographic algorithm to reconstruct the distributions of temperature and H2O concentration. The route of the precessing vortex core generated in the swirling flame can be easily inferred from the reconstructed profiles of temperature and H2O concentration at different heights above the nozzle of the swirl injector.

The acoustic Green's function for swirling flow with variable entropy in a lined duct

NASA Astrophysics Data System (ADS)

Mathews, J. R.; Peake, N.

2018-04-01

This paper extends previous work by the authors (Journal of Sound and Vibration, 395:294-316,2017) on the acoustic field inside an annular duct with acoustic lining carrying mean axial and swirling flow so as to allow for non-uniform mean entropy, as would be found for instance in the turbine stage of an aeroengine. The main aim of this paper is to understand the effect of a non-uniform entropy on both the eigenmodes of the flow and the Green's function, which will allow noise prediction once we have identified acoustic sources. We first derive a new acoustic analogy in isentropic swirling flow, which allows us to derive the equation the tailored Green's function satisfies. The eigenmodes are split into two distinct families, acoustic and hydrodynamic modes, and are computed using different analytical methods; in the limit of high reduced frequency using the WKB method for the acoustic modes; and by considering a Frobenius expansion for the hydrodynamic modes. These are then compared with numerical results, with excellent agreement for all eigenmodes. The Green's function is also calculating analytically using the realistic limit of high reduced frequency, again with excellent agreement compared to numerical calculations. We see that for both the eigenmodes and Green's function the effect of non-uniform mean entropy is significant.

Characterization of Flow Bench Engine Testing

NASA Astrophysics Data System (ADS)

Voris, Alex; Riley, Lauren; Puzinauskas, Paul

2015-11-01

This project was an attempt at characterizing particle image velocimetry (PIV) and swirl-meter test procedures. The flow direction and PIV seeding were evaluated for in-cylinder steady state flow of a spark ignition engine. For PIV seeding, both wet and dry options were tested. The dry particles tested were baby powder, glass particulate, and titanium dioxide. The wet particles tested were fogs created with olive oil, vegetable oil, DEHS, and silicon oil. The seeding was evaluated at 0.1 and 0.25 Lift/Diameter and at cylinder pressures of 10, 25 and 40 inches of H2O. PIV results were evaluated through visual and fluid momentum comparisons. Seeding particles were also evaluated based on particle size and cost. It was found that baby powder and glass particulate were the most effective seeding options for the current setup. The oil fogs and titanium dioxide were found to deposit very quickly on the mock cylinder and obscure the motion of the particles. Based on initial calculations and flow measurements, the flow direction should have a negligible impact on PIV and swirl-meter results. The characterizations found in this project will be used in future engine research examining the effects of intake port geometry on in-cylinder fluid motion and exhaust gas recirculation tolerances. Thanks to NSF site grant #1358991.

Mode selection in swirling jet experiments: a linear stability analysis

NASA Astrophysics Data System (ADS)

Gallaire, François; Chomaz, Jean-Marc

2003-11-01

The primary goal of the study is to identify the selection mechanism responsible for the appearance of a double-helix structure in the pre-breakdown stage of so-called screened swirling jets for which the circulation vanishes away from the jet. The family of basic flows under consideration combines the azimuthal velocity profiles of Carton & McWilliams (1989) and the axial velocity profiles of Monkewitz (1988). This model satisfactorily represents the nozzle exit velocity distributions measured in the swirling jet experiment of Billant et al. (1998). Temporal and absolute/convective instability properties are directly retrieved from numerical simulations of the linear impulse response for different swirl parameter settings. A large range of negative helical modes, winding with the basic flow, are destabilized as swirl is increased, and their characteristics for large azimuthal wavenumbers are shown to agree with the asymptotic analysis of Leibovich & Stewartson (1983). However, the temporal study fails to yield a clear selection principle. The absolute/convective instability regions are mapped out in the plane of the external axial flow and swirl parameters. The absolutely unstable domain is enhanced by rotation and it remains open for arbitrarily large swirl. The swirling jet with zero external axial flow is found to first become absolutely unstable to a mode of azimuthal wavenumber m {=} {-}2, winding with the jet. It is suggested that this selection mechanism accounts for the experimental observation of a double-helix structure.

Injection Characteristics of Non-Swirling and Swirling Annular Liquid Sheets

NASA Technical Reports Server (NTRS)

Harper, Brent (Technical Monitor); Ibrahim, E. A.; McKinney, T. R.

2004-01-01

A simplified mathematical model, based on body-fitted coordinates, is formulated to study the evolution of non-swirling and swirling liquid sheet emanated from an annular nozzle in a quiescent surrounding medium. The model provides predictions of sheet trajectory, thickness and velocity at various liquid mass flow rates and liquid-swirler angles. It is found that a non-swirling annular sheet converges toward its centerline and assumes a bell shape as it moves downstream from the nozzle. The bell radius, and length are more pronounced at higher liquid mass flow rates. The thickness of the non-swirling annular sheet increases while its stream-wise velocity decreases with an increase in mass flow rate. The introduction of swirl results in the formation of a diverging hollow-cone sheet. The hollow-cone divergence from its centerline is enhanced by an increase in liquid mass flow rate or liquid-swirler angle. The hollow- cone sheet its radius, curvature and stream-wise velocity increase while its thickness and tangential velocity decrease as a result of increasing the mass flow rate or liquid-swirler angle. The present results are compared with previous studies and conclusions are drawn.

Swirl, Expansion Ratio and Blockage Effects on Confined Turbulent Flow. M.S. Thesis

NASA Technical Reports Server (NTRS)

Scharrer, G. L.

1982-01-01

A confined jet test facility, a swirles, flow visualization equipment, five-hole pitot probe instrumentation; flow visualization; and effects of swirl on open-ended flows, of gradual expansion on open-ended flows, and blockages of flows are addressed.

Mathematical modeling of swirled flows in industrial applications

NASA Astrophysics Data System (ADS)

Dekterev, A. A.; Gavrilov, A. A.; Sentyabov, A. V.

2018-03-01

Swirled flows are widely used in technological devices. Swirling flows are characterized by a wide range of flow regimes. 3D mathematical modeling of flows is widely used in research and design. For correct mathematical modeling of such a flow, it is necessary to use turbulence models, which take into account important features of the flow. Based on the experience of computational modeling of a wide class of problems with swirling flows, recommendations on the use of turbulence models for calculating the applied problems are proposed.

Gas turbine topping combustor

DOEpatents

Beer, Janos; Dowdy, Thomas E.; Bachovchin, Dennis M.

1997-01-01

A combustor for burning a mixture of fuel and air in a rich combustion zone, in which the fuel bound nitrogen in converted to molecular nitrogen. The fuel rich combustion is followed by lean combustion. The products of combustion from the lean combustion are rapidly quenched so as to convert the fuel bound nitrogen to molecular nitrogen without forming NOx. The combustor has an air radial swirler that directs the air radially inward while swirling it in the circumferential direction and a radial fuel swirler that directs the fuel radially outward while swirling it in the same circumferential direction, thereby promoting vigorous mixing of the fuel and air. The air inlet has a variable flow area that is responsive to variations in the heating value of the fuel, which may be a coal-derived fuel gas. A diverging passage in the combustor in front of a bluff body causes the fuel/air mixture to recirculate with the rich combustion zone.

Numerical simulation of a low-swirl impinging jet with a rotating convergent nozzle

NASA Astrophysics Data System (ADS)

Borynyak, K.; Hrebtov, M.; Bobrov, M.; Kozyulin, N.

2018-03-01

The paper presents the results of Large Eddy Simulation of a swirling impinging jet with moderate Reynolds number (104), where the swirl is organized via the rotation of a convergent nozzle. The results show that the effect of the swirl in this configuration leads to an increase of axial velocity, compared to the non-swirling case. It is shown that turbulent stress plays an important role in this effect. The vortex structure of the jet consists of multiple pairs of nearly parallel helical vortices with opposite signs of rotation. The interaction of vortices in the near region of the jet leads to radial contraction of the jet’s core which in turn, causes an the increase in the axial velocity.

Evolution of Rotor Wake in Swirling Flow

NASA Technical Reports Server (NTRS)

El-Haldidi, Basman; Atassi, Hafiz; Envia, Edmane; Podboy, Gary

2000-01-01

A theory is presented for modeling the evolution of rotor wakes as a function of axial distance in swirling mean flows. The theory, which extends an earlier work to include arbitrary radial distributions of mean swirl, indicates that swirl can significantly alter the wake structure of the rotor especially at large downstream distances (i.e., for moderate to large rotor-stator spacings). Using measured wakes of a representative scale model fan stage to define the mean swirl and initial wake perturbations, the theory is used to predict the subsequent evolution of the wakes. The results indicate the sensitivity of the wake evolution to the initial profile and the need to have complete and consistent initial definition of both velocity and pressure perturbations.

USSR Report, Engineering and Equipment

DTIC Science & Technology

1987-01-21

publications contain information primarily from foreign newspapers, periodicals and books, but also from news agency transmissions and broad- casts...NAUKA, No 2, Feb 86) 54 New Swirl-Type Ignition Systems for Gas Turbine Engines and Other Power Apparatus (K.A. Shchennikov, V.G. Tyryshkin, et...elements and differentiation with respect to the characteristic maneuver speed divided by the gravitation parameter as new variable, assuming that the

Influence of disk leakage path on labyrinth seal inlet swirl ratio

NASA Technical Reports Server (NTRS)

Kirk, R. Gordon

1987-01-01

The results of numerous investigators have shown the importance of labyrinth seal inlet swirl on the calculated dynamic stiffness of labyrinth seals. These results have not included any calculation of inlet leakage swirl as a function of geometry and sealing conditions of the given seal. This paper outlines a method of calculating the inlet swirl at a given seal by introducing a radial chamber to predict the gas swirl as it goes from the stage tip down to the seal location. For a centrifugal compressor, this amounts to including the flow path from the impeller discharge, down the back of the disk or front of the cover, then into the shaft seal or eye packing, respectively. The solution includes the friction factors of both the disk and stationary wall with account for mass flow rate and calculation of radial pressure gradients by a free vortex solution. The results of various configurations are discussed and comparisons made to other published results of disk swirl.

Does children's energy intake at one meal influence their intake at subsequent meals? Or do we just think it does?

PubMed

Hanley, James A; Hutcheon, Jennifer A

2010-05-01

It is widely believed that young children are able to adjust their energy intake across successive meals to compensate for higher or lower intakes at a given meal. This conclusion is based on past observations that although children's intake at individual meals is highly variable, total daily intakes are relatively constant. We investigated how much of this reduction in variability could be explained by the statistical phenomenon of the variability of individual components (each meal) always being relatively larger than the variability of their sum (total daily intake), independent of any physiological compensatory mechanism. We calculated, theoretically and by simulation, how variable a child's daily intake would be if there was no correlation between intakes at individual meals. We simulated groups of children with meal/snack intakes and variability in meal/snack intakes based on previously published values. Most importantly, we assumed that there was no correlation between intakes on successive meals. In both approaches, the coefficient of variation of the daily intakes was roughly 15%, considerably less than the 34% for individual meals. Thus, most of the reduction in variability found in past studies was explained without positing strong 'compensation'. Although children's daily energy intakes are indeed considerably less variable than their individual components, this phenomenon was observed even when intakes at each meal were simulated to be totally independent. We conclude that the commonly held belief that young children have a strong physiological compensatory mechanism to adjust intake at one meal based on intake at prior meals is likely to be based on flawed statistical reasoning.

LES of Swirling Reacting Flows via the Unstructured scalar-FDF Solver

NASA Astrophysics Data System (ADS)

Ansari, Naseem; Pisciuneri, Patrick; Strakey, Peter; Givi, Peyman

2011-11-01

Swirling flames pose a significant challenge for computational modeling due to the presence of recirculation regions and vortex shedding. In this work, results are presented of LES of two swirl stabilized non-premixed flames (SM1 and SM2) via the FDF methodology. These flames are part of the database for validation of turbulent-combustion models. The scalar-FDF is simulated on a domain discretized by unstructured meshes, and is coupled with a finite volume flow solver. In the SM1 flame (with a low swirl number) chemistry is described by the flamelet model based on the full GRI 2.11 mechanism. The SM2 flame (with a high swirl number) is simulated via a 46-step 17-species mechanism. The simulated results are assessed via comparison with experimental data.

Control of Vortex Breakdown in Critical Swirl Regime Using Azimuthal Forcing

NASA Technical Reports Server (NTRS)

Oberleithner, Kilian; Lueck, Martin; Paschereit, Christian Oliver; Wygnanski, Israel

2010-01-01

We finally go back to the four swirl cases and see how the flow responds to either forcing m = -1 or m = -2. On the left we see the flow forced at m = -1 We see that the PVC locks onto the applied forcing also for lower swirl number causing this high TKE at the jet center. The amplification of this instability causes VB to occur at a lower swirl number. The opposite can be seen when forcing the flow at m=-2 which is basically growing in the outer shear layer causing VB to move downstream . There is no energy at the center of the vortex showing that the precessing has been damped. The mean flow is most altered at the swirl numbers were VB is unstable.

The Widespread Distribution of Swirls in Lunar Reconnaissance Orbiter Camera Images

NASA Astrophysics Data System (ADS)

Denevi, B. W.; Robinson, M. S.; Boyd, A. K.; Blewett, D. T.

2015-10-01

Lunar swirls, the sinuous high-and low-reflectance features that cannot be mentioned without the associated adjective "enigmatic,"are of interest because of their link to crustal magnetic anomalies [1,2]. These localized magnetic anomalies create mini-magnetospheres [3,4] and may alter the typical surface modification processes or result in altogether distinct processes that form the swirls. One hypothesis is that magnetic anomalies may provide some degree of shielding from the solar wind [1,2], which could impede space weathering due to solar wind sputtering. In this case, swirls would serve as a way to compare areas affected by typical lunar space weathering (solar wind plus micrometeoroid bombardment) to those where space weathering is dominated by micrometeoroid bombardment alone, providing a natural means to assess the relative contributions of these two processes to the alteration of fresh regolith. Alternately,magnetic anomalies may play a role in the sorting of soil grains, such that the high-reflectance portion of swirls may preferentially accumulate feldspar-rich dust [5]or soils with a lower component of nanophase iron [6].Each of these scenarios presumes a pre-existing magnetic anomaly; swirlshave also been suggested to be the result of recent cometary impacts in which the remanent magnetic field is generated by the impact event[7].Here we map the distribution of swirls using ultraviolet and visible images from the Lunar Reconnaissance Orbiter Camera(LROC) Wide Angle Camera (WAC) [8,9]. We explore the relationship of the swirls to crustal magnetic anomalies[10], and examine regions with magnetic anomalies and no swirls.

Combustion characteristics and turbulence modeling of swirling reacting flow in solid fuel ramjet

NASA Astrophysics Data System (ADS)

Musa, Omer; Xiong, Chen; Changsheng, Zhou

2017-10-01

This paper reviews the historical studies have been done on the solid-fuel ramjet engine and difficulties associated with numerical modeling of swirling flow with combustible gases. A literature survey about works related to numerical and experimental investigations on solid-fuel ramjet as well as using swirling flow and different numerical approaches has been provided. An overview of turbulence modeling of swirling flow and the behavior of turbulence at streamline curvature and system rotation are presented. A new and simple curvature/correction factor is proposed in order to reduce the programming complexity of SST-CC turbulence model. Finally, numerical and experimental investigations on the impact of swirling flow on SFRJ have been carried out. For that regard, a multi-physics coupling code is developed to solve the problems of multi-physics coupling of fluid mechanics, solid pyrolysis, heat transfer, thermodynamics, and chemical kinetics. The connected-pipe test facility is used to carry out the experiments. The results showed a positive impact of swirling flow on SFRJ along with, three correlations are proposed.

Swirling flow in bileaflet mechanical heart valve

NASA Astrophysics Data System (ADS)

Gataulin, Yakov A.; Khorobrov, Svyatoslav V.; Yukhnev, Andrey D.

2018-05-01

Bileaflet mechanical valves are most commonly used for heart valve replacement. Nowadays swirling blood flow is registered in different parts of the cardiovascular system: left ventricle, aorta, arteries and veins. In present contribution for the first time the physiological swirling flow inlet conditions are used for numerical simulation of aortic bileaflet mechanical heart valve hemodynamics. Steady 3-dimensional continuity and RANS equations are employed to describe blood motion. The Menter SST model is used to simulate turbulence effects. Boundary conditions are corresponded to systolic peak flow. The domain was discretized into hybrid tetrahedral and hexahedral mesh with an emphasis on wall boundary layer. A system of equations was solved in Ansys Fluent finite-volume package. Noticeable changes in the flow structure caused by inlet swirl are shown. The swirling flow interaction with the valve leaflets is analyzed. A central orifice jet changes its cross-section shape, which leads to redistribution of wall shear stress on the leaflets. Transvalvular pressure gradient and area-averaged leaflet wall shear stress increase. Physiological swirl intensity noticeably reduces downstream of the valve.

Turbulence characteristics of swirling flowfields. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Jackson, T. W.; Lilley, D. G.

1985-01-01

The time mean and turbulence properties of a confined swirling jet using the six orientation, single hot wire technique were obtained. The effect of swirl on a confined, expanding jet is to reduce the size of the corner recirculation zone and generate a central recirculation zone followed by a precessing vortex core. The effect of introducing a contraction nozzle of area ratio four, located two test section diameters downstream of the inlet, is to dramatically reduce the size and shape of the central recirculation zone for the swirling flows considered. The shear stresses are found to increase by an order of magnitude in the region of the contraction nozzle because of large radial gradients of axial velocity. Reduction of the expansion ratio to D/o = 1 causes the time mean flow field to be homogeneous throughout the entire test section with the tangential velocity dominating in the swirling cases. No recirculation zones were observed for these particular flows. Turbulence levels and dissipation rates were found to be low except in the entrance regions and in areas of acceleration in the swirling flow cases.

The generation of sound by vorticity waves in swirling duct flows

NASA Technical Reports Server (NTRS)

Howe, M. S.; Liu, J. T. C.

1977-01-01

Swirling flow in an axisymmetric duct can support vorticity waves propagating parallel to the axis of the duct. When the cross-sectional area of the duct changes a portion of the wave energy is scattered into secondary vorticity and sound waves. Thus the swirling flow in the jet pipe of an aeroengine provides a mechanism whereby disturbances produced by unsteady combustion or turbine blading can be propagated along the pipe and subsequently scattered into aerodynamic sound. In this paper a linearized model of this process is examined for low Mach number swirling flow in a duct of infinite extent. It is shown that the amplitude of the scattered acoustic pressure waves is proportional to the product of the characteristic swirl velocity and the perturbation velocity of the vorticity wave. The sound produced in this way may therefore be of more significance than that generated by vorticity fluctuations in the absence of swirl, for which the acoustic pressure is proportional to the square of the perturbation velocity. The results of the analysis are discussed in relation to the problem of excess jet noise.

Assessment of swirl spray interaction in lab scale combustor using time-resolved measurements

NASA Astrophysics Data System (ADS)

Rajamanickam, Kuppuraj; Jain, Manish; Basu, Saptarshi

2017-11-01

Liquid fuel injection in highly turbulent swirling flows becomes common practice in gas turbine combustors to improve the flame stabilization. It is well known that the vortex bubble breakdown (VBB) phenomenon in strong swirling jets exhibits complicated flow structures in the spatial domain. In this study, the interaction of hollow cone liquid sheet with such coaxial swirling flow field has been studied experimentally using time-resolved measurements. In particular, much attention is focused towards the near field breakup mechanism (i.e. primary atomization) of liquid sheet. The detailed swirling gas flow field characterization is carried out using time-resolved PIV ( 3.5 kHz). Furthermore, the complicated breakup mechanisms and interaction of the liquid sheet are imaged with the help of high-speed shadow imaging system. Subsequently, proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) is implemented over the instantaneous data sets to retrieve the modal information associated with the interaction dynamics. This helps to delineate more quantitative nature of interaction process between the liquid sheet and swirling gas phase flow field.

Characteristics of the Swirling Flow Generated by an Axial Swirler

NASA Technical Reports Server (NTRS)

Fu, Yongqiang; Jeng, San-Mou; Tacina, Robert

2005-01-01

An experimental investigation was conducted to study the aerodynamic characteristics of the confined, non-reacting, swirling flow field. The flow was generated by a helicoidal axial-vaned swirler with a short internal convergent-divergent venturi, which was confined within 2-inch square test section. A series of helicoidal axial-vaned swirlers have been designed with tip vane angles of 40 deg., 45 deg., 50 deg., 55 deg., 60 deg. and 65 deg.. The swirler with the tip vane angle of 60 deg. was combined with several simulated fuel nozzle insertions of varying lengths. A two-component Laser Doppler Velocimetry (LDV) system was employed to measure the three-component mean velocities and Reynolds stresses. Detailed data are provided to enhance understanding swirling flow with different swirl degrees and geometries and to support the development of more accurate physicaVnumerica1 models. The data indicated that the degree of swirl had a clear impact on the mean and turbulent flow fields. The swirling flow fields changed significantly with the addition of a variety of simulated fuel nozzle insertion lengths

Characterization of Lunar Swirls at Mare Ingenii: A Model for Space Weathering at Magnetic Anomalies

NASA Technical Reports Server (NTRS)

Kramer, Georgianna Y.; Combe, Jean-Philippe; Harnett, Erika M.; Hawke, Bernard Ray; Noble, Sarah K.; Blewett, David T.; McCord, Thomas B.; Giguere, Thomas A.

2011-01-01

Analysis of spectra from the Clementine ultraviolet-visible and near-infrared cameras of small, immature craters and surface soils both on and adjacent to the lunar swirls at Marc Ingenii has yielded the following conclusions about space weathering at a magnetic anomaly. (l) Despite having spectral characteristics of immaturity, the lunar swirls arc not freshly exposed surfaces. (2) The swirl surfaces arc regions of retarded weathering, while immediately adjacent regions experience accelerated weathering, (3) Weathering in the off-swirl regions darkens and flattens the spectrum with little to no reddening, which suggests that the production of larger (greater than 40 nm) nanophase iron dominates in these locations as a result of charged particle sorting by the magnetic field. Preliminaty analysis of two other lunar swirl regions, Reiner Gamma and Mare Marginis, is consistent with our observations at Mare Ingenii. Our results indicate that sputtering/vapor deposition, implanted solar wind hydrogen, and agglutination share responsibility for creating the range in npFe(sup 0) particle sizes responsible for the spectral effects of space weathering.

Swirl ratio effects on tornado-like vortices

NASA Astrophysics Data System (ADS)

Hashemi-Tari, Pooyan; Gurka, Roi; Hangen, Horia

2007-11-01

The effect of swirl ratio on the flow field for a tornado-like vortex simulator (TVS) is investigated. Different swirl ratios are obtained by changing the geometry and tangential velocity which determine the vortex evolution. Flow visualizations, surface pressure and Particle Image Velocimetry (PIV) measurements are performed in a small TVS for swirl ratios S between 0 and 1. The PIV data was acquired for two orthogonal planes: normal and parallel to the solid boundary at several height locations. The ratio between the angular momentum and the radial momentum which characterize the swirl ratio is investigated. Statistical analysis to the turbulent field is performed by mean and rms profiles of the velocity, stresses and vorticity are presented. A Proper Orthogonal Decomposition (POD) is performed on the vorticity field. The results are used to: (i) provide a relation between these 3 sets of qualitative and quantitative measurements and the swirl ratio in an attempt to relate the fluid dynamics parameters to the forensic, Fujita scale, and (ii) understand the spatio-temporal distribution of the most energetic POD modes in a tornado-like vortex.

Effect of Chamber Backpressure on Swirl Injector Fluid Mechanics

NASA Technical Reports Server (NTRS)

Kenny, R. Jeremy; Hulka, James R.; Moser, Marlow D.; Rhys, Noah O.

2008-01-01

A common propellant combination used for high thrust generation is GH2/LOX. Historical GH2/LOX injection elements have been of the shear-coaxial type. Element type has a large heritage of research work to aid in element design. The swirl-coaxial element, despite its many performance benefits, has a relatively small amount of historical, LRE-oriented work to draw from. Design features of interest are grounded in the fluid mechanics of the liquid swirl process itself, are based on data from low-pressure, low mass flow rate experiments. There is a need to investigate how high ambient pressures and mass flow rates influence internal and external swirl features. The objective of this research is to determine influence of varying liquid mass flow rate and ambient chamber pressure on the intact-length fluid mechanics of a liquid swirl element.

Prediction of soot and thermal radiation in a model gas turbine combustor burning kerosene fuel spray at different swirl levels

NASA Astrophysics Data System (ADS)

Ghose, Prakash; Patra, Jitendra; Datta, Amitava; Mukhopadhyay, Achintya

2016-05-01

Combustion of kerosene fuel spray has been numerically simulated in a laboratory scale combustor geometry to predict soot and the effects of thermal radiation at different swirl levels of primary air flow. The two-phase motion in the combustor is simulated using an Eulerian-Lagragian formulation considering the stochastic separated flow model. The Favre-averaged governing equations are solved for the gas phase with the turbulent quantities simulated by realisable k-ɛ model. The injection of the fuel is considered through a pressure swirl atomiser and the combustion is simulated by a laminar flamelet model with detailed kinetics of kerosene combustion. Soot formation in the flame is predicted using an empirical model with the model parameters adjusted for kerosene fuel. Contributions of gas phase and soot towards thermal radiation have been considered to predict the incident heat flux on the combustor wall and fuel injector. Swirl in the primary flow significantly influences the flow and flame structures in the combustor. The stronger recirculation at high swirl draws more air into the flame region, reduces the flame length and peak flame temperature and also brings the soot laden zone closer to the inlet plane. As a result, the radiative heat flux on the peripheral wall decreases at high swirl and also shifts closer to the inlet plane. However, increased swirl increases the combustor wall temperature due to radial spreading of the flame. The high incident radiative heat flux and the high surface temperature make the fuel injector a critical item in the combustor. The injector peak temperature increases with the increase in swirl flow mainly because the flame is located closer to the inlet plane. On the other hand, a more uniform temperature distribution in the exhaust gas can be attained at the combustor exit at high swirl condition.

Distance effect on the behavior of an impinging swirling jet by PIV and flow visualizations

NASA Astrophysics Data System (ADS)

Felli, Mario; Falchi, Massimo; Pereira, Francisco Josè Alves

2010-02-01

The present paper deals with the problem of an impinging swirling jet against a wall. The study concerned a detailed experimental investigation on the jet-wall interaction using PIV and flow visualizations over a range of operating conditions in which the distance of the ducted propeller from the wall was changed. The influence of the impingement distance and the swirl number (i.e., ratio between the axial fluxes of the swirl and the axial momentum) as well as the interaction between the jet deformation and the perturbation induced on the wall is discussed in this paper.

Incorporating swirl effects into the coefficient of momentum for separation control

NASA Astrophysics Data System (ADS)

Taira, Kunihiko; Munday, Phillip

2017-11-01

Addition of swirl in flow control has been known to enhance suppression of separation over airfoils at high angles of attack. Utilizing large eddy simulations, the present open-loop control study examines the influence of wall-normal and angular momentum injections in mitigating separation over a NACA0012 airfoil at α =9° and Re = 23 , 000 . We introduce these swirling jets near the separation point with wall-normal momentum and swirl independently prescribed through velocity boundary conditions. The changes to the flow from control are examined and the corresponding lift enhancement and drag reduction are assessed as a function of the two velocity components. Since the standard coefficient of momentum does not consider swirling effects, we extend its definition to incorporate both the wall-normal momentum and swirl to quantify the overall flow control effectiveness. We are able to observe a trend in lift force enhancement over this single modified coefficient of momentum (that is dependent on the non-dimensional jet velocity ratio and swirl number). Moreover, we are able to identify a critical value for the modified momentum coefficient and categorize controlled flows into separated, transitional, and attached flows. This work was supported by the Air Force Office of Scientific Research (Award Number FA9550-13-1-0183) and the Office of Naval Research (Award Number N00014-16-1-2443).

Turbulence Characteristics of Swirling Flowfields. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Jackson, T. W.

1983-01-01

Combustor design phenomena; recirculating flows research; single-wire, six-orientation, eddy dissipation rate, and turbulence modeling measurement; directional sensitivity (DS); calibration equipment, confined jet facility, and hot-wire instrumentation; effects of swirl, strong contraction nozzle, and expansion ratio; and turbulence parameters; uncertain; and DS in laminar jets; turbulent nonswirling jets, and turbulent swirling jets are discussed.

Heat and mass transfer and hydrodynamics in swirling flows (review)

NASA Astrophysics Data System (ADS)

Leont'ev, A. I.; Kuzma-Kichta, Yu. A.; Popov, I. A.

2017-02-01

Research results of Russian and foreign scientists of heat and mass transfer in whirling flows, swirling effect, superficial vortex generators, thermodynamics and hydrodynamics at micro- and nanoscales, burning at swirl of the flow, and technologies and apparatuses with the use of whirling currents for industry and power generation were presented and discussed at the "Heat and Mass Transfer in Whirling Currents" 5th International Conference. The choice of rational forms of the equipment flow parts when using whirling and swirling flows to increase efficiency of the heat-power equipment and of flow regimes and burning on the basis of deep study of the flow and heat transfer local parameters was set as the main research prospect. In this regard, there is noticeable progress in research methods of whirling and swirling flows. The number of computational treatments of swirling flows' local parameters has been increased. Development and advancement of the up to date computing models and national productivity software are very important for this process. All experimental works are carried out with up to date research methods of the local thermoshydraulic parameters, which enable one to reveal physical mechanisms of processes: PIV and LIV visualization techniques, high-speed and infrared photography, high speed registration of parameters of high-speed processes, etc. There is a problem of improvement of researchers' professional skills in the field of fluid mechanics to set adequately mathematics and physics problems of aerohydrodynamics for whirling and swirling flows and numerical and pilot investigations. It has been pointed out that issues of improvement of the cooling system and thermal protection effectiveness of heat-power and heat-transfer equipment units are still actual. It can be solved successfully using whirling and swirling flows as simple low power consumption exposing on the flow method and heat transfer augmentation.

Effects of Jet Swirl on Mixing of a Light Gas Jet in a Supersonic Airstream

NASA Technical Reports Server (NTRS)

Doerner, Steven E.; Cutler, Andrew D.

1999-01-01

A non reacting experiment was performed to investigate the effects of jet swirl on mixing of a light gas jet in a supersonic airstream. The experiment consisted of two parts. The first part was an investigation of the effects of jet swirl and skew on the mixing and penetration of a 25 deg. supersonic jet injected from a flat surface (flush wall injection) into a supersonic ducted airflow. Specifically, the objective was to determine whether the jet would mix more rapidly if the jet were swirling, and whether swirl, with and without skew, causes the injectant-air plume to have a net circulation (i.e., a single or dominant vortex). The second part was a preliminary study of the mixing of swirling jets injected from the base of a skewed ramp. The hypothesis was that favorable interactions between vorticity generated by the swirling jet and vortices generated by the ramp could produce mixing enhancements. Both parts of the experiment were conducted at equal injectant mass flow rate and total pressure. The results for the flush wall injection cases indicate that, except relatively close to the injection point, swirl, with or without skew, does not enhance the mixing of the jet, and can in fact reduce penetration. In addition, a plume with significant net circulation is not generated, as had previously been believed. The results for the ramp cases indicated no improvements in mixing in comparison with the baseline (swept ramp injector) case. However, it was not possible to determine the vorticity mechanisms underlying the poor performance, since no measurements of vorticity were made. Thus, since many geometric parameters were chosen arbitrarily, the results are inconclusive for this class of injector.

Axial vane-type swirler performance characteristics. M.S. Thesis

NASA Technical Reports Server (NTRS)

Sander, G. F.

1983-01-01

The performance of an axial vane-type swirler was investigated to aid in computer modeling of gas turbine combustor flowfields and in evaluation of turbulence models for swirling confined jet flow. The swirler studied is annular with a hub-to-swirler diameter ratio of 0.25 and ten adjustable vanes of pitch-to-chord ratio 0.68. Measurements of time-mean axial, radial, and tangential velocities were made at the swirler exit plane using a five-hole pitot probe technique with computer data reduction. Nondimensionalized velocities from both radial and azimuthal traverses are tabulated and plotted for a range of swirl vane angles phi from 0 to 70 degrees. A study was done of idealized exit-plane velocity profiles relating the swirl numbers S and S' to the ratio of maximum swirl and axial velocities for each idealized case, and comparing the idealized swirl numbers with ones calculated from measured profiles.

Vorticity Dynamics in Single and Multiple Swirling Reacting Jets

NASA Astrophysics Data System (ADS)

Smith, Travis; Aguilar, Michael; Emerson, Benjamin; Noble, David; Lieuwen, Tim

2015-11-01

This presentation describes an analysis of the unsteady flow structures in two multinozzle swirling jet configurations. This work is motivated by the problem of combustion instabilities in premixed flames, a major concern in the development of modern low NOx combustors. The objective is to compare the unsteady flow structures in these two configurations for two separate geometries and determine how certain parameters, primarily distance between jets, influence the flow dynamics. The analysis aims to differentiate between the flow dynamics of single nozzle and triple nozzle configurations. This study looks at how the vorticity in the shear layers of one reacting swirling jet can affect the dynamics of a nearby similar jet. The distance between the swirling jets is found to have an effect on the flow field in determining where swirling jets merge and on the dynamics upstream of the merging location. Graduate Student, School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA.

Analytic studies on satellite detection of severe, two-cell tornadoes

NASA Technical Reports Server (NTRS)

Carrier, G. F.; Dergarabedian, P.; Fendell, F. E.

1979-01-01

From funnel-cloud-length interpretation, the severe tornado is characterized by peak swirl speed relative to the axis of rotation of about 90 m/s. Thermohydrodynamic achievement of the pressure deficit from ambient necessary to sustain such swirls requires that a dry, compressionally heated, non-rotating downdraft of initially tropopause-level air lie within an annulus of rapidly swirling, originally low-level air ascending on a near-moist-adiabatic locus of thermodynamic states. The two-cell structure furnishes an observable parameter possibly accessible to a passively instrumented, geosynchronous meteorological satellite with mesoscale resolution, for early detection of a severe tornado. Accordingly, the low-level turnaround region, in which the surface inflow layer separates to become a free ascending layer and for which inviscid modeling suffices, is examined quantitatively. Preliminary results indicate that swirl overshoot, i.e., swirl speeds in the turnaround region in excess of the maximum achieved in the potential vortex, is modest.

Turbulence measurements in a swirling confined jet flowfield using a triple hot-wire probe

NASA Technical Reports Server (NTRS)

Janjua, S. I.; Mclaughlin, D. K.

1982-01-01

An axisymmetric swirling confined jet flowfield, similar to that encountered in gas turbine combustors was investigated using a triple hot-wire probe. The raw data from the three sensors were digitized using ADC's and stored on a Tektronix 4051 computer. The data were further reduced on the computer to obtain time-series for the three instantaneous velocity components in the flowfield. The time-mean velocities and the turbulence quantities were deduced. Qualification experiments were performed and where possible results compared with independent measurements. The major qualification experiments involved measurements performed in a non-swirling flow compared with conventional X-wire measurements. In the swirling flowfield, advantages of the triple wire technique over the previously used multi-position single hot-wire method are noted. The measurements obtained provide a data base with which the predictions of turbulence models in a recirculating swirling flowfield can be evaluated.

Emissions of Jatropha oil-derived biodiesel blend fuels during combustion in a swirl burner

NASA Astrophysics Data System (ADS)

Norwazan, A. R.; Mohd. Jaafar, M. N.; Sapee, S.; Farouk, Hazir

2018-03-01

Experimental works on combustion of jatropha oil biodiesel blends of fuel with high swirling flow in swirl burner have been studied in various blends percentage. Jatropha oil biodiesel was produced using a two-step of esterification-transesterification process. The paper focuses on the emissions of biodiesel blends fuel using jatropha oil in lean through to rich air/fuel mixture combustion in swirl burner. The emissions performances were evaluated by using axial swirler amongst jatropha oil blends fuel including diesel fuel as baseline. The results show that the B25 has good emissions even though it has a higher emission of NOx than diesel fuel, while it emits as low as 42% of CO, 33% of SO2 and 50% of UHC emissions with high swirl number. These are due to the higher oxygen content in jatropha oil biodiesel.

Observations of Lunar Swirls by the Diviner Lunar Radiometer Experiment

NASA Technical Reports Server (NTRS)

Glotch, T. D.; Greenhagen, B. T.; Lucey, P. G.; Bandfield, J. L.; Hayne, Paul O.; Allen, Carlton C.; Elphic, Richard C.; Paige, D. A.

2012-01-01

The presence of anomalous, high albedo markings on the lunar surface has been known since the Apollo era. These features, collectively known as lunar swirls, occur on both the mare and highlands. Some swirls are associated with the antipodes of major impact basins, while all are associated with magnetic field anomalies of varying strength. Three mechanisms have been proposed for the formation of the swirls: (1) solar wind standoff due to the presence of magnetic fields, (2) micrometeoroid or comet swarms impacting and disturbing the lunar surface, revealing unweathered regolith, and (3) transport and deposition of fine-grained feldspathic material. Diviner s unique capabilities to determine silicate composition and degree of space weathering of the lunar surface, in addition to its capabilities to determine thermophysical properties from night-time temperature measurements, make it an ideal instrument to examine the swirls and help differentiate among the three proposed formation mechanisms.

Review on pressure swirl injector in liquid rocket engine

NASA Astrophysics Data System (ADS)

Kang, Zhongtao; Wang, Zhen-guo; Li, Qinglian; Cheng, Peng

2018-04-01

The pressure swirl injector with tangential inlet ports is widely used in liquid rocket engine. Commonly, this type of pressure swirl injector consists of tangential inlet ports, a swirl chamber, a converging spin chamber, and a discharge orifice. The atomization of the liquid propellants includes the formation of liquid film, primary breakup and secondary atomization. And the back pressure and temperature in the combustion chamber could have great influence on the atomization of the injector. What's more, when the combustion instability occurs, the pressure oscillation could further affects the atomization process. This paper reviewed the primary atomization and the performance of the pressure swirl injector, which include the formation of the conical liquid film, the breakup and atomization characteristics of the conical liquid film, the effects of the rocket engine environment, and the response of the injector and atomization on the pressure oscillation.

Understanding Student Swirl: The Role of Environmental Factors and Retention Efforts in the Later Academic Success of Suspended Students

ERIC Educational Resources Information Center

Wang, Yan; Pilarzyk, Tom

2010-01-01

"Student swirl," or the inconsistent flow in and out of college coursework from term-to-term, institution-to-institution, reflects the non-traditional nature of many community college students. Swirl can be triggered by such stressors as: balancing work, school, and family obligations; financial challenges; and health problems. In turn,…

Swirling flow of a dissociated gas

NASA Technical Reports Server (NTRS)

Wolfram, W. R., Jr.; Walker, W. F.

1975-01-01

Most physical applications of the swirling flow, defined as a vortex superimposed on an axial flow in the nozzle, involve high temperatures and the possibility of real gas effects. The generalized one-dimensional swirling flow in a converging-diverging nozzle is analyzed for equilibrium and frozen dissociation using the ideal dissociating gas model. Numerical results are provided to illustrate the major effects and to compare with results obtained for a perfect gas with constant ratio of specific heats. It is found that, even in the case of real gases, perfect gas calculations can give a good estimate of the reduction in mass flow due to swirl.

Test results for rotordynamic coefficients of anti-swirl self-injection seals

NASA Technical Reports Server (NTRS)

Kim, C. H.; Lee, Y. B.

1994-01-01

Test results are presented for rotordynamic coefficients and leakage for three annular seals which use anti-swirl self-injection concept to yield significant improvement in whirl frequency ratios as compared to smooth and damper seals. A new anti-swirl self-inection mechanism is achieved by deliberately machining self-injection holes inside the seal stator mechanism which is used to achieve effective reduction of the tangential flow which is considered as a prime cause of rotor instability in high performance turbomachinery. Test results show that the self-injection mechanism significantly improves whirl frequency ratios; however, the leakage performance degrades due to the introduction of the self-injection mechanism. Through a series of the test program, an optimum anti-swirl self-injection seal which uses a labyrinth stator surface with anti-axial flow injections is selected to obtain a significant improvement in the whirl frequency ratio as compared to a damper seal, while showing moderate leakage performance. Best whirl frequency ratio is achieved by an anti-swirl self-injection seal of 12 holes anti-swirl and 6 degree anti-leakage injection with a labyrinth surface configuration. When compared to a damper seal, the optimum configuration outperforms the whirl frequency ratio by a factor of 2.

Modeling and Simulation of Swirl Stabilized Turbulent Non-Premixed Flames

NASA Astrophysics Data System (ADS)

Badillo-Rios, Salvador; Karagozian, Ann

2017-11-01

Flame stabilization is an important design criterion for many combustion chambers, especially at lean conditions and/or high power output, where insufficient stabilization can result in dangerous oscillations and noisy or damaged combustors. At high flow rates, swirling flow can offer a suitable stabilization mechanism, although understanding the dynamics of swirl-stabilized turbulent flames remains a significant challenge. Utilizing the General Equation and Mesh Solver (GEMS) code, which solves the Navier-Stokes equations along with the energy equation and five species equations, 2D axisymmetric and full 3D parametric studies and simulations are performed to guide the design and development of an experimental swirl combustor configuration and to study the effects of swirl on statistically stationary combustion. Results show that as the momentum of air is directed into the inner air inlet rather than the outer inlet of the swirl combustor, the central recirculating region becomes stronger and more unsteady, improving mixing and burning efficiency in that region. A high temperature region is found to occur as a result of burning of the trapped fuel from the central toroidal vortex. The effects of other parameters on flowfield and flame-stabilization dynamics are explored. Supported by ERC, Inc. (PS150006) and AFOSR (Dr. Chiping Li).

Getting drowned in a swirl: Deformable bead-spring model microswimmers in external flow fields

NASA Astrophysics Data System (ADS)

Küchler, Niklas; Löwen, Hartmut; Menzel, Andreas M.

2016-02-01

Deformability is a central feature of many types of microswimmers, e.g., for artificially generated self-propelled droplets. Here, we analyze deformable bead-spring microswimmers in an externally imposed solvent flow field as simple theoretical model systems. We focus on their behavior in a circular swirl flow in two spatial dimensions. Linear (straight) two-bead swimmers are found to circle around the swirl with a slight drift to the outside with increasing activity. In contrast to that, we observe for triangular three-bead or squarelike four-bead swimmers a tendency of being drawn into the swirl and finally getting drowned, although a radial inward component is absent in the flow field. During one cycle around the swirl, the self-propulsion direction of an active triangular or squarelike swimmer remains almost constant, while their orbits become deformed exhibiting an "egglike" shape. Over time, the swirl flow induces slight net rotations of these swimmer types, which leads to net rotations of the egg-shaped orbits. Interestingly, in certain cases, the orbital rotation changes sense when the swimmer approaches the flow singularity. Our predictions can be verified in real-space experiments on artificial microswimmers.

Integrated Fuel Injection and Mixing System with Impingement Cooling Face

NASA Technical Reports Server (NTRS)

Mansour, Adel B. (Inventor); Harvey, Rex J. (Inventor); Tacina, Robert R. (Inventor); Laing, Peter (Inventor)

2003-01-01

An atomizing injector includes a metering set having a swirl chamber, a spray orifice and one or more feed slots etched in a thin plate. The swirl chamber is etched in a first side of the plate and the spray orifice is etched through a second side to the center of the swirl chamber. Fuel feed slots extend non-radially to the swirl chamber. The injector also includes integral swirler structure. The swirler structure includes a cylindrical air swirler passage, also shaped by etching, through at least one other thin plate. The cylindrical air swirler passage is located in co-axial relation to the spray orifice of the plate of the fuel metering set such that fuel directed through the spray orifice passes through the air swirler passage and swirling air is imparted to the fuel such that the fuel has a swirling component of motion. At least one air feed slot is provided in fluid communication with the air swirler passage and extends in non-radial relation thereto. Air supply passages extend through the plates of the metering set and the swirler structure to feed the air feed slot in each plate of the swirler structure.

Swirling cavitation improves the emulsifying properties of commercial soy protein isolate.

PubMed

Yang, Feng; Liu, Xue; Ren, Xian'e; Huang, Yongchun; Huang, Chengdu; Zhang, Kunming

2018-04-01

Since emulsifying properties are important functional properties of soy protein, many physical, chemical, and enzymatic methods have been applied to treat soy protein to improve emulsifying properties. In this study, we investigated the effects of swirling cavitation at different pressures and for different times on emulsifying and physicochemical properties of soy protein isolate (SPI). The SPI treated with swirling cavitation showed a significant decrease in particle size and increase in solubility. Emulsions formed from treated SPI had higher emulsifying activity and emulsifying stability indexes, smaller oil droplet sizes, lower flocculation indexes, higher adsorbed proteins, lower interfacial protein concentrations, and lower creaming indexes than those formed from untreated SPI, indicating that swirling cavitation improved the emulsifying properties of the SPI. Furthermore, swirling cavitation treatment significantly enhanced the surface hydrophobicity, altered the disulfide bond and exposed sulfhydryl group contents of the SPI. The secondary structure of the SPI was also influenced by swirling cavitation, with an increase in β-sheet content and a decrease in α-helix, β-turn, and random coil contents. In addition, several significant correlations between physicochemical and emulsifying properties were revealed by Pearson correlation analysis, suggesting that the physicochemical changes observed in treated SPI, including the decreased particle size, increased solubility and surface hydrophobicity, and enhanced β-sheet formation, may explain the improved emulsifying properties of the isolate. Thus, our findings implied that swirling cavitation treatment may be an effective technique to improve the emulsifying properties of SPI. Copyright © 2017 Elsevier B.V. All rights reserved.

Gas turbine topping combustor

DOEpatents

Beer, J.; Dowdy, T.E.; Bachovchin, D.M.

1997-06-10

A combustor is described for burning a mixture of fuel and air in a rich combustion zone, in which the fuel bound nitrogen in converted to molecular nitrogen. The fuel rich combustion is followed by lean combustion. The products of combustion from the lean combustion are rapidly quenched so as to convert the fuel bound nitrogen to molecular nitrogen without forming NOx. The combustor has an air radial swirler that directs the air radially inward while swirling it in the circumferential direction and a radial fuel swirler that directs the fuel radially outward while swirling it in the same circumferential direction, thereby promoting vigorous mixing of the fuel and air. The air inlet has a variable flow area that is responsive to variations in the heating value of the fuel, which may be a coal-derived fuel gas. A diverging passage in the combustor in front of a bluff body causes the fuel/air mixture to recirculate with the rich combustion zone. 14 figs.

Aperiodic pressure pulsation under non optimal hydraulic turbine regimes at low swirl number

NASA Astrophysics Data System (ADS)

Skripkin, S. G.; Tsoy, M. A.; Kuibin, P. A.; Shtork, S. I.

2017-09-01

Off-design operating conditions of hydraulic turbines is hindered by pressure fluctuations in the draft tube of the turbine. A precessing helical vortex rope develops, which imperils the mechanical structure and limits the operation flexibility of hydropower station. Understanding of the underlying instabilities of precessing vortex rope at low swirl number is incomplete. In this paper flow regimes with different residual swirl is analysed, particular attention is paid to the regime with a small swirl parameter. Study defines upper and low boundaries of regime where aperiodic pressure surge is observed. Flow field at the runner exit is investigated by Laser Doppler Velocimetry and high-speed visualizations, which are complemented draft tube wall pressure measurements.

Atomization characteristics of swirl injector sprays

NASA Technical Reports Server (NTRS)

Feikema, Douglas A.

1996-01-01

Stable combustion within rocket engines is a continuing concern for designers of rocket engine systems. The swirl-coaxial injector has demonstrated effectiveness in achieving atomization and mixing, and therefore stable combustion. Swirl-coaxial injector technology is being deployed in the American RL1OA rocket design and Russian engine systems already make wide spread use of this technology. The present requirement for swirl injector research is derived from NASA's current Reusable Launch Vehicle (RLV) technology program. This report describes some of the background and literature on this topic including drop size measurements, comparison with theoretical predictions, the effect of surface tension on the atomization process, and surface wave characteristics of liquid film at the exit of the injector.

Steady axisymmetric vortex flows with swirl and shear

NASA Astrophysics Data System (ADS)

Elcrat, Alan R.; Fornberg, Bengt; Miller, Kenneth G.

A general procedure is presented for computing axisymmetric swirling vortices which are steady with respect to an inviscid flow that is either uniform at infinity or includes shear. We consider cases both with and without a spherical obstacle. Choices of numerical parameters are given which yield vortex rings with swirl, attached vortices with swirl analogous to spherical vortices found by Moffatt, tubes of vorticity extending to infinity and Beltrami flows. When there is a spherical obstacle we have found multiple solutions for each set of parameters. Flows are found by numerically solving the Bragg-Hawthorne equation using a non-Newton-based iterative procedure which is robust in its dependence on an initial guess.

Helicity of a toroidal vortex with swirl

NASA Astrophysics Data System (ADS)

Bannikova, E. Yu.; Kontorovich, V. M.; Poslavsky, S. A.

2016-04-01

Based on the solutions of the Bragg-Hawthorne equation, we discuss the helicity of a thin toroidal vortex in the presence of swirl, orbital motion along the torus directrix. The relation between the helicity and circulations along the small and large linked circumferences (the torus directrix and generatrix) is shown to depend on the azimuthal velocity distribution in the core of the swirling ring vortex. In the case of nonuniform swirl, this relation differs from the well-known Moffat relation, viz., twice the product of such circulations multiplied by the number of linkages. The results can find applications in investigating the vortices in planetary atmospheres and the motions in the vicinity of active galactic nuclei.

Simulation of blood flow in a small-diameter vascular graft model with a swirl (spiral) flow guider.

PubMed

Zhang, ZhiGuo; Fan, YuBo; Deng, XiaoYan; Wang, GuiXue; Zhang, He; Guidoin, Robert

2008-10-01

Small-diameter vascular grafts are in large demand for coronary and peripheral bypass procedures, but present products still fail in long-term clinical application. In the present communication, a new type of small-diameter graft with a swirl flow guider was proposed to improve graft patency rate. Flow pattern in the graft was simulated numerically and compared with that in a conventional graft. The numerical results revealed that the swirl flow guider could indeed make the blood flow rotate in the new graft. The swirling flow distal to the flow guider significantly altered the flow pattern in the new graft and the velocity profiles were re-distributed. Due to the swirling flow, the blood velocity near the vessel wall and wall shear rate were greatly enhanced. We believe that the increased blood velocity near the wall and the wall shear rate can impede the occurrence of acute thrombus formation and intimal hyperplasia, hence can improve the graft patency rate for long-term clinical use.

Fuel flexible fuel injector

DOEpatents

Tuthill, Richard S; Davis, Dustin W; Dai, Zhongtao

2015-02-03

A disclosed fuel injector provides mixing of fuel with airflow by surrounding a swirled fuel flow with first and second swirled airflows that ensures mixing prior to or upon entering the combustion chamber. Fuel tubes produce a central fuel flow along with a central airflow through a plurality of openings to generate the high velocity fuel/air mixture along the axis of the fuel injector in addition to the swirled fuel/air mixture.

Insights into flame-flow interaction during boundary layer flashback of swirl flames

NASA Astrophysics Data System (ADS)

Ranjan, Rakesh; Ebi, Dominik; Clemens, Noel

2017-11-01

Boundary layer flashback in swirl flames is a frequent problem in industrial gas turbine combustors. During this event, an erstwhile stable swirl flame propagates into the upstream region of the combustor, through the low momentum region in the boundary layer. Owing to the involvement of various physical factors such as turbulence, flame-wall interactions and flame-flow interactions, the current scientific understanding of this phenomenon is limited. The transient and three-dimensional nature of the swirl flow, makes it even more challenging to comprehend the underlying physics of the swirl flame flashback. In this work, a model swirl combustor with an axial swirler and a centerbody was used to carry out the flashback experiments. We employed high-speed chemiluminescence imaging and simultaneous stereoscopic PIV to understand the flow-flame interactions during flashback. A novel approach to reconstruct the three-dimensional flame surface using time-resolved slice information is utilized to gain insight into the flame-flow interaction. It is realized that the blockage effect imposed by the flame deflects the approaching streamlines in axial as well as azimuthal directions. A detailed interpretation of streamline deflection during boundary layer flashback shall be presented. This work was sponsored by the DOE NETL under Grant DEFC2611-FE0007107.

Axisymmetric Vortices with Swirl

NASA Astrophysics Data System (ADS)

Elcrat, A.

2007-11-01

This talk is concerned with finding solutions of the Euler equations by solving elliptic boundary value problems for the Bragg-Hawthorne equation L u= -urr -(1/r)ur - = r^2f (u) + h(u). Theoretical results have been given for previously (Elcrat and Miller, Differential and Integral Equations 16(4) 2003, 949-968) for problems with swirl and general classes of profile functions f, h by iterating Lu(n+1)= rf(u)n)) + h(u(n)), and showing u(n) converges montonically to a solution. The solutions obtained depend on the initial guess, which can be thought of as prescribing level sets of the vortex. When a computational program was attempted these monotone iterations turned out to be numerically unstable, and a stable computation was acheived by fixing the moment of the cross section of a vortex in the merideanal plane. (This generalizes previous computational results in Elcrat, Fornberg and Miller, JFM 433 2001, (315-328) We obtain famillies of vortices related to vortex rings with swirl, Moffatt's generalization of Hill's vortex and tubes of vorticity with swirl wrapped around the symmetry axis. The vortices are embedded in either an irrotational flow or a flow with shear, and we deal with the transition form no swirl in the vortex to flow with only swirl, a Beltrami flow.

Modeling of Turbulent Swirling Flows

NASA Technical Reports Server (NTRS)

Shih, Tsan-Hsing; Zhu, Jiang; Liou, William; Chen, Kuo-Huey; Liu, Nan-Suey; Lumley, John L.

1997-01-01

Aircraft engine combustors generally involve turbulent swirling flows in order to enhance fuel-air mixing and flame stabilization. It has long been recognized that eddy viscosity turbulence models are unable to appropriately model swirling flows. Therefore, it has been suggested that, for the modeling of these flows, a second order closure scheme should be considered because of its ability in the modeling of rotational and curvature effects. However, this scheme will require solution of many complicated second moment transport equations (six Reynolds stresses plus other scalar fluxes and variances), which is a difficult task for any CFD implementations. Also, this scheme will require a large amount of computer resources for a general combustor swirling flow. This report is devoted to the development of a cubic Reynolds stress-strain model for turbulent swirling flows, and was inspired by the work of Launder's group at UMIST. Using this type of model, one only needs to solve two turbulence equations, one for the turbulent kinetic energy k and the other for the dissipation rate epsilon. The cubic model developed in this report is based on a general Reynolds stress-strain relationship. Two flows have been chosen for model evaluation. One is a fully developed rotating pipe flow, and the other is a more complex flow with swirl and recirculation.

Modeling and simulation of combustion dynamics in lean-premixed swirl-stabilized gas-turbine engines

NASA Astrophysics Data System (ADS)

Huang, Ying

This research focuses on the modeling and simulation of combustion dynamics in lean-premixed gas-turbines engines. The primary objectives are: (1) to establish an efficient and accurate numerical framework for the treatment of unsteady flame dynamics; and (2) to investigate the parameters and mechanisms responsible for driving flow oscillations in a lean-premixed gas-turbine combustor. The energy transfer mechanisms among mean flow motions, periodic motions and background turbulent motions in turbulent reacting flow are first explored using a triple decomposition technique. Then a comprehensive numerical study of the combustion dynamics in a lean-premixed swirl-stabilized combustor is performed. The analysis treats the conservation equations in three dimensions and takes into account finite-rate chemical reactions and variable thermophysical properties. Turbulence closure is achieved using a large-eddy-simulation (LES) technique. The compressible-flow version of the Smagorinsky model is employed to describe subgrid-scale turbulent motions and their effect on large-scale structures. A level-set flamelet library approach is used to simulate premixed turbulent combustion. In this approach, the mean flame location is modeled using a level-set G-equation, where G is defined as a distance function. Thermophysical properties are obtained using a presumed probability density function (PDF) along with a laminar flamelet library. The governing equations and the associated boundary conditions are solved by means of a four-step Runge-Kutta scheme along with the implementation of the message passing interface (MPI) parallel computing architecture. The analysis allows for a detailed investigation into the interaction between turbulent flow motions and oscillatory combustion of a swirl-stabilized injector. Results show good agreement with an analytical solution and experimental data in terms of acoustic properties and flame evolution. A study of flame bifurcation from a stable state to an unstable state indicates that the inlet flow temperature and equivalence ratio are the two most important variables determining the stability characteristics of the combustor. Under unstable operating conditions, several physical processes responsible for driving combustion instabilities in the chamber have been identified and quantified. These processes include vortex shedding and acoustic interaction, coupling between the flame evolution and local flow oscillations, vortex and flame interaction and coupling between heat release and acoustic motions. The effects of inlet swirl number on the flow development and flame dynamics in the chamber are also carefully studied. In the last part of this thesis, an analytical model is developed using triple decomposition techniques to model the combustion response of turbulent premixed flames to acoustic oscillations.

Swirl Ring Improves Performance Of Welding Torch

NASA Technical Reports Server (NTRS)

Mcgee, William F.; Rybicki, Daniel J.

1995-01-01

Plasma-arc welding torch modified to create vortex in plasma gas to focus arc into narrower and denser column. Swirl ring contains four channels with angled exit holes to force gas to swirl as it flows out of torch past tip of electrode. Degradation of electrode and orifice more uniform and need to rotate torch during operation to compensate for asymmetry in arc reduced or eliminated. Used in both keyhole and nonkeyhole welding modes.

A study of high speed flows in an aircraft transition duct. Ph.D. Thesis - Iowa State Univ.

NASA Technical Reports Server (NTRS)

Reichert, Bruce A.

1991-01-01

The study of circular-to-rectangular transition duct flows with and without inlet swirl is presented. A method was devised to create a swirling, solid body rotational flow with minimal associated disturbances. Details of the swirl generator design and construction are discussed. Coefficients based on velocities and total and static pressures measured in cross stream planes at four axial locations within the transition duct along with surface static pressures and surface oil film visualization are presented for both nonswirling and swirling incoming flows. A method was developed to acquire trace gas measurements within the transition duct at high flow velocities. Statistical methods are used to help interpret the trace gas results.

Lean Premixed Combustion Stabilized by Low Swirl a Promising Concept for Practical Applications

NASA Technical Reports Server (NTRS)

Cheng, R. K.

1999-01-01

Since its inception, the low-swirl burner (LSB) has shown to be a useful laboratory apparatus for fundamental studies of premixed turbulent flames. The LSB operates under wide ranges of equivalence ratios, flow rates, and turbulence intensities. Its flame is lifted and detached from the burner and allows easy access for laser diagnostics. The flame brush is axisymmetric and propagates normal to the incident reactants. Therefore, the LSB is well suited for investigating detailed flame structures and empirical coefficients such as flame speed, turbulence transport, and flame generated turbulence. Due to its capability to stabilize ultra-lean premixed turbulent flames (phi approx. = 0.55), the LSB has generated interest from the gas appliance industry for use as an economical low-NO(x) burner. Lean premixed combustion emits low levels of NO(x), due primarily to the low flame temperature. Therefore, it is a very effective NO(x) prevention method without involving selective catalytic reduction (SCR), fuel-air staging, or flue gas recirculation (FGR). En the gas turbine industry, substantial research efforts have already been undertaken and engines with lean premixed combustors are already in use. For commercial and residential applications, premixed pulsed combustors and premixed ceramic matrix burners are commercially available. These lean premixed combustion technologies, however, tend to be elaborate but have relatively limited operational flexibility, and higher capital, operating and maintenance costs. Consequently, these industries are continuing the development of lean premixed combustion technologies as well as exploring new concepts. This paper summarizes the research effects we have undertaken in the past few years to demonstrate the feasibility of applying the low-swirl flame stabilization method for a wide range of heating and power generation systems. The principle of flame stabilization by low-swirl is counter to the conventional high-swirl methods that rely on a recirculation zone to anchor the flame. In LSBS, flow recirculation is not promoted to allow the premixed turbulent flames to propagate freely. A LSB with an air-jet swirler is essentially an open tube with the swirler at its mid section. The small air-jets generate swirling motion only in the annular region and leaving the central core of the flow undisturbed, When this flow exits the burner tube, the angular momentum generates radial mean pressure gradient to diverge the non-swirling reactants stream. Consequently, the mean flow velocity decreases linearly. Propagating against this decelerating flow, the flame self-sustains at the position where the local flow velocity equals the flame speed, S(sub f). The LSB operates with a swirl number, S, between 0.02 to 0.1. This is much lower than the minimum S of 0.6 required for the high-swirl burners. We found that the swirl number needed for flame stabilization varies only slightly with fuel type, flow velocity, turbulent conditions and burner dimensions (i.e. throat diameter and swirl injection angle).

Swirl Coaxial Injector Testing with LOX/RP-J

NASA Technical Reports Server (NTRS)

Greene, Sandra Elam; Casiano, Matt

2013-01-01

Testing was conducted at NASA fs Marshall Space Flight Center (MSFC) in the fall of 2012 to evaluate the operation and performance of liquid oxygen (LOX) and kerosene (RP ]1) in an existing swirl coaxial injector. While selected Russian engines use variations of swirl coaxial injectors, component level performance data has not been readily available, and all previously documented component testing at MSFC with LOX/RP ]1 had been performed using a variety of impinging injector designs. Impinging injectors have been adequate for specific LOX/RP ]1 engine applications, yet swirl coaxial injectors offer easier fabrication efforts, providing cost and schedule savings for hardware development. Swirl coaxial elements also offer more flexibility for design changes. Furthermore, testing with LOX and liquid methane propellants at MSFC showed that a swirl coaxial injector offered improved performance compared to an impinging injector. So, technical interest was generated to see if similar performance gains could be achieved with LOX/RP ]1 using a swirl coaxial injector. Results would allow such injectors to be considered for future engine concepts that require LOX/RP ]1 propellants. Existing injector and chamber hardware was used in the test assemblies. The injector had been tested in previous programs at MSFC using LOX/methane and LOX/hydrogen propellants. Minor modifications were made to the injector to accommodate the required LOX/RP ]1 flows. Mainstage tests were performed over a range of chamber pressures and mixture ratios. Additional testing included detonated gbombs h for stability data. Test results suggested characteristic velocity, C*, efficiencies for the injector were 95 ]97%. The injector also appeared dynamically stable with quick recovery from the pressure perturbations generated in the bomb tests.

Aero-acoustics of Drag Generating Swirling Exhaust Flows

NASA Technical Reports Server (NTRS)

Shah, P. N.; Mobed, D.; Spakovszky, Z. S.; Brooks, T. F.; Humphreys, W. M. Jr.

2007-01-01

Aircraft on approach in high-drag and high-lift configuration create unsteady flow structures which inherently generate noise. For devices such as flaps, spoilers and the undercarriage there is a strong correlation between overall noise and drag such that, in the quest for quieter aircraft, one challenge is to generate drag at low noise levels. This paper presents a rigorous aero-acoustic assessment of a novel drag concept. The idea is that a swirling exhaust flow can yield a steady, and thus relatively quiet, streamwise vortex which is supported by a radial pressure gradient responsible for pressure drag. Flows with swirl are naturally limited by instabilities such as vortex breakdown. The paper presents a first aero-acoustic assessment of ram pressure driven swirling exhaust flows and their associated instabilities. The technical approach combines an in-depth aerodynamic analysis, plausibility arguments to qualitatively describe the nature of acoustic sources, and detailed, quantitative acoustic measurements using a medium aperture directional microphone array in combination with a previously established Deconvolution Approach for Mapping of Acoustic Sources (DAMAS). A model scale engine nacelle with stationary swirl vanes was designed and tested in the NASA Langley Quiet Flow Facility at a full-scale approach Mach number of 0.17. The analysis shows that the acoustic signature is comprised of quadrupole-type turbulent mixing noise of the swirling core flow and scattering noise from vane boundary layers and turbulent eddies of the burst vortex structure near sharp edges. The exposed edges are the nacelle and pylon trailing edge and the centerbody supporting the vanes. For the highest stable swirl angle setting a nacelle area based drag coefficient of 0.8 was achieved with a full-scale Overall Sound Pressure Level (OASPL) of about 40dBA at the ICAO approach certification point.

Low coke fuel injector for a gas turbine engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, J.R.

This patent describes a gas turbine carbureting device for disposal in a down-stream flowing compressor discharge air flow. It comprises: a spin chamber defined by a generally annular housing including a closed forward end having a continuous unobstructed inner surface and an open aft end wherein the forward end is upstream of the aft end with respect tot he compressor discharge airflow; at least one exhaust tube having an inlet disposed within the spin chamber wherein the exhaust tube is radially spaced apart from the annular housing and which together with the annular housing forms at least in part amore » first annular air passage leading to the forward end; the housing having a fuel entrance and a swirling air entrance to the first annular air passage and spaced axially apart from each other, and wherein the swirling air entrance and fuel entrance are downstream of the closer forward end with respect to the compressor discharge flow; and wherein the first air passage is formed for flowing swirling air from the swirling air passage to the aft end in an upstream direction with respect to the compressor discharge flow and the exhaust tube inlet is disposed within the swirl chamber so as to reverse the axial direction of the swirling air off the forward end from an upstream direction to a downstream direction through the exhaust tube.« less

Combustion behaviors of GO2/GH2 swirl-coaxial injector using non-intrusive optical diagnostics

NASA Astrophysics Data System (ADS)

GuoBiao, Cai; Jian, Dai; Yang, Zhang; NanJia, Yu

2016-06-01

This research evaluates the combustion behaviors of a single-element, swirl-coaxial injector in an atmospheric combustion chamber with gaseous oxygen and gaseous hydrogen (GO2/GH2) as the propellants. A brief simulated flow field schematic comparison between a shear-coaxial injector and the swirl-coaxial injector reveals the distribution characteristics of the temperature field and streamline patterns. Advanced optical diagnostics, i.e., OH planar laser-induced fluorescence and high-speed imaging, are simultaneously employed to determine the OH radical spatial distribution and flame fluctuations, respectively. The present study focuses on the flame structures under varying O/F mixing ratios and center oxygen swirl intensities. The combined use of several image-processing methods aimed at OH instantaneous images, including time-averaged, root-mean-square, and gradient transformation, provides detailed information regarding the distribution of the flow field. The results indicate that the shear layers anchored on the oxygen injector lip are the main zones of chemical heat release and that the O/F mixing ratio significantly affects the flame shape. Furthermore, with high-speed imaging, an intuitionistic ignition process and several consecutive steady-state images reveal that lean conditions make it easy to drive the combustion instabilities and that the center swirl intensity has a moderate influence on the flame oscillation strength. The results of this study provide a visualized analysis for future optimal swirl-coaxial injector designs.

Investigation of turbulent swirling jet-flames by PIV / OH PLIF / HCHO PLIF

NASA Astrophysics Data System (ADS)

Lobasov, A. S.; Chikishev, L. M.

2018-03-01

The present paper reports on the investigation of fuel-lean and fuel-rich turbulent combustion in a high-swirl jet. Swirl rate of the flow exceeded a critical value for breakdown of the swirling jet’s vortex core and formation of the recirculation zone at the jet axis. The measurements were performed by the stereo PIV, OH PLIF and HCHO PLIF techniques, simultaneously. The Reynolds number based on the flow rate and viscosity of the air was fixed as 5 000 (the bulk velocity was U 0 = 5 m/s). Three cases of the equivalence ratio ϕ of the mixture issuing from the nozzle-burner were considered, viz., 0.7, 1.4 and 2.5. The latter case corresponded to a lifted flame of fuel-rich swirling jet flow, partially premixed with the surrounding air. In all cases the flame front was subjected to deformations due to large-scale vortices, which rolled-up in the inner (around the central recirculation zone) and outer (between the annular jet core and surrounding air) mixing layers.

Mixing Characteristics of Coaxial Injectors at High Gas to Liquid Momentum Ratios

NASA Technical Reports Server (NTRS)

Strakey, P. A.; Talley, D. G.; Hutt, J. J.

1999-01-01

A study of the spray of a swirl coaxial gas-liquid injector operating at high gas to liquid momentum ratios is reported. Mixing and droplet size characteristics of the swirl injector are also compared to a shear coaxial injector, currently being used in the Space Shuttle Main Engine fuel preburner. The injectors were tested at elevated chamber pressures using water as a LOX simulant and nitrogen and helium as gaseous hydrogen simulants. The elevated chamber pressure allowed for matching of several of the preburner injector conditions including; gas to liquid momentum ratio, density ratio and Mach number. Diagnostic techniques used to characterize the spray included; strobe back-light imaging, laser sheet spray imaging, mechanical patternation, and a phase Doppler interferometry. Results thus far indicate that the radial spreading of the swirl coaxial spray is much less than was reported in previous studies of swirl injectors operating at atmospheric back-pressure. The swirl coaxial spray does, however, exhibit a smaller overall droplet size which may be interpreted as an increase in local mixing.

Numerical study of gravity effects on phase separation in a swirl chamber.

PubMed

Hsiao, Chao-Tsung; Ma, Jingsen; Chahine, Georges L

2016-01-01

The effects of gravity on a phase separator are studied numerically using an Eulerian/Lagrangian two-phase flow approach. The separator utilizes high intensity swirl to separate bubbles from the liquid. The two-phase flow enters tangentially a cylindrical swirl chamber and rotate around the cylinder axis. On earth, as the bubbles are captured by the vortex formed inside the swirl chamber due to the centripetal force, they also experience the buoyancy force due to gravity. In a reduced or zero gravity environment buoyancy is reduced or inexistent and capture of the bubbles by the vortex is modified. The present numerical simulations enable study of the relative importance of the acceleration of gravity on the bubble capture by the swirl flow in the separator. In absence of gravity, the bubbles get stratified depending on their sizes, with the larger bubbles entering the core region earlier than the smaller ones. However, in presence of gravity, stratification is more complex as the two acceleration fields - due to gravity and to rotation - compete or combine during the bubble capture.

On the prediction of free turbulent jets with swirl using a quadratic pressure-strain model

NASA Technical Reports Server (NTRS)

Younis, Bassam A.; Gatski, Thomas B.; Speziale, Charles G.

1994-01-01

Data from free turbulent jets both with and without swirl are used to assess the performance of the pressure-strain model of Speziale, Sarkar and Gatski which is quadratic in the Reynolds stresses. Comparative predictions are also obtained with the two versions of the Launder, Reece and Rodi model which are linear in the same terms. All models are used as part of a complete second-order closure based on the solution of differential transport equations for each non-zero component of the Reynolds stress tensor together with an equation for the scalar energy dissipation rate. For non-swirling jets, the quadratic model underestimates the measured spreading rate of the plane jet but yields a better prediction for the axisymmetric case without resolving the plane jet/round jet anomaly. For the swirling axisymmetric jet, the same model accurately reproduces the effects of swirl on both the mean flow and the turbulence structure in sharp contrast with the linear models which yield results that are in serious error. The reasons for these differences are discussed.

World of Swirl

NASA Image and Video Library

2007-01-15

The clouds of Saturn swirl, billow and merge. These bands are layered into stratified cloud decks consisting of droplets of ammonia, ammonium hydrosulfide and water set aloft in a sea of hydrogen and helium

Swirling flow in a model of the carotid artery: Numerical and experimental study

NASA Astrophysics Data System (ADS)

Kotmakova, Anna A.; Gataulin, Yakov A.; Yukhnev, Andrey D.

2018-05-01

The present contribution is aimed at numerical and experimental study of inlet swirling flow in a model of the carotid artery. Flow visualization is performed both with the ultrasound color Doppler imaging mode and with CFD data postprocessing of swirling flows in a carotid artery model. Special attention is paid to obtaining data for the secondary motion in the internal carotid artery. Principal errors of the measurement technique developed are estimated using the results of flow calculations.

An Example for Integrated Gas Turbine Engine Testing and Analysis Using Modeling and Simulation

DTIC Science & Technology

2006-12-01

USAF Academy in a joint test and analysis effort of the F109 turbofan engine. This process uses a swirl investigation as a vehicle to exercise and...test and analysis effort of the F109 turbofan engine. This process uses a swirl investigation as a vehicle to exercise and demonstrate the approach...test and analysis effort of the F109 turbofan engine, an effort which uses a swirl investigation as a vehicle to exercise and demonstrate the

The effect of fuel/air mixer design parameters on the continuous and discrete phase structure in the reaction-stabilizing region

NASA Astrophysics Data System (ADS)

Ateshkadi, Arash

The demands on current and future aero gas turbine combustors are demanding a greater insight into the role of the injector/dome design on combustion performance. The structure of the two-phase flow and combustion performance associated with practical injector/dome hardware is thoroughly investigated. A spray injector with two radial inflow swirlers was custom-designed to maintain tight tolerances and strict assembly protocol to isolate the sensitivity of performance to hardware design. The custom set is a unique modular design that (1) accommodates parametric variation in geometry, (2) retains symmetry, and (3) maintains effective area. Swirl sense and presence of a venturi were found to be the most influential on fuel distribution and Lean Blowout. The venturi acts as a fuel-prefilming surface and constrains the highest fuel mass concentration to an annular ring near the centerline. Co-swirl enhances the radial dispersion of the continuous phase and counter-swirl increases the level of mixing that occurs in the downstream region of the mixer. The smallest drop size distributions were found to occur with the counter-swirl configuration with venturi. In the case of counter-swirl without venturi the high concentration of fluid mass is found in the center region of the flow. The Lean Blowout (LBO) equivalence ratio was lower for counter-swirl due to the coupling of the centerline recirculation zone with the location of high fuel concentration emanating from smaller droplets. In the co-swirl configuration a more intense reaction was found near the mixer exit leading to the lowest concentration of NOx, CO and UHC. An LBO model with good agreement to the measured values was developed that related, for the first time, specific hardware parameters and operating condition to stability performance. A semi-analytical model, which agreed best with co-swirl configurations, was modified and used to describe the axial velocity profile downstream of the mixer exit. The development of these two models exemplifies the use of mathematical expressions to guide the design and development procedure for mixer geometry that meet the stringent demands on increasing combustion performance.

Associations between neighbourhood and household environmental variables and fruit consumption: exploration of mediation by individual cognitions and habit strength in the GLOBE study.

PubMed

Tak, Nannah I; te Velde, Saskia J; Kamphuis, Carlijn Bm; Ball, Kylie; Crawford, David; Brug, Johannes; van Lenthe, Frank J

2013-03-01

The present study examined associations of several home and neighbourhood environmental variables with fruit consumption and explored whether these associations were mediated by variables derived from the Theory of Planned Behaviour (TPB) and by habit strength. Data of the Dutch GLOBE study on household and neighbourhood environment, fruit intake and related factors were used, obtained by self-administered questionnaires (cross-sectional), face-to-face interviews and audits. The city of Eindhoven in the Netherlands Adults (n 333; mean age 58 years, 54% female). Multiple mediation analyses were conducted using regression analyses to assess the association between environmental variables and fruit consumption, as well as mediation of these associations by TPB variables and by habit strength. Intention, perceived behaviour control, subjective norm and habit strength were associated with fruit intake. None of the neighbourhood environmental variables was directly or indirectly associated with fruit intake. The home environmental variable 'modelling behaviour by family members' was indirectly, but not directly, associated with fruit intake. Habit strength and perceived behaviour control explained most of the mediated effect (71.9%). Modelling behaviour by family members was indirectly associated with fruit intake through habit strength and perceived behaviour control. None of the neighbourhood variables was directly or indirectly, through any of the proposed mediators, associated with adult fruit intake. These findings suggest that future interventions promoting fruit intake should address a combination of the home environment (especially modelling behaviour by family members), TPB variables and habit strength for fruit intake.

Ultralean low swirl burner

DOEpatents

Cheng, R.K.

1998-04-07

A novel burner and burner method has been invented which burns an ultra lean premixed fuel-air mixture with a stable flame. The inventive burning method results in efficient burning and much lower emissions of pollutants such as oxides of nitrogen than previous burners and burning methods. The inventive method imparts weak swirl (swirl numbers of between about 0.01 to 3.0) on a fuel-air flow stream. The swirl, too small to cause recirculation, causes an annulus region immediately inside the perimeter of the fuel-air flow to rotate in a plane normal to the axial flow. The rotation in turn causes the diameter of the fuel-air flow to increase with concomitant decrease in axial flow velocity. The flame stabilizes where the fuel-air mixture velocity equals the rate of burning resulting in a stable, turbulent flame. 11 figs.

Ultralean low swirl burner

DOEpatents

Cheng, Robert K.

1998-01-01

A novel burner and burner method has been invented which burns an ultra lean premixed fuel-air mixture with a stable flame. The inventive burning method results in efficient burning and much lower emissions of pollutants such as oxides of nitrogen than previous burners and burning methods. The inventive method imparts weak swirl (swirl numbers of between about 0.01 to 3.0) on a fuel-air flow stream. The swirl, too small to cause recirculation, causes an annulus region immediately inside the perimeter of the fuel-air flow to rotate in a plane normal to the axial flow. The rotation in turn causes the diameter of the fuel-air flow to increase with concomitant decrease in axial flow velocity. The flame stabilizes where the fuel-air mixture velocity equals the rate of burning resulting in a stable, turbulent flame.

Dependence of energy characteristics of ascending swirling air flow on velocity of vertical blowing

NASA Astrophysics Data System (ADS)

Volkov, R. E.; Obukhov, A. G.; Kutrunov, V. N.

2018-05-01

In the model of a compressible continuous medium, for the complete Navier-Stokes system of equations, an initial boundary problem is proposed that corresponds to the conducted and planned experiments and describes complex three-dimensional flows of a viscous compressible heat-conducting gas in ascending swirling flows that are initiated by a vertical cold blowing. Using parallelization methods, three-dimensional nonstationary flows of a polytropic viscous compressible heat-conducting gas are constructed numerically in different scaled ascending swirling flows under the condition when gravity and Coriolis forces act. With the help of explicit difference schemes and the proposed initial boundary conditions, approximate solutions of the complete system of Navier-Stokes equations are constructed as well as the velocity and energy characteristics of three-dimensional nonstationary gas flows in ascending swirling flows are determined.

Factors influencing the effective spray cone angle of pressure-swirl atomizers

NASA Astrophysics Data System (ADS)

Chen, S. K.; Lefebvre, A. H.; Rollbuhler, J.

1992-01-01

The spray cone angles produced by several simplex pressure-swirl nozzles are examined using three liquids whose viscosities range from 0.001 to 0.012 kg/ms (1 to 12 cp). Measurements of both the visible spray cone angle and the effective spray cone angle are carried out over wide ranges of injection pressure and for five different values of the discharge orifice length/diameter ratio. The influence of the number of swirl chamber feed slots on spray cone angle is also examined. The results show that the spray cone angle widens with increase in injection pressure but is reduced by increases in liquid viscosity and/or discharge orifice length/diameter ratio. Variation in the number of swirl chamber feed slots between one and three has little effect on the effective spray cone angle.

Experimental investigation of atomization characteristics of swirling spray by ADN gelled propellant

NASA Astrophysics Data System (ADS)

Guan, Hao-Sen; Li, Guo-Xiu; Zhang, Nai-Yuan

2018-03-01

Due to the current global energy shortage and increasingly serious environmental issues, green propellants are attracting more attention. In particular, the ammonium dinitramide (ADN)-based monopropellant thruster is gaining world-wide attention as a green, non-polluting and high specific impulse propellant. Gel propellants combine the advantages of liquid and solid propellants, and are becoming popular in the field of spaceflight. In this paper, a swirling atomization experimental study was carried out using an ADN aqueous gel propellant under different injection pressures. A high-speed camera and a Malvern laser particle size analyzer were used to study the spray process. The flow coefficient, cone angle of swirl atomizing spray, breakup length of spray membrane, and droplet size distribution were analyzed. Furthermore, the effects of different injection pressures on the swirling atomization characteristics were studied.

Mean flowfields in axisymmetric combustor geometries with swirl

NASA Astrophysics Data System (ADS)

Rhode, D. L.; Lilley, D. G.; McLaughlin, D. K.

1982-01-01

Six flowfield configurations are investigated with sidewall angles of 90 and 45 deg, and swirl vane angles of 0, 45, and 70 deg. It is found that central recirculation zones occur for the swirling flow cases investigated, which extend from the inlet to x/D = 1.7, where x is the axial polar coordinate, and D is the test section diameter. Five-hole pitot probe pressure measurements are used to determine time-mean velocities, and corresponding flow situations are predicted and compared to results of experimental data. Excellent agreement is found for the nonswirling flow, although poor agreement is found for swirling flow cases, especially near the inlet. The discrepancy is attributed to the lack of realism in the turbulence model, and/or to inaccurate specification of time-mean velocity and turbulence energy distributions at the inlet.

Wind tunnel performance results of swirl recovery vanes as tested with an advanced high speed propeller

NASA Technical Reports Server (NTRS)

Gazzaniga, John A.; Rose, Gayle E.

1992-01-01

Tests of swirl recovery vanes designed for use in conjunction with advanced high speed propellers were carried out at the NASA Lewis Research Center. The eight bladed 62.23 cm vanes were tested with a 62.23 cm SR = 7A high speed propeller in the NASA Lewis 2.44 x 1.83 m Supersonic Wind Tunnel for a Mach number range of 0.60 to 0.80. At the design operating condition for cruise of Mach 0.80 at an advance ratio of 3.26, the vane contribution to the total efficiency approached 2 percent. At lower off-design Mach numbers, the vane efficiency is even higher, approaching 4.5 percent for the Mach 0.60 condition. Use of the swirl recovery vanes essentially shifts the peak of the high speed propeller efficiency to a higher operating speed. This allows a greater degree of freedom in the selection of rpm over a wider operating range. Another unique result of the swirl recovery vane configuration is their essentially constant torque split between the propeller and the swirl vanes over a wide range of operating conditions for the design vane angle.

Test Results for Rotordynamic Coefficients of the SSME HPOTP Turbine Interstage Seal with Two Swirl Brakes

NASA Technical Reports Server (NTRS)

Childs, Dara W.; Baskharone, Erian; Ramsey, Christopher

1991-01-01

Test results are presented for the HPOTP Turbine Interstage Seal with both the current and an alternate, aerodynamically designed, swirl brake. Tests were conducted at speeds out to 16,000 rpm, supply pressures up to 18.3 bars, and the following three inlet tangential velocity conditions: (1) no preswirl; (2) intermediate preswirl in the direction of rotation; and (3) high preswirl in the direction of rotation. The back pressure can be controlled independently and was varied to yield the following four pressure ratios: 0.4, 0.45, 0.56, and 0.67. The central and simplest conclusion to be obtained from the test series is that the alternate swirl brake consistently outperforms the current swirl brake in terms of stability performance. The alternate swirl brake's whirl frequency ratio was generally about one half or less than corresponding values for the current design. In many cases, the alternate design yielded negative whirl frequency ratio values in comparison to positive values for the current design. The alternate design can be directly substituted into the space currently occupied by the current design. There is no change in leakage performance.

Some effects of swirl on turbulent mixing and combustion

NASA Technical Reports Server (NTRS)

Rubel, A.

1972-01-01

A general formulation of some effects of swirl on turbulent mixing is given. The basis for the analysis is that momentum transport is enhanced by turbulence resulting from rotational instability of the fluid field. An appropriate form for the turbulent eddy viscosity is obtained by mixing length type arguments. The result takes the form of a corrective factor that is a function of the swirl and acts to increase the eddy viscosity. The factor is based upon the initial mixing conditions implying that the rotational turbulence decays in a manner similar to that of free shear turbulence. Existing experimental data for free jet combustion are adequately matched by using the modifying factor to relate the effects of swirl on eddy viscosity. The model is extended and applied to the supersonic combustion of a ring jet of hydrogen injected into a constant area annular air stream. The computations demonstrate that swirling the flow could: (1) reduce the burning length by one half, (2) result in more uniform burning across the annulus width, and (3) open the possibility of optimization of the combustion characteristics by locating the fuel jet between the inner wall and center of the annulus width.

Mechanisms of Exhaust Pollutants and Plume Formation in Continuous Combustion.

DTIC Science & Technology

1984-06-01

device. 4.1.3 Dilute Swirl Combustor (DSC) A swirl-stabilized geometry was developed to address the deficiencies observed with the swirl CBC geometry and...certain deficiencies were apparent in the ability of the model to predict experimental trends. For example: (1) The velocity profiles (Figure lOa) show that...25,000 Re - 50,000 HDF LA 1.1 0.55 Prediction 1.2 0.71 Flow Visualization 0.92 0.66 0 LCF LA 1.2 0.60 Prediction 1.3 0.70 5 J~55 -* - *7 2-- tK2

Deep cytoplasmic rearrangements in axis-respecified Xenopus embryos

NASA Technical Reports Server (NTRS)

Denegre, J. M.; Danilchik, M. V.

1993-01-01

In fertilized eggs of the frog Xenopus, the vegetal yolk mass rotates away from the future dorsal side (J. P. Vincent and J. Gerhart, 1987, Dev. Biol. 123, 526-539), and a major rearrangement of the deep animal hemisphere cytoplasm produces a characteristic swirl in the prospective dorsal side (M. V. Danilchik and J. M. Denegre, 1991, Development 111, 845-856). The relationship between this swirl and determination of the dorsal-ventral axis was further investigated by attempting to experimentally separate the positions of the swirl and the dorsal-ventral axis. Eggs were obliquely oriented in the gravity field to respecify the direction of yolk mass rotation and the position of the dorsal-ventral axis. When yolk mass rotation occurred in the absence of a sperm, as in activated eggs, a swirl pattern formed on the side away from which the yolk mass had rotated. In fertilized eggs tipped with the sperm entry point (SEP) down or to the side, swirl patterns were always found to form on the side away from which the yolk mass was displaced. However, in eggs tipped SEP up, in which the yolk mass was forced to rotate away from the SEP, more complicated rearrangements were observed in addition to the rotation-oriented swirl. Because the direction of yolk mass rotation was found to be influenced by both gravity and the actual position of the SEP in obliquely oriented eggs (SEP to the side), such complicated rearrangement patterns may result from opposing forces generated by both yolk mass rotation and the expanding sperm aster. Thus, except in cases in which the influences of SEP position and unit gravity opposed each other, it was not possible to experimentally separate the position of the deep cytoplasmic swirl from the direction of yolk mass rotation, and therefore the position of the prospective dorsal side.

Azimuthal swirl in liquid metal electrodes and batteries

NASA Astrophysics Data System (ADS)

Ashour, Rakan; Kelley, Douglas

2016-11-01

Liquid metal batteries consist of two molten metals with different electronegativity separated by molten salt. In these batteries, critical performance related factors such as the limiting current density are governed by fluid mixing in the positive electrode. In this work we present experimental results of a swirling flow in a layer of molten lead-bismuth alloy driven by electrical current. Using in-situ ultrasound velocimetery, we show that poloidal circulation appears at low current density, whereas azimuthal swirl becomes dominant at higher current density. The presence of thermal gradients produces buoyant forces, which are found to compete with those produced by current injection. Taking the ratio of the characteristic electromagnetic to buoyant flow velocity, we are able to predict the current density at which the flow becomes electromagnetically driven. Scaling arguments are also used to show that swirl is generated through self-interaction between the electrical current in the electrode with its own magnetic field.

Sheet, ligament and droplet formation in swirling primary atomization

NASA Astrophysics Data System (ADS)

Shao, Changxiao; Luo, Kun; Chai, Min; Fan, Jianren

2018-04-01

We report direct numerical simulations of swirling liquid atomization to understand the physical mechanism underlying the sheet breakup of a non-turbulent liquid swirling jet which lacks in-depth investigation. The volume-of-fluid (VOF) method coupled with adapted mesh refinement (AMR) technique in GERRIS code is employed in the present simulation. The mechanisms of sheet, ligament and droplet formation are investigated. It is observed that the olive-shape sheet structure is similar to the experimental result qualitatively. The numerical results show that surface tension, pressure difference and swirling effect contribute to the contraction and extension of liquid sheet. The ligament formation is partially at the sheet rim or attributed to the extension of liquid hole. Especially, the movement of hairpin vortex exerts by an anti-radial direction force to the sheet surface and leads to the sheet thinness. In addition, droplet formation is attributed to breakup of ligament and central sheet.

Characteristics of inhomogeneous jets in confined swirling air flows

NASA Technical Reports Server (NTRS)

So, R. M. C.; Ahmed, S. A.

1984-01-01

An experimental program to study the characteristics of inhomogeneous jets in confined swirling flows to obtain detailed and accurate data for the evaluation and improvement of turbulent transport modeling for combustor flows is discussed. The work was also motivated by the need to investigate and quantify the influence of confinement and swirl on the characteristics of inhomogeneous jets. The flow facility was constructed in a simple way which allows easy interchange of different swirlers and the freedom to vary the jet Reynolds number. The velocity measurements were taken with a one color, one component DISA Model 55L laser-Doppler anemometer employing the forward scatter mode. Standard statistical methods are used to evaluate the various moments of the signals to give the flow characteristics. The present work was directed at the understanding of the velocity field. Therefore, only velocity and turbulence data of the axial and circumferential components are reported for inhomogeneous jets in confined swirling air flows.

Pollution measurements of a swirl-can combustor

NASA Technical Reports Server (NTRS)

Niedzwiecki, R. W.; Jones, R. E.

1972-01-01

Pollutant levels of oxides of nitrogen, unburned hydrocarbons, and carbon monoxide were measured for an experimental, annular, swirl can combustor. The combustor was 42 inches in diameter, incorporated 120 modules, and was specifically designed for elevated exit temperature performance. Test conditions included combustor inlet temperatures of 600, 900 and 1050 F, inlet pressures of 5 to 6 atmospheres, reference velocities of 69 to 120 feet per second and fuel-air ratios of 0.014 to 0.0695. Tests were also conducted at a simulated engine idle condition. Results demonstrated that swirl can combustors produce oxides of nitrogen levels substantially lower than conventional combustor designs. These reductions are attributed to reduced dwell times resulting from short combustor length, quick mixing of combustion gases with diluent air, and to uniform fuel distributions resulting from the swirl can approach. Radial staging of fuel at idle conditions resulted in increases in combustion efficiencies and corresponding reductions in pollutant levels.

Numerical calculations of turbulent swirling flow

NASA Technical Reports Server (NTRS)

Kubo, I.; Gouldin, F. C.

1974-01-01

Description of a numerical technique for solving axisymmetric, incompressible, turbulent swirling flow problems. Isothermal flow calculations are presented for a coaxial flow configuration of special interest. The calculation results are discussed in regard to their implications for the design of gas turbine combustors.

Propeller swirl effect on single-engine general-aviation aircraft stall-spin tendencies

NASA Technical Reports Server (NTRS)

Katz, Joseph; Feistel, Terry W.

1987-01-01

An investigation is conducted of the effect of a single engine, untapered low wing general aviation aircraft propeller's swirl on the craft's stall pattern. The asymmetrical character of the propeller's swirl can trigger an early stall of one of the wings, aggravating the spin-entry condition. It is shown that the combination of this propeller-induced effect with adverse sideslip can result in large and abrupt changes in the rolling moment, in such conditions as uncoordinated low speed turning maneuvers where the pilot yaws the aircraft with wings level, rather than rolling it.

A numerical and experimental study of confined swirling jets

NASA Technical Reports Server (NTRS)

Nikjooy, M.; Mongia, H. C.; Samuelsen, G. S.; Mcdonell, V. G.

1989-01-01

A numerical and experimental study of a confined strong swirling flow is presented. Detailed velocity measurements are made using a two-component laser Doppler velocimeter (LDV) technique. Computations are performed using a differential second-moment (DSM) closure. The effect of inlet dissipation rate on calculated mean and turbulence fields is investigated. Various model constants are employed in the pressure-strain model to demonstrate their influences on the predicted results. Finally, comparison of the DSM calculations with the algebraic second-monent (ASM) closure results shows that the DSM is better suited for complex swirling flow analysis.

Receptivity of a precessing vortex core to open-loop forcing in a swirling jet and its predictability by linear stability adjoint theory

NASA Astrophysics Data System (ADS)

Müller, Jens; Lückoff, Finn; Oberleithner, Kilian

2017-11-01

The precessing vortex core (PVC) is a dominant coherent structure which occurs in swirling jets such as in swirl-stabilised gas turbine combustors. It stems from a global hydrodynamic instability caused by an internal feedback mechanism within the jet core. In this work, open-loop forcing is applied to a generic non-reacting swirling jet to investigate its receptivity to external actuation regarding lock-in behaviour of the PVC for different streamwise positions and Reynolds numbers. The forcing is periodically exerted by zero net mass flux synthetic jets which are introduced radially through slits inside the duct walls upstream of the swirling jet's exit plane. Time-resolved pressure measurements are conducted to identify the PVC frequency and stereo PIV combined with proper orthogonal decomposition in the duct and free field is used to extract the mean flow and the PVC mode. The data is used in a global linear stability framework to gain the adjoint of the PVC which reveals the regions of highest receptivity to periodic forcing based on mean flow input only. This theoretical receptivity model is compared with the experimentally obtained receptivity results and the validity and applicability of the adjoint model for the prediction of optimal forcing positions is discussed.

Radial lean direct injection burner

DOEpatents

Khan, Abdul Rafey; Kraemer, Gilbert Otto; Stevenson, Christian Xavier

2012-09-04

A burner for use in a gas turbine engine includes a burner tube having an inlet end and an outlet end; a plurality of air passages extending axially in the burner tube configured to convey air flows from the inlet end to the outlet end; a plurality of fuel passages extending axially along the burner tube and spaced around the plurality of air passage configured to convey fuel from the inlet end to the outlet end; and a radial air swirler provided at the outlet end configured to direct the air flows radially toward the outlet end and impart swirl to the air flows. The radial air swirler includes a plurality of vanes to direct and swirl the air flows and an end plate. The end plate includes a plurality of fuel injection holes to inject the fuel radially into the swirling air flows. A method of mixing air and fuel in a burner of a gas turbine is also provided. The burner includes a burner tube including an inlet end, an outlet end, a plurality of axial air passages, and a plurality of axial fuel passages. The method includes introducing an air flow into the air passages at the inlet end; introducing a fuel into fuel passages; swirling the air flow at the outlet end; and radially injecting the fuel into the swirling air flow.

An experimental investigation of gas jets in confined swirling air flow

NASA Technical Reports Server (NTRS)

Mongia, H.; Ahmed, S. A.; Mongia, H. C.

1984-01-01

The fluid dynamics of jets in confined swirling flows which is of importance to designers of turbine combustors and solid fuel ramjets used to power missiles fired from cannons were examined. The fluid dynamics of gas jets of different densities in confined swirling flows were investigated. Mean velocity and turbulence measurements are made with a one color, one component laser velocimeter operating in the forward scatter mode. It is shown that jets in confined flow with large area ratio are highly dissipative which results in both air and helium/air jet centerline velocity decays. For air jets, the jet like behavior in the tube center disappears at about 20 diameters downstream of the jet exit. This phenomenon is independent of the initial jet velocity. The turbulence field at this point also decays to that of the background swirling flow. A jet like behavior in the tube center is noticed even at 40 diameters for the helium/air jets. The subsequent flow and turbulence field depend highly on the initial jet velocity. The jets are fully turbulent, and the cause of this difference in behavior is attributed to the combined action swirl and density difference. This observation can have significant impact on the design of turbine combustors and solid fuel ramjets subject to spin.

Magnetic swirls and associated fast magnetoacoustic kink waves in a solar chromospheric flux tube

NASA Astrophysics Data System (ADS)

Murawski, K.; Kayshap, P.; Srivastava, A. K.; Pascoe, D. J.; Jelínek, P.; Kuźma, B.; Fedun, V.

2018-02-01

We perform numerical simulations of impulsively generated magnetic swirls in an isolated flux tube that is rooted in the solar photosphere. These swirls are triggered by an initial pulse in a horizontal component of the velocity. The initial pulse is launched either (a) centrally, within the localized magnetic flux tube or (b) off-central, in the ambient medium. The evolution and dynamics of the flux tube are described by three-dimensional, ideal magnetohydrodynamic equations. These equations are numerically solved to reveal that in case (a) dipole-like swirls associated with the fast magnetoacoustic kink and m = 1 Alfvén waves are generated. In case (b), the fast magnetoacoustic kink and m = 0 Alfvén modes are excited. In both these cases, the excited fast magnetoacoustic kink and Alfvén waves consist of a similar flow pattern and magnetic shells are also generated with clockwise and counter-clockwise rotating plasma within them, which can be the proxy of dipole-shaped chromospheric swirls. The complex dynamics of vortices and wave perturbations reveals the channelling of sufficient amount of energy to fulfil energy losses in the chromosphere (˜104 W m-1) and in the corona (˜102 W m-1). Some of these numerical findings are reminiscent of signatures in recent observational data.

Fluid-Dynamic Optimal Design of Helical Vascular Graft for Stenotic Disturbed Flow

PubMed Central

Ha, Hojin; Hwang, Dongha; Choi, Woo-Rak; Baek, Jehyun; Lee, Sang Joon

2014-01-01

Although a helical configuration of a prosthetic vascular graft appears to be clinically beneficial in suppressing thrombosis and intimal hyperplasia, an optimization of a helical design has yet to be achieved because of the lack of a detailed understanding on hemodynamic features in helical grafts and their fluid dynamic influences. In the present study, the swirling flow in a helical graft was hypothesized to have beneficial influences on a disturbed flow structure such as stenotic flow. The characteristics of swirling flows generated by helical tubes with various helical pitches and curvatures were investigated to prove the hypothesis. The fluid dynamic influences of these helical tubes on stenotic flow were quantitatively analysed by using a particle image velocimetry technique. Results showed that the swirling intensity and helicity of the swirling flow have a linear relation with a modified Germano number (Gn*) of the helical pipe. In addition, the swirling flow generated a beneficial flow structure at the stenosis by reducing the size of the recirculation flow under steady and pulsatile flow conditions. Therefore, the beneficial effects of a helical graft on the flow field can be estimated by using the magnitude of Gn*. Finally, an optimized helical design with a maximum Gn* was suggested for the future design of a vascular graft. PMID:25360705

Investigations of Multiple Swirl-Venturi Fuel Injector Concepts: Recent Experimental Optical Measurement Results for 1-Point, 7-Point, and 9-Point Configurations

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Anderson, Robert C.; Tedder, Sarah A.; Tacina, Kathleen M.

2015-01-01

This paper presents results obtained during testing in optically-accessible, JP8-fueled, flame tube combustors using swirl-venturi lean direct injection (LDI) research hardware. The baseline LDI geometry has 9 fuel/air mixers arranged in a 3 x 3 array within a square chamber. 2-D results from this 9-element array are compared to results obtained in a cylindrical combustor using a 7-element array and a single element. In each case, the baseline element size remains the same. The effect of air swirler angle, and element arrangement on the presence of a central recirculation zone are presented. Only the highest swirl number air swirler produced a central recirculation zone for the single element swirl-venturi LDI and the 9-element LDI, but that same swirler did not produce a central recirculation zone for the 7-element LDI, possibly because of strong interactions due to element spacing within the array.

Impact of inlet coherent motions on compressor performance

NASA Astrophysics Data System (ADS)

Forlese, Jacopo; Spoleti, Giovanni

2017-08-01

Automotive engine induction systems may be characterized by significant flow angularity and total pressure distortion at the compressor inlet. The impact of the swirl on compressor performance should be quantified to guide the design of the induction systems. In diesel engines, the presence of a valve for flow reduction and control of low pressure EGR recirculation could generate coherent motion and influence the performance of the compressor. Starting from experimental map, the compressor speed-lines have been simulated using a 3D CFD commercial code imposing different concept motion at the inlet. The swirl intensity, the direction and the number of vortices have been imposed in order to taking into account some combinations. Finally, a merit function has been defined to evaluate the performance of the compressor with the defined swirl concepts. The aim of the current work is to obtain an indication on the effect of a swirling motion at the compressor inlet on the engine performance and provide a guideline to the induction system design.

Viscous instabilities in the q-vortex at large swirl numbers

NASA Astrophysics Data System (ADS)

Fabre, David; Jacquin, Laurent

2002-11-01

This comunication deals with the temporal stability of the q-vortex trailing line vortex model. We describe a family of viscous instabilities existing in a range of parameters which is usually assumed to be stable, namely large swirl parameters (q>1.5) and large Reynolds numbers. These instabilities affect negative azimuthal wavenumbers (m < 0) and take the form of centre-modes (i.e. with a structure concentrated along the vortex centerline). They are related to a family of viscous modes described by Stewartson, Ng & Brown (1988) in swirling Poiseuille flow, and are the temporal counterparts of weakly amplified spatial modes recently computed by Olendraru & Sellier (2002). These instabilities are studied numerically using an original and highly accurate Chebyshev collocation method, which allows a mapping of the unstable regions up to Rey 10^6 and q 7. Our results indicate that in the limit of very large Reynolds numbers, trailing vortices are affected by this kind of instabilities whatever the value of the swirl number.

Idle efficiency and pollution results for two-row swirl-can combustors having 72 modules

NASA Technical Reports Server (NTRS)

Biaglow, J. A.; Trout, A. M.

1975-01-01

Two 72-swirl-can-module combustors were investigated in a full annular combustor test facility at engine idle conditions typical of a 30:1 pressure-ratio engine. The effects of radial and circumferential fuel scheduling on combustion efficiency and gaseous pollutants levels were determined. Test conditions were inlet-air temperature, 452 K; inlet total pressure, 34.45 newtons per square centimeter; and reference velocity, 19.5 meters per second. A maximum combustion efficiency of 98.1 percent was achieved by radial scheduling of fuel to the inner row of swirl-can modules. Emission index values were 6.9 for unburned hydrocarbons and 50.6 for carbon monoxide at a fuel-air ratio of 0.0119. Circumferential fuel scheduling of two 90 degree sectors of the swirl-can arrays produced a maximum combustion efficiency of 97.3 percent. The emission index values were 12.0 for unburned hydrocarbons and 69.2 for carbon monoxide at a fuel-air ratio of 0.0130.

Excess Vitamin Intake before Starvation does not Affect Body Mass, Organ Mass, or Blood Variables but Affects Urinary Excretion of Riboflavin in Starving Rats.

PubMed

Moriya, Aya; Fukuwatari, Tsutomu; Shibata, Katsumi

2013-01-01

B-vitamins are important for producing energy from amino acids, fatty acids, and glucose. The aim of this study was to elucidate the effects of excess vitamin intake before starvation on body mass, organ mass, blood, and biological variables as well as on urinary excretion of riboflavin in rats. Adult rats were fed two types of diets, one with a low vitamin content (minimum vitamin diet for optimum growth) and one with a sufficient amount of vitamins (excess vitamin diet). Body mass, organ mass, and blood variables were not affected by excess vitamin intake before starvation. Interestingly, urinary riboflavin excretion showed a different pattern. Urine riboflavin in the excess vitamin intake group declined gradually during starvation, whereas it increased in the low vitamin intake group. Excess vitamin intake before starvation does not affect body mass, organ mass, or blood variables but does affect the urinary excretion of riboflavin in starving rats.

Particle-laden weakly swirling free jets: Measurements and predictions. Ph.D. Thesis - Pennsylvania State Univ.

NASA Technical Reports Server (NTRS)

Bulzan, Daniel L.

1988-01-01

A theoretical and experimental investigation of particle-laden, weakly swirling, turbulent free jets was conducted. Glass particles, having a Sauter mean diameter of 39 microns, with a standard deviation of 15 microns, were used. A single loading ratio (the mass flow rate of particles per unit mass flow rate of air) of 0.2 was used in the experiments. Measurements are reported for three swirl numbers, ranging from 0 to 0.33. The measurements included mean and fluctuating velocities of both phases, and particle mass flux distributions. Measurements were also completed for single-phase non-swirling and swirling jets, as baselines. Measurements were compared with predictions from three types of multiphase flow analysis, as follows: (1) locally homogeneous flow (LHF) where slip between the phases was neglected; (2) deterministic separated flow (DSF), where slip was considered but effects of turbulence/particle interactions were neglected; and (3) stochastic separated flow (SSF), where effects of both interphase slip and turbulence/particle interactions were considered using random sampling for turbulence properties in conjunction with random-walk computations for particle motion. Single-phase weakly swirling jets were considered first. Predictions using a standard k-epsilon turbulence model, as well as two versions modified to account for effects of streamline curvature, were compared with measurements. Predictions using a streamline curvature modification based on the flux Richardson number gave better agreement with measurements for the single-phase swirling jets than the standard k-epsilon model. For the particle-laden jets, the LHF and DSF models did not provide very satisfactory predictions. The LHF model generally overestimated the rate of decay of particle mean axial and angular velocities with streamwise distance, and predicted particle mass fluxes also showed poor agreement with measurements, due to the assumption of no-slip between phases. The DSF model also performed quite poorly for predictions of particle mass flux because turbulent dispersion of the particles was neglected. The SSF model, which accounts for both particle inertia and turbulent dispersion of the particles, yielded reasonably good predictions throughout the flow field for the particle-laden jets.

Test Record of Flight Tests Using Alcohol-to-Jet/JP-8 Blended Fuel

DTIC Science & Technology

2015-09-01

Fuel Pump Corrosion ……………………………………………………………….... 14, 15 2. Pre-Test Coke (carbon) Buildup on Swirl Cups in T55-GA-714A Engines …………………. 16 3...Post-Test Coke (carbon) Buildup on Swirl Cups in T55-GA-714A Engines ………………... 18 5 LIST OF TABLES Table Title Page 1...significant coke (carbon) buildup on the fuel nozzles and swirl cups was observed. The combustor section inspection criteria stipulates that any

Homogeneous solutions of stationary Navier-Stokes equations with isolated singularities on the unit sphere. II. Classification of axisymmetric no-swirl solutions

NASA Astrophysics Data System (ADS)

Li, Li; Li, YanYan; Yan, Xukai

2018-05-01

We classify all (- 1)-homogeneous axisymmetric no-swirl solutions of incompressible stationary Navier-Stokes equations in three dimension which are smooth on the unit sphere minus the south and north poles, parameterizing them as a four dimensional surface with boundary in appropriate function spaces. Then we establish smoothness properties of the solution surface in the four parameters. The smoothness properties will be used in a subsequent paper where we study the existence of (- 1)-homogeneous axisymmetric solutions with non-zero swirl on S2 ∖ { S , N }, emanating from the four dimensional solution surface.

Five-hole pitot probe measurements of swirl, confinement and nozzle effects on confined turbulent flow

NASA Technical Reports Server (NTRS)

Lilley, D. G.; Scharrer, G. L.

1984-01-01

The results of a time-mean flow characterization of nonswirling and swirling inert flows in a combustor are reported. The five-hole pitot probe technique was used in axisymmetric test sections with expansion ratios of 1 and 1.5. A prominent corner recirculation zone identified in nonswirling expanding flows decreased in size with swirling flows. The presence of a downstream nozzle led to an adverse pressure gradient at the wall and a favorable gradient near the centerline. Reducing the expansion ratio reduced the central recirculation length. No significant effect was introduced in the flowfield by a gradual expansion.

Adaptive finite element method for turbulent flow near a propeller

NASA Astrophysics Data System (ADS)

Pelletier, Dominique; Ilinca, Florin; Hetu, Jean-Francois

1994-11-01

This paper presents an adaptive finite element method based on remeshing to solve incompressible turbulent free shear flow near a propeller. Solutions are obtained in primitive variables using a highly accurate finite element approximation on unstructured grids. Turbulence is modeled by a mixing length formulation. Two general purpose error estimators, which take into account swirl and the variation of the eddy viscosity, are presented and applied to the turbulent wake of a propeller. Predictions compare well with experimental measurements. The proposed adaptive scheme is robust, reliable and cost effective.

Magnetic Sorting of the Regolith on the Moon: Lunar Swirls

NASA Astrophysics Data System (ADS)

Pieters, C. M.; Garrick-Bethell, I.; Hemingway, D.

2014-12-01

All of the mysterious albedo features on the Moon called "lunar swirls" are associated with magnetic anomalies, but not all magnetic anomalies are associated with lunar swirls [1]. It is often hypothesized that the albedo markings are tied to immature regolith on the surface, perhaps due to magnetic shielding of the solar wind and prevention of normal space weathering of the soil. Although interaction of the solar wind with the surface at swirls is indeed affected by the local magnetic field [2], this does not appear to result in immature soils on the surface. Calibrated spectra from the Moon Mineralogy Mapper [M3] (in image format) demonstrate that the high albedo markings for swirls are simply not consistent with immature regolith as is now understood from detailed analyses of lunar samples [eg 3]. However, M3 data show that the high albedo features of swirls are distinct and quite different from normal soils (in both the highlands and the mare). They allexhibit a flatter continuum across the near-infrared, but the actual band strength of ferrous minerals shows little (if any) deviation [4]. Recent analyses of magnetic field direction at swirls [5] mimic the observed albedo patterns (horizontal surface fields in bright areas, vertical surface fields in dark lanes). When coupled with the optical properties of magnetic separates of lunar soils [6] and our knowledge that the magnetic component of the soil results from space weathering [3,6], we propose a new and very simple explanation for these enigmatic albedo markings: the lunar swirls result from magnetic sorting of a well developed regolith. With time, normal gardening of the soil over a magnetic anomaly causes some of the dark magnetic component of the soil to be gradually removed from regions (high albedo areas) and accumulated in others (dark lanes). We are modeling predicted sorting rates using realistic rates of dust production. If this mechanism is tenable, only the origin of these magnetic anomalies (their magnitude, size, orientation, and depth) remains to be resolved. Refs: 1. Blewett, DT et al. 2011, JGR , 116. 2. Wieser, M et al. 2010, GRL 37. 3. Taylor, LA et al., 2001 & 2010 JGR; Pieters, CM et al., 2000, MaPS. 4. Pieters et al., 2014, LPSC45 1408. 5. Hemingway, D., and I. Garrick-Bethell 2012, JGR, 117. 6. Adams, JB and TB McCord 1973, 4th LPSC. Cosmochim. Acta, 1, 163-177.

Application of the RNS3D Code to a Circular-Rectangular Transition Duct With and Without Inlet Swirl and Comparison with Experiments

NASA Technical Reports Server (NTRS)

Cavicchi, Richard H.

1999-01-01

Circular-rectangular transition ducts are used between engine exhausts and nozzles with rectangular cross sections that are designed for high performance aircraft. NASA Glenn Research Center has made experimental investigations of a series of circular-rectangular transition ducts to provide benchmark flow data for comparison with numerical calculations. These ducts are all designed with superellipse cross sections to facilitate grid generation. In response to this challenge, the three-dimensional RNS3D code has been applied to one of these transition ducts. This particular duct has a length-to-inlet diameter ratio of 1.5 and an exit-plane aspect ratio of 3.0. The inlet Mach number is 0.35. Two GRC experiments and the code were run for this duct without inlet swirl. One GRC experiment and the code were also run with inlet swirl. With no inlet swirl the code was successful in predicting pressures and secondary flow conditions, including a pair of counter-rotating vortices at both sidewalls of the exit plane. All these phenomena have been reported from the two GRC experiments. However, these vortices were suppressed in the one experiment when inlet swirl was used; whereas the RNS3D code still predicted them. The experiment was unable to provide data near the sidewalls, the very region where the vortices were predicted.

Hydrodynamic Stability Analysis of Multi-jet Effects in Swirling Jet Combustors

NASA Astrophysics Data System (ADS)

Emerson, Benjamin; Lieuwen, Tim

2016-11-01

Many practical combustion devices use multiple swirling jets to stabilize flames. However, much of the understanding of swirling jet dynamics has been generated from experimental and computational studies of single reacting, swirling jets. A smaller body of literature has begun to explore the effects of multi-jet systems and the role of jet-jet interactions on the macro-system dynamics. This work uses local temporal and spatio-temporal stability analyses to isolate the hydrodynamic interactions of multiple reacting, swirling jets, characterized by jet diameter, D, and spacing, L. The results first identify the familiar helical modes in the single jet. Comparison to the multi-jet configuration reveals these same familiar modes simultaneously oscillating in each of the jets. Jet-jet interaction is mostly limited to a spatial synchronization of each jet's oscillations at the jet spacing values analyzed here (L/D =3.5). The presence of multiple jets vs a single jet has little influence on the temporal and absolute growth rates. The biggest difference between the single and multi-jet configurations is the presence of nearly degenerate pairs of hydrodynamic modes in the multi-jet case, with one mode dominated by oscillations in the inner jet, and the other in the outer jets. The close similarity between the single and multi-jet hydrodynamics lends insight into experiments from our group.

Inflow/Outflow Conditions for Unsteady Aerodynamics and Aeroacoustics in Nonuniform Flow

NASA Technical Reports Server (NTRS)

Atassi, Oliver V.; Grady, Joseph E. (Technical Monitor)

2003-01-01

The effect of a nonuniform mean flow on the normal modes; the inflow/outflow nonreflecting boundary conditions; and the sound power are studied. The normal modes in an annular duct are computed using a spectral method in combination with a shooting method. The swirl causes force imbalance which couples the acoustic and vortical modes. The acoustic modes are distinguished from the vortical modes by their large pressure and small vorticity content. The mean swirl also produces a Doppler shift in frequency. This results in more counter-spinning modes cut-on at a given frequency than modes spinning with the swirl. Nonreflecting boundary conditions are formulated using the normal mode solutions. The inflow/outflow boundary conditions are implemented in a linearized Euler scheme and validated by computing the propagation of acoustic and vortical waves in a duct for a variety of swirling mean flows. Numerical results show that the evolution of the vortical disturbances is sensitive to the inflow conditions and the details of the wake excitations. All three components of the wake velocity must be considered to correctly compute the wake evolution and the blade upwash. For high frequencies, the acoustic-vortical mode coupling is weak and a conservation equation for the acoustic energy can be derived. Sound power calculations show significant mean flow swirl effects, but mode interference effects are small.

Exploring individual cognitions, self-regulation skills, and environmental-level factors as mediating variables of two versions of a Web-based computer-tailored nutrition education intervention aimed at adults: A randomized controlled trial.

PubMed

Springvloet, Linda; Lechner, Lilian; Candel, Math J J M; de Vries, Hein; Oenema, Anke

2016-03-01

This study explored whether the determinants that were targeted in two versions of a Web-based computer-tailored nutrition education intervention mediated the effects on fruit, high-energy snack, and saturated fat intake among adults who did not comply with dietary guidelines. A RCT was conducted with a basic (tailored intervention targeting individual cognitions and self-regulation), plus (additionally targeting environmental-level factors), and control group (generic nutrition information). Participants were recruited from the general Dutch adult population and randomly assigned to one of the study groups. Online self-reported questionnaires assessed dietary intake and potential mediating variables (behavior-specific cognitions, action- and coping planning, environmental-level factors) at baseline and one (T1) and four (T2) months post-intervention (i.e. four and seven months after baseline). The joint-significance test was used to establish mediating variables at different time points (T1-mediating variables - T2-intake; T1-mediating variables - T1-intake; T2-mediating variables - T2-intake). Educational differences were examined by testing interaction terms. The effect of the plus version on fruit intake was mediated (T2-T2) by intention and fruit availability at home and for high-educated participants also by attitude. Among low/moderate-educated participants, high-energy snack availability at home mediated (T1-T1) the effect of the basic version on high-energy snack intake. Subjective norm mediated (T1-T1) the effect of the basic version on fat intake among high-educated participants. Only some of the targeted determinants mediated the effects of both intervention versions on fruit, high-energy snack, and saturated fat intake. A possible reason for not finding a more pronounced pattern of mediating variables is that the educational content was tailored to individual characteristics and that participants only received feedback for relevant and not for all assessed mediating variables. Netherlands Trial Registry NTR3396. Copyright © 2015. Published by Elsevier Ltd.

A Simple Tool for Diet Evaluation in Primary Health Care: Validation of a 16-Item Food Intake Questionnaire

PubMed Central

Hemiö, Katri; Pölönen, Auli; Ahonen, Kirsti; Kosola, Mikko; Viitasalo, Katriina; Lindström, Jaana

2014-01-01

Our aim was to validate a 16-item food intake questionnaire (16-FIQ) and create an easy to use method to estimate patients’ nutrient intake in primary health care. Participants (52 men, 25 women) completed a 7-day food record and a 16-FIQ. Food and nutrient intakes were calculated and compared using Spearman correlation. Further, nutrient intakes were compared using kappa-statistics and exact and opposite agreement of intake tertiles. The results indicated that the 16-FIQ reliably categorized individuals according to their nutrient intakes. Methods to estimate nutrient intake based on the answers given in 16-FIQ were created. In linear regression models nutrient intake estimates from the food records were used as the dependent variables and sum variables derived from the 16-FIQ were used as the independent variables. Valid regression models were created for the energy proportion of fat, saturated fat, and sucrose and the amount of fibre (g), vitamin C (mg), iron (mg), and vitamin D (μg) intake. The 16-FIQ is a valid method for estimating nutrient intakes in group level. In addition, the 16-FIQ could be a useful tool to facilitate identification of people in need of dietary counselling and to monitor the effect of counselling in primary health care. PMID:24599042

Variable Cycle Intake for Reverse Core Engine

NASA Technical Reports Server (NTRS)

Chandler, Jesse M (Inventor); Staubach, Joseph B (Inventor); Suciu, Gabriel L (Inventor)

2016-01-01

A gas generator for a reverse core engine propulsion system has a variable cycle intake for the gas generator, which variable cycle intake includes a duct system. The duct system is configured for being selectively disposed in a first position and a second position, wherein free stream air is fed to the gas generator when in the first position, and fan stream air is fed to the gas generator when in the second position.

Investigations of flowfields found in typical combustor geometries

NASA Technical Reports Server (NTRS)

Lilley, D. G.

1982-01-01

Measurements and computations are being applied to an axisymmetric swirling flow, emerging from swirl vanes at angle phi, entering a large chamber test section via a sudden expansion of various side-wall angles alpha. New features are: the turbulence measurements are being performed on swirling as well as nonswirling flow; and all measurements and computations are also being performed on a confined jet flowfield with realistic downstream blockage. Recent activity falls into three categories: (1) Time-mean flowfield characterization by five-hole pitot probe measurements and by flow visualization; (2) Turbulence measurements by a variety of single- and multi-wire hot-wire probe techniques; and (3) Flowfield computations using the computer code developed during the previous year's research program.

Acoustic relaxation of the hydro-mechanical system under critical expiration of swirl flow

NASA Astrophysics Data System (ADS)

Pozdeeva, I. G.; Mitrofanova, O. V.

2018-03-01

The mechanism of generation of acoustic oscillations associated with the formation of stable vortex structures in the moving fluid was considered for the impact swirl flow. Experimental studies were carried out to determine the relationship between large-scale vortex motion and acoustic effects in hydro-mechanical systems. It was shown that a sharp change of the amplitude-frequency characteristic of the acoustic oscillations of hydro-mechanical system corresponds to the maximal flow rate of the swirl flow. The established connection between the generation of sound waves and geometrical and regime parameters of the hydro-mechanical system formed the basis for the developed method of diagnostics of the processes of vortex formation.

In vitro properties of concentrated canine platelets stored in two additive solutions: a comparative study.

PubMed

Hlavac, N; Lasta, C S; Dalmolin, M L; Lacerda, L A; de Korte, D; Marcondes, N A; Terra, S R; Fernandes, F B; González, F H D

2017-11-15

Platelet transfusion therapy poses many challenges in veterinary clinical practice. Lack of readily available blood donors, short shelf-life, and inability to administer a sufficient number of platelets to meet a dog's transfusion need are the major difficulties encountered. Platelet additive solutions are already in use at American and European human blood banks, showing to be a realistic alternative. This study compares the in vitro platelet function in plasma, Composol, or SSP+ during storage for 13 days. Platelet rich plasma-platelet concentrate with 35% plasma and 65% platelet additive solutions (Composol or SSP+) and a control group (100% plasma) were prepared. Swirling, platelet count, blood gases, metabolic variables, platelet activation markers, and apoptosis markers were analyzed on days 1, 5, 9 and 13. Swirling was well preserved and pH was acceptable (> 6.2) during storage for all platelet additive solutions units until day 9. SSP + units showed more stable pH and metabolic variables until day 13. Platelets in plasma showed higher glucose consumption than in Composol or in SSP+. The platelet additive solutions units showed better platelet metabolism maintenance, reduced glucose consumption and lactate production. The apoptotic markers were still low for 9 days in platelet concentrates with platelet additive solutions, suggesting the possibility to extend the shelf life with the use of SSP+ or Composol. Our findings suggest that the uses of Composol and SSP+ in canine platelet concentrates are potential alternatives in veterinary blood banks.

Turbulent Swirling Flow Downstream of an Abrupt Pipe Expansion -- Modeling and Experimental Measurements.

DTIC Science & Technology

1982-07-01

aerospace engineering um~Ŕ" eqe~vswse 0engiee amp snry stem englnerlag. enI~e so ISaCW , meterI scienc Turbulent Swirling Flow Dowstreas of an Abrupt...With the horizontal test section and circumferentially local measurements, the extent of the influence of gravity -induced convection can be determined

Fuel Injector With Shear Atomizer

NASA Technical Reports Server (NTRS)

Beal, George W.; Mills, Virgil L.; Smith, Durward B., II; Beacom, William F.

1995-01-01

Atomizer for injecting liquid fuel into combustion chamber uses impact and swirl to break incoming stream of fuel into small, more combustible droplets. Slanted holes direct flow of liquid fuel to stepped cylindrical wall. Impact on wall atomizes liquid. Air flowing past vanes entrains droplets of liquid in swirling flow. Fuel injected at pressure lower than customarily needed.

Air pollution from aircraft. [jet exhaust - aircraft fuels/combustion efficiency

NASA Technical Reports Server (NTRS)

Heywood, J. B.; Chigier, N. A.

1975-01-01

A model which predicts nitric oxide and carbon monoxide emissions from a swirl can modular combustor is discussed. A detailed analysis of the turbulent fuel-air mixing process in the swirl can module wake region is reviewed. Hot wire anemometry was employed, and gas sampling analysis of fuel combustion emissions were performed.

Research on wall shear stress considering wall roughness when shear swirling flow vibration cementing

NASA Astrophysics Data System (ADS)

Cui, Zhihua; Ai, Chi; Feng, Fuping

2017-01-01

When shear swirling flow vibration cementing, the casing is revolving periodically and eccentrically, which leads to the annulus fluid in turbulent swirling flow state. The wall shear stress is more than that in laminar flow field when conventional cementing. The paper mainly studied the wall shear stress distribution on the borehole wall when shear swirling flow vibration cementing based on the finite volume method. At the same time, the wall roughness affected and changed the turbulent flow near the borehole wall and the wall shear stress. Based on the wall function method, the paper established boundary conditions considering the wall roughness and derived the formula of the wall shear stress. The results showed that the wall roughness significantly increases the wall shear stress. However, the larger the wall roughness, the greater the thickness of mud cake, which weakening the cementing strength. Considering the effects in a comprehensive way, it is discovered that the particle size of solid phase in drilling fluid is about 0.1 mm to get better cementing quality.

Mass and momentum turbulent transport experiments with confined swirling coaxial jets

NASA Technical Reports Server (NTRS)

Roback, R.; Johnson, B. V.

1983-01-01

Swirling coaxial jets mixing downstream, discharging into an expanded duct was conducted to obtain data for the evaluation and improvement of turbulent transport models currently used in a variety of computational procedures throughout the combustion community. A combination of laser velocimeter (LV) and laser induced fluorescence (LIF) techniques was employed to obtain mean and fluctuating velocity and concentration distributions which were used to derive mass and momentum turbulent transport parameters currently incorporated into various combustor flow models. Flow visualization techniques were also employed to determine qualitatively the time dependent characteristics of the flow and the scale of turbulence. The results of these measurements indicated that the largest momentum turbulent transport was in the r-z plane. Peak momentum turbulent transport rates were approximately the same as those for the nonswirling flow condition. The mass turbulent transport process for swirling flow was complicated. Mixing occurred in several steps of axial and radial mass transport and was coupled with a large radial mean convective flux. Mixing for swirling flow was completed in one-third the length required for nonswirling flow.

Numerical and experimental investigation of conventional and un-conventional preswirl duct for VLCC

NASA Astrophysics Data System (ADS)

Shin, Hyun-Joon; Lee, Jong-Seung; Lee, Kang-Hoon; Han, Myung-Ryun; Hur, Eui-Beom; Shin, Sung-Chul

2013-09-01

This paper shows the study of preswirl duct as an effective energy saving devices that have been devised and reviewed to support the propeller performance, especially for the ship of VLCC with large block coefficients. From the bare hull wake measurements, typical upper/lower asymmetry of hull wake at the propeller disk was found. The 2 kinds of pre-swirl duct, Unconventional half circular duct and Conventional circular pre-swirl duct have been designed and reviewed to recover the loss of propeller running in that condition. The general function of the pre-swirl duct was set to work against this asymmetry of wake and generate pre-swirled flow into the propeller against the propeller rotating direction. The optimum self propulsion tests with various angle configurations were carried out and the best configuration was decided. Accordingly, cavitation test was carried out with best configuration of unconventional half circular duct. The blade surface and tip vortex cavitation behaved smoother when the duct was mounted. The hull pressure amplitudes reflected this difference, so the hull pressure amplitude with duct was smaller than that of without duct.

Explaining the Positive Relationship between Fourth-Grade Children’s Body Mass Index and Energy Intake at School-Provided Meals (Breakfast and Lunch)

PubMed Central

Baxter, Suzanne Domel; Royer, Julie A.; Hitchcock, David B.

2013-01-01

BACKGROUND A positive relationship exists between children’s body mass index (BMI) and energy intake at school-provided meals. To help explain this relationship, we investigated 7 outcome variables concerning aspects of school-provided meals—energy content of items selected, number of meal components selected, number of meal components eaten, amounts eaten of standardized school-meal portions, energy intake from flavored milk, energy intake received in trades, and energy content given in trades. METHODS We observed children in grade 4 (N=465) eating school-provided breakfast and lunch on one to 4 days per child. We measured children’s weight and height. For daily values at school meals, a generalized linear model was fit with BMI (dependent variable) and the 7 outcome variables, sex, and age (independent variables). RESULTS BMI was positively related to amounts eaten of standardized school-meal portions (p < .0001) and increased 8.45 kg/m2 per serving, controlling for other variables in the model. BMI was positively related to energy intake from flavored milk (p = .0041) and increased 0.347 kg/m2 for every 100-kcal consumed. BMI was negatively related to energy intake received in trades (p = .0003) and decreased 0.468 kg/m2 for every 100-kcal received. BMI was not significantly related to 4 outcome variables. CONCLUSIONS Knowing that relationships between BMI and actual consumption, not selection, at school-provided meals explained the (previously found) positive relationship between BMI and energy intake at school-provided meals is helpful for school-based obesity interventions. PMID:23517000

Thermal Ion Transport on the Moon and the Formation of the Lunar Swirls

NASA Technical Reports Server (NTRS)

Keller, John W.; Killen, R. M.; Stubbs, T. J.; Farrell, W. M.; Halekas, J. S.

2011-01-01

The bright "swirl" features observed on the lunar surface are generally associated with crustal magnetic anomalies. Prominent explanations that invoke these fields include: magnetic shielding in the form of a mini-magnetosphere, which impedes space weathering by the solar wind; magnetically controlled dust transport; and cometary or asteroidal impacts, that could result in shock magnetization with concomitant formation of the swirls. Here we consider another possibility in which the ambient magnetic and electric fields can transport and channel secondary ions produced by micrometeorite or solar wind ion impacts. We use a simplified model of the fields, which incorporates a two-dipole magnetic field model for Reiner Gamma, and typical solar wind conditions. We will present preliminarily results suggesting that ions created over significant regions of the lunar surface can be transported under the influence of local and interplanetary electromagnetic fields to narrow areas ncar arcas of high crustal magnetic field strength. The flux of these focused ions may be of sufficient intensity to chemically process (or otherwise bleach) the surface leading to the formation of the high albedo component of the lunar swirls. The theory is appealing since through a lensing effect, it is possible that this flux is sufficient to overcome other space weathering processes which would otherwise tend to erase the features. Also, with relatively low energy ions, and consistent with the observed focusing, the ion gyro radii in the local magnetic fields is small enough to resolve the swirls.

A Computational Fluid Dynamics Study of Swirling Flow Reduction by using Anti-vortex Baffle

NASA Technical Reports Server (NTRS)

Yang, H. Q.; Peugeot, John W.; West, Jeff S..

2013-01-01

An anti-vortex baffle is a liquid propellant management device placed adjacent to an outlet of the propellant tank. Its purpose is to substantially reduce or eliminate the formation of free surface dip and vortex, as well as prevent vapor ingestion into the outlet, as the liquid drains out through the flight. To design an effective anti-vortex baffle, Computational Fluid Dynamic (CFD) simulations were undertaken for the NASA Ares I vehicle LOX tank subjected to the simulated flight loads with and without the anti-vortex baffle. The Six Degree-Of-Freedom (6- DOF) dynamics experienced by the Crew Launch Vehicle (CLV) during ascent were modeled by modifying the momentum equations in a CFD code to accommodate the extra body forces from the maneuvering in a non-inertial frame. The present analysis found that due to large moments, the CLV maneuvering has significant impact on the vortical flow generation inside the tank. Roll maneuvering and side loading due to pitch and yaw are shown to induce swirling flow. The vortical flow due to roll is symmetrical with respect to the tank centerline, while those induced by pitch and yaw maneuverings showed two vortices side by side. The study found that without the anti-vortex baffle, the swirling flow caused surface dip during the late stage of drainage and hence early vapor ingestion. The flow can also be non-uniform in the drainage pipe as the secondary swirling flow velocity component can be as high as 10% of the draining velocity. An analysis of the vortex dynamics shows that the swirling flow in the drainage pipe during the Upper Stage burn is mainly the result of residual vortices inside the tank due to conservation of angular momentum. The study demonstrated that the swirling flow in the drainage pipe can be effectively suppressed by employing the anti-vortex baffle.

A Computational Fluid Dynamics Study of Swirling Flow Reduction by Using Anti-Vortex Baffle

NASA Technical Reports Server (NTRS)

Yang, H. Q.; Peugeot, John W.; West, Jeff S.

2017-01-01

An anti-vortex baffle is a liquid propellant management device placed adjacent to an outlet of the propellant tank. Its purpose is to substantially reduce or eliminate the formation of free surface dip and vortex, as well as prevent vapor ingestion into the outlet, as the liquid drains out through the flight. To design an effective anti-vortex baffle, Computational Fluid Dynamic (CFD) simulations were undertaken for the NASA Ares I vehicle LOX tank subjected to the simulated flight loads with and without the anti-vortex baffle. The Six Degree-Of-Freedom (6-DOF) dynamics experienced by the Crew Launch Vehicle (CLV) during ascent were modeled by modifying the momentum equations in a CFD code to accommodate the extra body forces from the maneuvering in a non-inertial frame. The present analysis found that due to large moments, the CLV maneuvering has a significant impact on the vortical flow generation inside the tank. Roll maneuvering and side loading due to pitch and yaw are shown to induce swirling flow. The vortical flow due to roll is symmetrical with respect to the tank centerline, while those induced by pitch and yaw maneuverings showed two vortices side by side. The study found that without the anti-vortex baffle, the swirling flow caused surface dip during the late stage of drainage and hence early vapor ingestion. The flow can also be non-uniform in the drainage pipe as the secondary swirling flow velocity component can be as high as 10% of the draining velocity. An analysis of the vortex dynamics shows that the swirling flow in the drainage pipe during the Upper Stage burn is mainly the result of residual vortices inside the tank due to the conservation of angular momentum. The study demonstrated that the swirling flow in the drainage pipe can be effectively suppressed by employing the anti-vortex baffle.

Effect of aviation fuel type and fuel injection conditions on the spray characteristics of pressure swirl and hybrid air blast fuel injectors

NASA Astrophysics Data System (ADS)

Feddema, Rick

Feddema, Rick T. M.S.M.E., Purdue University, December 2013. Effect of Aviation Fuel Type and Fuel Injection Conditions on the Spray Characteristics of Pressure Swirl and Hybrid Air Blast Fuel Injectors. Major Professor: Dr. Paul E. Sojka, School of Mechanical Engineering Spray performance of pressure swirl and hybrid air blast fuel injectors are central to combustion stability, combustor heat management, and pollutant formation in aviation gas turbine engines. Next generation aviation gas turbine engines will optimize spray atomization characteristics of the fuel injector in order to achieve engine efficiency and emissions requirements. Fuel injector spray atomization performance is affected by the type of fuel injector, fuel liquid properties, fuel injection pressure, fuel injection temperature, and ambient pressure. Performance of pressure swirl atomizer and hybrid air blast nozzle type fuel injectors are compared in this study. Aviation jet fuels, JP-8, Jet A, JP-5, and JP-10 and their effect on fuel injector performance is investigated. Fuel injector set conditions involving fuel injector pressure, fuel temperature and ambient pressure are varied in order to compare each fuel type. One objective of this thesis is to contribute spray patternation measurements to the body of existing drop size data in the literature. Fuel droplet size tends to increase with decreasing fuel injection pressure, decreasing fuel injection temperature and increasing ambient injection pressure. The differences between fuel types at particular set conditions occur due to differences in liquid properties between fuels. Liquid viscosity and surface tension are identified to be fuel-specific properties that affect the drop size of the fuel. An open aspect of current research that this paper addresses is how much the type of aviation jet fuel affects spray atomization characteristics. Conventional aviation fuel specifications are becoming more important with new interest in alternative fuels. Optical patternation data and line of sight laser diffraction data show that there is significant difference between jet fuels. Particularly at low fuel injection pressures (0.345 MPa) and cold temperatures (-40 C), the patternation data shows that the total surface area in the spray at 38.1 mm from the pressure swirl injector for the JP-10 fuel type is one-sixth the amount of the JP-8. Finally, this study compares the atomizer performance of a pressure swirl nozzle to a hybrid air blast nozzle. The total surface area for both the hybrid air blast nozzle and the pressure swirl nozzle show a similar decline in atomization performance at low fuel injection pressures and cold temperatures. However, the optical patternator radial profile data and the line of sight laser diffraction data show that the droplet size and spray distribution data are less affected by injection conditions and fuel type in the hybrid air blast nozzle, than they are in the pressure swirl nozzle. One explanation is that the aerodynamic forces associated with the swirler on the hybrid air blast nozzle control the distribution droplets in the spray. This is in contrast to the pressure swirl nozzle droplet distribution that is controlled by internal geometry and droplet ballistics.

Associations between Whole-Grain Intake, Psychosocial Variables, and Home Availability among Elementary School Children

ERIC Educational Resources Information Center

Rosen, Renee A.; Burgess-Champoux, Teri L.; Marquart, Len; Reicks, Marla M.

2012-01-01

Objective: Develop, refine, and test psychosocial scales for associations with whole-grain intake. Methods: A cross-sectional survey was conducted in a Minneapolis/St. Paul suburban elementary school with children in fourth through sixth grades (n = 98) and their parents (n = 76). Variables of interest were child whole-grain intake, self-efficacy,…

Associations among sugar sweetened beverage intake, visceral fat, and cortisol awakening response in minority youth

PubMed Central

Shearrer, GE; Daniels, MJ; Toledo-Corral, CM; Weigensberg, MJ; Spruijt-Metz, D; Davis, JN

2016-01-01

Context Abdominal adiposity has long been associated with excess caloric intake possibly resulting from increased psychosocial stress and associated cortisol dysfunction. However, the relationship of sugar-sweetened beverage (SSB) intake specifically with cortisol variability and visceral adipose tissue (VAT) is unknown. Objective To examine the relationships between SSB intake, VAT, and cortisol response in minority youth. Design A cross-sectional analysis. Setting The University of Southern California. Participants 60 overweight/obese Non-Hispanic Black and Hispanic adolescents ages 14–18 years. Main Outcome Measures VAT via Magnet Resonance Imaging (MRI), cortisol awakening response (CAR) via multiple salivary samples, and SSB intake via multiple 24-hour diet recalls. SSB intake was divided into the following: low SSB consumers (< 1 servings per day), medium SSB consumers (≥1 - <2 servings per day), high SSB consumers (≥2 servings per day). Analysis of covariance were run with VAT and CAR as dependent variables and SSB intake categories (independent variable) with the following a priori covariates: sex, Tanner stage, ethnicity, caloric intake, and body mass index. Results The high SSB intake group exhibited a 7% higher VAT compared to the low SSB intake group (β=0.25, CI:(0.03, 0.33), p=0.02). CAR was associated with VAT (β=0.31, CI:(0.01,0.23), p=0.02). The high SSB intake group exhibited 22% higher CAR compared to the low SSB intake group (β=0.30, CI:(0.02,0.48), p=0.04). Conclusion This is the first study exploring the relationship between SSB, VAT, and CAR. SSB consumption appears to be independently associated greater abdominal adiposity and higher morning cortisol variability in overweight and obese minority youth. This study highlights potential targets for interventions specifically to reduce SSB intake in a minority youth population. PMID:27660033

Hydrodynamic conditions in designed spiral photobioreactors.

PubMed

Wu, L B; Li, Z; Song, Y Z

2010-01-01

In this work, a series of spiral tube PBRs were introduced. Flow dynamics of microalgae fluid, light intensity histories of tracked cells and swirl numbers within the spiral PBRs were numerically simulated. Results show that strong swirl motions are formed in the cross-sections along axial coordinate of spiral PBRs, but no such vortice is observed for tubular PBR. The light intensity histories identify that the microalgae cells experience the so-called light/dark cycle, which is necessary to their growth. With high swirl numbers ranging from 0.15 to 0.35, the mixing performances of the spiral tube PBRs are much better than that of tubular PBR, indicating such innovative geometries of spiral tube PBRs may be applicable for large scale commercial cultivation of microalgae in the future.

Combustion efficiency of a premixed continuous flow combustor

NASA Technical Reports Server (NTRS)

Anand, M. S.; Gouldin, F. C.

1985-01-01

Exhaust gas temperature, velocity, and composition measurements at various radial locations at the combustor exit are presented for a swirling-flow continuous combustor of a confined concentric jet configuration operating on premixed propane or methane and air. The main objective of the study is to determine the effect of fuel substitution and of changes in outer flow swirl conditions on the combustor performance. It is found that there is no difference in observed properties for propane and methane firing; the use of either of the fuels results in nearly the same exit temperature and velocity profiles and the same efficiency for a given operating condition. A mechanism for combustion is proposed which explains qualitatively the changes in efficiency and pollutant emissions observed with changing swirl.

Heat transfer simulation of unsteady swirling flow in a vortex tube

NASA Astrophysics Data System (ADS)

Veretennikov, S. V.; Piralishvili, Sh A.; Evdokimov, O. A.; Guryanov, A. I.

2018-03-01

Effectiveness of not-adiabatic vortex tube application in the cooling systems of gas turbine blades depends on characteristics of swirling flows formed in the energy separation chamber. An analysis of the flow structure in the vortex tube channels has shown a presence of a complex three-dimensional spiral vortex, formed under relatively high turbulence intensity and vortex core precession. This indicates the presence of a significant unsteady flow in the energy separation chamber of the vortex tube that has a great influence on convective heat transfer of the swirling flow to the inner surface of tube. The paper contains the results of investigation of gas dynamics and heat transfer in the vortex tube taking into account the flow unsteadiness.

Flow fields behind a variable-area nozzle for radial turbines

NASA Astrophysics Data System (ADS)

Hayami, Hiroshi; Hyun, Yong-Ik; Senoo, Yasutoshi; Yamaguchi, Michiteru

The flow fields behind a variable-area nozzle for radial turbines were measured in detail using a three-hole cobra probe in 15 cases, which are a combination of three nozzle throat areas (0.8, 1.0, and 1.4 times the rated area) and five values of the tip-clearance to blade-height ratio (between 0.0 to 0.099). The flow fields at different tip clearances are presented in contour maps, and the pitch mean values are discussed as spanwise distributions of total pressure loss, flow angle, and radial and tangential velocity components. It is shown that the intensity of swirl behind the nozzle is decreased and the pressure loss is increased with the tip clearance, and the effect is magnified as the blade loading is higher.

Explaining the positive relationship between fourth-grade children's body mass index and energy intake at school-provided meals (breakfast and lunch).

PubMed

Guinn, Caroline H; Baxter, Suzanne D; Royer, Julie A; Hitchcock, David B

2013-05-01

A 2010 publication showed a positive relationship between children's body mass index (BMI) and energy intake at school-provided meals (as assessed by direct meal observations). To help explain that relationship, we investigated 7 outcome variables concerning aspects of school-provided meals: energy content of items selected, number of meal components selected, number of meal components eaten, amounts eaten of standardized school-meal portions, energy intake from flavored milk, energy intake received in trades, and energy content given in trades. Fourth-grade children (N = 465) from Columbia, SC, were observed eating school-provided breakfast and lunch on 1 to 4 days per child. Researchers measured children's weight and height. For daily values at school meals, a generalized linear model was fit with BMI (dependent variable) and the 7 outcome variables, sex, and age (independent variables). BMI was positively related to amounts eaten of standardized school-meal portions (p < .0001) and increased 8.45 kg/m(2) per serving, controlling for other variables in the model. BMI was positively related to energy intake from flavored milk (p = .0041) and increased 0.347 kg/m(2) for every 100 kcal consumed. BMI was negatively related to energy intake received in trades (p = .0003) and decreased 0.468 kg/m(2) for every 100 kcal received. BMI was not significantly related to 4 outcome variables. Knowing that relationships between BMI and actual consumption, not selection, at school-provided meals explained the (previously found) positive relationship between BMI and energy intake at school-provided meals is helpful for school-based obesity interventions. © 2013, American School Health Association.

Multinomial logistic regression modelling of obesity and overweight among primary school students in a rural area of Negeri Sembilan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghazali, Amirul Syafiq Mohd; Ali, Zalila; Noor, Norlida Mohd

Multinomial logistic regression is widely used to model the outcomes of a polytomous response variable, a categorical dependent variable with more than two categories. The model assumes that the conditional mean of the dependent categorical variables is the logistic function of an affine combination of predictor variables. Its procedure gives a number of logistic regression models that make specific comparisons of the response categories. When there are q categories of the response variable, the model consists of q-1 logit equations which are fitted simultaneously. The model is validated by variable selection procedures, tests of regression coefficients, a significant test ofmore » the overall model, goodness-of-fit measures, and validation of predicted probabilities using odds ratio. This study used the multinomial logistic regression model to investigate obesity and overweight among primary school students in a rural area on the basis of their demographic profiles, lifestyles and on the diet and food intake. The results indicated that obesity and overweight of students are related to gender, religion, sleep duration, time spent on electronic games, breakfast intake in a week, with whom meals are taken, protein intake, and also, the interaction between breakfast intake in a week with sleep duration, and the interaction between gender and protein intake.« less

Multinomial logistic regression modelling of obesity and overweight among primary school students in a rural area of Negeri Sembilan

NASA Astrophysics Data System (ADS)

Ghazali, Amirul Syafiq Mohd; Ali, Zalila; Noor, Norlida Mohd; Baharum, Adam

2015-10-01

Multinomial logistic regression is widely used to model the outcomes of a polytomous response variable, a categorical dependent variable with more than two categories. The model assumes that the conditional mean of the dependent categorical variables is the logistic function of an affine combination of predictor variables. Its procedure gives a number of logistic regression models that make specific comparisons of the response categories. When there are q categories of the response variable, the model consists of q-1 logit equations which are fitted simultaneously. The model is validated by variable selection procedures, tests of regression coefficients, a significant test of the overall model, goodness-of-fit measures, and validation of predicted probabilities using odds ratio. This study used the multinomial logistic regression model to investigate obesity and overweight among primary school students in a rural area on the basis of their demographic profiles, lifestyles and on the diet and food intake. The results indicated that obesity and overweight of students are related to gender, religion, sleep duration, time spent on electronic games, breakfast intake in a week, with whom meals are taken, protein intake, and also, the interaction between breakfast intake in a week with sleep duration, and the interaction between gender and protein intake.

The three-dimensional structure of swirl-switching in bent pipe flow

DOE PAGES

Hufnagel, Lorenz; Canton, Jacopo; Örlü, Ramis; ...

2017-11-27

Swirl-switching is a low-frequency oscillatory phenomenon which affects the Dean vortices in bent pipes and may cause fatigue in piping systems. Despite thirty years worth of research, the mechanism that causes these oscillations and the frequencies that characterise them remain unclear. In this paper, we show that a three-dimensional wave-like structure is responsible for the low-frequency switching of the dominant Dean vortex. The present study, performed via direct numerical simulation, focuses on the turbulent flow through amore » $$90^{\\circ }$$pipe bend preceded and followed by straight pipe segments. A pipe with curvature 0.3 (defined as ratio between pipe radius and bend radius) is studied for a bulk Reynolds number $$Re=11\\,700$$, corresponding to a friction Reynolds number $$Re_{\\unicode[STIX]{x1D70F}}\\approx 360$$. Synthetic turbulence is generated at the inflow section and used instead of the classical recycling method in order to avoid the interference between recycling and swirl-switching frequencies. The flow field is analysed by three-dimensional proper orthogonal decomposition (POD) which for the first time allows the identification of the source of swirl-switching: a wave-like structure that originates in the pipe bend. Contrary to some previous studies, the flow in the upstream pipe does not show any direct influence on the swirl-switching modes. Finally, our analysis further shows that a three-dimensional characterisation of the modes is crucial to understand the mechanism, and that reconstructions based on two-dimensional POD modes are incomplete.« less

Lunar Ion Transport Near Magnetic Anomalies: Possible Implications for Swirl Formation

NASA Technical Reports Server (NTRS)

Keller, J. W.; Killen, R. M.; Stubbs, T. J.; Farrell, W. M.; Halekas, J. S.

2011-01-01

The bright swirling features on the lunar surface in areas around the Moon but most prominently at Reiner Gamma, have intrigued scientists for many years. After Apollo and later Lunar Prospector (LP} mapped the Lunar magnetic fields from orbit, it was observed that these features are generally associated with crustal magnetic anomalies. This led researchers to propose a number of explanations for the swirls that invoke these fields. Prominent among these include magnetic shielding in the form of a mini-magnetosphere which impedes space weathering by the solar wind, magnetically controlled dust transport, and cometary or asteroidal impacts that would result in shock magnetization with concomitant formation ofthe swirls. In this presentation, we will consider another possibility, that the ambient magnetic and electric fields can transport and channel secondary ions produced by micrometeorite or solar wind ion impacts. In this scenario, ions that are created in these impacts are under the influence of these fields and can drift for significant distances before encountering the magnetic anomalies when their trajectories are disrupted and concentrated onto nearby areas. These ions may then be responsible for chemical alteration of the surface leading either to a brightening effect or a disruption of space weathering processes. To test this hypothesis we have run ion trajectory simulations that show ions from regions about the magnetic anomalies can be channeled into very small areas near the anomalies and although questions remain as to nature of the mechanisms that could lead to brightening of the surface it appears that the channeling effect is consistent with the existence of the swirls.

The three-dimensional structure of swirl-switching in bent pipe flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hufnagel, Lorenz; Canton, Jacopo; Örlü, Ramis

Swirl-switching is a low-frequency oscillatory phenomenon which affects the Dean vortices in bent pipes and may cause fatigue in piping systems. Despite thirty years worth of research, the mechanism that causes these oscillations and the frequencies that characterise them remain unclear. In this paper, we show that a three-dimensional wave-like structure is responsible for the low-frequency switching of the dominant Dean vortex. The present study, performed via direct numerical simulation, focuses on the turbulent flow through amore » $$90^{\\circ }$$pipe bend preceded and followed by straight pipe segments. A pipe with curvature 0.3 (defined as ratio between pipe radius and bend radius) is studied for a bulk Reynolds number $$Re=11\\,700$$, corresponding to a friction Reynolds number $$Re_{\\unicode[STIX]{x1D70F}}\\approx 360$$. Synthetic turbulence is generated at the inflow section and used instead of the classical recycling method in order to avoid the interference between recycling and swirl-switching frequencies. The flow field is analysed by three-dimensional proper orthogonal decomposition (POD) which for the first time allows the identification of the source of swirl-switching: a wave-like structure that originates in the pipe bend. Contrary to some previous studies, the flow in the upstream pipe does not show any direct influence on the swirl-switching modes. Finally, our analysis further shows that a three-dimensional characterisation of the modes is crucial to understand the mechanism, and that reconstructions based on two-dimensional POD modes are incomplete.« less

Hydromonochord: Visualizing String Vibration by Water Swirls

ERIC Educational Resources Information Center

Sommer, Wilfried; Meier-Boke, Ralf; Meinzer, Nicholas

2010-01-01

The hydromonochord is a horizontal vibrating string that just makes contact with the surface of a water bath. The motion of the string sets up a pattern of swirls on the surface of the water, thus complementing the usual pattern of nodes and antinodes. The device is based on the traditional monochord. A water basin (Fig. 1) has two slits in the…

Influence of upstream disturbance on the draft-tube flow of Francis turbine under part-load conditions

NASA Astrophysics Data System (ADS)

Chen, Ting; Zheng, Xianghao; Zhang, Yu-ning; Li, Shengcai

2018-02-01

Owing to the part-load operations for the enhancement of grid flexibility, the Francis turbine often suffers from severe low-frequency and large-amplitude hydraulic instability, which is mostly pertinent to the highly unsteady swirling vortex rope in the draft tube. The influence of disturbances in the upstream (e.g., large-scale vortex structures in the spiral casing) on the draft-tube vortex flow is not well understood yet. In the present paper, the influence of the upstream disturbances on the vortical flow in the draft tube is studied based on the vortex identification method and the analysis of several important parameters (e.g., the swirl number and the velocity profile). For a small guide vane opening (representing the part-load condition), the vortices triggered in the spiral casing propagate downstream and significantly affect the swirling vortex-rope precession in the draft tube, leading to the changes of the intensity and the processional frequency of the swirling vortex rope. When the guide vane opening approaches the optimum one (representing the full-load condition), the upstream disturbance becomes weaker and thus its influences on the downstream flow are very limited.

Flow Straightener for a Rotating-Drum Liquid Separator

NASA Technical Reports Server (NTRS)

O'Coin, James R.; Converse, David G.; Rethke, Donald W.

2004-01-01

A flow straightener has been incorporated into a rotary liquid separator that originally comprised an inlet tube, a shroud plate, an impeller, an inner drum, an outer drum, a housing, a pitot tube, and a hollow shaft motor. As a consequence of the original geometry of the impeller, shroud, inner drum, and hollow shaft, swirl was created in the airflow inside the hollow shaft during operation. The swirl speed was large enough to cause a significant pressure drop. The flow straightener consists of vanes on the back side of the shroud plate. These vanes compartmentalize the inside of the inner drum in such a way as to break up the flow path and thereby stop the air from swirling; as a result, the air enters the hollow shaft with a predominantly axial velocity instead of a swirl. Tests of the rotary liquid separator at an airflow rate of 10 cu ft/min (0.0047 cu m/s) revealed that the dynamic pressure drop was 8 in. of water (approx.=2 kPa) in the absence of the flow straightener and was reduced to 1 in. of water (approx.=0.25 kPa) in the presence of the flow straightener.

The modified swirl sedimentation tanks for water purification.

PubMed

Ochowiak, Marek; Matuszak, Magdalena; Włodarczak, Sylwia; Ancukiewicz, Małgorzata; Krupińska, Andżelika

2017-03-15

This paper discusses design, evaluation, and application for the use of swirl/vortex technologies as liquid purification system. A study was performed using modified swirl sedimentation tanks. The vortex separators (OW, OWK, OWR and OWKR) have been studied under laboratory conditions at liquid flow rate from 2.8⋅10 -5 to 5.1⋅10 -4 [m 3 /s]. The pressure drop and the efficiency of purification of liquid stream were analyzed. The suspended particles of different diameters were successfully removed from liquid with the application of swirl chambers of proposed constructions. It was found that damming of liquid in the tank increases alongside liquid stream at the inlet and depends on the tank construction. The efficiency of the sedimentation tanks increases alongside the diameters of solid particles and decrease in the liquid flow rate. The best construction proved to be the OWR sedimentation tank due to smallest liquid damming, even at high flow rates, and the highest efficiency of the purification liquid stream for solid particles of the smallest diameter. The proposed solution is an alternative to the classical constructions of sedimentation tanks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Space Weathering Trends (UV and NIR) at Lunar Magnetic Anomalies

NASA Astrophysics Data System (ADS)

Blewett, D. T.; Denevi, B. W.; Cahill, J. T.; Klima, R. L.

2017-12-01

Areas of magnetized crustal rocks on the Moon, known as magnetic anomalies, affect the flux of solar-wind ions that bombard the lunar surface. Hence, magnetically shielded areas could experience a space weathering regime different from the lunar norm. The unusual, high-albedo markings called lunar swirls are collocated with magnetic anomalies. The high albedo in the near-ultraviolet through near-infrared is consistent with the presence of material that is less weathered than that found in mature, non-shielded areas. We have undertaken an analysis of spectral trends associated with swirls in order to gain further insight into the nature and origin of these features. We examine swirls in the near-ultraviolet (Lunar Reconnaissance Orbiter LROC-WAC) and near-infrared (Chandrayaan Moon Mineralogy Mapper and Kaguya Spectral Profiler). We find that relative to the normal weathering trend, the swirls have a steeper NIR continuum slope (i.e., the continuum is redder than expected for their albedo) and steeper UV slope (i.e., greater UV drop-off than expected for their albedo). These trends can be understood in terms of differing relative abundances of microphase and nanophase metallic iron weathering products.

Large-scale vortex structures and local heat release in lean turbulent swirling jet-flames under vortex breakdown conditions

NASA Astrophysics Data System (ADS)

Chikishev, Leonid; Lobasov, Aleksei; Sharaborin, Dmitriy; Markovich, Dmitriy; Dulin, Vladimir; Hanjalic, Kemal

2017-11-01

We investigate flame-flow interactions in an atmospheric turbulent high-swirl methane/air lean jet-flame at Re from 5,000 to 10,000 and equivalence ratio below 0.75 at the conditions of vortex breakdown. The focus is on the spatial correlation between the propagation of large-scale vortex structures, including precessing vortex core, and the variations of the local heat release. The measurements are performed by planar laser-induced fluorescence of hydroxyl and formaldehyde, applied simultaneously with the stereoscopic particle image velocimetry technique. The data are processed by the proper orthogonal decomposition. The swirl rate exceeded critical value for the vortex breakdown resulting in the formation of a processing vortex core and secondary helical vortex filaments that dominate the unsteady flow dynamics both of the non-reacting and reacting jet flows. The flame front is located in the inner mixing layer between the recirculation zone and the annular swirling jet. A pair of helical vortex structures, surrounding the flame, stretch it and cause local flame extinction before the flame is blown away. This work is supported by Russian Science Foundation (Grant No 16-19-10566).

Computational fluid dynamics assessment: Volume 2, Isothermal simulations of the METC bench-scale coal-water slurry combustor: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Celik, I.; Chattree, M.

1988-09-01

The isothermal turbulent, swirling flow inside the METC pressurized bench-scale combustor has been simulated using ISOPCGC-2. The effects of the swirl numbers, the momentum ratio of the primary to secondary streams, the annular wall thickness, and the quarl angle on the flow and mixing patterns have been investigated. The results that with the present configuration of the combustor, an annular recirculation zone is present up to secondary swirl number of four. A central (on axis) recirculation zone can be obtained by increasing the momentum of the secondary stream by decreasing the annular area at the reactor inlet. The mixing ofmore » the primary (fuel carrier) air with the secondary air improves only slightly due to swirl unless a central recirculation zone is present. Good mixing is achieved in the quarl region when a central recirculation zone is present. A preliminary investigation of the influence of placing flow regulators inside the the combustor shows that they influence the flow field significantly and that there is a potential of obtaining optimum flow conditions using these flow regulators. 58 refs., 47 figs., 12 tabs.« less

Dynamical behavior of lean swirling premixed flame generated by change in gravitational orientation

NASA Astrophysics Data System (ADS)

Gotoda, Hiroshi; Miyano, Takaya; Shepherd, Ian

2010-11-01

The dynamic behavior of flame front instability in lean swirling premixed flame generated by the effect of gravitational orientation has been experimentally investigated in this work. When the gravitational direction is changed relative to the flame front, i.e., in inverted gravity, an unstably fluctuating flame (unstable flame) is formed in a limited domain of equivalence ratio and swirl number (Gotoda. H et al., Physical Review E, vol. 81, 026211, 2010). The time history of flame front fluctuations show that in the buoyancy-dominated region, chaotic irregular fluctuation with low frequencies is superimposed on the dominant periodic oscillation of the unstable flame. This periodic oscillation is produced by unstable large-scale vortex motion in combustion products generated by a change in the buoyancy/swirl interaction due to the inversion of gravitational orientation. As a result, the dynamic behavior of the unstable flame becomes low-dimensional deterministic chaos. Its dynamics maintains low-dimensional deterministic chaos even in the momentum-dominated region, in which vortex breakdown in the combustion products clearly occurs. These results were clearly demonstrated by the use of nonlinear time series analysis based on chaos theory, which has not been widely applied to the investigation of combustion phenomena.

Experimental investigation of in-cylinder air flow to optimize number of helical guide vanes to enhance DI diesel engine performance using mamey sapote biodiesel

NASA Astrophysics Data System (ADS)

Kumar, A. Raj; Janardhana Raju, G.; Hemachandra Reddy, K.

2018-03-01

The current research work investigates the influence of helical guide vanes in to the intake runner of a D.I diesel engine operating by the high viscous Mamey Sapote biodiesel to enhance in-cylinder suction air flow features. Helical guide vanes of different number of vanes are produced from 3D printing and placed in the intake manifold to examine the air flow characteristics. Four different helical guide vane devices namely 3, 4, 5 and 6 vanes of the same dimensions are tested in a D.I diesel engine operating with Mamey Sapote biodiesel blend. As per the experimental results of engine performance and emission characteristics, it is found that 5 vanes helical guide vane swirl device exhibited in addition number of increased improvements such as the brake power and bake thermal efficiency by 2.4% and 8.63% respectively and the HC, NOx, Carbon monoxide and, Smoke densities are reduced by 15.62%, 4.23%, 14.27% and 9.6% at peak load operating conditions as collate with normal engine at the same load. Hence this investigation concluded that Helical Guide Vane Devices successfully enhanced the in-cylinder air flow to improve better addition of Mamey Sapote biodiesel with air leading in better performance of the engine than without vanes.

Coaxial airblast atomizers

NASA Technical Reports Server (NTRS)

Hardalupas, Y.; Whitelaw, J. H.

1993-01-01

An experimental investigation was performed to quantify the characteristics of the sprays of coaxial injectors with particular emphasis on those aspects relevant to the performance of rocket engines. Measurements for coaxial air blast atomizers were obtained using air to represent the gaseous stream and water to represent the liquid stream. A wide range of flow conditions were examined for sprays with and without swirl for gaseous streams. The parameters varied include Weber number, gas flow rate, liquid flow rate, swirl, and nozzle geometry. Measurements were made with a phase Doppler velocimeter. Major conclusions of the study focused upon droplet size as a function of Weber number, effect of gas flow rate on atomization and spray spread, effect of nozzle geometry on atomization and spread, effect of swirl on atomization, spread, jet recirculation and breakup, and secondary atomization.

On the prediction of swirling flowfields found in axisymmetric combustor geometries

NASA Technical Reports Server (NTRS)

Rhode, D. L.; Lilley, D. G.; Mclaughlin, D. K.

1981-01-01

The paper reports research restricted to steady turbulence flow in axisymmetric geometries under low speed and nonreacting conditions. Numerical computations are performed for a basic two-dimensional axisymmetrical flow field similar to that found in a conventional gas turbine combustor. Calculations include a stairstep boundary representation of the expansion flow, a conventional k-epsilon turbulence model and realistic accomodation of swirl effects. A preliminary evaluation of the accuracy of computed flowfields is accomplished by comparisons with flow visualizations using neutrally-buoyant helium-filled soap bubbles as tracer particles. Comparisons of calculated results show good agreement, and it is found that a problem in swirling flows is the accuracy with which the sizes and shapes of the recirculation zones may be predicted, which may be attributed to the quality of the turbulence model.

Pollution emissions from single swirl-can combustor modules at parametric test conditions

NASA Technical Reports Server (NTRS)

Mularz, E. J.; Wear, J. D.; Verbulecz, P. W.

1975-01-01

Exhaust pollutant emissions were measured from single swirl-can combustor modules operating over a pressure range of 69 to 276 N/sq cm (100 to 400 psia), over a fuel-air ratio range of 0.01 to 0.04, at an inlet air temperature of 733 K (860 F), and at a constant reference velocity of 23.2 m/sec). Many swirl-can module designs were evaluated; the 11 most promising designs exhibited oxides of nitrogen emission levels lower than that from conventional gas-turbine combustors. Although these single module test results are not necessarily indicative of the performance characteristics of a large array of modules, the results are very promixing and offer a number of module designs that should be tested in a full combustor.

Turbulence intensity and spatial integral scale during compression and expansion strokes in a four-cycle reciprocating engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikegami, M.; Shioji, M.; Nishimoto, K.

1987-01-01

A laser homodyne technique is applied to measure turbulence intensities and spatial scales during compression and expansion strokes in a non-fired engine. By using this technique, relative fluid motion in a turbulent flow is detected directly without cyclic variation biases caused by fluctuation in the main flow. Experiments are performed at different engine speeds, compression ratios, and induction swirl ratios. In no-swirl cases the turbulence field near the compression end is almost uniform, whereas in swirled cases both the turbulence intensity and the scale near the cylinder axis are higher than those in the periphery. In addition, based on themore » measured results, the k-epsilon two-equation turbulence model under the influence of compression is discussed.« less

Variable camshaft timing system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butterfield, R.P.; Smith, F.R.

1989-09-05

This patent describes an improvement in a variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of the intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshaft, only one of the camshafts being directly driven by an engine crankshaft, and a timing chain engaging both sprockets. The improvement comprising a single bracket carrying at least one idler sprocket engaging the timing chain, the bracket being mounted for movement to alter the timing relationship between the intake and exhaust sprockets.

Propagation and scattering of acoustic-vorticity waves in annular swirling flows

NASA Astrophysics Data System (ADS)

Golubev, Vladimir Viktorovich

1997-08-01

The dissertation presents a fundamental extension of unsteady aerodynamic theory developed to predict fluctuating forces on aircraft structural components. These excitations may result from a variety of upstream flow non-uniformities such as atmospheric turbulence, airframe tip vortices and wakes, engine inlet distortions and secondary flows. In the frame of reference of a downstream aircraft component, an upstream flow non- uniformity appears as a propagating vorticity wave (a gust). Classical treatment of gust interaction problems developed for uniform, potential upstream mean flows is based on the fact that it is possible to consider separately incident or scattered acoustic, entropic and vortical modes of unsteady flow motion. A purely vortical gust remains 'frozen' as it convects with the flow. The coupling between different unsteady components may occur only at the surface of a solid structure, or in the close vicinity of a lifting body. The classical approach, however, is not justified for an aircraft engine system where the internal turbomachinery flow is non-uniform and non-potential as it exhibits a strong swirling motion. In such a flow, acting centrifugal and Coriolis forces couple the various unsteady modes which thus can no longer be determined independently of each other. The new developed theory follows the decomposition of unsteady velocity field into vortical and potential components. In spite of the modal coupling, this decomposition elucidates the physical phenomena associated with unsteady swirling motion by indicating the degree of interaction between the various modes. It paves the way for generalizing the classical definition of a gust for vortical swirling flows. The concept of a generalized gust is developed based on the eigenmode pseudospectral analysis of the coupled equations of unsteady swirling motion. This analysis reveals two distinct regions of eigenvalues corresponding to pressure-dominated nearly-sonic and vorticity- dominated nearly-convected eigenmodes. A compact discrete spectrum of nearly-convected eigenvalues clusters with infinitely increasing density approaching an accumulation convected critical layer. The generalized gust is then identified with the nearly-convected eigenspectrum and formulated in terms of a non-amplifying nearly-convected wave and an instability wave growing in the critical layer. Based on the generalized gust model, a boundary-value problem of unsteady three-dimensional acoustic-vorticity waves propagating in a vortical swirling flow and impinging on a turbomachinery blading is formulated and solved numerically. A set of benchmark results reveals a significant effect of swirling flow motion on aerodynamic and acoustic response of the annular cascade.

Maximal Oxygen Intake and Maximal Work Performance of Active College Women.

ERIC Educational Resources Information Center

Higgs, Susanne L.

Maximal oxygen intake and associated physiological variables were measured during strenuous exercise on women subjects (N=20 physical education majors). Following assessment of maximal oxygen intake, all subjects underwent a performance test at the work level which had elicited their maximal oxygen intake. Mean maximal oxygen intake was 41.32…

Numerical study of fire whirlwind taking into account radiative heat transfer

NASA Astrophysics Data System (ADS)

Sakai, S.; Miyagi, N.

2010-06-01

The fire whirlwind is a strong swirling flow with flame and spark, which may occur in the case of, widespread fire in the urban region by an earthquake disaster or an air raid, and a large-scale fire such as a forest fire. Fire whirlwind moves and promotes spread of fire and may extend serious damage rapidly. In this study, performing the numerical analysis of fire whirlwind with respect to scale effect, it is examined whether a relationship exists between a real phenomenon and the phenomenon in the reduction model with taking into account radiative heat transfer. Three dimensional analyses are performed to investigate the thermal and flow fields by using the analytical software FLUENT6.3. It is analyzed that those swirling flow in original scale, 1/10 scale, 1/50 scale, 1/100 scale from the original brake out to vanish. As an analytical condition, parameter calculation is repeated to get the velocity of a parallel flow which is the easiest to occur the swirling flow for each reduction model, and then scale effect is discussed by comparing the velocity of the natural convection, the velocity of the parallel flow, the center pressure of the whirlwind and the continuance time of the swirling flow. The analysis model of C-character heat source model is performed as well as the analysis in L-character model, which is one of the representative example of the fire whirlwind occurred at Tokyo in the Great Kanto Earthquake (1923). The result of the numerical analysis shows that there is a scale effect to the speed of the parallel flow to generate the swirling flow.

An adolescent weight-loss program integrating family variables reduces energy intake.

PubMed

Kitzman-Ulrich, Heather; Hampson, Robert; Wilson, Dawn K; Presnell, Katherine; Brown, Alan; O'Boyle, Mary

2009-03-01

Family variables such as cohesion and nurturance have been associated with adolescent weight-related health behaviors. Integrating family variables that improve family functioning into traditional weight-loss programs can provide health-related benefits. The current study evaluated a family-based psychoeducational and behavioral skill-building weight-loss program for adolescent girls that integrated Family Systems and Social Cognitive Theories. Forty-two overweight (> or = 95th percentile) female adolescent participants and parents participated in a 16-week randomized controlled trial comparing three groups: multifamily therapy plus psychoeducation (n=15), psychoeducation-only (n=16), or wait list (control; n=11) group. Body mass index, energy intake, and family measures were assessed at baseline and posttreatment. Adolescents in the psychoeducation-only group demonstrated a greater decrease in energy intake compared to the multifamily therapy plus psychoeducation and control groups (P<0.01). Positive changes in family nurturance were associated with lower levels of adolescent energy intake (P<0.05). No significant effects were found for body mass index. Results provide preliminary support for a psychoeducational program that integrates family variables to reduce energy intake in overweight adolescent girls. Results indicate that nurturance can be an important family variable to target in future adolescent weight-loss and dietary programs.

Do dietary patterns determine levels of vitamin B6, folate, and vitamin B12 intake and corresponding biomarkers in European adolescents? The Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study.

PubMed

Iglesia, Iris; Huybrechts, Inge; Mouratidou, Theodora; Santabárbara, Javier; Fernández-Alvira, Juan M; Santaliestra-Pasías, Alba M; Manios, Yannis; De la O Puerta, Alejandro; Kafatos, Anthony; Gottrand, Frédéric; Marcos, Ascensión; Sette, Stefania; Plada, Maria; Stehle, Peter; Molnár, Dénes; Widhalm, Kurt; Kersting, Mathilde; De Henauw, Stefaan; Moreno, Luis A; González-Gross, Marcela

2018-06-01

To determine dietary patterns (DPs) and explain the highest variance of vitamin B 6 , folate, and B 12 intake and related concentrations among European adolescents. A total of 2173 adolescents who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence study met the eligibility criteria for the vitamin B intake analysis (46% boys) and 586 adolescents for the biomarkers analysis (47% boys). Two non-consecutive, 24-h, dietary recalls were used to assess the mean intakes. Concentrations were measured by chromatography and immunoassay testing. A reduced rank regression was applied to elucidate the combined effect of food intake of vitamin B and related concentrations. The identified DPs (one per vitamin B intake and biomarker and by sex) explained a variability between 34.2% and 23.7% of the vitamin B intake and between 17.2% and 7% of the biomarkers. In the reduced rank regression models, fish, eggs, cheese, whole milk and buttermilk intakes were loaded positively for vitamin B intake in both sexes; however, soft drinks and chocolate were loaded negatively. For the biomarkers, a higher variability was observed in the patterns in terms of food loads such as alcoholic drinks, sugars, and soft drinks. Some food items were loaded differently between intakes and biomarkers such as fish products, which was loaded positively for intakes but negatively for plasma folate in girls. The identified DPs explained up to 34.2% and 17.2% of the variability of the vitamin B intake and plasma concentrations, respectively, in European adolescents. Further studies are needed to elucidate the factors that determine such patterns. Copyright © 2017 Elsevier Inc. All rights reserved.

CFD analysis of temperature imbalance in superheater/reheater region of tangentially coal-fired boiler

NASA Astrophysics Data System (ADS)

Zainudin, A. F.; Hasini, H.; Fadhil, S. S. A.

2017-10-01

This paper presents a CFD analysis of the flow, velocity and temperature distribution in a 700 MW tangentially coal-fired boiler operating in Malaysia. The main objective of the analysis is to gain insights on the occurrences in the boiler so as to understand the inherent steam temperature imbalance problem. The results show that the root cause of the problem comes from the residual swirl in the horizontal pass. The deflection of the residual swirl due to the sudden reduction and expansion of the flow cross-sectional area causes velocity deviation between the left and right side of the boiler. This consequently results in flue gas temperature imbalance which has often caused tube leaks in the superheater/reheater region. Therefore, eliminating the residual swirl or restraining it from being diverted might help to alleviate the problem.

An experimental investigation of flow around a vehicle passing through a tornado

NASA Astrophysics Data System (ADS)

Suzuki, Masahiro; Obara, Kouhei; Okura, Nobuyuki

2016-03-01

Flow around a vehicle running through a tornado was investigated experimentally. A tornado simulator was developed to generate a tornado-like swirl flow. PIV study confirmed that the simulator generates two-celled vortices which are observed in the natural tornadoes. A moving test rig was developed to run a 1/40 scaled train-shaped model vehicle under the tornado simulator. The car contained pressure sensors, a data logger with an AD converter to measure unsteady surface pressures during its run through the swirling flow. Aerodynamic forces acting on the vehicle were estimated from the pressure data. The results show that the aerodynamic forces change its magnitude and direction depending on the position of the car in the swirling flow. The asymmetry of the forces about the vortex centre suggests the vehicle itself may deform the flow field.

Performance and Stability Characteristics of a Uni-Element Swirl Injector for Oxygen-Rich Stage Combustion Cycles

NASA Technical Reports Server (NTRS)

Pal, S.; Kalitan, D.; Woodward, R. D.; Santoro, R. J.

2004-01-01

A uni-element liquid propellant combustion performance and instability study for liquid RP-1 and hot oxygen-rich pre-burner products was conducted, at a chamber pressure of about 1000 psi. using flush and recessed swirl injectors. High-frequency pressure transducer measurements were analyzed to yield the characteristic frequencies which were compared to expected frequencies of the chamber. Modes, which were discovered to be present within the main chamber included, the first longitudinal, detected at approximately 1950 Hz, and the second longitudinal mode at approximately 3800 Hz. An additional first longitudinal quarter wave mode was measured at a frequency of approximately 23000 Hz for the recessed swirl injector configuration. The characteristic instabilities resulting from these experiments were relatively weak averaging 0.2% to 0.3% of the chamber pressure.

Stress, sleep, depression and dietary intakes among low-income overweight and obese pregnant women.

PubMed

Chang, Mei-Wei; Brown, Roger; Nitzke, Susan; Smith, Barbara; Eghtedary, Kobra

2015-05-01

This study investigated the mediating roles of sleep and depression on the relationships between stress, fat intake, and fruit and vegetable intake among low-income overweight and obese pregnant women by trimesters. Participants (N = 213) completed a self-administered survey including stress (exogenous variable), depression, sleep (mediators), fat intake, and fruit and vegetable intake (endogenous variables). Path analysis was performed to compare mediation effects among pregnant women in each trimester. Consistently across three trimesters, stress was related to depression but not sleep duration, night time sleep disturbance, sleep quality, sleep latency or fat intake. Sleep duration was not associated with depression. Depending on trimester, night time sleep disturbance, sleep quality, and sleep latency were related to depression; night time sleep disturbance and depression affected fat intake; stress influenced fruit and vegetable intake. Sleep duration, sleep disturbance, sleep quality, sleep latency and depression did not mediate the relationships between stress, fat intake, and fruit and vegetable intake in the second and third trimesters. However, depression mediated the relationship between stress and fat intake in the first trimester. Stress management interventions may help low-income overweight and obese pregnant women decrease depressive symptoms and therefore contribute to overall nutritional health.

X-ray Radiography Measurements of Shear Coaxial Rocket Injectors

DTIC Science & Technology

2013-05-07

injector EPL profiles have elliptical shape expected from a solid liquid jet  EPL decreases as liquid core is atomized and droplets are...study diesel, swirl, gas-centered swirl-coaxial, impingers, and aerated liquid jet injectors  Use a monochromatic beam of x-rays at a synchrotron...Shear coaxial jets can be found in a number of combustion devices – Turbofan engine exhaust, air blast furnaces, and liquid rocket engines

An experimental investigation of two large annular diffusers with swirling and distorted inflow

NASA Technical Reports Server (NTRS)

Eckert, W. T.; Johnston, J. P.; Simons, T. D.; Mort, K. W.; Page, V. R.

1980-01-01

Two annular diffusers downstream of a nacelle-mounted fan were tested for aerodynamic performance, measured in terms of two static pressure recovery parameters (one near the diffuser exit plane and one about three diameters downstream in the settling duct) in the presence of several inflow conditions. The two diffusers each had an inlet diameter of 1.84 m, an area ratio of 2.3, and an equivalent cone angle of 11.5, but were distinguished by centerbodies of different lengths. The dependence of diffuser performance on various combinations of swirling, radially distorted, and/or azimuthally distorted inflow was examined. Swirling flow and distortions in the axial velocity profile in the annulus upstream of the diffuser inlet were caused by the intrinsic flow patterns downstream of a fan in a duct and by artificial intensification of the distortions. Azimuthal distortions or defects were generated by the addition of four artificial devices (screens and fences). Pressure recovery data indicated beneficial effects of both radial distortion (for a limited range of distortion levels) and inflow swirl. Small amounts of azimuthal distortion created by the artificial devices produced only small effects on diffuser performance. A large artificial distortion device was required to produce enough azimuthal flow distortion to significantly degrade the diffuser static pressure recovery.

Numerical investigation on the regression rate of hybrid rocket motor with star swirl fuel grain

NASA Astrophysics Data System (ADS)

Zhang, Shuai; Hu, Fan; Zhang, Weihua

2016-10-01

Although hybrid rocket motor is prospected to have distinct advantages over liquid and solid rocket motor, low regression rate and insufficient efficiency are two major disadvantages which have prevented it from being commercially viable. In recent years, complex fuel grain configurations are attractive in overcoming the disadvantages with the help of Rapid Prototyping technology. In this work, an attempt has been made to numerically investigate the flow field characteristics and local regression rate distribution inside the hybrid rocket motor with complex star swirl grain. A propellant combination with GOX and HTPB has been chosen. The numerical model is established based on the three dimensional Navier-Stokes equations with turbulence, combustion, and coupled gas/solid phase formulations. The calculated fuel regression rate is compared with the experimental data to validate the accuracy of numerical model. The results indicate that, comparing the star swirl grain with the tube grain under the conditions of the same port area and the same grain length, the burning surface area rises about 200%, the spatially averaged regression rate rises as high as about 60%, and the oxidizer can combust sufficiently due to the big vortex around the axis in the aft-mixing chamber. The combustion efficiency of star swirl grain is better and more stable than that of tube grain.

Certainties and Uncertainties in CFD Prediction of the End of the Vortex Behaviour in Centrifugal Separators

NASA Astrophysics Data System (ADS)

Pisarev, Gleb I.; Hoffmann, Alex C.

2011-09-01

This paper compares CFD simulations of the `end of the vortex' (EoV) behaviour in centrifugal separators with experiment. The EoV was studied in `swirl tubes', cylindrical cyclone separators with swirl vanes. We refer to the EoV as the phenomenon whereby the core of the vortex does not reach the bottom of the separator, but deviates from the swirl tube axis and attaches to the wall, where it rotates at some level above the bottom. The crucial parameters governing the EoV are geometrical, specifically the ratio of the separator length to its diameter (L/D), and operational, specifically the fluid flowrate. Swirl tubes with varying body lengths have been studied experimentally and numerically. CFD simulations were carried out using the commercial package Star-CD. The 3-D Navier-Stokes equations were solved using the finite volume method based on the SIMPLE pressure-correction algorithm and the LES turbulence model. The vortex behaviour was very similar between the experiments and the numerical simulations, this agreement being both qualitative and quantitative. However, there were some cases where the CFD predictions showed only qualitative agreement with experiments, with some of the parameter-values delimiting given types of flows being somewhat different between experiment and simulations.

Simulating the Reiner Gamma Lunar Swirl: Influence of the Upstream Plasma Conditions

NASA Astrophysics Data System (ADS)

Deca, J.; Gerard, M. J.; Divin, A. V.; Lue, C.; Ahmadi, T.; Lembege, B.; Horanyi, M.

2017-12-01

The Reiner Gamma swirl formation, co-located with one of our Moon's strongest crustal magnetic anomalies, is one of the most prominent lunar surface features. Due to Reiner Gamma's fairly moderate spatial scales, it presents an ideal test case to study the solar wind interaction with its magnetic topology from an ion-electron kinetic perspective. Using a fully kinetic particle-in-cell approach, coupled with a surface vector mapping magnetic field model based on Kaguya and Lunar Prospector observations, we are able to constrain both the reflected as well as the incident flux patterns to the lunar surface. Finding excellent agreement with the in-orbit flux measurements from the SARA:SWIM ion sensor onboard the Chandrayaan-1 spacecraft and the surface albedo images from the Lunar Reconnaissance Orbiter Wide Angle Camera we conclude that (from a pure plasma physics point of view) that solar wind standoff is a viable mechanism for the formation of lunar swirls. Here we show how the reflected and incident flux patterns change under influence of the upstream plasma and magnetic field conditions. The possible consequences of crustal magnetic anomalies for lunar swirl formation are essential for the interpretation of our Moon's geological history and evolution, space weathering, and to evaluate the needs and targets for future lunar exploration opportunities.

The role of drop velocity in statistical spray description

NASA Technical Reports Server (NTRS)

Groeneweg, J. F.; El-Wakil, M. M.; Myers, P. S.; Uyehara, O. A.

1978-01-01

The justification for describing a spray by treating drop velocity as a random variable on an equal statistical basis with drop size was studied experimentally. A double exposure technique using fluorescent drop photography was used to make size and velocity measurements at selected locations in a steady ethanol spray formed by a swirl atomizer. The size velocity data were categorized to construct bivariate spray density functions to describe the spray immediately after formation and during downstream propagation. Bimodal density functions were formed by environmental interaction during downstream propagation. Large differences were also found between spatial mass density and mass flux size distribution at the same location.

The effect of socio-demographic variables and dairy use on the intake of essential macro- and micronutrients in 0.5-12-year-old Indonesian children.

PubMed

Widodo, Yekti; Sandjaja, Sandjaja; Sumedi, Edith; Khouw, Ilse; Deurenberg, Paul

2016-01-01

To study the associations between nutrient intake, dairy intake and socioeconomic variables. Food consumption data using 24 h recall were collected in 3600 children, aged 0.5 to 12 years old in addition to frequency of dairy use and anthropometric and sociodemographic variables. Overall height for age Z-score (HAZ) and body mass index for age Z-score (BAZ) values (mean±SE) were -1.40±0.03 and -0.48±0.03 respectively, associated with a high prevalence of stunting and thinness in the population. The overall percentage of children not using any dairy products was 71%, and this percentage increased steadily with age. The overall energy intake from dairy was 99±3 kcal/capita/day and the overall energy intake from dairy in dairy users was 291±7 kcal/day. Dairy use did not differ between boys and girls, but was higher in urban areas, higher if the education of the mother was higher and higher if the mother had a permanent job and if the wealth status of the family was in the upper levels. Nutrient intake after the age of 3 years was inadequate for energy and all nutrients except for protein. The achievement of Recommended Dietary Allowances (RDA) for all nutrients was higher in dairy users compared to non-dairy users, also after correcting for the confounding effect of the higher energy intake (from dairy) and socio-demographic variables. The contribution increased with increasing frequency of dairy use. Adequate dairy intake can substantially add to the achievement of RDA in Indonesian children.

A Comparison of Shadowgraphy and X-ray Computed Tomography in Liquid Spray Analysis

DTIC Science & Technology

2014-11-14

atomizers and downstream of the nozzle exit gives insight into optimizing atomizers, particularly for combustion applications. The performance of gas ...regions near the spray nozzle [9, 10]. Because light refraction by liquid sheets is significant, these areas all cast a full shadow on the camera...hollow-cone pressure swirl design. Within this nozzle design, liquid swirls around an air-cored vortex. Upon exiting, the fluid expands due to its

Identification of Coherent Structure Dynamics in Wall-Bounded Sprays using Proper Orthogonal Decomposition

DTIC Science & Technology

2010-08-31

Wall interaction of sprays emanating from Gas Centered Swirl Coaxial (GCSC) injectors were experimentally studied as a part of this ten-week project. A...American Society of Engineering Education (ASEE) Dated August 31st 2010 Abstract Wall interaction of sprays emanating from Gas Centered...Edwards Air Force Base (AFRL/EAFB) have documented atomization characteristics of a Gas -Centered Swirl Coaxial (GCSC) injector [1-2], in which the

Design of a Generator for Near-Tangential Transonic Swirling Outflow.

DTIC Science & Technology

1984-12-01

of Turbine Blading , North American Aviation Inc, 1958. 8. Moses, H. L., Turbomachinery. Supplementary Notes, Naval Postgraduate School, 1983. 9...Streeter, V. L., and Wylie, B. E., Fluid Mqechanics, McGraw Hill, 1979 10. Vincent, E. T.,* The Theroy and Design of Gas Turbines and Jet Engines , McGraw...Radial Outflow Vanes ) Trarsonic Swirl Generation, Wedge-Arc Blading , 20. ABSTRACT (Continue on reverse side If necesary and Identify by block number

Investigations of flowfields found in typical combustor geometries

NASA Technical Reports Server (NTRS)

Lilley, D. G.

1982-01-01

Experimental and theoretical research undertaken on 2-D axisymmetric geometries under low speed, nonreacting, turbulent, swirling flow conditions is reported. The flow enters the test section and proceeds into a larger chamber (the expansion ratio D/d = 2) via a sudden or gradual expansion (sidewall angle alpha = 90 and 45 degrees). Inlet swirl vanes are adjustable to a variety of vane angles with values of phi = 0, 38, 45, 60 and 70 degrees being emphasized.

Swirls and Shadows

NASA Image and Video Library

2015-05-04

Saturn's surface is painted with swirls and shadows. Each swirl here is a weather system, reminding us of how dynamic Saturn's atmosphere is. Images taken in the near-infrared (like this one) permit us to peer through Saturn's methane haze layer to the clouds below. Scientists track the clouds and weather systems in the hopes of better understanding Saturn's complex atmosphere - and thus Earth's as well. This view looks toward the sunlit side of the rings from about 17 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on Feb. 8, 2015 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 794,000 miles (1.3 million kilometers) from Saturn. Image scale is 47 miles (76 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/pia18311

Energy Efficient Engine Exhaust Mixer Model Technology

NASA Technical Reports Server (NTRS)

Kozlowski, H.; Larkin, M.

1981-01-01

An exhaust mixer test program was conducted to define the technology required for the Energy Efficient Engine Program. The model configurations of 1/10 scale were tested in two phases. A parametric study of mixer design options, the impact of residual low pressure turbine swirl, and integration of the mixer with the structural pylon of the nacelle were investigated. The improvement of the mixer itself was also studied. Nozzle performance characteristics were obtained along with exit profiles and oil smear photographs. The sensitivity of nozzle performance to tailpipe length, lobe number, mixer penetration, and mixer modifications like scalloping and cutbacks were established. Residual turbine swirl was found detrimental to exhaust system performance and the low pressure turbine system for Energy Efficient Engine was designed so that no swirl would enter the mixer. The impact of mixer/plug gap was also established, along with importance of scalloping, cutbacks, hoods, and plug angles on high penetration mixers.

Predictions and measurements of isothermal flowfields in axisymmetric combustor geometries. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Rhodes, D. L.; Lilley, D. G.

1985-01-01

Numerical predictions, flow visualization experiments and time-mean velocity measurements were obtained for six basic nonreacting flowfields (with inlet swirl vane angles of 0 (swirler removed), 45 and 70 degrees and sidewall expansion angles of 90 and 45 degrees) in an idealized axisymmetric combustor geometry. A flowfield prediction computer program was developed which solves appropriate finite difference equations including a conventional two equation k-epsilon eddy viscosity turbulence model. The wall functions employed were derived from previous swirling flow measurements, and the stairstep approximation was employed to represent the sloping wall at the inlet to the test chamber. Recirculation region boundaries have been sketched from the entire flow visualization photograph collection. Tufts, smoke, and neutrally buoyant helium filled soap bubbles were employed as flow tracers. A five hole pitot probe was utilized to measure the axial, radial, and swirl time mean velocity components.

The investigation of soot and temperature distributions in a visualized direct injection diesel engine using laser diagnostics

NASA Astrophysics Data System (ADS)

Han, Yong-taek; Kim, Ki-bum; Lee, Ki-hyung

2008-11-01

Based upon the method of temperature calibration using the diffusion flame, the temperature and soot concentrations of the turbulent flame in a visualized diesel engine were qualitatively measured. Two different cylinder heads were used to investigate the effect of swirl ratio within the combustion chamber. From this experiment, we find that the highest flame temperature of the non-swirl head engine is approximately 2400 K and that of the swirl head engine is 2100 K. In addition, as the pressure of fuel injection increases, the in-cylinder temperature increases due to the improved combustion of a diesel engine. This experiment represented the soot quantity in the KL factor and revealed that the KL factor was high when the fuel collided with the cylinder wall. Moreover, the KL factor was also high in the area of the chamber where the temperature dropped rapidly.

An experimental study on premixed CNG/H2/CO2 mixture flames

NASA Astrophysics Data System (ADS)

Yilmaz, Ilker; Yilmaz, Harun; Cam, Omer

2018-03-01

In this study, the effect of swirl number, gas composition and CO2 dilution on combustion and emission behaviour of CNG/H2/CO2 gas mixtures was experimentally investigated in a laboratory scale combustor. Irrespective of the gas composition, thermal power of the combustor was kept constant (5 kW). All experiments were conducted at or near stoichiometric and the local atmospheric conditions of the city of Kayseri, Turkey. During experiments, swirl number was varied and the combustion performance of this combustor was analysed by means of centreline temperature distributions. On the other hand, emission behaviour was examined with respect to emitted CO, CO2 and NOx levels. Dynamic flame behaviour was also evaluated by analysing instantaneous flame images. Results of this study revealed the great impact of swirl number and gas composition on combustion and emission behaviour of studied flames.

Honeybee economics: optimisation of foraging in a variable world.

PubMed

Stabentheiner, Anton; Kovac, Helmut

2016-06-20

In honeybees fast and efficient exploitation of nectar and pollen sources is achieved by persistent endothermy throughout the foraging cycle, which means extremely high energy costs. The need for food promotes maximisation of the intake rate, and the high costs call for energetic optimisation. Experiments on how honeybees resolve this conflict have to consider that foraging takes place in a variable environment concerning microclimate and food quality and availability. Here we report, in simultaneous measurements of energy costs, gains, and intake rate and efficiency, how honeybee foragers manage this challenge in their highly variable environment. If possible, during unlimited sucrose flow, they follow an 'investment-guided' ('time is honey') economic strategy promising increased returns. They maximise net intake rate by investing both own heat production and solar heat to increase body temperature to a level which guarantees a high suction velocity. They switch to an 'economizing' ('save the honey') optimisation of energetic efficiency if the intake rate is restricted by the food source when an increased body temperature would not guarantee a high intake rate. With this flexible and graded change between economic strategies honeybees can do both maximise colony intake rate and optimise foraging efficiency in reaction to environmental variation.

Design, fabrication and acoustic tests of a 36 inch (0.914 meter) statorless turbotip fan

NASA Technical Reports Server (NTRS)

Smith, E. G.; Stempert, D. L.; Uhl, W. R.

1975-01-01

The LF336/E is a 36 inch (0.914 meter) diameter fan designed to operate in a rotor-alone configuration. Design features required for modification of the existing LF336/A rotor-stator fan into the LF336/E statorless fan configuration are discussed. Tests of the statorless fan identified an aerodynamic performance deficiency due to inaccurate accounting of the fan exit swirl during the aerodynamic design. This performance deficiency, related to fan exit static pressure levels, produced about a 20 percent thrust loss. A study was then conducted for further evaluation of the fan exit flow fields typical of statorless fan systems. This study showed that through proper selection of fan design variables such as pressure ratio, radius ratio, and swirl distributions, performance of a statorless fan configuration could be improved with levels of thrust approaching the conventional rotor-stator fan system. Acoustic measurements were taken for the statorless fan system at both GE and NASA, and when compared to other lift fan systems, showed noise levels comparable to the quietest lift fan configuration which included rotor-stator spacing and acoustic treatment. The statorless fan system was also used to determine effects of rotor leading edge serrations on noise generations. A cascade test program identified the serration geometry based on minimum pressure losses, wake turbulence levels and noise generations.

Experimental Investigation on Design Enhancement of Axial Fan Using Fixed Guide Vane

NASA Astrophysics Data System (ADS)

Munisamy, K. M.; Govindasamy, R.; Thangaraju, S. K.

2015-09-01

Airflow passes through the rotating blade in an axial flow fan will experience a helical flow pattern. This swirling effect leads the system to experience swirl energy losses or pressure drop yet reducing the total efficiency of the fan system. A robust tool to encounter this air spin past the blade is by introducing guide vane to the system. Owing to its importance, a new approach in designing outlet guide vane design for a commercial usage 1250mm diameter axial fan with a 30° pitch angle impeller has been introduced in this paper. A single line metal of proper curvature guide vane design technique has been adopted for this study. By choosing fan total efficiency as a target variable to be improved, the total and static pressure on the design point were set to be constraints. Therefore, the guide vane design was done based on the improvement target on the static pressure in system. The research shows that, with the improvement in static pressure by 29.63% through guide vane installation, the total fan efficiency is increased by 5.12%, thus reduces the fan power by 5.32%. Good agreement were found, that when the fan total efficiency increases, the power consumption of the fan is reduced. Therefore, this new approach of guide vane design can be applied to improve axial fan performance.

Association between blood cholesterol and sodium intake in hypertensive women with excess weight.

PubMed

Padilha, Bruna Merten; Ferreira, Raphaela Costa; Bueno, Nassib Bezerra; Tassitano, Rafael Miranda; Holanda, Lidiana de Souza; Vasconcelos, Sandra Mary Lima; Cabral, Poliana Coelho

2018-04-01

Restricted sodium intake has been recommended for more than 1 century for the treatment of hypertension. However, restriction seems to increase blood cholesterol. In women with excess weight, blood cholesterol may increase even more because of insulin resistance and the high lipolytic activity of adipose tissue.The aim of this study was to assess the association between blood cholesterol and sodium intake in hypertensive women with and without excess weight.This was a cross-sectional study with hypertensive and nondiabetic women aged 20 to 59 years, recruited at the primary healthcare units of Maceio, Alagoas, Brazilian Northeast. Excess weight was defined as body mass index (BMI) ≥25.0 kg/m. Sodium intake was estimated by the 24-hour urinary excretion of sodium. Blood cholesterol was the primary outcome investigated by this study, and its relationship with sodium intake and other variables was assessed by Pearson correlation and multivariate linear regression using a significance level of 5%.This study included 165 hypertensive women. Of these, 135 (81.8%) were with excess weight. The mean sodium intake was 3.7 g (±1.9) and 3.4 g (±2.4) in hypertensive women with and without excess weight, respectively. The multiple normal linear regression models fitted to the "blood cholesterol" in the 2 groups reveal that for the group of hypertensive women without excess weight only 1 independent variable "age" is statistically significant to explain the variability of the blood cholesterol levels. However, for the group of hypertensive women with excess weight, 2 independent variables, age and sodium intake, can statistically explain variations of the blood cholesterol levels.Blood cholesterol is statistically inversely related to sodium intake for hypertensive women with excess weight, but it is not statistically related to sodium intake for hypertensive women without excess weight.

Genome-wide interactions with dairy intake for body mass index in adults of European descent

USDA-ARS?s Scientific Manuscript database

Scope: Body weight responds variably to the intake of dairy foods. Genetic variation may contribute to inter-individual variability in associations between body weight and dairy consumption. Methods and results: We conducted a genome-wide interaction study to discover genetic variants that account f...

Triaxial Swirl Injector Element for Liquid-Fueled Engines

NASA Technical Reports Server (NTRS)

Muss, Jeff

2010-01-01

A triaxial injector is a single bi-propellant injection element located at the center of the injector body. The injector element consists of three nested, hydraulic swirl injectors. A small portion of the total fuel is injected through the central hydraulic injector, all of the oxidizer is injected through the middle concentric hydraulic swirl injector, and the balance of the fuel is injected through an outer concentric injection system. The configuration has been shown to provide good flame stabilization and the desired fuel-rich wall boundary condition. The injector design is well suited for preburner applications. Preburner injectors operate at extreme oxygen-to-fuel mass ratios, either very rich or very lean. The goal of a preburner is to create a uniform drive gas for the turbomachinery, while carefully controlling the temperature so as not to stress or damage turbine blades. The triaxial injector concept permits the lean propellant to be sandwiched between two layers of the rich propellant, while the hydraulic atomization characteristics of the swirl injectors promote interpropellant mixing and, ultimately, good combustion efficiency. This innovation is suited to a wide range of liquid oxidizer and liquid fuels, including hydrogen, methane, and kerosene. Prototype testing with the triaxial swirl injector demonstrated excellent injector and combustion chamber thermal compatibility and good combustion performance, both at levels far superior to a pintle injector. Initial testing with the prototype injector demonstrated over 96-percent combustion efficiency. The design showed excellent high -frequency combustion stability characteristics with oxygen and kerosene propellants. Unlike the more conventional pintle injector, there is not a large bluff body that must be cooled. The absence of a protruding center body enhances the thermal durability of the triaxial swirl injector. The hydraulic atomization characteristics of the innovation allow the design to be rapidly scaled from small in-space applications [500-5,000 lbf (2.2 22.2 kN)] to large thrust engine applications [80,000 lbf (356 kN) and beyond]. The triaxial injector is also less sensitive to eccentricities, manufacturing tolerances, and gap width of many traditional coaxial and pintle injector designs. The triaxial-injector injection orifice configuration provides for high injection stiffness. The low parts count and relatively large injector design features are amenable to low-cost production.

The effect of variable calcium and very low calcium diets on human calcium metabolism. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Chu, J.

1971-01-01

The effects of a very low calcium diet, with variable high and low protein intake, on the dynamics of calcium metabolism and the mechanism of calciuretics, are examined. The experiment, using male subjects, was designed to study the role of intestinal calcium absorption on urinary calcium excretion, and the rate of production of endogeneously secreted calcium in the gastrointestinal tract. The study showed an average of 70% fractional absorption rate during very low calcium intake, and that a decrease in renal tubular reabsorption of calcium is responsible for calciuretic effects of high protein intake. The study also indicates that there is a tendency to develop osteoporosis after long periods of low calcium intake, especially with a concurrent high protein intake.

Numerical evaluation of gas core length in free surface vortices

NASA Astrophysics Data System (ADS)

Cristofano, L.; Nobili, M.; Caruso, G.

2014-11-01

The formation and evolution of free surface vortices represent an important topic in many hydraulic intakes, since strong whirlpools introduce swirl flow at the intake, and could cause entrainment of floating matters and gas. In particular, gas entrainment phenomena are an important safety issue for Sodium cooled Fast Reactors, because the introduction of gas bubbles within the core causes dangerous reactivity fluctuation. In this paper, a numerical evaluation of the gas core length in free surface vortices is presented, according to two different approaches. In the first one, a prediction method, developed by the Japanese researcher Sakai and his team, has been applied. This method is based on the Burgers vortex model, and it is able to estimate the gas core length of a free surface vortex starting from two parameters calculated with single-phase CFD simulations. The two parameters are the circulation and the downward velocity gradient. The other approach consists in performing a two-phase CFD simulation of a free surface vortex, in order to numerically reproduce the gas- liquid interface deformation. Mapped convergent mesh is used to reduce numerical error and a VOF (Volume Of Fluid) method was selected to track the gas-liquid interface. Two different turbulence models have been tested and analyzed. Experimental measurements of free surface vortices gas core length have been executed, using optical methods, and numerical results have been compared with experimental measurements. The computational domain and the boundary conditions of the CFD simulations were set consistently with the experimental test conditions.

Effect of Swirl on an Unstable Single-Element Gas-Gas Rocket Engine

DTIC Science & Technology

2014-06-01

at 300 K, and the combustor is filled with a mixture of water and carbon dioxide at 1500 K. The warmer temperature in the combustor enables the auto...a variety of configurations including gas turbines and rocket engines.4–13 The single-element engine chosen for this study is the continuously...combustion systems including gas turbines , rocket engines, and industrial furnaces. Swirl can have dramatic effects on the flowfield; these include jet growth

Flow process in combustors

NASA Technical Reports Server (NTRS)

Gouldin, F. C.

1982-01-01

Fluid mechanical effects on combustion processes in steady flow combustors, especially gas turbine combustors were investigated. Flow features of most interest were vorticity, especially swirl, and turbulence. Theoretical analyses, numerical calculations, and experiments were performed. The theoretical and numerical work focused on noncombusting flows, while the experimental work consisted of both reacting and nonreacting flow studies. An experimental data set, e.g., velocity, temperature and composition, was developed for a swirl flow combustor for use by combustion modelers for development and validation work.

A concept for jet noise suppression for an afterburning turbojet engine

NASA Technical Reports Server (NTRS)

Chambellan, R. E.; Turek, R. J.

1972-01-01

A conceptual design of an afterburner system for turbojet engines which may reduce the jet exhaust noise by approximately 10 decibels is presented in this report. The proposed system consists of an array of swirl-can combustors and jet dividing nozzle tubes. The nozzle tubes translate axially upstream of the swirl cans when not in use. Results of preliminary design calculations and photographs of a kinematic model as applied to a hypothetical turbojet engine are presented.

Numerical analysis of combustion characteristics of hybrid rocket motor with multi-section swirl injection

NASA Astrophysics Data System (ADS)

Li, Chengen; Cai, Guobiao; Tian, Hui

2016-06-01

This paper is aimed to analyse the combustion characteristics of hybrid rocket motor with multi-section swirl injection by simulating the combustion flow field. Numerical combustion flow field and combustion performance parameters are obtained through three-dimensional numerical simulations based on a steady numerical model proposed in this paper. The hybrid rocket motor adopts 98% hydrogen peroxide and polyethylene as the propellants. Multiple injection sections are set along the axis of the solid fuel grain, and the oxidizer enters the combustion chamber by means of tangential injection via the injector ports in the injection sections. Simulation results indicate that the combustion flow field structure of the hybrid rocket motor could be improved by multi-section swirl injection method. The transformation of the combustion flow field can greatly increase the fuel regression rate and the combustion efficiency. The average fuel regression rate of the motor with multi-section swirl injection is improved by 8.37 times compared with that of the motor with conventional head-end irrotational injection. The combustion efficiency is increased to 95.73%. Besides, the simulation results also indicate that (1) the additional injection sections can increase the fuel regression rate and the combustion efficiency; (2) the upstream offset of the injection sections reduces the combustion efficiency; and (3) the fuel regression rate and the combustion efficiency decrease with the reduction of the number of injector ports in each injection section.

Twisting/Swirling Motions during a Prominence Eruption as Seen from SDO/AIA

NASA Astrophysics Data System (ADS)

Pant, V.; Datta, A.; Banerjee, D.; Chandrashekhar, K.; Ray, S.

2018-06-01

A quiescent prominence was observed at the northwest limb of the Sun using different channels of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We report and analyze twisting/swirling motions during and after the prominence eruption. We segregate the observed rotational motions into small and large scales. Small-scale rotational motions manifest in the barbs of the prominence, while the large-scale rotation manifests as the roll motion during the prominence eruption. We noticed that both footpoints of the prominence rotate in the counterclockwise direction. We propose that a similar sense of rotation in both footpoints leads to a prominence eruption. The prominence erupted asymmetrically near the southern footpoint, which may be due to an uneven mass distribution and location of the cavity near the southern footpoint. Furthermore, we study the swirling motion of the plasma along different circular paths in the cavity of the prominence after the prominence eruption. The rotational velocities of the plasma moving along different circular paths are estimated to be ∼9–40 km s‑1. These swirling motions can be explained in terms of twisted magnetic field lines in the prominence cavity. Finally we observe the twist built up in the prominence, being carried away by the coronal mass ejection, as seen in the Large Angle Spectrometric Coronagraph on board the Solar and Heliospheric Observatory.

Influence of the burner swirl on the azimuthal instabilities in an annular combustor

NASA Astrophysics Data System (ADS)

Mazur, Marek; Nygård, Håkon; Worth, Nicholas; Dawson, James

2017-11-01

Improving our fundamental understanding of thermoacoustic instabilities will aid the development of new low emission gas turbine combustors. In the present investigation the effects of swirl on the self-excited azimuthal combustion instabilities in a multi-burner annular annular combustor are investigated experimentally. Each of the burners features a bluff body and a swirler to stabilize the flame. The combustor is operated with an ethylene-air premixture at powers up to 100 kW. The swirl number of the burners is varied in these tests. For each case, dynamic pressure measurements at different azimuthal positions, as well as overhead imaging of OH* of the entire combustor are conducted simultaneously and at a high sampling frequency. The measurements are then used to determine the azimuthal acoustic and heat release rate modes in the chamber and to determine whether these modes are standing, spinning or mixed. Furthermore, the phase shift between the heat release rate and pressure and the shape of these two signals are analysed at different azimuthal positions. Based on the Rayleigh criterion, these investigations allow to obtain an insight about the effects of the swirl on the instability margins of the combustor. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement n° 677931 TAIAC).

Self-reported dietary intake of omega-3 fatty acids and association with bone and lower extremity function.

PubMed

Rousseau, James H; Kleppinger, Alison; Kenny, Anne M

2009-10-01

To assess the relationship between self-reported omega-3 fatty acid (O3FA) intake and bone mineral density (BMD) and lower extremity function in older adults. Cross-sectional analysis of baseline information from three separate ongoing studies of older adults, pooled for this analysis. Academic health center. Two hundred forty-seven men (n=118) and women (n=129) residing in the community or an assisted living facility. Self-reported dietary intake (O3FA, omega-6 fatty acids (O6FA), protein, and total calorie); BMD of the hip or heel; and lower extremity function including leg strength, chair rise time, walking speed, Timed Up and Go, and frailty. The mean reported intake of O3FA was 1.27 g/day. Correlation coefficients (r) between O3FA and T-scores from total femur (n=167) were 0.210 and 0.147 for combined femur and heel T scores. Similar correlations were found for leg strength (r=0.205) and chair rise time (r=-0.178), but the significance was lost when corrected for protein intake. Subjects with lower reported O3FA intake (<1.27 g/day) had lower BMD than those with higher reported O3FA intake. In a multiple regression analysis with femoral neck BMD as the dependent variable and reported intake of O3FA, O6FA, protein, and vitamin D as independent variables, reported O3FA intake was the only significant variable, accounting for 6% of the variance in BMD. Older adults had low reported intakes of O3FA. There was an association between greater reported O3FA intake and higher BMD. There was no independent association between reported O3FA intake and lower extremity function. Results from this preliminary report are promising and suggest further investigation.

Breakfast intake among adults with type 2 diabetes: is bigger better?

PubMed Central

Jarvandi, Soghra; Schootman, Mario; Racette, Susan B.

2015-01-01

Objective To assess the association between breakfast energy and total daily energy intake among individuals with type 2 diabetes. Design Cross-sectional study. Daily energy intake was computed from a 24-h dietary recall. Multiple regression models were used to estimate the association between daily energy intake (dependent variable) and quartiles of energy intake at breakfast (independent variable) expressed as either absolute or relative (% of total daily energy intake) terms. Orthogonal polynomial contrasts were used to test for linear and quadratic trends. Models were controlled for sex, age, race/ethnicity, body mass index, physical activity and smoking. In addition, we used separate multiple regression models to test the effect of quartiles of absolute and relative breakfast energy on intake at lunch, dinner, and snacks. Setting The 1999–2004 National Health and Nutrition Examination Survey (NHANES). Subjects Participants aged ≥ 30 years with self-reported history of diabetes (N = 1,146). Results Daily energy intake increased as absolute breakfast energy intake increased (linear trend, P < 0.0001; quadratic trend, P = 0.02), but decreased as relative breakfast energy intake increased (linear trend, P < 0.0001). In addition, while higher quartiles of absolute breakfast intake had no associations with energy intake at subsequent meals, higher quartiles of relative breakfast intake were associated with lower energy intake during all subsequent meals and snacks (P < 0.05). Conclusions Consuming a breakfast that provided less energy or comprised a greater proportion of daily energy intake was associated with lower total daily energy intake in adults with type 2 diabetes. PMID:25529061

A Culture-Specific Nutrient Intake Assessment Instrument in Patients with Pulmonary Tuberculosis

PubMed Central

Frediani, Jennifer K.; Tukvadze, Nestani; Sanikidze, Ekaterina; Kipiani, Maia; Hebbar, Gautam; Easley, Kirk A.; Shenvi, Neeta; Ramakrishnan, Usha; Tangpricha, Vin; Blumberg, Henry M.; Ziegler, Thomas R.

2013-01-01

Background and Aim To develop and evaluate a culture-specific nutrient intake assessment tool for use in adults with pulmonary tuberculosis (TB) in Tbilisi, Georgia. Methods We developed an instrument to measure food intake over 3 consecutive days using a questionnaire format. The tool was then compared to 24 hour food recalls. Food intake data from 31 subjects with TB were analyzed using the Nutrient Database System for Research (NDS-R) dietary analysis program. Paired t-tests, Pearson correlations and intraclass correlation coefficients (ICC) were used to assess the agreement between the two methods of dietary intake for calculated nutrient intakes. Results The Pearson correlation coefficient for mean daily caloric intake between the 2 methods was 0.37 (P = 0.04) with a mean difference of 171 kcals/day (p = 0.34). The ICC was 0.38 (95% CI: 0.03 to 0.64) suggesting the within-patient variability may be larger than between-patient variability. Results for mean daily intake of total fat, total carbohydrate, total protein, retinol, vitamins D and E, thiamine, calcium, sodium, iron, selenium, copper, and zinc between the two assessment methods were also similar. Conclusions This novel nutrient intake assessment tool provided quantitative nutrient intake data from TB patients. These pilot data can inform larger studies in similar populations. PMID:23541173

Genome-wide interactions with dairy intake for body mass index in adults of European descent

USDA-ARS?s Scientific Manuscript database

Body weight responds variably to the intake of dairy foods. Genetic variation may contribute to inter-individual variability in associations between body weight and dairy consumption. We conducted a genome-wide interaction study to discover genetic variants that account for variation in BMI in the c...

Variability in range cow mineral use is associated with season and daily high temperature in Northern Great Plains

USDA-ARS?s Scientific Manuscript database

Accurate assessment of mineral nutrition in range cattle is complicated by seasonal changes in diet mineral concentrations, shifting requirements and a lack of knowledge of seasonal mineral intake variability. This study was designed to evaluate variation in herd mineral intake, and individual cow m...

Effect of energy equation in one control-volume bulk-flow model for the prediction of labyrinth seal dynamic coefficients

NASA Astrophysics Data System (ADS)

Cangioli, Filippo; Pennacchi, Paolo; Vannini, Giuseppe; Ciuchicchi, Lorenzo

2018-01-01

The influence of sealing components on the rotordynamic stability of turbomachinery has become a key topic because the oil and gas market is increasingly demanding high rotational speeds and high efficiency. This leads the turbomachinery manufacturers to design higher flexibility ratios and to reduce the clearance of the seals. Accurate prediction of the effective damping of seals is critical to avoid instability problems; in recent years, "negative-swirl" swirl brakes have been used to reverse the circumferential direction of the inlet flow, which changes the sign of the cross-coupled stiffness coefficients and generates stabilizing forces. Experimental tests for a teeth-on-stator labyrinth seal were performed by manufacturers with positive and negative pre-swirl values to investigate the pre-swirl effect on the cross-coupled stiffness coefficient. Those results are used as a benchmark in this paper. To analyse the rotor-fluid interaction in the seals, the bulk-flow numeric approach is more time efficient than computational fluid dynamics (CFD). Although the accuracy of the coefficients prediction in bulk-flow models is satisfactory for liquid phase application, the accuracy of the results strongly depends on the operating conditions in the case of the gas phase. In this paper, the authors propose an improvement in the state-of-the-art bulk-flow model by introducing the effect of the energy equation in the zeroth-order solution to better characterize real gas properties due to the enthalpy variation along the seal cavities. The consideration of the energy equation allows for a better estimation of the coefficients in the case of a negative pre-swirl ratio, therefore, it extend the prediction fidelity over a wide range of operating conditions. The numeric results are also compared to the state-of-the-art bulk-flow model, which highlights the improvement in the model.

A Study on the Nonmetallic Inclusion Motions in a Swirling Flow Submerged Entry Nozzle in a New Cylindrical Tundish Design

NASA Astrophysics Data System (ADS)

Ni, Peiyuan; Ersson, Mikael; Jonsson, Lage Tord Ingemar; Jönsson, Pär Göran

2018-04-01

Different sizes and shapes of nonmetallic inclusions in a swirling flow submerged entry nozzle (SEN) placed in a new tundish design were investigated by using a Lagrangian particle tracking scheme. The results show that inclusions in the current cylindrical tundish have difficulties remaining in the top tundish region, since a strong rotational steel flow exists in this region. This high rotational flow of 0.7 m/s provides the required momentum for the formation of a strong swirling flow inside the SEN. The results show that inclusions larger than 40 µm were found to deposit to a smaller extent on the SEN wall compared to smaller inclusions. The reason is that these large inclusions have Separation number values larger than 1. Thus, the swirling flow causes these large size inclusions to move toward the SEN center. For the nonspherical inclusions, large size inclusions were found to be deposited on the SEN wall to a larger extent, compared to spherical inclusions. More specifically, the difference of the deposited inclusion number is around 27 pct. Overall, it was found that the swirling flow contains three regions, namely, the isotropic core region, the anisotropic turbulence region and the near-wall region. Therefore, anisotropic turbulent fluctuations should be taken into account when the inclusion motion was tracked in this complex flow. In addition, many inclusions were found to deposit at the SEN inlet region. The plotted velocity distribution shows that the inlet flow is very chaotic. A high turbulent kinetic energy value of around 0.08 m2/s2 exists in this region, and a recirculating flow was also found here. These flow characteristics are harmful since they increase the inclusion transport toward the wall. Therefore, a new design of the SEN inlet should be developed in the future, with the aim to modify the inlet flow so that the inclusion deposition is reduced.

Effect of variable water intake as mediated by dietary potassium carbonate supplementation on rumen dynamics in lactating dairy cows

USDA-ARS?s Scientific Manuscript database

Water is a critical nutrient for dairy cows, with intake varying with environment, production, and diet. However, little work has evaluated the effects of water intake on rumen parameters. Using dietary potassium carbonate (Kcarb) as a K supplement to increase water intake, the objective of this stu...

Mushroom intake is associated with better nutrient intake and diet quality: 2001-2010 National Health and Nutrition Examination Survey

USDA-ARS?s Scientific Manuscript database

The association between mushroom consumption and nutrient intake or diet quality has not been reported. The purpose of this study was to determine the associations between these variables in a nationally representative sample of adults. Dietary intake was determined using a 24-hour recall on adult 1...

Influence of dietary intake during gestation on postpartum weight retention.

PubMed

Martins, Ana Paula Bortoletto; Benicio, Maria Helena D'Aquino

2011-10-01

To evaluate the influence of dietary intake during gestation on postpartum weight retention. A total of 82 healthy pregnant women who began prenatal care at public healthcare services in the Municipality of São Paulo (Southeastern Brazil) between April and June 2005 were followed up. Weight and height were measured in the first interview (up to 16 weeks of gestation) and the weight measure was repeated during a household visit 15 days after delivery. The 24-Hour Dietary Recall method was employed to evaluate dietary intake at the three trimesters of gestation. The mean ingestion of saturated fat, fibers, added sugar, soft drinks, processed foods, fruits and vegetables, as well as the dietary energy density were calculated. Weight retention was estimated by the difference between the measure of the postpartum weight and the first measured weight. The influence of dietary intake on postpartum weight retention was assessed by multiple linear regression analysis and the linear trend test was performed. The variables used to adjust the model were: body mass index at the beginning of gestation, height, per capita family income, smoking, age, and level of schooling. The mean body mass index at the beginning of gestation was 24 kg/m² and the mean weight retention was 1.9 kg. The increase in saturated fat intake (p=0.005) and processed foods ingestion (p=0.014) significantly increased postpartum weight retention, after adjustment by the control variables. The other dietary intake variables did not present a significant relationship to the outcome variable. The increased intake of unhealthy food, such as processed foods, and of saturated fat influences the increment of postpartum weight retention.

Coherent Lagrangian swirls among submesoscale motions.

PubMed

Beron-Vera, F J; Hadjighasem, A; Xia, Q; Olascoaga, M J; Haller, G

2018-03-05

The emergence of coherent Lagrangian swirls (CLSs) among submesoscale motions in the ocean is illustrated. This is done by applying recent nonlinear dynamics tools for Lagrangian coherence detection on a surface flow realization produced by a data-assimilative submesoscale-permitting ocean general circulation model simulation of the Gulf of Mexico. Both mesoscale and submesoscale CLSs are extracted. These extractions prove the relevance of coherent Lagrangian eddies detected in satellite-altimetry-based geostrophic flow data for the arguably more realistic ageostrophic multiscale flow.

Interpretation of Core Length in Shear Coaxial Rocket Injectors from X-ray Radiography Measurements (Briefing Charts)

DTIC Science & Technology

2014-06-01

Distribution A: Approved for public release; distribution unlimited. • Near-injector EPL profiles have elliptical shape expected from a solid liquid jet ...the shear between an outer lower-density high-velocity annulus and a higher-density low-velocity inner jet to atomize and mix a liquid and a gas...Used to study diesel, swirl, gas-centered swirl-coaxial, impingers, and aerated liquid jet injectors • Use a monochromatic beam of X-rays

Nutrition Knowledge, Attitudes, and Fruit and Vegetable Intake as Predictors of Head Start Teachers' Classroom Mealtime Behaviors.

PubMed

Halloran, Katherine Marie; Gorman, Kathleen; Fallon, Megan; Tovar, Alison

2018-04-01

To examine the association between nutrition knowledge, attitudes, and fruit/vegetable intake among Head Start teachers and their classroom mealtime behaviors (self-reported and observed). Cross-sectional design using observation and survey. Sixteen Head Start centers across Rhode Island between September, 2014 and May, 2015. Teachers were e-mailed about the study by directors and were recruited during on-site visits. A total of 85 participants enrolled through phone/e-mail (19%) or in person (81%). Independent variables were nutrition knowledge, attitudes, and fruit/vegetable intake. The dependent variable was classroom mealtime behaviors (self-reported and observed). Regression analyses conducted on teacher mealtime behavior were examined separately for observation and self-report, with knowledge, attitudes, and fruit and vegetable intake as independent variables entered into the models, controlling for covariates. Nutrition attitudes were positively associated with teacher self-reported classroom mealtime behavior total score. Neither teacher nutrition knowledge nor fruit/vegetable intake was associated with observed or self-reported classroom mealtime behavior total scores. There was limited support for associations among teacher knowledge, attitudes, and fruit/vegetable intake, and teacher classroom mealtime behavior. Findings showed that teacher mealtime behavior was significantly associated with teacher experience. Copyright © 2017 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

Food environment and fruit and vegetable intake in a urban population: a multilevel analysis.

PubMed

Pessoa, Milene Cristine; Mendes, Larissa Loures; Gomes, Crizian Saar; Martins, Paula Andréa; Velasquez-Melendez, Gustavo

2015-10-05

Environmental, social and individual factors influence eating patterns, which in turn affect the risk of many chronic diseases. This study aimed to estimate associations between environmental factors and the consumption of fruit and vegetables among adults in a Brazilian urban context. Data from the surveillance system for risk factors for chronic diseases (VIGITEL) of Brazilian Ministry of Health were used. A cross-sectional telephone survey (VIGITEL - 2008-2010) was carried out with 5826 adults in the urban area of Belo Horizonte. Individual variables were collected. The frequency of fruit and vegetables consumption was assessed from number of servings, weekly frequency and an intake score was calculated. Georeferenced variables were used to characterize the food environment. The density of healthy food outlets (stores specialized in selling fruit and vegetables), unhealthy food outlets (bars, snack bars and food trucks/trailers) and the neighborhood family income were investigated and associated with fruit and vegetables intake score. Weighted multilevel linear regression was used to evaluate the associations between the environment variables and the fruit and vegetables intake score. Higher fruit and vegetables intake scores were observed in neighborhoods with higher density of healthy food outlets and higher income. Lower scores were observed in neighborhood with higher density of unhealthy food outlets. These associations were adjusted by individual variables such as gender, age, physical activity, sugar sweetened beverages consumption, education level and smoking. The food environment might explain some of the socioeconomic disparities with respect to healthy food intake and health outcomes. Healthy food stores are less common in socially disadvantaged neighborhoods, and therefore, healthy foods such as fruits and vegetables are less available or are of a lower quality in lower income areas. Food environment characteristics and neighborhood socioeconomic level had significant associations with fruit and vegetable intake score. These are initial findings that require further investigation within the middle income world populations and the role of the environment with respect to both healthy and unhealthy food acquisition and intake.

Investigating sex differences in psychological predictors of snack intake among a large representative sample.

PubMed

Adriaanse, Marieke A; Evers, Catharine; Verhoeven, Aukje A C; de Ridder, Denise T D

2016-03-01

It is often assumed that there are substantial sex differences in eating behaviour (e.g. women are more likely to be dieters or emotional eaters than men). The present study investigates this assumption in a large representative community sample while incorporating a comprehensive set of psychological eating-related variables. A community sample was employed to: (i) determine sex differences in (un)healthy snack consumption and psychological eating-related variables (e.g. emotional eating, intention to eat healthily); (ii) examine whether sex predicts energy intake from (un)healthy snacks over and above psychological variables; and (iii) investigate the relationship between psychological variables and snack intake for men and women separately. Snack consumption was assessed with a 7d snack diary; the psychological eating-related variables with questionnaires. Participants were members of an Internet survey panel that is based on a true probability sample of households in the Netherlands. Men and women (n 1292; 45 % male), with a mean age of 51·23 (sd 16·78) years and a mean BMI of 25·62 (sd 4·75) kg/m2. Results revealed that women consumed more healthy and less unhealthy snacks than men and they scored higher than men on emotional and restrained eating. Women also more often reported appearance and health-related concerns about their eating behaviour, but men and women did not differ with regard to external eating or their intentions to eat more healthily. The relationships between psychological eating-related variables and snack intake were similar for men and women, indicating that snack intake is predicted by the same variables for men and women. It is concluded that some small sex differences in psychological eating-related variables exist, but based on the present data there is no need for interventions aimed at promoting healthy eating to target different predictors according to sex.

Estimating usual intakes mainly affects the micronutrient distribution among infants, toddlers and pre-schoolers from the 2012 Mexican National Health and Nutrition Survey.

PubMed

Piernas, Carmen; Miles, Donna R; Deming, Denise M; Reidy, Kathleen C; Popkin, Barry M

2016-04-01

To compare estimates from one day with usual intake estimates to evaluate how the adjustment for within-person variability affected nutrient intake and adequacy in Mexican children. In order to obtain usual nutrient intakes, the National Cancer Institute's method was used to correct the first 24 h dietary recall collected in the entire sample (n 2045) with a second 24 h recall collected in a sub-sample (n 178). We computed estimates of one-day and usual intakes of total energy, fat, Fe, Zn and Na. 2012 Mexican National Health and Nutrition Survey. A total of 2045 children were included: 0-5·9 months old (n 182), 6-11·9 months old (n 228), 12-23·9 months old (n 537) and 24-47·9 months old (n 1098). From these, 178 provided an additional dietary recall. Although we found small or no differences in energy intake (kJ/d and kcal/d) between one-day v. usual intake means, the prevalence of inadequate and excessive energy intake decreased somewhat when using measures of usual intake relative to one day. Mean fat intake (g/d) was not different between one-day and usual intake among children >6 months old, but the prevalence of inadequate and excessive fat intake was overestimated among toddlers and pre-schoolers when using one-day intake (P6 months. There was overall low variability in energy and fat intakes but higher for micronutrients. Because the usual intake distributions are narrower, the prevalence of inadequate/excessive intakes may be biased when estimating nutrient adequacy if one day of data is used.

Divertor target for magnetic containment device

DOEpatents

Luzzi, Jr., Theodore E.

1982-01-01

In a plasma containment device of a type having superconducting field coils for magnetically shaping the plasma into approximately the form of a torus, an improved divertor target for removing impurities from a "scrape off" region of the plasma comprises an array of water cooled swirl tubes onto which the scrape off flux is impinged. Impurities reflected from the divertor target are removed from the target region by a conventional vacuum getter system. The swirl tubes are oriented and spaced apart within the divertor region relative to the incident angle of the scrape off flux to cause only one side of each tube to be exposed to the flux to increase the burnout rating of the target. The divertor target plane is oriented relative to the plane of the path of the scrape off flux such that the maximum heat flux onto a swirl tube is less than the tube design flux. The containment device is used to contain the plasma of a tokamak fusion reactor and is applicable to other long pulse plasma containment systems.

Drop size distribution and air velocity measurements in air assist swirl atomizer sprays

NASA Technical Reports Server (NTRS)

Mao, C.-P.; Oechsle, V.; Chigier, N.

1987-01-01

Detailed measurements of mean drop size (SMD) and size distribution parameters have been made using a Fraunhofer diffraction particle sizing instrument in a series of sprays generated by an air assist swirl atomizer. Thirty-six different combinations of fuel and air mass flow rates were examined with liquid flow rates up to 14 lbm/hr and atomizing air flow rates up to 10 lbm/hr. Linear relationships were found between SMD and liquid to air mass flow rate ratios. SMD increased with distance downstream along the center line and also with radial distance from the axis. Increase in obscuration with distance downstream was due to an increase in number density of particles as the result of deceleration of drops and an increase in the exposed path length of the laser beam. Velocity components of the atomizing air flow field measured by a laser anemometer show swirling jet air flow fields with solid body rotation in the core and free vortex flow in the outer regions.

Characterization of a novel micro-pressure swirl reactor for removal of chemical oxygen demand and total nitrogen from domestic wastewater at low temperature.

PubMed

Ren, Qingkai; Yu, Yang; Zhu, Suiyi; Bian, Dejun; Huo, Mingxin; Zhou, Dandan; Huo, Hongliang

2017-06-01

A novel micro-pressure swirl reactor (MPSR) was designed and applied to treat domestic wastewater at low temperature by acclimating microbial biomass with steadily decreasing temperature from 15 to 3 °C. Chemical oxygen demand (COD) was constantly removed by 85% and maintained below 50 mg L -1 in the effluent during the process. When the air flow was controlled at 0.2 m 3  h -1 , a swirl circulation was formed in the reactor, which created a dissolved oxygen (DO) gradient with a low DO zone in the center and a high DO zone in the periphery for denitrification and nitrification. 81% of total nitrogen was removed by this reactor, in which ammonium was reduced by over 90%. However, denitrification was less effective because of the presence of low levels of oxygen. The progressively decreasing temperature favored acclimation of psychrophilic bacteria in the reactor, which replaced mesophilic bacteria in the process of treatment.

The effect of swirl recovery vanes on the cruise noise of an advanced propeller

NASA Technical Reports Server (NTRS)

Dittmar, James H.; Hall, David G.

1990-01-01

The SR-7A propeller was acoustically tested with and without downstream swirl recovery vanes to determine if any extra noise was caused by the interaction of the propeller wakes and vortices with these vanes. No additional noise was observed at the cruise condition over the angular range tested. The presence of the swirl recovery vanes did unload the propeller and some small peak noise reductions were observed from lower propeller loading noise. The propeller was also tested alone to investigate the behavior of the peak propeller noise with helical tip Mach number. As observed before on other propellers, the peak noise first rose with helical tip Mach number and then leveled off or decreased at higher helical tip Mach numbers. Detailed pressure-time histories indicate that a portion of the primary pressure pulse is progressively cancelled by a secondary pulse as the helical tip Mach number is increased. This cancellation appears to be responsible for the peak noise behavior at high helical tip Mach numbers.

Characteristics of Tornado-Like Vortices Simulated in a Large-Scale Ward-Type Simulator

NASA Astrophysics Data System (ADS)

Tang, Zhuo; Feng, Changda; Wu, Liang; Zuo, Delong; James, Darryl L.

2018-02-01

Tornado-like vortices are simulated in a large-scale Ward-type simulator to further advance the understanding of such flows, and to facilitate future studies of tornado wind loading on structures. Measurements of the velocity fields near the simulator floor and the resulting floor surface pressures are interpreted to reveal the mean and fluctuating characteristics of the flow as well as the characteristics of the static-pressure deficit. We focus on the manner in which the swirl ratio and the radial Reynolds number affect these characteristics. The transition of the tornado-like flow from a single-celled vortex to a dual-celled vortex with increasing swirl ratio and the impact of this transition on the flow field and the surface-pressure deficit are closely examined. The mean characteristics of the surface-pressure deficit caused by tornado-like vortices simulated at a number of swirl ratios compare well with the corresponding characteristics recorded during full-scale tornadoes.

Introduction of low-temperature swirl technology of burning as a way of increase in ecological of low power boilers

NASA Astrophysics Data System (ADS)

Trinchenko, A. A.; Paramonov, A. P.

2017-10-01

Work is devoted to the solution of problems of energy efficiency increase in low power boilers at combustion of solid fuel. The technological method of nitrogen oxides decomposition on a surface of carbon particles with education environmentally friendly carbonic acid and molecular nitrogen is considered during the work of a low-temperature swirl fire chamber. Based on the analysis of physical and chemical processes of a fuel chemically connected energy transition into thermal, using the diffusive and kinetic theory of burning modern approaches the technique, mathematical model and the settlement program for assessment of plant ecological indicators when using a new method are developed. Alternative calculations of furnace process are carried out, quantitative assessment of nitrogen oxides emissions level of the reconstructed boiler is executed. The results of modeling and experimental data have approved that the organization of swirl burning increases overall performance of a fire chamber and considerably reduces emissions of nitrogen oxides.

Optical monitoring system for a turbine engine

DOEpatents

Lemieux, Dennis H; Smed, Jan P; Williams, James P; Jonnalagadda, Vinay

2013-05-14

The monitoring system for a gas turbine engine including a viewing tube assembly having an inner end and an outer end. The inner end is located adjacent to a hot gas flow path within the gas turbine engine and the outer end is located adjacent to an outer casing of the gas turbine engine. An aperture wall is located at the inner end of the viewing tube assembly and an optical element is located within the viewing tube assembly adjacent to the inner end and is spaced from the aperture wall to define a cooling and purge chamber therebetween. An aperture is defined in the aperture wall for passage of light from the hot gas flow path to the optical element. Swirl passages are defined in the viewing tube assembly between the aperture wall and the optical element for passage of cooling air from a location outside the viewing tube assembly into the chamber, wherein swirl passages effect a swirling movement of air in a circumferential direction within the chamber.

Experimental investigation of the turbulent axisymmetric wake with rotation generated by a wind turbine

NASA Astrophysics Data System (ADS)

Dufresne, Nathaniel P.

An experimental investigation of the axial and azimuthal (swirl) velocity field in the wake of a single 3-bladed wind turbine with rotor diameter of 0.91m was conducted, up to 20 diameters downstream. The turbine was positioned in the free stream, near the entrance of the 6m x 2.7m cross section of the University of New Hampshire (UNH) Flow Physics Facility. Velocity measurements were conducted at different rotor loading conditions with blade tip-speed ratios from 2.0 to 2.8. A Pitot-static tube and constant temperature hot-wire anemometer with a multi-wire sensor were used to measure velocity fields. An equilibrium similarity theory for the turbulent axisymmetric wake with rotation was outlined, and first evidence for a new scaling function for the mean swirling velocity component, Wmax ∝ x-1 ∝ U3/2o a was found; where W represents swirl, x represents downstream distance, and Uo, represents the centerline velocity deficit in the wake.

Effects of Swirler Shape on Two-Phase Swirling Flow in a Steam Separator

NASA Astrophysics Data System (ADS)

Kataoka, Hironobu; Shinkai, Yusuke; Tomiyama, Akio

Experiments on two-phase swirling flow in a separator are carried out using several swirlers having different vane angles, different hub diameters and different number of vanes to seek a way for improving steam separators of uprated boiling water reactors. Ratios of the separated liquid flow rate to the total liquid flow rate, flow patterns, liquid film thicknesses and pressure drops are measured to examine the effects of swirler shape on air-water two-phase swirling annular flows in a one-fifth scale model of the separator. As a result, the following conclusions are obtained for the tested swirlers: (1) swirler shape scarcely affects the pressure drop in the barrel of the separator, (2) decreasing the vane angle is an effective way for reducing the pressure drop in the diffuser of the separator, and (3) the film thickness at the inlet of the pick-off-ring of the separator is not sensitive to swirler shape, which explains the reason why the separator performance does not depend on swirler shape.

Two opposed lateral jets injected into swirling crossflow

NASA Technical Reports Server (NTRS)

Lilley, D. G.; Mcmurry, C. B.; Ong, L. H.

1987-01-01

Experiments have been conducted to obtain the time-mean and turbulent quantities of opposed lateral jets in a low speed, nonreacting flowfield. A jet-to-crossflow velocity ratio of R = 4 was used throughout the experiments, with swirl vane angles of 0 (swirler removed), 45 and 70 degrees used with the crossflow. Flow visualization techniques used were neutrally-buoyant helium-filled soap bubbles and multispark photography in order to obtain the gross flowfield characteristics. Measurements of time-mean and turbulent quantities were obtained utilizing a six-orientation single hot-wire technique. For the nonswirling case, the jets were found not to penetrate past the test-section centerline, in contrast to the single lateral jet with the same jet-to-crossflow velocity ratio. In the swirling cases, the crossflow remains in a narrow region near the wall of the test section. The opposed jets are swept from their vertical courses into spiral trajectories close to the confining walls. Extensive results are presented in r-x plane plots.

Small-Scale Hybrid Rocket Test Stand & Characterization of Swirl Injectors

NASA Astrophysics Data System (ADS)

Summers, Matt H.

Derived from the necessity to increase testing capabilities of hybrid rocket motor (HRM) propulsion systems for Daedalus Astronautics at Arizona State University, a small-scale motor and test stand were designed and developed to characterize all components of the system. The motor is designed for simple integration and setup, such that both the forward-end enclosure and end cap can be easily removed for rapid integration of components during testing. Each of the components of the motor is removable allowing for a broad range of testing capabilities. While examining injectors and their potential it is thought ideal to obtain the highest regression rates and overall motor performance possible. The oxidizer and fuel are N2O and hydroxyl-terminated polybutadiene (HTPB), respectively, due to previous experience and simplicity. The injector designs, selected for the same reasons, are designed such that they vary only in the swirl angle. This system provides the platform for characterizing the effects of varying said swirl angle on HRM performance.

Numerical modeling of turbulent swirling flow in a multi-inlet vortex nanoprecipitation reactor using dynamic DDES

NASA Astrophysics Data System (ADS)

Hill, James C.; Liu, Zhenping; Fox, Rodney O.; Passalacqua, Alberto; Olsen, Michael G.

2015-11-01

The multi-inlet vortex reactor (MIVR) has been developed to provide a platform for rapid mixing in the application of flash nanoprecipitation (FNP) for manufacturing functional nanoparticles. Unfortunately, commonly used RANS methods are unable to accurately model this complex swirling flow. Large eddy simulations have also been problematic, as expensive fine grids to accurately model the flow are required. These dilemmas led to the strategy of applying a Delayed Detached Eddy Simulation (DDES) method to the vortex reactor. In the current work, the turbulent swirling flow inside a scaled-up MIVR has been investigated by using a dynamic DDES model. In the DDES model, the eddy viscosity has a form similar to the Smagorinsky sub-grid viscosity in LES and allows the implementation of a dynamic procedure to determine its coefficient. The complex recirculating back flow near the reactor center has been successfully captured by using this dynamic DDES model. Moreover, the simulation results are found to agree with experimental data for mean velocity and Reynolds stresses.

Coupling between premixed flame propagation and swirl flow during boundary layer flashback

NASA Astrophysics Data System (ADS)

Ebi, Dominik; Ranjan, Rakesh; Clemens, Noel T.

2018-07-01

Flashback of premixed methane-air flames in the turbulent boundary layer of swirling flows is investigated experimentally. The premix section of the atmospheric model swirl combustor features an axial swirler with an attached center-body. Our previous work with this same configuration investigated the flame propagation during flashback using particle image velocimetry (PIV) with liquid droplets as seed particles that precluded making measurements in the burnt gases. The present study investigates the transient velocity field in the unburnt and burnt gas region by means of solid-particle seeding and high-speed stereoscopic PIV. The global axial and circumferential lab-frame flame propagation speed is obtained simultaneously based on high-speed chemiluminescence movies. By combining the PIV data with the global flame propagation speed, the quasi-instantaneous swirling motion of the velocity field is constructed on annular shells, which provides a more intuitive view on the complex three-dimensional flow-flame interaction. Previous works showed that flashback is led by flame tongues. We find that the important flow-flame interaction occurs on the far side of these flame tongues relative to the approach flow, which we henceforth refer to as the leading side. The leading side is found to propagate as a classical premixed flame front relative to the strongly modified approach flow field. The blockage imposed by flame tongues is not limited to the immediate vicinity of the flame base, but occurs along the entire leading side.

Local Heat Flux Measurements with Single and Small Multi-element Coaxial Element-Injectors

NASA Technical Reports Server (NTRS)

Jones, Gregg; Protz, Christopher; Bullard, Brad; Hulka, James

2006-01-01

To support NASA's Vision for Space Exploration mission, the NASA Marshall Space Flight Center conducted a program in 2005 to improve the capability to predict local thermal compatibility and heat transfer in liquid propellant rocket engine combustion devices. The ultimate objective was to predict and hence reduce the local peak heat flux due to injector design, resulting in a significant improvement in overall engine reliability and durability. Such analyses are applicable to combustion devices in booster, upper stage, and in-space engines with regeneratively cooled chamber walls, as well as in small thrust chambers with few elements in the injector. In this program, single and three-element injectors were hot-fire tested with liquid oxygen and gaseous hydrogen propellants at The Pennsylvania State University Cryogenic Combustor Laboratory from May to August 2005. Local heat fluxes were measured in a 1-inch internal diameter heat sink combustion chamber using Medtherm coaxial thermocouples and Gardon heat flux gauges, Injector configurations were tested with both shear coaxial elements and swirl coaxial elements. Both a straight and a scarfed single element swirl injector were tested. This paper includes general descriptions of the experimental hardware, instrumentation, and results of the hot-fire testing for three coaxial shear and swirl elements. Detailed geometry and test results the for shear coax elements has already been published. Detailed test result for the remaining 6 swirl coax element for the will be published in a future JANNAF presentation to provide well-defined data sets for development and model validation.

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

NASA Technical Reports Server (NTRS)

Micklow, Gerald J.; Dogra, Anju S.; Nguyen, H. Lee

1990-01-01

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.

Review of Combustion Stability Characteristics of Swirl Coaxial Element Injectors

NASA Technical Reports Server (NTRS)

Hulka, J. R.; Casiano, M. J.

2013-01-01

Liquid propellant rocket engine injectors using coaxial elements where the center liquid is swirled have become more common in the United States over the past several decades, although primarily for technology or advanced development programs. Currently, only one flight engine operates with this element type in the United States (the RL10 engine), while the element type is very common in Russian (and ex-Soviet) liquid propellant rocket engines. In the United States, the understanding of combustion stability characteristics of swirl coaxial element injectors is still very limited, despite the influx of experimental and theoretical information from Russia. The empirical and theoretical understanding is much less advanced than for the other prevalent liquid propellant rocket injector element types, the shear coaxial and like-on-like paired doublet. This paper compiles, compares and explores the combustion stability characteristics of swirl coaxial element injectors tested in the United States, dating back to J-2 and RL-10 development, and extending to very recent programs at the NASA MSFC using liquid oxygen and liquid methane and kerosene propellants. Included in this study are several other relatively recent design and test programs, including the Space Transportation Main Engine (STME), COBRA, J-2X, and the Common Extensible Cryogenic Engine (CECE). A presentation of the basic data characteristics is included, followed by an evaluation by several analysis techniques, including those included in Rocket Combustor Interactive Design and Analysis Computer Program (ROCCID), and methodologies described by Hewitt and Bazarov.

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

NASA Astrophysics Data System (ADS)

Micklow, Gerald J.; Dogra, Anju S.; Nguyen, H. Lee

1990-07-01

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

NASA Astrophysics Data System (ADS)

Micklow, Gerald J.; Dogra, Anju S.; Nguyen, H. Lee

1990-06-01

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.

How do intake clinicians use patient characteristics to select treatment for patients with personality disorders?

PubMed

van Manen, Janine; Kamphuis, Jan Henk; Visbach, Geny; Ziegler, Uli; Gerritsen, Ad; Van Rossum, Bert; Rijnierse, Piet; Timman, Reinier; Verheul, Roel

2008-11-01

Treatment selection in clinical practice is a poorly understood, often largely implicit decision process, perhaps especially for patients with personality disorders. This study, therefore, investigated how intake clinicians use information about patient characteristics to select psychotherapeutic treatment for patients with personality disorder. A structured interview with a forced-choice format was administered to 27 experienced intake clinicians working in five specialist mental health care institutes in the Netherlands. Substantial consensus was evident among intake clinicians. The results revealed that none of the presented patient characteristics were deemed relevant for the selection of the suitable treatment setting. The appropriate duration and intensity are selected using severity or personal strength variables. The theoretical orientation is selected using personal strength variables.

Temperature field measurement research in high-speed diesel engine using laser induced fluorescence technology

NASA Astrophysics Data System (ADS)

Liu, Yongfeng; Zhang, You-tong; Gou, Chenhua; Tian, Hongsen

2008-12-01

Temperature laser- induced- fluorescence (LIF) 2-D imaging measurements using a new multi-spectral detection strategy are reported for high pressure flames in high-speed diesel engine. Schematic of the experimental set-up is outlined and the experimental data on the diesel engine is summarized. Experiment injection system is a third generation Bosch high-pressure common rail featuring a maximum pressure of 160 MPa. The injector is equipped with a six-hole nozzle, where each hole has a diameter of 0.124 mm. and slightly offset (by 1.0 mm) to the center of the cylinder axis to allow a better cooling of the narrow bridge between the exhaust valves. The measurement system includes a blower, which supplied the intake flow rate, and a prototype single-valve direct injection diesel engine head modified to lay down the swirled-type injector. 14-bit digital CCD cameras are employed to achieve a greater level of accuracy in comparison to the results of previous measurements. The temperature field spatial distributions in the cylinder for different crank angle degrees are carried out in a single direct-injection diesel engine.

2D temperature field measurement in a direct-injection engine using LIF technology

NASA Astrophysics Data System (ADS)

Liu, Yongfeng; Tian, Hongsen; Yang, Jianwei; Sun, Jianmin; Zhu, Aihua

2011-12-01

A new multi-spectral detection strategy for temperature laser- induced- fluorescence (LIF) 2-D imaging measurements is reported for high pressure flames in high-speed diesel engine. Schematic of the experimental set-up is outlined and the experimental data on the diesel engine is summarized. Experiment injection system is a third generation Bosch high-pressure common rail featuring a maximum pressure of 160MPa. The injector is equipped with a six-hole nozzle, where each hole has a diameter of 0.124 mm. and slightly offset to the center of the cylinder axis to allow a better cooling of the narrow bridge between the exhaust valves. The measurement system includes a blower, which supplied the intake flow rate, and a prototype single-valve direct injection diesel engine head modified to lay down the swirled-type injector. 14-bit digital CCD cameras are employed to achieve a greater level of accuracy in comparison to the results of previous measurements. The temperature field spatial distributions in the cylinder for different crank angle degrees are carried out in a single direct-injection diesel engine.

Correlates of energy intake and body mass index among homeless children in Minnesota.

PubMed

Richards, Rickelle; Smith, Chery; Eggett, Dennis L

2013-06-01

This study evaluated environmental, personal, and behavioral correlates of BMI-for-age percentiles, dietary intake (kilocalories, carbohydrates, protein, fat, and Food Guide Pyramid food groups), and physical activity variables among homeless children. A 74-item survey, using social cognitive theory as the theoretical framework, height, weight, and one 24-hour recall were collected from homeless children aged 9-13 (n=159) at two shelters in Minneapolis, MN. Principal component analysis was performed on the subsections of the survey. Independent t-tests, Fisher exact tests, and chi-squared statistics evaluated sociodemographic and BMI percentile variables. Nonparametric tests evaluated dietary data. Stepwise regression models evaluated correlates of BMI percentiles, physical activity, and dietary intake variables. Approximately 45% were overweight or obese (≥85(th) percentile). Dietary data represented intake on a given day, with children consuming a median 1.2 servings from the fruits and vegetables food group, 17.3 servings from the fats and sweets food group (one serving=grams in 1 Tbsp. fat/1 tsp. sugar), and the percent of calories from fat varying significantly between shelter 1 (S1) versus shelter 2 (S2) boys (37.1% vs. 31.7%, p<0.001). Factors identified from survey items and sociodemographic variables accounted for between 6% and 14% of the variance in energy intake and other dietary and physical activity variables (p range, 0.008 to <0.001). Parental role modeling of eating behaviors and getting enough food were associated with less favorable food choices among homeless children. Policy interventions and program initiatives in the homeless environment could promote healthier food choices among children.

Heart rate and blood pressure variabilities in salt-sensitive hypertension.

PubMed

Piccirillo, G; Bucca, C; Durante, M; Santagada, E; Munizzi, M R; Cacciafesta, M; Marigliano, V

1996-12-01

In salt-sensitive hypertension, a high sodium intake causes plasma catecholamines to rise and pulmonary baroreceptor plasticity to fall. In salt-sensitive and salt-resistant hypertensive subjects during low and high sodium intakes, we studied autonomic nervous system activity by power spectral analysis of heart rate and arterial pressure variabilities and baroreceptor sensitivity. In all subjects, high sodium intake significantly enhanced the low-frequency power of heart rate and arterial pressures at rest and after sympathetic stress. It also increased heart rate and arterial pressure variabilities. During high sodium intake, salt-sensitive hypertensive subjects had significantly higher low-frequency powers of systolic arterial pressure (7.5 mm Hg2, P < .05) and of heart rate at rest (59.2 +/- 2.4 normalized units [NU], P < .001) than salt-resistant subjects (6.6 +/- 0.3 mm Hg2, 55.0 +/- 3.2 NU) and normotensive control subjects (5.1 +/- 0.5 mm Hg2, 41.6 +/- 2.9 NU). In salt-sensitive subjects, low sodium intake significantly reduced low-frequency normalized units (P < .001) and the ratio of low- to high-power frequency (P < .001). High-sodium intake significantly increased baroreflex sensitivity in control subjects (from 10.0 +/- 0.7 to 17.5 +/- 0.7 ms/mm Hg, P < .001) and salt-resistant subjects (from 6.9 +/- 0.7 to 13.9 +/- 0.9, P < .05) but not in salt-sensitive subjects (7.4 +/- 0.3 to 7.9 +/- 0.4). In conclusion, a high sodium intake markedly enhances cardiac sympathetic activity in salt-sensitive and salt-resistant hypertension. In contrast, although reduced sodium intake lowers arterial pressure and sympathetic activity, it does so only in salt-sensitive subjects. Hence, in salt-resistant subjects, neither arterial pressure nor sympathetic activity depends on salt intake. During a high sodium intake in normotensive subjects and salt-resistant hypertensive subjects, increased sympathetic activity is probably compensated by enhanced baroreflex sensitivity.

Examining the relationship between vegetable intake of mothers and that of their children: a cross-sectional study of 10- to 12-year-old schoolchildren in Japan.

PubMed

Tada, Yuki; Tomata, Yasutake; Sunami, Ayaka; Yokoyama, Yuri; Hida, Azumi; Furusho, Tadasu; Kawano, Yukari

2015-12-01

The present study aimed to investigate the correlation between mothers' and children's vegetable intake and whether children are conscious about their vegetable intake. Cross-sectional study. Self-administered questionnaires for mothers and children, consisting of items regarding diet history, were distributed to children via homeroom teachers. We created dummy exposure variables for each quartile of mothers' vegetable intake. Multiple regression analysis was performed with children's vegetable intake as the outcome variable. Two public elementary schools in a residential district of Tokyo, Japan. Study participants were upper-grade children (aged 10-12 years) and their mothers (332 pairs of mothers and children). The mean vegetable intake in mothers and children was 310 (sd 145) g/d and 276 (sd 105) g/d, respectively. A positive linear relationship was found between mothers' and children's vegetable intake even after adjustment for considerable covariates (P<0·001). When stratified by children's consciousness, the positive linear relationship was more pronounced in children who were conscious of eating all their vegetables (P<0·001 for interaction with children's consciousness). Mothers' vegetable intake was significantly correlated with children's vegetable intake. However, this correlation was stronger in children who were conscious of eating all their vegetables. Our findings suggest that enhancing mother's vegetable intake and health consciousness of children are indispensable prerequisites for increasing vegetable intake among children.

Influence of energy drinks and alcohol on post-exercise heart rate recovery and heart rate variability.

PubMed

Wiklund, Urban; Karlsson, Marcus; Oström, Mats; Messner, Torbjörn

2009-01-01

Media have anecdotally reported that drinking energy drinks in combination with alcohol and exercise could cause sudden cardiac death. This study investigated changes in the electrocardiogram (ECG) and heart rate variability after intake of an energy drink, taken in combination with alcohol and exercise. Ten healthy volunteers (five men and five women aged 19-30) performed maximal bicycle ergometer exercise for 30 min after: (i) intake of 0.75 l of an energy drink mixed with alcohol; (ii) intake of energy drink; and, (iii) no intake of any drink. ECG was continuously recorded for analysis of heart rate variability and heart rate recovery. No subject developed any clinically significant arrhythmias. Post-exercise recovery in heart rate and heart rate variability was slower after the subjects consumed energy drink and alcohol before exercise, than after exercise alone. The healthy subjects developed blunted cardiac autonomic modulation after exercising when they had consumed energy drinks mixed with alcohol. Although they did not develop any significant arrhythmia, individuals predisposed to arrhythmia by congenital or other rhythm disorders could have an increased risk for malignant cardiac arrhythmia in similar situations.

Variation in dietary intake and physical activity pattern as predictors of change in body mass index (BMI) Z-score among Brazilian adolescents.

PubMed

Enes, Carla C; Slater, Betzabeth

2013-06-01

To assess whether changes in dietary intake and physical activity pattern are associated with the annual body mass index (BMI) z-score change among adolescents. The study was conducted in public schools in the city of Piracicaba, Sao Paulo, Brazil, with a probabilistic sample of 431 adolescents participating in wave I (2004) (hereafter, baseline) and 299 in wave II (2005) (hereafter, follow-up). BMI, usual food intake, physical activity, screen time, sexual maturation and demographic variables were assessed twice. The association between annual change in food intake, physical activity, screen time, and annual BMI z-score changes were assessed by multiple regression. The study showed a positive variation in BMI z-score over one-year. Among variables related to physical activity pattern only playing videogame and using computer increased over the year. The intake of fruits and vegetables and sugar-sweetened beverages increased over one year, while the others variables showed a reduction. An increased consumption of fatty foods (β = 0.04, p = 0.04) and sweetened natural fruit juices (β = 0.05, p = 0.03) was positively associated with the rise in BMI z-score. Unhealthy dietary habits can predict the BMI z-score gain more than the physical activity pattern. The intake of fatty foods and sweetened fruit juices is associated with the BMI z-score over one year.

Predicting folic acid intake among college students.

PubMed

Lane, Susan H; Hines, Annette; Krowchuk, Heidi

2015-01-01

Annually in the United States, approximately 3,000 babies are born with neural tube defects (NTDs). Folic acid supplementation can reduce NTDs by 50% to 70%. Despite recommendations for folic acid intake, only 30% of women ages 18 to 24 report folic acid supplementation and 6% have knowledge of when to take folic acid. There is little information regarding lifestyle factors that correlate with consuming folic acid. The purpose was to describe folic acid consumption among college students; and explore the relationship between folic acid intake and the variables of: age, gender, year in college, alcohol and tobacco use, and vitamin supplement intake. This was a descriptive study with secondary analysis of data from 1,921 college-aged student participants in North Carolina who took part in a pretest/posttest-designed intervention to increase folic acid consumption and knowledge. Surveys included demographic, lifestyle, folic acid knowledge, and consumption questions adapted from the Centers for Disease Control and Prevention questionnaire. Quantitative analyses included descriptive statistics and logistic regression. Of the 1,921 college students, 83.3% reported taking a vitamin supplement, but only 47.6% stated that the vitamin contained folic acid. A relationship was found between age, year in school, gender, and vitamin intake. Lifestyle variables were not significant predictors of folic acid consumption. Identification of variables associated with folic acid intake, marketing, and education can be focused to increase supplementation levels, and ultimately reduce the number of NTDs.

Experiments on the enhancement of compressible mixing via streamwise vorticity. II - Vortex strength assessment and seed particle dynamics

NASA Technical Reports Server (NTRS)

Naughton, J. W.; Cattafesta, L. N.; Settles, G. S.

1993-01-01

The effect of streamwise vorticity on compressible axisymmetric mixing layers is examined using vortex strength assessment and seed particle dynamics analysis. Experimental results indicate that the particles faithfully represent the dynamics of the turbulent swirling flow. A comparison of the previously determined mixing layer growth rates with the present vortex strength data reveals that the increase of turbulent mixing up to 60 percent scales with the degree of swirl. The mixing enhancement appears to be independent of the compressibility level of the mixing layer.

Combustor with fuel preparation chambers

NASA Technical Reports Server (NTRS)

Zelina, Joseph (Inventor); Myers, Geoffrey D. (Inventor); Srinivasan, Ram (Inventor); Reynolds, Robert S. (Inventor)

2001-01-01

An annular combustor having fuel preparation chambers mounted in the dome of the combustor. The fuel preparation chamber comprises an annular wall extending axially from an inlet to an exit that defines a mixing chamber. Mounted to the inlet are an air swirler and a fuel atomizer. The air swirler provides swirled air to the mixing chamber while the atomizer provides a fuel spray. On the downstream side of the exit, the fuel preparation chamber has an inwardly extending conical wall that compresses the swirling mixture of fuel and air exiting the mixing chamber.

Radial inlet guide vanes for a combustor

DOEpatents

Zuo, Baifang; Simons, Derrick; York, William; Ziminsky, Willy S

2013-02-12

A combustor may include an interior flow path therethrough, a number of fuel nozzles in communication with the interior flow path, and an inlet guide vane system positioned about the interior flow path to create a swirled flow therein. The inlet guide vane system may include a number of windows positioned circumferentially around the fuel nozzles. The inlet guide vane system may also include a number of inlet guide vanes positioned circumferentially around the fuel nozzles and adjacent to the windows to create a swirled flow within the interior flow path.

Separation Of Liquid And Gas In Zero Gravity

NASA Technical Reports Server (NTRS)

Howard, Frank S.; Fraser, Wilson S.

1991-01-01

Pair of reports describe scheme for separating liquid from gas so liquid could be pumped. Designed to operate in absence of gravitation. Jet of liquid, gas, or liquid/gas mixture fed circumferentially into cylindrical tank filled with liquid/gas mixture. Jet starts liquid swirling. Swirling motion centrifugally separates liquid from gas. Liquid then pumped from tank at point approximately diametrically opposite point of injection of jet. Vortex phase separator replaces such devices as bladders and screens. Requires no components inside tank. Pumps for gas and liquid outside tank and easily accessible for maintenance and repairs.

Kinematic α tensors and dynamo mechanisms in a von Kármán swirling flow.

PubMed

Ravelet, F; Dubrulle, B; Daviaud, F; Ratié, P-A

2012-07-13

We provide experimental and numerical evidence of in-blades vortices in the von Kármán swirling flow. We estimate the associated kinematic α-effect tensor and show that it is compatible with recent models of the von Kármán sodium (VKS) dynamo. We further show that depending on the relative frequency of the two impellers, the dominant dynamo mechanism may switch from α2 to α - Ω dynamo. We discuss some implications of these results for VKS experiments.

Predicting physical activity and fruit and vegetable intake in adolescents: a test of the information, motivation, behavioral skills model.

PubMed

Kelly, Stephanie; Melnyk, Bernadette Mazurek; Belyea, Michael

2012-04-01

Most adolescents do not meet national recommendations regarding physical activity and/or the intake of fruits and vegetables. The purpose of this study was to explore whether variables in the information, motivation, behavioral skills (IMB) model of health promotion predicted physical activity and fruit and vegetable intake in 404 adolescents from 2 high schools in the Southwest United States using structural equation modeling (SEM). The SEM models included theoretical constructs, contextual variables, and moderators. The theoretical relationships in the IMB model were confirmed and were moderated by gender and race. Interventions that incorporate cognitive-behavioral skills building may be a key factor for promoting physical activity as well as fruit and vegetable intake in adolescents. Copyright © 2012 Wiley Periodicals, Inc.

Identification of Urinary Polyphenol Metabolite Patterns Associated with Polyphenol-Rich Food Intake in Adults from Four European Countries.

PubMed

Noh, Hwayoung; Freisling, Heinz; Assi, Nada; Zamora-Ros, Raul; Achaintre, David; Affret, Aurélie; Mancini, Francesca; Boutron-Ruault, Marie-Christine; Flögel, Anna; Boeing, Heiner; Kühn, Tilman; Schübel, Ruth; Trichopoulou, Antonia; Naska, Androniki; Kritikou, Maria; Palli, Domenico; Pala, Valeria; Tumino, Rosario; Ricceri, Fulvio; Santucci de Magistris, Maria; Cross, Amanda; Slimani, Nadia; Scalbert, Augustin; Ferrari, Pietro

2017-07-25

We identified urinary polyphenol metabolite patterns by a novel algorithm that combines dimension reduction and variable selection methods to explain polyphenol-rich food intake, and compared their respective performance with that of single biomarkers in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. The study included 475 adults from four European countries (Germany, France, Italy, and Greece). Dietary intakes were assessed with 24-h dietary recalls (24-HDR) and dietary questionnaires (DQ). Thirty-four polyphenols were measured by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS-MS) in 24-h urine. Reduced rank regression-based variable importance in projection (RRR-VIP) and least absolute shrinkage and selection operator (LASSO) methods were used to select polyphenol metabolites. Reduced rank regression (RRR) was then used to identify patterns in these metabolites, maximizing the explained variability in intake of pre-selected polyphenol-rich foods. The performance of RRR models was evaluated using internal cross-validation to control for over-optimistic findings from over-fitting. High performance was observed for explaining recent intake (24-HDR) of red wine ( r = 0.65; AUC = 89.1%), coffee ( r = 0.51; AUC = 89.1%), and olives ( r = 0.35; AUC = 82.2%). These metabolite patterns performed better or equally well compared to single polyphenol biomarkers. Neither metabolite patterns nor single biomarkers performed well in explaining habitual intake (as reported in the DQ) of polyphenol-rich foods. This proposed strategy of biomarker pattern identification has the potential of expanding the currently still limited list of available dietary intake biomarkers.

Habitual sleep variability, not sleep duration, is associated with caloric intake in adolescents

PubMed Central

Fan, HE; BIXLER, Edward O.; BERG, Arthur; KAWASAWA, Yuka IMAMURA; VGONTZAS, Alexandros N.; FERNANDEZ-MENDOZA, Julio; YANOSKY, Jeff; LIAO, Duanping

2015-01-01

Objective To investigate the associations between objectively-measured habitual sleep duration (HSD), habitual sleep variability (HSV) and energy and snack intake in adolescents. Methods We used data from 324 adolescents participated in the Penn State Child Cohort follow-up examination. Actigraphy was used over 7 consecutive nights to estimate nightly sleep duration. The 7-night mean and standard deviation of sleep duration were used to represent HSD and HSV, respectively. Youth/Adolescent Food Frequency Questionnaire was used to obtain daily average total energy, protein, fat, carbohydrates intakes, and number of snacks consumed. Linear regression models were used to investigate the associations between habitual sleep patterns and caloric, protein, fat, and carbohydrates intakes. Proportional odds models were used to associate habitual sleep patterns and snack consumption. Results After adjusting for age, sex, race, BMI percentile, and smoking status, increased HSV was associated with higher energy intake, particularly from fat and carbohydrate. For example, with 1-hour increase in HSV, there was 170 (66) kcal increase in daily total energy intake. Increased HSV also related to increased snack consumption, especially snacks consumed after dinner. For instance, 1 hour increase in HSV was associated with 65% and 94% higher odds of consuming more snacks after dinner during school/work days and weekends/vacation days, respectively. Neither energy intake nor snack consumption was significantly related to HSD. Conclusion High variability in habitual sleep duration, not habitual sleep duration, is related to increased energy and food consumptions in adolescents. Maintaining a regular sleep pattern may decrease the risk of obesity in adolescents. PMID:26002758

APOA2 -256T>C polymorphism interacts with saturated fatty acids intake to affect anthropometric and hormonal variables in type 2 diabetic patients.

PubMed

Basiri, Marjan Ghane; Sotoudeh, Gity; Alvandi, Ehsan; Djalali, Mahmood; Eshraghian, Mohammad Reza; Noorshahi, Neda; Koohdani, Fariba

2015-05-01

Recent studies have established the interaction between APOA2 -256T>C polymorphism and dietary saturated fatty acids intake in relation to obesity on healthy individuals. In the current study, we investigate the effects of this interaction on anthropometric variables and serum levels of leptin and ghrelin in patients with type 2 diabetes. In this cross-sectional study, 737 patients with type 2 diabetes mellitus (290 males and 447 females) were recruited from diabetes clinics in Tehran. The usual dietary intake of all participants during the last year was obtained by validated semiquantitative food frequency questionnaire. APOA2 genotyping was performed by real-time PCR on genomic DNA. No significant relation was obtained by univariate analysis between anthropometric variables and APOA2 genotypes. However, after adjusting for age, gender, physical activity and total energy intake, we identified a significant interaction between APOA2-saturated fatty acids intake and body mass index (BMI). After adjusting for potential confounders, serum levels of ghrelin in CC genotype patients were significantly higher than T allele carriers (p = 0.03), whereas the case with leptin did not reveal a significant difference. The result of this study confirmed the interaction between APOA2 -256T>C polymorphism and SFAs intake with BMI in type 2 diabetic patients. In fact, homozygous patients for the C allele with high saturated fatty acids intake had higher BMI. The APOA2 -256T>C polymorphism was associated with elevated levels of serum ghrelin.

Numerical Modeling of a Vortex Stabilized Arcjet. Ph.D. Thesis, 1991 Final Report

NASA Technical Reports Server (NTRS)

Pawlas, Gary E.

1992-01-01

Arcjet thrusters are being actively considered for use in Earth orbit maneuvering applications. Experimental studies are currently the chief means of determining an optimal thruster configuration. Earlier numerical studies have failed to include all of the effects found in typical arcjets including complex geometries, viscosity, and swirling flow. Arcjet geometries are large area ratio converging nozzles with centerbodies in the subsonic portion of the nozzle. The nozzle walls serve as the anode while the centerbody functions as the cathode. Viscous effects are important because the Reynolds number, based on the throat radius, is typically less than 1,000. Experimental studies have shown that a swirl or circumferential velocity component stabilizes a constricted arc. This dissertation describes the equations governing flow through a constricted arcjet thruster. An assumption that the flowfield is in local thermodynamic equilibrium leads to a single fluid plasma temperature model. An order of magnitude analysis reveals the governing fluid mechanics equations are uncoupled from the electromagnetic field equations. A numerical method is developed to solve the governing fluid mechanics equations, the Thin Layer Navier-Stokes equations. A coordinate transformation is employed in deriving the governing equations to simplify the application of boundary conditions in complex geometries. An axisymmetric formulation is employed to include the swirl velocity component as well as the axial and radial velocity components. The numerical method is an implicit finite-volume technique and allows for large time steps to reach a converged steady-state solution. The inviscid fluxes are flux-split, and Gauss-Seidel line relaxation is used to accelerate convergence. Converging-diverging nozzles with exit-to-throat area ratios up to 100:1 and annular nozzles were examined. Quantities examined included Mach number and static wall pressure distributions, and oblique shock structures. As the level of swirl and viscosity in the flowfield increased the mass flow rate and thrust decreased. The technique was used to predict the flow through a typical arcjet thruster geometry. Results indicate swirl and viscosity play an important role in the complex geometry of an arcjet.

Numerical modeling of a vortex stabilized arcjet

NASA Astrophysics Data System (ADS)

Pawlas, Gary E.

1992-11-01

Arcjet thrusters are being actively considered for use in Earth orbit maneuvering applications. Experimental studies are currently the chief means of determining an optimal thruster configuration. Earlier numerical studies have failed to include all of the effects found in typical arcjets including complex geometries, viscosity, and swirling flow. Arcjet geometries are large area ratio converging nozzles with centerbodies in the subsonic portion of the nozzle. The nozzle walls serve as the anode while the centerbody functions as the cathode. Viscous effects are important because the Reynolds number, based on the throat radius, is typically less than 1,000. Experimental studies have shown that a swirl or circumferential velocity component stabilizes a constricted arc. This dissertation describes the equations governing flow through a constricted arcjet thruster. An assumption that the flowfield is in local thermodynamic equilibrium leads to a single fluid plasma temperature model. An order of magnitude analysis reveals the governing fluid mechanics equations are uncoupled from the electromagnetic field equations. A numerical method is developed to solve the governing fluid mechanics equations, the Thin Layer Navier-Stokes equations. A coordinate transformation is employed in deriving the governing equations to simplify the application of boundary conditions in complex geometries. An axisymmetric formulation is employed to include the swirl velocity component as well as the axial and radial velocity components. The numerical method is an implicit finite-volume technique and allows for large time steps to reach a converged steady-state solution. The inviscid fluxes are flux-split, and Gauss-Seidel line relaxation is used to accelerate convergence. Converging-diverging nozzles with exit-to-throat area ratios up to 100:1 and annular nozzles were examined. Quantities examined included Mach number and static wall pressure distributions, and oblique shock structures. As the level of swirl and viscosity in the flowfield increased the mass flow rate and thrust decreased.

Continuous glucose monitoring to assess the ecologic validity of dietary glycemic index and glycemic load123

PubMed Central

Ebbeling, Cara B; Wadden, Thomas A; Ludwig, David S

2011-01-01

Background: The circumstances under which the glycemic index (GI) and glycemic load (GL) are derived do not reflect real-world eating behavior. Thus, the ecologic validity of these constructs is incompletely known. Objective: This study examined the relation of dietary intake to glycemic response when foods are consumed under free-living conditions. Design: Participants were 26 overweight or obese adults with type 2 diabetes who participated in a randomized trial of lifestyle modification. The current study includes baseline data, before initiation of the intervention. Participants wore a continuous glucose monitor and simultaneously kept a food diary for 3 d. The dietary variables included GI, GL, and intakes of energy, fat, protein, carbohydrate, sugars, and fiber. The glycemic response variables included AUC, mean and SD of continuous glucose monitoring (CGM) values, percentage of CGM values in euglycemic and hyperglycemic ranges, and mean amplitude of glycemic excursions. Relations between daily dietary intake and glycemic outcomes were examined. Results: Data were available from 41 d of monitoring. Partial correlations, controlled for energy intake, indicated that GI or GL was significantly associated with each glycemic response outcome. In multivariate analyses, dietary GI accounted for 10% to 18% of the variance in each glycemic variable, independent of energy and carbohydrate intakes (P < 0.01). Conclusions: The data support the ecologic validity of the GI and GL constructs in free-living obese adults with type 2 diabetes. GI was the strongest and most consistent independent predictor of glycemic stability and variability. PMID:22071699

CFD Simulations of Supersonic Highly Swirling Flow Exiting a Turbine Vane Row Compared with Experimental Observations

NASA Technical Reports Server (NTRS)

West, Jeff S.; Richardson, Brian R.; Schmauch, Preston; Kenny, Robert J.

2011-01-01

Marshall Space Flight Center (MSFC) has been heavily involved in developing the J2-X engine. The Center has been testing a Work Horse Gas Generator (WHGG) to supply gas products to J2-X turbine components at realistic flight-like operating conditions. Three-dimensional time accurate CFD simulations and analytical fluid analysis have been performed to support WHGG tests at MSFC. The general purpose CFD program LOCI/Chem was utilized to simulate flow of products from the WHGG through a turbine manifold, a stationary row of turbine vanes, into a Can and orifice assembly used to control the back pressure at the turbine vane row and finally through an aspirator plate and flame bucket. Simulations showed that supersonic swirling flow downstream of the turbine imparted a much higher pressure on the Can wall than expected for a non-swirling flow. This result was verified by developing an analytical model that predicts wall pressure due to swirling flow. The CFD simulations predicted that the higher downstream pressure would cause the pressure drop across the nozzle row to be approximately half the value of the test objective. With CFD support, a redesign of the Can orifice and aspirator plate was performed. WHGG experimental results and observations compared well with pre-test and post-test CFD simulations. CFD simulations for both quasi-static and transient test conditions correctly predicted the pressure environment downstream of the turbine row and the behavior of the gas generator product plume as it exited the WHGG test article, impacted the flame bucket and interacted with the external environment.

Individual differences affecting caffeine intake. Analysis of consumption behaviours for different times of day and caffeine sources.

PubMed

Penolazzi, Barbara; Natale, Vincenzo; Leone, Luigi; Russo, Paolo Maria

2012-06-01

The main purpose of the present study was to investigate the individual variables contributing to determine the high variability in the consumption behaviours of caffeine, a psychoactive substance which is still poorly investigated in comparison with other drugs. The effects of a large set of specific personality traits (i.e., Impulsivity, Sensation Seeking, Anxiety, Reward Sensitivity and Circadian Preference) were compared along with some relevant socio-demographic variables (i.e., gender and age) and cigarette smoking behaviour. Analyses revealed that daily caffeine intake was significantly higher for males, older people, participants smoking more cigarettes and showing higher scores on Impulsivity, Sensation Seeking and a facet of Reward Sensitivity. However, more detailed analyses showed that different patterns of individual variables predicted caffeine consumption when the times of day and the caffeine sources were considered. The present results suggest that such detailed analyses are required to detect the critical predictive variables that could be obscured when only total caffeine intake during the entire day is considered. Copyright © 2012 Elsevier Ltd. All rights reserved.

Secondary analyses of data from four studies with fourth-grade children show that sex, race, amounts eaten of standardized portions, and energy content given in trades explain the positive relationship between BMI and energy intake at school-provided meals

PubMed Central

Baxter, Suzanne Domel; Paxton-Aiken, Amy E.; Tebbs, Joshua M.; Royer, Julie A.; Guinn, Caroline H.; Finney, Christopher J.

2012-01-01

Results from a 2012 article showed a positive relationship between children’s body mass index (BMI) and energy intake at school-provided meals. To help explain that positive relationship, secondary analyses investigated 1) whether the relationship differed by sex and race, and 2) the relationship between BMI and six aspects of school-provided meals—amounts eaten of standardized portions, energy content given in trades, energy intake received in trades, energy intake from flavored milk, energy intake from a la carte ice cream, and breakfast type. Data were from four studies conducted one per school year (1999–2000 to 2002–2003). Fourth-grade children (n=328; 50% female; 54% Black) from 13 schools total were observed eating school-provided breakfast and lunch on one to three days per child for 1,178 total meals (50% breakfast). Children were weighed and measured. Marginal regression models were fit using BMI as the dependent variable. For Purpose One, independent variables were energy intake at school-provided meals, sex, race, age, and study; additional models included interaction terms involving energy intake and sex/race. For Purpose Two, independent variables were the six aspects of school-provided meals, sex, race, age, and study. The relationship between BMI and energy intake at school-provided meals differed by sex (p<0.0001; stronger for females) and race (p=0.0063; stronger for Black children). BMI was positively related to amounts eaten of standardized portions (p<0.0001) and negatively related to energy content given in trades (p=0.0052). Explaining the positive relationship between BMI and energy intake at school-provided meals may contribute to school-based obesity prevention efforts. PMID:23084638

Secondary analyses of data from 4 studies with fourth-grade children show that sex, race, amounts eaten of standardized portions, and energy content given in trades explain the positive relationship between body mass index and energy intake at school-provided meals.

PubMed

Baxter, Suzanne Domel; Paxton-Aiken, Amy E; Tebbs, Joshua M; Royer, Julie A; Guinn, Caroline H; Finney, Christopher J

2012-09-01

Results from a 2012 article showed a positive relationship between children's body mass index (BMI) and energy intake at school-provided meals. To help explain that positive relationship, secondary analyses investigated (1) whether the relationship differed by sex and race and (2) the relationship between BMI and 6 aspects of school-provided meals--amounts eaten of standardized portions, energy content given in trades, energy intake received in trades, energy intake from flavored milk, energy intake from a la carte ice cream, and breakfast type. Data were from 4 studies conducted 1 per school year (1999-2000 to 2002-2003). Fourth-grade children (n = 328; 50% female; 54% black) from 13 schools total were observed eating school-provided breakfast and lunch on 1 to 3 days per child for 1178 total meals (50% breakfast). Children were weighed and measured. Marginal regression models were fit using BMI as the dependent variable. For purpose 1, independent variables were energy intake at school-provided meals, sex, race, age, and study; additional models included interaction terms involving energy intake and sex/race. For purpose 2, independent variables were the 6 aspects of school-provided meals, sex, race, age, and study. The relationship between BMI and energy intake at school-provided meals differed by sex (P < .0001; stronger for females) and race (P = .0063; stronger for black children). BMI was positively related to amounts eaten of standardized portions (P < .0001) and negatively related to energy content given in trades (P = .0052). Explaining the positive relationship between BMI and energy intake at school-provided meals may contribute to school-based obesity prevention efforts. Copyright © 2012 Elsevier Inc. All rights reserved.

Nonlinear axisymmetric and three-dimensional vorticity dynamics in a swirling jet model

NASA Technical Reports Server (NTRS)

Martin, J. E.; Meiburg, E.

1996-01-01

The mechanisms of vorticity concentration, reorientation, and stretching are investigated in a simplified swirling jet model, consisting of a line vortex along the jet axis surrounded by a jet shear layer with both azimuthal and streamwise vorticity. Inviscid three-dimensional vortex dynamics simulations demonstrate the nonlinear interaction and competition between a centrifugal instability and Kelvin-Helmholtz instabilities feeding on both components of the base flow vorticity. Under axisymmetric flow conditions, it is found that the swirl leads to the emergence of counterrotating vortex rings, whose circulation, in the absence of viscosity, can grow without bounds. Scaling laws are provided for the growth of these rings, which trigger a pinch-off mechanism resulting in a strong decrease of the local jet diameter. In the presence of an azimuthal disturbance, the nonlinear evolution of the flow depends strongly on the initial ratio of the azimuthal and axisymmetric perturbation amplitudes. The long term dynamics of the jet can be dominated by counterrotating vortex rings connected by braid vortices, by like-signed rings and streamwise braid vortices, or by wavy streamwise vortices alone.

The ventralizing activity of Radar, a maternally expressed bone morphogenetic protein, reveals complex bone morphogenetic protein interactions controlling dorso-ventral patterning in zebrafish.

PubMed

Goutel, C; Kishimoto, Y; Schulte-Merker, S; Rosa, F

2000-12-01

In Xenopus and zebrafish, BMP2, 4 and 7 have been implicated, after the onset of zygotic expression, in inducing and maintaining ventro-lateral cell fate during early development. We provide evidence here that a maternally expressed bone morphogenetic protein (BMP), Radar, may control early ventral specification in zebrafish. We show that Radar ventralizes zebrafish embryos and induces the early expression of bmp2b and bmp4. The analysis of Radar overexpression in both swirl/bmp2b mutants and embryos expressing truncated BMP receptors shows that Radar-induced ventralization is dependent on functional BMP2/4 pathways, and may initially rely on an Alk6-related signaling pathway. Finally, we show that while radar-injected swirl embryos still exhibit a strongly dorsalized phenotype, the overexpression of Radar into swirl/bmp2b mutant embryos restores ventral marker expression, including bmp4 expression. Our results suggest that a complex regulation of different BMP pathways controls dorso-ventral (DV) patterning from early cleavage stages until somitogenesis.

Saturn Watercolor Swirls

NASA Image and Video Library

2016-11-14

Saturn's north polar region displays its beautiful bands and swirls, which somewhat resemble the brushwork in a watercolor painting. Each latitudinal band represents air flowing at different speeds, and clouds at different heights, compared to neighboring bands. Where they meet and flow past each other, the bands' interactions produce many eddies and swirls. The northern polar region of Saturn is dominated by the famous hexagon shape (see PIA11682) which itself circumscribes the northern polar vortex -- seen as a dark spot at the planet's pole in the above image-- which is understood to the be eye of a hurricane-like storm (PIA14946). This view looks toward the sunlit side of the rings from about 20 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on Sept. 5, 2016 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 728 nanometers. The view was obtained at a distance of approximately 890,000 miles (1.4 million kilometers) from Saturn. Image scale is 53 miles (86 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA20507

Time-resolved PIV investigation of flashback in stratified swirl flames of hydrogen-rich fuel

NASA Astrophysics Data System (ADS)

Ranjan, Rakesh; Clemens, Noel

2016-11-01

Hydrogen is one of the promising alternative fuels to achieve greener power generation. However, susceptibility of flashback in swirl flames of hydrogen-rich fuels acts as a major barrier to its adoption in gas turbine combustors. The current study seeks to understand the flow-flame interaction during the flashback of the hydrogen-rich flame in stratified conditions. Flashback experiments are conducted with a model combustor equipped with an axial swirler and a center-body. Fuel is injected in the main swirl flow via the fuel ports on the swirler vanes. To achieve mean radial stratification, these fuel ports are located at a radial location closer to the outer wall of the mixing tube. Stratification in the flow is assessed by employing Anisole PLIF imaging. Flashback is triggered by a rapid increase in the global equivalence ratio. The upstream propagation of the flame is investigated by employing time-resolved stereoscopic PIV and chemiluminescence imaging. Stratification leads to substantially different flame propagation behavior as well as increased flame surface wrinkling. We gratefully acknowledge the sponsorship by the DOE NETL under Grant DEFC2611-FE0007107.

Swirling Flow Computation at the Trailing Edge of Radial-Axial Hydraulic Turbines

NASA Astrophysics Data System (ADS)

Susan-Resiga, Romeo; Muntean, Sebastian; Popescu, Constantin

2016-11-01

Modern hydraulic turbines require optimized runners within a range of operating points with respect to minimum weighted average draft tube losses and/or flow instabilities. Tractable optimization methodologies must include realistic estimations of the swirling flow exiting the runner and further ingested by the draft tube, prior to runner design. The paper presents a new mathematical model and the associated numerical algorithm for computing the swirling flow at the trailing edge of Francis turbine runner, operated at arbitrary discharge. The general turbomachinery throughflow theory is particularized for an arbitrary hub-to-shroud line in the meridian half-plane and the resulting boundary value problem is solved with the finite element method. The results obtained with the present model are validated against full 3D runner flow computations within a range of discharge value. The mathematical model incorporates the full information for the relative flow direction, as well as the curvatures of the hub-to-shroud line and meridian streamlines, respectively. It is shown that the flow direction can be frozen within a range of operating points in the neighborhood of the best efficiency regime.

Gas sampling method for determining pollutant concentrations in the flame zone of two swirl-can combustor modules

NASA Technical Reports Server (NTRS)

Duerr, R. A.

1975-01-01

A gas sampling probe and traversing mechanism were developed to obtain detailed measurements of gaseous pollutant concentrations in the primary and mixing regions of combustors in order to better understand how pollutants are formed. The gas sampling probe was actuated by a three-degree-of-freedom traversing mechanism and the samples obtained were analyzed by an on-line gas analysis system. The pollutants in the flame zone of two different swirl-can combustor modules were measured at an inlet-air temperature of 590 K, pressure of 6 atmospheres, and reference velocities of 23 and 30 meters per second at a fuel-air ratio of 0.02. Typical results show large spatial gradients in the gaseous pollutant concentration close to the swirl-can module. Average concentrations of unburned hydrocarbons and carbon monoxide decrease rapidly in the downstream wake regions of each module. By careful and detailed probing, the effect of various module design features on pollutant formation can be assessed. The techniques presently developed seem adequate to obtain the desired information.

The effects of streamline curvature and swirl on turbulent flows in curved ducts

NASA Technical Reports Server (NTRS)

Cheng, Chih-Hsiung; Farokhi, Saeed

1990-01-01

A technique for improving the numerical predictions of turbulent flows with the effect of streamline curvature is developed. Separated flows, the flow in a curved duct, and swirling flows are examples of flow fields where streamline curvature plays a dominant role. A comprehensive literature review on the effect of streamline curvature was conducted. New algebraic formulations for the eddy viscosity incorporating the kappa-epsilon turbulence model are proposed to account for various effects of streamline curvature. The loci of flow reversal of the separated flows over various backward-facing steps are employed to test the capability of the proposed turbulence model in capturing the effect of local curvature. The inclusion of the effect of longitudinal curvature in the proposed turbulence model is validated by predicting the distributions of the static pressure coefficients in an S-bend duct and in 180 degree turn-around ducts. The proposed turbulence model embedded with transverse curvature modification is substantiated by predicting the decay of the axial velocities in the confined swirling flows. The numerical predictions of different curvature effects by the proposed turbulence models are also reported.

Numerical Investigation of a Novel Microscale Swirling Jet Reactor for Medical Sensor Applications

NASA Astrophysics Data System (ADS)

Ogus, G.; Baelmans, M.; Lammertyn, J.; Vanierschot, M.

2018-03-01

A microscale swirler and corresponding reactor for a recent detection and analysis tool for healthcare applications, Fiber optic-surface plasmon resonance (FO-SPR), is presented in this study. The sensor is a 400 μm diameter needle that works as a detector for certain particles. Currently, the detection process relies on diffusion of particles towards the sensor and hence diagnostic time is rather long. The aim of this study is to decrease that diagnostic time by introducing convective mixing in the reactor by means of a swirling inlet flow. This will increase the particle deposition on the FO-SPR sensor and hence an increase in detection rate, as this rate strongly depends on the aimed particle concentration near the sensor. As the flow rates are rather low and the length scales are small, the flow in such reactors is laminar. In this study, robustly controllable mixing features of a swirling jet flow is used to increase the particle concentration near the sensor. A numerical analysis (CFD) is performed to characterize the flow and a detailed analysis of flow structures depending on the flow rate are reported.

Particle-laden swirling free jets: Measurements and predictions

NASA Technical Reports Server (NTRS)

Bulzan, D. L.; Shuen, J.-S.; Faeth, G. M.

1987-01-01

A theoretical and experimental investigation of single-phase and particle-laden weakly swirling jets was conducted. The jets were injected vertically downward from a 19 mm diameter tube with swirl numbers ranging from 0 to 0.33. The particle-laden jets had a single loading ratio (0.2) with particles having a SMD of 39 microns. Mean and fluctuating properties of both phases were measured using nonintrusive laser based methods while particle mass flux was measured using an isokinetic sampling probe. The continuous phase was analyzed using both a baseline kappa-epsilon turbulence model and an extended version with modifications based on the flux Richardson number to account for effects of streamline curvature. To highlight effects of interphase transport rates and particle/turbulence interactions, effects of the particles were analyzed as follows: (1) locally homogeneous flow (LHF) analysis, where interphase transport rates are assumed to be infinitely fast; (2) deterministic separated flow (DSF) analysis, where finite interphase transport rates are considered but particle/turbulence interactions are ignored; and (3) stochastic separated flow (SSF) analysis, where both effects are considered using random-walk computations.

From Dust Devil to Sustainable Swirling Wind Energy

NASA Astrophysics Data System (ADS)

Zhang, Mingxu; Luo, Xilian; Li, Tianyu; Zhang, Liyuan; Meng, Xiangzhao; Kase, Kiwamu; Wada, Satoshi; Yu, Chuck Wah; Gu, Zhaolin

2015-02-01

Dust devils are common but meteorologically unique phenomena on Earth and on Mars. The phenomenon produces a vertical vortex motion in the atmosphere boundary layer and often occurs in hot desert regions, especially in the afternoons from late spring to early summer. Dust devils usually contain abundant wind energy, for example, a maximum swirling wind velocity of up to 25 m/s, with a 15 m/s maximum vertical velocity and 5 m/s maximum near-surface horizontal velocity can be formed. The occurrences of dust devils cannot be used for energy generation because these are generally random and short-lived. Here, a concept of sustained dust-devil-like whirlwind is proposed for the energy generation. A prototype of a circular shed with pre-rotation vanes has been devised to generate the whirlwind flow by heating the air inflow into the circular shed. The pre-rotation vanes can provide the air inflow with angular momentum. The results of numerical simulations and experiment illustrate a promising potential of the circular shed for generating swirling wind energy via the collection of low-temperature solar energy.

Flow Structure Comparison for Two 7-Point LDI Configurations

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Tacina, Kathleen M.

2017-01-01

This paper presents a comparison primarily of the 2-D velocity profiles in the non-burning system; and for the luminescent flame structure for a 7-point Lean Direct Injector (LDI). This circular LDI array consists of a center element surrounded by six outer elements spaced 60 degrees apart; the spacing between all adjacent elements is the same. Each element consists of simplex atomizer that injects at the throat of a converging-diverging venturi, and an axial swirler upstream of the venturi throat to generate swirl. The two configurations were: 1) one which consists of all 60 co-swirling axial air swirlers, and; 2) one configuration which uses a 60 swirler in the center, surrounded by counter-swirling 45 swirlers. Testing was done at 5 atm and an inlet temperature of 800F. Two air reference velocities were considered in the cold flow measurements and one common air flow condition for the burning case.The 2D velocity profiles were determined using particle image velocimetry and the flame structure was determined using high speed photography.

Five-hole pitot probe time-mean velocity measurements in confined swirling flows

NASA Technical Reports Server (NTRS)

Yoon, H. K.; Lilley, D. G.

1983-01-01

Nonswirling and swirling nonreacting flows in an axisymmetric test section with an expansion ratio D/d = 2, which may be equipped with contraction nozzles of area ratios 2 and 4, are investigated. The effects of a number of geometric parameters on the flow-field are investigated, among them side-wall expansion angles of 90 and 45 deg, swirl vane angles of 0, 38, 45, 60, and 70 deg, and contraction nozzle locations L/D = 1 and 2 (if present). Data are acquired by means of a five-hole pitot probe enabling three time-mean velocity components in the axial, radial, and azimuthal directions to be measured. The velocities are extensively plotted and artistic impressions of recirculation zones are set forth. The presence of a swirler is found to shorten the corner recirculation zone and to generate a central recirculation zone followed by a precessing vortex core. A gradual inlet expansion has the effect of encouraging the flow to remain close to the sidewall and shortening the extent of the corner recirculation zone in all cases investigated.

Experiments on opposed lateral jets injected into swirling crossflow. M.S. Thesis Final Report

NASA Technical Reports Server (NTRS)

Mcmurry, C. B.; Lilley, D. G.

1986-01-01

Experiments have been conducted to obtain the time-mean and turbulent quantities of opposed lateral jets in a low speed, nonreacting flowfield. A jet-to-crossflow velocity ratio of R = v sub J/u sub 0 = 4 was used throughout the experiments, with swirl vane angles of d = 0 (swirler removed), 45 and 70 deg used with the crossflow. Flow visualization techniques used were neutrally-buoyant helium-filled soap bubbles and multispark photography in order to obtain the gross flowfield characteristics. Measurements of time-mean and turbulent quantities were obtained utilizing a six-orientation single hot-wire technique. For the nonswirling case, the jets were found not to penetrate past the test-section centerline, in contrast to the single lateral jet with the same jet-to-crossflow velocity ratio. In the swirling cases, the crossflow remains in a narrow region near the wall of the test section. The opposed jets are swept from their vertical courses into spiral trajectories close to the confining walls. Extensive results are presented in r-x plane plots.

Heat-exchanger concepts for neutral-beam calorimeters

NASA Astrophysics Data System (ADS)

Thompson, C. C.; Polk, D. H.; McFarlin, D. J.; Stone, R.

1981-10-01

Advanced cooling concepts that permit the design of water cooled heat exchangers for use as calorimeters and beam dumps for advanced neutral beam injection systems were evaluated. Water cooling techniques ranging from pool boiling to high pressure, high velocity swirl flow were considered. Preliminary performance tests were carried out with copper, inconel and molybdenum tubes ranging in size from 0.19 to 0.50 in. diameter. Coolant flow configurations included: (1) smooth tube/straight flow; (2) smooth tube with swirl flow created by tangential injection of the coolant; and (3) axial flow in internally finned tubes. Additionally, the effect of tube L/D was evaluated. A CO2 laser was employed to irradiate a sector of the tube exterior wall; the laser power was incrementally increased until burnout occurred. Absorbed heat fluxes were calculated by dividing the measured coolant heat load by the area of the burn spot on the tube surface. Two six element thermopiles were used to accurately determine the coolant temperature rise. A maximum burnout heat flux near 14 kW/sq cm was obtained for the molybdenum tube swirl flow configuration.

Injector Element which Maintains a Constant Mean Spray Angle and Optimum Pressure Drop During Throttling by Varying the Geometry of Tangential Inlets

NASA Technical Reports Server (NTRS)

Trinh, Huu P. (Inventor); Myers, William Neill (Inventor)

2014-01-01

A method for determining the optimum inlet geometry of a liquid rocket engine swirl injector includes obtaining a throttleable level phase value, volume flow rate, chamber pressure, liquid propellant density, inlet injector pressure, desired target spray angle and desired target optimum delta pressure value between an inlet and a chamber for a plurality of engine stages. The tangential inlet area for each throttleable stage is calculated. The correlation between the tangential inlet areas and delta pressure values is used to calculate the spring displacement and variable inlet geometry. An injector designed using the method includes a plurality of geometrically calculated tangential inlets in an injection tube; an injection tube cap with a plurality of inlet slots slidably engages the injection tube. A pressure differential across the injector element causes the cap to slide along the injection tube and variably align the inlet slots with the tangential inlets.

Gas dynamics and mixture formation in swirled flows with precession of air flow

NASA Astrophysics Data System (ADS)

Tretyakov, V. V.; Sviridenkov, A. A.

2017-10-01

The effect of precessing air flow on the processes of mixture formation in the wake of the front winding devices of the combustion chambers is considered. Visual observations have shown that at different times the shape of the atomized jet is highly variable and has signs of precessing motion. The experimental data on the distribution of the velocity and concentration fields of the droplet fuel in the working volume of the flame tube of a typical combustion chamber are obtained. The method of calculating flows consisted in integrating the complete system of Reynolds equations written in Euler variables and closed with the two-parameter model of turbulence k-ε. Calculation of the concentration fields of droplet and vapor fuel is based on the use of models for disintegration into droplets of fuel jets, fragmentation of droplets and analysis of motion and evaporation of individual droplets in the air flow. Comparison of the calculation results with experimental data showed their good agreement.

Dedicated EGR engine with dynamic load control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayman, Alan W.; McAlpine, Robert S.; Keating, Edward J.

An internal combustion engine comprises a first engine bank and a second engine bank. A first intake valve is disposed in an intake port of a cylinder of the first engine bank, and is configured for metering the first flow of combustion air by periodically opening and closing according to a first intake valve lift and duration characteristic. A variable valve train control mechanism is configured for affecting the first intake valve lift and duration characteristic. Either a lift or duration of the first intake valve is modulated so as to satisfy an EGR control criterion.

Eating styles and energy intake in young women.

PubMed

Anschutz, Doeschka J; Van Strien, Tatjana; Van De Ven, Monique O M; Engels, Rutger C M E

2009-08-01

The aim of the present study was to examine the relations between restrained, emotional, and external eating and total energy intake, and total fat and carbohydrate intake controlling for body mass index and physical activity. The sample consisted of 475 female students. Energy intake was measured over a 1-month period using the self-report Food Frequency Questionnaire and eating styles were assessed with the Dutch Eating Behaviour Questionnaire. Structural equation modelling was used to analyze the data. The results showed that restrained eating was consistently negatively related to energy intake and fat and carbohydrate intake, whereas external eating was positively related to all dependent variables. Emotional eating was not related to energy intake or fat and carbohydrate intake. Thus, restrained eaters seem to restrict their energy intake, while external eating was found to be associated with higher levels of energy intake, especially of fat intake.

[Association between hematopoietic nutrient intake and the origin of nutritional anemia in women of childbearing age in Colombia].

PubMed

Manjarrés, Luz Mariela; Díaz, Abel; Carriquiry, Alicia

2012-01-01

Compare the nutritional origin of anemia by sociodemographic variables and analyze its association with deficient hematopoietic nutrient intake. The database of Colombia's 2005 National Survey of Nutritional Status was used. The data were obtained through complex representative sampling of the population and processed using SPSS v.15. Anemic women of childbearing age were selected and divided into two groups according to serum ferritin levels. Their customary hematopoietic nutrient intake and risk of deficiency were determined. The proportions of anemia types were compared by sociodemographic variables using the F-distribution, the Rao-Scott second order correction (P < 0.05). The association between the origin of the anemia and classification of the nutrient was analyzed using the odds ratio (OR). 595 women. Non-hypoferric anemia (67.2%) predominated, with no statistical difference by sociodemographic variable, except in the Pacific region (hypoferric anemia, 52.1%). The prevalence of deficiency in the customary intake of hematopoietic nutrients was high. There was no significant association between the deficit in consumption and the origin of the anemia. Non-hypoferric anemia was most common, with no difference by sociodemographic indicators except in the Pacific region. All the women were at high risk of deficiency in their customary hematopoietic nutrient intake, but a statistically significant association between the deficiency and the origin of the nutritional anemia was not observed. Programs to improve nutrient intake and a continued search for causes of nutritional anemia other than iron deficiency are justified.

Jupiter From Below (Enhanced Color)

NASA Image and Video Library

2017-02-08

This enhanced-color image of Jupiter's south pole and its swirling atmosphere was created by citizen scientist Roman Tkachenko using data from the JunoCam imager on NASA's Juno spacecraft. Juno acquired the image, looking directly at the Jovian south pole, on February 2, 2017, at 6:06 a.m. PST (9:06 a.m. EST) from an altitude of about 63,400 miles (102,100 kilometers) above Jupiter's cloud tops. Cyclones swirl around the south pole, and white oval storms can be seen near the limb -- the apparent edge of the planet. http://photojournal.jpl.nasa.gov/catalog/PIA21381

Jupiter's Swirling Cloud Formations

NASA Image and Video Library

2018-02-15

See swirling cloud formations in the northern area of Jupiter's north temperate belt in this new view taken by NASA's Juno spacecraft. The color-enhanced image was taken on Feb. 7 at 5:42 a.m. PST (8:42 a.m. EST), as Juno performed its eleventh close flyby of Jupiter. At the time the image was taken, the spacecraft was about 5,086 miles (8,186 kilometers) from the tops of the clouds of the planet at a latitude of 39.9 degrees. Citizen scientist Kevin M. Gill processed this image using data from the JunoCam imager. https://photojournal.jpl.nasa.gov/catalog/PIA21978

Aerothermal modeling program. Phase 2, element B: Flow interaction experiment

NASA Technical Reports Server (NTRS)

Nikjooy, M.; Mongia, H. C.; Murthy, S. N. B.; Sullivan, J. P.

1987-01-01

NASA has instituted an extensive effort to improve the design process and data base for the hot section components of gas turbine engines. The purpose of element B is to establish a benchmark quality data set that consists of measurements of the interaction of circular jets with swirling flow. Such flows are typical of those that occur in the primary zone of modern annular combustion liners. Extensive computations of the swirling flows are to be compared with the measurements for the purpose of assessing the accuracy of current physical models used to predict such flows.

Turbofan forced mixer lobe flow modeling. Part 3: Application to augment engines

NASA Technical Reports Server (NTRS)

Barber, T.; Moore, G. C.; Blatt, J. R.

1988-01-01

Military engines frequently need large quantities of thrust for short periods of time. The addition of an augmentor can provide such thrust increases but with a penalty of increased duct length and engine weight. The addition of a forced mixer to the augmentor improves performance and reduces the penalty, as well as providing a method for siting the required flame holders. In this report two augmentor concepts are investigated: a swirl-mixer augmentor and a mixer-flameholder augmentor. Several designs for each concept are included and an experimental assessment of one of the swirl-mixer augmentors is presented.

Aerothermal modeling program, phase 1

NASA Technical Reports Server (NTRS)

Srinivasan, R.; Reynolds, R.; Ball, I.; Berry, R.; Johnson, K.; Mongia, H.

1983-01-01

The combustor performance submodels for complex flows are evaluated. The benchmark test cases for complex nonswirling flows are identified and analyzed. The introduction of swirl into the flow creates much faster mixing, caused by radial pressure gradients and increase in turbulence generation. These phenomena are more difficult to predict than the effects due to geometrical streamline curvatures, like the curved duct, and sudden expansion. Flow fields with swirl, both confined and unconfined are studied. The role of the dilution zone to achieve the turbine inlet radial profile plays an important part, therefore temperature field measurements were made in several idealized dilution zone configurations.

Exploring an interaction of adenosine A2A receptor variability with coffee and tea intake in Parkinson's disease.

PubMed

Tan, E K; Lu, Z Y; Fook-Chong, S M C; Tan, E; Shen, H; Chua, E; Yih, Y; Teo, Y Y; Zhao, Y

2006-09-05

Caffeine is an adenosine receptor A1 and A2A receptor antagonist and a putative functional genetic variant of the A2A receptor (2592C > Tins) mediates caffeine-induced anxiety. Here we investigated the potential interaction of this A2A genetic variant with the quantity of coffee and tea intake and their relationship with the risk of PD. A total of 441 subjects consisting of 222 PD and 219 race, gender and age matched controls were included. A multivariate analysis of the variables including the 2592C > Tins A2A genotypes, age of onset, gender, and the quantity of tea and coffee intake, interaction of the A2A genotypes with coffee intake, interaction of A2A genotypes with tea intake demonstrated the quantity of coffee intake to be significantly associated with PD (P < 0.0005, OR = 0.922, 95% CI: 0.881, 0.964). However, there was no significant interaction of the A2A genotypes with the quantity of coffee and tea intake in modulating the risk of PD. The dose dependent protective effect of coffee intake in PD was independent of the 2592C > Tins A2A genotype suggesting that the pharmacogenetic action of caffeine in PD may be mediated differently from other caffeine-induced neurologic syndromes.

Assessment of food intake input distributions for use in probabilistic exposure assessments of food additives.

PubMed

Gilsenan, M B; Lambe, J; Gibney, M J

2003-11-01

A key component of a food chemical exposure assessment using probabilistic analysis is the selection of the most appropriate input distribution to represent exposure variables. The study explored the type of parametric distribution that could be used to model variability in food consumption data likely to be included in a probabilistic exposure assessment of food additives. The goodness-of-fit of a range of continuous distributions to observed data of 22 food categories expressed as average daily intakes among consumers from the North-South Ireland Food Consumption Survey was assessed using the BestFit distribution fitting program. The lognormal distribution was most commonly accepted as a plausible parametric distribution to represent food consumption data when food intakes were expressed as absolute intakes (16/22 foods) and as intakes per kg body weight (18/22 foods). Results from goodness-of-fit tests were accompanied by lognormal probability plots for a number of food categories. The influence on food additive intake of using a lognormal distribution to model food consumption input data was assessed by comparing modelled intake estimates with observed intakes. Results from the present study advise some level of caution about the use of a lognormal distribution as a mode of input for food consumption data in probabilistic food additive exposure assessments and the results highlight the need for further research in this area.

Saturated Fat Intake Is Related to Heart Rate Variability in Women with Polycystic Ovary Syndrome.

PubMed

Graff, Scheila K; Mario, Fernanda M; Magalhães, Jose A; Moraes, Ruy S; Spritzer, Poli Mara

2017-01-01

There is a heightened risk for cardiovascular diseases in women with polycystic ovary syndrome (PCOS). Alterations in heart rate variability (HRV) may reflect subclinical cardiovascular disease, with a putative association between HRV and dietary fat. This study evaluated HRV in PCOS and control women based on the dietary intake of saturated fatty acid (SFA). Biochemical/hormonal profile, resting metabolic rate, physical activity, HRV in response to the Stroop test, and dietary intake were assessed in 84 PCOS and 54 control women stratified by median SFA intake in the PCOS group (8.5% of daily energy intake). Body mass index (p = 0.041), blood pressure (p < 0.01), and HOMA-IR (p = 0.003) were higher in PCOS vs. PCOS women had higher testosterone (p = 0.001), dehydroepiandrosterone sulfate (p = 0.012), and free androgen index (p = 0.001), and lower sex hormone-binding globulin levels than controls (p = 0.001). In both groups, the clinical profile and calorie intake were similar between SFA categories. In PCOS, testosterone was lower when SFA intake <8.5%. PCOS women with SFA <8.5% consumed more beans, fruits, and vegetables and had better frequency and time domain HRV indices. No differences in HRV were detected between SFA categories in controls. In PCOS, age and SFA intake were independent predictors of HRV. Lower SFA intake is related to improved cardiovascular autonomic function in PCOS. © 2017 S. Karger AG, Basel.

Tracking of dietary intake and factors associated with dietary change from early adolescence to adulthood: the ASH30 study.

PubMed

Lake, Amelia A; Adamson, Ashley J; Craigie, Angela M; Rugg-Gunn, Andrew J; Mathers, John C

2009-01-01

This paper describes the tracking of food intake from adolescence to adulthood according to location as an adult (at the time of the follow-up study) and gender. Additionally this paper explores factors associated with change in food intake. Two 3-day food diaries, demographic and socio-economic information were collected in 1980 and 2000 from the same 198 participants (81 male, 117 female). Foods consumed were assigned to the five categories in The Balance of Good Health (BGH) food model. The tracking of food intake was assessed using Pearson correlation analyses. In 2000 two questionnaires were completed. Demographic and key attributional factors, derived from closed and open-ended responses to the questionnaire, were compared with measured change using regression analysis. There was significant tracking of intake by food group from adolescence to adulthood according to location as an adult and gender. Eight combinations of descriptive variables and questionnaire factors were associated with change in intake of four of the five BGH food groups. Between adolescence and adulthood, dietary tracking is influenced by variables including gender and location. Attributions for change in food intake were associated with measured changes in food intake. In order to support healthier eating habits, it is important to be aware of factors contributing to changes in food intake, such as parental influences and perceived influences of time and work. Copyright 2009 S. Karger AG, Basel.

Weight indicators and nutrient intake in children and adolescents do not vary by sugar content in ready-to-eat cereal: results from National Health and Nutrition Examination Survey 2001-2006.

PubMed

Albertson, Ann M; Thompson, Douglas R; Franko, Debra L; Holschuh, Norton M

2011-03-01

Few studies have explored the relationship between sugar content in cereal and health outcome among children and adolescents. This study was designed to investigate the associations between ready-to-eat cereals, categorized by sugar content, with weight indicators and nutrient intake profiles. Data collected from 6- to 18-year-old US children and adolescents (N = 9660) in the National Health and Nutrition Examination Survey 2001-06 were used to analyze cereal consumption. Body mass index (BMI), BMI-for-age, waist-to-height ratio, percent overweight or obese, mean day-1 intake, and usual daily intake of macronutrients and micronutrients were the dependent variables; day-1 cereal intake, categorized by tertiles of sugar content, was the main independent variable. Weighted regression with adjustment for the survey design was used to model the dependent variables as a function of day-1 cereal intake, adjusting for age group, sex, race/ethnicity, total day-1 intake of energy, calcium and sugar, the Healthy Eating Index-2005 total score, and household income. For all tertiles of sugar classifications of cereal, children who consumed cereal had significantly lower BMI compared with children who consumed no cereal (P's < .05). Similarly, when compared with children who consumed no cereal, those who ate cereal consumed significantly less fat and cholesterol and significantly more carbohydrates, sugar, whole grains, vitamin A, thiamin, riboflavin, niacin, vitamin B(6), folic acid, vitamin B(12), vitamin C, calcium, magnesium, iron, and zinc. Lower weight and positive nutrient profiles were associated with cereal consumption regardless of sugar content. Copyright © 2011 Elsevier Inc. All rights reserved.

Is the relationship between sedentary behaviour and cardiometabolic health in adolescents independent of dietary intake? A systematic review.

PubMed

Fletcher, E; Leech, R; McNaughton, S A; Dunstan, D W; Lacy, K E; Salmon, J

2015-09-01

Screen time, but not overall sedentary behaviour, is consistently related to cardiometabolic health in adolescents. Because of the associations screen time has with dietary intake, diet may be an important factor in the screen time and health relationship; however, evidence has not previously been synthesized. Thus, the aim of this systematic review was to explore whether the associations between various sedentary behaviours and cardiometabolic risk markers are independent of dietary intake in adolescents. Online databases and personal libraries were searched for peer-reviewed original research articles published in English before March 2014. Included studies assessed associations between sedentary behaviour and cardiometabolic markers in 12- to 18-year-olds and adjusted for dietary intake. Twenty-five studies met the inclusion criteria. From the 21 studies examining sedentary behaviour and adiposity, the majority found significant positive associations between television viewing, screen time and self-reported overall sedentary behaviour with markers of adiposity, independent of dietary intake. No significant associations between screen time with blood pressure and cholesterol were reported. Sedentary behaviour appears to be associated with adiposity in adolescents, irrespective of dietary intake. However, the variability of dietary variables between studies suggests further work is needed to understand the role of dietary intake when examining these associations in youth. © 2015 World Obesity.

RELATIONS BETWEEN DAIRY FOOD INTAKE AND ARTERIAL STIFFNESS: PULSE WAVE VELOCITY AND PULSE PRESSURE

PubMed Central

Crichton, Georgina E.; Elias, Merrrill F.; Dore, Gregory A.; Abhayaratna, Walter P.; Robbins, Michael A.

2012-01-01

Modifiable risk factors, such as diet, are becomingly increasingly important in the management of cardiovascular disease, one of the greatest major causes of death and disease burden. Few studies have examined the role of diet as a possible means of reducing arterial stiffness, as measured by pulse wave velocity, an independent predictor of cardiovascular events and all-cause mortality. The aim of this study was to investigate whether dairy food intake is associated with measures of arterial stiffness including carotid-femoral pulse wave velocity and pulse pressure. A cross-sectional analysis of a subset of the Maine Syracuse Longitudinal Study sample was performed. A linear decrease in pulse wave velocity was observed across increasing intakes of dairy food consumption (ranging from never/rarely to daily dairy food intake). The negative linear relationship between pulse wave velocity and intake of dairy food was independent of demographic variables, other cardiovascular disease risk factors and nutrition variables. The pattern of results was very similar for pulse pressure, while no association between dairy food intake and lipid levels was found. Further intervention studies are needed to ascertain whether dairy food intake may be an appropriate dietary intervention for the attenuation of age-related arterial stiffening and reduction of cardiovascular disease risk. PMID:22431583

Development and application of a standardized flow measurement uncertainty analysis framework to various low-head short-converging intake types across the United States federal hydropower fleet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Brennan T

2015-01-01

Turbine discharges at low-head short converging intakes are difficult to measure accurately. The proximity of the measurement section to the intake entrance admits large uncertainties related to asymmetry of the velocity profile, swirl, and turbulence. Existing turbine performance codes [10, 24] do not address this special case and published literature is largely silent on rigorous evaluation of uncertainties associated with this measurement context. The American Society of Mechanical Engineers (ASME) Committee investigated the use of Acoustic transit time (ATT), Acoustic scintillation (AS), and Current meter (CM) in a short converging intake at the Kootenay Canal Generating Station in 2009. Basedmore » on their findings, a standardized uncertainty analysis (UA) framework for velocity-area method (specifically for CM measurements) is presented in this paper given the fact that CM is still the most fundamental and common type of measurement system. Typical sources of systematic and random errors associated with CM measurements are investigated, and the major sources of uncertainties associated with turbulence and velocity fluctuations, numerical velocity integration technique (bi-cubic spline), and the number and placement of current meters are being considered for an evaluation. Since the velocity measurements in a short converging intake are associated with complex nonlinear and time varying uncertainties (e.g., Reynolds stress in fluid dynamics), simply applying the law of propagation of uncertainty is known to overestimate the measurement variance while the Monte Carlo method does not. Therefore, a pseudo-Monte Carlo simulation method (random flow generation technique [8]) which was initially developed for the purpose of establishing upstream or initial conditions in the Large-Eddy Simulation (LES) and the Direct Numerical Simulation (DNS) is used to statistically determine uncertainties associated with turbulence and velocity fluctuations. This technique is then combined with a bi-cubic spline interpolation method which converts point velocities into a continuous velocity distribution over the measurement domain. Subsequently the number and placement of current meters are simulated to investigate the accuracy of the estimated flow rates using the numerical velocity-area integration method outlined in ISO 3354 [12]. The authors herein consider that statistics on generated flow rates processed with bi-cubic interpolation and sensor simulations are the combined uncertainties which already accounted for the effects of all those three uncertainty sources. A preliminary analysis based on the current meter data obtained through an upgrade acceptance test of a single unit located in a mainstem plant has been presented.« less

Energy balance related behaviour: personal, home- and friend-related factors among schoolchildren in Europe studied in the ENERGY-project.

PubMed

te Velde, Saskia J; Singh, Amika; Chinapaw, Mai; De Bourdeaudhuij, Ilse; Jan, Natasa; Kovacs, Eva; Bere, Elling; Vik, Froydis N; Bringolf-Isler, Bettina; Manios, Yannis; Moreno, Luis; Brug, Johannes

2014-01-01

To design interventions that target energy balance-related behaviours, knowledge of primary schoolchildren's perceptions regarding soft drink intake, fruit juice intake, breakfast consumption, TV viewing and physical activity (PA) is essential. The current study describes personal beliefs and attitudes, home- and friend-related variables regarding these behaviours across Europe. Cross-sectional study in which personal, family and friend -related variables were assessed by validated questionnaires, and dichotomized as favourable versus unfavourable answers. Logistic regression analyses were conducted to estimate proportions of children giving unfavourable answers and test between-country differences. A survey in eight European countries. A total of 7903 10-12 year old primary schoolchildren. A majority of the children reported unfavourable attitudes, preferences and subjective norms regarding soft drink, fruit juice intake and TV viewing accompanied with high availability and accessibility at home. Few children reported unfavourable attitudes and preferences regarding breakfast consumption and PA. Many children reported unfavourable health beliefs regarding breakfast consumption and TV viewing. Substantial differences between countries were observed, especially for variables regarding soft drink intake, breakfast consumption and TV viewing. The surveyed children demonstrated favourable attitudes to some healthy behaviours (PA, breakfast intake) as well as to some unhealthy behaviours (soft drink consumption, TV viewing). Additionally, many children across Europe have personal beliefs and are exposed to social environments that are not supportive to engagement in healthy behaviours. Moreover, the large differences in personal, family and friend-related variables across Europe argue for implementing different strategies in the different European countries.

The Influence of Swirl Brakes and a Tip Discharge Orifice on the Rotordynamic Forces Generated by Discharge-to-Suction Leakage Flows in Shrouded Centrifugal Pumps

NASA Technical Reports Server (NTRS)

Sivo, Joseph M.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

1993-01-01

Recent experiments conducted in the Rotor Force Test Facility at the California Institute of Technology have examined the effects of a tip leakage restriction and swirl brakes on the rotordynamic forces due to leakage flows on an impeller undergoing a prescribed circular whirl. The experiments simulate the leakage flow conditions and geometry of the Alternate Turbopump Design (ATD) of the Space Shuttle High Pressure Oxygen Turbopump and are critical to evaluating the pump's rotordynamic instability problems. Previous experimental and analytical results have shown that discharge-to-suction leakage flows in the annulus of a shrouded centrifugal pump contribute substantially to the fluid induced rotordynamic forces. Also, previous experiments have shown that leakage inlet (pump discharge) swirl can increase the cross-coupled stiffness coefficient and hence increase the range of positive whirl for which the tangential force is destabilizing. In recent experimental work, the present authors demonstrated that when the swirl velocity within the leakage path is reduced by the introduction of ribs or swirl brakes, then a substantial decrease in both the destabilizing normal and tangential forces could be achieved. Motivation for the present research is that previous experiments have shown that restrictions such as wear rings or orifices at pump inlets affect the leakage forces. Recent pump designs such as the Space Shuttle Alternate Turbopump Design (ATD) utilize tip orifices at discharge for the purpose of establishing axial thrust balance. The ATD has experienced rotordynamic instability problems and one may surmise that these tip discharge orifices may also have an important effect on the normal and tangential forces in the plane of impeller rotation. The present study determines if such tip leakage restrictions contribute to undesirable rotordynamic forces. Additional motivation for the present study is that the widening of the leakage path annular clearance and the installation of swirl brakes in the ATD has been proposed to solve its instability problems. The present study assesses the effect of such a design modification on the rotordynamic forces. The experimental apparatus consists of a solid or dummy impeller, a housing instrumented for pressure measurements, a rotating dynamometer and an eccentric whirl mechanism. The solid impeller is used so that leakage flow contributions to the forces are measured, but the main throughflow contributions are not experienced. The inner surface of the housing has been modified to accommodate meridional ribs or swirl brakes within the leakage annulus. In addition, the housing has been modified to accommodate a discharge orifice that qualitatively simulates one side of the balance piston orifice of the Space Shuttle ATD. Results indicate the detrimental effects of a discharge orifice and the beneficial effects of brakes. Plots of the tangential and normal forces versus whirl ratio show a substantial increase in these forces along with destabilizing resonances at some positive whirl ratios when a discharge orifice is added. When brakes are added, some of the detrimental effects of the orifice are reduced. For the tangential force, a plot versus whirl ratio shows a significant reduction and a destabilizing resonance appears to be eliminated. For the normal force, although the overall force is not reduced, again a destabilizing resonance appears to be eliminated.

On the size and distribution of rings and coherent vortices in the Sargasso Sea

NASA Astrophysics Data System (ADS)

Luce, David L.; Rossby, Tom

2008-05-01

The container motor vessel CMV Oleander, which operates between New Jersey and Bermuda, crosses the Gulf Stream and Sargasso Sea all year round on a semiweekly schedule. Using an acoustic Doppler current profiler, measurements of upper ocean currents have been made on a regular basis since the fall of 1992. In this paper we examine the database for evidence of axisymmetric coherent vortices including the distribution and intensity of cold core rings. To detect the existence of coherent vortices, the patterns of current vectors averaged between 40 and 80 m depth were fit to an axisymmetric Gaussian vortex model. The parameters of the model were axis location, maximum tangential, or swirl, speed, and radius at which the maximum swirl was measured. We were able to distinguish between the well-known cold core "rings" (CCRs) pinched from the Gulf Stream, and a population of cyclonic and anticyclonic "vortices" in the Sargasso Sea. Both the rings and the Sargasso Sea vortices showed radii of 64 ± 18 km, albeit with different swirl speeds. The rings, close to the Gulf Stream, exhibited a typical maximum swirl speed of 0.98 ± 0.40 m s-1 and a center relative vorticity of 0.64 ± 0.35 × 10-4 s-1, almost 80% of the planetary vorticity for the region. The more uniform population of Sargasso Sea vortices contained approximately equal numbers of cyclones and anticyclones, with mean speeds of +0.43 and -0.55 m s-1, and center relative vorticities of +0.24 × 10-4 s-1 and -0.29 × 10-4 s-1, respectively.

Evaluation of Oral Anticoagulant-Associated Intracranial Parenchymal Hematomas Using CT Findings.

PubMed

Gökçe, E; Beyhan, M; Acu, B

2015-06-01

Intracranial hemorrhage (ICH) is one of the most serious and lethal complications of anticoagulants with a reported incidence of 5-18.5 %. Computed tomographic (CT) findings, should be carefully studied because early diagnosis and treatment of oral anticoagulant use-associated hematomas are vitally important. In the present study, CT findings of intraparenchymal hematomas associated with anticoagulant and antihypertensive use are presented. This study included 45 patients (25 men, 20 women) under anticoagulant (21 patients) or antihypertensive (24 patients) treatment who had brain CT examinations due to complaints and findings suggesting cerebrovascular disease during July 2010-October 2013 period. CT examinations were performed to determine hematoma volumes and presence of swirl sign, hematocrit effect, mid-line shift effect, and intraventricular extension. The patients were 40-89 years of age. In four cases, a total of 51 intraparenchymal hematomas (42 cerebral, 7 cerebellar and 2 brain stem) were detected in multiple foci. Hematoma volumes varied from 0.09 to 284.00 ml. Swirl sign was observed in 87.5 and 63.0 % of OAC-associated ICHs and non-OAC-associated ICHs, respectively. In addition, hematocrit effect was observed in 41.6 % of OAC-associated and in 3.7 % of non-OAC-associated ICHs. Volume increases were observed in all 19 hematomas where swirl sign was detected, and follow-up CT scanning was conducted. Mortality of OAC-associated ICHs was correlated with initial volumes of hematoma, mid-line shift amount, and intraventricular extension. Detection of hematocrit effect by CT scanning of intracranial hematomas should be cautionary in oral anticoagulant use, while detection of swirl sign should be suggestive of active hemorrhage.

Effects of injection parameters, boost, and swirl ratio on gasoline compression ignition operation at idle and low-load conditions

DOE PAGES

Kodavasal, Janardhan; Kolodziej, Christopher P.; Ciatti, Stephen A.; ...

2016-11-03

In this study, we study the effects of injector nozzle inclusion angle, injection pressure, boost, and swirl ratio on gasoline compression ignition combustion. Closed-cycle computational fluid dynamics simulations using a 1/7th sector mesh representing a single cylinder of a four-cylinder 1.9 L diesel engine, operated in gasoline compression ignition mode with 87 anti-knock index (AKI) gasoline, were performed. Two different operating conditions were studied—the first is representative of idle operation (4 mg fuel/cylinder/cycle, 850 r/min), and the second is representative of a low-load condition (10 mg fuel/cylinder/cycle, 1500 r/min). The mixture preparation and reaction space from the simulations were analyzedmore » to gain insights into the effects of injection pressure, nozzle inclusion angle, boost, and swirl ratio on achieving stable low-load to idle gasoline compression ignition operation. It was found that narrower nozzle inclusion angles allow for more reactivity or propensity to ignition (determined qualitatively by computing constant volume ignition delays) and are suitable over a wider range of injection timings. Under idle conditions, it was found that lower injection pressures helped to reduce overmixing of the fuel, resulting in greater reactivity and ignitability (ease with which ignition can be achieved) of the gasoline. However, under the low-load condition, lower injection pressures did not increase ignitability, and it is hypothesized that this is because of reduced chemical residence time resulting from longer injection durations. Reduced swirl was found to maintain higher in-cylinder temperatures through compression, resulting in better ignitability. It was found that boosting the charge also helped to increase reactivity and advanced ignition timing.« less

Effects of injection parameters, boost, and swirl ratio on gasoline compression ignition operation at idle and low-load conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kodavasal, Janardhan; Kolodziej, Christopher P.; Ciatti, Stephen A.

In this study, we study the effects of injector nozzle inclusion angle, injection pressure, boost, and swirl ratio on gasoline compression ignition combustion. Closed-cycle computational fluid dynamics simulations using a 1/7th sector mesh representing a single cylinder of a four-cylinder 1.9 L diesel engine, operated in gasoline compression ignition mode with 87 anti-knock index (AKI) gasoline, were performed. Two different operating conditions were studied—the first is representative of idle operation (4 mg fuel/cylinder/cycle, 850 r/min), and the second is representative of a low-load condition (10 mg fuel/cylinder/cycle, 1500 r/min). The mixture preparation and reaction space from the simulations were analyzedmore » to gain insights into the effects of injection pressure, nozzle inclusion angle, boost, and swirl ratio on achieving stable low-load to idle gasoline compression ignition operation. It was found that narrower nozzle inclusion angles allow for more reactivity or propensity to ignition (determined qualitatively by computing constant volume ignition delays) and are suitable over a wider range of injection timings. Under idle conditions, it was found that lower injection pressures helped to reduce overmixing of the fuel, resulting in greater reactivity and ignitability (ease with which ignition can be achieved) of the gasoline. However, under the low-load condition, lower injection pressures did not increase ignitability, and it is hypothesized that this is because of reduced chemical residence time resulting from longer injection durations. Reduced swirl was found to maintain higher in-cylinder temperatures through compression, resulting in better ignitability. It was found that boosting the charge also helped to increase reactivity and advanced ignition timing.« less

Numerical Research of Nitrogen Oxides Formation for Justification of Modernization of P-49 Nazarovsky State District Power Plant Boiler on the Low-temperature Swirl Technology of Burning

NASA Astrophysics Data System (ADS)

Trinchenko, A. A.; Paramonov, A. P.; Skouditskiy, V. E.; Anoshin, R. G.

2017-11-01

Compliance with increasingly stringent normative requirements to the level of pollutants emissions when using organic fuel in the energy sector as a main source of heat, demands constant improvement of the boiler and furnace equipment and the power equipment in general. The requirements of the current legislation in the field of environmental protection prescribe compliance with established emission standards for both new construction and the improvement of energy equipment. The paper presents the results of numerical research of low-temperature swirl burning in P-49 Nazarovsky state district power plant boiler. On the basis of modern approaches of the diffusion and kinetic theory of burning and the analysis physical and chemical processes of a fuel chemically connected energy transition in thermal, generation and transformation of gas pollutants, the technological method of nitrogen oxides decomposition on the surface of carbon particles with the formation of environmentally friendly carbonic acid and molecular nitrogen is considered during the work of low-temperature swirl furnace. With the use of the developed model, methodology and computer program, variant calculations of the combustion process were carried out and a quantitative estimate of the emission level of the nitrogen oxides of the boiler being modernized. The simulation results the and the experimental data obtained during the commissioning and balance tests of the P-49 boiler with a new furnace are confirmed that the organization of swirl combustion has allowed to increase the efficiency of work, to reduce slagging, to significantly reduce nitrogen oxide emissions, to improve ignition and burnout of fuel.

Engine with exhaust gas recirculation system and variable geometry turbocharger

DOEpatents

Keating, Edward J.

2015-11-03

An engine assembly includes an intake assembly, an internal combustion engine defining a plurality of cylinders and configured to combust a fuel and produce exhaust gas, and an exhaust assembly in fluid communication with a first subset of the plurality of cylinders. Each of the plurality of cylinders are provided in fluid communication with the intake assembly. The exhaust assembly is provided in fluid communication with a first subset of the plurality of cylinders, and a dedicated exhaust gas recirculation system in fluid communication with both a second subset of the plurality of cylinders and with the intake assembly. The dedicated exhaust gas recirculation system is configured to route all of the exhaust gas from the second subset of the plurality of cylinders to the intake assembly. Finally, the engine assembly includes a turbocharger having a variable geometry turbine in fluid communication with the exhaust assembly.

The development of a model to predict BW gain of growing cattle fed grass silage-based diets.

PubMed

Huuskonen, A; Huhtanen, P

2015-08-01

The objective of this meta-analysis was to develop and validate empirical equations predicting BW gain (BWG) and carcass traits of growing cattle from intake and diet composition variables. The modelling was based on treatment mean data from feeding trials in growing cattle, in which the nutrient supply was manipulated by wide ranges of forage and concentrate factors. The final dataset comprised 527 diets in 116 studies. The diets were mainly based on grass silage or grass silage partly or completely replaced by whole-crop silages, hay or straw. The concentrate feeds consisted of cereal grains, fibrous by-products and protein supplements. Mixed model regression analysis with a random study effect was used to develop prediction equations for BWG and carcass traits. The best-fit models included linear and quadratic effects of metabolisable energy (ME) intake per metabolic BW (BW0.75), linear effects of BW0.75, and dietary concentrations of NDF, fat and feed metabolisable protein (MP) as significant variables. Although diet variables had significant effects on BWG, their contribution to improve the model predictions compared with ME intake models was small. Feed MP rather than total MP was included in the final model, since it is less correlated to dietary ME concentration than total MP. None of the quadratic terms of feed variables was significant (P>0.10) when included in the final models. Further, additional feed variables (e.g. silage fermentation products, forage digestibility) did not have significant effects on BWG. For carcass traits, increased ME intake (ME/BW0.75) improved both dressing proportion (P0.10) effect on dressing proportion or carcass conformation score, but it increased (P<0.01) carcass fat score. The current study demonstrated that ME intake per BW0.75 was clearly the most important variable explaining the BWG response in growing cattle. The effect of increased ME supply displayed diminishing responses that could be associated with increased energy concentration of BWG, reduced diet metabolisability (proportion of ME of gross energy) and/or decreased efficiency of ME utilisation for growth with increased intake. Negative effects of increased dietary NDF concentration on BWG were smaller compared to responses that energy evaluation systems predict for energy retention. The present results showed only marginal effects of protein supply on BWG in growing cattle.

Family-related predictors of body weight and weight-related behaviours among children and adolescents: a systematic umbrella review.

PubMed

Cislak, A; Safron, M; Pratt, M; Gaspar, T; Luszczynska, A

2012-05-01

This umbrella review analysed the relationships between family variables and child/adolescent body weight, diet and physical activity. In line with theories of health behaviour change, it was assumed that behaviour-specific family variables (i.e. beliefs, perceptions and practices referring to food intake or physical activity) would have stronger support than more general family variables (i.e. socio-economic status or general parental practices). Data obtained from 18 systematic reviews (examining 375 quantitative studies) were analysed. Reviews of experimental trials generally supported the effectiveness of reward/positive reinforcement parental strategies, parental involvement in treatment or prevention programmes, and cognitive-behavioural treatment in reducing child/adolescent body mass and/or obesity. Results across reviews of correlational studies indicated that healthy nutrition of children/adolescents was related to only one parental practice (parental monitoring), but was associated with several behaviour-specific family variables (e.g. a lack of restrictive control over food choices, high intake of healthy foods and low intake of unhealthy foods by parents and siblings, low pressure to consume foods). With regard to adolescent physical activity, stronger support was also found for behaviour-specific variables (e.g. physical activity of siblings), and for certain socio-economic variables (e.g. parental education). Child and adolescent obesity prevention programmes should account for behaviour-specific family variables. © 2011 Blackwell Publishing Ltd.

Identification of biological traits associated with differences in residual energy intake among lactating Holstein cows.

PubMed

Fischer, A; Delagarde, R; Faverdin, P

2018-05-01

Residual feed intake, which is usually used to estimate individual variation of feed efficiency, requires frequent and accurate measurements of individual feed intake to be carried out. Developing a breeding scheme based on residual feed intake in dairy cows is therefore complicated, especially because feed intake is not measurable for a large population. Another solution could be to focus on biological determinants of feed efficiency, which could potentially be directly and broadband measurable on farm. Several phenotypes have been identified in literature as being associated with differences in feed efficiency. The present study therefore aims to identify which biological mechanisms are associated with residual energy intake (REI) differences among dairy cows. Several candidate phenotypes were recorded frequently and simultaneously throughout the first 238 d in milk for 60 Holstein cows fed on a constant diet based on maize silage. A multiple linear regression of the 238 d in milk average of net energy intake was fitted on the 238 d in milk averages for milk energy output, metabolic body weight, the sum over the 238 d in milk of both, body condition score loss and gain, and the residuals were defined as REI. A partial least square regression was fitted over all biological traits to explain REI variability. Linear multiple regression explained 93.6% of net energy intake phenotypic variation, with 65.5% associated with lactation requirement, 23.2% with maintenance, and 4.9% with body reserves change; the 6.4% residuals represented REI. Overall, measured biological traits contributed to 58.9% of REI phenotypic variability, which were mainly explained by activity (26.5%) and feeding behavior (21.3%). However, apparent confounding was observed between behavior, activity, digestibility, and rumen-temperature variables. Drawing a conclusion on biological traits that explain feed efficiency differences among dairy cows was not possible due to this apparent confounding between the measured variables. Further investigation is needed to validate these results and to characterize the causal relationship of feed efficiency with feeding behavior, digestibility, body reserves change, activity, and rumen temperature. The Authors. Published by FASS Inc. and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

Influence of nanosecond repetitively pulsed discharges on the stability of a swirled propane/air burner representative of an aeronautical combustor

PubMed Central

Barbosa, S.; Pilla, G.; Lacoste, D. A.; Scouflaire, P.; Ducruix, S.; Laux, C. O.; Veynante, D.

2015-01-01

This paper reports on an experimental study of the influence of a nanosecond repetitively pulsed spark discharge on the stability domain of a propane/air flame. This flame is produced in a lean premixed swirled combustor representative of an aeronautical combustion chamber. The lean extinction limits of the flame produced without and with plasma are determined and compared. It appears that only a low mean discharge power is necessary to increase the flame stability domain. Lastly, the effects of several parameters (pulse repetition frequency, global flowrate, electrode location) are studied. PMID:26170424

The swirl turbine

NASA Astrophysics Data System (ADS)

Haluza, M.; Pochylý, F.; Rudolf, P.

2012-11-01

In the article is introduced the new type of the turbine - swirl turbine. This turbine is based on opposite principle than Kaplan turbine. Euler equation is satisfied in the form gHηh = -u2vu2. From this equation is seen, that inflow of liquid into the runner is without rotation and on the outflow is a rotation of liquid opposite of rotation of runner. This turbine is suitable for small head and large discharge. Some constructional variants of this turbine are introduced in the article and theoretical aspects regarding losses in the draft tube. The theory is followed by computational simulations in Fluent and experiments using laser Doppler anemometry.

Finite-difference solution for turbulent swirling compressible flow in axisymmetric ducts with struts

NASA Technical Reports Server (NTRS)

Anderson, O. L.

1974-01-01

A finite-difference procedure for computing the turbulent, swirling, compressible flow in axisymmetric ducts is described. Arbitrary distributions of heat and mass transfer at the boundaries can be treated, and the effects of struts, inlet guide vanes, and flow straightening vanes can be calculated. The calculation procedure is programmed in FORTRAN 4 and has operated successfully on the UNIVAC 1108, IBM 360, and CDC 6600 computers. The analysis which forms the basis of the procedure, a detailed description of the computer program, and the input/output formats are presented. The results of sample calculations performed with the computer program are compared with experimental data.

Turbomachinery Laboratory Texas A and M University research progress on annular gas seals

NASA Technical Reports Server (NTRS)

Childs, Dara W.

1994-01-01

Three helically-grooved seals were tested and the results were compared to the MTI code SPIRALG. A smooth annular seal was tested at six eccentricity ratios from 0 to 0.5. The following are concluded in this viewgraph presentation: (1) Helical-grooved seals provide a substantial reduction in cross-coupled stiffness coefficients. Negative k(sub xy) values are obtained for no-swirl or low-swirl cases. (2) SPIRALG is completely unsuitable for the type of seal tested, namely, turbulent flow, wide grooves and lands, etc. (3) A good analysis code is needed to guide the design of helically-grooved annular seals including groove and smooth sections.

Predicting dietary intakes with simple food recall information: a case study from rural Mozambique.

PubMed

Rose, D; Tschirley, D

2003-10-01

Improving dietary status is an important development objective, but monitoring of progress in this area can be too costly for many low-income countries. This paper demonstrates a simple, inexpensive technique for monitoring household diets in Mozambique. Secondary analysis of data from an intensive field survey on household food consumption and agricultural practices, known as the Nampula/Cabo Delgado Study (NCD). In total, 388 households in 16 villages from a stratified random sample of rural areas in Nampula and Cabo Delgado provinces in northern Mozambique. The NCD employed a quantitative 24-h food recall on two nonconsecutive days in each of the three different seasons. A dietary intake prediction model was developed with linear regression techniques based on NCD nutrient intake data and easy-to-collect variables, such as food group consumption and household size The model was used to predict the prevalence of low intakes among subsamples from the field study using only easy-to-collect variables. Using empirical data for the harvest season from the original NCD study, 40% of the observations on households had low-energy intakes, whereas rates of low intake for protein, vitamin A, and iron, were 14, 94, and 39, respectively. The model developed here predicted that 42% would have low-energy intakes and that 12, 93, and 35% would have low-protein, vitamin A, and iron intakes, respectively. Similarly, close predictions were found using an aggregate index of overall diet quality. This work demonstrates the potential for using low-cost methods for monitoring dietary intake in Mozambique.

Dietary L-Arginine Intakes and the Risk of Metabolic Syndrome: A 6-Year Follow-Up in Tehran Lipid and Glucose Study.

PubMed

Mirmiran, Parvin; Moghadam, Sajjad Khalili; Bahadoran, Zahra; Ghasemi, Asghar; Azizi, Fereidoun

2017-12-01

This study was conducted to investigate whether regular dietary intake of L-arginine could affect the occurrence of metabolic syndrome (MetS). Eligible adult men and women (n=1,237), who participated in the Tehran Lipid and Glucose Study, were followed for a median of 6.3 years. Dietary intakes of L-arginine and serum nitrate and nitrite (NOx) concentration were assessed at baseline (2006~2008), and demographics, anthropometrics, and biochemical variables were evaluated at baseline and follow-up examinations. The occurrence of MetS was assessed in relation to total L-arginine, intakes of L-arginine from animal and plant sources, with adjustment of potential confounding variables. Participants who had higher intake of L-arginine also had higher serum NOx at baseline (35.0 vs. 30.5 μmol/L, P <0.05). After 6 years of follow-up, higher intakes of L-arginine from animal sources were accompanied with increased risk of MetS [odd ratios (OR)=1.49, 95% confidence interval (95% CI)=1.02~2.18]. Compared to the lowest, the highest intakes of L-arginine from plant sources were related to significantly reduced risk of MetS (OR=0.58, 95% CI=0.32~0.99). In conclusion, our findings suggest a potentially protective effect of plant derived L-arginine intakes against development of MetS and its phenotypes; moreover, higher intakes of L-arginine from animal sources could be a dietary risk factor for development of metabolic disorders.

Single element injector cold flow testing for STME swirl coaxial injector element design

NASA Technical Reports Server (NTRS)

Hulka, J.; Schneider, J. A.

1993-01-01

An oxidizer-swirled coaxial element injector is being investigated for application in the Space Transportation Main Engine (STME). Single element cold flow experiments were conducted to provide characterization of the STME injector element for future analysis, design, and optimization. All tests were conducted to quiescent, ambient backpressure conditions. Spray angle, circumferential spray uniformity, dropsize, and dropsize distribution were measured in water-only and water/nitrogen flows. Rupe mixing efficiency was measured using water/sucrose solution flows with a large grid patternator for simple comparative evaluation of mixing. Factorial designs of experiment were used for statistical evaluation of injector geometrical design features and propellant flow conditions on mixing and atomization. Increasing the free swirl angle of the liquid oxidizer had the greatest influence on increasing the mixing efficiency. The addition of gas assistance had the most significant effect on reducing oxidizer droplet size parameters and increasing droplet size distribution. Increasing the oxidizer injection velocity had the greatest influence for reducing oxidizer droplet size parameters and increasing size distribution for non-gas assisted flows. Single element and multi-element subscale hot fire testing are recommended to verify optimized designs before committing to the STME design.

Measurements of the Early Development of Trailing Vorticity from a Rotor

NASA Technical Reports Server (NTRS)

McAlister, Kenneth W.; Heineck, James T.

2002-01-01

The wake behind a two-bladed model rotor in light climb was measured using particle image velocimetry, with particular emphasis on the development of the trailing vortex during the first revolution of the rotor. The distribution of vorticity was distinguished from the slightly elliptical swirl pattern. Peculiar dynamics within the "void" region may explain why the peak vorticity appeared to shift away from the center as the vortex aged, suggesting the onset of instability. The swirl and axial velocities (which reached 44% and 12% of the rotor tip speed, respectively) were found to be asymmetric relative to the vortex center. In particular, the axial flow was composed of two concentrated zones moving in opposite directions. The radial distribution of the circulation rapidly increased in magnitude until reaching a point just beyond the core radius, after which the rate of growth decreased significantly. The core-radius circulation increased slightly with wake age, but the large-radius circulation appeared to remain relatively constant. The radial distributions of swirl velocity and vorticity exhibit self-similar behaviors, especially within the core. The diameter of the vortex core was initially about 10% of the rotor-blade chord, but more than doubled its size after one revolution of the rotor.

Effects of Wall-Normal and Angular Momentum Injections in Airfoil Separation Control

NASA Astrophysics Data System (ADS)

Munday, Phillip M.; Taira, Kunihiko

2018-05-01

The objective of this computational study is to quantify the influence of wall-normal and angular momentum injections in suppressing laminar flow separation over a canonical airfoil. Open-loop control of fully separated, incompressible flow over a NACA 0012 airfoil at $\\alpha = 9^\\circ$ and $Re = 23,000$ is examined with large-eddy simulations. This study independently introduces wall-normal momentum and angular momentum into the separated flow using swirling jets through model boundary conditions. The response of the flow field and the surface vorticity fluxes to various combinations of actuation inputs are examined in detail. It is observed that the addition of angular momentum input to wall-normal momentum injection enhances the suppression of flow separation. Lift enhancement and suppression of separation with the wall-normal and angular momentum inputs are characterized by modifying the standard definition of the coefficient of momentum. The effect of angular momentum is incorporated into the modified coefficient of momentum by introducing a characteristic swirling jet velocity based on the non-dimensional swirl number. With this single modified coefficient of momentum, we are able to categorize each controlled flow into separated, transitional, and attached flows.

Numerical simulation of hydrodynamic flows in the jet electric

NASA Astrophysics Data System (ADS)

Sarychev, V. D.; Granovskii, A. Yu; Nevskii, S. A.

2016-02-01

On the basis of concepts from magnetic hydrodynamics the mathematical model of hydrodynamic flows in the stream of electric arc plasma, obtained between the rod electrode and the target located perpendicular to the flat conductive, was developed. The same phenomenon occurs in the welding arc, arc plasma and other injection sources of charged particles. The model is based on the equations of magnetic hydrodynamics with special boundary conditions. The obtained system of equations was solved by the numerical method of finite elements with an automatic selection of the time step. Calculations were carried out with regard to the normal plasma inleakage on the solid conducting surface and the surface with the orifice. It was found that the solid surface facilitates three swirling zones. Interaction of these zones leads to the formation of two stable swirling zones, one of which is located at a distance of two radii from the axis and midway between the electrodes, another is located in the immediate vicinity of the continuous electrode. In this zone plasma backflow scattering fine particles is created. Swirling zones are not formed by using the plane electrode with an orifice. Thus, the fine particles can pass through it and consolidate.

Experimental and Numerical Research of a Novel Combustion Chamber for Small Gas Turbine Engines

NASA Astrophysics Data System (ADS)

Tuma, J.; Kubata, J.; Betak, V.; Hybl, R.

2013-04-01

New combustion chamber concept (based on burner JETIS-JET Induced Swirl) for small gas turbine engine (up to 200kW) is presented in this article. The combustion chamber concept is based on the flame stabilization by the generated swirl swirl generated by two opposite tangentially arranged jet tubes in the intermediate zone, this arrangement replaces air swirler, which is very complicated and expensive part in the scope of small gas turbines with annular combustion chamber. The mixing primary jets are oriented partially opposite to the main exhaust gasses flow, this enhances hot product recirculation and fuel-air mixing necessary for low NOx production and flame stability. To evaluate the designed concept a JETIS burner demonstrator (methane fuel) was manufactured and atmospheric experimental measurements of CO, NOx for various fuel nozzles and jet tubes the configuration were done. Results of these experiments and comparison with CFD simulation are presented here. Practical application of the new chamber concept in small gas turbine liquid fuel combustor was evaluated (verified) on 3 nozzles planar combustor sector test rig at atmospheric conditions results of the experiment and numerical simulation are also presented.

Numerical Assessment of Novel Helical/Spiral Grafts with Improved Hemodynamics for Distal Graft Anastomoses

PubMed Central

Kabinejadian, Foad; McElroy, Michael; Ruiz-Soler, Andres; Leo, Hwa Liang; Slevin, Mark A.; Badimon, Lina

2016-01-01

In the present work, numerical simulations were conducted for a typical end-to-side distal graft anastomosis to assess the effects of inducing secondary flow, which is believed to remove unfavourable flow environment. Simulations were carried out for four models, generated based on two main features of 'out-of-plane helicity' and 'spiral ridge' in the grafts as well as their combination. Following a qualitative comparison against in vitro data, various mean flow and hemodynamic parameters were compared and the results showed that helicity is significantly more effective in inducing swirling flow in comparison to a spiral ridge, while their combination could be even more effective. In addition, the induced swirling flow was generally found to be increasing the wall shear stress and reducing the flow stagnation and particle residence time within the anastomotic region and the host artery, which may be beneficial to the graft longevity and patency rates. Finally, a parametric study on the spiral ridge geometrical features was conducted, which showed that the ridge height and the number of spiral ridges have significant effects on inducing swirling flow, and revealed the potential of improving the efficiency of such designs. PMID:27861485

Design and Study of a LOX/GH2 Throttleable Swirl Injector for Rocket Applications

NASA Technical Reports Server (NTRS)

Greene, Christopher; Woodward, Roger; Pal, Sibtosh; Santoro, Robert; Garcia, Roberto (Technical Monitor)

2002-01-01

A LOX/GH2 swirl injector was designed for a 10:1 propellant throttling range. To accomplish this, a dual LOX (liquid oxygen) manifold was used feeding a single common vortex chamber of the swirl element. Hot-fire experiments were conducting for rocket chamber pressures from 80 to 800 psia at a mixture ratio of nominally 6.0 using steady flow, single-point-per-firing cases as well as dynamic throttling conditions. Low frequency (mean) and high frequency (fluctuating) pressure transducer data, flow meter measurements, and Raman spectroscopy images for mixing information were obtained. The injector design, experimental setup, low frequency pressure data, and injector performance analysis will be presented. C efficiency was very high (approximately 100%) at the middle of the throttle-able range with somewhat lower performance at the high and low ends. From the analysis of discreet steady state operating conditions, injector pressure drop was slightly higher than predicted with an inviscid analysis, but otherwise agreed well across the design throttling range. Analysis of the dynamic throttling data indicates that the injector may experience transient conditions that effect pressure drop and performance when compared to steady state results.

Experimental and Numerical Investigation of Vortical Structures in Lean Premixed Swirl-Stabilized Combustion

NASA Astrophysics Data System (ADS)

Taamallah, Soufien; Chakroun, Nadim; Shanbhogue, Santosh; Kewlani, Gaurav; Ghoniem, Ahmed

2015-11-01

A combined experimental and LES investigation is performed to identify the origin of major flow dynamics and vortical structures in a model gas turbine's swirl-stabilized turbulent combustor. Swirling flows in combustion lead to the formation of complex flow dynamics and vortical structures that can interact with flames and influence its stabilization. Our experimental results for non-reacting flow show the existence of large scale precession motion. The precessing vortex core (PVC) dynamics disappears with combustion but only above a threshold of equivalence ratio. In addition, large scale vortices along the inner shear layer (ISL) are observed. These structures interact with the ISL stabilized flame and contribute to its wrinkling. Next, the LES setup is validated against the flow field's low-order statistics and point temperature measurement in relevant areas of the chamber. Finally, we show that LES is capable of predicting the precession motion as well as the ISL vortices in the reacting case: we find that ISL vortices originate from a vortex core that is formed right downstream of the swirler's centerbody. The vortex core has a conical spiral shape resembling a corkscrew that interacts - as it winds out - with the flame when it reaches the ISL.

Modeling of classical swirl injector dynamics

NASA Astrophysics Data System (ADS)

Ismailov, Maksud M.

The knowledge of the dynamics of a swirl injector is crucial in designing a stable liquid rocket engine. Since the swirl injector is a complex fluid flow device in itself, not much work has been conducted to describe its dynamics either analytically or by using computational fluid dynamics techniques. Even the experimental observation is limited up to date. Thus far, there exists an analytical linear theory by Bazarov [1], which is based on long-wave disturbances traveling on the free surface of the injector core. This theory does not account for variation of the nozzle reflection coefficient as a function of disturbance frequency, and yields a response function which is strongly dependent on the so called artificial viscosity factor. This causes an uncertainty in designing an injector for the given operational combustion instability frequencies in the rocket engine. In this work, the author has studied alternative techniques to describe the swirl injector response, both analytically and computationally. In the analytical part, by using the linear small perturbation analysis, the entire phenomenon of unsteady flow in swirl injectors is dissected into fundamental components, which are the phenomena of disturbance wave refraction and reflection, and vortex chamber resonance. This reveals the nature of flow instability and the driving factors leading to maximum injector response. In the computational part, by employing the nonlinear boundary element method (BEM), the author sets the boundary conditions such that they closely simulate those in the analytical part. The simulation results then show distinct peak responses at frequencies that are coincident with those resonant frequencies predicted in the analytical part. Moreover, a cold flow test of the injector related to this study also shows a clear growth of instability with its maximum amplitude at the first fundamental frequency predicted both by analytical methods and BEM. It shall be noted however that Bazarov's theory does not predict the resonant peaks. Overall this methodology provides clearer understanding of the injector dynamics compared to Bazarov's. Even though the exact value of response is not possible to obtain at this stage of theoretical, computational, and experimental investigation, this methodology sets the starting point from where the theoretical description of reflection/refraction, resonance, and their interaction between each other may be refined to higher order to obtain its more precise value.

Numerical modeling of a vortex stabilized arcjet

NASA Astrophysics Data System (ADS)

Pawlas, Gary Edward

Arcjet thrusters are being actively considered for use in Earth orbit maneuvering applications. Satellite station-keeping is an example of a maneuvering application requiring the low thrust, high specific impulse of an arcjet. Experimental studies are currently the chief means of determining an optimal thruster configuration. Earlier numerical studies have failed to include all of the effects found in typical arcjets including complex geometries, viscosity and swirling flow. Arcjet geometries are large area ratio converging-diverging nozzles with centerbodies in the subsonic portion of the nozzle. The nozzle walls serve as the anode while the centerbody functions as the cathode. Viscous effects are important because the Reynolds number, based on the throat radius, is typically less than 1,000. Experimental studies have shown a swirl or circumferential velocity component stabilizes a constricted arc. The equations are described which governs the flow through a constricted arcjet thruster. An assumption that the flowfield is in local thermodynamic equilibrium leads to a single fluid plasma temperature model. An order of magnitude analysis reveals the governing fluid mechanics equations are uncoupled from the electromagnetic field equations. A numerical method is developed to solve the governing fluid mechanics equations, the Thin Layer Navier-Stokes equations. A coordinate transformation is used in deriving the governing equations to simplify the application of boundary conditions in complex geometries. An axisymmetric formulation is employed to include the swirl velocity component as well as the axial and redial velocity components. The numerical method is an implicit finite-volume technique and allows for large time steps to reach a converged steady-state solution. The inviscid fluxes are flux-split and Gauss-Seidel line relaxation is used to accelerate convergence. 'Converging diverging' nozzles with exit-to-throat area ratios up to 100:1 and annual nozzles were examined. Comparisons with experimental data and previous numerical results were in excellent agreement. Quantities examined included Mach number and static wall pressure distributions, and oblique shock structures.

Association of Sugar-Sweetened Beverage Intake during Infancy with Dental Caries in 6-year-olds

PubMed Central

Lin, Mei; Onufrak, Stephen; Li, Ruowei

2015-01-01

To examine whether sugar-sweetened beverage (SSB) intake during infancy is associated with dental caries by age 6, a longitudinal analysis of 1,274 U.S. children was conducted using data from the 2005-2007 Infant Feeding Practices Study II and the 2012 Follow-up Study at 6 years of age. The exposure variables were maternal-reported SSB intakes during infancy (i.e., any SSB intake during infancy, age at SSB introduction during infancy, and average frequency of SSB intake during 10-12 months of age). The outcome variable was maternal-reported dental caries of their 6-year-old in his/her lifetime. Multivariable logistic regression analyses were used to calculate adjusted odds ratios (aOR) for associations of SSB intake during infancy with having dental caries among 6-year-olds after controlling for baseline characteristics of children and mothers and child's tooth brushing habits and sweet food intake at follow-up. Based on maternal recall, almost 40% of 6-year-olds had dental caries in their lifetime. Adjusted odds of having dental caries was significantly associated with higher frequency of SSB intake during 10-12 months (aOR=1.83 for ≥3 times/week, vs. none). Any SSB intake during infancy and age at SSB introduction during infancy were not associated with dental caries. In conclusion, frequent SSB intake during 10-12 months of age significantly increased the likelihood of having dental caries among 6-year-olds. Late infancy may be an important time for mothers to establish healthy beverage practices for their children. These findings can be used to inform efforts to reduce dental caries among children. PMID:25713788

Dairy intake and related self-regulation improved in college students using online nutrition education.

PubMed

Poddar, Kavita H; Hosig, Kathy W; Anderson-Bill, Eileen S; Nickols-Richardson, Sharon M; Duncan, Susan E

2012-12-01

Dairy intake by college students is markedly lower than recommendations. Interventions to improve dairy intake based on Social Cognitive Theory (SCT) have potential to successfully change behavior by improving mediators that influence dietary choices. We aimed to use SCT to improve social support, self-efficacy, outcome expectations, self-regulation, and behavior related to dairy intake in college students. We conducted a randomized nutrition education intervention. Participants included 211 college students (mean age 20.2 ± 0.1 years; 63% women and 37% men) recruited from a university campus. Participants in the intervention group (n=107) and comparison group (n=104) received an 8-week dairy intake or stress management intervention, respectively, via electronic mail. Data collection included dairy intake from 7-day food records and SCT variables from questionnaires administered during January 2008 and April 2008. Changes in dairy intake and SCT variables (ie, social support, self-efficacy, outcome expectations, and self-regulation). Multivariate analysis of covariance, with age and sex as covariates (P<0.05). Ninety-one percent of participants (n=97 intervention, n=94 comparison) provided data; complete data were analyzed for 85% of participants (n=90 intervention, n=89 comparison). Participants in the intervention group reported higher intake of total dairy foods (P=0.012) and improved use of self-regulation strategies for consuming three servings per day of total dairy (P=0.000) and low-fat dairy foods (P=0.002) following the intervention. Nutrition education via electronic mail based on an SCT model improved total dairy intake and self-regulation. Participants reported increased dairy intake and better use of self-regulation strategies. Future interventions should focus on benefits of consuming low-fat vs higher-fat dairy foods. Copyright © 2012 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Associations among food insecurity, acculturation, demographic factors, and fruit and vegetable intake at home in Hispanic children.

PubMed

Dave, Jayna M; Evans, Alexandra E; Saunders, Ruth P; Watkins, Ken W; Pfeiffer, Karin A

2009-04-01

The purpose of this cross-sectional pilot study was to examine associations between food insecurity, acculturation, demographic factors, and children's fruit and vegetable intake among a sample of Hispanic children ages 5 to 12 years. A convenience sample of 184 parents of low socioeconomic status completed one-time, self-administered questionnaires assessing demographic information, acculturation, and food insecurity in the spring of 2006. In addition, children's fruit and vegetable intake at home was measured using a validated seven-item index. Parents were recruited through local elementary schools in San Antonio, TX. Pearson and Spearman correlations were used to examine the associations between the variables. t tests were used to explore the differences in means of children's fruit and vegetable intake at home for acculturation and food insecurity levels. Statistical significance was set at P<0.05. Significant correlations were found between demographic variables, acculturation, food insecurity, and children's fruit and vegetable intake at home. The overall mean fruit and vegetable intake at home was 1.04+/-0.63 (mean+/-standard deviation) servings per day. Higher rates of acculturation and higher rates of food insecurity were associated with lower fruit and vegetable intake at home. The findings reported in this study suggest a need for culturally tailored interventions targeting Hispanic children because fruit and vegetable intake at home among Hispanic children was low, regardless of the level of acculturation or food insecurity.

Adolescent fruit and vegetable intake: influence of family support and moderation by home availability of relationships with afrocentric values and taste preferences.

PubMed

Di Noia, Jennifer; Byrd-Bredbenner, Carol

2013-06-01

Economically disadvantaged African-American adolescents have fruit and vegetable (F/V) intakes that are less than optimal. To facilitate intervention planning to address low F/V intake in this population, an understanding of determinants of youths' intake is needed. The influence of determinants consistently supported by evidence (ie, home F/V availability, F/V taste preferences, and parental modeling/intake) and variables hypothesized to influence intake in the targeted population (ie, family support for F/V consumption and Afrocentric values) were examined. Participants were African-American adolescents recruited in 2011 through summer camps serving low-income youths (N=93). Youths completed a cross-sectional survey. Hierarchical logistic regression analysis was used to examine whether availability directly influenced (ie, explained variations in) intake and whether it moderated (ie, affected the direction and/or strength of) the relationships between the other hypothesized determinants and intake. The dependent variable was intake of five or more daily servings of F/V estimated with the Block 7-item food frequency questionnaire. Family support was directly related to intake (odds ratio=1.062; 95% CI 1.007 to 1.120; P=0.026). The relationships between F/V intake and taste preferences and Afrocentric values were moderated by (ie, differed based on) home F/V availability. When availability was high, taste preferences (odds ratio=1.081; 95% CI 1.007 to 1.161; P=0.032) and Afrocentric values (OR=2.504; 95% CI 1.303 to 4.811; P=0.006) had positive influences on intake. To enhance intervention effectiveness, more research is warranted on approaches for increasing home F/V availability and family support for F/V consumption in the targeted population. Copyright © 2013 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Self-monitoring urinary salt excretion in adults: A novel education program for restricting dietary salt intake

PubMed Central

YASUTAKE, KENICHIRO; SAWANO, KAYOKO; YAMAGUCHI, SHOKO; SAKAI, HIROKO; AMADERA, HATSUMI; TSUCHIHASHI, TAKUYA

2011-01-01

This study aimed to examine the usefulness of the self-monitoring of urinary salt excretion for educating individuals about the risk of excessive dietary salt intake. The subjects were 30 volunteers (15 men and 15 women) not consuming anti-hypertensive medication. The subjects measured urinary salt excretion at home for 4 weeks using a self-monitoring device. Blood pressure (BP), anthropometric variables and nutritional variables (by a dietary-habits questionnaire) were measured before and after the measurement of urinary salt excretion. Statistical analyses were performed, including paired t-tests, Chi-square test, Pearson’s product moment correlation coefficient and multiple linear regression analysis. In all subjects, the average urinary salt excretion over 4 weeks was 8.05±1.61 g/day and the range (maximum-minimum value) was 5.58±2.15 g/day. Salt excretion decreased significantly in weeks 3 and 4 (P<0.05 and P<0.01, respectively). Diastolic BP decreased from 77.7±14.3 (at baseline) to 74.3±13.3 after 4 weeks (P<0.05), while systolic BP and anthropometric variables remained unchanged. Nutrition surveys indicated that energy intake was correlated with salt intake both before and after the measurements; changes in both variables during the observation period were correlated (r=0.40, P<0.05). The percentage of subjects who were aware of the restriction in dietary salt intake increased from 47 to 90%. In conclusion, daily monitoring of the amount of urinary salt excretion using a self-monitoring device appears to be an effective educational tool for improving the quality of life of healthy adults. PMID:22977549

Self-monitoring urinary salt excretion in adults: A novel education program for restricting dietary salt intake.

PubMed

Yasutake, Kenichiro; Sawano, Kayoko; Yamaguchi, Shoko; Sakai, Hiroko; Amadera, Hatsumi; Tsuchihashi, Takuya

2011-07-01

This study aimed to examine the usefulness of the self-monitoring of urinary salt excretion for educating individuals about the risk of excessive dietary salt intake. The subjects were 30 volunteers (15 men and 15 women) not consuming anti-hypertensive medication. The subjects measured urinary salt excretion at home for 4 weeks using a self-monitoring device. Blood pressure (BP), anthropometric variables and nutritional variables (by a dietary-habits questionnaire) were measured before and after the measurement of urinary salt excretion. Statistical analyses were performed, including paired t-tests, Chi-square test, Pearson's product moment correlation coefficient and multiple linear regression analysis. In all subjects, the average urinary salt excretion over 4 weeks was 8.05±1.61 g/day and the range (maximum-minimum value) was 5.58±2.15 g/day. Salt excretion decreased significantly in weeks 3 and 4 (P<0.05 and P<0.01, respectively). Diastolic BP decreased from 77.7±14.3 (at baseline) to 74.3±13.3 after 4 weeks (P<0.05), while systolic BP and anthropometric variables remained unchanged. Nutrition surveys indicated that energy intake was correlated with salt intake both before and after the measurements; changes in both variables during the observation period were correlated (r=0.40, P<0.05). The percentage of subjects who were aware of the restriction in dietary salt intake increased from 47 to 90%. In conclusion, daily monitoring of the amount of urinary salt excretion using a self-monitoring device appears to be an effective educational tool for improving the quality of life of healthy adults.

Dietary intake is independently associated with the maximal capacity for fat oxidation during exercise.

PubMed

Fletcher, Gareth; Eves, Frank F; Glover, Elisa I; Robinson, Scott L; Vernooij, Carlijn A; Thompson, Janice L; Wallis, Gareth A

2017-04-01

Background: Substantial interindividual variability exists in the maximal rate of fat oxidation (MFO) during exercise with potential implications for metabolic health. Although the diet can affect the metabolic response to exercise, the contribution of a self-selected diet to the interindividual variability in the MFO requires further clarification. Objective: We sought to identify whether recent, self-selected dietary intake independently predicts the MFO in healthy men and women. Design: The MFO and maximal oxygen uptake ([Formula: see text]O 2 max) were determined with the use of indirect calorimetry in 305 healthy volunteers [150 men and 155 women; mean ± SD age: 25 ± 6 y; body mass index (BMI; in kg/m 2 ): 23 ± 2]. Dual-energy X-ray absorptiometry was used to assess body composition with the self-reported physical activity level (SRPAL) and dietary intake determined in the 4 d before exercise testing. To minimize potential confounding with typically observed sex-related differences (e.g., body composition), predictor variables were mean-centered by sex. In the analyses, hierarchical multiple linear regressions were used to quantify each variable's influence on the MFO. Results: The mean absolute MFO was 0.55 ± 0.19 g/min (range: 0.19-1.13 g/min). A total of 44.4% of the interindividual variability in the MFO was explained by the [Formula: see text]O 2 max, sex, and SRPAL with dietary carbohydrate (carbohydrate; negative association with the MFO) and fat intake (positive association) associated with an additional 3.2% of the variance. When expressed relative to fat-free mass (FFM), the MFO was 10.8 ± 3.2 mg · kg FFM -1 · min -1 (range: 3.5-20.7 mg · kg FFM -1 · min -1 ) with 16.6% of the variability explained by the [Formula: see text]O 2 max, sex, and SRPAL; dietary carbohydrate and fat intakes together explained an additional 2.6% of the variability. Biological sex was an independent determinant of the MFO with women showing a higher MFO [men: 10.3 ± 3.1 mg · kg FFM -1 · min -1 (3.5-19.9 mg · kg FFM -1 · min -1 ); women: 11.2 ± 3.3 mg · kg FFM -1 · min -1 (4.6-20.7 mg · kg FFM -1 · min -1 ); P < 0.05]. Conclusion: Considered alongside other robust determinants, dietary carbohydrate and fat intake make modest but independent contributions to the interindividual variability in the capacity to oxidize fat during exercise. This trial was registered at clinicaltrials.gov as NCT02070055.

Sociodemographic and Behavioral Factors Associated with Added Sugars Intake among US Adults

PubMed Central

Park, Sohyun; Thompson, Frances E.; McGuire, Lisa C.; Pan, Liping; Galuska, Deborah A.; Blanck, Heidi M.

2016-01-01

Background Reducing added sugars intake is one of the Healthy People 2020 objectives. High added sugars intake may be associated with adverse health consequences. Objective This cross-sectional study identified sociodemographic and behavioral characteristics associated with added sugars intake among US adults (18 years and older) using the 2010 National Health Interview Survey data (n=24,967). Methods The outcome variable was added sugars intake from foods and beverages using scoring algorithms to convert dietary screener frequency responses on nine items to estimates of individual dietary intake of added sugars in teaspoons per day. Added sugars intake was categorized into tertiles (lowest, middle, highest) stratified by sex. The explanatory variables were sociodemographic and behavioral characteristics. Multinomial logistic regression was used to estimate the adjusted odds ratios for the highest and middle tertile added sugars intake groups as compared with the lowest tertile group. Results Estimated median added sugars intake was 17.6 tsp/d for men and 11.7 tsp/d for women. For men and women, those who had significantly greater odds for being in the highest tertile of added sugars intake (men: ≥22.0 tsp/d; women: ≥14.6 tsp/d) were younger, less educated, had lower income, were less physically active, were current smokers, and were former or current infrequent/light drinkers, whereas non-Hispanic other/multiracial and those living in the West had significantly lower odds for being in the highest tertile of added sugars intake. Different patterns were found by sex. Non-Hispanic black men had lower odds for being in the highest tertile of added sugars intake, whereas non-Hispanic black women had greater odds for being in the highest tertile. Conclusions One in three men consumed ≥22.0 tsp added sugars and one in three women consumed ≥14.6 tsp added sugars daily. Higher added sugars intake was associated with various sociodemographic and behavioral characteristics; this information can inform efforts to design programs and policies specific to high-intake populations. PMID:27236642

Acute effect of oral flavonoid-rich dark chocolate intake on coronary circulation, as compared with non-flavonoid white chocolate, by transthoracic Doppler echocardiography in healthy adults.

PubMed

Shiina, Yumi; Funabashi, Nobusada; Lee, Kwangho; Murayama, Taichi; Nakamura, Koki; Wakatsuki, Yu; Daimon, Masao; Komuro, Issei

2009-01-24

To assess the effects of the oral intake of flavonoid-rich dark chocolate on coronary circulation, we measured coronary flow velocity reserve (CFVR) by noninvasive transthoracic Doppler echocardiography (TTDE) in healthy adult subjects. The study was a randomized, single-blind design conducted for 2 weeks in 39 healthy men (mean age 29.7+/-3.9 years, range 23-40 years). Subjects were randomly assigned a daily intake of either flavonoid-rich dark chocolate (Meiji Black Chocolate 45 g, Meiji Seika kaisya Ltd, including cacao polyphenol 550 mg/day, 200 kcal) or non-flavonoid white chocolate (Meiji White Chocolate 35 g, Meiji Seika kaisya Ltd, including cacao polyphenol 0 mg/day, 140 kcal) as a control. CFVR was recorded by TTDE, and assessed before and after 2 weeks of intake. At the same time, we also assessed serum asymmetric dimethylarginine, 8-isoprostanes, and malondialdehyde-modified low-density lipoprotein (MDA-LDL) as markers of oxidative stress. Flavonoid-rich dark chocolate consumption significantly improved CFVR (3.38+/-0.49 before intake, 4.28+/-0.85 after intake; p<0.01), whereas non-flavonoid white chocolate consumption did not (3.28+/-0.49 before intake, 3.16+/-0.49 after intake; p=0.44). All predictor variables were used as dependent variables in a multiple regression model of the incremental change in CFVR after 2 weeks of chocolate intake. Intake of dark (but not white) chocolate, MDA-LDL, triglyceride (TG) and heart rate (HR) significantly influenced the change of CFVR after 2 weeks of intake (p<0.01) according to the multiple regression formula: Y=1.01X(1)-0.005X(2)-0.003X(3)-0.017X4 (Y=change in CFVR after 2 weeks of chocolate intake, X1=intake of dark (but not white) chocolate, X2=MDA-LDL, X3=TG, X4=HR). Flavonoid-rich dark chocolate intake significantly improved coronary circulation in healthy adults, independent of changes in oxidative stress parameters, blood pressure and lipid profile, whereas non-flavonoid white chocolate had no such effects.

Sociodemographic and Behavioral Factors Associated with Added Sugars Intake among US Adults.

PubMed

Park, Sohyun; Thompson, Frances E; McGuire, Lisa C; Pan, Liping; Galuska, Deborah A; Blanck, Heidi M

2016-10-01

Reducing added sugars intake is one of the Healthy People 2020 objectives. High added sugars intake may be associated with adverse health consequences. This cross-sectional study identified sociodemographic and behavioral characteristics associated with added sugars intake among US adults (18 years and older) using the 2010 National Health Interview Survey data (n=24,967). The outcome variable was added sugars intake from foods and beverages using scoring algorithms to convert dietary screener frequency responses on nine items to estimates of individual dietary intake of added sugars in teaspoons per day. Added sugars intake was categorized into tertiles (lowest, middle, highest) stratified by sex. The explanatory variables were sociodemographic and behavioral characteristics. Multinomial logistic regression was used to estimate the adjusted odds ratios for the highest and middle tertile added sugars intake groups as compared with the lowest tertile group. Estimated median added sugars intake was 17.6 tsp/d for men and 11.7 tsp/d for women. For men and women, those who had significantly greater odds for being in the highest tertile of added sugars intake (men: ≥22.0 tsp/d; women: ≥14.6 tsp/d) were younger, less educated, had lower income, were less physically active, were current smokers, and were former or current infrequent/light drinkers, whereas non-Hispanic other/multiracial and those living in the West had significantly lower odds for being in the highest tertile of added sugars intake. Different patterns were found by sex. Non-Hispanic black men had lower odds for being in the highest tertile of added sugars intake, whereas non-Hispanic black women had greater odds for being in the highest tertile. One in three men consumed ≥22.0 tsp added sugars and one in three women consumed ≥14.6 tsp added sugars daily. Higher added sugars intake was associated with various sociodemographic and behavioral characteristics; this information can inform efforts to design programs and policies specific to high-intake populations. Published by Elsevier Inc.

Association between Dietary Intake and Coronary Artery Calcification in Non-Dialysis Chronic Kidney Disease: The PROGREDIR Study

PubMed Central

Gómez, Luz Marina; Marchioni, Dirce Maria Lobo; dos Anjos, Fernanda Silva Nogueira; Molina, Maria del Carmen Bisi; Lotufo, Paulo Andrade; Benseñor, Isabela Judith Martins; Titan, Silvia Maria de Oliveira

2018-01-01

Coronary artery calcification (CAC) is a widespread condition in chronic kidney disease (CKD). Diet may play an important role in CAC, but this role is not clear. This study evaluated the association between macro-and micronutrient intakes and CAC in non-dialysis CKD patients. We analyzed the baseline data from 454 participants of the PROGREDIR study. Dietary intake was evaluated by a food frequency questionnaire. CAC was measured by computed tomography. After exclusion of participants with a coronary stent, 373 people remained for the analyses. The highest tertile of CAC was directly associated with the intake of phosphorus, calcium and magnesium. There was a higher intake of pantothenic acid and potassium in the second tertile. After adjustments for confounding variables, the intake of pantothenic acid, phosphorus, calcium and potassium remained associated with CAC in the generalized linear mixed models. In order to handle the collinearity between these nutrients, we used the LASSO (least absolute shrinkage and selection operator) regression to evaluate the nutrients associated with CAC variability. In this approach, the nutrients that most explained the variance of CAC were phosphorus, calcium and potassium. Prospective studies are needed to confirm these findings and assess the role of interventions regarding these micronutrients on CAC prevention and progression. PMID:29562658

Association between Dietary Intake and Coronary Artery Calcification in Non-Dialysis Chronic Kidney Disease: The PROGREDIR Study.

PubMed

Machado, Alisson Diego; Gómez, Luz Marina; Marchioni, Dirce Maria Lobo; Dos Anjos, Fernanda Silva Nogueira; Molina, Maria Del Carmen Bisi; Lotufo, Paulo Andrade; Benseñor, Isabela Judith Martins; Titan, Silvia Maria de Oliveira

2018-03-19

Coronary artery calcification (CAC) is a widespread condition in chronic kidney disease (CKD). Diet may play an important role in CAC, but this role is not clear. This study evaluated the association between macro-and micronutrient intakes and CAC in non-dialysis CKD patients. We analyzed the baseline data from 454 participants of the PROGREDIR study. Dietary intake was evaluated by a food frequency questionnaire. CAC was measured by computed tomography. After exclusion of participants with a coronary stent, 373 people remained for the analyses. The highest tertile of CAC was directly associated with the intake of phosphorus, calcium and magnesium. There was a higher intake of pantothenic acid and potassium in the second tertile. After adjustments for confounding variables, the intake of pantothenic acid, phosphorus, calcium and potassium remained associated with CAC in the generalized linear mixed models. In order to handle the collinearity between these nutrients, we used the LASSO (least absolute shrinkage and selection operator) regression to evaluate the nutrients associated with CAC variability. In this approach, the nutrients that most explained the variance of CAC were phosphorus, calcium and potassium. Prospective studies are needed to confirm these findings and assess the role of interventions regarding these micronutrients on CAC prevention and progression.

Dental caries and beverage consumption in young children.

PubMed

Marshall, Teresa A; Levy, Steven M; Broffitt, Barbara; Warren, John J; Eichenberger-Gilmore, Julie M; Burns, Trudy L; Stumbo, Phyllis J

2003-09-01

Dental caries is a common, chronic disease of childhood. The impact of contemporary changes in beverage patterns, specifically decreased milk intakes and increased 100% juice and soda pop intakes, on dental caries in young children is unknown. We describe associations among caries experience and intakes of dairy foods, sugared beverages, and nutrients and overall diet quality in young children. Subjects (n = 642) are members of the Iowa Fluoride Study, a cohort followed from birth. Food and nutrient intakes were obtained from 3-day diet records analyzed at 1 (n = 636), 2 (n = 525), 3 (n = 441), 4 (n = 410), and 5 (n = 417) years and cumulatively for 1 through 5 (n = 396) years of age. Diet quality was defined by nutrient adequacy ratios (NARs) and calculated as the ratio of nutrient intake to Recommended Dietary Allowance/Adequate Intake. Caries were identified during dental examinations by 2 trained and calibrated dentists at 4 to 7 years of age. Examinations were visual, but a dental explorer was used to confirm questionable findings. Caries experience was assessed at both the tooth and the surface levels. Data were analyzed using SAS. The Wilcoxon rank sum test was used to compare food intakes, nutrient intakes, and NARs of subjects with and without caries experience. Logistic and Tobit regression analyses were used to identify associations among diet variables and caries experience and to develop models to predict caries experience. Not all relationships between food intakes and NARs and caries experience were linear; therefore, categorical variables were used to develop models to predict caries experience. Food and beverage intakes were categorized as none, low, and high intakes, and NARs were categorized as inadequate, low adequate, and high adequate. Subjects with caries had lower median intakes of milk at 2 and 3 years of age than subjects without caries. Subjects with caries had higher median intakes of regular (sugared) soda pop at 2, 3, 4, and 5 years and for 1 through 5 years; regular beverages from powder at 1, 4, and 5 years and for 1 through 5 years; and total sugared beverages at 4 and 5 years than subjects without caries. Logistic regression models were developed for exposure variables at 1, 2, 3, 4, and 5 years and for 1 through 5 years to predict any caries experience at 4 to 7 years of age. Age at dental examination was retained in models at all ages. Children with 0 intake (vs low and high intakes) of regular beverages from powder at 1 year, regular soda pop at 2 and 3 years, and sugar-free beverages from powder at 5 years had a decreased risk of caries experience. High intakes of regular beverages from powder at 4 and 5 years and for 1 through 5 years and regular soda pop at 5 years and for 1 through 5 years were associated with significantly increased odds of caries experience relative to subjects with none or low intakes. Low (vs none or high) intakes of 100% juice at 5 years were associated with decreased caries experience. In general, inadequate intakes (vs low adequate or high adequate intakes) of nutrients (eg, riboflavin, copper, vitamin D, vitamin B(12)) were associated with increased caries experience and low adequate intakes (vs inadequate or high adequate intakes) of nutrients (eg, vitamin B(12), vitamin C) were associated with decreased caries experience. An exception was vitamin E; either low or high adequate intakes were associated with increased caries experience at various ages. Multivariable Tobit regression models were developed for 1- through 5-year exposure variables to predict the number of tooth surfaces with caries experience at 4 to 7 years of age. Age at dental examination showed a significant positive association and fluoride exposure showed a significant negative association with the number of tooth surfaces with caries experience in the final model. Low intakes of nonmilk dairy foods (vs high intakes; all subjects had some nonmilk dairy intakes) and high adequate intakes of vitamin C (vs inadequate and low adequate intakes) were associated with fewer tooth surfaces having caries experience. High intakes of regular soda pop (vs none and low intakes) were associated with more tooth surfaces having caries experience. Results of our study suggest that contemporary changes in beverage patterns, particularly the increase in soda pop consumption, have the potential to increase dental caries rates in children. Consumption of regular soda pop, regular powdered beverages, and, to a lesser extent, 100% juice was associated with increased caries risk. Milk had a neutral association with caries. Associations between different types of sugared beverages and caries experience were not equivalent, which could be attributable to the different sugar compositions of the beverages or different roles in the diet. Our data support contemporary dietary guidelines for children: consume 2 or more servings of dairy foods daily, limit intake of 100% juice to 4 to 6 oz daily, and restrict other sugared beverages to occasional use. Pediatricians, pediatric nurse practitioners, and dietitians are in a position to support pediatric dentists in providing preventive guidance to parents of young children.

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

PubMed

Karthikeya Sharma, T

2015-11-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

PubMed Central

Karthikeya Sharma, T.

2014-01-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied. PMID:26644918

Factors associated with added sugars intake among adolescents living in São Paulo, Brazil.

PubMed

Colucci, Ana Carolina A; Cesar, Chester L G; Marchioni, Dirce M L; Fisberg, Regina M

2012-08-01

To measure added sugars intake among adolescents and describe its demographic, socioeconomic, and nutritional status determinants. The study was conducted based on a household survey carried out between March and December 2003. Food intake was assessed through 24-hour food recalls, and an adjustment approach was applied using external variance estimates derived from 195 adolescents of the same age in 2007. Population-based cross-sectional study, city of São Paulo, Brazil. Seven hundred and ninety-three male (n = 410) and female (n = 383) adolescents aged 10-19 years. MEASURE OF OUTCOME: Foods with greater contributions toward the added sugars intake were identified. Multiple linear regression analysis was performed, with calories from added sugars as the dependent continuous variable and the remaining factors (socioeconomic, demographic, lifestyle, household condition, and food intake) as independent variables. The average contribution of added sugars to total energy value was 12.28% (95% confidence interval [CI]: 11.87-12.70) with no statistically significant sex difference (p > 0.05). Soft drinks were a major source of added sugars among the adolescents (34.2% among males and 32.0% among females), followed by sugars (sucrose and honey) and chocolate powder (around 11%). In the multiple linear regression analysis, the head of household's education level and calories from protein, fats, and carbohydrates other than sugars had an independent effect on added sugars intake. This study showed that the percentage contribution of added sugars to energy intake among adolescents in the city of São Paulo, Brazil, was above the current recommended levels. Socioeconomic condition (represented by the head of the household's education level) and macronutrient intake were shown to be determinants of sugars intake.

Dietary intakes differ between renal transplant recipients living in patient hotels versus home.

PubMed

Kahra, Terhi; Jenssen, Trond; Løvik, Astrid

2004-04-01

To compare dietary intake and health-related quality of life approximately 6 to 10 weeks after renal transplantation in patients living at home and at a patient hotel, and how the patients were following a heart-healthy diet according to the current American Heart Association guidelines. Cross-sectional observational study. Outpatient clinic at Rikshospitalet University Hospital, Norway. Forty renal transplant patients, 20 patients (14 men and 6 women) in both groups. There were 4 diabetic patients in each group. Dietary intake was assessed by 4-day dietary records. Health-related quality of life was investigated by the SF-36 questionnaire. The main outcome variables were daily energy intake and intakes of protein, total fat, saturated fat, cholesterol, fiber, and fruit and vegetables. The variables were tested by 2-sample t-tests, and significance was set at.05. There was no statistically significant difference in daily energy intake between the groups (P =.08), but there were significantly higher daily intakes of protein (P =.003), total fat (P =.03), monounsaturated fat (P =.02), cholesterol (P =.04), fiber (P =.02), calcium (P =.03), and fruit and vegetables (P =.03) in the group living at the patient hotel. The mean intake of saturated fat was 14.5% of total energy in the group living at home and 14.6% in the group living at the patient hotel. There were no significant differences in health-related quality of life between the groups. The results suggest that there are differences in dietary intake in renal transplant patients living at home compared with those at a patient hotel. It seems that neither of the groups follows current guidelines for reducing the risk of cardiovascular disease.

Children's sugar-sweetened beverages consumption: associations with family and home-related factors, differences within ethnic groups explored.

PubMed

van de Gaar, V M; van Grieken, A; Jansen, W; Raat, H

2017-02-14

The consumption of sugar-sweetened beverages (SSB) may contribute to the development of overweight among children. The present study aimed to evaluate associations between family and home-related factors and children's SSB consumption. We explored associations within ethnic background of the child. Cross-sectional data from the population-based 'Water Campaign' study were used. Parents (n = 644) of primary school children (6-13 years) completed a questionnaire on socio-demographic characteristics, family and home-related factors and child's SSB intake. The family and home-related factors under study were: cognitive variables (e.g. parental attitude, subjective norm), environmental variables (e.g. availability of SSB, parenting practices), and habitual variables (e.g. habit strength, taste preference). Regression analyses were used to evaluate the associations between family and home-related factors and child's SSB intake (p < 0.05). Mean age of the children was 9.4 years (SD: 1.8) and 54.1% were girls. The child's average SSB intake was 0.9 litres (SD: 0.6) per day. Child's age, parents' subjective norm, parenting practices, and parental modelling were positively associated with the child's SSB intake. The availability of SSB at home and school and parental attitude were negatively associated with the child's SSB intake. The associations under study differed according to the child's ethnic background, with the explained variance of the full models ranging from 8.7% for children from Moroccan or Turkish ethnic background to 44.4% for children with Dutch ethnic background. Our results provide support for interventions targeting children's SSB intake focussing on the identified family and home-related factors, with active participation of parents. Also, the relationships between these factors and the child's SSB intake differed for children with distinct ethnic backgrounds. Therefore, we would recommend to tailor interventions taking into account the ethnic background of the family. Number NTR3400 ; date April 4th 2012; retrospectively registered.

Safety and efficacy of cocoa flavanol intake in healthy adults: a randomized, controlled, double-masked trial.

PubMed

Ottaviani, Javier I; Balz, Marion; Kimball, Jennifer; Ensunsa, Jodi L; Fong, Reedmond; Momma, Tony Y; Kwik-Uribe, Catherine; Schroeter, Hagen; Keen, Carl L

2015-12-01

Evidence from dietary intervention studies shows that the intake of flavanols and procyanidins can be beneficial for cardiovascular health. Nevertheless, there is a clear need for advancing our understanding with regard to safe amounts of intake for these bioactives. The aim was to investigate in healthy adults the effects of cocoa flavanol (CF) intake amount and intake duration on blood pressure, platelet function, metabolic variables, and potential adverse events (AEs). This investigation consisted of 2 parts. Part 1 was an open-label, intake-amount escalation study, in which 34 healthy adults (aged 35-55 y) consumed escalating amounts of CFs, ranging from 1000 to 2000 mg/d over 6 wk. Primary outcomes were blood pressure and platelet function, select metabolic variables, and the occurrence and severity of AEs. Secondary outcomes included plasma concentrations of CF-derived metabolites and methylxanthines. On the basis of the outcomes of study part 1, and assessing the same outcome measures, part 2 of this investigation was a controlled, randomized, double-masked, 2-parallel-arm dietary intervention study in which healthy participants (aged 35-55 y) were asked to consume for 12 consecutive weeks up to 2000 mg CFs/d (n = 46) or a CF-free control (n = 28). Daily intake of up to 2000 mg CFs/d for 12 wk was not associated with significant changes in blood pressure or platelet function compared with CF-free controls in normotensive, healthy individuals who exhibited a very low risk of cardiovascular disease. There were no clinically relevant changes in the metabolic variables assessed in either of the groups. AEs reported were classified as mild in severity and did not significantly differ between study arms. The consumption of CFs in amounts up to 2000 mg/d for 12 wk was well tolerated in healthy men and women. This trial was registered at clinicaltrials.gov as NCT02447770 (part 1) and NCT02447783 (part 2). © 2015 American Society for Nutrition.

Correlation of magnesium intake with metabolic parameters, depression and physical activity in elderly type 2 diabetes patients: a cross-sectional study

PubMed Central

2012-01-01

Background Type 2 diabetes mellitus is a major global public health problem in the worldwide and is increasing in aging populations. Magnesium intake may be one of the most important factors for diabetes prevention and management. Low magnesium intake may exacerbate metabolic abnormalities. In this study, the relationships of magnesium intake with metabolic parameters, depression and physical activity in elderly patients with type 2 diabetes were investigated. Methods This cross-sectional study involved 210 type 2 diabetes patients aged 65 years and above. Participants were interviewed to obtain information on lifestyle and 24-hour dietary recall. Assessment of depression was based on DSM-IV criteria. Clinical variables measured included anthropometric measurements, blood pressure, and biochemical determinations of blood and urine samples. Linear regression was applied to determine the relationships of magnesium intake with nutritional variables and metabolic parameters. Results Among all patients, 88.6% had magnesium intake which was less than the dietary reference intake, and 37.1% had hypomagnesaemia. Metabolic syndromes and depression were associated with lower magnesium intake (p < 0.05). A positive relationship was found between magnesium intake and HDL-cholesterol (p = 0.005). Magnesium intake was inversely correlated with triglyceride, waist circumference, body fat percent and body mass index (p < 0.005). After controlling confounding factor, HDL-cholesterol was significantly higher with increasing quartile of magnesium intake (p for trend = 0005). Waist circumference, body fat percentage, and body mass index were significantly lower with increase quartile of magnesium intake (p for trend < 0.001). The odds of depression, central obesity, high body fat percentage, and high body mass index were significantly lower with increasing quartile of magnesium intake (p for trend < 0.05). In addition, magnesium intake was related to high physical activity level and demonstrated lower serum magnesium levels. Serum magnesium was not significantly associated with metabolic parameters. Conclusions The majority of elderly type 2 diabetes who have low magnesium intake may compound this deficiency with metabolic abnormalities and depression. Future studies should determine the effects of increased magnesium intake or magnesium supplementation on metabolic control and depression in elderly people with type 2 diabetes. PMID:22695027

So Many Brands and Varieties to Choose from: Does This Compromise the Control of Food Intake in Humans?

PubMed

Hardman, Charlotte A; Ferriday, Danielle; Kyle, Lesley; Rogers, Peter J; Brunstrom, Jeffrey M

2015-01-01

The recent rise in obesity is widely attributed to changes in the dietary environment (e.g., increased availability of energy-dense foods and larger portion sizes). However, a critical feature of our "obesogenic environment" may have been overlooked - the dramatic increase in "dietary variability" (the tendency for specific mass-produced foods to be available in numerous varieties that differ in energy content). In this study we tested the hypothesis that dietary variability compromises the control of food intake in humans. Specifically, we examined the effects of dietary variability in pepperoni pizza on two key outcome variables; i) compensation for calories in pepperoni pizza and ii) expectations about the satiating properties of pepperoni pizza (expected satiation). We reasoned that dietary variability might generate uncertainty about the postingestive effects of a food. An internet-based questionnaire was completed by 199 adults. This revealed substantial variation in exposure to different varieties of pepperoni pizza. In a follow-up study (n= 66; 65% female), high pizza variability was associated with i) poorer compensation for calories in pepperoni pizza and ii) lower expected satiation for pepperoni pizza. Furthermore, the effect of uncertainty on caloric compensation was moderated by individual differences in decision making (loss aversion). For the first time, these findings highlight a process by which dietary variability may compromise food-intake control in humans. This is important because it exposes a new feature of Western diets (processed foods in particular) that might contribute to overeating and obesity.

Paternal intake of folate and vitamins B6 and B12 before conception and risk of childhood acute lymphoblastic leukemia.

PubMed

Bailey, Helen D; Miller, Margaret; Greenop, Kathryn R; Bower, Carol; Attia, John; Marshall, Glenn M; Armstrong, Bruce K; Milne, Elizabeth

2014-12-01

We investigated whether paternal dietary intake of folate before conception is associated with the risk of childhood acute lymphoblastic leukemia (ALL) in a nationwide case-control study. Data on dietary folate intake during the 6 months before the child's conception were collected from 285 case fathers and 595 control fathers using a dietary questionnaire. Nutrient intake was quantified using a customized computer software package based on Australian food composition databases. Data on folate intake were analyzed using unconditional logistic regression, adjusting for study-matching variables, total energy, and potentially confounding variables. In a subset of 229 cases and 420 controls, data on vitamin B6 and vitamin B12 intake were also analyzed. No consistent associations were seen with paternal dietary intake of folate or vitamin B6. Higher levels of paternal dietary vitamin B12 were appeared to be associated with an increased risk of childhood ALL, with those in the highest tertile of consumption having an OR of 1.51 (0.97, 2.36). The use of supplements containing folate and vitamins B6 or B12 was rare. We did not find any biologically plausible evidence that paternal nutrition in the period leading up to conception was associated with childhood ALL. Our finding for vitamin B12 may be a chance finding, given the number of analyses performed, or be attributable to participation bias because parents with a tertiary education had the lowest level of B12 intake and tertiary education was more common among control than case parents.

Determinants of Blood Cell Omega-3 Fatty Acid Content

PubMed Central

Block, Robert C.; Harris, William S.; Pottala, James V.

2009-01-01

Background Although red blood cell eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) content (the Omega-3 Index) predicts cardiovascular death, the factors determining the Index are unknown. Methods In 704 outpatients, we undertook an investigation of the clinical determinants of the Index. Results Factors associated with the Index in decreasing order were: EPA+DHA supplement use, fish consumption frequency, triglyceride level, age, high cholesterol history, and smoking. These factors explained 59% of Index variability, with capsules/fish intake together accounting for 47%. The Index increased by 13% (p< 0.0001) for each serving level increase in fish intake and EPA+DHA supplementation correlated with a 58% increase (p< 0.0001) regardless of background fish intake (p=0.25; test for interaction). A 100 mg/dL decrease in serum triglycerides was associated with a 15% higher (p<0.0001) Index. Conclusions The intake of EPA+DHA-rich foods and supplements principally determined the Omega-3 Index, but explained only about half of the variability. PMID:19953197

Independence of heritable influences on the food intake of free-living humans.

PubMed

de Castro, John M

2002-01-01

The time of day of meal ingestion, the number of people present at the meal, the subjective state of hunger, and the estimated before-meal contents in the stomach have been established as influences on the amount eaten in a meal and these influences have been shown to be heritable. Because these factors intercorrelate, the calculated heritabilities for some of these variables might result indirectly from their covariation with one of the other heritable variables. The independence of the heritability of the influence of these four factors was investigated with 110 identical and 102 fraternal same-sex and 53 fraternal mixed-sex adult twin pairs who were paid to maintain 7-d food-intake diaries. From the diary reports, the meal sizes were calculated and subjected to multiple regression analysis using the estimated before-meal stomach contents, the reported number of other people present, the subjective hunger ratings, and the time of day of the meal as predictors. Linear structural modeling was applied to the beta-coefficients from the multiple regression to investigate whether the heritability of the influences of these four variables was independent. Significant genetic effects were found for the beta-coefficients for all four variables, indicating that the heritability of their relationship with intake is to some extent independent and heritable. This suggests that influences of multiple factors on intake are influenced by the genes and become part of the total package of genetically determined physiologic, sociocultural, and psychological processes that regulate energy balance.

Heritability of diurnal changes in food intake in free-living humans.

PubMed

de Castro, J M

2001-09-01

The time of day of meal ingestion, the number of people present at the meal, the subjective state of hunger, and the estimated before-meal contents in the stomach have been established as influences on the amount eaten in a meal, and this influence has been shown to be heritable. Because these factors intercorrelate, the possibility that the calculated heritabilities for some of these variables could result indirectly from their convariation with one of the other heritable variables was assessed. The independence of the heritability of the influence of these four factors was investigated with 110 identical and 102 fraternal same-sex and 53 fraternal mixed-sex adult twin pairs who were paid to maintain 7-d food intake diaries. From the diary reports, the meal sizes were calculated and subjected to multiple regression analysis using the estimated before-meal stomach contents, the reported number of other people present, the subjective hunger ratings, and the time of day of the meal as predictors. Linear structural modeling was applied to the beta coefficients from the multiple regression to investigate whether the heritability of the influences of these four variables was independent. Significant genetic effects were found for the beta coefficients for all four variables, indicating that the heritability of their relationship with intake is to some extent heritable. These results suggest that the influences of multiple factors on intake are influenced by the genes and become part of the total package of genetically determined physiologic, sociocultural, and psychological processes that regulate energy balance.

A Computational Fluid Dynamics Study of Swirling Flow Reduction by Using Anti-Vortex Baffle

NASA Technical Reports Server (NTRS)

Yang, H. Q.; West, Jeff; Peugeot, John W.

2017-01-01

OBJECTIVES: To evaluate proposed anti-vortex design in suppressing swirling flow during US burn. APPROACH: Include two major body forces in the analysis a)Vehicle acceleration (all three components); b)Vehicle maneuvers (roll, pitch, and yaw). Perform two drainage analyses of Ares I LOX tank using 6 DOF body forces predicted by GN&C analysis (Guidance Navigation and Control) during vehicle ascent: one with baffle, one without baffle. MODEL: Use Ares I defined geometry. O-Grid for easy fitting of baffle. In this preliminary analysis the holes are sealed. Use whole 360 deg. model with no assumption of symmetry or cyclic boundary conditions. Read in 6DOF data vs time from a file.

Phenomenological study of subsonic turbulent flow over a swept rearward-facing step. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Selby, G. V.

1982-01-01

The phenomenology of turbulent, subsonic flow over a swept, rearward-facing step was studied. Effects of variations in step height, sweep angle, base geometry, and end conditions on the 3-D separated flow were examined. The separated flow was visualized using smoke wire, oil drop, and surface tuft techniques. Measurements include surface pressure, reattachment distance and swirl angle. Results indicate: (1) model/test section coupling affects the structure of the separated flow, but spanwise end conditions do not; (2) the independence principle is evidently valid for sweep angles up to 38 deg; (3) a sweep angle/swirl angle correlation exists; and (4) base modifications can significantly reduce the reattachment distance.

Jupiter Swirling Pearl Storm

NASA Image and Video Library

2017-03-30

This image, taken by the JunoCam imager on NASA's Juno spacecraft, highlights a swirling storm just south of one of the white oval storms on Jupiter. The image was taken on March 27, 2017, at 2:12 a.m. PDT (5:12 a.m. EDT), as the Juno spacecraft performed a close flyby of Jupiter. At the time the image was taken, the spacecraft was about 12,400 miles (20,000 kilometers) from the planet. Citizen scientist Jason Major enhanced the color and contrast in this image, turning the picture into a Jovian work of art. He then cropped it to focus our attention on this beautiful example of Jupiter's spinning storms. https://photojournal.jpl.nasa.gov/catalog/PIA21387

Asynchronous oscillations of rigid rods drive viscous fluid to swirl

NASA Astrophysics Data System (ADS)

Hayashi, Rintaro; Takagi, Daisuke

2017-12-01

We present a minimal system for generating flow at low Reynolds number by oscillating a pair of rigid rods in silicone oil. Experiments show that oscillating them in phase produces no net flow, but a phase difference alone can generate rich flow fields. Tracer particles follow complex trajectory patterns consisting of small orbital movements every cycle and then drifting or swirling in larger regions after many cycles. Observations are consistent with simulations performed using the method of regularized Stokeslets, which reveal complex three-dimensional flow structures emerging from simple oscillatory actuation. Our findings reveal the basic underlying flow structure around oscillatory protrusions such as hairs and legs as commonly featured on living and nonliving bodies.

Relationship of socio-economic factors and parental eating habits with children's food intake in a population-based study in a metropolitan area of Brazil.

PubMed

dos Santos Barroso, Gabriela; Sichieri, Rosely; Salles-Costa, Rosana

2014-01-01

To evaluate the association of sociodemographic factors and parental food consumption with children's food intake. A cross-sectional survey. A population-based study with a representative sample in a metropolitan region of Rio de Janeiro, Brazil. Parents' socio-economic variables, age and education level and children's age were obtained by face-to-face interviews. The parental food intake was assessed using an FFQ and the children's food intake was assessed using two 24 h recalls. Children (n 366) aged 6-30 months and their parents. The hierarchical regression analysis indicated that parents' age was positively associated with the intake of vegetables among children (β = 0·73, 95% CI 0·11, 1·34), while parents' educational level was positively associated with the intake of fats (β = 3·52, 95% CI 0·04, 7·01) and negatively associated with the intake of beans (β = -13·98, 95% CI -27·94, -0·03). The age of the children was positively associated with the intakes of meats and eggs (β = 2·88, 95% CI 1·55, 4·22), sugars (β = 5·08, 95% CI 1·85, 8·30) and coffee (β = 1·77, 95% CI 0·71, 2·84), and negatively associated with the intake of vegetables (β = -2·12, 95% CI -3·20, -1·05). The influence of parental food intake was observed for the food groups of breads, cereals and tubers (β = 0·06, 95% CI 0·003, 0·12), beans (β = 0·11, 95% CI -0·003, 0·22) and fruits (β = 0·10, 95% CI 0·03, 0·16). Unfavourable socio-economic variables were associated with intakes of breads, cereals and tubers, vegetables, fruits, meats, sugars and coffee by children. Parental food intake is associated with children's intake of cereals, beans and fruits independent of socio-economic status.

Protein intakes are associated with reduced length of stay: a comparison between Enhanced Recovery After Surgery (ERAS) and conventional care after elective colorectal surgery.

PubMed

Yeung, Sophia E; Hilkewich, Leslee; Gillis, Chelsia; Heine, John A; Fenton, Tanis R

2017-07-01

Background: Protein can modulate the surgical stress response and postoperative catabolism. Enhanced Recovery After Surgery (ERAS) protocols are evidence-based care bundles that reduce morbidity. Objective: In this study, we compared protein adequacy as well as energy intakes, gut function, clinical outcomes, and how well nutritional variables predict length of hospital stay (LOS) in patients receiving ERAS protocols and conventional care. Design: We conducted a prospective cohort study in adult elective colorectal resection patients after conventional ( n = 46) and ERAS ( n = 69) care. Data collected included preoperative Malnutrition Screening Tool (MST) score, 3-d food records, postoperative nausea, LOS, and complications. Multivariable regression analysis assessed whether low protein intakes and the MST score were predictive of LOS. Results: Total protein intakes were significantly higher in the ERAS group due to the inclusion of oral nutrition supplements (conventional group: 0.33 g · kg -1 · d -1 ; ERAS group: 0.54 g · kg -1 · d -1 ; P < 0.02). This group difference in protein intake was maintained in a multivariable model that controlled for differences between baseline and surgical variables ( P = 0.001). Oral food intake did not differ between the 2 groups. The ERAS group had shorter LOS ( P = 0.049) and fewer total infectious complications ( P = 0.01). Nausea was a predictor of protein intake. Nutrition variables were independent predictors of earlier discharge after potential confounders were controlled for. Each unit increase in preoperative MST score predicted longer LOSs of 2.5 d (95% CI: 1.5, 3.5 d; P < 0.001), and the consumption of ≥60% of protein requirements during the first 3 d of hospitalization was associated with a shorter LOS of 4.4 d (95% CI: -6.8, -2.0 d; P < 0.001). Conclusions: ERAS patients consumed more protein due to the inclusion of oral nutrition supplements. However, total protein intake remained inadequate to meet recommendations. Consumption of ≥60% protein needs after surgery and MST scores were independent predictors of LOS. This trial was registered at clinicaltrials.gov as NCT02940665. © 2017 American Society for Nutrition.

A supersonic fan equipped variable cycle engine for a Mach 2.7 supersonic transport

NASA Technical Reports Server (NTRS)

Tavares, T. S.

1985-01-01

The concept of a variable cycle turbofan engine with an axially supersonic fan stage as powerplant for a Mach 2.7 supersonic transport was evaluated. Quantitative cycle analysis was used to assess the effects of the fan inlet and blading efficiencies on engine performance. Thrust levels predicted by cycle analysis are shown to match the thrust requirements of a representative aircraft. Fan inlet geometry is discussed and it is shown that a fixed geometry conical spike will provide sufficient airflow throughout the operating regime. The supersonic fan considered consists of a single stage comprising a rotor and stator. The concept is similar in principle to a supersonic compressor, but differs by having a stator which removes swirl from the flow without producing a net rise in static pressure. Operating conditions peculiar to the axially supersonic fan are discussed. Geometry of rotor and stator cascades are presented which utilize a supersonic vortex flow distribution. Results of a 2-D CFD flow analysis of these cascades are presented. A simple estimate of passage losses was made using empirical methods.

Dietary intake is independently associated with the maximal capacity for fat oxidation during exercise12

PubMed Central

Eves, Frank F; Glover, Elisa I; Robinson, Scott L; Vernooij, Carlijn A

2017-01-01

Background: Substantial interindividual variability exists in the maximal rate of fat oxidation (MFO) during exercise with potential implications for metabolic health. Although the diet can affect the metabolic response to exercise, the contribution of a self-selected diet to the interindividual variability in the MFO requires further clarification. Objective: We sought to identify whether recent, self-selected dietary intake independently predicts the MFO in healthy men and women. Design: The MFO and maximal oxygen uptake (O2 max) were determined with the use of indirect calorimetry in 305 healthy volunteers [150 men and 155 women; mean ± SD age: 25 ± 6 y; body mass index (BMI; in kg/m2): 23 ± 2]. Dual-energy X-ray absorptiometry was used to assess body composition with the self-reported physical activity level (SRPAL) and dietary intake determined in the 4 d before exercise testing. To minimize potential confounding with typically observed sex-related differences (e.g., body composition), predictor variables were mean-centered by sex. In the analyses, hierarchical multiple linear regressions were used to quantify each variable’s influence on the MFO. Results: The mean absolute MFO was 0.55 ± 0.19 g/min (range: 0.19–1.13 g/min). A total of 44.4% of the interindividual variability in the MFO was explained by the O2 max, sex, and SRPAL with dietary carbohydrate (carbohydrate; negative association with the MFO) and fat intake (positive association) associated with an additional 3.2% of the variance. When expressed relative to fat-free mass (FFM), the MFO was 10.8 ± 3.2 mg · kg FFM−1 · min−1 (range: 3.5–20.7 mg · kg FFM−1 · min−1) with 16.6% of the variability explained by the O2 max, sex, and SRPAL; dietary carbohydrate and fat intakes together explained an additional 2.6% of the variability. Biological sex was an independent determinant of the MFO with women showing a higher MFO [men: 10.3 ± 3.1 mg · kg FFM−1 · min−1 (3.5–19.9 mg · kg FFM−1 · min−1); women: 11.2 ± 3.3 mg · kg FFM−1 · min−1 (4.6–20.7 mg · kg FFM−1 · min−1); P < 0.05]. Conclusion: Considered alongside other robust determinants, dietary carbohydrate and fat intake make modest but independent contributions to the interindividual variability in the capacity to oxidize fat during exercise. This trial was registered at clinicaltrials.gov as NCT02070055. PMID:28251936

Improving the estimation of flavonoid intake for study of health outcomes

USDA-ARS?s Scientific Manuscript database

Imprecision in estimating intakes of non-nutrient bioactive compounds such as flavonoids is a challenge in epidemiologic studies of health outcomes. The sources of this imprecision, using flavonoids as an example, include the variability of bioactive compounds in foods due to differences in growing ...

Internal flow characteristics in scaled pressure-swirl atomizer

NASA Astrophysics Data System (ADS)

Malý, Milan; Sapík, Marcel; Jedelský, Jan; Janáčková, Lada; Jícha, Miroslav; Sláma, Jaroslav; Wigley, Graham

2018-06-01

Pressure-swirl atomizers are used in a wide range of industrial applications, e.g.: combustion, cooling, painting, food processing etc. Their spray characteristics are closely linked to the internal flow which predetermines the parameters of the liquid sheet formed at the discharge orifice. To achieve a better understanding of the spray formation process, the internal flow was characterised using Laser Doppler Anemometry (LDA) and high-speed imaging in a transparent model made of cast PMMA (Poly(methyl methacrylate)). The design of the transparent atomizer was derived from a pressure-swirl atomizer as used in a small gas turbine. Due to the small dimensions, it was manufactured in a scale of 10:1. It has modular concept and consists of three parts which were ground, polished and bolted together. The original kerosene-type jet A-1 fuel had to be replaced due to the necessity of a refractive index match. The new working liquid should also be colourless, non-aggressive to the PMMA and have the appropriate viscosity to achieve the same Reynolds number as in the original atomizer. Several liquids were chosen and tested to satisfy these requirements. P-Cymene was chosen as the suitable working liquid. The internal flow characteristics were consequently examined by LDA and high-speed camera using p-Cymene and Kerosene-type jet A-1 in comparative manner.

Turbomachine Sealing and Secondary Flows. Part 2; Review of Rotordynamics Issues in Inherently Unsteady Flow Systems With Small Clearances

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Tam, L. T.; Muszynska, A.

2004-01-01

Today's computational methods enable the determination of forces in complex systems, but without field validation data, or feedback, there is a high risk of failure when the design envelope is challenged. The data of Childs and Bently and field data reported in NASA Conference Proceedings serve as sources of design information for the development of these computational codes. Over time all turbomachines degrade and instabilities often develop, requiring responsible, accurate, turbomachine diagnostics with proper decisions to prevent failures. Tam et al. (numerical) and Bently and Muszynska (analytical) models corroborate and implicate that destabilizing factors are related through increases in the fluid-force average circumferential velocity. The stability threshold can be controlled by external swirl and swirl brakes and increases in radial fluid film stiffness (e.g., hydrostatic and ambient pressures) to enhance rotor stability. Also cited are drum rotor self-excited oscillations, where the classic fix is to add a split or severed damper ring or cylindrical damper drum, and the Benkert-Wachter work that engendered swirl brake concepts. For a smooth-operating, reliable, long-lived machine, designers must pay very close attention to sealing dynamics and diagnostic methods. Correcting the seals enabled the space shuttle main engine high-pressure fuel turbopump (SSME HPFTP) to operate successfully.

Alignment of cellular motility forces with tissue flow as a mechanism for efficient wound healing

PubMed Central

Basan, Markus; Elgeti, Jens; Hannezo, Edouard; Rappel, Wouter-Jan; Levine, Herbert

2013-01-01

Recent experiments have shown that spreading epithelial sheets exhibit a long-range coordination of motility forces that leads to a buildup of tension in the tissue, which may enhance cell division and the speed of wound healing. Furthermore, the edges of these epithelial sheets commonly show finger-like protrusions whereas the bulk often displays spontaneous swirls of motile cells. To explain these experimental observations, we propose a simple flocking-type mechanism, in which cells tend to align their motility forces with their velocity. Implementing this idea in a mechanical tissue simulation, the proposed model gives rise to efficient spreading and can explain the experimentally observed long-range alignment of motility forces in highly disordered patterns, as well as the buildup of tensile stress throughout the tissue. Our model also qualitatively reproduces the dependence of swirl size and swirl velocity on cell density reported in experiments and exhibits an undulation instability at the edge of the spreading tissue commonly observed in vivo. Finally, we study the dependence of colony spreading speed on important physical and biological parameters and derive simple scaling relations that show that coordination of motility forces leads to an improvement of the wound healing process for realistic tissue parameters. PMID:23345440

A novel approach of magnetorheological abrasive fluid finishing with swirling-assisted inlet flow

NASA Astrophysics Data System (ADS)

Kheradmand, Saeid; Esmailian, Mojtaba; Fatahy, A.

Abrasive flow machining has been the pioneer of new finishing processes. Rotating workpiece and imposing a magnetic field using magnetorheological working medium are some assisting manipulations to improve surface finishing, because they can increase the forces on the workpiece surface. Similarly, swirling the inlet flow using stationary swirler vanes, as a novel idea, may also increase forces on the surface, and then raise the material removal, with a lower expense and energy consumption compared with the case of workpiece rotation. Thus, in this paper, surface roughness improvement is studied in a pipe with rotating inlet flow of a magnetorheological finishing medium under imposing a magnetic field. The results are compared with the case of rotating workpiece, using 3D numerical simulation. The governing hydrodynamic parameters are investigated in both cases to monitor the flow variations. It is shown that surface roughness is improved by rotating inlet flow. However, it is found that finishing in the entrance length of swirling-assisted inlet flow can be so economical for short length workpieces, compared with the case of rotating workpiece, with very near Ra values. By comparison of the numerical results and published experimental data, current study also shows the ability of the numerical simulation, as an inexpensive and efficient tool, to predict the surface roughness changes in finishing processes.

Fabrication and characterization of a micromachined swirl-shaped ionic polymer metal composite actuator with electrodes exhibiting asymmetric resistance.

PubMed

Feng, Guo-Hua; Liu, Kim-Min

2014-05-12

This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation.

Optimization of Simplex Atomizer Inlet Port Configuration through Computational Fluid Dynamics and Experimental Study for Aero-Gas Turbine Applications

NASA Astrophysics Data System (ADS)

Marudhappan, Raja; Chandrasekhar, Udayagiri; Hemachandra Reddy, Koni

2017-10-01

The design of plain orifice simplex atomizer for use in the annular combustion system of 1100 kW turbo shaft engine is optimized. The discrete flow field of jet fuel inside the swirl chamber of the atomizer and up to 1.0 mm downstream of the atomizer exit are simulated using commercial Computational Fluid Dynamics (CFD) software. The Euler-Euler multiphase model is used to solve two sets of momentum equations for liquid and gaseous phases and the volume fraction of each phase is tracked throughout the computational domain. The atomizer design is optimized after performing several 2D axis symmetric analyses with swirl and the optimized inlet port design parameters are used for 3D simulation. The Volume Of Fluid (VOF) multiphase model is used in the simulation. The orifice exit diameter is 0.6 mm. The atomizer is fabricated with the optimized geometric parameters. The performance of the atomizer is tested in the laboratory. The experimental observations are compared with the results obtained from 2D and 3D CFD simulations. The simulated velocity components, pressure field, streamlines and air core dynamics along the atomizer axis are compared to previous research works and found satisfactory. The work has led to a novel approach in the design of pressure swirl atomizer.

Flow Structure Comparison for Two 7-Point LDI Configurations

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Tacina, Kathleen M.

2017-01-01

This paper presents a comparison primarily of the cold flow 2-D velocity profiles; and describes flame tube combusting flow operability for a 7-point Lean Direct Injector (LDI). This circular LDI array consists of a center element surrounded by six outer elements spaced 60 degrees apart; the spacing between all adjacent elements is the same. Each element consists of a simplex atomizer that injects at the throat of a converging-diverging venturi, and an axial swirler upstream of the venturi throat to generate swirl. The two configurations were: 1) one which consists of all 60 deg co-swirling axial air swirlers, and; 2) one configuration which uses a 60 deg swirler in the center, surrounded by counter-swirling 45 deg swirlers. Testing was done at 5- bar and at an inlet temperature of 700K. Two air reference velocities were considered in the cold flow measurements. The 2D velocity profiles were determined using particle image velocimetry. Results indicate the configuration using all 60 deg swirlers generates a field that moderates to a more uniform distribution at a shorter distance downstream and is more easily operable than the second configuration, which produces recirculation regions at the edges of the outer 45 deg swirlers, and results in a more stratified velocity field at any given axial location.

Eigenmodes of Ducted Flows With Radially-Dependent Axial and Swirl Velocity Components

NASA Technical Reports Server (NTRS)

Kousen, Kenneth A.

1999-01-01

This report characterizes the sets of small disturbances possible in cylindrical and annular ducts with mean flow whose axial and tangential components vary arbitrarily with radius. The linearized equations of motion are presented and discussed, and then exponential forms for the axial, circumferential, and time dependencies of any unsteady disturbances are assumed. The resultant equations form a generalized eigenvalue problem, the solution of which yields the axial wavenumbers and radial mode shapes of the unsteady disturbances. Two numerical discretizations are applied to the system of equations: (1) a spectral collocation technique based on Chebyshev polynomial expansions on the Gauss-Lobatto points, and (2) second and fourth order finite differences on uniform grids. The discretized equations are solved using a standard eigensystem package employing the QR algorithm. The eigenvalues fall into two primary categories: a discrete set (analogous to the acoustic modes found in uniform mean flows) and a continuous band (analogous to convected disturbances in uniform mean flows) where the phase velocities of the disturbances correspond to the local mean flow velocities. Sample mode shapes and eigensystem distributions are presented for both sheared axial and swirling flows. The physics of swirling flows is examined with reference to hydrodynamic stability and completeness of the eigensystem expansions. The effect of assuming exponential dependence in the axial direction is discussed.

Sediment morpho-dynamics induced by a swirl-flow: an experimental study

NASA Astrophysics Data System (ADS)

Gonzalez-Vera, Alfredo; Duran-Matute, Matias; van Heijst, Gertjan

2016-11-01

This research focuses on a detailed experimental study of the effect of a swirl-flow over a sediment bed in a cylindrical domain. Experiments were performed in a water-filled cylindrical rotating tank with a bottom layer of translucent polystyrene particles acting as a sediment bed. The experiments started by slowly spinning the tank up until the fluid had reached a solid-body rotation at a selected rotation speed (Ωi). Once this state was reached, a swirl-flow was generated by spinning-down the system to a lower rotation rate (Ωf). Under the flow's influence, particles from the bed were displaced, which changed the bed morphology, and under certain conditions, pattern formation was observed. Changes in the bed height distribution were measured by utilizing a Light Attenuation Technique (LAT). For this purpose, the particle layer was illuminated from below. Images of the transmitted light distribution provided quantitative information about the local thickness of the sediment bed. The experiments revealed a few characteristic regimes corresponding to sediment displacement, pattern formation and the occurrence of particle pick-up. Such regimes depend on both the Reynolds (Re) and Rossby (Ro) numbers. This research is funded by CONACYT (Mexico) through the Ph.D. Grant (383903) and NWO (the Netherlands) through the VENI Grant (863.13.022).

Effect of the fuel bias distribution in the primary air nozzle on the slagging near a swirl coal burner throat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lingyan Zeng; Zhengqi Li; Hong Cui

2009-09-15

Three-dimensional numerical simulations of slagging characteristics near the burner throat region were carried out for swirl coal combustion burners used in a 1025 tons/h boiler. The gas/particle two-phase numerical simulation results and the data measured by a particle-dynamics anemometer (PDA) show that the numeration model was reasonable. For the centrally fuel-rich swirl coal combustion burner, the coal particles move in the following way. The particles first flow into furnace with the primary air from the burner throat. After traversing a certain distance, they move back to the burner throat and then toward the furnace again. Thus, particle trajectories are extended.more » For the case with equal air mass fluxes in the inner and outer primary air/coal mixtures, as the ratio of the coal mass flux in the inner primary air/coal mixture to the total coal mass flux increased from 40 (the reference condition) to 50%, 50 to 70%, and 70 to 100%, the maximum number density declined by 22, 11, and 4%, respectively, relative to the reference condition. In addition, the sticking particle ratio declined by 13, 14, and 8%, respectively, compared to the reference condition. 22 refs., 12 figs., 3 tabs.« less

Effect of Boundary Conditions on Numerically Simulated Tornado-like Vortices.

NASA Astrophysics Data System (ADS)

Smith, David R.

1987-02-01

The boundary conditions for Rotunno's numerical model which simulates tornado-like vortices are examined. In particular, the lateral boundary condition for tangential velocity and the upper boundary condition for radial and tangential velocities are considered to determine if they have any significant impact on vortex development.The choice of the lateral boundary condition did not appear to have any real effect on the development of the vortex over the range of swirl ratios studied (0.87-2.61).The upper boundary conditions attempt to simulate both the presence and absence of the flow-straightening baffle. The boundary condition corresponding to the baffle in place produced a distinct boundary layer in the u and v field and very strong upflow and downflow within the vortex core. When this condition is removed, there is both radial and tangential motion throughout the domain and a reduction of the vertical velocity. At small swirl ratio (S = 0.87) this boundary condition has a profound impact on the narrow vortex, producing changes in the pressure field that intensifies the vortex. At higher swirl ratio the vortex is apparently broad enough to better adjust to the changes of the upper boundary condition and, thus, experiences little change in the development of the vortex.

Design and Study of a LOX/GH2 Throttleable Swirl Injector for Rocket Applications

NASA Technical Reports Server (NTRS)

Greene, Christopher; Woodward, Roger; Pal, Sibtosh; Santoro, Robert

2002-01-01

A LOX/GH2 swirl injector was designed for a 10:1 propellant throttling range. To accomplish this, a dual LOX manifold was used feeding a single common vortex chamber of the swirl element. Hot-fire experiments were conducted for rocket chamber pressures from 80 to 800 psia at a mixture ratio of nominally 6.0 using steady flow, single-point-per-firing cases as well as dynamic throttling conditions. Low frequency (mean) and high frequency (fluctuating) pressure transducer data, flow meter measurements, and Raman spectroscopy images for mixing information were obtained. The injector design, experimental setup, low frequency pressure data, and injector performance analysis are presented. C* efficiency was very high (approx. 100%) at the middle of the throttleable range with somewhat lower performance at the high and low ends. From the analysis of discreet steady state operating conditions, injector pressure drop was slightly higher than predicted with an inviscid analysis, but otherwise agreed well across the design throttling range. Dynamic throttling of this injector was attempted with marginal success due to the immaturity of the throttling control system. Although the targeted mixture ratio of 6.0 was not maintained throughout the dynamic throttling profile, the injector behaved well over the wide range of conditions.

Fabrication and Characterization of a Micromachined Swirl-Shaped Ionic Polymer Metal Composite Actuator with Electrodes Exhibiting Asymmetric Resistance

PubMed Central

Feng, Guo-Hua; Liu, Kim-Min

2014-01-01

This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation. PMID:24824370

NOx results from two combustors tested on medium BTU coal gas

NASA Technical Reports Server (NTRS)

Sherlock, T. P.; Carl, D. E.; Vermes, G.; Schwab, J.; Notardonato, J. J.

1982-01-01

The results of tests of two combustor configurations using coal gas from a 25 ton/day fluidized bed coal gasifier are reported. The trials were run with a ceramic-lined, staged rich/lean burner and an integral, all metal multiannular swirl burner (MASB) using a range of temperatures and pressures representative of industrial turbine inlet conditions. A lean mixture was examined at 104, 197, and 254 Btu/Scf, yielding NO(x) emissions of 5, 20, and 70 ppmv, respectively. The MASB was employed only with a gas rated at 220-270 Btu/Scf, producing 80 ppmv NO(x) at rated engine conditions. The results are concluded to be transferrable to current machines. Further tests on the effects of gas composition, the scaling of combustors to utility size, and the development of improved wall cooling techniques and variable geometry are indicated.

Advanced technology for reducing aircraft engine pollution

NASA Technical Reports Server (NTRS)

Jones, R. E.

1973-01-01

Combustor research programs are described whose purpose is to demonstrate significantly lower exhaust emission levels. The proposed EPA regulations covering the allowable levels of emissions will require a major technological effort if these levels are to be met by 1979. Pollution reduction technology is being pursued by NASA through a combination of in-house research, contracted progams, and university grants. In-house research with the swirl-can modular combustor and the double-annular combustor has demonstrated significant reduction in the level of NO(x) emissions. The work is continuing in an attempt to further reduce these levels by improvements in module design and in air-fuel scheduling. Research on the reduction of idle emissions has included the conversion of conventional duplex fuel nozzles to air-assisted nozzles and exploration of the potential improvements possible with fuel staging and variable combustor geometry.

Unsteady flowfield in an integrated rocket ramjet engine and combustion dynamics of a gas turbine swirl-stabilized injector

NASA Astrophysics Data System (ADS)

Sung, Hong-Gye

This research focuses on the time-accurate simulation and analysis of the unsteady flowfield in an integrated rocket-ramjet engine (IRR) and combustion dynamics of a swirl-stabilized gas turbine engine. The primary objectives are: (1) to establish a unified computational framework for studying unsteady flow and flame dynamics in ramjet propulsion systems and gas turbine combustion chambers, and (2) to investigate the parameters and mechanisms responsible for driving flow oscillations. The first part of the thesis deals with a complete axi-symmetric IRR engine. The domain of concern includes a supersonic inlet diffuser, a combustion chamber, and an exhaust nozzle. This study focused on the physical mechanism of the interaction between the oscillatory terminal shock in the inlet diffuser and the flame in the combustion chamber. In addition, the flow and ignition transitions from the booster to the sustainer phase were analyzed comprehensively. Even though the coupling between the inlet dynamics and the unsteady motions of flame shows that they are closely correlated, fortunately, those couplings are out of phase with a phase lag of 90 degrees, which compensates for the amplification of the pressure fluctuation in the inlet. The second part of the thesis treats the combustion dynamics of a lean-premixed gas turbine swirl injector. A three-dimensional computation method utilizing the message passing interface (MPI) Parallel architecture and large-eddy-simulation technique was applied. Vortex breakdown in the swirling flow is clearly visualized and explained on theoretical bases. The unsteady turbulent flame dynamics are carefully simulated so that the flow motion can be characterized in detail. It was observed that some fuel lumps escape from the primary combustion zone, and move downstream and consequently produce hot spots and large vortical structures in the azimuthal direction. The correlation between pressure oscillation and unsteady heat release is examined by both the spatial and temporal Rayleigh parameters. In addition, basis modes of the unsteady turbulent flame are characterized using proper orthogonal decomposition (POD) analysis.

Large Eddy Simulation Modeling of Flashback and Flame Stabilization in Hydrogen-Rich Gas Turbines Using a Hierarchical Validation Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clemens, Noel

This project was a combined computational and experimental effort to improve predictive capability for boundary layer flashback of premixed swirl flames relevant to gas-turbine power plants operating with high-hydrogen-content fuels. During the course of this project, significant progress in modeling was made on four major fronts: 1) use of direct numerical simulation of turbulent flames to understand the coupling between the flame and the turbulent boundary layer; 2) improved modeling capability for flame propagation in stratified pre-mixtures; 3) improved portability of computer codes using the OpenFOAM platform to facilitate transfer to industry and other researchers; and 4) application of LESmore » to flashback in swirl combustors, and a detailed assessment of its capabilities and limitations for predictive purposes. A major component of the project was an experimental program that focused on developing a rich experimental database of boundary layer flashback in swirl flames. Both methane and high-hydrogen fuels, including effects of elevated pressure (1 to 5 atm), were explored. For this project, a new model swirl combustor was developed. Kilohertz-rate stereoscopic PIV and chemiluminescence imaging were used to investigate the flame propagation dynamics. In addition to the planar measurements, a technique capable of detecting the instantaneous, time-resolved 3D flame front topography was developed and applied successfully to investigate the flow-flame interaction. The UT measurements and legacy data were used in a hierarchical validation approach where flows with increasingly complex physics were used for validation. First component models were validated with DNS and literature data in simplified configurations, and this was followed by validation with the UT 1-atm flashback cases, and then the UT high-pressure flashback cases. The new models and portable code represent a major improvement over what was available before this project was initiated.« less

Turbulence and turbulent drag reduction in swirling flow: Inertial versus viscous forcing

NASA Astrophysics Data System (ADS)

Burnishev, Yuri; Steinberg, Victor

2015-08-01

We report unexpected results of a drastic difference in the transition to fully developed turbulent and turbulent drag reduction (TDR) regimes and in their properties in a von Karman swirling flow with counter-rotating disks of water-based polymer solutions for viscous (by smooth disks) as well as inertial (by bladed disks) forcing and by tracking just torque Γ (t ) and pressure p (t ) . For the viscous forcing, just a single TDR regime is found with the transition values of the Reynolds number (Re) Recturb=RecTDR≃(4.8 ±0.2 ) ×105 independent of ϕ , whereas for the inertial forcing two turbulent regimes are revealed. The first transition is to fully developed turbulence, and the second one is to the TDR regime with both Recturb and RecTDR depending on polymer concentration ϕ . Both regimes differ by the values of Cf and Cp, by the scaling exponents of the fundamental turbulent characteristics, by the nonmonotonic dependencies of skewness and flatness of the pressure PDFs on Re, and by the different frequency power spectra of p with the different dependencies of the main vortex peak frequency in the p power spectra on ϕ and Re. Thus our experimental results show the transition to the TDR regime in a von Karman swirling flow for the viscous and inertial forcings in a sharp contrast to the recent experiments [Phys. Fluids 10, 426 (1998), 10.1063/1.869532; Phys. Rev. E 47, R28(R) (1993), 10.1103/PhysRevE.47.R28; and J. Phys.: Condens. Matter 17, S1195 (2005), 10.1088/0953-8984/17/14/008] where the transition to TDR is observed in the same swirling flow with counter-rotating disks only for the viscous forcing. The latter result has led its authors to the wrong conclusion that TDR is a solely boundary effect contrary to the inertial forcing associated with the bulk effect, and this conception is currently rather widely accepted in literature.

Turbulence and turbulent drag reduction in swirling flow: Inertial versus viscous forcing.

PubMed

Burnishev, Yuri; Steinberg, Victor

2015-08-01

We report unexpected results of a drastic difference in the transition to fully developed turbulent and turbulent drag reduction (TDR) regimes and in their properties in a von Karman swirling flow with counter-rotating disks of water-based polymer solutions for viscous (by smooth disks) as well as inertial (by bladed disks) forcing and by tracking just torque Γ(t) and pressure p(t) . For the viscous forcing, just a single TDR regime is found with the transition values of the Reynolds number (Re) Re turb c =Re TDR c ≃(4.8±0.2)×10(5) independent of ϕ , whereas for the inertial forcing two turbulent regimes are revealed. The first transition is to fully developed turbulence, and the second one is to the TDR regime with both Re turb c and Re TDR c depending on polymer concentration ϕ . Both regimes differ by the values of C f and C p , by the scaling exponents of the fundamental turbulent characteristics, by the nonmonotonic dependencies of skewness and flatness of the pressure PDFs on Re, and by the different frequency power spectra of p with the different dependencies of the main vortex peak frequency in the p power spectra on ϕ and Re. Thus our experimental results show the transition to the TDR regime in a von Karman swirling flow for the viscous and inertial forcings in a sharp contrast to the recent experiments [Phys. Fluids 10, 426 (1998); Phys. Rev. E 47, R28(R) (1993); and J. Phys.: Condens. Matter 17, S1195 (2005)] where the transition to TDR is observed in the same swirling flow with counter-rotating disks only for the viscous forcing. The latter result has led its authors to the wrong conclusion that TDR is a solely boundary effect contrary to the inertial forcing associated with the bulk effect, and this conception is currently rather widely accepted in literature.

Evolution and transition mechanisms of internal swirling flows with tangential entry

NASA Astrophysics Data System (ADS)

Wang, Yanxing; Wang, Xingjian; Yang, Vigor

2018-01-01

The characteristics and transition mechanisms of different states of swirling flow in a cylindrical chamber have been numerically investigated using the Galerkin finite element method. The effects of the Reynolds number and swirl level were examined, and a unified theory connecting different flow states was established. The development of each flow state is considered as a result of the interaction and competition between basic mechanisms: (1) the centrifugal effect, which drives an axisymmetric central recirculation zone (CRZ); (2) flow instabilities, which develop at the free shear layer and the central solid-body rotating flow; (3) the bouncing and restoring effects of the injected flow, which facilitate the convergence of flow on the centerline and the formation of bubble-type vortex breakdown; and (4) the damping effect of the end-induced flow, which suppresses the development of the instability waves. The results show that the CRZ, together with the free shear layer on its surface, composes the basic structure of swirling flow. The development of instability waves produces a number of discrete vortex cores enclosing the CRZ. The azimuthal wave number is primarily determined by the injection angle. Generally, the wave number is smaller at a higher injection angle, due to the reduction of the perimeter of the free shear layer. At the same time, the increase in the Reynolds number facilitates the growth of the wave number. The end-induced flow tends to reduce the wave number near the head end and causes a change in wave number from the head end to the downstream region. Spiral-type vortex breakdown can be considered as a limiting case at a high injection angle, with a wave number equal to 0 near the head end and equal to 1 downstream. At lower Reynolds numbers, the bouncing and restoring effect of the injected flow generates bubble-type vortex breakdown.

Co-firing straw with coal in a swirl-stabilized dual-feed burner: modelling and experimental validation.

PubMed

Yin, Chungen; Kaer, Søren K; Rosendahl, Lasse; Hvid, Søren L

2010-06-01

This paper presents a comprehensive computational fluid dynamics (CFD) modelling study of co-firing wheat straw with coal in a 150kW swirl-stabilized dual-feed burner flow reactor, in which the pulverized straw particles (mean diameter of 451microm) and coal particles (mean diameter of 110.4microm) are independently fed into the burner through two concentric injection tubes, i.e., the centre and annular tubes, respectively. Multiple simulations are performed, using three meshes, two global reaction mechanisms for homogeneous combustion, two turbulent combustion models, and two models for fuel particle conversion. It is found that for pulverized biomass particles of a few hundred microns in diameter the intra-particle heat and mass transfer is a secondary issue at most in their conversion, and the global four-step mechanism of Jones and Lindstedt may be better used in modelling volatiles combustion. The baseline CFD models show a good agreement with the measured maps of main species in the reactor. The straw particles, less affected by the swirling secondary air jet due to the large fuel/air jet momentum and large particle response time, travels in a nearly straight line and penetrate through the oxygen-lean core zone; whilst the coal particles are significantly affected by secondary air jet and swirled into the oxygen-rich outer radius with increased residence time (in average, 8.1s for coal particles vs. 5.2s for straw particles in the 3m high reactor). Therefore, a remarkable difference in the overall burnout of the two fuels is predicted: about 93% for coal char vs. 73% for straw char. As the conclusion, a reliable modelling methodology for pulverized biomass/coal co-firing and some useful co-firing design considerations are suggested. Copyright 2010 Elsevier Ltd. All rights reserved.

Photometric Characteristics of Lunar Terrains

NASA Astrophysics Data System (ADS)

Sato, Hiroyuki; Hapke, Bruce W.; Denevi, Brett W.; Robinson, Mark

2016-10-01

The photometric properties of the lunar depend on albedo, surface roughness, porosity, and the internal/external structure of particles. Hapke parameter maps derived using a bidirectional reflectance model [Hapke, 2012] from Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) images demonstrated the spatial and spectral variation of the photometric properties of the Moon [Sato et al., 2014]. Using the same methodology, here we present the photometric characteristics of typical lunar terrains, which were not systematically analyzed in the previous study.We selected five representative terrain types: mare, highland, swirls, and two Copernican (fresh) crater ejecta (one mare and one highlands example). As for the datasets, we used ~39 months of WAC repeated observations, and for each image pixel, we computed latitude, longitude, incidence, emission, and phase angles using the WAC GLD100 stereo DTM [Scholten et al., 2012]. To obtain similar phase and incidence angle ranges, all sampling sites are near the equator and in the vicinity of Reiner Gamma. Three free Hapke parameters (single scattering albedo: w, HG2 phase function parameter: c, and angular width of SHOE: hs) were then calculated for the seven bands (321-689 nm). The remaining parameters were fixed by simplifying the model [Sato et al., 2014].The highlands, highland ejecta, and swirl (Reiner Gamma) showed clearly higher w than the mare and mare ejecta. The derived c values were lower (less backscattering) for the swirl and higher (more backscattering) for the highlands (and ejecta) relative to the other sites. Forward scattering materials such as unconsolidated transparent crystalline materials might be relatively enriched in the swirl. In the highlands, anorthositic agglutinates with dense internal scattering could be responsible for the strong backscattering. The mare and mare ejecta showed continuously decreasing c from UV to visible wavelengths. This might be caused by the FeO-rich pyroxene and glass in the mare becoming more translucent at longer wavelengths.

Detection of Respiratory Viruses in Sputum from Adults by Use of Automated Multiplex PCR

PubMed Central

Walsh, Edward E.; Formica, Maria A.; Falsey, Ann R.

2014-01-01

Respiratory tract infections (RTI) frequently cause hospital admissions among adults. Diagnostic viral reverse transcriptase PCR (RT-PCR) of nose and throat swabs (NTS) is useful for patient care by informing antiviral use and appropriate isolation. However, automated RT-PCR systems are not amenable to utilizing sputum due to its viscosity. We evaluated a simple method of processing sputum samples in a fully automated respiratory viral panel RT-PCR assay (FilmArray). Archived sputum and NTS samples collected in 2008-2012 from hospitalized adults with RTI were evaluated. A subset of sputum samples positive for 10 common viruses by a uniplex RT-PCR was selected. A sterile cotton-tip swab was dunked in sputum, swirled in 700 μL of sterile water (dunk and swirl method) and tested by the FilmArray assay. Quantitative RT-PCR was performed on “dunked” sputum and NTS samples for influenza A (Flu A), respiratory syncytial virus (RSV), coronavirus OC43 (OC43), and human metapneumovirus (HMPV). Viruses were identified in 31% of 965 illnesses using a uniplex RT-PCR. The sputum sample was the only sample positive for 105 subjects, including 35% (22/64) of influenza cases and significantly increased the diagnostic yield of NTS alone (302/965 [31%] versus 197/965 [20%]; P = 0.0001). Of 108 sputum samples evaluated by the FilmArray assay using the dunk and swirl method, 99 (92%) were positive. Quantitative RT-PCR revealed higher mean viral loads in dunked sputum samples compared to NTS samples for Flu A, RSV, and HMPV (P = 0.0001, P = 0.006, and P = 0.011, respectively). The dunk and swirl method is a simple and practical method for reliably processing sputum samples in a fully automated PCR system. The higher viral loads in sputa may increase detection over NTS testing alone. PMID:25056335

Simulating the Reiner Gamma Lunar Swirl: Solar Wind Standoff Works!

NASA Astrophysics Data System (ADS)

Deca, Jan; Divin, Andrey; Lue, Charles; Ahmadi, Tara; Horányi, Mihály

2017-04-01

Discovered by early astronomers during the Renaissance, the Reiner Gamma formation is a prominent lunar surface feature. Observations have shown that the tadpole-shaped albedo marking, or swirl, is co-located with one of the strongest crustal magnetic anomalies on the Moon. The region therefore presents an ideal test case to constrain the kinetic solar wind interaction with lunar magnetic anomalies and its possible consequences for lunar swirl formation. All known swirls have been associated with magnetic anomalies, but the opposite does not hold. The evolutionary scenario of the lunar albedo markings has been under debate since the Apollo era. By coupling fully kinetic simulations with a surface vector mapping model based on Kaguya and Lunar Prospector magnetic field measurements, we show that solar wind standoff is the dominant process to have formed the lunar swirls. It is an ion-electron kinetic interaction mechanism that locally prevents weathering by solar wind ions and the subsequent formation of nanophase iron. The correlation between the surface weathering process and the surface reflectance is optimal when evaluating the proton energy flux, rather than the proton density or number flux. This is an important result to characterise the primary process for surface darkening. In addition, the simulated proton reflection rate is for the first time directly compared with in-orbit flux measurements from the SARA:SWIM ion sensor onboard the Chandrayaan-1 spacecraft. The agreement is found excellent. Understanding the relation between the lunar surface albedo features and the co-located magnetic anomaly is essential for our interpretation of the Moon's geological history, space weathering, and to evaluate future lunar exploration opportunities. This work was supported in part by NASA's Solar System Exploration Research Virtual Institute (SSERVI): Institute for Modeling Plasmas, Atmosphere, and Cosmic Dust (IMPACT). The work by C.L. was supported by NASA grant NNX15AP89G. Resources were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center. Part of this work was inspired by discussions within International Team 336: "Plasma Surface Interactions with Airless Bodies in Space and the Laboratory" at the International Space Science Institute, Bern, Switzerland. The LRO-WAC data are publicly available from the NASA PDS Imaging Node. The Wind/MFI and Wind/SWE data used in this study are available via the NASA National Space Science Data Center, Space Physics Data Facility, and the MIT Space Plasma Group. The Chandrayaan-1/SARA data are available via the Indian Space Science Data Center.

Eating behavior: lessons from the real world of humans.

PubMed

de Castro, J M

2000-10-01

Food intake by normal humans has been investigated both in the laboratory and under free-living conditions in the natural environment. For measurement of real-world intake, the diet-diary technique is imperfect and tends to underestimate actual intakes but it appears to be sensitive, can detect subtle influences on eating behavior, and produces reliable and valid measures. Research studies in the real world show the multivariate richness of the natural environment, which allows investigation of the complexities of intake regulation, and even causation can be investigated. Real-world research can overcome some of the weaknesses of laboratory studies, where constraints on eating are often removed or missing, facilitatory influences on eating are often controlled or eliminated, the importance of variables can be overestimated, and important influences can be missed because of the short durations of the studies. Real-world studies have shown a wide array of physiologic, psychological, and social variables that can have potent and immediate effects on intake. Compensatory mechanisms, including some that operate with a 2- to 3-d delay, adjust for prior excesses. Heredity affects all aspect of food-intake regulation, from the determination of body size to the subtleties of the individual preferences and social proclivities and the extent to which environmental factors affect the individual. Hence, real-world research teaches valuable lessons, and much more is needed to complement laboratory studies.

Tryptophan Intake in the US Adult Population Is Not Related to Liver or Kidney Function but Is Associated with Depression and Sleep Outcomes.

PubMed

Lieberman, Harris R; Agarwal, Sanjiv; Fulgoni, Victor L

2016-12-01

Tryptophan is an indispensable amino acid and is a precursor of the neurotransmitter serotonin. Tryptophan metabolites, such as serotonin and melatonin, are thought to participate in the regulation of mood and sleep and tryptophan is used to treat insomnia, sleep apnea, and depression. This study examined the intake of tryptophan and its associations with biochemical, behavioral, sleep, and health and safety outcomes in adults in a secondary analysis of a large, publicly available database of the US population. Data from the NHANES 2001-2012 (n = 29,687) were used to determine daily intakes of tryptophan and its associations with biochemical markers of health- and safety-related outcomes, self-reported depression, and sleep-related variables. Data were adjusted for demographic factors and protein intake. Linear trends were computed across deciles of intake for each outcome variable, and P-trends were determined. The usual tryptophan intake by US adults was 826 mg/d, severalfold higher than the Estimated Average Requirement for adults of 4 mg/(kg ⋅ d) (∼280 mg/d for a 70-kg adult). Most health- and safety-related biochemical markers of liver function, kidney function, and carbohydrate metabolism were not significantly (P-trend > 0.05) associated with deciles of tryptophan intake and were well within normal ranges, even for individuals in the 99th percentile of intake. Usual intake deciles of tryptophan were inversely associated with self-reported depression measured by the Patient Health Questionnaire raw score (0-27; P-trend < 0.01) and calculated level (1 = no depression, 5 = severe depression; P-trend < 0.01) and were positively associated with self-reported sleep duration (P-trend = 0.02). Tryptophan intake was not related to most markers of liver function, kidney function or carbohydrate metabolism. Levels of tryptophan intake in the US population appear to be safe as shown by the absence of abnormal laboratory findings. Tryptophan intake was inversely associated with self-reported level of depression and positively associated with sleep duration. © 2016 American Society for Nutrition.

Relationship of 6-n-propylthiouracil taste intensity and chili pepper use with body mass index, energy intake, and fat intake within an ethnically diverse population.

PubMed

Choi, Sung Eun; Chan, Jacqueline

2015-03-01

One of the weight-loss strategies that has attracted attention is the use of spicy foods. It has been suggested that spicy food preference is related to a genetically predetermined sensitivity to the bitter compound 6-n-propylthiouracil (PROP). Our aim was to examine the relationship of PROP taste intensity and hot chili pepper use with body mass index (BMI), energy intake, and fat intake. This study utilized a cross-sectional design. The sample included 350 subjects (154 male, 196 female) ages 18 to 55 years living in the New York City area. BMI was calculated by measuring weight and height, and the sensitivity to PROP was evaluated using the PROP filter paper method. Subjects also rated the frequency of usage and preference for hot chili pepper using a chili pepper questionnaire. Their daily energy and fat intake were assessed using a food frequency questionnaire. An independent sample t-test compared subject characteristics between groups based on sex, PROP status, and hot chili pepper user status for the continuous variables, and the χ(2) test was used for categorical variables. One-way analysis variance examined the differences in subject characteristics across four ethnicities. To predict BMI, energy intake, and fat intake, multiple linear regression models were fit with the covariates of age, sex, ethnicity, chili pepper score, and PROP mean. The values for BMI, energy intake, and fat intake of PROP tasters were significantly lower than those of PROP nontasters (P=0.03, P<0.001, and P<0.001, respectively). The energy intake of chili pepper nonusers was significantly lower than that of chili pepper users (P=0.02), while there was no significant difference in fat intake between chili pepper users and nonusers. This study suggests that PROP taste sensitivity contributes more to the prediction of energy and fat intake than chili pepper use. Copyright © 2015 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Acoustic response of vortex breakdown modes in a coaxial isothermal unconfined swirling jet

NASA Astrophysics Data System (ADS)

Santhosh, R.; Basu, Saptarshi

2015-03-01

The present experimental work is concerned with the study of amplitude dependent acoustic response of an isothermal coaxial swirling jet. The excitation amplitude is increased in five distinct steps at the burner's Helmholtz resonator mode (i.e., 100 Hz). Two flow states are compared, namely, sub-critical and super-critical vortex breakdown (VB) that occur before and after the critical conical sheet breakdown, respectively. The geometric swirl number is varied in the range 2.14-4.03. Under the influence of external pulsing, global response characteristics are studied based on the topological changes observed in time-averaged 2D flow field. These are obtained from high resolution 2D PIV (particle image velocimetry) in the longitudinal-mid plane. PIV results also illustrate the changes in the normalized vortex core coordinates (rvcc/(rvcc)0 Hz, yvcc/(yvcc)0 Hz) of internal recirculation zone (IRZ). A strong forced response is observed at 100 Hz (excitation frequency) in the convectively unstable region which get amplified based on the magnitude of external forcing. The radial extent of this forced response region at a given excitation amplitude is represented by the acoustic response region (b). The topological placement of the responsive convectively unstable region is a function of both the intensity of imparted swirl (characterized by swirl number) and forcing amplitude. It is observed that for sub-critical VB mode, an increase in the excitation amplitude till a critical value shifts the vortex core centre (particularly, the vortex core moves downstream and radially outwards) leading to drastic fanning-out/widening of the IRZ. This is accompanied by ˜30% reduction in the recirculation velocity of the IRZ. It is also observed that b < R (R: radial distance from central axis to outer shear layer-OSL). At super-critical amplitudes, the sub-critical IRZ topology transits back (the vortex core retracts upstream and radially inwards) and finally undergoes a transverse shrinkage ((4vcc)/(rvcc) 0 Hz decreases by ˜20%) when b ≥ R. In contrast, the vortex core of super-critical breakdown mode consistently spreads radially outwards and is displaced further downstream. Finally, the IRZ fans-out at the threshold excitation amplitude. However, the acoustic response region b is still less than R. This is explained based on the characteristic geometric swirl number (SG) of the flow regimes. The super-critical flow mode with higher SG (hence, higher radial pressure drop due to rotational effect which scales as ΔP ˜ ρuθ2 and acts inwards towards the center line) compared to sub-critical state imposes a greater resistance to the radial outward spread of b. As a result, the acoustic energy supplied to the super-critical flow mode increases the degree of acoustic response at the pulsing frequency and energizes its harmonics (evident from power spectra). As a disturbance amplifier, the stronger convective instability mode within the flow structure of super-critical VB causes the topology to widen/fan-out severely at threshold excitation amplitude.

The relationship between sodium intake and some bone minerals and osteoporosis risk assessment instrument in postmenopausal women.

PubMed

Vafa, Mohammadreza; Soltani, Sepideh; Zayeri, Farid; Niroomand, Mahtab; Najarzadeh, Azadeh

2016-01-01

The results of the studies on the effects of sodium on bone metabolism have been inconsistent. There is no definitive answer to the question of whether sodium restriction can be associated with a lower incidence of osteoporosis. What reinforces the necessity of designing this study is the lack of findings with the approach of examining the effects of sodium on bone in our country. This was a cross-sectional study conducted on 185 retired female teachers aged 45 to 70. Sodium intake was evaluated using two methods: A 24-hour recall and a 12-hour urine sample. To assess bone health, ORAI index was calculated for each individual. Urinary calcium, phosphorus, potassium and serum vitamin D and PTH were measured as laboratory variables. To compare the general characteristics of the participants across tertiles of urinary sodium, the analysis of variance (ANOVA) was used for quantitative variables and the Chi-square test for categorical variables. Phosphorous, calcium and potassium urinary excretion rate increased with the increase in urinary sodium (p<0.05). However, the changes in serum vitamin D, and PTH levels across tertiles of urinary sodium were not significant. Changes in urinary sodium levels were not significant (p=0.933) in ORAI groups (sorted by rating). The relationship between urinary calcium and sodium was apparent in low calcium intake (r=0.415, p<0.001), but not in higher calcium intake (r=0.144, p=0.177). Although urinary calcium and potassium increased with the increase in sodium intake, no relationship was found between sodium and ORAI.

Association Between Sugar-Sweetened Beverage Intake and Proxies of Acculturation Among U.S. Hispanic and Non-Hispanic White Adults

PubMed Central

Park, Sohyun; Blanck, Heidi M.; Dooyema, Carrie A.; Ayala, Guadalupe X.

2015-01-01

Purpose This study examined associations between sugar-sweetened beverage (SSB) intake and acculturation among a sample representing civilian noninstitutionalized U.S. adults. Design Quantitative, cross-sectional study. Setting National. Subjects The 2010 National Health Interview Survey data for 17,142 Hispanics and U.S.-born non-Hispanic whites (≥18 years). Measures The outcome variable was daily SSB intake (nondiet soda, fruit drinks, sports drinks, energy drinks, and sweetened coffee/tea drinks). Exposure variables were Hispanic ethnicity and proxies of acculturation (language of interview, birthplace, and years living in the United States). Analysis We used multivariate logistic regression to estimate adjusted odds ratios (ORs) for the exposure variables associated with drinking SSB ≥ 1 time/d after controlling for covariates. Results The adjusted odds of drinking SSB ≥ 1 time/d was significantly higher among Hispanics who completed the interview in Spanish (OR = 1.65) than U.S.-born non-Hispanic whites. Compared with those who lived in the United States for <5 years, the adjusted odds of drinking SSB ≥ 1 time/d was higher among adults who lived in the United States for 5 to <10 years (OR = 2.72), those who lived in the United States for 10 to <15 years (OR = 2.90), and those who lived in the United States for ≥15 years (OR = 2.41). However, birthplace was not associated with daily SSB intake. Conclusion The acculturation process is complex and these findings contribute to identifying important subpopulations that may benefit from targeted intervention to reduce SSB intake. PMID:27404644

Energy intake, growth rate and body composition of young Labrador Retrievers and Miniature Schnauzers fed different dietary levels of vitamin A.

PubMed

Brenten, Thomas; Morris, Penelope J; Salt, Carina; Raila, Jens; Kohn, Barbara; Brunnberg, Leo; Schweigert, Florian J; Zentek, Jürgen

2014-06-28

Research in rodents has shown that dietary vitamin A reduces body fat by enhancing fat mobilisation and energy utilisation; however, their effects in growing dogs remain unclear. In the present study, we evaluated the development of body weight and body composition and compared observed energy intake with predicted energy intake in forty-nine puppies from two breeds (twenty-four Labrador Retriever (LAB) and twenty-five Miniature Schnauzer (MS)). A total of four different diets with increasing vitamin A content between 5·24 and 104·80 μmol retinol (5000-100 000 IU vitamin A)/4184 kJ (1000 kcal) metabolisable energy were fed from the age of 8 weeks up to 52 (MS) and 78 weeks (LAB). The daily energy intake was recorded throughout the experimental period. The body condition score was evaluated weekly using a seven-category system, and food allowances were adjusted to maintain optimal body condition. Body composition was assessed at the age of 26 and 52 weeks for both breeds and at the age of 78 weeks for the LAB breed only using dual-energy X-ray absorptiometry. The growth curves of the dogs followed a breed-specific pattern. However, data on energy intake showed considerable variability between the two breeds as well as when compared with predicted energy intake. In conclusion, the data show that energy intakes of puppies particularly during early growth are highly variable; however, the growth pattern and body composition of the LAB and MS breeds are not affected by the intake of vitamin A at levels up to 104·80 μmol retinol (100 000 IU vitamin A)/4184 kJ (1000 kcal).

Intake of caffeine from all sources and reasons for use by college students.

PubMed

Mahoney, Caroline R; Giles, Grace E; Marriott, Bernadette P; Judelson, Daniel A; Glickman, Ellen L; Geiselman, Paula J; Lieberman, Harris R

2018-04-10

Caffeine intake in a convenience sample of U.S. college students (N = 1248) was surveyed at five geographically-dispersed United States (U.S.) universities. Intake from coffee, tea, soft drinks, energy drinks, gums, and medications was assessed. Associations between caffeine intake and demographic variables including sex, age, race/ethnicity, family income, general health, exercise, weight variables and tobacco use were examined. Reasons for use of caffeine-containing products were assessed. Caffeine, in any form, was consumed by 92% of students in the past year. Mean daily caffeine consumption for all students, including non-consumers, was 159 mg/d with a mean intake of 173 mg/d among caffeine users. Coffee was the main source of caffeine intake in male (120 mg/d) and female (111 mg/d) consumers. Male and female students consumed 53 vs. 30 mg/d of caffeine in energy drinks, respectively, and 28% consumed energy drinks with alcohol on at least one occasion. Students provided multiple reasons for caffeine use including: to feel awake (79%); enjoy the taste (68%); the social aspects of consumption (39%); improve concentration (31%); increase physical energy (27%); improve mood (18%); and alleviate stress (9%). As in the general U.S. population, coffee is the primary source of caffeine intake among the college students surveyed. Energy drinks provide less than half of total daily caffeine intake but more than among the general population. Students, especially women, consume somewhat more caffeine than the general population of individuals aged 19-30 y but less than individuals aged 31-50 y. Published by Elsevier Ltd.

Hospital outpatients are satisfactory for case-control studies on cancer and diet in China: a comparison of population versus hospital controls.

PubMed

Li, Lin; Zhang, Min; Holman, C D'Arcy J

2013-01-01

To investigate the internal validity of a food-frequency questionnaire (FFQ) developed for use in Chinese women and to compare habitual dietary intakes between population and hospital controls measured by the FFQ. A quantitative FFQ and a short food habit questionnaire (SFHQ) were developed and adapted for cancer and nutritional studies. Habitual dietary intakes were assessed in 814 Chinese women aged 18-81 years (407 outpatients and 407 population controls) by face-to-face interview using the FFQ in Shenyang, Northeast China in 2009-2010. The Goldberg formula (ratio of energy intake to basal metabolic rate, EI/BMR) was used to assess the validity of the FFQ. Correlation analyses compared the SFHQ variables with those of the quantitative FFQ. Differences in dietary intakes between hospital and population controls were investigated. Odds ratios (ORs) and 95% confidence intervals (CIs) were obtained using conditional logistic regression analyses. The partial correlation coefficients were moderate to high (0.42 to 0.80; all p<0.05) for preserved food intake, fat consumption and tea drinking variables between the SFHQ and the FFQ. The average EI/BMR was 1.93 with 88.5% of subjects exceeding the Goldberg cut-off value of 1.35. Hospital controls were comparable to population controls in consumption of 17 measured food groups and mean daily intakes of energy and selected nutrients. The FFQ had reasonable validity to measure habitual dietary intakes of Chinese women. Hospital outpatients provide a satisfactory control group for food consumption and intakes of energy and nutrients measured by the FFQ in a Chinese hospital setting.

A numerical study of axisymmetric compressible non-isothermal and reactive swirling flow

NASA Astrophysics Data System (ADS)

Tavernetti, William E.; Hafez, Mohamed M.

2017-09-01

Non-linear dynamical phenomena in combustion processes is an active area of experimental and theoretical research. This is in large part due to increasingly strict environmental pressures to make gas turbine engines and industrial burners more efficient. Using numerical methods, for steady and unsteady confined and unconfined compressible flow, this study examines the modeling influence of compressibility for axisymmetric swirling flow. The compressible reactive Navier-Stokes equations in terms of stream function, vorticity, circulation are used. Results, details of the numerical algorithms, as well as numerical verification techniques and validation with sources from the literature will be presented. Understanding how vortex breakdown phenomena are affected by modeling reactant consumption with compressibility effect is the main goal of this study.

Jovian Antarctica.

NASA Image and Video Library

2017-02-04

Cyclones swirl around the south pole, and white oval storms can be seen near the limb -- the apparent edge of the planet -- in this image of Jupiter's south polar region taken by the JunoCam imager aboard NASA's Juno spacecraft. The image was acquired on February 2, 2017, at 5:52 a.m. PST (8:52 a.m. EST) from an altitude of 47,600 miles (76,600 kilometers) above Jupiter's swirling cloud deck. Prior to the Feb. 2 flyby, the public was invited to vote for their favorite points of interest in the Jovian atmosphere for JunoCam to image. The point of interest captured here was titled "Jovian Antarctica" by a member of the public, in reference to Earth's Antarctica. http://photojournal.jpl.nasa.gov/catalog/PIA21380

Jupiter Pearl and Swirling Cloud Tops

NASA Image and Video Library

2017-01-19

This amateur-processed image was taken on Dec. 11, 2016, at 9:27 a.m. PST (12:27 p.m. EST), as NASA's Juno spacecraft performed its third close flyby of Jupiter. At the time the image was taken, the spacecraft was about 15,200 miles (24,400 kilometers) from the gas giant planet. The citizen scientist (Eric Jorgensen) cropped the JunoCam image and enhanced the color to draw attention to Jupiter's swirling clouds southeast of the "pearl." The "pearl" is one of eight massive rotating storms at 40 degrees south latitude on Jupiter, known colloquially as the "string of pearls." The processing of this image highlights the turbulence of the clouds in the south temperate belt of the planet. http://photojournal.jpl.nasa.gov/catalog/PIA21377

A composition joint PDF method for the modeling of spray flames

NASA Technical Reports Server (NTRS)

Raju, M. S.

1995-01-01

This viewgraph presentation discusses an extension of the probability density function (PDF) method to the modeling of spray flames to evaluate the limitations and capabilities of this method in the modeling of gas-turbine combustor flows. The comparisons show that the general features of the flowfield are correctly predicted by the present solution procedure. The present solution appears to provide a better representation of the temperature field, particularly, in the reverse-velocity zone. The overpredictions in the centerline velocity could be attributed to the following reasons: (1) the use of k-epsilon turbulence model is known to be less precise in highly swirling flows and (2) the swirl number used here is reported to be estimated rather than measured.

Investigation of the Mechanism of Generation of Acoustic Oscillations inside Complicated Curvilinear Channels

NASA Astrophysics Data System (ADS)

Mitrofanova, O. V.; Bayramukov, A. S.; Fedorinov, A. V.

2017-11-01

There are presented some results of computational-theoretical research on identifying thermo-physical features and topology of high-velocity curved and swirl flows, which are occur inside complicated channels of collector systems, active zones and nuclear power installations equipment with pressurized water reactors. Cylindrical curved channels of different configurations and various combinations of bends and cross sectional areas were considered as modeling objects. Results of computational experiments to determine velocity, pressure, vorticity and temperature fields in transverse and longitudinal sections of the pipeline showed that the complicated geometry of the channels can cause to large-scale swirl of flow, cavitation effects and generation acoustic fluctuations with wide spectrum of sound frequencies for the coolant in the dynamic modes.

A comparison between ultraviolet disinfection and copper alginate beads within a vortex bioreactor for the deactivation of bacteria in simulated waste streams with high levels of colour, humic acid and suspended solids.

PubMed

Thomas, Simon F; Rooks, Paul; Rudin, Fabian; Atkinson, Sov; Goddard, Paul; Bransgrove, Rachel M; Mason, Paul T; Allen, Michael J

2014-01-01

We show in this study that the combination of a swirl flow reactor and an antimicrobial agent (in this case copper alginate beads) is a promising technique for the remediation of contaminated water in waste streams recalcitrant to UV-C treatment. This is demonstrated by comparing the viability of both common and UV-C resistant organisms in operating conditions where UV-C proves ineffective - notably high levels of solids and compounds which deflect UV-C. The swirl flow reactor is easy to construct from commonly available plumbing parts and may prove a versatile and powerful tool in waste water treatment in developing countries.

High stability design for new centrifugal compressor

NASA Technical Reports Server (NTRS)

Kanki, H.; Katayama, K.; Morii, S.; Mouri, Y.; Umemura, S.; Ozawa, U.; Oda, T.

1989-01-01

It is essential that high-performance centrifugal compressors be free of subsynchronous vibrations. A new high-performance centrifugal compressor has been developed by applying the latest rotordynamics knowledge and design techniques: (1) To improve the system damping, a specially designed oil film seal was developed. This seal attained a damping ratio three times that of the conventional design. The oil film seal contains a special damper ring in the seal cartridge. (2) To reduce the destabilizing effect of the labyrinth seal, a special swirl canceler (anti-swirl nozzle) was applied to the balance piston seal. (3) To confirm the system damping margin, the dynamic simulation rotor model test and the full load test applied the vibration exciting test in actual load conditions.

Flow visualization of lateral jet injection into swirling crossflow

NASA Technical Reports Server (NTRS)

Ferrell, G. B.; Aoki, K.; Lilley, D. G.

1985-01-01

Flow visualization experiments have been conducted to characterize the time-mean flowfield of a deflected turbulent jet in a confining cylindrical crossflow. Jet-to-crossflow velocity ratios of 2, 4, and 6 were investigated, under crossflow inlet swirler vane angles of 0 (swirler removed), 45 and 70 degrees. Smoke, neutrally-buoyant helium-filled soap bubbles, and multi-spark flow visualization were employed to highlight interesting features of the deflected jet, as well as the trajectory and spread pattern of the jet. Gross flowfield characterization was obtained for a range of lateral jet-to-crossflow velocity ratios and a range of inlet swirl strengths in the main flow. The flow visualization results agree well with the measurements obtained elsewhere with the six-orientation single hot-wire method.

Manipulation of the swirling flow instability in hydraulic turbine diffuser by different methods of water injection

NASA Astrophysics Data System (ADS)

Rudolf, Pavel; Litera, Jiří; Alejandro Ibarra Bolanos, Germán; Štefan, David

2018-06-01

Vortex rope, which induces substantial pressure pulsations, arises in the draft tube (diffuser) of Francis turbine for off-design operating conditions. Present paper focuses on mitigation of those pulsations using active water jet injection control. Several modifications of the original Susan-Resiga's idea were proposed. All modifications are driven by manipulation of the shear layer region, which is believed to play important role in swirling flow instability. While some of the methods provide results close to the original one, none of them works in such a wide range. Series of numerical experiments support the idea that the necessary condition for vortex rope pulsation mitigation is increasing the fluid momentum along the draft tube axis.

Patterns in food intake correlate with body mass index.

PubMed

Periwal, Vipul; Chow, Carson C

2006-11-01

Quantifying eating behavior may give clues to both the physiological and behavioral mechanisms behind weight regulation. We analyzed year-long dietary records of 29 stable-weight subjects. The records showed wide daily variations of food intake. We computed the temporal autocorrelation and skewness of food intake mass, energy, carbohydrate, fat, and protein. We also computed the cross-correlation coefficient between intake mass and intake energy. The mass of the food intake exhibited long-term trends that were positively skewed, with wide variability among individuals. The average duration of the trends (P = 0.003) and the skewness (P = 0.006) of the food intake mass were significantly correlated with mean body mass index (BMI). We also found that the lower the correlation coefficient between the energy content and the mass of food intake, the higher the BMI. Our results imply that humans in neutral energy balance eating ad libitum exhibit a long-term positive bias in the food intake that operates partially through the mass of food eaten to defend against eating too little more vigorously than eating too much.

Development of a Laboratory Test for Multiport Injector Deposits: Approaches 1 and 2.

DTIC Science & Technology

1987-09-01

developed approximately 20 years ago by the U. S. Army at Southwest Research Institute (SwRI) for screening fuels with a tendency to form intake valve de ...the left in Figure 2 was developed specifically to evaluate the fuel- de - positing tendencies in both cold carburetor throat and hot intake valve areas...Carburetor Throttle U-,Removable Plate and Throat Deposit Sleeve De pos iti n Ass emb ly Variable Poerta Intake Valve Depositing Assembl> 1,� V. -A.C

Inverse Association between Fruit and Vegetable Intake and BMI even after Controlling for Demographic, Socioeconomic and Lifestyle Factors

PubMed Central

Heo, Moonseong; Kim, Ryung S.; Wylie-Rosett, Judith; Allison, David B.; Heymsfield, Steve B.; Faith, Myles S.

2011-01-01

Objective To estimate fruit and vegetable (FV) intake levels of US adult population and evaluate the association between FV intake and BMI status after controlling for confounding demographic, socioeconomic and lifestyle factors. We also sought to identify moderating factors. Methods We used 2007 Behavior Risk Factors Surveillance System (N > 400,000) data. FV intake was dichotomized as ≥5 servings (FV5+) versus <5 servings/day. BMI status was categorized as normal, overweight, and obese. Identification of moderators was performed by testing interactions between BMI status and other variables using bivariate analyses followed by multiple logistic regression analysis incorporating complex survey sampling design features. Results Only 24.6% of US adults consumed ≥5 servings per day and less than 4% consumed 9 or more servings. Overweight (% FV5+ = 23.9%) and obese (21.9%) groups consumed significantly less FV than the normal-weight (27.4%) group (p < 0.0001). This inverse association remained significant even after controlling for potential confounding factors. Multivariate analysis identified five significant moderators (p < 0.0001) after controlling for all evaluated variables: race, sex, smoking status, health coverage, and physical activity. Notably, physically inactive obese males tended to consume the least FV (% FV5+ = 14.7%). Conclusion Current US population FV intake level is below recommended levels. The inverse association between FV intake and obesity was significant and was moderated by demographic, socioeconomic status, and lifestyle factors. These factors should be considered when developing policies and interventions to increase FV intake. PMID:22248995

How is food insecurity associated with dietary behaviors? An analysis with low income, ethnically diverse participants in a nutrition intervention study

PubMed Central

Mello, Jennifer A.; Gans, Kim M.; Risica, Patricia M.; Kirtania, Usree; Strolla, Leslie O.; Fournier, Leanne

2010-01-01

Food insecurity has been associated with a lower nutrient intake as well as a lower intake of fruits and vegetables. However, little is known about the association of food insecurity and dietary behaviors, including food choices and preparation methods. This study examines the relationship between food insecurity and dietary behaviors of low income adults (N = 1874, 55% Hispanic) who completed the baseline telephone survey for a nutrition education study. From April 2003 to August 2004, data were collected on demographics and food security status and validated dietary measures: fruit and vegetable screener and Food Habits Questionnaire (FHQ) were used to assess fat-related behaviors (food choices or preparation methods that lead to an increase or decrease in fat intake). Chi square tests were conducted to compare each demographic variable by food security status. Univariate linear regression models examined dietary variables by food security status in univariate models initially, then in multivariable models adjusting for demographics. Half of participants reported food insecurity. FHQ scores were significantly greater in the food insecure group, reflecting a higher fat intake (P<0.05). Fruit (with juice) intake was significantly greater in the food insecure participants reflecting increased juice intake (P<0.05). Food insecure individuals reported a higher juice intake and a lower frequency of fat-lowering behaviors. Future interventions with food insecure individuals should include nutrition education as well as efforts to increase access and availability to healthier foods. Further qualitative and quantitative research is needed on the relationship between diet and food insecurity. PMID:21111099

Patterns of Weight Control Behavior among 15 year old Girls

PubMed Central

Balantekin, Katherine N.; Birch, Leann L.; Savage, Jennifer S.

2015-01-01

Objective The objectives were to identify and predict patterns of weight control behavior in 15 year old (yo) girls and to examine weight control group differences in energy intake. Method Subjects included 166 girls assessed every 2 years (ys) from age 5 to 15. Latent class analysis was used to identify patterns of weight control behaviors. Antecedent variables (e.g. inhibitory control at 7ys), and concurrent variables (e.g. BMI and dietary intake at 15ys) were included as predictors. Assessments were a combination of survey, interview, and laboratory measures. Results LCA identified four classes of weight control behaviors, Non-dieters (26%), and three dieting groups: Lifestyle (16%), Dieters (43%), and Extreme Dieters (17%). Levels of restraint, weight concerns, and dieting frequency increased across groups, from Non-dieters to Extreme Dieters. BMI at 5ys and inhibitory control at 7ys predicted weight control group at 15ys; e.g. with every one-point decrease in inhibitory control, girls were twice as likely to be Extreme Dieters than Non-dieters. Girls in the Extreme Dieters group were mostly classified as under-reporters, and had the lowest self-reported intake, but ate significantly more in the laboratory. Discussion Among 15yo girls, “dieting” includes a range of both healthy and unhealthy behaviors. Risk factors for membership in a weight control groups are present as early as 5ys. Patterns of intake in the laboratory support the view that lower reported energy intake by Extreme Dieters is likely due under-reporting as an intent to decrease intake, not actual decreased intake. PMID:26284953

Behavioral Self-Regulation and Weight-Related Behaviors in Inner-City Adolescents: A Model of Direct and Indirect Effects

PubMed Central

Isasi, Carmen R.; Wills, Thomas A.

2012-01-01

Background This study examined the association of two distinct self-regulation constructs, effortful control and dysregulation, with weight-related behaviors in adolescents and tested whether these effects were mediated by self-efficacy variables. Methods A school-based survey was conducted with 1771 adolescents from 11 public schools in the Bronx, New York. Self-regulation was assessed by multiple indicators and defined as two latent constructs. Dependent variables included fruit/vegetable intake, intake of snack/junk food, frequency of physical activity, and time spent in sedentary behaviors. Structural equation modeling examined the relation of effortful control and dysregulation to lifestyle behaviors, with self-efficacy variables as possible mediators. Results Study results showed that effortful control had a positive indirect effect on fruit and vegetable intake, mediated by self-efficacy, as well as a direct effect. Effortful control also had a positive indirect effect on physical activity, mediated by self-efficacy. Dysregulation had direct effects on intake of junk food/snacks and time spent in sedentary behaviors. Conclusions These findings indicate that self-regulation characteristics are related to diet and physical activity and that some of these effects are mediated by self-efficacy. Different effects were noted for the two domains of self-regulation. Prevention researchers should consider including self-regulation processes in programs to improve health behaviors in adolescents. PMID:23243551

Too little sleep and an unhealthy diet could increase the risk of sustaining a new injury in adolescent elite athletes.

PubMed

von Rosen, P; Frohm, A; Kottorp, A; Fridén, C; Heijne, A

2017-11-01

Little is known about health variables and if these variables could increase the risk of injuries among adolescent elite athletes. The primary aim was to present overall data on self-perceived stress, nutrition intake, self-esteem, and sleep, as well as gender and age differences, on two occasions among adolescent elite athletes. A secondary aim was to study these health variables as potential risk factors on injury incidence. A questionnaire was e-mailed to 340 adolescent elite athletes on two occasions during a single school year: autumn semester and spring semester. The results show that during autumn semester, the recommended intake of fruits, vegetables, and fish was not met for 20%, 39%, and 43% of the adolescent elite athletes, respectively. The recommended amount of sleep during weekdays was not obtained by 19%. Multiple logistic regression showed that athletes sleeping more than 8 h of sleep during weekdays reduced the odds of injury with 61% (OR, 0.39; 95% CI, 0.16-0.99) and athletes reaching the recommended nutrition intake reduced the odds with 64% (OR, 0.36; 95% CI, 0.14-0.91). Our findings suggest that nutrition intake and sleep volume are of importance in understanding injury incidence. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Variability of nutrients intake, lipid profile and cardiovascular mortality among geographical areas in Spain: The DRECE study.

PubMed

Gómez de la Cámara, Agustín; De Andrés Esteban, Eva; Urrútia Cuchí, Gerard; Calderón Sandubete, Enrique; Rubio Herrera, Miguel Ángel; Menéndez Orenga, Miguel; Lora Pablos, David

2017-11-07

It has often been suggested that cardiovascular mortality and their geographical heterogeneity are associated with nutrients intake patterns and also lipid profile. The large Spanish study Dieta y Riesgo de Enfermedades Cardiovasculares en España (DRECE) investigated this theory from 1991 to 2010. Out of the 4,783 Spanish individuals making up the DRECE cohort, 220 subjects (148 men and 72 women) died (4.62%) during the course of the study. The mean age of patients who died from cardiovascular causes (32 in all) was 61.08 years 95% CI (57.47-64.69) and 70.91% of them were males. The consumption of nutrients and the lipid profile by geographical area, studied by geospatial models, showed that the east and southern area of the country had the highest fat intake coupled to a high rate of unhealthy lipid profile. It was concluded that the spatial geographical analysis showed a relationship between high fat intake, unhealthy lipid profile and cardiovascular mortality in the different geographical areas, with a high variability within the country.

Quantification of total and hexavalent chromium in lager beers: variability between styles and estimation of daily intake of chromium from beer.

PubMed

Vieira, Elsa; Soares, M Elisa; Kozior, Marta; Krejpcio, Zbigniew; Ferreira, Isabel M P L V O; Bastos, M Lourdes

2014-09-17

A survey of the presence of total and hexavalent chromium in lager beers was conducted to understand the variability between different styles of lager beer packaged in glass or cans and to estimate daily intake of total Cr and hexavalent chromium from beer. Graphite-furnace atomic absorption spectroscopy using validated methodologies was applied. Selective extraction of hexavalent chromium was performed using a Chromabond NH2/500 mg column and elution with nitric acid. The detection limits were 0.26 and 0.68 μg L(-1) for total Cr and Cr(VI), respectively. The mean content of total Cr ranged between 1.13 μg L(-1) in canned pale lager and 4.32 μg L(-1) in low-alcohol beers, whereas the mean content of Cr(VI) was <2.51 μg L(-1). Considering an intake of 500 mL of beer, beer consumption can contribute approximately 2.28-8.64 and 1.6-6.17% of the recommended daily intake of chromium for women and men, respectively.

Genetic variability in residual feed intake in rainbow trout clones and testing of indirect selection criteria (Open Access publication).

PubMed

Grima, Laure; Quillet, Edwige; Boujard, Thierry; Robert-Granié, Christèle; Chatain, Béatrice; Mambrini, Muriel

2008-01-01

Little is known about the genetic basis of residual feed intake (RFI) variation in fish, since this trait is highly sensitive to environmental influences, and feed intake of individuals is difficult to measure accurately. The purpose of this work was (i) to assess the genetic variability of RFI estimated by an X-ray technique and (ii) to develop predictive criteria for RFI. Two predictive criteria were tested: loss of body weight during feed deprivation and compensatory growth during re-feeding. Ten heterozygous rainbow trout clones were used. Individual intake and body weight were measured three times at three week intervals. Then, individual body weight was recorded after two cycles of a three-week feed deprivation followed by a three-week re-feeding. The ratio of the genetic variance to the phenotypic variance was found high to moderate for growth, feed intake, and RFI (VG/VP = 0.63+/-0.11, 0.29 +/-0.11, 0.29 +/-0.09, respectively). The index that integrates performances achieved during deprivation and re-feeding periods explained 59% of RFI variations. These results provide a basis for further studies on the origin of RFI differences and show that indirect criteria are good candidates for future selective breeding programs.

Protein Intake and Growth in Preterm Infants

PubMed Central

Tonkin, Emma L.; Collins, Carmel T.

2014-01-01

Objective. This review aimed to investigate the relationship between varying levels of enteral protein intake and growth in preterm infants, regardless of feeding method. Data Sources. Electronic databases were searched for relevant studies, as were review articles, reference lists, and text books. Study Selection. Trials were included if they were randomized or quasirandomized, participants were <37 weeks gestation at birth, and protein intakes were intentionally or statistically different between study groups. Trials reporting weight, length, and head circumference gains in infants fed formula, human milk, or fortified human milk were included. Data Extraction. Studies were categorized by feeding-type and relevant data were extracted into summary tables by one reviewer and cross-checked by a second. Data Synthesis. A meta-analysis could not be conducted due to extensive variability among studies; thus, results were synthesized graphically and narratively. Twenty-four trials met the inclusion criteria and were included in a narrative synthesis and 19 in a graphical synthesis of study results. Conclusions. There was extensive variability in study design, participant characteristics, and study quality. Nonetheless, results are fairly consistent that higher protein intake results in increased growth with graphical representation indicating a potentially linear relationship. Additionally, intakes as high as 4.5 g/kg/day were shown to be safe in infants weighing >1000 g. PMID:27335914

Association between intake of dairy products and short-term memory with and without adjustment for genetic and family environmental factors: A twin study.

PubMed

Ogata, Soshiro; Tanaka, Haruka; Omura, Kayoko; Honda, Chika; Hayakawa, Kazuo

2016-04-01

Previous studies have indicated associations between intake of dairy products and better cognitive function and reduced risk of dementia. However, these studies did not adjust for genetic and family environmental factors that may influence food intake, cognitive function, and metabolism of dairy product nutrients. In the present study, we investigated the association between intake of dairy products and short-term memory with and without adjustment for almost all genetic and family environmental factors using a genetically informative sample of twin pairs. A cross-sectional study was conducted among twin pairs aged between 20 and 74. Short-term memory was assessed as primary outcome variable, intake of dairy products was analyzed as the predictive variable, and sex, age, education level, marital status, current smoking status, body mass index, dietary alcohol intake, and medical history of hypertension or diabetes were included as possible covariates. Generalized estimating equations (GEE) were performed by treating twins as individuals and regression analyses were used to identify within-pair differences of a twin pair to adjust for genetic and family environmental factors. Data are reported as standardized coefficients and 95% confidence intervals (CI). Analyses were performed on data from 78 men and 278 women. Among men, high intake of dairy products was significantly associated with better short-term memory after adjustment for the possible covariates (standardized coefficients = 0.22; 95% CI, 0.06-0.38) and almost all genetic and family environmental factors (standardized coefficients = 0.38; 95% CI, 0.07-0.69). Among women, no significant associations were found between intake of dairy products and short-term memory. Subsequent sensitivity analyses were adjusted for small samples and showed similar results. Intake of dairy product may prevent cognitive declines regardless of genetic and family environmental factors in men. Copyright © 2015 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

The effect of social desirability trait on self-reported dietary measures among multi-ethnic female health center employees.

PubMed

Hébert, J R; Peterson, K E; Hurley, T G; Stoddard, A M; Cohen, N; Field, A E; Sorensen, G

2001-08-01

To evaluate the effect of social desirability trait, the tendency to respond in a manner consistent with societal expectations, on self-reported fruit, vegetable, and macronutrient intake. A 61-item food frequency questionnaire (FFQ), 7-item fruit and vegetable screener, and a single question on combined fruit and vegetable intake were completed by 132 female employees at five health centers in eastern Massachusetts. Intake of fruit and vegetables derived from all three methods and macronutrients from the FFQ were fit as dependent variables in multiple linear regression models (overall and by race/ethnicity and education); independent variables included 3-day mean intakes derived from 24-hour recalls (24HR) and score on the 33-point Marlowe-Crowne Social Desirability scale (the regression coefficient for which reflects its effect on estimates of dietary intake based on the comparison method relative to 24HR). Results are based on the 93 women with complete data and FFQ-derived caloric intake between 450 and 4500 kcal/day. In women with college education, FFQ-derived estimates of total caloric were associated with under-reporting by social desirability trait (e.g., the regression coefficient for total caloric intake was -23.6 kcal/day/point in that group versus 36.1 kcal/day/point in women with education less than college) (difference = 59.7 kcal/day/point, 95% confidence interval (CI) = 13.2, 106.2). Except for the single question on which women with college education tended to under-report (difference =.103 servings/day/point, 95% CI = 0.003, 0.203), there was no association of social desirability trait with self-reported fruit and vegetable intake. The effect of social desirability trait on FFQ reports of macronutrient intake appeared to differ by education, but not by ethnicity or race. The results of this study may have important implications for epidemiologic studies of diet and health in women.

What are the factors that influence the attainment of satisfactory energy intake in pediatric intensive care unit patients receiving enteral or parenteral nutrition?

PubMed

de Menezes, Fernanda Souza; Leite, Heitor Pons; Nogueira, Paulo Cesar Koch

2013-01-01

Children admitted to the intensive care unit (ICU) are at risk of inadequate energy intake. Although studies have identified factors contributing to an inadequate energy supply in critically ill children, they did not take into consideration the length of time during which patients received their estimated energy requirements after having achieved a satisfactory energy intake. This study aimed to identify factors associated with the non-attainment of estimated energy requirements and consider the time this energy intake is maintained. This was a prospective study involving 207 children hospitalized in the ICU who were receiving enteral and/or parenteral nutrition. The outcome variable studied was whether 90% of the estimated basal metabolic rate was maintained for at least half of the ICU stay (satisfactory energy intake). The exposure variables for outcome were gender, age, diagnosis, use of vasopressors, malnutrition, route of nutritional support, and Pediatric Index of Mortality and Pediatric Logistic Organ Dysfunction scores. Satisfactory energy intake was attained by 20.8% of the patients, within a mean time of 5.07 ± 2.48 d. In a multivariable analysis, a diagnosis of heart disease (odds ratio 3.62, 95% confidence interval 1.03-12.68, P = 0.045) increased the risk of insufficient energy intake, whereas malnutrition (odds ratio 0.43, 95% confidence interval 0.20-0.92, P = 0.030) and the use of parenteral nutrition (odds ratio 0.34, 95% confidence interval 0.15-0.77, P = 0.001) were protective factors against this outcome. A satisfactory energy intake was reached by a small proportion of patients during their ICU stay. Heart disease was an independent risk factor for the non-attainment of satisfactory energy intake, whereas malnutrition and the use of parenteral nutrition were protective factors against this outcome. Copyright © 2013 Elsevier Inc. All rights reserved.

Factors associated with low water intake among US high school students - National Youth Physical Activity and Nutrition Study, 2010.

PubMed

Park, Sohyun; Blanck, Heidi M; Sherry, Bettylou; Brener, Nancy; O'Toole, Terrence

2012-09-01

Drinking plain water instead of sugar-sweetened beverages is one approach for reducing energy intake. Only a few studies have examined characteristics associated with plain water intake among US youth. The purpose of our cross-sectional study was to examine associations of demographic characteristics, weight status, dietary habits, and other behavior-related factors with plain water intake among a nationally representative sample of US high school students. The 2010 National Youth Physical Activity and Nutrition Study data for 11,049 students in grades 9 through 12 were used. Multivariable logistic regression analysis was used to calculate adjusted odds ratios (ORs) and 95% CIs for variables associated with low water intake (<3 times/day). Nationwide, 54% of high school students reported drinking water <3 times/day. Variables significantly associated with a greater odds for low water intake were age ≤15 years (OR 1.1), consuming <2 glasses/day of milk (OR 1.5), nondiet soda ≥1 time/day (OR 1.6), other sugar-sweetened beverages ≥1 time/day (OR 1.4), fruits and 100% fruit juice <2 times/day (OR 1.7), vegetables <3 times/day (OR 2.3), eating at fast-food restaurants 1 to 2 days/week and ≥3 days/week (OR 1.3 and OR 1.4, respectively), and being physically active ≥60 minutes/day on <5 days/week (OR 1.6). Being obese was significantly associated with reduced odds for low water intake (OR 0.7). The findings of these significant associations of low water intake with poor diet quality, frequent fast-food restaurant use, and physical inactivity may be used to tailor intervention efforts to increase plain water intake as a substitute for sugar-sweetened beverages and to promote healthy lifestyles. Published by Elsevier Inc.

Predictors of milk consumption in a population of 17- to 35-year-old military personnel.

PubMed

Klesges, R C; Harmon-Clayton, K; Ward, K D; Kaufman, E M; Haddock, C K; Talcott, G W; Lando, H A

1999-07-01

The purpose of this investigation was to survey an entire population of Air Force recruits (N = 32,144) regarding milk consumption and demographic and health-related factors that may predict milk consumption. All subjects were required to fill out a 53-item health survey at the start of basic military training. All recruits who entered the US Air Force from August 1995 to August 1996 participated in this study (N = 32,144). Potential correlates of milk intake were analyzed using Spearman rank order correlations and multiple linear regression. Variables were removed if they did not make a meaningful contribution to variance in milk intake. Because of skewed distributions, several variables were dichotomized (e.g., age: 17 to 24 vs 25 to 35 years). In terms of milk consumption, 51.7% of the respondents reported intake of fewer than 1 serving per day; only 17.9% reported intake of 3 servings or more per day. Milk intake was positively associated with body weight and fruit/vegetable intake and negatively associated with age, education level, reported milk-related gastric distress, physical activity level, dieting frequency, and concern about weight. Gender (women reported lower intake) and ethnicity (minorities reported lower intake) were independently related to milk consumption. Of all respondents, 16.1% reported themselves to have milk-related gastric distress, but rates varied depending on age, gender, and ethnicity (ranging from 10.2% for younger non-Hispanic white men to 60.4% for older Asian men). Despite the efforts of large, costly campaigns designed to increase milk consumption, self-reported milk consumption in young adults is extremely low. Given the importance of dairy products as a major source of calcium in the American diet, dietetics practitioners should assess milk consumption among young adults to ensure sufficient calcium intake to maximize peak bone mass in this group.

Pretreatment attrition from couple therapy for male drug abusers.

PubMed

Kelly, Shalonda; Epstein, Elizabeth E; McCrady, Barbara S

2004-01-01

This study tracked pretreatment attrition of 120 callers, 84 of whom were potentially eligible for outpatient couple treatment for male drug abuse. Demographic, significant other, substance use, and access related variables were examined as predictors of intake and treatment entry. Results were similar to other findings regarding variables associated with initiation of individual substance use treatment, and 29% of eligible callers entered treatment. Men whose partners did not use substances or who used in moderation were more likely to attend the intake session, and couples who received referrals were more likely to enter treatment than those who responded to a newspaper advertisement.

Health Effects of Low-Carbohydrate Diets: Where Should New Research Go?

PubMed Central

Wylie-Rosett, Judith; Aebersold, Karin; Conlon, Beth; Isasi, Carmen R.; Ostrovsky, Natania W.

2013-01-01

There has been considerable debate about the metabolic effects of restricting carbohydrate intake in weight and diabetes management. However, the American Diabetes Association has noted that weight and metabolic improvements can be achieved with low carbohydrate, low fat (implicitly higher carbohydrate), or a Mediterranean style diet (usually an intermediate level of carbohydrate). Our paper addresses variability in the definition for low or restricted carbohydrate, the effects of carbohydrate restriction on diabetes-related health outcomes, strategies for restricting carbohydrate intake, and potential genetic variability in response to dietary carbohydrate restriction. Issues for future research are also addressed. PMID:23266565

Midlife women, bone health, vegetables, herbs and fruit study. The Scarborough Fair study protocol.

PubMed

Gunn, Caroline A; Weber, Janet L; Kruger, Marlena C

2013-01-10

Bone loss is accelerated in middle aged women but increased fruit/vegetable intake positively affects bone health by provision of micronutrients essential for bone formation, buffer precursors which reduce acid load and phytochemicals affecting inflammation and oxidative stress. Animal studies demonstrated bone resorption inhibiting properties of specific vegetables, fruit and herbs a decade ago. To increase fruit/vegetable intake in post menopausal women to 9 servings/day using a food specific approach to significantly reduce dietary acid load and include specific vegetables, fruit and herbs with bone resorbing inhibiting properties to assess effect on bone turnover, metabolic and inflammatory markers. The Scarborough Fair Study is a randomised active comparator controlled multi centre trial. It aimed to increase fruit and vegetable intake in 100 post menopausal women from ≤ 5 servings/day to ≥ 9 servings/day for 3 months. The women in the dietary intervention were randomly assigned to one of the two arms of the study. Both groups consumed ≥ 9 servings/day of fruit/vegetables and selected herbs but the diet of each group emphasised different fruit/vegetables/herbs with one group (B) selecting from a range of vegetables, fruit and culinary herbs with bone resorbing inhibiting properties. 50 women formed a negative control group (Group C usual diet). Primary outcome variables were plasma bone markers assessed at baseline, 6 weeks and 12 weeks. Secondary outcome variables were plasma inflammation and metabolic markers and urinary electrolytes (calcium, magnesium, potassium and sodium) assessed at baseline and 12 weeks. Dietary intake and urine pH change also were outcome variables. The dietary change was calculated with 3 day diet diaries and a 24 hour recall. Intervention participants kept a twice weekly record of fruit, vegetable and herb intake and urine pH. This study will provide information on midlife women's bone health and how a dietary intervention increasing fruit and vegetable/herb intake affects bone, inflammatory and metabolic markers and urinary electrolyte excretion. It assesses changes in nutrient intake, estimated dietary acid load and sodium: potassium ratios. The study also explores whether specific fruit/vegetables and herbs with bone resorbing properties has an effect on bone markers. ACTRN 12611000763943.

Impact of singlehood during pregnancy on dietary intake and birth outcomes- a study in the Norwegian Mother and Child Cohort Study.

PubMed

Farbu, Jorunn; Haugen, Margaretha; Meltzer, Helle Margrete; Brantsæter, Anne Lise

2014-12-05

Little attention has been given to the impact of singlehood during pregnancy. The aim of this study was to examine the impact of marital status on diet during pregnancy and pregnancy outcome. The study population comprised 62,773 women participating in the Norwegian Mother and Child Cohort Study. Marital status was categorised into singles living alone, singles living with parents and married/cohabiting (reference group). Participants answered a general health questionnaire in gestational week 15-17 and a food frequency questionnaire in gestational week 22. We used nonparametric tests to compare dietary intakes by marital status, and multiple logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for infants being small for gestational age (SGA), large for gestational age (LGA), and preterm delivery (defined as delivery before gestational week 37). Single women living with parents had lower intakes of fruits and vegetables, higher intake of total energy, higher proportion of energy from added sugar, and lower intake of fibre than the reference group. Singles living alone also had a higher intake of added sugar. In both of the single groups, daily smoking was more prevalent than in women living with a partner. In analyses adjusted for maternal age, pre-pregnancy BMI, energy intake, energy contributed by protein, education, income, parity and nausea, single women living alone had increased risk of SGA with OR = 1.27 (95% CI: 1.05, 1.55). When smoking was included among the confounding variables, the association was no longer significant. Likewise, singles living alone had increased risk of preterm delivery, with OR = 1.32 (95% CI: 1.01, 1.72) in a partly adjusted model, but the association did not remain significant in a model fully adjusted for confounding variables. Single mothers had lower dietary quality and included more smokers than women who lived with a partner. Single mothers living alone had higher prevalence of SGA and preterm delivery, but the associations with adverse pregnancy outcomes were confounded by other variables. This study shows that single mothers should be given special attention during antenatal care and counselling.

Exposure to polycyclic aromatic hydrocarbons, arsenic and environmental tobacco smoke, nutrient intake, and oxidative stress in Japanese preschool children.

PubMed

Mori, Takuya; Yoshinaga, Jun; Suzuki, Kei; Mizoi, Miho; Adachi, Shu-Ichi; Tao, Hiroaki; Nakazato, Tetsuya; Li, Yun-Shan; Kawai, Kazuaki; Kasai, Hiroshi

2011-07-01

The association between oxidative stress and exposure to environmental chemicals was assessed in a group of Japanese preschool children. The concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), 1-hydroxypyrene (1-OHP), inorganic arsenic (iAs) and monomethylarsonic acid (MMA), and cotinine in spot urine samples, collected from 134 children (3-6 yrs) from a kindergarten in Kanagawa, Japan, were measured as biomarkers of oxidative stress or exposure to environmental chemicals. For 76 subjects of the 134, intakes of anti-oxidant nutrients (vitamins A, C, and E, manganese, copper, zinc and selenium (Se)) were estimated from a food consumption survey carried out 2-4 weeks after urine sampling and by urine analysis (Se). The median (min-max) creatinine-corrected concentrations of urinary biomarkers were 4.45 (1.98-12.3), 0.127 (0.04-2.41), 4.78 (1.18-12.7), and 0.62 (<0.6-19.0) μg/g cre for 8-OHdG, 1-OHP, iAs+MMA, and cotinine, respectively. Multiple regression analysis was carried out using 8-OHdG concentration as a dependent variable and urinary biomarkers of exposure and Se intake, intakes of vitamins and biological attributes of the subjects as independent variables. To explain 8-OHdG concentrations, intake of vitamin A and age were significant variables with negative coefficients, while 1-OHP concentration had a positive coefficient. These results indicated that oxidative stress of children is affected by chemical exposure at environmental levels, by nutrient intake and by physiological factors in a complex manner. On the other hand, unstable statistical results due to sub-grouping of subject, based on the availability of food consumption data, were found: the present results should further be validated by future studies with suitable research design. Copyright © 2011 Elsevier B.V. All rights reserved.

Diary Data Subjected to Cluster Analysis of Intake/Output/Void Habits with Resulting Clusters Compared by Continence Status, Age, Race

PubMed Central

Miller, Janis M; Guo, Ying; Rodseth, Sarah Becker

2011-01-01

Background Data that incorporate the full complexity of healthy beverage intake and voiding frequency do not exist; therefore, clinicians reviewing bladder habits or voiding diaries for continence care must rely on expert opinion recommendations. Objective To use data-driven cluster analyses to reduce complex voiding diary variables into discrete patterns or data cluster profiles, descriptively name the clusters, and perform validity testing. Method Participants were 352 community women who filled out a 3-day voiding diary. Six variables (void frequency during daytime hours, void frequency during nighttime hours, modal output, total output, total intake, and body mass index) were entered into cluster analyses. The clusters were analyzed for differences by continence status, age, race (Black women, n = 196 White women, n = 156), and for those who were incontinent, by leakage episode severity. Results Three clusters emerged, labeled descriptively as Conventional, Benchmark, and Superplus. The Conventional cluster (68% of the sample) demonstrated mean daily intake of 45 ±13 ounces; mean daily output of 37 ± 15 ounces, mean daily voids 5 ± 2 times, mean modal daytime output 10±0.5 ounces, and mean nighttime voids 1±1 times. The Superplus cluster (7% of the sample) showed double or triple these values across the 5 variables, and the Benchmark cluster (25%) showed values consistent with current popular recommendations on intake and output (e.g., meeting or exceeding the 8 × 8 fluid intake rule of thumb). The clusters differed significantly (p < .05) by age, race, amount of irritating beverages consumed, and incontinence status. Discussion Identification of three discrete clusters provides for a potential parsimonious but data-driven means of classifying individuals for additional epidemiological or clinical study. The clinical utility rests with potential for intervening to move an individual from a high risk to low risk cluster with regards to incontinence. PMID:21317828

The Use and Interpretation of Sodium Concentrations in Casual (Spot) Urine Collections for Population Surveillance and Partitioning of Dietary Iodine Intake Sources

PubMed Central

Conkle, Joel; van der Haar, Frits

2016-01-01

In 2013, the World Health Organization (WHO) called for joint surveillance of population salt and iodine intakes using urinary analysis. 24-h urine collection is considered the gold standard for salt intake assessment, but there is an emerging consensus that casual urine sampling can provide comparable information for population-level surveillance. Our review covers the use of the urinary sodium concentration (UNaC) and the urinary iodine concentration (UIC) from casual urine samples to estimate salt intakes and to partition the sources of iodine intakes. We reviewed literature on 24-h urinary sodium excretion (UNaE) and UNaC and documented the use of UNaC for national salt intake monitoring. We combined information from our review of urinary sodium with evidence on urinary iodine to assess the appropriateness of partitioning methods currently being adapted for cross-sectional survey analyses. At least nine countries are using casual urine collection for surveillance of population salt intakes; all these countries used single samples. Time trend analyses indicate that single UNaC can be used for monitoring changes in mean salt intakes. However; single UNaC suffers the same limitation as single UNaE; i.e., an estimate of the proportion excess salt intake can be biased due to high individual variability. There is evidence, albeit limited, that repeat UNaC sampling has good agreement at the population level with repeat UNaE collections; thus permitting an unbiased estimate of the proportion of excess salt intake. High variability of UIC and UNaC in single urine samples may also bias the estimates of dietary iodine intake sources. Our review concludes that repeated collection, in a sub-sample of individuals, of casual UNaC data would provide an immediate practical approach for routine monitoring of salt intake, because it overcomes the bias in estimates of excess salt intake. Thus we recommend more survey research to expand the evidence-base on predicted-UNaE from repeat casual UNaC sampling. We also conclude that the methodology for partitioning the sources of iodine intake based on the combination of UIC and UNaC measurements in casual urine samples can be improved by repeat collections of casual data; which helps to reduce regression dilution bias. We recommend more survey research to determine the effect of regression dilution bias and circadian rhythms on the partitioning of dietary iodine intake sources. PMID:28025546

Chronic social isolation and chronic variable stress during early development induce later elevated ethanol intake in adult C57BL/6J mice.

PubMed

Lopez, Marcelo F; Doremus-Fitzwater, Tamara L; Becker, Howard C

2011-06-01

Experience with stress situations during early development can have long-lasting effects on stress- and anxiety-related behaviors. Importantly, this can also favor drug self-administration. These studies examined the effects of chronic social isolation and/or variable stress experiences during early development on subsequent voluntary ethanol intake in adult male and female C57BL/6J mice. The experiments were conducted to evaluate the effect of chronic isolation between weaning and adulthood (Experiment 1), chronic isolation during adulthood (Experiment 2), and chronic variable stress (CVS) alone or in combination with chronic social isolation between weaning and adulthood (Experiment 3) on subsequent voluntary ethanol intake. Mice were born in our facility and were separated into two housing conditions: isolate housed (one mouse/cage) or group housed (four mice/cage) according to sex. Separate groups were isolated for 40 days starting either at time of weaning postnatal day 21 (PD 21) (early isolation, Experiments 1 and 3) or at adulthood (PD 60: late isolation, Experiment 2). The effects of housing condition on subsequent ethanol intake were assessed starting at around PD 65 in Experiments 1 and 3 or PD 105 days in Experiment 2. In Experiment 3, starting at PD 32, isolate-housed and group-housed mice were either subjected to CVS or left undisturbed. CVS groups experienced random presentations of mild stressors for 14 days, including exposure to an unfamiliar open field, restraint, physical shaking, and forced swim, among others. All mice were tested for ethanol intake for 14 days using a two-bottle choice (ethanol 15% vol/vol vs. water) for a 2-h limited access procedure. Early social isolation resulted in greater ethanol intake compared with the corresponding group-housed mice (Experiment 1). In contrast, social isolation during adulthood (late isolation) did not increase subsequent ethanol intake compared with the corresponding group-housed mice (Experiment 2). For mice that did not experience CVS, early social isolation resulted in greater ethanol intake compared with group-housed mice (Experiment 3). CVS subsequently resulted in a significant increase in ethanol intake in group-housed mice, but CVS failed to further increase ethanol intake in mice that experienced chronic social isolation early in life (Experiment 3). Overall, female mice consumed more ethanol than males, whether isolated (early or late) or group housed. These results indicate that early but not late social isolation can subsequently influence ethanol consumption in C57BL/6J mice. Thus, the developmental timing of chronic social isolation appears to be an important factor in defining later effects on ethanol self-administration behavior. In addition, experience with CVS early in life results in elevated ethanol intake later in adulthood. Taken together, these results emphasize the important role of early stress experiences that modulate later voluntary ethanol intake during adulthood. Copyright © 2011 Elsevier Inc. All rights reserved.

Numerical simulation of convection and heat transfer in Czochralski crystal growth by multiple-relaxation-time LBM

NASA Astrophysics Data System (ADS)

Liu, Ding; Huang, Weichao; Zhang, Ni

2017-07-01

A two-dimensional axisymmetric swirling model based on the lattice Boltzmann method (LBM) in a pseudo Cartesian coordinate system is posited to simulate Czochralski (Cz) crystal growth in this paper. Specifically, the multiple-relaxation-time LBM (MRT-LBM) combined with the finite difference method (FDM) is used to analyze the melt convection and heat transfer in the process of Cz crystal growth. An incompressible axisymmetric swirling MRT-LB D2Q9 model is applied to solve for the axial and radial velocities by inserting thermal buoyancy and rotational inertial force into the two-dimensional lattice Boltzmann equation. In addition, the melt temperature and the azimuthal velocity are solved by MRT-LB D2Q5 models, and the crystal temperature is solved by FDM. The comparison results of stream functions values of different methods demonstrate that our hybrid model can be used to simulate the fluid-thermal coupling in the axisymmetric swirling model correctly and effectively. Furthermore, numerical simulations of melt convection and heat transfer are conducted under the conditions of high Grashof (Gr) numbers, within the range of 105 ˜ 107, and different high Reynolds (Re) numbers. The experimental results show our hybrid model can obtain the exact solution of complex crystal-growth models and analyze the fluid-thermal coupling effectively under the combined action of natural convection and forced convection.

Use of canonical variate analysis biplot in examination of choline content data of some foods.

PubMed

Alkan, Baris; Atakan, Cemal

2011-03-01

Adequate intake (AI) of choline as part of the daily diet can help prevent major diseases. Low choline intake is a major risk factor for liver and several neurological disorders. Extreme choline consumption may cause diseases such as hypotension, sweating, diarrhea, and fishy body odor. The AI of choline is 425 mg/day for adult women; higher for pregnant and lactating women. The AI for adult men is 550 mg/day. The total choline content of foods is calculated as the sum of free choline, glycerophosphocholine, phosphocholine, phosphatidylcholine and sphingomyelin. These are called the choline variables. Observed values of choline variables may be different in amounts of nutrients. So different food groups in terms of choline variables are useful to compare. The present paper shows the advantages of using canonical variate analysis biplot to optimally separate groups and explore the differentiality of choline variables amounts in foods.

Validation of beverage intake methods vs. hydration biomarkers; a short review.

PubMed

Nissensohn, Mariela; Ruano, Cristina; Serra-Majem, Lluis

2013-11-01

Fluid intake is difficult to monitor. Biomarkers of beverage intake are able to assess dietary intake/hydration status without the bias of self-reported dietary intake errors and also the intra-individual variability. Various markers have been proposed to assess hydration, however, to date; there is a lack of universally accepted biomarker that reflects changes of hydration status in response to changes in beverage intake. We conduct a review to find out the questionnaires of beverage intake available in the scientific literature to assess beverage intake and hydration status and their validation against hydration biomarkers. A scientific literature search was conducted. Only two articles were selected, in which, two different beverage intake questionnaires designed to capture the usual beverage intake were validated against Urine Specific Gravidity biomarker (Usg). Water balance questionnaire (WBQ) reported no correlations in the first study and the Beverage Intake Questionnaire (BEVQ), a quantitative Food frequency questionnaire (FFQ) in the second study, also found a negative correlation. FFQ appears to measure better beverage intake than WBQ when compared with biomarkers. However, the WBQ seems to be a more complete method to evaluate the hydration balance of a given population. Further research is needed to understand the meaning of the different correlations between intake estimates and biomarkers of beverage in distinct population groups and environments. Copyright AULA MEDICA EDICIONES 2013. Published by AULA MEDICA. All rights reserved.

Main Sources, Socio-Demographic and Anthropometric Correlates of Salt Intake in Austria

PubMed Central

Hasenegger, Verena; Rust, Petra; Purtscher, Anna Elisabeth; Erler, Judith; Ekmekcioglu, Cem

2018-01-01

Excessive salt intake is known to increase blood pressure and cardiovascular risk. Nevertheless, salt intake exceeds the recommendations in most countries. To face this problem, it is important to identify high consumers as well as the main contributors of salt intake. Overall, data of 2018 adults between 18 and 64 years were analysed to determine the main sources, socio-demographic and anthropometric correlates of salt intake. Dietary intake was assessed from 24-h-recalls, information on socio-demographic characteristics was obtained using a questionnaire and anthropometric data were measured. Salt intake was significantly higher in males than in females. There was a significant positive association between salt intake and body mass index. No significant differences in salt intake were observed for other variables including affluence, educational level, smoking status and physical activity. The main contributor to salt intake were condiments including table salt (32.6%), followed by cereals and cereal products (27.0%), meat and meat products (16.1%) and dairy products (14.0%). These results highlight that specific population groups need to be targeted by public health initiatives and that a reduction in salt intake can only be achieved in tandem with the food producers by the reduction of salt in processed foods. PMID:29509671

Advanced technology for reducing aircraft engine pollution

NASA Technical Reports Server (NTRS)

Jones, R. E.

1973-01-01

The proposed EPA regulations covering emissions of gas turbine engines will require extensive combustor development. The NASA is working to develop technology to meet these goals through a wide variety of combustor research programs conducted in-house, by contract, and by university grant. In-house efforts using the swirl-can modular combustor have demonstrated sizable reduction in NO emission levels. Testing to reduce idle pollutants has included the modification of duplex fuel nozzles to air-assisted nozzles and an exploration of the potential improvements possible with combustors using fuel staging and variable geometry. The Experimental Clean Combustor Program, a large contracted effort, is devoted to the testing and development of combustor concepts designed to achieve a large reduction in the levels of all emissions. This effort is planned to be conducted in three phases with the final phase to be an engine demonstration of the best reduced emission concepts.

So Many Brands and Varieties to Choose from: Does This Compromise the Control of Food Intake in Humans?

PubMed Central

Hardman, Charlotte A.; Ferriday, Danielle; Kyle, Lesley; Rogers, Peter J.; Brunstrom, Jeffrey M.

2015-01-01

The recent rise in obesity is widely attributed to changes in the dietary environment (e.g., increased availability of energy-dense foods and larger portion sizes). However, a critical feature of our “obesogenic environment” may have been overlooked - the dramatic increase in “dietary variability” (the tendency for specific mass-produced foods to be available in numerous varieties that differ in energy content). In this study we tested the hypothesis that dietary variability compromises the control of food intake in humans. Specifically, we examined the effects of dietary variability in pepperoni pizza on two key outcome variables; i) compensation for calories in pepperoni pizza and ii) expectations about the satiating properties of pepperoni pizza (expected satiation). We reasoned that dietary variability might generate uncertainty about the postingestive effects of a food. An internet-based questionnaire was completed by 199 adults. This revealed substantial variation in exposure to different varieties of pepperoni pizza. In a follow-up study (n= 66; 65% female), high pizza variability was associated with i) poorer compensation for calories in pepperoni pizza and ii) lower expected satiation for pepperoni pizza. Furthermore, the effect of uncertainty on caloric compensation was moderated by individual differences in decision making (loss aversion). For the first time, these findings highlight a process by which dietary variability may compromise food-intake control in humans. This is important because it exposes a new feature of Western diets (processed foods in particular) that might contribute to overeating and obesity. PMID:25923118