Assessment of analytical techniques for predicting solid propellant exhaust plumes and plume impingement environments

NASA Technical Reports Server (NTRS)

Tevepaugh, J. A.; Smith, S. D.; Penny, M. M.

1977-01-01

An analysis of experimental nozzle, exhaust plume, and exhaust plume impingement data is presented. The data were obtained for subscale solid propellant motors with propellant Al loadings of 2, 10 and 15% exhausting to simulated altitudes of 50,000, 100,000 and 112,000 ft. Analytical predictions were made using a fully coupled two-phase method of characteristics numerical solution and a technique for defining thermal and pressure environments experienced by bodies immersed in two-phase exhaust plumes.

Experimental comparative study of doublet and triplet impinging atomization of gelled fuel based on PIV

NASA Astrophysics Data System (ADS)

Yang, Jian-lu; Li, Ning; Weng, Chun-sheng

2016-10-01

Gelled propellant is promising for future aerospace application because of its combination of the advantages of solid propellants and liquid propellants. An effort was made to reveal the atomization properties of gelled fuel by particle image velocimetry (PIV) system. The gelled fuel which was formed by gasoline and Nano-silica was atomized using a like-doublet impingement injector and an axisymmetric like-triplet impingement injector. The orifice diameter and length of the nozzle used in this work were of 0.8mm, 4.8mm, respectively. In the impinging spray process, the impingement angles were set at 90° and 120°, and the injection pressures were of 0.50MPa and 1.00MPa. The distance from the exit of the orifice to the impingement point was fixed at 9.6mm. In this study, high-speed visualization and temporal resolution particle image velocimetry techniques were employed to investigate the impingement atomization characteristics. The experimental investigation demonstrated that a long narrow high speed droplets belt formed around the axis of symmetry in the like-doublet impinging atomization area. However, there was no obvious high-speed belt with impingement angle 2θ = 90° and two high-speed belts appeared with impingement angle 2θ = 120° in the like-doublet impingement spray field. The high droplet velocity zone of the like-doublet impingement atomization symmetrically distributed around the central axis, and that of the like-triplet impingement spray deflected to the left of the central axis - opposite of injector. Although the droplets velocity distribution was asymmetry of like-triplet impingement atomization, the injectors were arranged like axisymmetric conical shape, and the cross section of spray area was similar to a circle rather than a narrow rectangle like the like-doublet impingement atomization.

Collection Efficiency and Ice Accretion Characteristics of Two Full Scale and One 1/4 Scale Business Jet Horizontal Tails

NASA Technical Reports Server (NTRS)

Bidwell, Colin S.; Papadakis, Michael

2005-01-01

Collection efficiency and ice accretion calculations have been made for a series of business jet horizontal tail configurations using a three-dimensional panel code, an adaptive grid code, and the NASA Glenn LEWICE3D grid based ice accretion code. The horizontal tail models included two full scale wing tips and a 25 percent scale model. Flow solutions for the horizontal tails were generated using the PMARC panel code. Grids used in the ice accretion calculations were generated using the adaptive grid code ICEGRID. The LEWICE3D grid based ice accretion program was used to calculate impingement efficiency and ice shapes. Ice shapes typifying rime and mixed icing conditions were generated for a 30 minute hold condition. All calculations were performed on an SGI Octane computer. The results have been compared to experimental flow and impingement data. In general, the calculated flow and collection efficiencies compared well with experiment, and the ice shapes appeared representative of the rime and mixed icing conditions for which they were calculated.

SVDS plume impingement modeling development. Sensitivity analysis supporting level B requirements

NASA Technical Reports Server (NTRS)

Chiu, P. B.; Pearson, D. J.; Muhm, P. M.; Schoonmaker, P. B.; Radar, R. J.

1977-01-01

A series of sensitivity analyses (trade studies) performed to select features and capabilities to be implemented in the plume impingement model is described. Sensitivity analyses were performed in study areas pertaining to geometry, flowfield, impingement, and dynamical effects. Recommendations based on these analyses are summarized.

Subsampling program for the estimation of fish impingement

NASA Astrophysics Data System (ADS)

Beauchamp, John J.; Kumar, K. D.

1984-11-01

Federal regulations require operators of nuclear and coal-fired power-generating stations to estimate the number of fish impinged on intake screens. During winter months, impingement may range into the hundreds of thousands for certain species, making it impossible to count all intake screens completely. We present graphs for determinig the appropriate“optimal” subsample that must be obtained to estimate the total number impinged. Since the number of fish impinged tends to change drastically within a short time period, the subsample size is determined based on the most recent data. This allows for the changing nature of the species-age composition of the impinged fish. These graphs can also be used for subsampling fish catches in an aquatic system when the size of the catch is too large to sample completely.

Numerical study of a confined slot impinging jet with nanofluids

PubMed Central

2011-01-01

Background Heat transfer enhancement technology concerns with the aim of developing more efficient systems to satisfy the increasing demands of many applications in the fields of automotive, aerospace, electronic and process industry. A solution for obtaining efficient cooling systems is represented by the use of confined or unconfined impinging jets. Moreover, the possibility of increasing the thermal performances of the working fluids can be taken into account, and the introduction of nanoparticles in a base fluid can be considered. Results In this article, a numerical investigation on confined impinging slot jet working with a mixture of water and Al2O3 nanoparticles is described. The flow is turbulent and a constant temperature is applied on the impinging. A single-phase model approach has been adopted. Different geometric ratios, particle volume concentrations and Reynolds number have been considered to study the behavior of the system in terms of average and local Nusselt number, convective heat transfer coefficient and required pumping power profiles, temperature fields and stream function contours. Conclusions The dimensionless stream function contours show that the intensity and size of the vortex structures depend on the confining effects, given by H/W ratio, Reynolds number and particle concentrations. Furthermore, for increasing concentrations, nanofluids realize increasing fluid bulk temperature, as a result of the elevated thermal conductivity of mixtures. The local Nusselt number profiles show the highest values at the stagnation point, and the lowest at the end of the heated plate. The average Nusselt number increases for increasing particle concentrations and Reynolds numbers; moreover, the highest values are observed for H/W = 10, and a maximum increase of 18% is detected at a concentration equal to 6%. The required pumping power as well as Reynolds number increases and particle concentrations grow, which is almost 4.8 times greater than the values calculated in the case of base fluid. List of symbols PMID:21711743

Use of microgravity sensors for quantification of space shuttle orbiter vernier reaction control system induced environments

NASA Technical Reports Server (NTRS)

Friend, Robert B.

1998-01-01

In the modeling of spacecraft dynamics it is important to accurately characterize the environment in which the vehicle operates, including the environments induced by the vehicle itself. On the Space Shuttle these induced environmental factors include reaction control system plume. Knowledge of these environments is necessary for performance of control systems and loads analyses, estimation of disturbances due to thruster firings, and accurate state vector propagation. During the STS-71 mission, while the Orbiter was performing attitude control for the mated Orbiter/Mir stack, it was noted that the autopilot was limit cycling at a rate higher than expected from pre-flight simulations. Investigations during the mission resulted in the conjecture that an unmodelled plume impingement force was acting upon the orbiter elevons. The in-flight investigations were not successful in determining the actual magnitude of the impingement, resulting in several sequential post-flight investigations. Efforts performed to better quantify the vernier reaction control system induced plume impingement environment of the Space Shuttle orbiter are described in this paper, and background detailing circumstances which required the more detailed knowledge of the RCS self impingement forces, as well as a description of the resulting investigations and their results is presented. The investigations described in this paper applied microgravity acceleration data from two shuttle borne microgravity experiments, SAMS and OARE, to the solution of this particular problem. This solution, now used by shuttle analysts and mission planners, results in more accurate propellant consumption and attitude limit cycle estimates in preflight analyses, which are critical for pending International Space Station missions.

Development of an Evaporation Sub-model and Simulation of Multiple Droplet Impingement in Volume of Fluid Method

NASA Astrophysics Data System (ADS)

Potham, Sathya Prasad

Droplet collision and impingement on a substrate are widely observed phenomenon in many applications like spray injection of Internal Combustion Engines, spray cooling, spray painting and atomizers used in propulsion applications. Existing Lagrangian models do not provide a comprehensive picture of the outcome of these events and may involve model constants requiring experimental data for validation. Physics based models like Volume of Fluid (VOF) method involve no parametric tuning and are more accurate. The aim of this thesis is to extend the basic VOF method with an evaporation sub-model and implement in an open source Computational Fluid Dynamics (CFD) software, OpenFOAM. The new model is applied to numerically study the evaporation of spherical n-heptane droplets impinging on a hot wall at atmospheric pressure and a temperature above the Leidenfrost temperature. An additional vapor phase is introduced apart from the liquid and gas phases to understand the mixing and diffusion of vapor and gas phases. The evaporation model is validated quantitatively and qualitatively with fundamental problems having analytical solutions and published results. The effect of droplet number and arrangement on evaporation is studied by three cases with one (Case 1), two (Case 2) and four (Case 3) droplets impinging on hot wall in film boiling regime at a fixed temperature of wall and a constant non-dimensional distance between droplets. Droplet lift and spread, surface temperature, heat transfer, and evaporation rate are examined. It was observed that more liquid mass evaporated in Case 1 compared to the other cases. Droplet levitation begins early in Case 1 and very high levitation observed was partially due to contraction of its shape from elongated to a more circular form. Average surface temperature was also considerably reduced in Case 1 due to high droplet levitation.

A denuder-impinger system with in situ derivatization followed by gas chromatography-mass spectrometry for the determination of gaseous iodine-containing halogen species.

PubMed

Huang, Ru-Jin; Hoffmann, Thorsten

2008-11-14

Reactive iodine species have been suggested to play an important role in the atmosphere (e.g. tropospheric ozone depletion, coastal new particle formation). However, there still exist major uncertainties about their atmospheric chemistry, mostly due to the lack of analytical approaches for the accurate speciation of certain key compounds. In this study, 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated denuder proved to be suitable for the differentiation between gaseous interhalogens (iodine monochloride (ICl), iodine monobromide (IBr)) and molecular iodine (I2) based on a selective collection/derivatization method. The results of the denuder sampling were compared with the results of impinger sampling in water, methanol and carbon tetrachloride solutions of 1,3,5-TMB. ICl and IBr are converted into 1-iodo-2,4,6-trimethoxybenzene (1-iodo-2,4,6-TMB) and 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB), respectively, in the denuder systems. The respective collection efficiency is 99.2% for ICl and 92.6% for IBr, at 500mLmin(-1) gas flow rate. The collection efficiency for I2 is lower than 1% in the same denuder system, but significantly increases to about 90% in the aqueous 1,3,5-TMB loaded impinger. The denuder-impinger coupled system was then used to differentiate and to collect the ICl, IBr and I2 gas mixtures, followed by gas chromatography-ion trap mass spectrometry (GC-MS) determination. The precision of the method is in general better than 9.1%. The parameters affecting denuder operation including sampling flow rate, sampling duration, and relative humidity have been evaluated. The presented method provides an attractive protocol for iodine species analysis for atmospheric chemistry research.

Analytical and experimental studies of impinging liquid jets

NASA Technical Reports Server (NTRS)

Ryan, H. M.; Anderson, W. E.; Pal, S.; Santoro, R. J.

1994-01-01

Impinging injectors are a common type of injector used in liquid propellant rocket engines and are typically used in engines where both propellants are injected as a liquid, e.g., engines using LOX/hydrocarbon and storable propellant combinations. The present research program is focused on providing the requisite fundamental understanding associated with impinging jet injectors for the development of an advanced a priori combustion stability design analysis capability. To date, a systematic study of the atomization characteristics of impinging liquid jets under cold-flow conditions have been completed. Effects of orifice diameter, impingement angle, pre-impingement length, orifice length-to-diameter ratio, fabrication procedure, jet flow condition and jet velocity under steady and oscillating, and atmospheric- and high-pressure environments have been investigated. Results of these experimental studies have been compared to current models of sheet breakup and drop formation. In addition, the research findings have been scrutinized to provide a fundamental explanation for a proven empirical correlation used in the design of stable impinging injector-based rocket engines.

Ankle impingement syndromes: an imaging review

PubMed Central

Tafur, Monica; Ahmed, Sonya S; Huang, Brady K; Chang, Eric Y

2017-01-01

Ankle impingement syndromes encompass a broad spectrum of post-traumatic and chronic degenerative changes that present with pain on specific movements about the ankle joint. Both amateur and professional athletes are disproportionately affected by these conditions, and while conservative measures can potentially treat an impingement syndrome, definitive therapy is often alleviated surgically. Imaging (including conventional radiography, ultrasound, CT and MRI) plays an invaluable role in the diagnosis and pre-surgical work-up. An anatomically based classification system is useful in these syndromes, as the aetiology, sites of pathology and preferred treatment methods are similarly based on anatomic locations about the ankle. This review focuses on the anatomic locations, pathophysiology, imaging considerations and brief discussion of therapies for each of the major anatomic ankle impingement syndromes. PMID:27885856

The anti-corrosion behavior under multi-factor impingement of Hastelloy C22 coating prepared by multilayer laser cladding

NASA Astrophysics Data System (ADS)

Chen, Lin; Bai, Shu-Lin

2018-04-01

Hastelloy C22 coating was prepared on substrate of Q235 steel by high power multilayer laser cladding. The microstructure, hardness and anti-corrosion properties of coating were investigated. The corrosion tests in 3.5% NaCl solution were carried out with variation of impingement angle and velocity, and vibration frequency of sample. The microstructure of coating changes from equiaxed grain at the top surface to dendrites oriented at an angle of 60° to the substrate inside the coating. The corrosion rate of coating increases with the increase of impingement angle and velocity, and vibrant frequency of sample. Corrosion mechanisms relate to repassivation and depassivation of coating according to electrochemical measurements. Above results show that multilayer laser cladding can endow Hastelloy C22 coating with fine microstructures, high hardness and good anti-corrosion performances.

Controllable synthesis of (NH4)Fe2(PO4)2(OH)·2H2O using two-step route: Ultrasonic-intensified impinging stream pre-treatment followed by hydrothermal treatment.

PubMed

Dong, Bin; Li, Guang; Yang, Xiaogang; Chen, Luming; Chen, George Z

2018-04-01

(NH 4 )Fe 2 (PO 4 ) 2 (OH)·2H 2 O samples with different morphology are successfully synthesized via two-step synthesis route - ultrasonic-intensified impinging stream pre-treatment followed by hydrothermal treatment (UIHT) method. The effects of the adoption of ultrasonic-intensified impinging stream pre-treatment, reagent concentration (C), pH value of solution and hydrothermal reaction time (T) on the physical and chemical properties of the synthesised (NH 4 )Fe 2 (PO 4 ) 2 (OH)·2H 2 O composites and FePO 4 particles were systematically investigated. Nano-seeds were firstly synthesized using the ultrasonic-intensified T-mixer and these nano-seeds were then transferred into a hydrothermal reactor, heated at 170 °C for 4 h. The obtained samples were characterized by utilising XRD, BET, TG-DTA, SEM, TEM, Mastersizer 3000 and FTIR, respectively. The experimental results have indicated that the particle size and morphology of the obtained samples are remarkably affected by the use of ultrasonic-intensified impinging stream pre-treatment, hydrothermal reaction time, reagent concentration, and pH value of solution. When such (NH 4 )Fe 2 (PO 4 ) 2 (OH)·2H 2 O precursor samples were transformed to FePO 4 products after sintering at 650 °C for 10 h, the SEM images have clearly shown that both the precursor and the final product still retain their monodispersed spherical microstructures with similar particle size of about 3 μm when the samples are synthesised at the optimised condition. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigation of Particle Deposition in Internal Cooling Cavities of a Nozzle Guide Vane

NASA Astrophysics Data System (ADS)

Casaday, Brian Patrick

Experimental and computational studies were conducted regarding particle deposition in the internal film cooling cavities of nozzle guide vanes. An experimental facility was fabricated to simulate particle deposition on an impingement liner and upstream surface of a nozzle guide vane wall. The facility supplied particle-laden flow at temperatures up to 1000°F (540°C) to a simplified impingement cooling test section. The heated flow passed through a perforated impingement plate and impacted on a heated flat wall. The particle-laden impingement jets resulted in the buildup of deposit cones associated with individual impingement jets. The deposit growth rate increased with increasing temperature and decreasing impinging velocities. For some low flow rates or high flow temperatures, the deposit cones heights spanned the entire gap between the impingement plate and wall, and grew through the impingement holes. For high flow rates, deposit structures were removed by shear forces from the flow. At low temperatures, deposit formed not only as individual cones, but as ridges located at the mid-planes between impinging jets. A computational model was developed to predict the deposit buildup seen in the experiments. The test section geometry and fluid flow from the experiment were replicated computationally and an Eulerian-Lagrangian particle tracking technique was employed. Several particle sticking models were employed and tested for adequacy. Sticking models that accurately predicted locations and rates in external deposition experiments failed to predict certain structures or rates seen in internal applications. A geometry adaptation technique was employed and the effect on deposition prediction was discussed. A new computational sticking model was developed that predicts deposition rates based on the local wall shear. The growth patterns were compared to experiments under different operating conditions. Of all the sticking models employed, the model based on wall shear, in conjunction with geometry adaptation, proved to be the most accurate in predicting the forms of deposit growth. It was the only model that predicted the changing deposition trends based on flow temperature or Reynolds number, and is recommended for further investigation and application in the modeling of deposition in internal cooling cavities.

Heat transfer between a heated plate and an impinging transient diesel spray

NASA Astrophysics Data System (ADS)

Arcoumanis, C.; Chang, J.-C.

1993-12-01

An experimental investigation was performed to determine the heat-transfer distribution in the vicinity of a transient diesel spray impinging on a heated flat plate. The spray prior to impingement was characterised in terms of simultaneous droplet sizes and velocities by phase-Doppler anemometry while during its impingement on the plate, which was heated at temperatures between 150 205°C, the instantaneous surface temperature and associated rates of wall heat transfer were monitored by fast response thermocouples. The parameters examined in this work included the distance between the nozzle and the wall surface, the radial distance from the impingement point, the injection frequency, the injected volume and the pre-impingement wall temperature. The results showed that the wall heat transfer rates are dependent on the spray characteristics prior to impingement; the higher the “velocity of arrival” of the droplet is, the higher the heat transfer. A correlation was thus developed for the instantaneous and spatially-resolved spray/wall heat transfer based on experimentally-determined Nusselt, Reynolds, Prandtl and Weber numbers over a wide range of test conditions.

Kinematics and dynamics of green water on a fixed platform in a large wave basin in focusing wave and random wave conditions

NASA Astrophysics Data System (ADS)

Chuang, Wei-Liang; Chang, Kuang-An; Mercier, Richard

2018-06-01

Green water kinematics and dynamics due to wave impingements on a simplified geometry, fixed platform were experimentally investigated in a large, deep-water wave basin. Both plane focusing waves and random waves were employed in the generation of green water. The focusing wave condition was designed to create two consecutive plunging breaking waves with one impinging on the frontal vertical wall of the fixed platform, referred as wall impingement, and the other directly impinging on the deck surface, referred as deck impingement. The random wave condition was generated using the JONSWAP spectrum with a significant wave height approximately equal to the freeboard. A total of 179 green water events were collected in the random wave condition. By examining the green water events in random waves, three different flow types are categorized: collapse of overtopping wave, fall of bulk water, and breaking wave crest. The aerated flow velocity was measured using bubble image velocimetry, while the void fraction was measured using fiber optic reflectometry. For the plane focusing wave condition, measurements of impact pressure were synchronized with the flow velocity and void fraction measurements. The relationship between the peak pressures and the pressure rise times is examined. For the high-intensity impact in the deck impingement events, the peak pressures are observed to be proportional to the aeration levels. The maximum horizontal velocities in the green water events in random waves are well represented by the lognormal distribution. Ritter's solution is shown to quantitatively describe the green water velocity distributions under both the focusing wave condition and the random wave condition. A prediction equation for green water velocity distribution under random waves is proposed.

High temperature decomposition of hydrogen peroxide

NASA Technical Reports Server (NTRS)

Parrish, Clyde F. (Inventor)

2005-01-01

Nitric oxide (NO) is oxidized into nitrogen dioxide (NO2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydroperoxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

High Temperature Decomposition of Hydrogen Peroxide

NASA Technical Reports Server (NTRS)

Parrish, Clyde F. (Inventor)

2004-01-01

Nitric oxide (NO) is oxidized into nitrogen dioxide (NO2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydropemxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

Improved aqueous scrubber for collection of soluble atmospheric trace gases

NASA Technical Reports Server (NTRS)

Cofer, W. R., III; Talbot, R. W.; Collins, V. G.

1985-01-01

A new concentration technique for the extraction and enrichment of water-soluble atmospheric trace gases has been developed. The gas scrubbing technique efficiently extracts soluble gases from a large volume flow rate of air sample into a small volume of refluxed trapping solution. The gas scrubber utilizes a small nebulizing nozzle that mixes the incoming air with an aqueous extracting solution to form an air/droplet mist. The mist provides excellent interfacial surface areas for mass transfer. The resulting mist sprays upward through the reaction chamber until it impinges upon a hydrophobic membrane that virtually blocks the passage of droplets but offers little resistance to the existing gas flow. Droplets containing the scrubbed gases coalesce on the membrane and drip back into the reservoir for further refluxing. After a suitable concentration period, the extracting solution containing the analyte can be withdrawn for analysis. The nebulization-reflex concentration technique is more efficient (maximum flow of gas through the minimum volume of extractant) than conventional bubbler/impinger gas extraction techniques and is offered as an alternative method.

Atmospheric H2O2 measurement: comparison of cold trap method with impinger bubbling method

NASA Technical Reports Server (NTRS)

Sakugawa, H.; Kaplan, I. R.

1987-01-01

Collection of atmospheric H2O2 was performed by a cold trap method using dry ice-acetone as the refrigerant. The air was drawn by a pump into a glass gas trap immersed in the dry ice-acetone slush in a dewar flask at a flow rate of 2.5 l min-1 for approximately 2 h. Collection efficiency was > 99% and negligible interferences by O3, SO2 or organic matter with the collected H2O2 in the trap were observed. This method was compared with the air impinger bubbling method which has been previously described (Kok et al., 1978a, b, Envir. Sci. Technol. 12, 1072-1080). The measured total peroxide (H2O2 + organic peroxide) values in a series of aim samples collected by the impinger bubbling method (0.06-3.7 ppb) were always higher than those obtained by the cold trap method (0.02-1.2 ppb). Laboratory experiments suggest that the difference in values between the two methods probably results from the aqueous phase generation of H2O2 and organic peroxide in the impinger solution by a reaction of atmospheric O3 with olefinic and aromatic compounds. If these O3-organic compound reactions which occur in the impinger also occur in aqueous droplets in the atmosphere, the process could be very important for aqueous phase generation of H2O2 in clouds and rainwater.

The sagittal stem alignment and the stem version clearly influence the impingement-free range of motion in total hip arthroplasty: a computer model-based analysis.

PubMed

Müller, Michael; Duda, Georg; Perka, Carsten; Tohtz, Stephan

2016-03-01

The component alignment in total hip arthroplasty influences the impingement-free range of motion (ROM). While substantiated data is available for the cup positioning, little is known about the stem alignment. Especially stem rotation and the sagittal alignment influence the position of the cone in relation to the edge of the socket and thus the impingement-free functioning. Hence, the question arises as to what influence do these parameters have on the impingement-free ROM? With the help of a computer model the influence of the sagittal stem alignment and rotation on the impingement-free ROM were investigated. The computer model was based on the CT dataset of a patient with a non-cemented THA. In the model the stem version was set at 10°/0°/-10° and the sagittal alignment at 5°/0°/-5°, which resulted in nine alternative stem positions. For each position, the maximum impingement-free ROM was investigated. Both stem version and sagittal stem alignment have a relevant influence on the impingement-free ROM. In particular, flexion and extension as well as internal and external rotation capability present evident differences. In the position intervals of 10° sagittal stem alignment and 20° stem version a difference was found of about 80° in the flexion and 50° in the extension capability. Likewise, differences were evidenced of up to 72° in the internal and up to 36° in the external rotation. The sagittal stem alignment and the stem torsion have a relevant influence on the impingement-free ROM. To clarify the causes of an impingement or accompanying problems, both parameters should be examined and, if possible, a combined assessment of these factors should be made.

Current standard rules of combined anteversion prevent prosthetic impingement but ignore osseous contact in total hip arthroplasty.

PubMed

Weber, Markus; Woerner, Michael; Craiovan, Benjamin; Voellner, Florian; Worlicek, Michael; Springorum, Hans-Robert; Grifka, Joachim; Renkawitz, Tobias

2016-12-01

In this prospective study of 135 patients undergoing cementless total hip arthroplasty (THA) we asked whether six current definitions of combined anteversion prevent impingement and increase postoperative patient individual impingement-free range-of-motion (ROM). Implant position was measured by an independent, external institute on 3D-CT performed six weeks post-operatively. Post-operative ROM was calculated using a CT-based algorithm detecting osseous and/or prosthetic impingement by virtual hip movement. Additionally, clinical ROM was evaluated pre-operatively and one-year post-operatively by a blinded observer. Combined component position of cup and stem according to the definitions of Ranawat, Widmer, Dorr, Hisatome and Yoshimine inhibited prosthetic impingement in over 90 %, while combined osseous and prosthetic impingement still occurred in over 40 % of the cases. The recommendations by Jolles, Widmer, Dorr, Yoshimine and Hisatome enabled higher flexion (p ≤ 0.001) and internal rotation (p ≤ 0.006). Clinically, anteversion rules of Widmer and Yoshimine provided one-year post-operatively statistically but not clinically relevant higher internal rotation (p ≤0.034). Standard rules of combined anteversion detect prosthetic but fail to prevent combined osseous and prosthetic impingement in THA. Future models will have to account for the patient-individual anatomic situation to ensure impingement-free ROM.

High temperature decomposition of hydrogen peroxide

NASA Technical Reports Server (NTRS)

Parrish, Clyde F. (Inventor)

2004-01-01

Nitric oxide (NO) is oxidized into nitrogen dioxide (NO.sub.2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydroperoxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

High temperature decomposition of hydrogen peroxide

NASA Technical Reports Server (NTRS)

Parrish, Clyde F. (Inventor)

2011-01-01

Nitric oxide (NO) is oxidized into nitrogen dioxide (NO.sub.2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydroperoxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

Subspine impingement: 2 case reports of a previously unreported cause of instability in total hip arthroplasty.

PubMed

Davidovitch, Roy I; DelSole, Edward M; Vigdorchik, Jonathan M

2016-03-23

Instability is a common cause of revision hip arthroplasty and is frequently due to improper component placement and subsequent component impingement. Impingement of the greater trochanter upon the anterior inferior iliac spine (AIIS) has been described as a cause of symptomatic femoroacetabular impingement (FAI), but has never been described as a cause of instability following total hip arthroplasty (THA). We present 2 cases of patients undergoing THA. Each patient was evaluated preoperatively and found to have a prominent AIIS, which was concerning due to it overhanging the anterolateral acetabular lip. Both patients had intraoperative posterior instability of their THA, the cause of which was determined to be impingement of the greater trochanter upon a prominent AIIS. Open resection of the AIIS was performed with subsequent resolution of impingement. AIIS impingement has been reported as a cause of symptomatic FAI. In these case reports, open or arthroscopic resection of the AIIS resulted in resolution of symptoms. Morphologically distinct subtypes of the AIIS have been previously described based upon computed tomography, and some subtypes are associated with a high risk of impingement in the native hip. No previous studies have described this phenomenon in the setting of THA. Instability is a common cause of revision THA. Impingement of the greater trochanter upon a prominent AIIS is a previously unreported cause of THA instability which can be addressed with intraoperative resection of the AIIS with good result.

A case study for removal of sulphur-di-oxide from exhaust flue gases at thermal power plant, Rajasthan (India).

PubMed

Sharma, Rashmi; Acharya, Shveta; Sharma, Arun Kumar

2011-01-01

The aim of this study is to reduce the percent SO2 in environment and to produce a byproduct with SO2, to control air pollution. The present work envisages a situation that compares the efficiency of three different reagents, viz. sodium hydroxide, calcium hydroxide and waste product of water treatment plant containing CaO in removal of SO2 that would be generated in this situation. Various parameters were also observed with variation involving percent concentration of reactants, pH of the solution, time for reaction , temperature of solution and flow of flue gas in impingers. Pet coke with lime stone is being used for power generation in power plant during the experiment, the pet coke having 6% sulphur resulting in emission of SO2. Hence experiments have been conducted to trap these gases to produce sulphates. Waste product of water treatment plant, calcium hydroxide, and sodium hydroxide in various permutation and combination have been used with control flow by SO2 monitoring kit for preparation of calcium sulphate and sodium sulphate. Thus sodium hydroxide turned out to be better as compared to calcium hydroxide and sludge. It is also concluded that pH of the solution should be alkaline for good absorption of SO2 and maximum absorption of SO2 found in direct passing of SO2 in impinger as compared to indirect passing of SO2 in impingers. Good absorption of SO2 found at temperature range between 20-25 degrees C and it seems to be optimum. Maximum recovery of SO2 was obtained when the reaction took place for long time period.

Impingement thermal performance of perforated circular pin-fin heat sinks

NASA Astrophysics Data System (ADS)

Wen, Mao-Yu; Yeh, Cheng-Hsiung

2018-04-01

The study presents the experimental information on heat transfer performance of jet impingement cooling on circular pin- fin heat sinks with/without a hollow perforated base plate. Smoke flow visualization is also used to investigate the behavior of the complicated flow phenomena of the present heat sinks for this impingement cooling. The effects of flow Reynolds numbers (3458≤Re≤11,526), fin height, the geometry of the heat sinks (with/without a hollow perforated base plate), and jet-to-test heat sink placement (1 ≤ H/ d≤16) are examined. In addition, empirical correlation to estimate the heat transfer coefficient was also developed.

Side wall cooling for nozzle segments for a gas turbine

DOEpatents

Burdgick, Steven Sebastian

2002-01-01

A nozzle vane segment includes outer and inner band portions with a vane extending therebetween and defining first and second cavities separated by an impingement plate for flowing cooling medium for impingement cooling of nozzle side walls. The side wall of each nozzle segment has an undercut region. The impingement plate has an inturned flange with a plurality of openings. Cooling inserts or receptacles having an open end are received in the openings and the base and side walls of the receptacles have apertures for receiving cooling medium from the first cavity and directing the cooling medium for impingement cooling of the side wall of the nozzle segment and a portion of the nozzle wall.

Conformal mapping technique for two-dimensional porous media and jet impingement heat transfer

NASA Technical Reports Server (NTRS)

Siegel, R.

1974-01-01

Transpiration cooling and liquid metals both provide highly effective heat transfer. Using Darcy's law in porous media and the inviscid approximation for liquid metals, the local fluid velocity in these flows equals the gradient of a potential. The energy equation and flow region are simplified when transformed into potential plane coordinates. In these coordinates, the present problems are reduced to heat conduction solutions which are mapped into the physical geometry. Results are obtained for a porous region with simultaneously prescribed surface temperature and heat flux, heat transfer in a two-dimensional porous bed, and heat transfer for two liquid metal slot jets impinging on a heated plate.

Conformal mapping technique for two-dimensional porous media and jet impingement heat transfer

NASA Technical Reports Server (NTRS)

Siegel, R.

1973-01-01

Transpiration cooling and liquid metals both provide highly effective heat transfer. Using Darcy's law in porous media, and the inviscid approximation for liquid metals, the local fluid velocity in these flows equals the gradient of a potential, The energy equation and flow region are simplified when transformed into potential plane coordinates. In these coordinates the present problems are reduced to heat conduction solutions which are mapped into the physical geometry. Results are obtained for a porous region with simultaneously prescribed surface temperature and heat flux, heat transfer in a two-dimensional porous bed, and heat transfer for two liquid metal slot jets impinging on a heated plate.

Numerical modeling of the early interaction of a planar shock with a dense particle field

NASA Astrophysics Data System (ADS)

Regele, Jonathan; Blanquart, Guillaume

2011-11-01

Dense compressible multiphase flows are of interest for multiphase turbomachinary and energetic material detonations. Still, there is little understanding of the detailed interaction mechanisms between shock waves and dense (particle volume fraction αd > 0 . 001) particle fields. A recent experimental study [Wagner et al, AIAA Aero. Sci., Orlando, 2011-188] has focused on the impingement of a planar shock wave on a dense particle curtain. In the present work, numerical solutions of the Euler equations in one and two dimensions are performed for a planar shock wave impinging on a fixed particle curtain and are compared to the experimental data for early times. Comparison of the one- and two-dimensional results demonstrate that the one-dimensional description captures the large scale flow behavior, but is inadequate to capture all the details observed in the experiments. The two-dimensional solutions are shown to reproduce the experimentally observed flow structures and provide insight into how these details originate.

Statistics of fully turbulent impinging jets

NASA Astrophysics Data System (ADS)

Wilke, Robert; Sesterhenn, Jörn

2017-08-01

Direct numerical simulations of sub- and supersonic impinging jets with Reynolds numbers of 3300 and 8000 are carried out to analyse their statistical properties. The influence of the parameters Mach number, Reynolds number and ambient temperature on the mean velocity and temperature fields are studied. For the compressible subsonic cold impinging jets into a heated environment, different Reynolds analogies are assesses. It is shown, that the (original) Reynolds analogy as well as the Chilton Colburn analogy are in good agreement with the DNS data outside the impinging area. The generalised Reynolds analogy (GRA) and the Crocco-Busemann relation are not suited for the estimation of the mean temperature field based on the mean velocity field of impinging jets. Furthermore, the prediction of fluctuating temperatures according to the GRA fails. On the contrary, the linear relation between thermodynamic fluctuations of entropy, density and temperature as suggested by Lechner et al. (2001) can be confirmed for the entire wall jet. The turbulent heat flux and Reynolds stress tensor are analysed and brought into coherence with the primary and secondary ring vortices of the wall jet. Budget terms of the Reynolds stress tensor are given as data base for the improvement of turbulence models.

Use of conventional fishery models to assess entrainment and impingement of three Lake Michigan fish species

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

Jensen, A.L.; Spigarelli, J.A.; Thommes, M.M.

1982-01-01

Two conventional fishery stock assessment models, the surplus-production model and the dynamic-pool model, were applied to assess the impacts of water withdrawals by electricity-generating plants, industries, and municipalities on the standing stocks and yields of alewife Alosa pseudoharengus, rainbow smelt Osmerus mordax, and yellow perch Perca flavescens in Lake Michigan. Impingement and entrainment estimates were based on data collected at 15 power plants. The surplus-production model was fitted to the three populations with catch and effort data from the commercial fisheries. Dynamic-pool model parameters were estimated from published data. The numbers entrained and impinged are large, but the proportions ofmore » the standing stocks impinged and the proportions of the eggs and larvae entrained are small. The reductions in biomass of the stocks and in maximum sustainable yields are larger than the proportions impinged. The reductions in biomass, based on 1975 data and an assumed full water withdrawal, are 2.86% for alewife, 0.76% for rainbow smelt, and 0.28% for yellow perch. Fishery models are an economical means of impact assessment in situations where catch and effort data are available for estimation of model parameters.« less

An exact solution of a simplified two-phase plume model. [for solid propellant rocket

NASA Technical Reports Server (NTRS)

Wang, S.-Y.; Roberts, B. B.

1974-01-01

An exact solution of a simplified two-phase, gas-particle, rocket exhaust plume model is presented. It may be used to make the upper-bound estimation of the heat flux and pressure loads due to particle impingement on the objects existing in the rocket exhaust plume. By including the correction factors to be determined experimentally, the present technique will provide realistic data concerning the heat and aerodynamic loads on these objects for design purposes. Excellent agreement in trend between the best available computer solution and the present exact solution is shown.

Measurement of impinging butane flame using combined optical system with digital speckle tomography

NASA Astrophysics Data System (ADS)

Ko, Han Seo; Ahn, Seong Soo; Kim, Hyun Jung

2011-11-01

Three-dimensional density distributions of an impinging and eccentric flame were measured experimentally using a combined optical system with digital speckle tomography. In addition, a three-dimensional temperature distribution of the flame was reconstructed from an ideal gas equation based on the reconstructed density data. The flame was formed by the ignition of premixed butane/air from air holes and impinged upward against a plate located 24 mm distance from the burner nozzle. In order to verify the reconstruction process for the experimental measurements, numerically synthesized phantoms of impinging and eccentric flames were derived and reconstructed using a developed three-dimensional multiplicative algebraic reconstruction technique (MART). A new scanning technique was developed for the accurate analysis of speckle displacements necessary for investigating the wall jet regions of the impinging flame at which a sharp variation of the flow direction and pressure gradient occur. The reconstructed temperatures by the digital speckle tomography were applied to the boundary condition for numerical analysis of a flame impinged plate. Then, the numerically calculated temperature distribution of the upper side of the flame impinged plate was compared to temperature data taken by an infrared camera. The absolute average uncertainty between the numerical and infrared camera data was 3.7%.

Particle-Laden Liquid Jet Impingement on a Moving Substrate

NASA Astrophysics Data System (ADS)

Rahmani, Hatef; Green, Sheldon

2017-11-01

The impingement of high-speed jets on a moving substrate is salient to a number of industrial processes such as surface coating in the railroad industry. The particular jet fluids studied were dilute suspensions of neutrally buoyant particles in water-glycerin solutions. At these low particle concentrations, the suspensions have Newtonian fluid viscosity. A variety of jet and surface velocities, solution properties, nozzle diameters, mean particle sizes, and volume fractions were studied. It was observed that for jets with very small particles, addition of solids to the jet enhances deposition and postpones splash relative to a particle-free water-glycerin solution with the same viscosity. In contrast, jets with larger particles in suspension were more prone to splash than single phase jets of the same viscosity. It is speculated that the particle diameter, relative to the lamella thickness, is the key parameter to determine whether splash is suppressed or enhanced. An existing splash model for single phase liquid jets was found to be in good agreement with the experimental results, provided that the single fitting parameter in that model is a function of the particle size, volume fraction, and surface roughness.

Stereo-PIV study of flow inside an eye under cataract surgery

NASA Astrophysics Data System (ADS)

Sakakibara, Jun; Yamashita, Masaki; Kobayashi, Tatsuya; Kaji, Yuichi; Oshika, Tetsuro

2012-04-01

We measured velocity distributions in the anterior chamber of porcine eyes under simulated cataract surgery using stereoscopic particle image velocimetry (stereo-PIV). The surface of the cornea was detected based on the images of laser-induced fluorescent light emitted from fluorescent dye solution introduced in a posterior chamber. A coaxial phacoemulsification procedure was simulated with standard size (standard coaxial phacoemulsification) and smaller (micro coaxial phacoemulsification) surgical instruments. In both cases, an asymmetric flow rate of irrigation was observed, although both irrigation ports had the same dimensions prior to insertion into the eye. In cases where the tip of the handpiece was placed farther away from the top of the cornea, i.e., closer to the crystalline lens, direct impingement of irrigation flow onto the cornea surface was avoided and the flow turned back toward the handpiece along the surface of the corneal endothelium. Viscous shear stress on the corneal endothelium was computed based on the measured mean velocity distribution. The maximum shear stress for most cases exceeded 0.1 Pa, which is comparable to the shear stress that caused detachment of the corneal endothelial cells reported by Kaji et al. in Cornea 24:S55-S58, (2005). When direct impingement of the irrigation flow was avoided, the shear stress was reduced considerably.

Study of Plume Impingement Effects in the Lunar Lander Environment

NASA Technical Reports Server (NTRS)

Marichalar, Jeremiah; Prisbell, A.; Lumpkin, F.; LeBeau, G.

2010-01-01

Plume impingement effects from the descent and ascent engine firings of the Lunar Lander were analyzed in support of the Lunar Architecture Team under the Constellation Program. The descent stage analysis was performed to obtain shear and pressure forces on the lunar surface as well as velocity and density profiles in the flow field in an effort to understand lunar soil erosion and ejected soil impact damage which was analyzed as part of a separate study. A CFD/DSMC decoupled methodology was used with the Bird continuum breakdown parameter to distinguish the continuum flow from the rarefied flow. The ascent stage analysis was performed to ascertain the forces and moments acting on the Lunar Lander Ascent Module due to the firing of the main engine on take-off. The Reacting and Multiphase Program (RAMP) method of characteristics (MOC) code was used to model the continuum region of the nozzle plume, and the Direct Simulation Monte Carlo (DSMC) Analysis Code (DAC) was used to model the impingement results in the rarefied region. The ascent module (AM) was analyzed for various pitch and yaw rotations and for various heights in relation to the descent module (DM). For the ascent stage analysis, the plume inflow boundary was located near the nozzle exit plane in a region where the flow number density was large enough to make the DSMC solution computationally expensive. Therefore, a scaling coefficient was used to make the DSMC solution more computationally manageable. An analysis of the effectiveness of this scaling technique was performed by investigating various scaling parameters for a single height and rotation of the AM. Because the inflow boundary was near the nozzle exit plane, another analysis was performed investigating three different inflow contours to determine the effects of the flow expansion around the nozzle lip on the final plume impingement results.

Assessment of congruence and impingement of the hip joint in professional ballet dancers: a motion capture study.

PubMed

Charbonnier, Caecilia; Kolo, Frank C; Duthon, Victoria B; Magnenat-Thalmann, Nadia; Becker, Christoph D; Hoffmeyer, Pierre; Menetrey, Jacques

2011-03-01

Early hip osteoarthritis in dancers could be explained by femoroacetabular impingements. However, there is a lack of validated noninvasive methods and dynamic studies to ascertain impingement during motion. Moreover, it is unknown whether the femoral head and acetabulum are congruent in typical dancing positions. The practice of some dancing movements could cause a loss of hip joint congruence and recurrent impingements, which could lead to early osteoarthritis. Descriptive laboratory study. Eleven pairs of female dancer's hips were motion captured with an optical tracking system while performing 6 different dancing movements. The resulting computed motions were applied to patient-specific hip joint 3-dimensional models based on magnetic resonance images. While visualizing the dancer's hip in motion, the authors detected impingements using computer-assisted techniques. The range of motion and congruence of the hip joint were also quantified in those 6 recorded dancing movements. The frequency of impingement and subluxation varied with the type of movement. Four dancing movements (développé à la seconde, grand écart facial, grand écart latéral, and grand plié) seem to induce significant stress in the hip joint, according to the observed high frequency of impingement and amount of subluxation. The femoroacetabular translations were high (range, 0.93 to 6.35 mm). For almost all movements, the computed zones of impingement were mainly located in the superior or posterosuperior quadrant of the acetabulum, which was relevant with respect to radiologically diagnosed damaged zones in the labrum. All dancers' hips were morphologically normal. Impingements and subluxations are frequently observed in typical ballet movements, causing cartilage hypercompression. These movements should be limited in frequency. The present study indicates that some dancing movements could damage the hip joint, which could lead to early osteoarthritis.

Impingement following anterior cruciate ligament reconstruction: comparing the direct versus indirect femoral tunnel position.

PubMed

van der List, J P; Zuiderbaan, H A; Nawabi, D H; Pearle, A D

2017-05-01

During anterior cruciate ligament (ACL) reconstruction, authors have suggested inserting the femoral tunnel at the biomechanically relevant direct fibres, but this higher position can cause more impingement. Therefore, we aimed to assess ACL graft impingement at the femoral notch for ACL reconstruction at both the direct and indirect tunnel positions. A virtual model was created for twelve cadaveric knees with computed tomography scanning in which a virtual graft was placed at direct and indirect tunnel positions of the anteromedial bundle (AM), posterolateral bundle (PL) or centre of the both bundles (C). In these six tunnel positions, the volume (mm 3 ) and mid-point location of impingement (°) were measured at different flexion angles. Generally, more impingement was seen with the indirect position compared with the direct position although this was only significant at 90° of flexion for the AM position (97 ± 28 vs. 76 ± 20 mm 3 , respectively; p = 0.046). The direct tunnel position impinged higher at the notch, whereas the indirect position impinged more towards the lateral wall, but this was only significant at 90° of flexion for the AM (24 ± 5° vs. 34 ± 4°, respectively; p < 0.001) and C position (34 ± 5° vs. 42 ± 5°, respectively; p = 0.003). In this cadaveric study, the direct tunnel position did not cause more impingement than the indirect tunnel position. Based on these results, graft impingement is not a limitation to reconstruct the femoral tunnel at the insertion of the biomechanically more relevant direct fibres.

Reproducible direct exposure environmental testing of metal-based magnetic media

NASA Technical Reports Server (NTRS)

Sides, Paul J.

1994-01-01

A flow geometry and flow rate for mixed flowing gas testing is proposed. Use of an impinging jet of humid polluted air can provide a uniform and reproducible exposure of coupons of metal-based magnetic media. Numerical analysis of the fluid flow and mass transfer in such as system has shown that samples confined within a distance equal to the nozzle radius on the surface of impingement are uniformly accessible to pollutants in the impinging gas phase. The critical factor is the nozzle height above the surface of impingement. In particular, the uniformity of exposure is less than plus/minus 2% for a volumetric flow rate of 1600 cm(exp 3)/minute total flow with the following specifications: For a one inch nozzle, the height of the nozzle opening above the stage should be 0.177 inches; for a 2 inch nozzle - 0.390 inches. Not only is the distribution uniform, but one can calculate the maximum delivery rate of pollutants to the samples for comparison with the observed deterioration.

Flow-based ammonia gas analyzer with an open channel scrubber for indoor environments.

PubMed

Ohira, Shin-Ichi; Heima, Minako; Yamasaki, Takayuki; Tanaka, Toshinori; Koga, Tomoko; Toda, Kei

2013-11-15

A robust and fully automated indoor ammonia gas monitoring system with an open channel scrubber (OCS) was developed. The sample gas channel dimensions, hydrophilic surface treatment to produce a thin absorbing solution layer, and solution flow rate of the OCS were optimized to connect the OCS as in-line gas collector and avoid sample humidity effects. The OCS effluent containing absorbed ammonia in sample gas was injected into a derivatization solution flow. Derivatization was achieved with o-phthalaldehyde and sulfite in pH 11 buffer solution. The product, 1-sulfonateisoindole, is detected with a home-made fluorescence detector. The limit of detection of the analyzer based on three times the standard deviation of baseline noise was 0.9 ppbv. Sample gas could be analyzed 40 times per hour. Furthermore, relative humidity of up to 90% did not interfere considerably with the analyzer. Interference from amines was not observed. The developed gas analysis system was calibrated using a solution-based method. The system was used to analyze ammonia in an indoor environment along with an off-site method, traditional impinger gas collection followed by ion chromatographic analysis, for comparison. The results obtained using both methods agreed well. Therefore, the developed system can perform on-site monitoring of ammonia in indoor environments with improved time resolution compared with that of other methods. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

Modeling of Heat Transfer and Ablation of Refractory Material Due to Rocket Plume Impingement

NASA Technical Reports Server (NTRS)

Harris, Michael F.; Vu, Bruce T.

2012-01-01

CR Tech's Thermal Desktop-SINDA/FLUINT software was used in the thermal analysis of a flame deflector design for Launch Complex 39B at Kennedy Space Center, Florida. The analysis of the flame deflector takes into account heat transfer due to plume impingement from expected vehicles to be launched at KSC. The heat flux from the plume was computed using computational fluid dynamics provided by Ames Research Center in Moffet Field, California. The results from the CFD solutions were mapped onto a 3-D Thermal Desktop model of the flame deflector using the boundary condition mapping capabilities in Thermal Desktop. The ablation subroutine in SINDA/FLUINT was then used to model the ablation of the refractory material.

Effect of a novel mobilization with movement procedure on anterolateral ankle impingement - A case report.

PubMed

Anandkumar, Sudarshan

2018-07-01

This case report describes a 50-year-old male who presented with right anterolateral ankle pain managed unsuccessfully with rest, medications, bracing, injection, physical therapy, and massage therapy. Clinical diagnosis of anterolateral ankle impingement was based on concordant symptom reproduction with palpatory tenderness and a positive lateral synovial impingement test. This case report is a potential first time description of the successful management of anterolateral ankle impingement utilizing a novel Mulligan's mobilization with movement procedure (consisting of internal rotation of the distal tibia) and taping with immediate improvements noted in pain, range of motion, and function. The patient was seen twice a week and was discharged after four treatment sessions. A follow-up after 4 months revealed that the patient was pain free and fully functional.

Neutron absorption detector

DOEpatents

Bell, Zane William [Oak Ridge, TN; Boatner, Lynn Allen [Oak Ridge, TN

2011-05-31

A method of detecting an activator, the method including impinging a receptor material that is not predominately water and lacks a photoluminescent material with an activator and generating Cherenkov effect light due to the activator impinging the receptor material. The method further including identifying a characteristic of the activator based on the light.

Application of precipitation methods for the production of water-insoluble drug nanocrystals: production techniques and stability of nanocrystals.

PubMed

Xia, Dengning; Gan, Yong; Cui, Fude

2014-01-01

This review focuses on using precipitation (bottom-up) method to produce water-insoluble drug nanocrystals, and the stability issues of nanocrystals. The precipitation techniques for production of ultra-fine particles have been widely researched for last few decades. In these techniques, precipitation of solute is achieved by addition of a non-solvent for solute called anti-solvent to decrease the solvent power for the solute dissolved in a solution. The anti-solvent can be water, organic solvents or supercritical fluids. In this paper, efforts have been made to review the precipitation techniques involving the anti-solvent precipitation by simple mixing, impinging jet mixing, multi-inlet vortex mixing, the using of high-gravity, ultrasonic waves and supercritical fluids. The key to the success of yielding stable nanocrystals in these techniques is to control the nucleation kinetics and particle growth through mixing during precipitation based on crystallization theories. The stability issues of the nanocrystals, such as sedimentation, Ostwald ripening, agglomeration and cementing of crystals, change of crystalline state, and the approaches to stabilizing nanocrystals are also discussed in detail.

Advanced Liquid Cooling for a Traction Drive Inverter Using Jet Impingement and Microfinned Enhanced Surfaces: Preprint

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

Waye, S. K.; Narumanchi, S.; Mihalic, M.

2014-08-01

Jet impingement on plain and micro-finned enhanced surfaces was compared to a traditional channel flow configuration. The jets provide localized cooling to areas heated by the insulated-gate bipolar transistor and diode devices. Enhanced microfinned surfaces increase surface area and thermal performance. Using lighter materials and designing the fluid path to manage pressure losses increases overall performance while reducing weight, volume, and cost. Powering four diodes in the center power module of the inverter and computational fluid dynamics (CFD) modeling was used to characterize the baseline as well as jet-impingement-based heat exchangers. CFD modeling showed the thermal performance improvements should holdmore » for a fully powered inverter. Increased thermal performance was observed for the jet-impingement configurations when tested at full inverter power (40 to 100 kW output power) on a dynamometer. The reliability of the jets and enhanced surfaces over time was also investigated. Experimentally, the junction-to- coolant thermal resistance was reduced by up to 12.5% for jet impingement on enhanced surfaces s compared to the baseline channel flow configuration. Base plate-to-coolant (convective) resistance was reduced by up to 37.0% for the jet-based configuration compared to the baseline, suggesting that while improvements to the cooling side reduce overall resistance, reducing the passive stack resistance may contribute to lowering overall junction-to-coolant resistance. Full inverter power testing showed reduced thermal resistance from the middle of the module baseplate to coolant of up to 16.5%. Between the improvement in thermal performance and pumping power, the coefficient of performance improved by up to 13% for the jet-based configuration.« less

High-speed visualization of fuel spray impingement in the near-wall region using a DISI injector

NASA Astrophysics Data System (ADS)

Kawahara, N.; Kintaka, K.; Tomita, E.

2017-02-01

We used a multi-hole injector to spray isooctane under atmospheric conditions and observed droplet impingement behaviors. It is generally known that droplet impact regimes such as splashing, deposition, or bouncing are governed by the Weber number. However, owing to its complexity, little has been reported on microscopic visualization of poly-dispersed spray. During the spray impingement process, a large number of droplets approach, hit, then interact with the wall. It is therefore difficult to focus on a single droplet and observe the impingement process. We solved this difficulty using high-speed microscopic visualization. The spray/wall interaction processes were recorded by a high-speed camera (Shimadzu HPV-X2) with a long-distance microscope. We captured several impinging microscopic droplets. After optimizing the magnification and frame rate, the atomization behaviors, splashing and deposition, were recorded. Then, we processed the images obtained to determine droplet parameters such as the diameter, velocity, and impingement angle. Based on this information, the critical threshold between splashing and deposition was investigated in terms of the normal and parallel components of the Weber number with respect to the wall. The results suggested that, on a dry wall, we should set the normal critical Weber number to 300.

Severe impingement of lumbar disc replacements increases the functional biological activity of polyethylene wear debris.

PubMed

Baxter, Ryan M; Macdonald, Daniel W; Kurtz, Steven M; Steinbeck, Marla J

2013-06-05

Wear, oxidation, and particularly rim impingement damage of ultra-high molecular weight polyethylene total disc replacement components have been observed following surgical revision. However, neither in vitro testing nor retrieval-based evidence has shown the effect(s) of impingement on the characteristics of polyethylene wear debris. Thus, we sought to determine (1) differences in polyethylene particle size, shape, number, or biological activity that correspond to mild or severe rim impingement and (2) in an analysis of all total disc replacements, regardless of impingement classification, whether there are correlations between the extent of regional damage and the characteristics of polyethylene wear debris. The extent of dome and rim damage was characterized for eleven retrieved polyethylene cores obtained at revision surgery after an average duration of implantation of 9.7 years (range, 4.6 to 16.1 years). Polyethylene wear debris was isolated from periprosthetic tissues with use of nitric acid and was imaged with use of environmental scanning electron microscopy. Subsequently, particle size, shape, number, biological activity, and chronic inflammation scores were determined. Grouping of particles by size ranges that represented high biological relevance (<0.1 to 1-μm particles), intermediate biological relevance (1 to 10-μm particles), and low biological relevance (>10-μm particles) revealed an increased volume fraction of particles in the <0.1 to 1-μm and 1 to 10-μm size ranges in the mild-impingement cohort as compared with the severe-impingement cohort. The increased volume fractions resulted in a higher specific biological activity per unit particle volume in the mild-impingement cohort than in the severe-impingement cohort. However, functional biological activity, which is normalized by particle volume (mm3/g of tissue), was significantly higher in the severe-impingement cohort. This increase was due to a larger volume of particles in all three size ranges. In both cohorts, the functional biological activity correlated with the chronic inflammatory response, and the extent of rim penetration positively correlated with increasing particle size, number, and functional biological activity. The results of this study suggest that severe rim impingement increases the production of biologically relevant particles from motion-preserving lumbar total disc replacement components. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Severe Impingement of Lumbar Disc Replacements Increases the Functional Biological Activity of Polyethylene Wear Debris

PubMed Central

Baxter, Ryan M.; MacDonald, Daniel W.; Kurtz, Steven M.; Steinbeck, Marla J.

2013-01-01

Background: Wear, oxidation, and particularly rim impingement damage of ultra-high molecular weight polyethylene total disc replacement components have been observed following surgical revision. However, neither in vitro testing nor retrieval-based evidence has shown the effect(s) of impingement on the characteristics of polyethylene wear debris. Thus, we sought to determine (1) differences in polyethylene particle size, shape, number, or biological activity that correspond to mild or severe rim impingement and (2) in an analysis of all total disc replacements, regardless of impingement classification, whether there are correlations between the extent of regional damage and the characteristics of polyethylene wear debris. Methods: The extent of dome and rim damage was characterized for eleven retrieved polyethylene cores obtained at revision surgery after an average duration of implantation of 9.7 years (range, 4.6 to 16.1 years). Polyethylene wear debris was isolated from periprosthetic tissues with use of nitric acid and was imaged with use of environmental scanning electron microscopy. Subsequently, particle size, shape, number, biological activity, and chronic inflammation scores were determined. Results: Grouping of particles by size ranges that represented high biological relevance (<0.1 to 1-μm particles), intermediate biological relevance (1 to 10-μm particles), and low biological relevance (>10-μm particles) revealed an increased volume fraction of particles in the <0.1 to 1-μm and 1 to 10-μm size ranges in the mild-impingement cohort as compared with the severe-impingement cohort. The increased volume fractions resulted in a higher specific biological activity per unit particle volume in the mild-impingement cohort than in the severe-impingement cohort. However, functional biological activity, which is normalized by particle volume (mm3/g of tissue), was significantly higher in the severe-impingement cohort. This increase was due to a larger volume of particles in all three size ranges. In both cohorts, the functional biological activity correlated with the chronic inflammatory response, and the extent of rim penetration positively correlated with increasing particle size, number, and functional biological activity. Conclusions: The results of this study suggest that severe rim impingement increases the production of biologically relevant particles from motion-preserving lumbar total disc replacement components. Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence. PMID:23780545

Calculation of oblique-shock-wave laminar-boundary-layer interaction on a flat plate

NASA Technical Reports Server (NTRS)

Goldberg, U.; Reshotko, E.

1980-01-01

A finite difference solution to the problem of the interaction between an impinging oblique shock wave and the laminar boundary layer on a flat plate is presented. The boundary layer equations coupled with the Prandtl-Meyer relation for the external flow are used to calculate the flow field. A method for the calculation of the separated flow region is presented and discussed. Comparisons between this theory and the experimental results of other investigators show fairly good agreement. Results are presented for the case of a cooled wall with an oncoming flow at Mach number 2.0 without and with suction. The results show that a small amount of suction greatly reduces the extent of the separated region in the vicinity of the shock impingement location.

Carbonyl compounds emitted by a diesel engine fuelled with diesel and biodiesel-diesel blends: Sampling optimization and emissions profile

NASA Astrophysics Data System (ADS)

Guarieiro, Lílian Lefol Nani; Pereira, Pedro Afonso de Paula; Torres, Ednildo Andrade; da Rocha, Gisele Olimpio; de Andrade, Jailson B.

Biodiesel is emerging as a renewable fuel, hence becoming a promising alternative to fossil fuels. Biodiesel can form blends with diesel in any ratio, and thus could replace partially, or even totally, diesel fuel in diesel engines what would bring a number of environmental, economical and social advantages. Although a number of studies are available on regulated substances, there is a gap of studies on unregulated substances, such as carbonyl compounds, emitted during the combustion of biodiesel, biodiesel-diesel and/or ethanol-biodiesel-diesel blends. CC is a class of hazardous pollutants known to be participating in photochemical smog formation. In this work a comparison was carried out between the two most widely used CC collection methods: C18 cartridges coated with an acid solution of 2,4-dinitrophenylhydrazine (2,4-DNPH) and impinger bottles filled in 2,4-DNPH solution. Sampling optimization was performed using a 2 2 factorial design tool. Samples were collected from the exhaust emissions of a diesel engine with biodiesel and operated by a steady-state dynamometer. In the central body of factorial design, the average of the sum of CC concentrations collected using impingers was 33.2 ppmV but it was only 6.5 ppmV for C18 cartridges. In addition, the relative standard deviation (RSD) was 4% for impingers and 37% for C18 cartridges. Clearly, the impinger system is able to collect CC more efficiently, with lower error than the C18 cartridge system. Furthermore, propionaldehyde was nearly not sampled by C18 system at all. For these reasons, the impinger system was chosen in our study. The optimized sampling conditions applied throughout this study were: two serially connected impingers each containing 10 mL of 2,4-DNPH solution at a flow rate of 0.2 L min -1 during 5 min. A profile study of the C1-C4 vapor-phase carbonyl compound emissions was obtained from exhaust of pure diesel (B0), pure biodiesel (B100) and biodiesel-diesel mixtures (B2, B5, B10, B20, B50, B75). The ΣCC of the emission concentrations were 20.5 ppmV for B0 and 15.7 ppmV for B100. When considering fuel blends, the measured ΣCC were 21.4 ppmV, 22.5 ppmV, 20.4 ppmV, 14.2 ppmV, 11.4 ppmV and 14.7 ppmV, respectively, for B2, B5, B10, B20, B50 and B75. Among the target CC, both formaldehyde and acetaldehyde were the major contributors to the observed total CC levels. Except for acrolein and formaldehyde, all CC showed a clear trend of reduction in the emissions from B2 to B100 (40% reduction, on average). Both individual and total CC emission factors (pg g -1 of fuel burnt) were calculated for all tested biodiesel-diesel blends. The lowest total CC emission factor (2271 pg g -1) was found when B50 was used; the individual emission factors determined (pg g -1) were: 539.7 (formaldehyde), 1411 (acetaldehyde), 30.83 (acrolein), and 310.7 (propionaldehyde).

Higher Order Bases in a 2D Hybrid BEM/FEM Formulation

NASA Technical Reports Server (NTRS)

Fink, Patrick W.; Wilton, Donald R.

2002-01-01

The advantages of using higher order, interpolatory basis functions are examined in the analysis of transverse electric (TE) plane wave scattering by homogeneous, dielectric cylinders. A boundary-element/finite-element (BEM/FEM) hybrid formulation is employed in which the interior dielectric region is modeled with the vector Helmholtz equation, and a radiation boundary condition is supplied by an Electric Field Integral Equation (EFIE). An efficient method of handling the singular self-term arising in the EFIE is presented. The iterative solution of the partially dense system of equations is obtained using the Quasi-Minimal Residual (QMR) algorithm with an Incomplete LU Threshold (ILUT) preconditioner. Numerical results are shown for the case of an incident wave impinging upon a square dielectric cylinder. The convergence of the solution is shown versus the number of unknowns as a function of the completeness order of the basis functions.

Numerical simulations of icing in turbomachinery

NASA Astrophysics Data System (ADS)

Das, Kaushik

Safety concerns over aircraft icing and the high experimental cost of testing have spurred global interest in numerical simulations of the ice accretion process. Extensive experimental and computational studies have been carried out to understand the icing on external surfaces. No parallel initiatives were reported for icing on engine components. However, the supercooled water droplets in moist atmosphere that are ingested into the engine can impinge on the component surfaces and freeze to form ice deposits. Ice accretion could block the engine passage causing reduced airflow. It raises safety and performance concerns such as mechanical damage from ice shedding as well as slow acceleration leading to compressor stall. The current research aims at developing a computational methodology for prediction of icing phenomena on turbofan compression system. Numerical simulation of ice accretion in aircraft engines is highly challenging because of the complex 3-D unsteady turbomachinery flow and the effects of rotation on droplet trajectories. The aim of the present research focuses on (i) Developing a computational methodology for ice accretion in rotating turbomachinery components; (ii) Investigate the effect of inter-phase heat exchange; (iii) Characterize droplet impingement pattern and ice accretion at different operating conditions. The simulations of droplet trajectories are based on a Eulerian-Lagrangian approach for the continuous and discrete phases. The governing equations are solved in the rotating blade frame of reference. The flow field is computed by solving the 3-D solution of the compressible Reynolds Averaged Navier Stokes (RANS) equations. One-way interaction models simulate the effects of aerodynamic forces and the energy exchange between the flow and the droplets. The methodology is implemented in the cool, TURBODROP and applied to the flow field and droplet trajectories in NASA Roto-67r and NASA-GE E3 booster rotor. The results highlight the variation of impingement location and temperature with droplet size. It also illustrates the effect of rotor speed on droplet temperature rise. The computed droplet impingement statistics and flow properties are used to calculate ice shapes. It was found that the mass of accreted ice and maximum thickness is highly sensitive to rotor speed and radial location.

Analysis of liquid-metal-jet impingement cooling in a corner region and for a row of jets

NASA Technical Reports Server (NTRS)

Siegel, R.

1975-01-01

A conformal mapping method was used to analyze liquid-metal-jet impingement heat transfer. The jet flow region and energy equation are transformed to correspond to uniform flow in a parallel plate channel with nonuniform heat addition along a portion of one wall. The exact solution for the wall-temperature distribution was obtained in the transformed channel, and the results are mapped back into the physical plane. Two geometries are analyzed. One is for a single slot jet directed either into an interior corner formed by two flat plates, or over the external sides of the corner; the flat plates are uniformly heated, and the corner can have various included angles. The heat-transfer coefficient at the stagnation point at the apex of the plates is obtained as a function of the corner angle, and temperature distributions are calculated along the heated walls. The second geometry is an infinite row of uniformly spaced parallel slot jets impinging normally against a uniformly heated plate. The heat-transfer behavior is obtained as a function of the spacing between the jets. Results are given for several jet Peclet numbers from 5 to 50.

IMPINGER SOLUTIONS FOR THE EFFICIENT CAPTURE OF GASEOUS MERCURY SPECIES USING DIRECT INJECTION NEBULIZATION INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY (DIN-ICP/MS) ANALYSIS

EPA Science Inventory

Currently there are no EPA reference sampling mehtods that have been promulgated for measuring Hg from coal combustion sources. EPA Method 29 is most commonly applied. The ASTM Ontario Hydro Draft Method for measuring oxidized, elemental, particulate-bound and total Hg is now und...

A zonal method for modeling powered-lift aircraft flow fields

NASA Technical Reports Server (NTRS)

Roberts, D. W.

1989-01-01

A zonal method for modeling powered-lift aircraft flow fields is based on the coupling of a three-dimensional Navier-Stokes code to a potential flow code. By minimizing the extent of the viscous Navier-Stokes zones the zonal method can be a cost effective flow analysis tool. The successful coupling of the zonal solutions provides the viscous/inviscid interations that are necessary to achieve convergent and unique overall solutions. The feasibility of coupling the two vastly different codes is demonstrated. The interzone boundaries were overlapped to facilitate the passing of boundary condition information between the codes. Routines were developed to extract the normal velocity boundary conditions for the potential flow zone from the viscous zone solution. Similarly, the velocity vector direction along with the total conditions were obtained from the potential flow solution to provide boundary conditions for the Navier-Stokes solution. Studies were conducted to determine the influence of the overlap of the interzone boundaries and the convergence of the zonal solutions on the convergence of the overall solution. The zonal method was applied to a jet impingement problem to model the suckdown effect that results from the entrainment of the inviscid zone flow by the viscous zone jet. The resultant potential flow solution created a lower pressure on the base of the vehicle which produces the suckdown load. The feasibility of the zonal method was demonstrated. By enhancing the Navier-Stokes code for powered-lift flow fields and optimizing the convergence of the coupled analysis a practical flow analysis tool will result.

The importance of bony impingement in restricting flexion after total knee arthroplasty: computer simulation model with clinical correlation.

PubMed

Mizu-Uchi, Hideki; Colwell, Clifford W; Fukagawa, Shingo; Matsuda, Shuichi; Iwamoto, Yukihide; D'Lima, Darryl D

2012-10-01

We constructed patient-specific models from computed tomography data after total knee arthroplasty to predict knee flexion based on implant-bone impingement. The maximum flexion before impingement between the femur and the tibial insert was computed using a musculoskeletal modeling program (KneeSIM; LifeModeler, Inc, San Clemente, California) during a weight-bearing deep knee bend. Postoperative flexion was measured in a clinical cohort of 21 knees (low-flex group: 6 knees with <100° of flexion and high-flex group: 15 size-matched knees with >125° of flexion at 2 years). Average predicted flexion angles were within 2° of clinical measurements for the high-flex group. In the low-flex group, 4 cases had impingement involving the bone cut at the posterior condyle, and the average predicted knee flexion was 102° compared with 93° measured clinically. These results indicate that the level of the distal femoral resection should be carefully planned and that exposed bone proximal to the tips of the posterior condyles of the femoral component should be removed if there is risk of impingement. Copyright © 2012 Elsevier Inc. All rights reserved.

MRI of lower extremity impingement and friction syndromes in children

PubMed Central

Aydıngöz, Üstün; Özdemir, Zeynep Maraş; Güneş, Altan; Ergen, Fatma Bilge

2016-01-01

Although generally more common in adults, lower extremity impingement and friction syndromes are also observed in the pediatric age group. Encompassing femoroacetabular impingement, iliopsoas impingement, subspine impingement, and ischiofemoral impingement around the hip; patellar tendon–lateral femoral condyle friction syndrome; iliotibial band friction syndrome; and medial synovial plica syndrome in the knee as well as talocalcaneal impingement on the hindfoot, these syndromes frequently cause pain and may mimic other, and occasionally more ominous, conditions in children. Magnetic resonance imaging (MRI) plays a key role in the diagnosis of musculoskeletal impingement and friction syndromes. Iliopsoas, subspine, and ischiofemoral impingements have been recently described, while some features of femoroacetabular and talocalcaneal impingements have recently gained increased relevance in the pediatric population. Fellowship-trained pediatric radiologists and radiologists with imaging workloads of exclusively or overwhelmingly pediatric patients (particularly those without a structured musculoskeletal imaging program as part of their imaging training) specifically need to be aware of these rare syndromes that mostly have quite characteristic imaging findings. This review highlights MRI features of lower extremity impingement and friction syndromes in children and provides updated pertinent pathophysiologic and clinical data. PMID:27538047

Steam exit flow design for aft cavities of an airfoil

DOEpatents

Storey, James Michael; Tesh, Stephen William

2002-01-01

Turbine stator vane segments have inner and outer walls with vanes extending therebetween. The inner and outer walls have impingement plates. Steam flowing into the outer wall passes through the impingement plate for impingement cooling of the outer wall surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. A skirt or flange structure is provided for shielding the steam cooling impingement holes adjacent the inner wall aerofoil fillet region of the nozzle from the steam flow exiting the aft nozzle cavities. Moreover, the gap between the flash rib boss and the cavity insert is controlled to minimize the flow of post impingement cooling media therebetween. This substantially confines outflow to that exiting via the return channels, thus furthermore minimizing flow in the vicinity of the aerofoil fillet region that may adversely affect impingement cooling thereof.

Numerical Study of Impingement Location of Liquid Jet Poured from a Tilting Ladle with Lip Spout

NASA Astrophysics Data System (ADS)

Castilla, R.; Gamez-Montero, P. J.; Raush, G.; Khamashta, M.; Codina, E.

2017-04-01

A new approach for simulating liquid poured from a tilting lip spout is presented, using neither a dynamic mesh nor the moving solid solution method. In this case only the tilting ladle is moving, so we propose to rotate the gravitational acceleration at an angular velocity prescribed by a geometrical and dynamical calculation to keep the poured flow rate constant. This angular velocity is applied to modify the orientation of the gravity vector in computational fluid dynamics (CFD) simulations using the OpenFOAM® toolbox. Also, fictitious forces are considered. The modified solver is used to calculate the impingement location for six spout geometries and compare the jet dispersion there. This method could offer an inexpensive tool to calculate optimal spout geometries to reduce sprue size in the metal casting industry.

Computed tomography assessment of hip joints in asymptomatic individuals in relation to femoroacetabular impingement.

PubMed

Kang, Alan C L; Gooding, Andrew J; Coates, Mark H; Goh, Tony D; Armour, Paul; Rietveld, John

2010-06-01

Femoroacetabular impingement has become a well-recognized entity predisposing to acetabular labral tears and chondral damage, and subsequently development of osteoarthritis of the hip joint. In the authors' experience, it is common to see bony abnormalities predisposing to femoroacetabular impingement in the contralateral asymptomatic hips in patients with unilateral femoroacetabular impingement. This study was undertaken to investigate the prevalence of bony abnormalities predisposing to femoroacetabular impingement in asymptomatic individuals without exposing study participants to unnecessary radiation. Cross-sectional study; Level of evidence, 4. Fifty individuals (100 hip joints), ranging from 15 to 40 years of age, who were seen at a local hospital between March and August 2008 with abdominal trauma or nonspecific abdominal pain in whom abdominal computed tomography was performed to aid diagnosis were prospectively studied. These patients were not known to have any history of hip-related problems. Raw data from the abdominal computed tomography scan, performed on a 64-slice multidetector computed tomography scanner, were reformatted using bone algorithm into several different planes. Several measurements and observations of the hip joints were made in relation to femoroacetabular impingement. The 100 hip joints from 50 patients with no history of hip problems demonstrated that 39% of the joints (31% of female, 48% of male joints) have at least 1 morphologic aspect predisposing to femoroacetabular impingement. The majority (66% to 100% ) of the findings were bilateral; 33% of female and 52% of male asymptomatic participants in our study had at least 1 predisposing factor for femoroacetabular impingement in 1 or both of their hip joints. Based on the data collected from this study, the acetabular crossover sign had a 71% sensitivity and 88% specificity for detecting acetabular retroversion. Nonquantitative assessment of the femoral head at the anterior, anterolateral, and lateral head/neck junctions demonstrated that 74% of the joints had an aspherical femoral head. The study demonstrated substantial prevalence of bony characteristics predisposing to femoroacetabular impingement in asymptomatic individuals according to the established measurement parameters in current literature.

Industrial stator vane with sequential impingement cooling inserts

DOEpatents

Jones, Russell B; Fedock, John A; Goebel, Gloria E; Krueger, Judson J; Rawlings, Christopher K; Memmen, Robert L

2013-08-06

A turbine stator vane for an industrial engine, the vane having two impingement cooling inserts that produce a series of impingement cooling from the pressure side to the suction side of the vane walls. Each insert includes a spar with a row of alternating impingement cooling channels and return air channels extending in a radial direction. Impingement cooling plates cover the two sides of the insert and having rows of impingement cooling holes aligned with the impingement cooling channels and return air openings aligned with the return air channel.

[Radiologic Presentation in Subspine Impingement and Correlation with Intraarticular Impingement in the Hip].

PubMed

Krüger, David R; Schütz, Michael; Perka, Carsten; Schröder, Jörg

2017-08-01

Background Besides the known intraarticular femoroacetabular impingement (FAI), recently forms of extra-articular impingement of the hip have been increasingly recognized. Recent studies have described an extra-articular impingement between a distal extension of the anterior inferior iliac spine (AIIS) and the femoral neck (AIIS or subspine impingement). Evidently, an association between this subspine impingement and an intraarticular FAI seems to exist. Little is known about the incidence of this impingement type and the value of its radiological diagnostics. The aim of this study was therefore to evaluate the correlation of a subspine impingement with intraarticular femoroacetabular impingement and radiological criteria of subspine impingement. Material and Methods In 2013 arthroscopic correction of intra-articular femoroacetabular impingement was performed in 80 cases. This collective was evaluated for simultaneous intraoperative findings of subspine impingement. In addition, the patients were evaluated for radiological signs of subspine impingement in conventional X-ray. A projection of the AIIS either below the acetabular sourcil or the anterior acetabular rim in an AP pelvis X-ray was considered as a radiological sign of low AIIS formation. These radiological findings were compared with the presence of intraoperative signs for subspine impingement, which are defined as a combination of focal capsule synovitis, labral ecchymosis close to the AIIS and a decreased offset between the acetabular rim and the AIIS. The specificity and sensitivity of the pre-operative radiological signs were calculated. Results A subspine impingement was found in 17 cases (21 %, 3 female, 14 male, mean age 28 years). A projection of the AIIS caudal to the acetabular sourcil in the AP pelvis X-ray was represented in 15 of the 17 cases detected (sensitivity 0.90, specificity 0.88). A projection below the anterior glenoid rim was detectable in 2 cases with symptomatic AIIS impingement (sensitivity 0.12, specificity 1). Conclusion A relevant proportion of patients with intraarticular FAI showed intraoperative signs for an additive extraarticular AIIS impingement. Preoperative pelvic X-rays are helpful with a sensitivity of 90 % in detecting the presence of a distal extension of the AIIS in FAI patients. Evaluation of the preoperative AP pelvis x-ray should include the projection of the AIIS. We recommend evaluation for subspine impingement during routine arthroscopy. Georg Thieme Verlag KG Stuttgart · New York.

Hip morphology predicts posterior hip impingement in a cadaveric model.

PubMed

Morris, William Z; Fowers, Cody A; Weinberg, Douglas S; Millis, Michael B; Tu, Leigh-Anne; Liu, Raymond W

2018-05-01

Posterior hip impingement is a recently-identified cause of hip pain. The purpose of this study is to characterise posterior femoroacetabular and ischiofemoral impingement and identify its predisposing morphologic traits. Two hundred and six cadaveric hips were randomly selected and taken through controlled motion in two pure axes associated with posterior hip impingement: external rotation (through the mechanical axis) and adduction (coronal plane). The range of motion and location of impingement was noted for each specimen. Morphologic traits including femoral/acetabular version, and true neck-shaft angle (TNSA) were also measured. External rotation impingement occurred between the femoral neck and acetabulum in 83.0% of hips, and between the lesser trochanter and ischial tuberosity in 17.0%. Adduction impingement occurred between the lesser trochanter and ischial tuberosity in 78.6% of hips, and between the femoral neck and acetabulum in 21.4%. Multiple regression revealed that increased femoral/acetabular version predicted earlier external rotation and adduction impingement. Unstandardised betas ranging from -0.39 to -0.64 reflect that each degree of increased femoral/acetabular version individually accounts for a loss of external rotation or adduction of approximately half a degree before impingement ( p < 0.001 for each). Increased TNSA was associated with earlier adduction impingement only (unstandardised beta -0.35, p = 0.005). Relative femoral/acetabular anteversion was associated with earlier posterior hip impingement. Coxa valga was associated with earlier adduction impingement, but protective against external rotation impingement. These findings highlight the importance of monitoring correction during femoral/acetabular osteotomies, as overcorrection of retroversion may predispose to earlier posterior impingement.

Copper nanoparticles impinging on a curved channel with compliant walls and peristalsis

NASA Astrophysics Data System (ADS)

Akbar, Noreen Sher; Maraj, E. N.; Butt, Adil Wahid

2014-08-01

In the present article peristaltic transport of copper nanofluids in a curved channel with compliant walls is analytically studied. The mathematical analysis is carried out under the low Reynolds number and long wavelenght approximation. The exact solutions are computed for fluid velocity and temperature profile. The effect of meaningful parameters are shown graphically in the last section.

Extra-articular hip impingement: a narrative review of the literature

PubMed Central

Cheatham, Scott W.

2016-01-01

There is growing subgroup of patients with poor outcomes after hip arthroscopy for intra-articular pathology suggesting unrecognized cause(s) of impingement may exist. Extra-articular hip impingement (EHI) is an emerging group of conditions that have been associated with intra-articular causes of impingement and may be an unrecognized source of pain. EHI is caused by abnormal contact between the extra-articular regions of the proximal femur and pelvis. This review discusses the most common forms for EHI including: central iliopsoas impingement, subspine impingement, ischiofemoral impingement, and greater trochanteric-pelvic impingement. The clinical presentation of each pathology will be discussed since EHI conditions share similar clinical features as the intra-articular pathology but also contain some unique characteristics. PMID:27069266

Internal Impingement of the Shoulder: A Risk of False Positive Test Outcomes in External Impingement Tests?

PubMed

Leschinger, Tim; Wallraff, Christopher; Müller, Dirk; Hackenbroch, Matthias; Bovenschulte, Henning; Siewe, Jan

2017-01-01

External impingement tests are considered as being particularly reliable for identifying subacromial and coracoid shoulder impingement mechanisms. The purpose of the present study was to evaluate if these tests are likely to provoke an internal shoulder impingement mechanism which, in cases of a pathologic condition, can lead to a positive test result. In 37 subjects, the mechanical contact between the glenoid rim and the rotator cuff (RC) was measured quantitatively and qualitatively in external impingement test positions using an open MRI system. Mechanical contact of the supraspinatus with the posterosuperior glenoid was present in 30 subjects in the Neer test. In the Hawkins test, the subscapularis was in contact with the anterosuperior glenoid in 33 subjects and the supraspinatus in 18. In the horizontal impingement test, anterosuperior contact of the supraspinatus with the glenoid was identified in 35 subjects. The Neer, Hawkins, and horizontal impingement tests are likely to provoke the mechanism of an internal shoulder impingement. A posterosuperior internal impingement mechanism is being provoked predominately in the Neer test. The Hawkins test narrows the distance between the insertions of the subscapularis and supraspinatus and the anterosuperior labrum, which leads to an anterosuperior impingement mechanism.

Fluid dynamics and convective heat transfer in impinging jets through implementation of a high resolution liquid crystal technique

NASA Technical Reports Server (NTRS)

Kim, K.; Wiedner, B.; Camci, C.

1993-01-01

A combined convective heat transfer and fluid dynamics investigation in a turbulent round jet impinging on a flat surface is presented. The experimental study uses a high resolution liquid crystal technique for the determination of the convective heat transfer coefficients on the impingement plate. The heat transfer experiments are performed using a transient heat transfer method. The mean flow and the character of turbulent flow in the free jet is presented through five hole probe and hot wire measurements, respectively. The flow field character of the region near the impingement plate plays an important role in the amount of convective heat transfer. Detailed surveys obtained from five hole probe and hot wire measurements are provided. An extensive validation of the liquid crystal based heat transfer method against a conventional technique is also presented. After a complete documentation of the mean and turbulent flow field, the convective heat transfer coefficient distributions on the impingement plate are presented. The near wall of the impingement plate and the free jet region is treated separately. The current heat transfer distributions are compared to other studies available from the literature. The present paper contains complete sets of information on the three dimensional mean flow, turbulent velocity fluctuations, and convective heat transfer to the plate. The experiments also prove that the present nonintrusive heat transfer method is highly effective in obtaining high resolution heat transfer maps with a heat transfer coefficient uncertainty of 5.7 percent.

Impingement around the hip: beyond cam and pincer

PubMed Central

Bech, Niels Hendrik; Haverkamp, Daniel

2018-01-01

In this review, we bring to the attention of the reader three relatively unknown types of hip impingement. We explain the concept of low anterior inferior iliac spine (AIIS) impingement, also known as sub-spine impingement, ischio-femoral impingement (IFI) and pelvi-trochanteric impingement. For each type of impingement, we performed a search of relevant literature. We searched the PubMed, Medline (Ovid) and Embase databases from 1960 to March 2016. For each different type of impingement, a different search strategy was conducted. In total, 19 studies were included and described. No data analysis was performed since there was not much comparable data between studies. An overview of symptoms, clinical tests and possible surgical treatment options for the three different types of extra-articular impingement is provided. Several disorders around the hip can cause similar complaints. Therefore, we plead for a standardized classification. In young and athletic patients, in particular, there is much to gain if hip impingement is diagnosed early. Cite this article: EFORT Open Rev 2018;3:30-38. DOI: 10.1302/2058-5241.3.160068 PMID:29657843

Aeroacoustic Characteristics of Supersonic Impinging Jets

NASA Astrophysics Data System (ADS)

Worden, Theodore James

High-speed impinging jets are often generated by the propulsive systems of aerospace launch vehicles and tactical aircraft. In many instances, the presence of these impinging jets creates a hazard for flight operations personnel due to the extremely high noise levels and unsteady loads produced by fluid-surface interaction. In order to effectively combat these issues, a fundamental understanding of the flow physics and dominant acoustic behavior is essential. There are inherent challenges in performing such investigations, especially with the need to simulate the flowfield under realistic operational conditions (temperature, Mach number, etc.) and in configurations that are relevant to full-scale application. A state-of-the-art high-temperature flow facility at Florida State University has provided a unique opportunity to experimentally investigate the high-speed impinging jet flowfield at application-relevant conditions. Accordingly, this manuscript reports the findings of several experimental studies on high-temperature supersonic impinging jets in multiple configurations. The overall objective of these studies is to characterize the complex relationship between the hydrodynamic and acoustic fields. A fundamental parametric investigation has been performed to document the flowfield and acoustic characteristics of an ideally-expanded supersonic air jet impinging onto a semi-infinite flat plate at ambient and heated jet conditions. The experimental program has been designed to span a widely-applicable geometric parameter space, and as such, an extensive database of the flow and acoustic fields has been developed for impingement distances in the range 1d to 12d, impingement angles in the range 45 degrees to 90 degrees, and jet stagnation temperatures from 289K to 811K (TTR = 1.0 to 2.8). Measurements include point-wise mean and unsteady pressure on the impingement surface, time-resolved shadowgraphy of the flowfield, and fully three-dimensional near field acoustics. Aside from detailed documentation of the flow and acoustic fields, this work aims to develop a physical understanding of the noise sources generated by impingement. Correlation techniques are employed to localize and quantify the spatial extent of broadband noise sources in the near-impingement region and to characterize their frequency content. Additionally, discrete impingement tones are documented for normal and oblique incidence angles, and an empirical model of the tone frequencies has been developed using velocity data extracted from time-resolved shadowgraphy together with a simple modification to the conventional feedback formula to account for non-normal incidence. Two application-based studies have also been undertaken. In simulating a vertical take-off and landing aircraft in hover, the first study of a normally-impinging jet outfitted with lift-plate characterizes the flow-acoustic interaction between the high-temperature jet and the underside of an aircraft and documents the effectiveness of an active flow control technique known as `steady microjet injection' to mitigate high noise levels and unsteady phenomena. The second study is a detailed investigation of the jet blast deflector/carrier deck configuration aimed at gaining a better understanding of the noise field generated by a jet operating on a flight deck. The acoustic directionality and spectral characteristics are documented for a model-scale carrier deck with particular focus on locations that are pertinent to flight operations personnel.

Dynamics of simultaneously impinging drops on a dry surface: Role of inhomogeneous wettability and impact shape.

PubMed

Ashoke Raman, K

2018-04-15

The quality of the printed lines in applications such as ink-jet printing and additive manufacturing is affected by the interactions between the impinging drops. Impact shape and the inhomogeneity in surface wettability govern the spreading and recoiling dynamics of the interacting drops. Hence, understanding the role of these factors on the interaction dynamics is essential to optimize these applications. Phase-field based lattice Boltzmann method solver has been employed to investigate the interaction dynamics of two simultaneously impinging drops onto a dry surface. A geometry-based contact angle scheme is used to model the moving contact line. Numerical simulations reveal that the previously identified interaction modes (Raman et al., 2017) are sensitive to the contact angle hysteresis, resulting in different impact outcomes. Two different interaction mechanisms have been discerned when drops impinge on a surface with a wettability gradient. It is shown that the deviation from the spherical geometry of the impact shape leads to different spreading behaviors and droplet morphology around the connecting region. With the increase in the cross-sectional aspect ratio, the interaction dynamics of oblate-oblate combination is similar to its spherical counterpart, albeit at a faster recoiling rate. Copyright © 2018 Elsevier Inc. All rights reserved.

Numerical investigation of mist/air impingement cooling on ribbed blade leading-edge surface.

PubMed

Bian, Qingfei; Wang, Jin; Chen, Yi-Tung; Wang, Qiuwang; Zeng, Min

2017-12-01

The working gas turbine blades are exposed to the environment of high temperature, especially in the leading-edge region. The mist/air two-phase impingement cooling has been adopted to enhance the heat transfer on blade surfaces and investigate the leading-edge cooling effectiveness. An Euler-Lagrange particle tracking method is used to simulate the two-phase impingement cooling on the blade leading-edge. The mesh dependency test has been carried out and the numerical method is validated based on the available experimental data of mist/air cooling with jet impingement on a concave surface. The cooling effectiveness on three target surfaces is investigated, including the smooth and the ribbed surface with convex/concave columnar ribs. The results show that the cooling effectiveness of the mist/air two-phase flow is better than that of the single-phase flow. When the ribbed surfaces are used, the heat transfer enhancement is significant, the surface cooling effectiveness becomes higher and the convex ribbed surface presents a better performance. With the enhancement of the surface heat transfer, the pressure drop in the impingement zone increases, but the incremental factor of the flow friction is smaller than that of the heat transfer enhancement. Copyright © 2017 Elsevier Ltd. All rights reserved.

Extrarticular hip impingement.

PubMed

Marin-Peña, Óliver; Sierra-Madrid, Pablo; Lax-Pérez, Raquel; Ferrero-Manzanal, Francisco

2016-05-14

Extrarticular causes of impingement have a current, interesting role in the complaint of groin pain in athletes. Subspine impingement is related to a prominent anterior inferior iliac spine (AIIS) and is actually described as a frequent cause of groin pain. Ischiofemoral impingement is described when the space between the lesser trochanter is decreased. Psoas impingement appears between the psoas tendon and the anterior labrum and anterior acetabular rim.

Phase-Field Modeling of Polycrystalline Solidification: From Needle Crystals to Spherulites—A Review

NASA Astrophysics Data System (ADS)

Gránásy, László; Rátkai, László; Szállás, Attila; Korbuly, Bálint; Tóth, Gyula I.; Környei, László; Pusztai, Tamás

2014-04-01

Advances in the orientation-field-based phase-field (PF) models made in the past are reviewed. The models applied incorporate homogeneous and heterogeneous nucleation of growth centers and several mechanisms to form new grains at the perimeter of growing crystals, a phenomenon termed growth front nucleation. Examples for PF modeling of such complex polycrystalline structures are shown as impinging symmetric dendrites, polycrystalline growth forms (ranging from disordered dendrites to spherulitic patterns), and various eutectic structures, including spiraling two-phase dendrites. Simulations exploring possible control of solidification patterns in thin films via external fields, confined geometry, particle additives, scratching/piercing the films, etc. are also displayed. Advantages, problems, and possible solutions associated with quantitative PF simulations are discussed briefly.

Development and tests of molybdenum armored copper components for MITICA ion source

NASA Astrophysics Data System (ADS)

Pavei, Mauro; Böswirth, Bernd; Greuner, Henri; Marcuzzi, Diego; Rizzolo, Andrea; Valente, Matteo

2016-02-01

In order to prevent detrimental material erosion of components impinged by back-streaming positive D or H ions in the megavolt ITER injector and concept advancement beam source, a solution based on explosion bonding technique has been identified for producing a 1 mm thick molybdenum armour layer on copper substrate, compatible with ITER requirements. Prototypes have been recently manufactured and tested in the high heat flux test facility Garching Large Divertor Sample Test Facility (GLADIS) to check the capability of the molybdenum-copper interface to withstand several thermal shock cycles at high power density. This paper presents both the numerical fluid-dynamic analyses of the prototypes simulating the test conditions in GLADIS as well as the experimental results.

Development and tests of molybdenum armored copper components for MITICA ion source

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

Pavei, Mauro, E-mail: mauro.pavei@igi.cnr.it; Marcuzzi, Diego; Rizzolo, Andrea

2016-02-15

In order to prevent detrimental material erosion of components impinged by back-streaming positive D or H ions in the megavolt ITER injector and concept advancement beam source, a solution based on explosion bonding technique has been identified for producing a 1 mm thick molybdenum armour layer on copper substrate, compatible with ITER requirements. Prototypes have been recently manufactured and tested in the high heat flux test facility Garching Large Divertor Sample Test Facility (GLADIS) to check the capability of the molybdenum-copper interface to withstand several thermal shock cycles at high power density. This paper presents both the numerical fluid-dynamic analysesmore » of the prototypes simulating the test conditions in GLADIS as well as the experimental results.« less

Development and tests of molybdenum armored copper components for MITICA ion source.

PubMed

Pavei, Mauro; Böswirth, Bernd; Greuner, Henri; Marcuzzi, Diego; Rizzolo, Andrea; Valente, Matteo

2016-02-01

In order to prevent detrimental material erosion of components impinged by back-streaming positive D or H ions in the megavolt ITER injector and concept advancement beam source, a solution based on explosion bonding technique has been identified for producing a 1 mm thick molybdenum armour layer on copper substrate, compatible with ITER requirements. Prototypes have been recently manufactured and tested in the high heat flux test facility Garching Large Divertor Sample Test Facility (GLADIS) to check the capability of the molybdenum-copper interface to withstand several thermal shock cycles at high power density. This paper presents both the numerical fluid-dynamic analyses of the prototypes simulating the test conditions in GLADIS as well as the experimental results.

Water droplet impingement on airfoils and aircraft engine inlets for icing analysis

NASA Technical Reports Server (NTRS)

Papadakis, Michael; Elangovan, R.; Freund, George A., Jr.; Breer, Marlin D.

1991-01-01

This paper includes the results of a significant research program for verification of computer trajectory codes used in aircraft icing analysis. Experimental water droplet impingement data have been obtained in the NASA Lewis Research Center Icing Research Tunnel for a wide range of aircraft geometries and test conditions. The body whose impingement characteristics are required is covered at strategic locations by thin strips of moisture absorbing (blotter) paper and then exposed to an airstream containing a dyed-water spray cloud. Water droplet impingement data are extracted from the dyed blotter strips by measuring the optical reflectance of the dye deposit on the strips with an automated reflectometer. Impingement characteristics for all test geometries have also been calculated using two recently developed trajectory computer codes. Good agreement is obtained with experimental data. The experimental and analytical data show that maximum impingement efficiency and impingement limits increase with mean volumetric diameter for all geometries tested. For all inlet geometries tested, as the inlet mass flow is reduced, the maximum impingement efficiency is reduced and the location of the maximum impingement shifts toward the inlet inner cowl.

Cooling circuit for steam and air-cooled turbine nozzle stage

DOEpatents

Itzel, Gary Michael; Yu, Yufeng

2002-01-01

The turbine vane segment includes inner and outer walls with a vane extending therebetween. The vane includes leading and trailing edge cavities and intermediate cavities. An impingement plate is spaced from the outer wall to impingement-cool the outer wall. Post-impingement cooling air flows through holes in the outer wall to form a thin air-cooling film along the outer wall. Cooling air is supplied an insert sleeve with openings in the leading edge cavity for impingement-cooling the leading edge. Holes through the leading edge afford thin-film cooling about the leading edge. Cooling air is provided the trailing edge cavity and passes through holes in the side walls of the vane for thin-film cooling of the trailing edge. Steam flows through a pair of intermediate cavities for impingement-cooling of the side walls. Post-impingement steam flows to the inner wall for impingement-cooling of the inner wall and returns the post-impingement cooling steam through inserts in other intermediate cavities for impingement-cooling the side walls of the vane.

Numerical Simulation of Rocket Exhaust Interaction with Lunar Soil

NASA Technical Reports Server (NTRS)

Liever, Peter; Tosh, Abhijit; Curtis, Jennifer

2012-01-01

This technology development originated from the need to assess the debris threat resulting from soil material erosion induced by landing spacecraft rocket plume impingement on extraterrestrial planetary surfaces. The impact of soil debris was observed to be highly detrimental during NASA s Apollo lunar missions and will pose a threat for any future landings on the Moon, Mars, and other exploration targets. The innovation developed under this program provides a simulation tool that combines modeling of the diverse disciplines of rocket plume impingement gas dynamics, granular soil material liberation, and soil debris particle kinetics into one unified simulation system. The Unified Flow Solver (UFS) developed by CFDRC enabled the efficient, seamless simulation of mixed continuum and rarefied rocket plume flow utilizing a novel direct numerical simulation technique of the Boltzmann gas dynamics equation. The characteristics of the soil granular material response and modeling of the erosion and liberation processes were enabled through novel first principle-based granular mechanics models developed by the University of Florida specifically for the highly irregularly shaped and cohesive lunar regolith material. These tools were integrated into a unique simulation system that accounts for all relevant physics aspects: (1) Modeling of spacecraft rocket plume impingement flow under lunar vacuum environment resulting in a mixed continuum and rarefied flow; (2) Modeling of lunar soil characteristics to capture soil-specific effects of particle size and shape composition, soil layer cohesion and granular flow physics; and (3) Accurate tracking of soil-borne debris particles beginning with aerodynamically driven motion inside the plume to purely ballistic motion in lunar far field conditions. In the earlier project phase of this innovation, the capabilities of the UFS for mixed continuum and rarefied flow situations were validated and demonstrated for lunar lander rocket plume flow impingement under lunar vacuum conditions. Applications and improvements to the granular flow simulation tools contributed by the University of Florida were tested against Earth environment experimental results. Requirements for developing, validating, and demonstrating this solution environment were clearly identified, and an effective second phase execution plan was devised. In this phase, the physics models were refined and fully integrated into a production-oriented simulation tool set. Three-dimensional simulations of Apollo Lunar Excursion Module (LEM) and Altair landers (including full-scale lander geometry) established the practical applicability of the UFS simulation approach and its advanced performance level for large-scale realistic problems.

Sequential cooling insert for turbine stator vane

DOEpatents

Jones, Russell B.; Krueger, Judson J.; Plank, William L.

2014-04-01

A sequential impingement cooling insert for a turbine stator vane that forms a double impingement for the pressure and suction sides of the vane or a triple impingement. The insert is formed from a sheet metal formed in a zigzag shape that forms a series of alternating impingement cooling channels with return air channels, where pressure side and suction side impingement cooling plates are secured over the zigzag shaped main piece. Another embodiment includes the insert formed from one or two blocks of material in which the impingement channels and return air channels are machined into each block.

Sequential cooling insert for turbine stator vane

DOEpatents

Jones, Russel B; Krueger, Judson J; Plank, William L

2014-11-04

A sequential impingement cooling insert for a turbine stator vane that forms a double impingement for the pressure and suction sides of the vane or a triple impingement. The insert is formed from a sheet metal formed in a zigzag shape that forms a series of alternating impingement cooling channels with return air channels, where pressure side and suction side impingement cooling plates are secured over the zigzag shaped main piece. Another embodiment includes the insert formed from one or two blocks of material in which the impingement channels and return air channels are machined into each block.

Determination of wind tunnel constraint effects by a unified pressure signature method. Part 2: Application to jet-in-crossflow

NASA Technical Reports Server (NTRS)

Hackett, J. E.; Sampath, S.; Phillips, C. G.

1981-01-01

The development of an improved jet-in-crossflow model for estimating wind tunnel blockage and angle-of-attack interference is described. Experiments showed that the simpler existing models fall seriously short of representing far-field flows properly. A new, vortex-source-doublet (VSD) model was therefore developed which employs curved trajectories and experimentally-based singularity strengths. The new model is consistent with existing and new experimental data and it predicts tunnel wall (i.e. far-field) pressures properly. It is implemented as a preprocessor to the wall-pressure-signature-based tunnel interference predictor. The supporting experiments and theoretical studies revealed some new results. Comparative flow field measurements with 1-inch "free-air" and 3-inch impinging jets showed that vortex penetration into the flow, in diameters, was almost unaltered until 'hard' impingement occurred. In modeling impinging cases, a 'plume redirection' term was introduced which is apparently absent in previous models. The effects of this term were found to be very significant.

Results of a space shuttle pulme impingement investigation at stage separation in the NASA-MSFC impulse base flow facility

NASA Technical Reports Server (NTRS)

Mccanna, R. W.; Sims, W. H.

1972-01-01

Results are presented for an experimental space shuttle stage separation plume impingement program conducted in the NASA-Marshall Space Flight Center's impulse base flow facility (IBFF). Major objectives of the investigation were to: (1)determine the degree of dual engine exhaust plume simulation obtained using the equivalent engine; (2) determine the applicability of the analytical techniques; and (3) obtain data applicable for use in full-scale studies. The IBFF tests determined the orbiter rocket motor plume impingement loads, both pressure and heating, on a 3 percent General Dynamics B-15B booster configuration in a quiescent environment simulating a nominal staging altitude of 73.2 km (240,00 ft). The data included plume surveys of two 3 percent scale orbiter nozzles, and a 4.242 percent scaled equivalent nozzle - equivalent in the sense that it was designed to have the same nozzle-throat-to-area ratio as the two 3 percent nozzles and, within the tolerances assigned for machining the hardware, this was accomplished.

Numerical analysis of conjugate heat transfer due to oblique impingement of turbulent slot jet onto a flat plate

NASA Astrophysics Data System (ADS)

Shashikant, Patel, Devendra Kumar; Kumar, Jayesh; Kumar, Vishwajeet

2018-04-01

The conjugate heat transfer due to oblique impingement of two-dimensional, steady state, incompressible, turbulent slot jet on a uniformly heated flat plate has been studied in the present work. The standard high Reynolds number two-equation k - ɛ eddy viscosity model has been used for numerical simulation. The Reynolds number based on the hydraulic diameter of nozzle exit and turbulent intensity maintained at 9, 900 and 2% respectively. The angle of inclination 30°, 45°, 60° and, 75° degrees are considered for the numerical study. A uniform temperature higher than the jet exit temperature is provided to the bottom surface of the plate. The flow field have been studied using the contour plots of pressure and velocity in the fluid domain. The influence of inclination on the distribution of the local Nusselt number over the surface of impingement have been presented. It is found that the angle of impingement influences the flow field and heat transfer characteristics more in the downhill direction of the stagnation zone compared to the uphill direction.

Experimental and numerical investigations of the impingement of an oblique liquid jet onto a superhydrophobic surface: energy transformation

NASA Astrophysics Data System (ADS)

Kibar, Ali

2016-02-01

This study presents the theory of impinging an oblique liquid jet onto a vertical superhydrophobic surface based on both experimental and numerical results. A Brassica oleracea leaf with a 160° apparent contact angle was used for the superhydrophobic surface. Distilled water was sent onto the vertical superhydrophobic surface in the range of 1750-3050 Reynolds number, with an inclination angle of 20°-40°, using a circular glass tube with a 1.75 mm inner diameter. The impinging liquid jet spread onto the surface governed by the inertia of the liquid and then reflected off the superhydrophobic surface due to the surface energy of the spreading liquid. Two different energy approaches, which have time-scale and per-unit length, were performed to determine transformation of the energy. The kinetic energy of the impinging liquid jet was transformed into the surface energy with an increasing interfacial surface area between the liquid and air during spreading. Afterwards, this surface energy of the spreading liquid was transformed into the reflection kinetic energy.

Film cooling air pocket in a closed loop cooled airfoil

DOEpatents

Yu, Yufeng Phillip; Itzel, Gary Michael; Osgood, Sarah Jane; Bagepalli, Radhakrishna; Webbon, Waylon Willard; Burdgick, Steven Sebastian

2002-01-01

Turbine stator vane segments have radially inner and outer walls with vanes extending between them. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. To provide for air film cooing of select portions of the airfoil outer surface, at least one air pocket is defined on a wall of at least one of the cavities. Each air pocket is substantially closed with respect to the cooling medium in the cavity and cooling air pumped to the air pocket flows through outlet apertures in the wall of the airfoil to cool the same.

The Accuracy of the Physical Examination for the Diagnosis of Midlumbar and Low Lumbar Nerve Root Impingement

PubMed Central

Suri, Pradeep; Rainville, James; Katz, Jeffrey N.; Jouve, Cristin; Hartigan, Carol; Limke, Janet; Pena, Enrique; Li, Ling; Swaim, Bryan; Hunter, David J

2010-01-01

Study Design Cross-sectional study with prospective recruitment. Objective To determine the accuracy of the physical examination for the diagnosis of midlumbar nerve root impingement (L2, L3, or L4), low lumbar nerve root impingement (L5 or S1) and level-specific lumbar nerve root impingement on magnetic resonance imaging (MRI), using individual tests and combinations of tests. Summary of Background Data The sensitivity and specificity of the physical examination for the localization of nerve root impingement has not been previously studied. Methods Sensitivities, specificities and LRs were calculated for the ability of individual tests and test combinations to predict the presence or absence of nerve root impingement at midlumbar, low lumbar, and specific nerve root levels. Results LRs ≥5.0 indicate moderate to large changes from pre-test probability of nerve root impingement to post-test probability. For the diagnosis of midlumbar impingement, the femoral stretch test (FST), crossed femoral stretch test (CFST), medial ankle pinprick sensation, and patellar reflex testing demonstrated LRs ≥5.0 (LR ∞). LRs ≥5.0 were seen with the combinations of FST and either patellar reflex testing (LR 7.0; 95% CI 2.3–21), or the sit-to-stand test (LR ∞). For the diagnosis of low lumbar impingement, the Achilles reflex test demonstrated a LR ≥5.0 (LR 7.1; CI 0.96–53); test combinations did not increase LRs. For the diagnosis of level-specific impingement, LRs ≥5.0 were seen for anterior thigh sensation at L2 (LR 13; 95% CI 1.8–87); FST at L3 (LR 5.7 ; 95% CI 2.3–4.4); patellar reflex testing (LR 7.7; 95% CI 1.7–35), medial ankle sensation (LR ∞), or CFST (LR 13; 95% CI 1.8–87) at L4; and hip abductor strength at L5(LR 11; 95% CI 1.3–84). Test combinations increased LRs for level-specific root impingement at the L4 level only. Conclusions Individual physical examination tests may provide clinical information which substantially alters the likelihood that midlumbar impingement, low lumbar impingement, or level-specific impingement is present. Test combinations improve diagnostic accuracy for midlumbar impingement. PMID:20543768

Infra-red signature neutron detector

DOEpatents

Bell, Zane William [Oak Ridge, TN; Boatner, Lynn Allen [Oak Ridge, TN

2009-10-13

A method of detecting an activator, the method including impinging with an activator a receptor material that includes a photoluminescent material that generates infrared radiation and generation a by-product of a nuclear reaction due to the activator impinging the receptor material. The method further includes generating light from the by-product via the Cherenkov effect, wherein the light activates the photoluminescent material so as to generate the infrared radiation. Identifying a characteristic of the activator based on the infrared radiation.

Chemical micro-sensor

DOEpatents

Ruggiero, Anthony J.

2005-05-03

An integrated optical capillary electrophoresis system for analyzing an analyte. A modulated optical pump beam impinges on an capillary containing the analyte/buffer solution which is separated by electrophoresis. The thermally-induced change in the index of refraction of light in said electrophoresis capillary is monitored using an integrated micro-interferometer. The interferometer includes a first interferometer arm intersecting the electrophoresis capillary proximate the excitation beam and a second, reference interferometer arm. Changes in index of refraction in the analyte measured by interrogating the interferometer state using white light interferometry and a phase-generated carrier demodulation technique. Background thermo-optical activity in the buffer solution is cancelled by splitting the pump beam and exciting pure buffer solution in a second section of capillary where it crosses the reference arm of the interferometer.

EFFECT OF IMPACTION, BOUNCE AND REAEROSOLIZATION ON THE COLLECTION EFFICIENCY OF IMPINGERS

EPA Science Inventory

The collection efficiency of liquid impingers was studied experimentally as a function of the sampling flow rate with test particles in the bacterial size range. Three impingers were tested: two All-Glass Impingers(AGI-4 and AGI-30),widely used for bioaerosol sampling, and a newl...

A six degree of freedom, plume-fuel optimal trajectory planner for spacecraft proximity operations using an A* node search. M.S. Thesis - MIT

NASA Technical Reports Server (NTRS)

Jackson, Mark Charles

1994-01-01

Spacecraft proximity operations are complicated by the fact that exhaust plume impingement from the reaction control jets of space vehicles can cause structural damage, contamination of sensitive arrays and instruments, or attitude misalignment during docking. The occurrence and effect of jet plume impingement can be reduced by planning approach trajectories with plume effects considered. An A* node search is used to find plume-fuel optimal trajectories through a discretized six dimensional attitude-translation space. A plume cost function which approximates jet plume isopressure envelopes is presented. The function is then applied to find relative costs for predictable 'trajectory altering' firings and unpredictable 'deadbanding' firings. Trajectory altering firings are calculated by running the spacecraft jet selection algorithm and summing the cost contribution from each jet fired. A 'deadbanding effects' function is defined and integrated to determine the potential for deadbanding impingement along candidate trajectories. Plume costs are weighed against fuel costs in finding the optimal solution. A* convergence speed is improved by solving approach trajectory problems in reverse time. Results are obtained on a high fidelity space shuttle/space station simulation. Trajectory following is accomplished by a six degree of freedom autopilot. Trajectories planned with, and without, plume costs are compared in terms of force applied to the target structure.

Field Studies Measuring the aerosolization of Endotoxin ...

EPA Pesticide Factsheets

Endotoxin is a component of the cell walls of Gram-negative bacteria and is known to be present in biosolids. Endotoxins have been shown to be a potent stimulator of the innate immune response causing airway irritation and shortness of breath. Class B biosolids are routinely applied to agricultural lands in the US to enhance soil properties and can be used as an alternative to chemical fertilizers. This study investigated the aerosolized endotoxin produced during the land application of Class B biosolids from various wastewater treatment plants on agricultural land and a concrete surface at two sites in Colorado, USA. Aerosolized endotoxin was captured using HiVol sampler fitted with glass fiber filter, polycarbonate filter cassette (both open and closed), and BioSampler impinger air samplers. Endotoxins were also measured in the bulk biosolids to allow for correlating bulk biosolids concentrations with aerosol emission rates. Endotoxin concentrations in biosolids, impinger solutions, and filter extracts were determined using the kinetic Limulus amebocyte lysate assay. Aerosolized endotoxin concentration was detected from all sites with levels ranging from 0.5 to 642 EU/m3. The four types of sampling apparatus were compared and the HiVol and open-faced cassette samplers used produced higher TWA measurements (EU/m3) than the impinger and closed cassette samplers. Ambient wind speed at the sites was found to be the variable best describing the results wit

Inhalation Exposure Method for Illegal Drugs.

PubMed

Inomata, Akiko; Ogata, Akio; Tada, Yukie; Nagasawa, Akemichi; Yuzawa, Katsuhiro; Ando, Hiroshi; Kubo, Yoshikazu; Takahashi, Hiroshi; Kaihoko, Fujifumi; Tanaka, Kazuyoshi; Nakajima, Jun'ichi; Suzuki, Atsuko; Uemura, Nozomi; Moriyasu, Takako; Watanabe, Daisuke; Ishihara, Kei; Usami, Takashi; Kamei, Satoru; Kohno, Yasuaki

2017-01-01

We developed a new inhalation exposure method to evaluate effects of synthetic cannabimimetics that are being distributed as new, unregulated drugs in the Tokyo area. We selected the commercial product "SOUTOU" containing AB-CHMINACA and 5F-AMB as the test drug and dried marshmallow (Althaea officinalis) leaves as the negative control. A half cigarette packed with dried marshmallow leaves or SOUTOU was ignited, then mainstream smoke from each was delivered to five mice in an exposure box. After the cigarettes were fully consumed, neurobehavioral observations and a catalepsy test were performed at 15, 30 and 60 min after exposure. The effluent air from the exposure box was poured into impingers containing acetonitrile (first impinger) and dimethyl sulfoxide (second impinger). The resulting solutions were analyzed to assess decomposition of the synthetic cannabimimetics. Mice exposed to SOUTOU smoke showed many excitement behaviors and some suppressive behaviors at 15, 30 and 60 min. These clearly included cannabimimetic specific pharmacological actions. Negative control mice also showed some suppressive behaviors at 15 min but these were attenuated at later times, nearly disappearing at 60 min. In addition, the behavioral effects observed in controls were less pronounced than those in SOUTOU exposed mice. The inhalation exposure method developed in our study would be effective for determining cannabinoid specific pharmacological effects of illegal drugs, as well as for assessing the presence of active compound(s) by comparing the test substance with a negative control.

Film cooling for a closed loop cooled airfoil

DOEpatents

Burdgick, Steven Sebastian; Yu, Yufeng Phillip; Itzel, Gary Michael

2003-01-01

Turbine stator vane segments have radially inner and outer walls with vanes extending therebetween. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. At least one film cooling hole is defined through a wall of at least one of the cavities for flow communication between an interior of the cavity and an exterior of the vane. The film cooling hole(s) are defined adjacent a potential low LCF life region, so that cooling medium that bleeds out through the film cooling hole(s) reduces a thermal gradient in a vicinity thereof, thereby the increase the LCF life of that region.

Magnetically operated beam dump for dumping high power beams in a neutral beamline

DOEpatents

Dagenhart, W.K.

1984-01-27

It is an object of this invention to provide a beam dump system for a neutral beam generator which lowers the time-averaged power density of the beam dump impingement surface. Another object of this invention is to provide a beam dump system for a neutral particle beam based on reionization and subsequent magnetic beam position modulation of the beam onto a beam dump surface to lower the time-averaged power density of the beam dump ion impingement surface.

On Heat Transfer - Stress Analysis of Modified Brick (Reed Filler) Upon Its Production Stage

NASA Astrophysics Data System (ADS)

Ornam, Kurniati; Kimsan, Masykur; Teguh Prakasa, Cadas; Ode Ngkoimani, La; Santi

2017-05-01

This paper aimed to scrutinize how burning process in modified brick’s production impinge on crack as a result of stress differentiation between two consecutive layers of the brick’s element. Diffusion engages in burning process of bricks, hence it generates thermal stress on element for different temperature between layers. This research focused on burning process in traditional production ward. Analytical of nonlinear equation and numerical solution, finite difference, were involved to obtain temperature value in each layer, followed by stress calculation. Based on the results, it can be concluded that crack occurs particularly on boundary area, since difussion tends to yield relatively more different value on it. Therefore, certain strategies, that may decrease this differentiation, are required to minimize number of cracks during brick’s production.

Jet slurry erosion performance of composite clad and its characterization

NASA Astrophysics Data System (ADS)

B, Lohit R.; Horakeri, Gururaj S.; Bhovi, Prabakhar M.

2016-09-01

In the present work, development of composite cladding consists of Cr23C6 (chromium carbide) as reinforcement particles 20 wt. % in Ni-based matrix 80 wt. % on austenitic stainless steel through exposure of microwave radiation has been carried out. The jet slurry erosion test was performed on microwave composite clad. The functional performance of composite clad has been evaluated for different parametric conditions like varying impingement velocity and impact angle. The increasing weight loss trend was observed with time for the first 30 min. after that the individual trend decreased; at high impingement velocity and maximum impact angle. SEM micrographs of eroded clad samples at various impact angle and impingement velocity were discussed. The maximum weight loss occurred at 90° angle and velocity of 60 m/s, and minimum at 30° angle and velocity of 20 m/s.

Design of a hip prosthetic tribometer based on salat gait cycle

NASA Astrophysics Data System (ADS)

Towijaya, T.; Ismail, R.; Jamari, J.

2017-01-01

Indonesia is the country with the largest muslim population in the world, most of the inhabitants do salat every day. THR (Total Hip Replacement) patients are prohibited from doing salat in normal gait. It leads to the damage of the hip joint prostheses due to impingement and dislocation.This paper reports the design of a pin-on-ring tribometer which is used to measure and analyze the wear volume and the impingement of hip joint prostheses during salat. The modifications of the femoral head and acetabular cup holder are performed to design the reciprocating motion for the movement of the hip prostheses. The interesting finding of the present research is a new mechanism of linked-bar which leads to the feasibility of the measurement of the wear volume and the impingement for THR patients during salat.

Changing Healthcare Industry Practices to Increase Opportunities for Covering the Uninsured and Underinsured

DTIC Science & Technology

2009-04-17

un/underinsured at this particular point of service often cited as an influential driver of increases in insurance premiums and a reason to cover...one cost driver may impinge on the resources supplied to another. Although the patient should be the focus, the practice of medicine subsumes...on a solution. Any motion to ameliorate duplicative cost drivers is expected to be challenged considering agency employees have a vested interest in

Influence of elliptical structure on impinging-jet-array heat transfer performances

NASA Astrophysics Data System (ADS)

Arjocu, Simona C.; Liburdy, James A.

1997-11-01

A three-by-three square array of submerged, elliptic, impinging jets in water was used to study the heat transfer distribution in the cooling process of a constant heat flux surface. Tow jet aspect ratios were used, 2 and 3, both with the same hydraulic diameter. The array was tested at Reynolds numbers from 300 to 1500 and impinging distances of 1 to 5 hydraulic diameters. Thermochromic liquid crystals wee used to map the local heat transfer coefficient using a transient method, while the jet temperature was kept constant. The liquid crystal images were recorded through an optical fiber coupled with a CCD camera and a frame grabber and analyzed based on an RGB-temperature calibration technique. The results are reported relative to the unit cell that is used to delimitate the central jet. The heat transfer variation is shown to depend on the impingement distance and Reynolds number. The elliptic jets exhibit axis switching, jet column instability and jet swaying. All of these mechanisms affect the enhancement of the heat transfer rate and its distribution. The results are compared in terms of average and local heat transfer coefficients, for both major and minor planes for the two jet aspect ratios.

[Secondary impingement syndrome in athletes].

PubMed

Jerosch, J; Castro, W H; Sons, H U

1990-12-01

Dysfunction of the shoulder joint is based not only on anatomic conditions. The consideration of the special kinesiology of the shoulder helps to understand the shoulder pathology. This mainly applies to young "overhead athletes" like swimmers, handball-, basketball-, volleyball-, and racketplayers. These disciplines cause stress on the anterior joint structures (capsule, ligaments, labrum, subscapularis tendon) and lead to anterior instability. This includes anterior subluxation or even dislocation. Finally, an impingement syndrome with the typical symptoms can frequently result from these conditions. The impingement-syndrome of the elderly must be considered as a primary disease, whereas the young overhead athlete suffers from the impingement syndrome as a secondary disease and does not take the first place in therapy. The first step in therapy should to be treat the muscular imbalance of the shoulder. To gain a regular pattern of motion the rotator cuff must be strengthened. This regimen is likely to be successful in 80-90% of the cases. If the conservative therapy fails the surgical treatment may come into consideration. Arthroscopic surgery has the advantage not to affect the proprioceptivity. To retain the previous level of performance an adequate rehabilitation programme is essential for the athlete.

Fluorescence Imaging Study of Impinging Underexpanded Jets

NASA Technical Reports Server (NTRS)

Inman, Jennifer A.; Danehy, Paul M.; Nowak, Robert J.; Alderfer, David W.

2008-01-01

An experiment was designed to create a simplified simulation of the flow through a hole in the surface of a hypersonic aerospace vehicle and the subsequent impingement of the flow on internal structures. In addition to planar laser-induced fluorescence (PLIF) flow visualization, pressure measurements were recorded on the surface of an impingement target. The PLIF images themselves provide quantitative spatial information about structure of the impinging jets. The images also help in the interpretation of impingement surface pressure profiles by highlighting the flow structures corresponding to distinctive features of these pressure profiles. The shape of the pressure distribution along the impingement surface was found to be double-peaked in cases with a sufficiently high jet-exit-to-ambient pressure ratio so as to have a Mach disk, as well as in cases where a flow feature called a recirculation bubble formed at the impingement surface. The formation of a recirculation bubble was in turn found to depend very sensitively upon the jet-exit-to-ambient pressure ratio. The pressure measured at the surface was typically less than half the nozzle plenum pressure at low jet pressure ratios and decreased with increasing jet pressure ratios. Angled impingement cases showed that impingement at a 60deg angle resulted in up to a factor of three increase in maximum pressure at the plate compared to normal incidence.

The 1991 version of the plume impingement computer program. Volume 1: Description

NASA Technical Reports Server (NTRS)

Bender, Robert L.; Somers, Richard E.; Prendergast, Maurice J.; Clayton, Joseph P.; Smith, Sheldon D.

1991-01-01

The objective of this contract was to continue development of a vacuum plume impingement evaluator to provide an analyst with a capability for rapid assessment of thruster plume impingement scenarios. The research was divided into three areas: Plume Impingement Computer Program (PLIMP) modification/validation; graphics development; and documentation in the form of a Plume Handbook and PLIMP Input Guide.

Outcome for Arthroscopic Treatment of Anterior Inferior Iliac Spine/Subspine Related Hip Impingement

PubMed Central

Nwachukwu, Benedict Uchenna; Chang, Brenda; Schairer, William W.; Fields, Kara G.; Nawabi, Danyal H.; Kelly, Bryan T.; Ranawat, Anil S.

2017-01-01

Objectives: Extra-articular disorders of the hip are under-recognized and under-reported. Extra-articular forms of hip impingement can include anterior inferior iliac spine (AIIS) related subspine impingement. The purpose of this study was to investigate the outcome after arthroscopic treatment of anterior inferior iliac spine (AIIS)/Subspine related hip impingement. Methods: A prospective institutional hip preservation registry was reviewed to identify patients that underwent isolated arthroscopic AIIS decompression. Primary outcome tools captured in the registry included: the modified Harris Hip Score (mHHS), the Hip Outcome Score (HOS) and the international Hip Outcome Tool (iHOT-33). Patients with minimum one-year follow-up were included. Meaningful outcome improvement was determined based on minimal clinically important difference (MCID). Statistical analyses were primarily descriptive. Results: Thirty-three patients with mean follow-up 19.1 months (range: 12-44 months) were identified. All patients were female with a mean age of 26.1 (+ 10.3) years. All patients were found to have an associated labral tear and the mean acetabular version was increased at 2 and 3 o’clock (14.5 and 19.8 respectively). Mean pre-operative outcome scores on the mHHS, HOS activities of daily living (ADL), HOS Sport and iHOT-33 were 57.2 (SD+15.3), 66.9 (SD+18.8), 43.9 (SD+23.6) and 33.5 (SD+18.3) respectively. At final available follow-up, mean scores on these outcome measures were 79.5 (SD+19.0), 86.8 (SD+15.8), 70.4 (SD+32.8) and 65.0 (SD+31.0) respectively. By the one-year follow-up interval MCID had been achieved in the majority of patients across all four tools. Conclusion: There is a paucity of outcome evidence on AIIS/Subspine related hip impingement. This study demonstrates that isolated subspine impingement can be a cause of hip disability even in the absence of FAI. Patients with isolated subspine impingement are more likely to be women and they present with low patient reported outcome scores. Meaningful outcome improvement can be achieved however with arthroscopic AIIS decompression.

Modeling Single-Phase and Boiling Liquid Jet Impingement Cooling in Power Electronics

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

Narumanchi, S. V. J.; Hassani, V.; Bharathan, D.

2005-12-01

Jet impingement has been an attractive cooling option in a number of industries over the past few decades. Over the past 15 years, jet impingement has been explored as a cooling option in microelectronics. Recently, interest has been expressed by the automotive industry in exploring jet impingement for cooling power electronics components. This technical report explores, from a modeling perspective, both single-phase and boiling jet impingement cooling in power electronics, primarily from a heat transfer viewpoint. The discussion is from the viewpoint of the cooling of IGBTs (insulated-gate bipolar transistors), which are found in hybrid automobile inverters.

Impingement of Water Droplets on NACA 65A004 Airfoil at 8 deg Angle of Attack

NASA Technical Reports Server (NTRS)

Brun, R. J.; Gallagher, H. M.; Vogt, D. E.

1954-01-01

The trajectories of droplets in the air flowing past an NACA 65AO04 airfoil at an angle of attack of 8 deg were determined.. The amount of water in droplet form impinging on the airfoil, the area of droplet impingement, and the rate of droplet impingement per unit area on the airfoil surface were calculated from the trajectories and presented to cover a large range of flight and atmospheric conditions. These impingement characteristics are compared briefly with those previously reported for the same airfoil at an angle of attack of 4 deg.

Liquid film target impingement scrubber

DOEpatents

McDowell, William J.; Coleman, Charles F.

1977-03-15

An improved liquid film impingement scrubber is provided wherein particulates suspended in a gas are removed by jetting the particle-containing gas onto a relatively small thin liquid layer impingement target surface. The impingement target is in the form of a porous material which allows a suitable contacting liquid from a pressurized chamber to exude therethrough to form a thin liquid film target surface. The gas-supported particles collected by impingement of the gas on the target are continuously removed and flushed from the system by the liquid flow through each of a number of pores in the target.

Surface pressure fluctuations due to an impinging underexpanded supersonic jet

NASA Astrophysics Data System (ADS)

Pundir, Binu

The impingement of supersonic jets on surfaces is of interest because of its important application to jet blast deflectors (JBD), and short takeoff and vertical landing aircraft (STOVL) during hover. Typically, on an aircraft carrier deck, the impingement of the jet blast on the deflector generates impingement tones, and structural vibrations, not only on the JBD but also on the ship deck. Therefore, apart from direct transmission of jet noise to the gallery level, there is a component of noise transmitted due to the impingement of the jet on the JBD. The objectives of this work are to study the pressure spectra (i) on a flat plate, and separately on a cone due to axisymmetric impingement of a supersonic underexpanded cold jet issuing from a convergent-divergent nozzle and (ii) on a plane jet impinging on a finite plate and an adjoining ground plane due to the impingement of a planar jet on the plate. The characteristics of the surface pressure fluctuations are numerically investigated using WIND-US 2.0. The time-dependent, compressible Euler equations for perfect gas are employed for the present computations. The impingement distance between the jet nozzle and the deflector plate, and the plate inclination with respect to the incident jet are varied. The impingement zone stagnation bubble and a high-speed radial jet with several embedded structures (shocklets) were identified on the perpendicular plate. Flows involving cones reveal the presence of detached cone shocks, enclosing a recirculation zone. The location and magnitude of the peak pressure on the cone surface are a strong function of the cone apex angle. For the two-dimensional jet impingement on angled plate the peak value of pressure occurs at normal jet impingement. The pressure at the intersection point of the plate and the ground plane is sometimes higher than the peak pressure on the plate. Beyond this point there is a sharp decrease in pressure. As the flow accelerates, an oblique shock is sometimes formed in this grazing flow region. A recirculation region at the lower lip of the nozzle was observed for all the separation distances and plate inclinations.

An experimental investigation of the impingement of a planar shock wave on an axisymmetric body at Mach 3

NASA Technical Reports Server (NTRS)

Brosh, A.; Kussoy, M. I.

1983-01-01

An experimental study of the flow caused by a planar shock wave impinging obliquely on a cylinder is presented. The complex three dimensional shock wave and boundary layer interaction occurring in practical problems, such as the shock wave impingement from the shuttle nose on an external fuel tank, and store carriage interference on a supersonic tactical aircraft were investigated. A data base for numerical computations of complex flows was also investigated. The experimental techniques included pressure measurements and oil flow patterns on the surface of the cylinder, and shadowgraphs and total and static pressure surveys on the leeward and windward planes of symmetry. The complete data is presented in tabular form. The results reveal a highly complex flow field with two separation zones, regions of high crossflow, and multiple reflected shocks and expansion fans.

Hip kinematics and kinetics in persons with and without cam femoroacetabular impingement during a deep squat task.

PubMed

Bagwell, Jennifer J; Snibbe, Jason; Gerhardt, Michael; Powers, Christopher M

2016-01-01

Previous studies have indicated that hip and pelvis kinematics may be altered during functional tasks in persons with femoroacetabular impingement. The purpose of this study was to compare hip and pelvis kinematics and kinetics during a deep squat task between persons with cam femoroacetabular impingement and pain-free controls. Fifteen persons with cam femoroacetabular impingement and 15 persons without cam femoroacetabular impingement performed a deep squat task. Peak hip flexion, abduction, and internal rotation, and mean hip extensor, adductor, and external rotator moments were quantified. Independent t-tests (α<0.05) were used to evaluate between group differences. Compared to the control group, persons with cam femoroacetabular impingement demonstrated decreased peak hip internal rotation (15.2° (SD 9.5°) vs. 9.4° (SD 7.8°); P=0.041) and decreased mean hip extensor moments (0.56 (SD 0.12) Nm/kg vs. 0.45 (SD 0.15) Nm/kg; P=0.018). In addition persons in the cam femoroacetabular impingement group demonstrated decreased posterior pelvis tilt during squat descent compared to the control group, resulting in a more anteriorly tilted pelvis at the time peak hip flexion (12.5° (SD 17.1°) vs. 23.0° (SD 12.4°); P=0.024). The decreased hip internal rotation observed in persons with cam femoroacetabular impingement may be the result of bony impingement. Furthermore, the decrease in posterior pelvis tilt may contribute to impingement by further approximating the femoral head-neck junction with the acetabulum. Additionally, decreased hip extensor moments suggest that diminished hip extensor muscle activity may contribute to decreased posterior pelvis tilt. Copyright © 2015 Elsevier Ltd. All rights reserved.

The cam impinging femur has multiple morphologic abnormalities.

PubMed

Ellis, Andrew R; Noble, Philip C; Schroder, Steven J; Thompson, Matthew T; Stocks, Gregory W

2011-09-01

This study was performed to establish whether the "cam" impinging femur has a single deformity of the head-neck junction or multiple abnormalities. Average dimensions (anteversion angle, α angle of Notzli, β angle of Beaulé, normalized anterior head offset) were compared between normal and impinging femora. The results demonstrated that impinging femora had wider necks, larger heads, and decreased head-neck ratios. There was no difference in neck-shaft angle or anteversion angle. Forty-six percent of impinging femora had significant posterior head displacement (>2mm), which averaged 1.93 mm for the cam impinging group, and 0.78 mm for the normal group. In conclusion, surgical treatment limited to localized recontouring of the head-neck profile may fail to address significant components of the underlying abnormality. Copyright © 2011 Elsevier Inc. All rights reserved.

Trailing edge cooling using angled impingement on surface enhanced with cast chevron arrangements

DOEpatents

Lee, Ching-Pang; Heneveld, Benjamin E.; Brown, Glenn E.; Klinger, Jill

2015-05-26

A gas turbine engine component, including: a pressure side (12) having an interior surface (34); a suction side (14) having an interior surface (36); a trailing edge portion (30); and a plurality of suction side and pressure side impingement orifices (24) disposed in the trailing edge portion (30). Each suction side impingement orifice is configured to direct an impingement jet (48) at an acute angle (52) onto a target area (60) that encompasses a tip (140) of a chevron (122) within a chevron arrangement (120) formed in the suction side interior surface. Each pressure side impingement orifice is configured to direct an impingement jet at an acute angle onto an elongated target area that encompasses a tip of a chevron within a chevron arrangement formed in the pressure side interior surface.

Clinical application of arthroscopy in the diagnosis and treatment of anterior impingement syndrome of the ankle joint in physical workers.

PubMed

Wu, Wen-Te; Chen, Zhi-Wei; Zhou, Yu-Cheng

2012-10-01

To evaluate the clinical application of arthroscopy in the diagnosis and treatment of anterior impingement syndrome of the ankle joint in physical workers. A retrospective study was carried out at the Department of Orthopedics, the First Hospital affiliated to Nanhua University, Hengyang, China from March 2005 to December 2011. Seventeen cases of anterior impingement syndrome of the ankle joint were confirmed, and treated through arthroscopy. All these patients conformed to regular follow-up postoperatively, and clinical details, as well as postoperative prognosis were retrieved and analyzed retrospectively. The efficacy was evaluated by the American Orthopedic Foot and Ankle Society (AOFAS) hindfoot-ankle scoring system, and pain relief was assessed by visual analogue scoring (VAS). Anterolateral impingement syndrome was found in 11 patients, anteromedial impingement syndrome in 4, while anterior impingement syndrome in 2 via arthroscopic examination. The VAS was reduced from 5.2-1.1, and the AOFAS score was elevated from 76.4-95.8 postoperatively; both of which demonstrated statistical differences when compared to preoperative scores. It was also found that concomitant cartilage damage was an indicator of poor prognosis in arthroscopic treatment of impingement syndrome of the ankle joint. Satisfactory results could be achieved for physical workers with anterior impingement syndrome treated by arthroscopy. As the cartilage damage is an indicator of poor prognosis, an early operation is advocated when the prognosis of anterior impingement syndrome is confirmed.

Mixed-type femoroacetabular impingement associated with subspine impingement: recognizing the trifocal femoropelvic impingement.

PubMed

Souza, Bruno Gonçalves Schröder E; Cardoso, Ranieri Monteiro; Loque, Rodrigo Silva; Monte, Luiz Fernando Ribeiro; Sabino, José Paulo; Oliveira, Valdeci Manoel de

2018-01-01

To describe the arthroscopic surgical technique for subspine impingement (SSI) of the anterior inferior iliac spine (AIIS) associated with mixed type femoroacetabular impingement (FAI), through two standard arthroscopic portals (anterolateral and distal mid-anterior) in two patients with trifocal impingement. The authors report the cases of two young male patients, aged 32 and 36 years old, with trifocal femoropelvic impingement (TFPI). The technique consists of segmental capsulectomy, arthroscopic dissection of the AIIS, partial release of the direct head of the rectus femoris, resection of the AIIS projection with a burr and with fluoroscopic aid, correction of the pincer deformity, repair of the labrum with bioabsorbable anchors, and femoral osteoplasty. Details of the diagnostic workup and of the surgical technique are provided and discussed. In these cases, full range of motion was regained after surgery, as well as complete relief of pain, which was sustained in the last follow-up, one year post-operatively. Radiographs show adequate correction of the deformities in all three impingement sites. Simultaneous correction of the three sites (cam, pincer, and subspinal) provided full relief of symptoms and allowed return to work and sports. The authors propose that when approaching the symptomatic SSI, the possibility of concomitant FAI should always be considered and, in those cases, the approach must be comprehensive.

Jet array impingement with crossflow-correlation of streamwise resolved flow and heat transfer distributions

NASA Technical Reports Server (NTRS)

Florschuetz, L. W.; Metzger, D. E.; Truman, C. R.

1981-01-01

Correlations for heat transfer coefficients for jets of circular offices and impinging on a surface parallel to the jet orifice plate are presented. The air, following impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer (impingement) surface. The downstream jets are subjected to a crossflow originating from the upstream jets. Impingement surface heat transfer coefficients resolved to one streamwise jet orifice spacing, averaged across the channel span, are correlated with the associated individual spanwise orifice row jet and crossflow velocities, and with the geometric parameters.

Impingement of Water Droplets on NACA 65A004 Airfoil and Effect of Change in Airfoil Thickness from 12 to 4 Percent at 4 deg Angle of Attack

NASA Technical Reports Server (NTRS)

Brun, Rinaldo J.; Gallagher, Helen M.; Vogt, Dorothea E.

1953-01-01

The trajectories of droplets in the air flowing past an NACA 65A004 a irfoil at an angle of attack of 4 deg were determined. The amount of water in droplet form impinging on the airfoil, the area of droplet impingement, and the rate of droplet impingement per unit area on the airfoil surface were calculated from the trajectories and presented to cover a large range of flight and atmospheric conditions. The effect of a change in airfoil thickness from 12 to 4 percent at 4 deg angle of attack is presented by comparing the impingement calculations for the NACA 65A004 airfoil with those for the NACA 65(sub 1)-208 and 65(sub 1)-212 airfoils. The rearward limit of impingement on the upper surface decreases as the airfoil thickness decreases. The rearward limit of impingement on the lower surface increases with a decrease in airfoil t hickness. The total water intercepted decreases as the airfoil thickness is decreased.

Supersonic impinging jet noise reduction using a hybrid control technique

NASA Astrophysics Data System (ADS)

Wiley, Alex; Kumar, Rajan

2015-07-01

Control of the highly resonant flowfield associated with supersonic impinging jet has been experimentally investigated. Measurements were made in the supersonic impinging jet facility at the Florida State University for a Mach 1.5 ideally expanded jet. Measurements included unsteady pressures on a surface plate near the nozzle exit, acoustics in the nearfield and beneath the impingement plane, and velocity field using particle image velocimetry. Both passive control using porous surface and active control with high momentum microjet injection are effective in reducing nearfield noise and flow unsteadiness over a range of geometrical parameters; however, the type of noise reduction achieved by the two techniques is different. The passive control reduces broadband noise whereas microjet injection attenuates high amplitude impinging tones. The hybrid control, a combination of two control methods, reduces both broadband and high amplitude impinging tones and surprisingly its effectiveness is more that the additive effect of the two control techniques. The flow field measurements show that with hybrid control the impinging jet is stabilized and the turbulence quantities such as streamwise turbulence intensity, transverse turbulence intensity and turbulent shear stress are significantly reduced.

Noise Characteristics of a Four-Jet Impingement Device Inside a Broadband Engine Noise Simulator

NASA Technical Reports Server (NTRS)

Brehm, Christoph; Housman, Jeffrey A.; Kiris, Cetin C.; Hutcheson, Florence V.

2015-01-01

The noise generation mechanisms for four directly impinging supersonic jets are investigated employing implicit large eddy simulations with a higher-order accurate weighted essentially non-oscillatory shock-capturing scheme. Impinging jet devices are often used as an experimental apparatus to emulate a broadband noise source. Although such devices have been used in many experiments, a detailed investigation of the noise generation mechanisms has not been conducted before. Thus, the underlying physical mechanisms that are responsible for the generation of sound waves are not well understood. The flow field is highly complex and contains a wide range of temporal and spatial scales relevant for noise generation. Proper orthogonal decomposition of the flow field is utilized to characterize the unsteady nature of the flow field involving unsteady shock oscillations, large coherent turbulent flow structures, and the sporadic appearance of vortex tubes in the center of the impingement region. The causality method based on Lighthill's acoustic analogy is applied to link fluctuations of flow quantities inside the source region to the acoustic pressure in the far field. It will be demonstrated that the entropy fluctuation term in the Lighthill's stress tensor plays a vital role in the noise generation process. Consequently, the understanding of the noise generation mechanisms is employed to develop a reduced-order linear acoustic model of the four-jet impingement device. Finally, three linear acoustic FJID models are used as broadband noise sources inside an engine nacelle and the acoustic scattering results are validated against far-field acoustic experimental data.

Ultra-high-speed 3D astigmatic particle tracking velocimetry: application to particle-laden supersonic impinging jets

NASA Astrophysics Data System (ADS)

Buchmann, N. A.; Cierpka, C.; Kähler, C. J.; Soria, J.

2014-11-01

The paper demonstrates ultra-high-speed three-component, three-dimensional (3C3D) velocity measurements of micron-sized particles suspended in a supersonic impinging jet flow. Understanding the dynamics of individual particles in such flows is important for the design of particle impactors for drug delivery or cold gas dynamic spray processing. The underexpanded jet flow is produced via a converging nozzle, and micron-sized particles ( d p = 110 μm) are introduced into the gas flow. The supersonic jet impinges onto a flat surface, and the particle impact velocity and particle impact angle are studied for a range of flow conditions and impingement distances. The imaging system consists of an ultra-high-speed digital camera (Shimadzu HPV-1) capable of recording rates of up to 1 Mfps. Astigmatism particle tracking velocimetry (APTV) is used to measure the 3D particle position (Cierpka et al., Meas Sci Technol 21(045401):13, 2010) by coding the particle depth location in the 2D images by adding a cylindrical lens to the high-speed imaging system. Based on the reconstructed 3D particle positions, the particle trajectories are obtained via a higher-order tracking scheme that takes advantage of the high temporal resolution to increase robustness and accuracy of the measurement. It is shown that the particle velocity and impingement angle are affected by the gas flow in a manner depending on the nozzle pressure ratio and stand-off distance where higher pressure ratios and stand-off distances lead to higher impact velocities and larger impact angles.

Impingement of Water Droplets on a Sphere

NASA Technical Reports Server (NTRS)

Dorsch, Robert G.; Saper, Paul G.; Kadow, Charles F.

1955-01-01

Droplet trajectories about a sphere in ideal fluid flow were calculated. From the calculated droplet trajectories the droplet impingement characteristics of the sphere were determined. Impingement data and equations for determining the collection efficiency, the area, and the distribution of impingement are presented in terms of dimensionless parameters. The range of flight and atmospheric conditions covered in the calculations was extended considerably beyond the range covered by previously reported calculations for the sphere.

Cryogenic Impinging Jets Subjected to High Frequency Transverse Acoustic Forcing in a High Pressure Environment

DTIC Science & Technology

2016-07-27

for liquid propellant atomization in rocket engines1- 2. Liquid rocket engines like the F-1 have successfully used like-on-like impinging jet...impingement of the two cylindrical jets. Another drawback, perhaps the most critical, is that rocket engine using impinging jets sacrifice performance in...The experimental results also suggested that impact waves seem to dominate the atomization process over most of the conditions relevant to rocket

Active Control of Supersonic Impinging Jets Using Supersonic Microjets

DTIC Science & Technology

2005-01-01

Impinging Jets using Supersonic Microjets 5b. GRANT NUMBER F49620-03-1-0017 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Farrukh Alvi 5e. TASK...investigation on the use of microjets for the control of supersonic impinging jets was conducted under this research program. Supersonic impinging...aircraft structures and the landing surfaces. Prior research has shown that microjets , placed around the main jet periphery, are very effective in

Modular jet impingement assemblies with passive and active flow control for electronics cooling

DOEpatents

Zhou, Feng; Dede, Ercan Mehmet; Joshi, Shailesh

2016-09-13

Power electronics modules having modular jet impingement assembly utilized to cool heat generating devices are disclosed. The modular jet impingement assemblies include a modular manifold having a distribution recess, one or more angled inlet connection tubes positioned at an inlet end of the modular manifold that fluidly couple the inlet tube to the distribution recess and one or more outlet connection tubes positioned at an outlet end of the modular manifold that fluidly coupling the outlet tube to the distribution recess. The modular jet impingement assemblies include a manifold insert removably positioned within the distribution recess and include one or more inlet branch channels each including an impinging slot and one or more outlet branch channels each including a collecting slot. Further a heat transfer plate coupled to the modular manifold, the heat transfer plate comprising an impingement surface including an array of fins that extend toward the manifold insert.

Impingement of Cloud Droplets on 36.5-Percent-Thick Joukowski Airfoil at Zero Angle of Attack and Discussion of Use as Cloud Measuring Instrument in Dye-Tracer Technique

NASA Technical Reports Server (NTRS)

Brun, R. J.; Vogt, Dorothea E.

1957-01-01

The trajectories of droplets i n the air flowing past a 36.5-percent-thick Joukowski airfoil at zero angle of attack were determined. The amount of water i n droplet form impinging on the airfoil, the area of droplet impingement, and the rate of droplet impingement per unit area on the airfoil surface were calculated from the trajectories and cover a large range of flight and atmospheric conditions. With the detailed impingement information available, the 36.5-percent-thick Joukowski airfoil can serve the dual purpose of use as the principal element in instruments for making measurements in clouds and of a basic shape for estimating impingement on a thick streamlined body. Methods and examples are presented for illustrating some limitations when the airfoil is used as the principal element in the dye-tracer technique.

Magnetic Resonance Velocimetry analysis of an angled impinging jet

NASA Astrophysics Data System (ADS)

Irhoud, Alexandre; Benson, Michael; Verhulst, Claire; van Poppel, Bret; Elkins, Chris; Helmer, David

2016-11-01

Impinging jets are used to achieve high heat transfer rates in applications ranging from gas turbine engines to electronics. Despite the importance and relative simplicity of the geometry, simulations historically fail to accurately predict the flow behavior in the vicinity of the flow impingement. In this work, we present results from a novel experimental technique, Magnetic Resonance Velocimetry (MRV), which measures three-dimensional time-averaged velocity without the need for optical access. The geometry considered in this study is a circular jet angled at 45 degrees and impinging on a flat plate, with a separation of approximately seven jet diameters between the jet exit and the impingement location. Two flow conditions are considered, with Reynolds numbers of roughly 800 and 14,000. Measurements from the MRV experiment are compared to predictions from Reynolds Averaged Navier Stokes (RANS) simulations, thus demonstrating the utility of MRV for validation of numerical analyses of impinging jet flow.

Drop Impingement on Highly Wetting Micro/Nano Porous Surfaces

NASA Astrophysics Data System (ADS)

Buie, Cullen; Joung, Youngsoo

2011-11-01

Recently, we developed a novel fabrication method using a combination of electrophoretic deposition (EPD) and break down anodization (BDA) to achieve highly wetting nanoporous surfaces with microscale features. In this study we investigate droplet impingement behavior on these surfaces as a function of impact velocity, droplet size, and liquid properties. We observe impingement modes we denote as ``necking'' (droplet breaks before full penetration in the porous surface), ``spreading'' (continuous wicking into the porous surface), and ``jetting'' (jets of liquid emanate from the edges of the wicking liquid). To predict the droplet impingement modes, we've developed a non-dimensional parameter that is a function of droplet velocity, dynamic viscosity, effective pore radius and contact angle. The novel dimensionless parameter successfully predicts drop impingement modes across multiple fluids. Results of this study will inform the design of spray impingement cooling systems for electronics applications where the ``spreading'' mode is preferred.

Regeneratively cooled transition duct with transversely buffered impingement nozzles

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

Morrison, Jay A; Lee, Ching-Pang; Crawford, Michael E

2015-04-21

A cooling arrangement (56) having: a duct (30) configured to receive hot gases (16) from a combustor; and a flow sleeve (50) surrounding the duct and defining a cooling plenum (52) there between, wherein the flow sleeve is configured to form impingement cooling jets (70) emanating from dimples (82) in the flow sleeve effective to predominately cool the duct in an impingement cooling zone (60), and wherein the flow sleeve defines a convection cooling zone (64) effective to cool the duct solely via a cross-flow (76), the cross-flow comprising cooling fluid (72) exhausting from the impingement cooling zone. In themore » impingement cooling zone an undimpled portion (84) of the flow sleeve tapers away from the duct as the undimpled portion nears the convection cooling zone. The flow sleeve is configured to effect a greater velocity of the cross-flow in the convection cooling zone than in the impingement cooling zone.« less

Experimental, water droplet impingement data on two-dimensional airfoils, axisymmetric inlet and Boeing 737-300 engine inlet

NASA Technical Reports Server (NTRS)

Papadakis, M.; Elangovan, E.; Freund, G. A., Jr.; Breer, M. D.

1987-01-01

An experimental method has been developed to determine the droplet impingement characteristics on two- and three-dimensional bodies. The experimental results provide the essential droplet impingement data required to validate particle trajectory codes, used in aircraft icing analyses and engine inlet particle separator analyses. A body whose water droplet impingement characteristics are required is covered at strategic locations by thin strips of moisture absorbing (blotter) paper, and then exposed to an air stream containing a dyed-water spray cloud. Water droplet impingement data are extracted from the dyed blotter strips, by measuring the optical reflectance of the dye deposit on the strips, using an automated reflectometer. Impingement efficiency data obtained for a NACA 65(2)015 airfoil section, a supercritical airfoil section, and Being 737-300 and axisymmetric inlet models are presented in this paper.

Impact of entrainment and impingement on fish populations in the Hudson River Estuary. Volume II. Impingement impact analyses, evaluations of alternative screening devices, and critiques of utility testimony relating to density-dependent growth, the age-composition of the striped bass spawning stock, and the LMS real-time life cycle model

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

Barnthouse, L. W.; Van Winkle, W.; Golumbek, J.

1982-04-01

This volume includes a series of four exhibits relating to impacts of impingement on fish populations, together with a collection of critical evaluations of testimony prepared for the utilities by their consultants. The first exhibit is a quantitative evaluation of four sources of bias (collection efficiency, reimpingement, impingement on inoperative screens, and impingement survival) affecting estimates of the number of fish killed at Hudson River power plants. The two following exhibits contain, respectively, a detailed assessment of the impact of impingement on the Hudson River white perch population and estimates of conditional impingement mortality rates for seven Hudson River fishmore » populations. The fourth exhibit is an evaluation of the engineering feasibility and potential biological effectiveness of several types of modified intake structures proposed as alternatives to cooling towers for reducing impingement impacts. The remainder of Volume II consists of critical evaluations of the utilities' empirical evidence for the existence of density-dependent growth in young-of-the-year striped bass and white perch, of their estimate of the age-composition of the striped bass spawning stock in the Hudson River, and of their use of the Lawler, Matusky, and Skelly (LMS) Real-Time Life Cycle Model to estimate the impact of entrainment and impingement on the Hudson River striped bass population.« less

Impingement.

ERIC Educational Resources Information Center

Uziel, Mary S.

1978-01-01

Presents a literature review of the impact of impingement in fishery resources at different power plants in the United States, covering publications of 1976-77. Consideration is given to engineering studies and biological effects for reducing impingement. A list of 96 references is also presented. (HM)

Ultrasound elastography-based assessment of the elasticity of the supraspinatus muscle in impingement syndrome: does elastography has any diagnostic value?

PubMed

Demirel, Adnan; Baykara, Murat; Koca, Tuba Tülay; Berk, Ejder

2018-06-01

Ultrasound elastography (UE) is a new ultrasound-based imaging technique that provides information about elasticity and stiffness of tissues. This cross-sectional study aimed to identify the diagnostic importance of UE in supraspinatus impingement syndrome. Forty-one subjects, aged 38-70 years, were included in the study. UE was used to determine the elasticity of the supraspinatus muscle. The strain ratio was calculated as the evaluation criteria to measure the elasticity of the muscle. High strain ratio indicated low elasticity. The measurements were made by the blinded radiologist while the patients sat with their shoulder in a neutral position. The diagnostic value of the strain ratio was evaluated using the receiver operating characteristic (ROC) analysis. The mean strain value of the supraspinatus muscle on the intact and pathological shoulders determined by UE was 0.74 ± 0.33 and 0.31 ± 0.24, respectively. A low strain ratio value in the supraspinatus muscle on the side with impingement syndrome was measured. When the test variable was evaluated as "strain ratio" according to ROC curve analysis, it was found to be above the reference line [0.849 (> 0.5)] (P = 0.00). When the cutoff value was selected as 0.495, the sensitivity and specificity were found to be 75.6 and 78% (the strain ratio value > 0.495), respectively. Measurement of strain ratio with UE can be used as a noninvasive, inexpensive, and practical diagnostic test for the shoulder impingement disease.

Outdoor Performance Analysis of a Photovoltaic Thermal (PVT) Collector with Jet Impingement and Compound Parabolic Concentrator (CPC)

PubMed Central

Jaaz, Ahed Hameed; Hasan, Husam Abdulrasool; Sopian, Kamaruzzaman; Kadhum, Abdul Amir H.; Gaaz, Tayser Sumer

2017-01-01

This paper discusses the effect of jet impingement of water on a photovoltaic thermal (PVT) collector and compound parabolic concentrators (CPC) on electrical efficiency, thermal efficiency and power production of a PVT system. A prototype of a PVT solar water collector installed with a jet impingement and CPC has been designed, fabricated and experimentally investigated. The efficiency of the system can be improved by using jet impingement of water to decrease the temperature of the solar cells. The electrical efficiency and power output are directly correlated with the mass flow rate. The results show that electrical efficiency was improved by 7% when using CPC and jet impingement cooling in a PVT solar collector at 1:00 p.m. (solar irradiance of 1050 W/m2 and an ambient temperature of 33.5 °C). It can also be seen that the power output improved by 36% when using jet impingement cooling with CPC, and 20% without CPC in the photovoltaic (PV) module at 1:30 p.m. The short-circuit current ISC of the PV module experienced an improvement of ~28% when using jet impingement cooling with CPC, and 11.7% without CPC. The output of the PV module was enhanced by 31% when using jet impingement cooling with CPC, and 16% without CPC. PMID:28763048

Analysis of Impingement between Patella Bone and Bearing Post in Cruciate-Substituting High-Flexion Total Knee Arthroplasty

PubMed Central

Chon, Jegyun; Shin, Sangyeop; Jang, Gunil; Jeon, Taehyeon

2016-01-01

Background We investigated the causes of impingement between the patella bone and the bearing post during high flexion in cruciate-substituting total knee arthroplasty and proposed a treatment strategy. Methods This prospective cohort study included 218 cases that had undergone cruciate-substituting total knee arthroplasty from February 2014 to January 2015; a single surgeon performed the operation using the same method without patellar resurfacing in all patients. Results In these patients, the occurrence of impingement was determined by performing more than 120° high knee flexion after inserting a bearing perioperatively. The incidence of impingement was significantly associated with bearing design, femoral implant size, patella bone length, and patella inferior pole angle (p < 0.05). The impingement was resolved by resection of the lower articular side of the patella bone. Conclusions In the cruciate-substituting high-flexion total knee arthroplasty, impingement between the patella bone and bearing post was more common in patients with mobile bearing, small-size femoral component, and a long patella or a large inferior pole angle. In cases of intraoperative impingement between the patella bone and the bearing post, resection in the lower portion of the patella prevented impingement of the bearing with soft tissue or the patella by widening the space between the patella and the bearing post, which in turn prevented postoperative reduction in range of motion. PMID:27247740

Outdoor Performance Analysis of a Photovoltaic Thermal (PVT) Collector with Jet Impingement and Compound Parabolic Concentrator (CPC).

PubMed

Jaaz, Ahed Hameed; Hasan, Husam Abdulrasool; Sopian, Kamaruzzaman; Kadhum, Abdul Amir H; Gaaz, Tayser Sumer; Al-Amiery, Ahmed A

2017-08-01

This paper discusses the effect of jet impingement of water on a photovoltaic thermal (PVT) collector and compound parabolic concentrators (CPC) on electrical efficiency, thermal efficiency and power production of a PVT system. A prototype of a PVT solar water collector installed with a jet impingement and CPC has been designed, fabricated and experimentally investigated. The efficiency of the system can be improved by using jet impingement of water to decrease the temperature of the solar cells. The electrical efficiency and power output are directly correlated with the mass flow rate. The results show that electrical efficiency was improved by 7% when using CPC and jet impingement cooling in a PVT solar collector at 1:00 p.m. (solar irradiance of 1050 W/m² and an ambient temperature of 33.5 °C). It can also be seen that the power output improved by 36% when using jet impingement cooling with CPC, and 20% without CPC in the photovoltaic (PV) module at 1:30 p.m. The short-circuit current I SC of the PV module experienced an improvement of ~28% when using jet impingement cooling with CPC, and 11.7% without CPC. The output of the PV module was enhanced by 31% when using jet impingement cooling with CPC, and 16% without CPC.

Analysis of Impingement between Patella Bone and Bearing Post in Cruciate-Substituting High-Flexion Total Knee Arthroplasty.

PubMed

Chon, Jegyun; Lee, Bongju; Shin, Sangyeop; Jang, Gunil; Jeon, Taehyeon

2016-06-01

We investigated the causes of impingement between the patella bone and the bearing post during high flexion in cruciate-substituting total knee arthroplasty and proposed a treatment strategy. This prospective cohort study included 218 cases that had undergone cruciate-substituting total knee arthroplasty from February 2014 to January 2015; a single surgeon performed the operation using the same method without patellar resurfacing in all patients. In these patients, the occurrence of impingement was determined by performing more than 120° high knee flexion after inserting a bearing perioperatively. The incidence of impingement was significantly associated with bearing design, femoral implant size, patella bone length, and patella inferior pole angle (p < 0.05). The impingement was resolved by resection of the lower articular side of the patella bone. In the cruciate-substituting high-flexion total knee arthroplasty, impingement between the patella bone and bearing post was more common in patients with mobile bearing, small-size femoral component, and a long patella or a large inferior pole angle. In cases of intraoperative impingement between the patella bone and the bearing post, resection in the lower portion of the patella prevented impingement of the bearing with soft tissue or the patella by widening the space between the patella and the bearing post, which in turn prevented postoperative reduction in range of motion.

Proceedings of the International Congress (12th), Corrosion Control for Low-Cost Reliability, Held in Houston, Texas on September 19 -24, 1993. Volume 6. Electric Power Industry

DTIC Science & Technology

1993-09-24

Protection 567 Passivity of Carbon Steel in Organic Solutions in the Presence of Iron Bacteria 0. Schifler, P. Moran, and j. Kruger...under Impingement Attack 190 Anaerobic Corrosion of Steel by Phototrophic Sulfur Bacteria M. Reda and J. Alhalji...of Sulfate Reducing Bacteria in Western Canadian Oil Field Fluids K. Hashimoto, S. Kato, B. In, E. Akiyama, H. Habakazi, A. D. Westlake, I. Foght, P

Aircraft Emissions Characterization: TF41-A2, TF30-P103, and TF30-P109 Engines

DTIC Science & Technology

1987-12-01

impingers containing 2,4- dinitrophenylhydrazine (DNPH), wherein the DNPH derivatives are formed. The derivatives were returned to the 11 laboratory, extracted...a solution consisting of 250 mg of 2,4- dinitrophenylhydrazine and 0.2 mL of 98 percent sulfuric acid dissolved in 1 liter of acetonitrile (ACCN... Dinitrophenylhydrazine Method," J. Chrom., 247, 297-306 (1982). 11. Zweidinger, R. B., ’Emission Factors from Diesel and Gasoline Powered Vehicles: Correlation With the

Nonlinear Analysis of Airfoil High-Intensity Gust Response Using a High-Order Prefactored Compact Code

NASA Technical Reports Server (NTRS)

Crivellini, A.; Golubev, V.; Mankbadi, R.; Scott, J. R.; Hixon, R.; Povinelli, L.; Kiraly, L. James (Technical Monitor)

2002-01-01

The nonlinear response of symmetric and loaded airfoils to an impinging vortical gust is investigated in the parametric space of gust dimension, intensity, and frequency. The study, which was designed to investigate the validity limits for a linear analysis, is implemented by applying a nonlinear high-order prefactored compact code and comparing results with linear solutions from the GUST3D frequency-domain solver. Both the unsteady aerodynamic and acoustic gust responses are examined.

Investigation of 3D Shock-Boundary Layer Interaction: A Combined Approach using Experiments, Numerical Simulations and Stability Analysis

DTIC Science & Technology

2015-12-02

layer , the non-reflecting boundary condition suggested by Poinsot and Lele is adopted.38 On the flat – plate surface, the no-penetration (v = 0) and the no...generator plate is emulated to create an oblique shock that impinges on the boundary layer causing separation. This is similar to the experimental...without SBLI and with SBLI. To calculate the steady flat – plate solution with no shock, a characteristic boundary condition according to Harris is used.39

Heat Transfer Prediction of Film Cooling in Supersonic Flow

NASA Astrophysics Data System (ADS)

Luchi, Riccardo; Salvadori, Simone; Martelli, Francesco

2008-09-01

Considering the modern high pressure stages of gas turbines, the flow over the suction side of the blades can be affected by the presence of shock impingement and boundary layer separation. Furthermore, it should be pointed out that the combustor exit temperature reaches values which are close to the allowable material limit. Then, a cooling system based on the film cooling approach should be designed to prevent failure. The interaction between the ejected coolant and the shock impingement must be studied to achieve a higher efficiency of the cooling system. The proposed approach is based on the numerical evaluation of a film cooled test section experimentally studied at the University of Karlsruhe. The testing rig consists in a converging-diverging nozzle that accelerates the flow up to sonic conditions while an oblique shock is generated at the nozzle exit section. Three cases have been studied, changing the cooling holes position with respect to the shock impingement over the cooled surface. The obtained results are presented and compared with the experimental data. The used solver is the in-house CFD 3D code HybFlow, developed at the University of Florence. This study has been carried out in the frame of the EU funded TATEF2 project.

What is the impingement-free range of motion of the asymptomatic hip in young adult males?

PubMed

Larkin, Brian; van Holsbeeck, Marnix; Koueiter, Denise; Zaltz, Ira

2015-04-01

Femoroacetabular impingement is a recognized cause of chondrolabral injury. Although surgical treatment for impingement seeks to improve range of motion, there are very little normative data on dynamic impingement-free hip range of motion (ROM) in asymptomatic people. Hip ultrasound demonstrates labral anatomy and femoral morphology and, when used dynamically, can assist in measuring range of motion. The purposes of this study were (1) to measure impingement-free hip ROM until labral deflection is observed; and (2) to measure the maximum degree of sagittal plane hip flexion when further flexion is limited by structural femoroacetabular abutment. Forty asymptomatic adult male volunteers (80 hips) between the ages of 21 and 35 years underwent bilateral static and dynamic hip ultrasound examination. Femoral morphology was characterized and midsagittal flexion passive ROM was measured at two points: (1) at the initiation of labral deformation; and (2) at maximum flexion when the femur impinged on the acetabular rim. The mean age of the subjects was 28 ± 3 years and the mean body mass index was 25 ± 4 kg/m(2). Mean impingement-free hip passive flexion measured from full extension to initial labral deflection was 68° ± 17° (95% confidence interval [CI], 65-72). Mean maximum midsagittal passive flexion, measured at the time of bony impingement, was 96° ± 6° (95% CI, 95-98). Using dynamic ultrasound, we found that passive ROM in the asymptomatic hip was much less than the motion reported in previous studies. Measuring ROM using ultrasound is more accurate because it allows anatomic confirmation of terminal hip motion. Surgical procedures used to treat femoroacetabular impingement are designed to restore or increase hip ROM and their results should be evaluated in light of precise normative data. This study suggests that normal passive impingement-free femoroacetabular flexion in the young adult male is approximately 95°.

Hydrodynamics and PIV study in the impingement zone formed by a droplet train

NASA Astrophysics Data System (ADS)

Kanjirakat, Anoop; Sadr, Reza; Zhang, Taolue; Muthusamy, Jayaveera; Alvarado, Jorge; Texas A; M University at Qatar Collaboration; Texas A; M University College Station Collaboration

2016-11-01

Droplet impingement is encountered in numerous technical applications, such as ink jet printing, spray cooling, and fuel injection in internal combustion engines. Even though many studies in droplet impingement were conducted in past, not many have measured the near-wall velocities in the droplet impingement zone. With the goal of gaining a better understanding of the hydrodynamics in the impingement zone, well-controlled experiments are performed in combination with micro-PIV measurements and numerical simulations. Hydrodynamics of HFE-7100 droplets generated using a piezoelectric droplet generator, impinging on a pre-wetted surface is investigated. Micro-PIV studies in the high-velocity impingement zone are performed using one-micron meter fluorescent particles dispersed in HFE-7100 along with the double exposed images. Three-dimensional and 2D-axisymmetric numerical modeling for a transient droplet crown development is performed. The interface between the gas and the liquid is modeled using a Volume of Fluid (VOF) method. Numerical simulation results obtained are observed to be in good agreement with that of the experimental observations. Supported by National Priority Research Program (NPRP) of Qatar National Research Fund (QNRF), Grant No.: NPRP 6-1304-2-525.

Factors influencing impingement of fish by Lake Ontario power plants

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

Wyman, R.L.; Dischel, R.S.

1984-01-01

Fish impinged by two Lake Ontario power plants were examined to determine the causal factors. Fish were near shore because they resided there, migrated there to spawn or forage, or because the water mass in which they resided moved near shore. Once near shore, fish abundance in impingement collections was correlated with demersal or pelagic behavior. Periodic increases in diversity and abundance of impinged fish corresponded with times of upwelling and thermocline oscillations. These data suggest that some species were segregated along temperature gradients and were impinged when the thermocline passed near the intake. Comparisons of impingement catch between twomore » power plants, one withdrawing a constant volume of water and the other a varying volume, showed that responses of fish to an intake were of three kinds. Alosa pseudoharengus and Osmerus mordax were apparently attracted to water currents entering the intake. Morone americana, Morone chrysops, Dorosoma cepedianum, and Perca flavescens were not influenced by changes in flow rate, suggesting that their impingement was proportional to their density in nearshore water. Micropterus dolomieui avoided the intake at higher flow rates in part due to rheotactic behavior. 25 references, 4 figures, 3 table.« less

Can hip impingement be mistaken for tendon pain in the groin? A long-term follow-up of tenotomy for groin pain in athletes.

PubMed

Sansone, Mikael; Ahldén, Mattias; Jonasson, Pall; Thomeé, Roland; Falk, Anders; Swärd, Leif; Karlsson, Jón

2014-04-01

There are several reports on the association between pubalgia and intra-articular hip disorders. The purpose of this study was to evaluate the long-term outcome in athletes who underwent tenotomy due to long-standing groin pain. A secondary purpose was evaluating the frequency of femoro-acetabular impingement (FAI) and its impact on the long-term outcome. Thirty-two high-level male athletes treated with adductor tenotomy, rectus abdominis tenotomy or both were included. At a median follow-up time of 6 years after the tenotomy, the subjects underwent standardised clinical examination, plain radiographs, completed web-based health-related patient-reported outcomes, including iHOT12, HAGOS (six subscales), EQ-5D (two subscales), HSAS for physical activity level and a VAS for overall hip function. Furthermore, patient satisfaction and return to sports were documented. Twenty-four of the 32 (75 %) athletes were satisfied with the outcome of the tenotomy, and 22 of the athletes (69 %) were able to return to their pre-injury sport. Before the long-term follow-up, two of these satisfied athletes had undergone repeat surgery (one hip arthroscopy due to FAI and one repeat tenotomy). Of the 24 satisfied athletes, eight (33 %) had a positive hip impingement test at the follow-up. Of the remaining eight athletes not satisfied with the outcome, only one returned to their pre-injury sport and three had undergone hip arthroscopy prior to follow-up. Five had positive hip impingement tests which was significantly more frequently than in the satisfied group (p = 0.008). The group with a positive hip impingement test reported significantly more pain and symptoms, more hip problems during sports and physical activity, as well as lower hip-related quality of life according to the HAGOS scores (p < 0.05), at follow-up. Tenotomy for pubalgia yielded a satisfactory long-term outcome, with three of four athletes being able to return to their pre-injury sport. The athletes that did not return to their pre-injury sport had higher frequency of positive hip impingement test and inferior functional outcome compared with the athletes that did return to their pre-injury sport. It is therefore recommended that the hip should be carefully evaluated for hip impingement before tenotomy is considered as treatment for athletes with pubalgia.

An analysis of the booster plume impingement environment during the space shuttle nominal staging maneuver

NASA Technical Reports Server (NTRS)

Wojciechowski, C. J.; Penny, M. M.; Greenwood, T. F.; Fossler, I. H.

1972-01-01

An experimental study of the plume impingement heating on the space shuttle booster afterbody resulting from the space shuttle orbiter engine plumes was conducted. The 1/100-scale model tests consisted of one and two orbiter engine firings on a flat plate, a flat plate with a fin, and a cylinder model. The plume impingement heating rates on these surfaces were measured using thin film heat transfer gages. Results indicate the engine simulation is a reasonable approximation to the two engine configuration, but more tests are needed to verify the plume model of the main engine configuration. For impingment, results show models experienced laminar boundary layer convective heating. Therefore, tests at higher Reynolds numbers are needed to determine impingment heating.

Posterior ankle impingement in athletes: Pathogenesis, imaging features and differential diagnoses.

PubMed

Hayashi, Daichi; Roemer, Frank W; D'Hooghe, Pieter; Guermazi, Ali

2015-11-01

Posterior ankle impingement is a clinical diagnosis which can be seen following a traumatic hyper-plantar flexion event and may lead to painful symptoms in athletes such as female dancers ('en pointe'), football players, javelin throwers and gymnasts. Symptoms of posterior ankle impingement are due to failure to accommodate the reduced interval between the posterosuperior aspect of the talus and tibial plafond during plantar flexion, and can be due to osseous or soft tissue lesions. There are multiple causes of posterior ankle impingement. Most commonly, the structural correlates of impingement relate to post-traumatic synovitis and intra-articular fibrous bands-scar tissue, capsular scarring, or bony prominences. The aims of this pictorial review article is to describe different types of posterior ankle impingement due to traumatic and non-traumatic osseous and soft tissue pathology in athletes, to describe diagnostic imaging strategies of these pathologies, and illustrate their imaging features, including relevant differential diagnoses. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Experimental Water Droplet Impingement Data on Airfoils, Simulated Ice Shapes, an Engine Inlet and a Finite Wing

NASA Technical Reports Server (NTRS)

Papadakis, M.; Breer, M.; Craig, N.; Liu, X.

1994-01-01

An experimental method has been developed to determine the water droplet impingement characteristics on two- and three-dimensional aircraft surfaces. The experimental water droplet impingement data are used to validate particle trajectory analysis codes that are used in aircraft icing analyses and engine inlet particle separator analyses. The aircraft surface is covered with thin strips of blotter paper in areas of interest. The surface is then exposed to an airstream that contains a dyed-water spray cloud. The water droplet impingement data are extracted from the dyed blotter paper strips by measuring the optical reflectance of each strip with an automated reflectometer. Experimental impingement efficiency data represented for a NLF (1)-0414 airfoil, a swept MS (1)-0317 airfoil, a Boeing 737-300 engine inlet model, two simulated ice shapes and a swept NACA 0012 wingtip. Analytical impingement efficiency data are also presented for the NLF (1)-0414 airfoil and the Boeing 737-300 engine inlet model.

Particle trajectory computation on a 3-dimensional engine inlet. Final Report Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Kim, J. J.

1986-01-01

A 3-dimensional particle trajectory computer code was developed to compute the distribution of water droplet impingement efficiency on a 3-dimensional engine inlet. The computed results provide the essential droplet impingement data required for the engine inlet anti-icing system design and analysis. The droplet trajectories are obtained by solving the trajectory equation using the fourth order Runge-Kutta and Adams predictor-corrector schemes. A compressible 3-D full potential flow code is employed to obtain a cylindrical grid definition of the flowfield on and about the engine inlet. The inlet surface is defined mathematically through a system of bi-cubic parametric patches in order to compute the droplet impingement points accurately. Analysis results of the 3-D trajectory code obtained for an axisymmetric droplet impingement problem are in good agreement with NACA experimental data. Experimental data are not yet available for the engine inlet impingement problem analyzed. Applicability of the method to solid particle impingement problems, such as engine sand ingestion, is also demonstrated.

A Method for Determining Cloud-Droplet Impingement on Swept Wings

NASA Technical Reports Server (NTRS)

Dorsch, Robert G.; Brun, Rinaldo J.

1953-01-01

The general effect of wing sweep on cloud-droplet trajectories about swept wings of high aspect ratio moving at subsonic speeds is discussed. A method of computing droplet trajectories about yawed cylinders and swept wings is presented, and illustrative droplet trajectories are computed. A method of extending two-dimensional calculations of droplet impingement on nonswept wings to swept wings is presented. It is shown that the extent of impingement of cloud droplets on an airfoil surface, the total rate of collection of water, and the local rate of impingement per unit area of airfoil surface can be found for a swept wing from two-dimensional data for a nonswept wing. The impingement on a swept wing is obtained from impingement data for a nonswept airfoil section which is the same as the section in the normal plane of the swept wing by calculating all dimensionless parameters with respect to flow conditions in the normal plane of the swept wing.

Unusual case of mixed form of femoroacetabular impingement combined with nonspecific synovitis of the hip joint in a young adult-- A case report.

PubMed

Mladenović, Marko; Micić, Ivan; Andjelković, Zoran; Mladenović, Desimir; Stojiljković, Predrag

2015-12-01

Minimal bone changes in the acetabulum and/or proximal femur, through mechanism known as femoroacetabular impingement, during flexion, adduction and internal rotation lead to early contact between femoral head-neck junction and acetabular brim, in anterosuperior region. Each additional pathological substrate which further decreases specified clearance provokes earlier onset of femoroacetabular impingement symptoms. We presented a 20-year-old male patient with groin pain, limping, positive impingement test, radiological signs of mixed form of femoroacetabular impingement and unrecognized chronic hypertrophic synovitis with earlier development of clinical hip symptoms than it has been expected. Open surgery of the left hip was done. Two years after the surgery, patient was asymptomatic, painless, and free of motion, with stable x-rays. Hypertrophic synovial tissue further reduces the distance between the femoral head-neck junction and the acetabulum, leading to the earlier onset of femoroacetabular impingement symptoms. Surgical treatment is the method of choice.

ACL Roof Impingement Revisited: Does the Independent Femoral Drilling Technique Avoid Roof Impingement With Anteriorly Placed Tibial Tunnels?

PubMed

Tanksley, John A; Werner, Brian C; Conte, Evan J; Lustenberger, David P; Burrus, M Tyrrell; Brockmeier, Stephen F; Gwathmey, F Winston; Miller, Mark D

2017-05-01

Anatomic femoral tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is now well accepted. The ideal location for the tibial tunnel has not been studied extensively, although some biomechanical and clinical studies suggest that placement of the tibial tunnel in the anterior part of the ACL tibial attachment site may be desirable. However, the concern for intercondylar roof impingement has tempered enthusiasm for anterior tibial tunnel placement. To compare the potential for intercondylar roof impingement of ACL grafts with anteriorly positioned tibial tunnels after either transtibial (TT) or independent femoral (IF) tunnel drilling. Controlled laboratory study. Twelve fresh-frozen cadaver knees were randomized to either a TT or IF drilling technique. Tibial guide pins were drilled in the anterior third of the native ACL tibial attachment site after debridement. All efforts were made to drill the femoral tunnel anatomically in the center of the attachment site, and the surrogate ACL graft was visualized using 3-dimensional computed tomography. Reformatting was used to evaluate for roof impingement. Tunnel dimensions, knee flexion angles, and intra-articular sagittal graft angles were also measured. The Impingement Review Index (IRI) was used to evaluate for graft impingement. Two grafts (2/6, 33.3%) in the TT group impinged upon the intercondylar roof and demonstrated angular deformity (IRI type 1). No grafts in the IF group impinged, although 2 of 6 (66.7%) IF grafts touched the roof without deformation (IRI type 2). The presence or absence of impingement was not statistically significant. The mean sagittal tibial tunnel guide pin position prior to drilling was 27.6% of the sagittal diameter of the tibia (range, 22%-33.9%). However, computed tomography performed postdrilling detected substantial posterior enlargement in 2 TT specimens. A significant difference in the sagittal graft angle was noted between the 2 groups. TT grafts were more vertical, leading to angular convergence with the roof, whereas IF grafts were more horizontal and universally diverged from the roof. The IF technique had no specimens with roof impingement despite an anterior tibial tunnel position, likely due to a more horizontal graft trajectory and anatomic placement of the ACL femoral tunnel. Roof impingement remains a concern after TT ACL reconstruction in the setting of anterior tibial tunnel placement, although statistical significance was not found. Future clinical studies are planned to develop better recommendations for ACL tibial tunnel placement. Graft impingement due to excessively anterior tibial tunnel placement using a TT drilling technique has been previously demonstrated; however, this may not be a concern when using an IF tunnel drilling technique. There may also be biomechanical advantages to a more anterior tibial tunnel in IF tunnel ACL reconstruction.

Comparative analysis of arthroscopic debridement in osseous versus soft tissue anterior ankle impingement.

PubMed

Devgan, Ashish; Rohilla, Rajesh; Tanwar, Milind; Jain, Aditya; Siwach, Karan; Devgan, Radika

2016-01-01

Arthroscopic debridement has been a gold standard procedure for anterior ankle impingement, both in cases of osseous and soft tissue impingement. There is sparse literature on comparative outcome with respect to functional results between the two types of impingement post-arthroscopic debridement. Our study included 14 patients diagnosed as cases of anterior ankle impingement on the basis of clinical and radiological examination. They were segregated into two groups (on the basis of cause of impingement (osseous versus soft tissue)). Both groups were treated by arthroscopic debridement. Primary outcome was patient satisfaction, which was assessed by Likert scale and clinical outcomes were measured using AOFAS ankle-hind foot scale, VAS score, range of motion and time to return to pre-injury activity level in both groups. Mean follow-up was of 15 months where eleven patients reported an excellent recovery, two patients had good recovery while one patient reported poor outcome. Mean AOFAS ankle hind foot scale improved from 50.5 preoperatively to 85.71 postoperatively (statistically significant; p value - 0.0001). Mean Likert scale value post-operative was 4.21. VAS score showed significant improvement in patients of both the groups. Range of motion was slightly better in soft tissue impingement type with a relatively shorter time to return to sports or preinjury activity level as compared to osseous impingement group. The patients in both the groups had comparable outcomes with no statistically significant difference with regard to patient satisfaction and clinical outcome.

Intercondylar roof impingement pressure after anterior cruciate ligament reconstruction in a porcine model.

PubMed

Iriuchishima, Takanori; Tajima, Goro; Ingham, Sheila J M; Shen, Wei; Horaguchi, Takashi; Saito, Akiyoshi; Smolinski, Patrick; Fu, Freddie H

2009-06-01

Anterior cruciate ligament (ACL) graft impingement against the intercondylar roof has been postulated, but not thoroughly investigated. The roof impingement pressure changes with different tibial and femoral tunnel positions in ACL reconstruction. Anterior tibial translation is also affected by the tunnel positions of ACL reconstruction. The study design included a controlled laboratory study. In 15 pig knees, the impingement pressure between ACL and intercondylar roof was measured using pressure sensitive film before and after ACL single bundle reconstruction. ACL reconstructions were performed in each knee with two different tibial and femoral tunnel position combinations: (1) tibial antero-medial (AM) tunnel to femoral AM tunnel (AM to AM) and (2) tibial postero-lateral (PL) tunnel to femoral High-AM tunnel (PL to High-AM). Anterior tibial translation (ATT) was evaluated after each ACL reconstruction using robotic/universal force-moment sensor testing system. Neither the AM to AM nor the PL to High-AM ACL reconstruction groups showed significant difference when compared with intact ACL in roof impingement pressure. The AM to AM group had a significantly higher failure load than PL to High-AM group. This study showed how different tunnel placements affect the ACL-roof impingement pressure and anterior-posterior laxity in ACL reconstruction. Anatomical ACL reconstruction does not cause roof impingement and it has a biomechanical advantage in ATT when compared with non-anatomical ACL reconstructions in the pig knee. There is no intercondylar roof impingement after anatomical single bundle ACL reconstruction.

The 1991 version of the plume impingement computer program. Volume 2: User's input guide

NASA Technical Reports Server (NTRS)

Bender, Robert L.; Somers, Richard E.; Prendergast, Maurice J.; Clayton, Joseph P.; Smith, Sheldon D.

1991-01-01

The Plume Impingement Program (PLIMP) is a computer code used to predict impact pressures, forces, moments, heating rates, and contamination on surfaces due to direct impingement flowfields. Typically, it has been used to analyze the effects of rocket exhaust plumes on nearby structures from ground level to the vacuum of space. The program normally uses flowfields generated by the MOC, RAMP2, SPF/2, or SFPGEN computer programs. It is capable of analyzing gaseous and gas/particle flows. A number of simple subshapes are available to model the surfaces of any structure. The original PLIMP program has been modified many times of the last 20 years. The theoretical bases for the referenced major changes, and additional undocumented changes and enhancements since 1988 are summarized in volume 1 of this report. This volume is the User's Input Guide and should be substituted for all previous guides when running the latest version of the program. This version can operate on VAX and UNIX machines with NCAR graphics ability.

Vortex Ring Interaction with a Heated Screen

NASA Astrophysics Data System (ADS)

Smith, Jason; Krueger, Paul S.

2008-11-01

Previous examinations of vortex rings impinging on porous screens has shown the reformation of the vortex ring with a lower velocity after passing through the screen, the creation of secondary vortices, and mixing. A heated screen could, in principle, alter the vortex-screen interaction by changing the local liquid viscosity and density. In the present investigation, a mechanical piston-cylinder vortex ring generator was used to create vortex rings in an aqueous sucrose solution. The rings impinged on a screen of horizontal wires that were heated using electrical current. The flow was visualized with food color and video imaging. Tests with and without heat were conducted at a piston stroke-to-jet diameter ratio of 4 and a jet Reynolds number (Re) of 1000. The vortex rings slowed after passing through the screen, but in tests with heat, they maintained a higher fraction of their before-screen velocity due to reduction in fluid viscosity near the wires. In addition, small ``fingers'' that developed on the front of the vortex rings as they passed through the screen exhibited positive buoyancy effects in the heated case.

Closed circuit steam cooled turbine shroud and method for steam cooling turbine shroud

DOEpatents

Burdgick, Steven Sebastian; Sexton, Brendan Francis; Kellock, Iain Robertson

2002-01-01

A turbine shroud cooling cavity is partitioned to define a plurality of cooling chambers for sequentially receiving cooling steam and impingement cooling of the radially inner wall of the shoud. An impingement baffle is provided in each cooling chamber for receiving the cooling media from a cooling media inlet in the case of the first chamber or from the immediately upstream chamber in the case of the second through fourth chambers and includes a plurality of impingement holes for effecting the impingement cooling of the shroud inner wall.

Ankle impingement syndromes.

PubMed

Umans, Hilary

2002-06-01

The term "ankle impingement" encompasses a broad range of conditions that are typically post-traumatic and often chronic. Various forms of mechanical impingement can result from synovial proliferation, bone spur formation, or ligamentous scarring and hypertrophy. Since symptoms and physical findings can mimic a variety of disorders, accurate diagnosis may remain elusive, and proper effective therapy may be delayed. The objective of this article is to define and elucidate the etiology of the various forms of ankle impingement, clarify the range of associated osseous and soft-tissue pathology, and describe the imaging features and therapeutic options.

Mean flow characteristics for the oblique impingement of an axisymmetric jet

NASA Technical Reports Server (NTRS)

Foss, J. F.; Kleis, S. J.

1975-01-01

The oblique impingement of an axisymmetric jet has been investigated. A summary of the data and the analytical interpretations of the dominant mechanisms which influence the flow are reported. The major characteristics of the shallow angle oblique jet impingement flow field are: (1) minimal dynamic spreading as revealed by the surface pressure field, (2) pronounced kinematic spreading as revealed by the jet flow velocity field, (3) a pronounced upstream shift of the stagnation point from the maximum pressure point, (4) the production of streamwise vorticity by the impingement process.

Experimental and Computational Study of Underexpanded Jet Impingement Heat Transfer

NASA Technical Reports Server (NTRS)

Rufer, Shann J.; Nowak, Robert J.; Daryabeigi, Kamran; Picetti, Donald

2009-01-01

An experiment was performed to assess CFD modeling of a hypersonic-vehicle breach, boundary-layer flow ingestion and internal surface impingement. Tests were conducted in the NASA Langley Research Center 31-Inch Mach 10 Tunnel. Four simulated breaches were tested and impingement heat flux data was obtained for each case using both phosphor thermography and thin film gages on targets placed inside the model. A separate target was used to measure the surface pressure distribution. The measured jet impingement width and peak location are in good agreement with CFD analysis.

Normal Impingement of a Circular Liquid Jet onto a Screen in a Weightless Environment

NASA Technical Reports Server (NTRS)

Symons, E. P.

1976-01-01

The normal impingement of a circular liquid jet onto a fine-mesh screen in a weightless environment was investigated. Equations were developed to predict the velocity of the emerging jet on the downstream side of the screen as a function of screen and liquid parameters and of the velocity of the impinging jet. Additionally, the stability of the emerging jet was found to be Weber number dependent. In general, excepting at high velocities, the screen behaved much as a baffle, deflecting the major portion of the impinging flow.

Apparatus and methods for impingement cooling of a side wall of a turbine nozzle segment

DOEpatents

Burdgick, Steven Sebastian

2002-01-01

A gas turbine nozzle segment has outer and inner bands and a vane therebetween. Each band includes a nozzle wall, a side wall, a cover and an impingement plate between the cover and the nozzle wall defining two cavities on opposite sides of the impingement plate. Cooling steam is supplied to one cavity for flow through apertures of the impingement plate to cool the nozzle wall. The side wall of the band and inturned flange define with the nozzle wall an undercut region. The impingement plate has a turned flange welded to the inturned flange. A backing plate overlies the turned flange and aligned apertures are formed through the backing plate and turned flange to direct and focus cooling flow onto the side wall of the nozzle segment.

Sampling and detection of Legionella pneumophila aerosols generated from an industrial cooling tower.

PubMed

Ishimatsu, S; Miyamoto, H; Hori, H; Tanaka, I; Yoshida, S

2001-08-01

Cooling tower water has frequently been cited as a source of infection in outbreaks of Legionnaires' disease. However, there have been few reports on the presence of legionellae in aerosols from cooling towers. This paper describes our use of an impinger or a six-stage microbial impactor for detecting legionellae in air around a cooling tower contaminated with L. pneumophila (1.2+/-0.3x10(5) CFU/100 ml). Phosphate-buffered saline, Page's saline, 2% yeast extract solution and buffered yeast extract (BYE) broth were tested to evaluate their collection efficiency. These solutions were compared in laboratory experiments using an aerosol of L. pneumophila serogroup (SG) 1. Because BYE broth was the most efficient and storable collecting fluid among them, it was used for outdoor air sampling. In the outdoor air sampling, aerosolized L. pneumophila SG 6 was detected in the air around the cooling tower by the impinger (0.09 CFU/l. air). No legionellae were detected by the impactor with Legionella-selective agar plates (WYOalpha) because the plates were overgrown with fungi. Repetitive element PCR (rep-PCR) and arbitrarily primed PCR (AP-PCR) were employed to assess the epidemiological relationship among Legionella isolates from the air sample and the cooling tower water samples. L. pneumophila SG 6 isolated from the aerosols produced rep-PCR and AP-PCR fingerprints identical to those of L. pneumophila SG 6 strains from the cooling tower water, suggesting that the bacterium was aerosolized from the cooling tower.

Impinging laminar jets at moderate Reynolds numbers and separation distances.

PubMed

Bergthorson, Jeffrey M; Sone, Kazuo; Mattner, Trent W; Dimotakis, Paul E; Goodwin, David G; Meiron, Dan I

2005-12-01

An experimental and numerical study of impinging, incompressible, axisymmetric, laminar jets is described, where the jet axis of symmetry is aligned normal to the wall. Particle streak velocimetry (PSV) is used to measure axial velocities along the centerline of the flow field. The jet-nozzle pressure drop is measured simultaneously and determines the Bernoulli velocity. The flow field is simulated numerically by an axisymmetric Navier-Stokes spectral-element code, an axisymmetric potential-flow model, and an axisymmetric one-dimensional stream-function approximation. The axisymmetric viscous and potential-flow simulations include the nozzle in the solution domain, allowing nozzle-wall proximity effects to be investigated. Scaling the centerline axial velocity by the Bernoulli velocity collapses the experimental velocity profiles onto a single curve that is independent of the nozzle-to-plate separation distance. Axisymmetric direct numerical simulations yield good agreement with experiment and confirm the velocity profile scaling. Potential-flow simulations reproduce the collapse of the data; however, viscous effects result in disagreement with experiment. Axisymmetric one-dimensional stream-function simulations can predict the flow in the stagnation region if the boundary conditions are correctly specified. The scaled axial velocity profiles are well characterized by an error function with one Reynolds-number-dependent parameter. Rescaling the wall-normal distance by the boundary-layer displacement-thickness-corrected diameter yields a collapse of the data onto a single curve that is independent of the Reynolds number. These scalings allow the specification of an analytical expression for the velocity profile of an impinging laminar jet over the Reynolds number range investigated of .

Monte Carlo simulation of a near-continuum shock-shock interaction problem

NASA Technical Reports Server (NTRS)

Carlson, Ann B.; Wilmoth, Richard G.

1992-01-01

A complex shock interaction is calculated with direct simulation Monte Carlo (DSMC). The calculation is performed for the near-continuum flow produced when an incident shock impinges on the bow shock of a 0.1 in. radius cowl lip for freestream conditions of approximately Mach 15 and 35 km altitude. Solutions are presented both for a full finite-rate chemistry calculation and for a case with chemical reactions suppressed. In each case, both the undisturbed flow about the cowl lip and the full shock interaction flowfields are calculated. Good agreement has been obtained between the no-chemistry simulation of the undisturbed flow and a perfect gas solution obtained with the viscous shock-layer method. Large differences in calculated surface properties when different chemical models are used demonstrate the necessity of adequately representing the chemistry when making surface property predictions. Preliminary grid refinement studies make it possible to estimate the accuracy of the solutions.

Fission-Produced 99Mo Without a Nuclear Reactor.

PubMed

Youker, Amanda J; Chemerisov, Sergey D; Tkac, Peter; Kalensky, Michael; Heltemes, Thad A; Rotsch, David A; Vandegrift, George F; Krebs, John F; Makarashvili, Vakho; Stepinski, Dominique C

2017-03-01

99 Mo, the parent of the widely used medical isotope 99m Tc, is currently produced by irradiation of enriched uranium in nuclear reactors. The supply of this isotope is encumbered by the aging of these reactors and concerns about international transportation and nuclear proliferation. Methods: We report results for the production of 99 Mo from the accelerator-driven subcritical fission of an aqueous solution containing low enriched uranium. The predominately fast neutrons generated by impinging high-energy electrons onto a tantalum convertor are moderated to thermal energies to increase fission processes. The separation, recovery, and purification of 99 Mo were demonstrated using a recycled uranyl sulfate solution. Conclusion: The 99 Mo yield and purity were found to be unaffected by reuse of the previously irradiated and processed uranyl sulfate solution. Results from a 51.8-GBq 99 Mo production run are presented. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Analytical study of STOL Aircraft in ground effect. Part 1: Nonplanar, nonlinear wing/jet lifting surface method

NASA Technical Reports Server (NTRS)

Shollenberger, C. A.; Smyth, D. N.

1978-01-01

A nonlinear, nonplanar three dimensional jet flap analysis, applicable to the ground effect problem, is presented. Lifting surface methodology is developed for a wing with arbitrary planform operating in an inviscid and incompressible fluid. The classical, infintely thin jet flap model is employed to simulate power induced effects. An iterative solution procedure is applied within the analysis to successively approximate the jet shape until a converged solution is obtained which closely satisfies jet and wing boundary conditions. Solution characteristics of the method are discussed and example results are presented for unpowered, basic powered and complex powered configurations. Comparisons between predictions of the present method and experimental measurements indicate that the improvement of the jet with the ground plane is important in the analyses of powered lift systems operating in ground proximity. Further development of the method is suggested in the areas of improved solution convergence, more realistic modeling of jet impingement and calculation efficiency enhancements.

Thermal modulation voltammetry with laser heating at an aqueous|nitrobenzene solution microinterface: determination of the standard entropy changes of transfer for tetraalkylammonium ions.

PubMed

Hinoue, Teruo; Ikeda, Eiji; Watariguchi, Shigeru; Kibune, Yasuyuki

2007-01-01

Thermal modulation voltammetry (TMV) with laser heating was successfully performed at an aqueous|nitrobenzene (NB) solution microinterface, by taking advantage of the fact that laser light with a wavelength of 325.0 nm is optically transparent to the aqueous solution but opaque to the NB solution. When the laser beam impinges upon the interface from the aqueous solution side, a temperature is raised around the interface through the thermal diffusion subsequent to the light-to-heat conversion following the optical absorption by the NB solution near the interface. Based on such a principle, we achieved a fluctuating temperature perturbation around the interface for TMV by periodically irradiating the interface with the laser beam. On the other hand, the fluctuating temperature perturbation has influence on currents for transfer of an ion across the interface to produce fluctuating currents synchronized with the perturbation through temperature coefficients of several variables concerning the transfer, such as the standard transfer potential and the diffusion coefficient of the ion. Consequently, TMV has the possibility of providing information about the standard entropy change of transfer corresponding to a temperature coefficient of the standard transfer potential and a temperature coefficient of the diffusion coefficient. In this work, the aqueous|NB solution interface of 30 microm in diameter was irradiated with the laser beam at 10 Hz, and the currents synchronized with the periodical irradiation were recorded as a function of the potential difference across the interface in order to construct a TM voltammogram. TM voltammograms were measured for transfer of tetramethylammonium, tetraethylammonium, tetrapropylammonium, and tetra-n-butylammonium ions from the aqueous solution to the NB solution, and the standard entropy change of transfer was determined for each ion, according to an analytical procedure based on a mathematical expression of the TM voltammogram. Comparison of the values obtained in this work with the literature values has proved that TMV with laser heating is available for the determination of the standard entropy change of transfer for an ion.

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

Garlea, Elena; Steiner, M. A.; Calhoun, C. A.

The α-phase transformation kinetics of as-cast U - 8 wt% Mo below the eutectoid temperature have been established by in situ neutron diffraction. α-phase weight fraction data acquired through Rietveld refinement at five different isothermal hold temperatures can be modeled accurately utilizing a simple Johnson-Mehl-Avrami-Kolmogorov impingement-based theory, and the results are validated by a corresponding evolution in the γ-phase lattice parameter during transformation that follows Vegard’s law. Neutron diffraction data is used to produce a detailed Time-Temperature-Transformation diagram that improves upon inconsistencies in the current literature, exhibiting a minimum transformation start time of 40 min at temperatures between 500 °Cmore » and 510 °C. Lastly, the transformation kinetics of U – 8 wt% Mo can vary significantly from as-cast conditions after extensive heat treatments, due to homogenization of the typical dendritic microstructure which possesses non-negligible solute segregation.« less

Role of coherent structures in supersonic impinging jetsa)

NASA Astrophysics Data System (ADS)

Kumar, Rajan; Wiley, Alex; Venkatakrishnan, L.; Alvi, Farrukh

2013-07-01

This paper describes the results of a study examining the flow field and acoustic characteristics of a Mach 1.5 ideally expanded supersonic jet impinging on a flat surface and its control using steady microjets. Emphasis is placed on two conditions of nozzle to plate distances (h/d), of which one corresponds to where the microjet based active flow control is very effective in reducing flow unsteadiness and near-field acoustics and the other has minimal effectiveness. Measurements include unsteady pressures, nearfield acoustics using microphone and particle image velocimetry. The nearfield noise and unsteady pressure spectra at both h/d show discrete high amplitude impinging tones, which in one case (h/d = 4) are significantly reduced with control but in the other case (h/d = 4.5) remain unaffected. The particle image velocimetry measurements, both time-averaged and phase-averaged, were used to better understand the basic characteristics of the impinging jet flow field especially the role of coherent vortical structures in the noise generation and control. The results show that the flow field corresponding to the case of least control effectiveness comprise well defined, coherent, and symmetrical vortical structures and may require higher levels of microjet pressure supply for noise suppression when compared to the flow field more responsive to control (h/d = 4) which shows less organized, competing (symmetrical and helical) instabilities.

Simultaneous droplet impingement dynamics and heat transfer on nano-structured surfaces

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

Shen, Jian; Graber, Christof; Liburdy, James

This study examines the hydrodynamics and temperature characteristics of distilled deionized water droplets impinging on smooth and nano-structured surfaces using high speed (HS) and infrared (IR) imaging at We = 23.6 and Re = 1593, both based on initial drop impingement parameters. Results for a smooth and nano-structured surface for a range of surface temperatures are compared. Droplet impact velocity, transient spreading diameter and dynamic contact angle are measured. The near surface average droplet fluid temperatures are evaluated for conditions of evaporative cooling and boiling. Also included are surface temperature results using a gold layered IR opaque surface on silicon.more » Four stages of the impingement process are identified: impact, boiling, near constant surface diameter evaporation, and final dry-out. For the boiling conditions there is initial nucleation followed by severe boiling, then near constant diameter evaporation resulting in shrinking of the droplet height. When a critical contact angle is reached during evaporation the droplet rapidly retracts to a smaller diameter reducing the contact area with the surface. This continues as a sequence of retractions until final dry out. The basic trends are the same for all surfaces, but the nano-structured surface has a lower dissipated energy during impact and enhances the heat transfer for evaporative cooling with a 20% shorter time to achieve final dry out. (author)« less

Scapular Stabilization and Muscle Strength in Manual Wheelchair Users with Spinal Cord Injury and Subacromial Impingement.

PubMed

Wilbanks, Susan R; Bickel, C Scott

2016-01-01

Background: Manual wheelchair users with spinal cord injury (SCI) are frequently diagnosed with subacromial impingement. Objective: To determine whether the pattern of muscle imbalance and impaired scapular stabilization in able-bodied (AB) adults with impingement is different from that in manual wheelchair users with SCI and impingement. Methods: The following measurements were collected from 22 adults with subacromial impingement (11 SCI, 11 AB): ratio of normalized muscle electrical activity of upper and lower trapezius (UT:LT) during arm abduction; force during abduction, adduction, internal rotation, external rotation, and push and pull; ratios of force for abduction to adduction (AB:ADD), internal to external rotation (IR:ER), and push to pull (PUSH:PULL). Results: Shoulders with impingement had significantly higher UT:LT activation (1.46 ± 0.52) than shoulders without impingement (0.93 ± 0.45) ( P = .006), regardless of wheelchair user status. Significant differences between AB participants and those with SCI were observed for ABD:ADD ( P = .005), PUSH:PULL ( P = .012), and pull strength ( P = .043). Participants with SCI had a significantly greater ABD:ADD (1.37 ± 0.36) than AB participants (1.04 ± 0.22) ( P = .002) and a significantly greater PUSH:PULL (1.53 ± 0.36) than AB participants (1.26 ± 0.18) ( P = .005) because of decreased strength in adduction ( P = .021) and pull ( P = .013). Conclusions: Strategies targeting the posterior shoulder girdle for AB adults are appropriate for manual wheelchair users with SCI and impingement and should focus on scapular retractors and arm adductors with emphasis on scapular depression and posterior tilting.

Visualization of high speed liquid jet impaction on a moving surface.

PubMed

Guo, Yuchen; Green, Sheldon

2015-04-17

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds between 0 and 25 m/sec) and a spinning disk device (for examining surface speeds between 15 and 100 m/sec). The air cannon linear traverse is a pneumatic energy-powered system that is designed to accelerate a metal rail surface mounted on top of a wooden projectile. A pressurized cylinder fitted with a solenoid valve rapidly releases pressurized air into the barrel, forcing the projectile down the cannon barrel. The projectile travels beneath a spray nozzle, which impinges a liquid jet onto its metal upper surface, and the projectile then hits a stopping mechanism. A camera records the jet impingement, and a pressure transducer records the spray nozzle backpressure. The spinning disk set-up consists of a steel disk that reaches speeds of 500 to 3,000 rpm via a variable frequency drive (VFD) motor. A spray system similar to that of the air cannon generates a liquid jet that impinges onto the spinning disc, and cameras placed at several optical access points record the jet impingement. Video recordings of jet impingement processes are recorded and examined to determine whether the outcome of impingement is splash, splatter, or deposition. The apparatuses are the first that involve the high speed impingement of low-Reynolds-number liquid jets on high speed moving surfaces. In addition to its rail industry applications, the described technique may be used for technical and industrial purposes such as steelmaking and may be relevant to high-speed 3D printing.

Visualization of High Speed Liquid Jet Impaction on a Moving Surface

PubMed Central

Guo, Yuchen; Green, Sheldon

2015-01-01

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds between 0 and 25 m/sec) and a spinning disk device (for examining surface speeds between 15 and 100 m/sec). The air cannon linear traverse is a pneumatic energy-powered system that is designed to accelerate a metal rail surface mounted on top of a wooden projectile. A pressurized cylinder fitted with a solenoid valve rapidly releases pressurized air into the barrel, forcing the projectile down the cannon barrel. The projectile travels beneath a spray nozzle, which impinges a liquid jet onto its metal upper surface, and the projectile then hits a stopping mechanism. A camera records the jet impingement, and a pressure transducer records the spray nozzle backpressure. The spinning disk set-up consists of a steel disk that reaches speeds of 500 to 3,000 rpm via a variable frequency drive (VFD) motor. A spray system similar to that of the air cannon generates a liquid jet that impinges onto the spinning disc, and cameras placed at several optical access points record the jet impingement. Video recordings of jet impingement processes are recorded and examined to determine whether the outcome of impingement is splash, splatter, or deposition. The apparatuses are the first that involve the high speed impingement of low-Reynolds-number liquid jets on high speed moving surfaces. In addition to its rail industry applications, the described technique may be used for technical and industrial purposes such as steelmaking and may be relevant to high-speed 3D printing. PMID:25938331

Anterior ankle impingement syndromes.

PubMed

Umans, Hilary R; Cerezal, Luiz

2008-06-01

Ankle impingement syndromes are painful conditions that may complicate ankle trauma and are characterized by chronic, progressive pain, swelling, and limitation of movement. These disorders are subclassified according to anatomical location about the tibiotalar joint. This article reviews the various forms of anterior ankle impingement, detailing the unique clinical features, anatomical considerations, pathoetiology, and imaging findings for each.

Occult hemoglobin as an indicator of impingement stress in fishes

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

Not Available

1980-01-01

During the process of impingement on cooling system intake screens, fish may be subject to different types of stress, the total of which often results in the death of individual fish. This report assesses the use of occult hemoglobin in fish demand mucus as an indicator of impingement stress. (ACR)

Physics of Particle Entrainment Under the Influence of an Impinging Jet

DTIC Science & Technology

2008-12-01

Approved for public release; distribution unlimited 1 PHYSICS OF PARTICLE ENTRAINMENT UNDER THE INFLUENCE OF AN IMPINGING JET Robert Haehnel...Ing. Wesen. Heft 361). Phares, D.J., Smedley , G.T. and Flagan, R.C. (2000) "The wall shear stress produced by the normal impingement of a jet on a

Atomization of Impinging Droplets on Superheated Superhydrophobic Surfaces

NASA Astrophysics Data System (ADS)

Emerson, Preston; Crockett, Julie; Maynes, Daniel

2017-11-01

Water droplets impinging smooth superheated surfaces may be characterized by dynamic vapor bubbles rising to the surface, popping, and causing a spray of tiny droplets to erupt from the droplet. This spray is called secondary atomization. Here, atomization is quantified experimentally for water droplets impinging superheated superhydrophobic surfaces. Smooth hydrophobic and superhydrophobic surfaces with varying rib and post microstructuring were explored. Each surface was placed on an aluminum heating block, and impingement events were captured with a high speed camera at 3000 fps. For consistency among tests, all events were normalized by the maximum atomization found over a range of temperatures on a smooth hydrophobic surface. An estimate of the level of atomization during an impingement event was created by quantifying the volume of fluid present in the atomization spray. Droplet diameter and Weber number were held constant, and atomization was found for a range of temperatures through the lifetime of the impinging droplet. The Leidenfrost temperature was also determined and defined to be the lowest temperature at which atomization ceases to occur. Both atomization and Leidenfrost temperature increase with decreasing pitch (distance between microstructures).

Noise of the Harrier in vertical landing and takeoff

NASA Technical Reports Server (NTRS)

Soderman, Paul T.; Foster, John D.

1988-01-01

The noise of the Harrier AV8C aircraft in vertical takeoff and landing was measured 100 feet to the side of the aircraft where jet noise dominates. The noise levels were quite high - up to 125 dB overall sound level at 100 feet. The increased noise due to jet impingement on the ground is presented as a function of jet height to diameter ratio. The impingement noise with the aircraft close to the ground was 14 to 17 dB greater than noise from a free jet. Results are compared with small-scale jet impingement data acquired elsewhere. The agreement between small-scale and full-scale noise increase in ground effect is fairly good except with the jet close to the ground. It is proposed that differences in the jet Reynolds numbers and the resultant character of the jets may be partially responsible for the disparity in the full-scale and small-scale jet impingement noise. The difference between single-jet impingement and multiple-jet impingement may also have been responsible for the small-scale and full-scale disagreement.

Comparison of Fourier transform infrared spectrometry and 2,4-dinitrophenylhydrazine impinger techniques for the measurement of formaldehyde in vehicle exhaust

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

Haack, L.P.; LaCourse, D.L.; Korniski, T.J.

1986-01-01

Experiments were conducted to validate a Fourier transform infrared (FT-IR) sampling and analysis system for measurement of trace gases in vehicle exhaust utilizing gasoline-, gasohol-, diesel-, and methanol-fueled vehicles as the emission source and formaldehyde (HCHO) as the test molecule. The 2,4-dinitrophenylhydrazine impinger method was chosen as the reference method. Diluted exhaust was drawn continuously though the FT-IR cell and measured every 3 s. The FT-IR signals were averaged over a complete driving-test cycle and compared to the concentration determined from concurrent impinger sampling. By impinger measurements it was shown that HCHO losses between the tailpipe and the FT-IR cellmore » were on the order of only 5%, independent of vehicle type or HCHO concentration (0.02-8.5 ppm). Comparisons between FT-IR and impinger measurements on 43 tests of methanol-fueled vehicles under transient conditions (diluted-exhaust HCHO 0.28-8.5 ppm) showed FT-IR/impinger = 1.055 +/- 0.095. 19 references, 5 figures, 5 tables.« less

Spray formation processes of impinging jet injectors

NASA Technical Reports Server (NTRS)

Anderson, W. E.; Ryan, H. M.; Pal, S.; Santoro, R. J.

1993-01-01

A study examining impinging liquid jets has been underway to determine physical mechanisms responsible for combustion instabilities in liquid bi-propellant rocket engines. Primary atomization has been identified as an important process. Measurements of atomization length, wave structure, and drop size and velocity distribution were made under various ambient conditions. Test parameters included geometric effects and flow effects. It was observed that pre-impingement jet conditions, specifically whether they were laminar or turbulent, had the major effect on primary atomization. Comparison of the measurements with results from a two dimensional linear aerodynamic stability model of a thinning, viscous sheet were made. Measured turbulent impinging jet characteristics were contrary to model predictions; the structure of waves generated near the point of jet impingement were dependent primarily on jet diameter and independent of jet velocity. It has been postulated that these impact waves are related to pressure and momentum fluctuations near the impingement region and control the eventual disintegration of the liquid sheet into ligaments. Examination of the temporal characteristics of primary atomization (ligament shedding frequency) strongly suggests that the periodic nature of primary atomization is a key process in combustion instability.

The effect of dynamic femoroacetabular impingement on pubic symphysis motion: a cadaveric study.

PubMed

Birmingham, Patrick M; Kelly, Bryan T; Jacobs, Robert; McGrady, Linda; Wang, Mei

2012-05-01

A link between femoroacetabular impingement and athletic pubalgia has been reported clinically. One proposed origin of athletic pubalgia is secondary to repetitive loading of the pubic symphysis, leading to instability and parasymphyseal tendon and ligament injury. Hypothesis/ The purpose of this study was to investigate the effect of simulated femoral-based femoroacetabular impingement on rotational motion at the pubic symphysis. The authors hypothesize that the presence of a cam lesion leads to increased relative symphyseal motion. Controlled laboratory study. Twelve hips from 6 fresh-frozen human cadaveric pelvises were used to simulate cam-type femoroacetabular impingement. The hips were held in a custom jig and maximally internally rotated at 90° of flexion and neutral adduction. Three-dimensional motion of the pubic symphysis was measured by a motion-tracking system for 2 states: native and simulated cam. Load-displacement plots were generated between the internal rotational torque applied to the hip and the responding motion in 3 anatomic planes of the pubic symphysis. As the hip was internally rotated, the motion at the pubic symphysis increased proportionally with the degrees of the rotation as well as the applied torque measured at the distal femur for both states. The primary rotation of the symphysis was in the transverse plane and on average accounted for more than 60% of the total rotation. This primary motion caused the anterior aspect of the symphyseal joint to open or widen, whereas the posterior aspect narrowed. At the torque level of 18.0 N·m, the mean transverse rotation in degrees was 0.89° ± 0.35° for the native state and 1.20° ± 0.41° for cam state. The difference between cam and the native groups was statistically significant (P < .03). Dynamic femoroacetabular impingement as caused by the presence of a cam lesion causes increased rotational motion at the pubic symphysis. Repetitive loading of the symphysis by cam impingement is thought to lead to increased symphyseal motion, which is one possible precursor to athletic pubalgia.

Impinging jet separators for liquid metal magnetohydrodynamic power cycles

NASA Technical Reports Server (NTRS)

Bogdanoff, D. W.

1973-01-01

In many liquid metal MHD power, cycles, it is necessary to separate the phases of a high-speed liquid-gas flow. The usual method is to impinge the jet at a glancing angle against a solid surface. These surface separators achieve good separation of the two phases at a cost of a large velocity loss due to friction at the separator surface. This report deals with attempts to greatly reduce the friction loss by impinging two jets against each other. In the crude impinging jet separators tested to date, friction losses were greatly reduced, but the separation of the two phases was found to be much poorer than that achievable with surface separators. Analyses are presented which show many lines of attack (mainly changes in separator geometry) which should yield much better separation for impinging jet separators).

Ultrasound of the coracoacromial ligament in asymptomatic volunteers and patients with shoulder impingement.

PubMed

Dietrich, Tobias J; Jonczy, Maciej; Buck, Florian M; Sutter, Reto; Puskas, Gabor J; Pfirrmann, Christian Wa

2016-08-01

The coracoacromial ligament is part of the coracoacromial arch, which is considered to be involved in shoulder impingement. To compare the coracoacromial ligament on ultrasound in asymptomatic volunteers and in patients with subacromial shoulder impingement. Twenty-nine asymptomatic volunteers (mean age, 35.5 years) and 29 patients (mean age, 49.9 years) with shoulder impingement, diagnosed by experienced shoulder surgeons, were prospectively included. Two radiologists obtained and analyzed ultrasound images of the coracoacromial ligament in the longitudinal axis. The ligament thickness was 1.4 ± 0.2 mm at its midportion, 1.8 ± 0.4 mm at the coracoid, and 2.1 ± 0.6 mm at the acromion in asymptomatic volunteers compared with 1.3 ± 0.2 mm, 1.9 ± 0.5 mm, and 1.9 ± 0.5 mm in impingement patients for observer 1. The ligament length was 30.6 ± 2.4 mm in asymptomatic volunteers compared with 30.4 ± 3.6 mm in impingement patients for observer 1. An anteriorly convex shape of the superficial contour of the coracoacromial ligament was significantly more frequent in impingement patients compared with asymptomatic volunteers for both observers (observer 1: 10% (3/29) versus 45% (13/29), P value <0.01; observer 2: 10% (3/29) versus 38% (11/29), P value <0.03). The comparison of the remaining parameters of the coracoacromial ligament, such as the thickness, length, echogenicity, and fibrillation did not reveal significant differences between volunteers and patients. While thickness or length of the coracoacromial ligament were similar in volunteers and patients with shoulder impingement, an anteriorly convex shape of the superficial contour of the coracoacromial ligament was significantly more frequent in impingement patients compared with asymptomatic volunteers. © The Foundation Acta Radiologica 2015.

Shuttle interaction study extension

NASA Technical Reports Server (NTRS)

1982-01-01

The following areas of Space Shuttle technology were discussed: variable altitude strategy, spacecraft servicing, propellant storage, orbiter plume impingement, space based design, mating (docking and berthing), shuttle fleet utilization, and mission/traffic model.

Making a case for anterior inferior iliac spine/subspine hip impingement: three representative case reports and proposed concept.

PubMed

Larson, Christopher M; Kelly, Bryan T; Stone, Rebecca M

2011-12-01

Femoroacetabular impingement is typically described as occurring due to a conflict between the femoral head-neck junction and acetabular rim. A prior case report described an open decompression of the anterior inferior iliac spine (AIIS) due to impingement against the proximal femur. AIIS impingement may be developmental or the result of a prior AIIS avulsion or pelvic osteotomy. We describe 3 representative cases with minimum 1-year follow-up treated with an arthroscopic AIIS decompression. Copyright © 2011 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Slurry Erosion Performance of Ni-Al2O3 Based Thermal-Sprayed Coatings: Effect of Angle of Impingement

NASA Astrophysics Data System (ADS)

Grewal, H. S.; Agrawal, Anupam; Singh, H.; Shollock, B. A.

2014-02-01

In this paper, slurry erosion performance of high velocity flame-sprayed Ni-Al2O3 based coatings was evaluated. The coatings were deposited on a hydroturbine steel (CA6NM) by varying the content of Al2O3 in Ni. Using jet-type test rig, erosion behavior of coatings and bare steel was evaluated at different impingement angles. Detailed investigation of the surface morphology of the eroded specimens was undertaken using SEM/EDS to identify potential erosion mechanism. A parameter named "erosion mechanism identifier" (ξ) was used to predict the mode of erosion. It was observed that the coating prepared using 40 wt.% of Al2O3 showed a highest resistance to erosion. This coating enhanced the erosion resistance of the steel by 2 to 4 times. Spalling in the form of splats and chunks of material (formed by interlinking of cracks) along with fracture of Al2O3 splats were identified as primary mechanisms responsible for the loss of coating material. The erosion mechanism of coatings and bare steel predicted by ξ was in good agreement with that observed experimentally. Among different parameters,, a function of fracture toughness ( K IC) and hardness ( H) showed excellent correlation with erosion resistance of coatings at both the impingement angles.

Modeling of turbulent separated flows for aerodynamic applications

NASA Technical Reports Server (NTRS)

Marvin, J. G.

1983-01-01

Steady, high speed, compressible separated flows modeled through numerical simulations resulting from solutions of the mass-averaged Navier-Stokes equations are reviewed. Emphasis is placed on benchmark flows that represent simplified (but realistic) aerodynamic phenomena. These include impinging shock waves, compression corners, glancing shock waves, trailing edge regions, and supersonic high angle of attack flows. A critical assessment of modeling capabilities is provided by comparing the numerical simulations with experiment. The importance of combining experiment, numerical algorithm, grid, and turbulence model to effectively develop this potentially powerful simulation technique is stressed.

New singlet oxygen generator for chemical oxygen-iodine lasers

NASA Astrophysics Data System (ADS)

Yoshida, S.; Saito, H.; Fujioka, T.; Yamakoshi, H.; Uchiyama, T.

1986-11-01

Experiments have been carried out to investigate a new method for generating O2(1Delta) with long-time operation of an efficient chemical oxygen-iodine laser system in mind. An impinging-jet nozzle was utilized to atomize a H2O2-KOH solution so that the alkaline H2O2/Cl2 reaction might occur in droplet-gas phase with high excitation efficiency. Experimental results indicate that the present generator can yield as high as 80 percent of O2(1Delta) with reasonable O2 flow rate.

Numerical solution for the temperature distribution in a cooled guide vane blade of a radial gas turbine

NASA Technical Reports Server (NTRS)

Hosny, W. M.; Tabakoff, W.

1977-01-01

A two dimensional finite difference numerical technique is presented to determine the temperature distribution of an internal cooled blade of radial turbine guide vanes. A simple convection cooling is assumed inside the guide vane blade. Such cooling has relatively small cooling effectiveness at the leading edge and at the trailing edge. Heat transfer augmentation in these critical areas may be achieved by using impingement jets and film cooling. A computer program is written in FORTRAN IV for IBM 370/165 computer.

Lubricant Jet Flow Phenomena in Spur and Helical Gears with Modified Addendums; for Radially Directed Individual Jets

NASA Technical Reports Server (NTRS)

Akin, Lee S.; Townsend, Dennis P.

1989-01-01

This paper develops the mathematical relations for the Virtual Kinetic Model as an improvement over the vectorial model developed earlier. The model solution described provides the most energy efficient means of cooling gears, i.e., it requires the least pressure or pumping power to distribute the coolant onto the tooth surface. Further, this nozzle orientation allows impingement to the root of the tooth if needed and provides the most cooling control when compared to into-mesh and out-of-mesh cooling.

Lubricant jet flow phenomena in spur and helical gears with modified addendums - For radially directed individual jets

NASA Technical Reports Server (NTRS)

Akin, L. S.; Townsend, D. P.

1989-01-01

This paper develops the mathematical relations for the Virtual Kinetic Model as an improvement over the vectorial model developed earlier. The model solution described provides the most energy efficient means of cooling gears, i.e., it requires the least pressure or pumping power to distribute the coolant onto the tooth surface. Further, this nozzle orientation allows impingement to the root of the tooth if needed and provides the most cooling control when compared to into-mesh and out-of-mesh cooling.

Interactive orbital proximity operations planning system instruction and training guide

NASA Technical Reports Server (NTRS)

Grunwald, Arthur J.; Ellis, Stephen R.

1994-01-01

This guide instructs users in the operation of a Proximity Operations Planning System. This system uses an interactive graphical method for planning fuel-efficient rendezvous trajectories in the multi-spacecraft environment of the space station and allows the operator to compose a multi-burn transfer trajectory between orbit initial chaser and target trajectories. The available task time (window) of the mission is predetermined and the maneuver is subject to various operational constraints, such as departure, arrival, spatial, plume impingement, and en route passage constraints. The maneuvers are described in terms of the relative motion experienced in a space station centered coordinate system. Both in-orbital plane as well as out-of-orbital plane maneuvering is considered. A number of visual optimization aids are used for assisting the operator in reaching fuel-efficient solutions. These optimization aids are based on the Primer Vector theory. The visual feedback of trajectory shapes, operational constraints, and optimization functions, provided by user-transparent and continuously active background computations, allows the operator to make fast, iterative design changes that rapidly converge to fuel-efficient solutions. The planning tool is an example of operator-assisted optimization of nonlinear cost functions.

Mapping of local argon impingement on a virtual surface: an insight for gas injection during FEBID

NASA Astrophysics Data System (ADS)

Wanzenboeck, H. D.; Hochleitner, G.; Mika, J.; Shawrav, M. M.; Gavagnin, M.; Bertagnolli, E.

2014-12-01

During the last decades, focused electron beam induced deposition (FEBID) has become a successful approach for direct-write fabrication of nanodevices. Such a deposition technique relies on the precursor supply to the sample surface which is typically accomplished by a gas injection system using a tube-shaped injector nozzle. This precursor injection strategy implies a position-dependent concentration gradient on the surface, which affects the geometry and chemistry of the final nanodeposit. Although simulations already proposed the local distribution of nozzle-borne gas molecules impinging on the surface, this isolated step in the FEBID process has never been experimentally measured yet. This work experimentally investigates the local distribution of impinging gas molecules on the sample plane, isolating the direct impingement component from surface diffusion or precursor depletion by deposition. The experimental setup used in this work maps and quantifies the local impinging rate of argon gas over the sample plane. This setup simulates the identical conditions for a precursor molecule during FEBID. Argon gas was locally collected with a sniffer tube, which is directly connected to a residual gas analyzer for quantification. The measured distribution of impinging gas molecules showed a strong position dependence. Indeed, a 300-µm shift of the deposition area to a position further away from the impingement center spot resulted in a 50 % decrease in the precursor impinging rate on the surface area. With the same parameters, the precursor distribution was also simulated by a Monte Carlo software by Friedli and Utke and showed a good correlation between the empirical and the simulated precursor distribution. The results hereby presented underline the importance of controlling the local precursor flux conditions in order to obtain reproducible and comparable deposition results in FEBID.

Traction Drive Inverter Cooling with Submerged Liquid Jet Impingement on Microfinned Enhanced Surfaces (Presentation)

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

Waye, S.; Narumanchi, S.; Moreno, G.

Jet impingement is one means to improve thermal management for power electronics in electric-drive traction vehicles. Jet impingement on microfin-enhanced surfaces further augments heat transfer and thermal performance. A channel flow heat exchanger from a commercial inverter was characterized as a baseline system for comparison with two new prototype designs using liquid jet impingement on plain and microfinned enhanced surfaces. The submerged jets can target areas with the highest heat flux to provide local cooling, such as areas under insulated-gate bipolar transistors and diode devices. Low power experiments, where four diodes were powered, dissipated 105 W of heat and weremore » used to validate computational fluid dynamics modeling of the baseline and prototype designs. Experiments and modeling used typical automotive flow rates using water-ethylene glycol as a coolant (50%-50% by volume). The computational fluid dynamics model was used to predict full inverter power heat dissipation. The channel flow and jet impingement configurations were tested at full inverter power of 40 to 100 kW (output power) on a dynamometer, translating to an approximate heat dissipation of 1 to 2 kW. With jet impingement, the cold plate material is not critical for the thermal pathway. A high-temperature plastic was used that could eventually be injection molded or formed, with the jets formed from a basic aluminum plate with orifices acting as nozzles. Long-term reliability of the jet nozzles and impingement on enhanced surfaces was examined. For jet impingement on microfinned surfaces, thermal performance increased 17%. Along with a weight reduction of approximately 3 kg, the specific power (kW/kg) increased by 36%, with an increase in power density (kW/L) of 12% compared with the baseline channel flow configuration.« less

The Effect of Reaction Control System Thruster Plume Impingement on Orion Service Module Solar Array Power Production

NASA Technical Reports Server (NTRS)

Bury, Kristen M.; Kerslake, Thomas W.

2008-01-01

NASA's new Orion Crew Exploration Vehicle has geometry that orients the reaction control system (RCS) thrusters such that they can impinge upon the surface of Orion's solar array wings (SAW). Plume impingement can cause Paschen discharge, chemical contamination, thermal loading, erosion, and force loading on the SAW surface, especially when the SAWs are in a worst-case orientation (pointed 45 towards the aft end of the vehicle). Preliminary plume impingement assessment methods were needed to determine whether in-depth, timeconsuming calculations were required to assess power loss. Simple methods for assessing power loss as a result of these anomalies were developed to determine whether plume impingement induced power losses were below the assumed contamination loss budget of 2 percent. This paper details the methods that were developed and applies them to Orion's worst-case orientation.

Cap assembly for a bundled tube fuel injector

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

LeBegue, Jeffrey Scott; Melton, Patrick Benedict; Westmoreland, III, James Harold

2016-04-26

A cap assembly for a bundled tube fuel injector includes an impingement plate and an aft plate that is disposed downstream from the impingement plate. The aft plate includes a forward side that is axially separated from an aft side. A tube passage extends through the impingement plate and the aft plate. A tube sleeve extends through the impingement plate within the tube passage towards the aft plate. The tube sleeve includes a flange at a forward end and an aft end that is axially separated from the forward end. A retention plate is positioned upstream from the impingement plate.more » A spring is disposed between the retention plate and the flange. The spring provides a force so as to maintain contact between at least a portion of the aft end of the tube sleeve and the forward side of the aft plate.« less

Hip impingement: identifying and treating a common cause of hip pain.

PubMed

Kuhlman, Geoffrey S; Domb, Benjamin G

2009-12-15

Femoroacetabular impingement, also known as hip impingement, is the abutment of the acetabular rim and the proximal femur. Hip impingement is increasingly recognized as a common etiology of hip pain in athletes, adolescents, and adults. It injures the labrum and articular cartilage, and can lead to osteoarthritis of the hip if left untreated. Patients with hip impingement often report anterolateral hip pain. Common aggravating activities include prolonged sitting, leaning forward, getting in or out of a car, and pivoting in sports. The use of flexion, adduction, and internal rotation of the supine hip typically reproduces the pain. Radiography, magnetic resonance arthrography, and injection of local anesthetic into the hip joint confirm the diagnosis. Pain may improve with physical therapy. Treatment often requires arthroscopy, which typically allows patients to resume premorbid physical activities. An important goal of arthroscopy is preservation of the hip joint. Whether arthroscopic treatment prevents or delays osteoarthritis of the hip is unknown.

Two stage serial impingement cooling for isogrid structures

DOEpatents

Lee, Ching-Pang; Morrison, Jay A.

2014-09-09

A system for cooling a wall (24) of a component having an outer surface with raised ribs (12) defining a structural pocket (10), including: an inner wall (26) within the structural pocket and separating the wall outer surface within the pocket into a first region (28) outside of the inner wall and a second region (40) enclosed by the inner wall; a plate (14) disposed atop the raised ribs and enclosing the structural pocket, the plate having a plate impingement hole (16) to direct cooling air onto an impingement cooled area (38) of the first region; a cap having a skirt (50) in contact with the inner wall, the cap having a cap impingement hole (20) configured to direct the cooling air onto an impingement cooled area (44) of the second region, and; a film cooling hole (22) formed through the wall in the second region.

The Effect of Reaction Control System Thruster Plume Impingement on Orion Service Module Solar Array Power Production

NASA Astrophysics Data System (ADS)

Bury, Kristen M.; Kerslake, Thomas W.

2008-06-01

NASA's new Orion Crew Exploration Vehicle has geometry that orients the reaction control system (RCS) thrusters such that they can impinge upon the surface of Orion's solar array wings (SAW). Plume impingement can cause Paschen discharge, chemical contamination, thermal loading, erosion, and force loading on the SAW surface, especially when the SAWs are in a worst-case orientation (pointed 45 towards the aft end of the vehicle). Preliminary plume impingement assessment methods were needed to determine whether in-depth, timeconsuming calculations were required to assess power loss. Simple methods for assessing power loss as a result of these anomalies were developed to determine whether plume impingement induced power losses were below the assumed contamination loss budget of 2 percent. This paper details the methods that were developed and applies them to Orion's worst-case orientation.

Physical tests for shoulder impingements and local lesions of bursa, tendon or labrum that may accompany impingement.

PubMed

Hanchard, Nigel C A; Lenza, Mário; Handoll, Helen H G; Takwoingi, Yemisi

2013-04-30

Impingement is a common cause of shoulder pain. Impingement mechanisms may occur subacromially (under the coraco-acromial arch) or internally (within the shoulder joint), and a number of secondary pathologies may be associated. These include subacromial-subdeltoid bursitis (inflammation of the subacromial portion of the bursa, the subdeltoid portion, or both), tendinopathy or tears affecting the rotator cuff or the long head of biceps tendon, and glenoid labral damage. Accurate diagnosis based on physical tests would facilitate early optimisation of the clinical management approach. Most people with shoulder pain are diagnosed and managed in the primary care setting. To evaluate the diagnostic accuracy of physical tests for shoulder impingements (subacromial or internal) or local lesions of bursa, rotator cuff or labrum that may accompany impingement, in people whose symptoms and/or history suggest any of these disorders. We searched electronic databases for primary studies in two stages. In the first stage, we searched MEDLINE, EMBASE, CINAHL, AMED and DARE (all from inception to November 2005). In the second stage, we searched MEDLINE, EMBASE and AMED (2005 to 15 February 2010). Searches were delimited to articles written in English. We considered for inclusion diagnostic test accuracy studies that directly compared the accuracy of one or more physical index tests for shoulder impingement against a reference test in any clinical setting. We considered diagnostic test accuracy studies with cross-sectional or cohort designs (retrospective or prospective), case-control studies and randomised controlled trials. Two pairs of review authors independently performed study selection, assessed the study quality using QUADAS, and extracted data onto a purpose-designed form, noting patient characteristics (including care setting), study design, index tests and reference standard, and the diagnostic 2 x 2 table. We presented information on sensitivities and specificities with 95% confidence intervals (95% CI) for the index tests. Meta-analysis was not performed. We included 33 studies involving 4002 shoulders in 3852 patients. Although 28 studies were prospective, study quality was still generally poor. Mainly reflecting the use of surgery as a reference test in most studies, all but two studies were judged as not meeting the criteria for having a representative spectrum of patients. However, even these two studies only partly recruited from primary care.The target conditions assessed in the 33 studies were grouped under five main categories: subacromial or internal impingement, rotator cuff tendinopathy or tears, long head of biceps tendinopathy or tears, glenoid labral lesions and multiple undifferentiated target conditions. The majority of studies used arthroscopic surgery as the reference standard. Eight studies utilised reference standards which were potentially applicable to primary care (local anaesthesia, one study; ultrasound, three studies) or the hospital outpatient setting (magnetic resonance imaging, four studies). One study used a variety of reference standards, some applicable to primary care or the hospital outpatient setting. In two of these studies the reference standard used was acceptable for identifying the target condition, but in six it was only partially so. The studies evaluated numerous standard, modified, or combination index tests and 14 novel index tests. There were 170 target condition/index test combinations, but only six instances of any index test being performed and interpreted similarly in two studies. Only two studies of a modified empty can test for full thickness tear of the rotator cuff, and two studies of a modified anterior slide test for type II superior labrum anterior to posterior (SLAP) lesions, were clinically homogenous. Due to the limited number of studies, meta-analyses were considered inappropriate. Sensitivity and specificity estimates from each study are presented on forest plots for the 170 target condition/index test combinations grouped according to target condition. There is insufficient evidence upon which to base selection of physical tests for shoulder impingements, and local lesions of bursa, tendon or labrum that may accompany impingement, in primary care. The large body of literature revealed extreme diversity in the performance and interpretation of tests, which hinders synthesis of the evidence and/or clinical applicability.

Apparatus and methods for impingement cooling of an undercut region adjacent a side wall of a turbine nozzle segment

DOEpatents

Burdgick, Steven Sebastian; Itzel, Gary Michael

2001-01-01

A gas turbine nozzle segment has outer and inner bands. Each band includes a side wall, a cover and an impingement plate between the cover and nozzle wall defining two cavities on opposite sides of the impingement plate. Cooling steam is supplied to one cavity for flow through apertures of the impingement plate to cool the nozzle wall. The side wall of the band and inturned flange define with the nozzle wall an undercut region. The inturned flange has a plurality of apertures for directing cooling steam to cool the side wall between adjacent nozzle segments.

The Effect of Impingement on Transitional Behavior in Underexpanded Jets

NASA Technical Reports Server (NTRS)

Inman, Jennifer A.; Danehy, Paul M.; Nowak, Robert J.; Alderfer, David W.

2009-01-01

An investigation into the development of flow unsteadiness in impinging axisymmetric underexpanded jets has been conducted at NASA Langley Research Center. The study has examined the effect of an impingement target placed at various distances and angles on transitional behavior of such jets. Two nozzles, with exit Mach numbers of 1.0 and 2.6, were used in this investigation. Planar laser-induced fluorescence of nitric oxide (NO PLIF) has been used to identify flow unsteadiness and to image transitional and turbulent flow features. Measurements of the location of the onset of various degrees of unsteady flow behavior have been made using these PLIF images. Both qualitative and quantitative comparisons are presented to demonstrate the observed effects of impingement and flow parameters on the process of the transition to turbulence. The presence of the impingement target was found to significantly shorten the distance to transition to turbulence by up to a factor of approximately three, with closer targets resulting in slightly shorter distance to transition and turbulence. The location at which the flow first exhibits unsteadiness was found to have a strong dependence on the presence and location of key flow structures. This paper presents quantitative results on transition criteria for free and impinging jets.

The Existence of Steady Compressible Subsonic Impinging Jet Flows

NASA Astrophysics Data System (ADS)

Cheng, Jianfeng; Du, Lili; Wang, Yongfu

2018-03-01

In this paper, we investigate the compressible subsonic impinging jet flows through a semi-infinitely long nozzle and impacting on a solid wall. Firstly, it is shown that given a two-dimensional semi-infinitely long nozzle and a wall behind the nozzle, and an appropriate atmospheric pressure, then there exists a smooth global subsonic compressible impinging jet flow with two asymptotic directions. The subsonic impinging jet develops two free streamlines, which initiate smoothly at the end points of the semi-infinitely long nozzles. In particular, there exists a smooth curve which separates the fluids which go to different places downstream. Moreover, under some suitable asymptotic assumptions of the nozzle, the asymptotic behaviors of the compressible subsonic impinging jet flows in the inlet and the downstream are obtained by means of a blow-up argument. On the other hand, the non-existence of compressible subsonic impinging jet flows with only one asymptotic direction is also established. This main result in this paper solves the open problem (4) in Chapter 16.3 proposed by uc(Friedman) in his famous survey (uc(Friedman) in Mathematics in industrial problems, II, I.M.A. volumes in mathematics and its applications, vol 24, Springer, New York, 1989).

Experimental and numerical investigation of liquid jet impingement on superhydrophobic and hydrophobic convex surfaces

NASA Astrophysics Data System (ADS)

Kibar, Ali

2017-02-01

Experiments and numerical simulations were carried out to examine the vertical impingement a round liquid jet on the edges of horizontal convex surfaces that were either superhydrophobic or hydrophobic. The experiments examine the effects on the flow behaviour of curvature, wettability, inertia of the jet, and the impingement rate. Three copper pipes with outer diameters of 15, 22, and 35 mm were investigated. The pipes were wrapped with a piece of a Brassica oleracea leaf or a smooth Teflon sheet, which have apparent contact angles of 160° and 113°. The Reynolds number ranged from 1000 to 4500, and the impingement rates of the liquid jets were varied. Numerical results show good agreement with the experimental results for explaining flow and provide detailed information about the impingement on the surfaces. The liquid jet reflected off the superhydrophobic surfaces for all conditions. However, the jet reflected or deflected off the hydrophobic surface, depending on the inertia of the jet, the curvature of the surface, and the impingement rate. The results suggest that pressure is not the main reason for the bending of the jet around the curved hydrophobic surface.

The Relationship Between Pulsatile Flow Impingement and Intraluminal Thrombus Deposition in Abdominal Aortic Aneurysms.

PubMed

Lozowy, Richard J; Kuhn, David C S; Ducas, Annie A; Boyd, April J

2017-03-01

Direct numerical simulations were performed on four patient-specific abdominal aortic aneurysm (AAA) geometries and the resulting pulsatile blood flow dynamics were compared to aneurysm shape and correlated with intraluminal thrombus (ILT) deposition. For three of the cases, turbulent vortex structures impinged/sheared along the anterior wall and along the posterior wall a zone of recirculating blood formed. Within the impingement region the AAA wall was devoid of ILT and remote to this region there was an accumulation of ILT. The high wall shear stress (WSS) caused by the impact of vortexes is thought to prevent the attachment of ILT. WSS from impingement is comparable to peak-systolic WSS in a normal-sized aorta and therefore may not damage the wall. Expansion occurred to a greater extent in the direction of jet impingement and the wall-normal force from the continuous impact of vortexes may contribute to expansion. It was shown that the impingement region has low oscillatory shear index (OSI) and recirculation zones can have either low or high OSI. No correlation could be identified between OSI and ILT deposition since different flow dynamics can have similar OSI values.

Three FORTRAN programs for finite-difference solutions to binary diffusion in one and two phases with composition-and time-dependent diffusion coefficients

USGS Publications Warehouse

Sanford, R.F.

1982-01-01

Geological examples of binary diffusion are numerous. They are potential indicators of the duration and rates of geological processes. Analytical solutions to the diffusion equations generally do not allow for variable diffusion coefficients, changing boundary conditions, and impingement of diffusion fields. The three programs presented here are based on Crank-Nicholson finite-difference approximations, which can take into account these complicating factors. Program 1 describes the diffusion of a component into an initially homogeneous phase that has a constant surface composition. Specifically it is written for Fe-Mg exchange in olivine at oxygen fugacities appropriate for the lunar crust, but other components, phases, or fugacities may be substituted by changing the values of the diffusion coefficient. Program 2 simulates the growth of exsolution lamellae. Program 3 describes the growth of reaction rims. These two programs are written for pseudobinary Ca-(Mg, Fe) exchange in pyroxenes. In all three programs, the diffusion coefficients and boundary conditions can be varied systematically with time. To enable users to employ widely different numerical values for diffusion coefficients and diffusion distance, the grid spacing in the space dimension and the increment by which the grid spacing in the time dimension is increased at each time step are input constants that can be varied each time the programs are run to yield a solution of the desired accuracy. ?? 1982.

An assessment of the liquid-gas partitioning behavior of major wastewater odorants using two comparative experimental approaches: liquid sample-based vaporization vs. impinger-based dynamic headspace extraction into sorbent tubes.

PubMed

Iqbal, Mohammad Asif; Kim, Ki-Hyun; Szulejko, Jan E; Cho, Jinwoo

2014-01-01

The gas-liquid partitioning behavior of major odorants (acetic acid, propionic acid, isobutyric acid, n-butyric acid, i-valeric acid, n-valeric acid, hexanoic acid, phenol, p-cresol, indole, skatole, and toluene (as a reference)) commonly found in microbially digested wastewaters was investigated by two experimental approaches. Firstly, a simple vaporization method was applied to measure the target odorants dissolved in liquid samples with the aid of sorbent tube/thermal desorption/gas chromatography/mass spectrometry. As an alternative method, an impinger-based dynamic headspace sampling method was also explored to measure the partitioning of target odorants between the gas and liquid phases with the same detection system. The relative extraction efficiency (in percent) of the odorants by dynamic headspace sampling was estimated against the calibration results derived by the vaporization method. Finally, the concentrations of the major odorants in real digested wastewater samples were also analyzed using both analytical approaches. Through a parallel application of the two experimental methods, we intended to develop an experimental approach to be able to assess the liquid-to-gas phase partitioning behavior of major odorants in a complex wastewater system. The relative sensitivity of the two methods expressed in terms of response factor ratios (RFvap/RFimp) of liquid standard calibration between vaporization and impinger-based calibrations varied widely from 981 (skatole) to 6,022 (acetic acid). Comparison of this relative sensitivity thus highlights the rather low extraction efficiency of the highly soluble and more acidic odorants from wastewater samples in dynamic headspace sampling.

[Posterior ankle impingement syndrome].

PubMed

Bojanić, Ivan; Janjić, Tamara; Dimnjaković, Damjan; Križan, Sanja; Smoljanović, Tomislav

2015-01-01

Posterior ankle impingement syndrome (PAIS) is a clinical syndrome characterized by posterior ankle pain which occurs in maximal forced plantar flexion of the foot. PAIS can be the result of an acute injury of the ankle, which is more often in general population, or it can be the result of the overuse syndrome, which is more often in athletes and ballet dancers. The etiology of PAIS may involve bony structures or soft tissue structures, or, more often, the combination of both. The diagnosis of PAIS is based on patient's clinical history and physical examination with the hyperplantarflexion test as a very important part of it. Physical examination should be completed with imaging techniques, which most often include magnetic resonance imaging (MRI) or computed tomography (CT) to confirm the diagnosis of PAIS. Conservative treatment is recommended as the primary treatment strategy. In those cases where 3 to 6 months of conservative treatment fails, open or, more often, arthroscopic/endoscopic surgery may be recommended. Nowadays, a 2-portal endoscopic approach introduced by van Dijk et al. in 2000 is the method of choice for the treatment of posterior ankle impingement syndrome.

Anterior ankle impingement after tendo-Achilles lengthening for long-standing equinus deformity in residual poliomyelitis.

PubMed

Sung, Ki Hyuk; Chung, Chin Youb; Lee, Kyoung Min; Lee, Seung Yeol; Park, Moon Seok

2013-09-01

This study was performed to investigate anterior ankle impingement after tendo-Achilles lengthening for long-standing equinus deformity in patients with residual poliomyelitis and to investigate whether the severity of preoperative equinus deformity affected the occurrence of symptomatic anterior impingement. Twenty-seven consecutive patients (mean age, 43.8 ± 9.4 years) with residual poliomyelitis who underwent tendo-Achilles lengthening for equinus foot deformity were included. On lateral foot-ankle weight-bearing radiographs, the tibiocalcaneal angle, plantigrade angle, and McDermott grade were measured and the presence of anterior blocking spur was evaluated. Eleven patients (40.7%) had anterior ankle impingement on radiographic findings preoperatively and 24 patients (88.9%) at latest follow-up. There was a significant difference in McDermott grade between preoperative and latest follow-up (P < .001). There were significant differences in tibiocalcaneal angle and plantigrade angle between the patients with anterior ankle pain and without anterior ankle pain (P = .006 and .011, respectively) and between the patients with anterior blocking spur and without anterior blocking spur (P = .005 and .010, respectively). Most patients with residual poliomyelitis had anterior ankle impingement after tendo-Achilles lengthening for long-standing equinus deformity, and the presence of symptomatic anterior ankle impingement was significantly associated with the severity of the equinus deformity. Therefore, for residual poliomyelitis patients with severe long-standing equinus deformity, surgeons should consider the possibility of a subsequent anterior procedure for anterior impingement after tendo-Achilles lengthening. Level IV, retrospective case series.

Experimental Optimisation of the Thermal Performance of Impinging Synthetic Jet Heat Sinks

NASA Astrophysics Data System (ADS)

Marron, Craig; Persoons, Tim

2014-07-01

Zero-net-mass flow synthetic jet devices offer a potential solution for energy- efficient cooling of medium power density electronic components. There remains an incomplete understanding of the interaction of these flows with extended surfaces, which prevents the wider implementation of these devices in the field. This study examines the effect of the main operating parameters on the heat transfer rate and electrical power consumption for a synthetic jet cooled heat sink. Three different heat sink geometries are tested. The results find that a modified sink with a 14 × 14 pin array with the central 6 × 6 pins removed provides superior cooling to either a fully pinned sink or flat plate. Furthermore each heat sink is found to have its own optimum jet orifice-to-sink spacing for heat transfer independent of flow conditions. The optimum heat transfer for the modified sink is H = 34 jet diameters. The effect of frequency on heat transfer is also studied. It is shown that heat transfer increases superlinearly with frequency at higher stroke lengths. The orientation of the impingement surface with respect to gravity has no effect on the heat transfer capabilities of the tested device. These tests are the starting point for further investigation into enhanced synthetic jet impingement surfaces. The equivalent axial fan cooled pinned heat sink (Malico Inc. MFP40- 18) has a thermal resistance of 1.93K/W at a fan power consumption of 0.12W. With the modified pinned heat sink, a synthetic jet at Re = 911, L0/D = 10, H/D = 30 provides a thermal resistance of 2.5K/W at the same power consumption.

High-order Two-way Artificial Boundary Conditions for Nonlinear Wave Propagation with Backscattering

NASA Technical Reports Server (NTRS)

Fibich, Gadi; Tsynkov, Semyon

2000-01-01

When solving linear scattering problems, one typically first solves for the impinging wave in the absence of obstacles. Then, by linear superposition, the original problem is reduced to one that involves only the scattered waves driven by the values of the impinging field at the surface of the obstacles. In addition, when the original domain is unbounded, special artificial boundary conditions (ABCs) that would guarantee the reflectionless propagation of waves have to be set at the outer boundary of the finite computational domain. The situation becomes conceptually different when the propagation equation is nonlinear. In this case the impinging and scattered waves can no longer be separated, and the problem has to be solved in its entirety. In particular, the boundary on which the incoming field values are prescribed, should transmit the given incoming waves in one direction and simultaneously be transparent to all the outgoing waves that travel in the opposite direction. We call this type of boundary conditions two-way ABCs. In the paper, we construct the two-way ABCs for the nonlinear Helmholtz equation that models the laser beam propagation in a medium with nonlinear index of refraction. In this case, the forward propagation is accompanied by backscattering, i.e., generation of waves in the direction opposite to that of the incoming signal. Our two-way ABCs generate no reflection of the backscattered waves and at the same time impose the correct values of the incoming wave. The ABCs are obtained for a fourth-order accurate discretization to the Helmholtz operator; the fourth-order grid convergence is corroborated experimentally by solving linear model problems. We also present solutions in the nonlinear case using the two-way ABC which, unlike the traditional Dirichlet boundary condition, allows for direct calculation of the magnitude of backscattering.

Experimental Study of Impinging Jets Flow-Fields

DTIC Science & Technology

2016-07-27

1 Grant # N000141410830 Experimental Study of Impinging Jet Flow-Fields Final Report for Period: Jun 15, 2014 – Jun 14, 2016 PI: Dennis K...impinging jet model in the absence of any jet heating. The results of the computations had been compared with the experimental data produced in the...of the validity of the computations, and also of the experimental approach. Figure 12a. Initial single

Plume Impingement Analysis for the European Service Module Propulsion System

NASA Technical Reports Server (NTRS)

Yim, John Tamin; Sibe, Fabien; Ierardo, Nicola

2014-01-01

Plume impingement analyses were performed for the European Service Module (ESM) propulsion system Orbital Maneuvering System engine (OMS-E), auxiliary engines, and reaction control system (RCS) engines. The heat flux from plume impingement on the solar arrays and other surfaces are evaluated. This information is used to provide inputs for the ESM thermal analyses and help determine the optimal configuration for the RCS engines.

Experimental Investigation of Water Droplet Impingement on Airfoils, Finite Wings, and an S-duct Engine Inlet

NASA Technical Reports Server (NTRS)

Papadakis, Michael; Hung, Kuohsing E.; Vu, Giao T.; Yeong, Hsiung Wei; Bidwell, Colin S.; Breer, Martin D.; Bencic, Timothy J.

2002-01-01

Validation of trajectory computer codes, for icing analysis, requires experimental water droplet impingement data for a wide range of aircraft geometries as well as flow and icing conditions. This report presents improved experimental and data reduction methods for obtaining water droplet impingement data and provides a comprehensive water droplet impingement database for a range of test geometries including an MS(1)-0317 airfoil, a GLC-305 airfoil, an NACA 65(sub 2)-415 airfoil, a commercial transport tail section, a 36-inch chord natural laminar flow NLF(1)-0414 airfoil, a 48-inch NLF(1)-0414 section with a 25 percent chord simple flap, a state-of-the-art three-element high lift system, a NACA 64A008 finite span swept business jet tail, a full-scale business jet horizontal tail section, a 25 percent-scale business jet empennage, and an S-duct turboprop engine inlet. The experimental results were obtained at the NASA Glenn Icing Research Tunnel (IRT) for spray clouds with median volumetric diameter (MVD) of 11, 11.5, 21, 92, and 94 microns and for a range of angles of attack. The majority of the impingement experiments were conducted at an air speed of 175 mph corresponding to a Reynolds number of approximately 1.6 million per foot. The maximum difference of repeated tests from the average ranged from 0.24 to 12 percent for most of the experimental results presented. This represents a significant improvement in test repeatability compared to previous experimental studies. The increase in test repeatability was attributed to improvements made to the experimental and data reduction methods. Computations performed with the LEWICE-2D and LEWICE-3D computer codes for all test configurations are presented in this report. For the test cases involving median volumetric diameters of 11 and 21 microns, the correlation between the analytical and experimental impingement efficiency distributions was good. For the median volumetric diameters of 92 and 94-micron cases, however, the analysis produced higher impingement efficiencies and larger impingement limits than the experiment. It is speculated that this discrepancy is due to droplet splashing and breakup experienced by large droplets during impingement.

A combined CFD-experimental method for developing an erosion equation for both gas-sand and liquid-sand flows

NASA Astrophysics Data System (ADS)

Mansouri, Amir

The surface degradation of equipment due to consecutive impacts of abrasive particles carried by fluid flow is called solid particle erosion. Solid particle erosion occurs in many industries including oil and gas. In order to prevent abrupt failures and costly repairs, it is essential to predict the erosion rate and identify the locations of the equipment that are mostly at risk. Computational Fluid Dynamics (CFD) is a powerful tool for predicting the erosion rate. Erosion prediction using CFD analysis includes three steps: (1) obtaining flow solution, (2) particle tracking and calculating the particle impact speed and angle, and (3) relating the particle impact information to mass loss of material through an erosion equation. Erosion equations are commonly generated using dry impingement jet tests (sand-air), since the particle impact speed and angle are assumed not to deviate from conditions in the jet. However, in slurry flows, a wide range of particle impact speeds and angles are produced in a single slurry jet test with liquid and sand particles. In this study, a novel and combined CFD/experimental method for developing an erosion equation in slurry flows is presented. In this method, a CFD analysis is used to characterize the particle impact speed, angle, and impact rate at specific locations on the test sample. Then, the particle impact data are related to the measured erosion depth to achieve an erosion equation from submerged testing. Traditionally, it was assumed that the erosion equation developed based on gas testing can be used for both gas-sand and liquid-sand flows. The erosion equations developed in this work were implemented in a CFD code, and CFD predictions were validated for various test conditions. It was shown that the erosion equation developed based on slurry tests can significantly improve the local thickness loss prediction in slurry flows. Finally, a generalized erosion equation is proposed which can be used to predict the erosion rate in gas-sand, water-sand and viscous liquid-sand flows with high accuracy. Furthermore, in order to gain a better understanding of the erosion mechanism, a comprehensive experimental study was conducted to investigate the important factors influencing the erosion rate in gas-sand and slurry flows. The wear pattern and total erosion ratio were measured in a direct impingement jet geometry (for both dry impact and submerged impingement jets). The effects of fluid viscosity, abrasive particle size, particle impact speed, jet inclination angle, standoff distance, sand concentration, and exposure time were investigated. Also, the eroded samples were studied with Scanning Electron Microscopy (SEM) to understand the erosion micro-structure. Also, the sand particle impact speed and angle were measured using a Particle Image Velocimetry (PIV) system. The measurements were conducted in two types of erosion testers (gas-solid and liquid-solid impinging jets). The Particle Tracking Velocimetry (PTV) technique was utilized which is capable of tracking individual small particles. Moreover, CFD modeling was performed to predict the particle impact data. Very good agreement between the CFD results and PTV measurements was observed.

Combined Anterolateral, Anterior, and Anteromedial Ankle Impingement in an Adolescent Soccer Player-A Case Report and Review of the Literature.

PubMed

Cosma, Dan I; Vasilescu, Dana E; Corbu, Andrei; Todor, Adrian; Valeanu, Madalina; Ulici, Alexandru

2018-01-24

A unique case of combined anterolateral, anterior, and anteromedial ankle impingement in an adolescent soccer player is presented in this article. To the best of our knowledge, this is the only report of circumferential, massive, anterior ankle impingement in children described in the literature. The importance of proper diagnosis and treatment of such a lesion is illustrated in this case report. We also emphasize that clinical examination combined with 3D computed tomography scan reconstruction is an excellent and cost-effective imaging modality that can help with the diagnosis of anterior ankle impingement. Finally, open surgical treatment showed excellent results in an elite athlete.

A multi-centre randomized controlled trial comparing arthroscopic osteochondroplasty and lavage with arthroscopic lavage alone on patient important outcomes and quality of life in the treatment of young adult (18-50) femoroacetabular impingement.

PubMed

2015-03-20

Several cross-sectional studies have estimated that the prevalence of femoroacetabular impingement (FAI) ranges from 14-17% among asymptomatic young adults to almost 95% among competitive athletes. With FAI, there is abnormal contact between the proximal femur and the acetabulum, resulting in abnormal mechanics with terminal motion such as hip flexion and rotation. This condition results from bony anomalies of the acetabular rim (Pincer) and or femoral head/neck junction (CAM) and typically causes hip pain and decreased hip function. The development of hip pain potentially serves as an indicator for early cartilage and labral damage that may result in hip osteoarthritis. Although surgical correction of the misshaped bony anatomy and associated intra-articular soft tissue damage of the hip is thought to improve hip pain and alter the natural history of degenerative disease, the supportive evidence is based upon low quality observational studies. The Femoroacetabular Impingement RandomiSed controlled Trial (FIRST) compares outcomes following surgical correction of the impingement morphology (arthroscopic osteochondroplasty) with/without labral repair versus arthroscopic lavage of the hip joint in adults aged 18 to 50 diagnosed with FAI. FIRST is a multi-centre, randomized controlled trial with a sample size of 220 patients. Exclusion criteria include the presence of hip syndromes, previous surgery or trauma to the affected hip, and significant medical comorbidities. The primary outcome is pain and the secondary outcomes include patient function, quality of life, complications, and cost-effectiveness--all within one year of follow-up. Patients are stratified based on centre and impingement sub-type. Patients, outcome assessors, data analysts, and the Steering Committee are blinded to surgical allocation. Using an intention-to-treat approach, outcome analyses will be performed using an analysis of covariance and descriptive statistics. Symptomatic FAI is associated with chronic hip pain, functional limitations, and secondary osteoarthritis. Therefore, optimizing treatment has the potential to improve the lives millions of young, active persons who are diagnosed with this condition. Few orthopaedic surgical trials have similar potential to shift the paradigm of care dramatically towards (or away) from surgical bony and soft tissue interventions. The FIRST trial is registered with clinicaltrials.gov (NCT01623843).

Jet impingement heat transfer enhancement for the GPU-3 Stirling engine

NASA Technical Reports Server (NTRS)

Johnson, D. C.; Congdon, C. W.; Begg, L. L.; Britt, E. J.; Thieme, L. G.

1981-01-01

A computer model of the combustion-gas-side heat transfer was developed to predict the effects of a jet impingement system and the possible range of improvements available. Using low temperature (315 C (600 F)) pretest data in an updated model, a high temperature silicon carbide jet impingement heat transfer system was designed and fabricated. The system model predicted that at the theoretical maximum limit, jet impingement enhanced heat transfer can: (1) reduce the flame temperature by 275 C (500 F); (2) reduce the exhaust temperature by 110 C (200 F); and (3) increase the overall heat into the working fluid by 10%, all for an increase in required pumping power of less than 0.5% of the engine power output. Initial tests on the GPU-3 Stirling engine at NASA-Lewis demonstrated that the jet impingement system increased the engine output power and efficiency by 5% - 8% with no measurable increase in pumping power. The overall heat transfer coefficient was increased by 65% for the maximum power point of the tests.

Rocket exhaust plume impingement on the Voyager spacecraft

NASA Technical Reports Server (NTRS)

Baerwald, R. K.

1978-01-01

In connection with the conduction of the long-duration Voyager missions to the outer planets and the sophisticated propulsion systems required, it was necessary to carry out an investigation to avoid exhaust plume impingement problems. The rarefied gas dynamics literature indicates that, for most engineering surfaces, the assumption of diffuse reemission and complete thermal accommodation is warranted in the free molecular flow regime. This assumption was applied to an analysis of a spacecraft plume impingement problem in the near-free molecular flow regime and yielded results to within a few percent of flight data. The importance of a correct treatment of the surface temperature was also demonstrated. Specular reflection, on the other hand, was shown to yield results which may be unconservative by a factor of 2 or 3. It is pointed out that one of the most difficult portions of an exhaust plume impingement analysis is the simulation of the impinged hardware. The geometry involved must be described as accurately and completely as possible.

Turbine stator vane segment having internal cooling circuits

DOEpatents

Jones, Raymond Joseph; Burns, James Lee; Bojappa, Parvangada Ganapathy; Jones, Schotsch Margaret

2003-01-01

A turbine stator vane includes outer and inner walls each having outer and inner chambers and a vane extending between the outer and inner walls. The vane includes first, second, third, fourth and fifth cavities for flowing a cooling medium. The cooling medium enters the outer chamber of the outer wall, flows through an impingement plate for impingement cooling of the outer band wall defining in part the hot gas path and through openings in the first, second and fourth cavities for flow radially inwardly, cooling the vane. The spent cooling medium flows into the inner wall and inner chamber for flow through an impingement plate radially outwardly to cool the inner wall. The spent cooling medium flows through the third cavity for egress from the turbine vane segment from the outer wall. The first, second or third cavities contain inserts having impingement openings for impingement cooling of the vane walls. The fifth cavity provides air cooling for the trailing edge.

A Dye-Tracer Technique for Experimentally Obtaining Impingement Characteristics of Arbitrary Bodies and a Method for Determining Droplet Size Distribution

NASA Technical Reports Server (NTRS)

VonGlahn, Uwe H.; Gelder, Thomas F.; Smyers, William H., Jr.

1955-01-01

A dye-tracer technique has been developed whereby the quantity of dyed water collected on a blotter-wrapped body exposed to an air stream containing a dyed-water spray cloud can be colorimetrically determined in order to obtain local collection efficiencies, total collection efficiency, and rearward extent of impingement on the body. In addition, a method has been developed whereby the impingement characteristics obtained experimentally for a body can be related to theoretical impingement data for the same body in order to determine the droplet size distribution of the impinging cloud. Several cylinders, a ribbon, and an aspirating device to measure cloud liquid-water content were used in the studies presented herein for the purpose of evaluating the dye-tracer technique. Although the experimental techniques used in the dye-tracer technique require careful control, the methods presented herein should be applicable for any wind tunnel provided the humidity of the air stream can be maintained near saturation.

Arthroscopic debridement for soft tissue ankle impingement.

PubMed

Brennan, S A; Rahim, F; Dowling, J; Kearns, S R

2012-06-01

To assess the response to treatment in patients with soft tissue impingement of the ankle managed with arthroscopic debridement. Forty-one ankle arthroscopies were performed for soft tissue impingement between April 2007 and April 2009. There were 26 men and 15 women and the mean age was 30.1 years. Arthroscopy was performed on an average of 21 months after injury. The Visual-Analogue-Scale Foot and Ankle (VASFA) score and Meislin's criteria were used to assess the response to treatment. The mean pre-operative VASFA score was 44.5. This increased to 78.3 postoperatively (p < 0.0001). According to Meislin's criteria, there were 34 good or excellent results, five fair and two poor results. Pre-operative magnetic resonance imaging was useful in detecting tears of the anterior talofibular ligament and excluding osteochondral defects; however, synovitis and soft tissue impingement was under-reported. Arthroscopy is an effective method for the diagnoses and treatment of soft tissue impingement of the ankle joint. This condition is under-reported on MRI.

Bucket platform cooling scheme and related method

DOEpatents

Abuaf, Nesim; Barb, Kevin Joseph; Chopra, Sanjay; Kercher, David Max; Kellock, Iain Robertson; Lenahan, Dean Thomas; Nellian, Sankar; Starkweather, John Howard; Lupe, Douglas Arthur

2002-01-01

A turbine bucket includes an airfoil extending from a platform, having high and low pressure sides; a wheel mounting portion; a hollow shank portion located radially between the platform and the wheel mounting portion, the platform having an under surface. An impingement cooling plate is located in the hollow shank portion, spaced from the under surface, and the impingement plate is formed with a plurality of impingement cooling holes therein.

Heat Transfer of Confined Impinging Air-water Mist Jet

NASA Astrophysics Data System (ADS)

Chang, Shyy Woei; Su, Lo May

This paper describes the detailed heat transfer distributions of an atomized air-water mist jet impinging orthogonally onto a confined target plate with various water-to-air mass-flow ratios. A transient technique was used to measure the full field heat transfer coefficients of the impinging surface. Results showed that the high momentum mist-jet interacting with the water-film and wall-jet flows created a variety of heat transfer contours on the impinging surface. The trade-off between the competing influences of the different heat transfer mechanisms involving in an impinging mist jet made the nonlinear variation tendency of overall heat transfer against the increase of water-to-air mass-flow ratio and extended the effective cooling region. With separation distances of 10, 8, 6 and 4 jet-diameters, the spatially averaged heat transfer values on the target plate could respectively reach about 2.01, 1.83, 2.43 and 2.12 times of the equivalent air-jet values, which confirmed the applicability of impinging mist-jet for heat transfer enhancement. The optimal choices of water-to-air mass-flow ratio for the atomized mist jet required the considerations of interactive and combined effects of separation distance, air-jet Reynolds number and the water-to-air mass-flow ratio into the atomized nozzle.

GUI to Facilitate Research on Biological Damage from Radiation

NASA Technical Reports Server (NTRS)

Cucinotta, Frances A.; Ponomarev, Artem Lvovich

2010-01-01

A graphical-user-interface (GUI) computer program has been developed to facilitate research on the damage caused by highly energetic particles and photons impinging on living organisms. The program brings together, into one computational workspace, computer codes that have been developed over the years, plus codes that will be developed during the foreseeable future, to address diverse aspects of radiation damage. These include codes that implement radiation-track models, codes for biophysical models of breakage of deoxyribonucleic acid (DNA) by radiation, pattern-recognition programs for extracting quantitative information from biological assays, and image-processing programs that aid visualization of DNA breaks. The radiation-track models are based on transport models of interactions of radiation with matter and solution of the Boltzmann transport equation by use of both theoretical and numerical models. The biophysical models of breakage of DNA by radiation include biopolymer coarse-grained and atomistic models of DNA, stochastic- process models of deposition of energy, and Markov-based probabilistic models of placement of double-strand breaks in DNA. The program is designed for use in the NT, 95, 98, 2000, ME, and XP variants of the Windows operating system.

Loci-STREAM Version 0.9

NASA Technical Reports Server (NTRS)

Wright, Jeffrey; Thakur, Siddharth

2006-01-01

Loci-STREAM is an evolving computational fluid dynamics (CFD) software tool for simulating possibly chemically reacting, possibly unsteady flows in diverse settings, including rocket engines, turbomachines, oil refineries, etc. Loci-STREAM implements a pressure- based flow-solving algorithm that utilizes unstructured grids. (The benefit of low memory usage by pressure-based algorithms is well recognized by experts in the field.) The algorithm is robust for flows at all speeds from zero to hypersonic. The flexibility of arbitrary polyhedral grids enables accurate, efficient simulation of flows in complex geometries, including those of plume-impingement problems. The present version - Loci-STREAM version 0.9 - includes an interface with the Portable, Extensible Toolkit for Scientific Computation (PETSc) library for access to enhanced linear-equation-solving programs therein that accelerate convergence toward a solution. The name "Loci" reflects the creation of this software within the Loci computational framework, which was developed at Mississippi State University for the primary purpose of simplifying the writing of complex multidisciplinary application programs to run in distributed-memory computing environments including clusters of personal computers. Loci has been designed to relieve application programmers of the details of programming for distributed-memory computers.

Performance outlook of the SCRAP receiver

NASA Astrophysics Data System (ADS)

Lubkoll, Matti; von Backström, Theodor W.; Harms, Thomas M.

2016-05-01

A combined cycle (CC) concentrating solar power (CSP) plant provides significant potential to achieve an efficiency increase and an electricity cost reduction compared to current single-cycle plants. A CC CSP system requires a receiver technology capable of effectively transferring heat from concentrated solar irradiation to a pressurized air stream of a gas turbine. The small number of pressurized air receivers demonstrated to date have practical limitations, when operating at high temperatures and pressures. As yet, a robust, scalable and efficient system has to be developed and commercialized. A novel receiver system, the Spiky Central Receiver Air Pre-heater (SCRAP) concept has been proposed to comply with these requirements. The SCRAP system is conceived as a solution for an efficient and robust pressurized air receiver that could be implemented in CC CSP concepts or standalone solar Brayton cycles without a bottoming Rankine cycle. The presented work expands on previous publications on the thermal modeling of the receiver system. Based on the analysis of a single heat transfer element (spike), predictions for its thermal performance can be made. To this end the existing thermal model was improved by heat transfer characteristics for the jet impingement region of the spike tip as well as heat transfer models simulating the interaction with ambient. While the jet impingement cooling effect was simulated employing a commercial CFD code, the ambient heat transfer model was based on simplifying assumptions in order to employ empirical and analytical equations. The thermal efficiency of a spike under design conditions (flux 1.0 MW/m2, air outlet temperature just below 800 °C) was calculated at approximately 80 %, where convective heat losses account for 16.2 % of the absorbed radiation and radiative heat losses for a lower 2.9 %. This effect is due to peak surface temperatures occurring at the root of the spikes. It can thus be concluded that the geometric receiver layout assists to limit radiative heat losses.

Trunk and lower limb biomechanics during stair climbing in people with and without symptomatic femoroacetabular impingement.

PubMed

Hammond, Connor A; Hatfield, Gillian L; Gilbart, Michael K; Garland, S Jayne; Hunt, Michael A

2017-02-01

Femoroacetabular impingement is a pathomechanical hip condition leading to pain and impaired physical function. It has been shown that those with femoroacetabular impingement exhibit altered gait characteristics during level walking and stair climbing, and decreased muscle force production during isometric muscle contractions. However, no studies to-date have looked at trunk kinematics or muscle activation during dynamic movements such as stair climbing in this patient population. The purpose of this study was to compare biomechanical outcomes (trunk and lower limb kinematics as well as lower limb kinetics and muscle activation) during stair climbing in those with and without symptomatic femoroacetabular impingement. Trunk, hip, knee and ankle kinematics, as well as hip, knee and ankle kinetics and muscle activity of nine lower limb muscles were collected during stair climbing for 20 people with clinical and radiographic femoroacetabular impingement and compared to 20 age- and sex-matched pain-free individuals. Those with femoroacetabular impingement ascended the stairs slower (effect size=0.82), had significantly increased peak trunk forward flexion angles (effect size=0.99) and external hip flexion moments (effect size=0.94) and had decreased peak external knee flexion moments (effect size=0.90) compared to the control group. Findings from this study indicate that while those with and without femoroacetabular impingement exhibit many biomechanical similarities when ascending stairs, differences in trunk forward flexion and joint kinetics indicate some important differences. Further longitudinal research is required to elucidate the cause of these differences as well as the clinical relevance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Turbine vane segment and impingement insert configuration for fail-safe impingement insert retention

DOEpatents

Burdgick, Steven Sebastian; Kellock, Iain Robertson

2003-05-13

An impingement insert sleeve is provided that is adapted to be disposed in a coolant cavity defined through a stator vane. The insert has a generally open inlet end and first and second pairs of diametrically opposed side walls, and at least one fail-safe tab defined at a longitudinal end of the insert for limiting radial displacement of the insert with respect to the stator vane.

Sequential cooling insert for turbine stator vane

DOEpatents

Jones, Russel B

2017-04-04

A sequential flow cooling insert for a turbine stator vane of a small gas turbine engine, where the impingement cooling insert is formed as a single piece from a metal additive manufacturing process such as 3D metal printing, and where the insert includes a plurality of rows of radial extending impingement cooling air holes alternating with rows of radial extending return air holes on a pressure side wall, and where the insert includes a plurality of rows of chordwise extending second impingement cooling air holes on a suction side wall. The insert includes alternating rows of radial extending cooling air supply channels and return air channels that form a series of impingement cooling on the pressure side followed by the suction side of the insert.

Vortex Structure Effects on Impingement, Effusion, and Cross Flow Cooling of a Double Wall Configuration

NASA Astrophysics Data System (ADS)

Ligrani, P. M.

2018-03-01

A variety of different types of vortices and vortex structures have important influences on thermal protection, heat transfer augmentation, and cooling performance of impingement cooling, effusion cooling, and cross flow cooling. Of particular interest are horseshoe vortices, which form around the upstream portions of effusion coolant concentrations just after they exit individual holes, hairpin vortices, which develop nearby and adjacent to effusion coolant trajectories, and Kelvin-Helmholtz vortices which form within the shear layers that form around each impingement cooling jet. The influences of these different vortex structures are described as they affect and alter the thermal performance of effusion cooling, impingement cooling, and cross flow cooling, as applied to a double wall configuration.

Numerical modeling of runback water on ice protected aircraft surfaces

NASA Technical Reports Server (NTRS)

Al-Khalil, Kamel M.; Keith, Theo G., Jr.; Dewitt, Kenneth J.

1992-01-01

A numerical simulation for 'running wet' aircraft anti-icing systems is developed. The model includes breakup of the water film, which exists in regions of direct impingement, into individual rivulets. The wetness factor distribution resulting from the film breakup and the rivulet configuration on the surface are predicted in the numerical solution procedure. The solid wall is modeled as a multilayer structure and the anti-icing system used is of the thermal type utilizing hot air and/or electrical heating elements embedded with the layers. Details of the calculation procedure and the methods used are presented.

Unsteady adjoint for large eddy simulation of a coupled turbine stator-rotor system

NASA Astrophysics Data System (ADS)

Talnikar, Chaitanya; Wang, Qiqi; Laskowski, Gregory

2016-11-01

Unsteady fluid flow simulations like large eddy simulation are crucial in capturing key physics in turbomachinery applications like separation and wake formation in flow over a turbine vane with a downstream blade. To determine how sensitive the design objectives of the coupled system are to control parameters, an unsteady adjoint is needed. It enables the computation of the gradient of an objective with respect to a large number of inputs in a computationally efficient manner. In this paper we present unsteady adjoint solutions for a coupled turbine stator-rotor system. As the transonic fluid flows over the stator vane, the boundary layer transitions to turbulence. The turbulent wake then impinges on the rotor blades, causing early separation. This coupled system exhibits chaotic dynamics which causes conventional adjoint solutions to diverge exponentially, resulting in the corruption of the sensitivities obtained from the adjoint solutions for long-time simulations. In this presentation, adjoint solutions for aerothermal objectives are obtained through a localized adjoint viscosity injection method which aims to stabilize the adjoint solution and maintain accurate sensitivities. Preliminary results obtained from the supercomputer Mira will be shown in the presentation.

The risks of aorta impingement from pedicle screw may increase due to aorta movement during posterior instrumentation in Lenke 5C curve: a computed tomography study.

PubMed

Chen, Ling; Xu, Leilei; Qiu, Yong; Qiao, Jun; Wang, Fei; Liu, Zhen; Shi, Benglong; Qian, Bang-ping; Zhu, Zezhang

2015-07-01

To investigate the aorta movement following correction surgery for patients with thoracolumbar/lumbar scoliosis and to determine the subsequent risk of the aorta impingement for pedicle screw (PS) misplacement. Thirty-six AIS patients with a main thoracolumbar or lumbar curve were included in this study. According to the direction of the main curve, the patients were divided into Group R and Group L, with Group R comprising 16 patients with a right-sided curve and Group L comprising 20 patients with a left-sided curve. All patients underwent CT scans of the lower thoracic and lumbar spine before and after surgery. To identify the relative positions of the aorta to vertebral body, several parameters were measured from the CT images of the middle transverse planes of vertebrae from T11 to L4, including aorta-vertebra angle (α), vertebral rotation angle (β), left safety distance (LSD) and right safety distance (RSD). The risk of the aorta impingement from T11 to L4 was calculated. An intragroup comparison regarding the position of the aorta relative to the vertebral body before and after correction surgery was performed accordingly. After surgery, the aorta moved toward the vertebral body among all levels in both groups. Compared with that in Group L, the aorta in Group R was significantly closer to the entry point at all levels, especially at T11. Before surgery, the aorta in Group R was at a high risk of impingement from left PS placement regardless of the diameters of the simulated screws. While in Group L, the risk of aorta impingement was mainly caused by the right placement of 45 mm PS. After surgery, both groups had an increased risk of aorta impingement from PS insertion, especially at T11. The risk of aorta impingement from PS placement was significantly higher in Group R than in Group L. The risk of aorta impingement increased as the aorta shifted leftward after correction surgery, especially in right-sided Lenke 5C curve. Thus, preoperative risk evaluation could be insufficient for clinical practice due to aorta movement following correction surgery. Surgeons should be aware of the potential risk of aorta impingement, especially when placing PS in patients with right-sided curves.

Effect of baseplate size on primary glenoid stability and impingement-free range of motion in reverse shoulder arthroplasty.

PubMed

Chae, Soo-Won; Kim, Soung-Yon; Lee, Haea; Yon, Joung-Ro; Lee, Juneyoung; Han, Seung-Ho

2014-12-09

Use of a baseplate with a smaller diameter in reverse shoulder arthroplasty is increasing, especially in patients with a small glenoid or glenoid wear. However, the effect of a smaller baseplate on stability of the glenoid component has not been evaluated. Thus, the purpose of this study was to determine whether a smaller baseplate (25 mm) is beneficial to the initial stability of the glenoid component compared to that with a baseplate of a commonly used size (29 mm). Micromotion of glenoid components attached to 14 scapulae of fresh-frozen cadavers was measured and compared between 25- and 29-mm baseplates in biomechanical testing. Impingement-free range of motion in abduction, adduction, internal rotation, and external rotation was evaluated by using a simulated computer model constructed based on the same fresh-frozen cadavers used in biomechanical testing. Micromotion at the inferior third of the glenoid-glenosphere interface was higher in the 29-mm baseplate group than in the 25-mm baseplate group during both 0.7- and 1-body weight cyclic loading in biomechanical testing. Adduction deficit was smaller, and total impingement-free range of motion from abduction to adduction and rotation were greater in the 25-mm baseplate group than in the 29-mm baseplate group in the simulated computer model. Use of a baseplate with a smaller diameter (25 mm) in reverse shoulder arthroplasty is suitable for improving the primary stability of the glenoid component. With a smaller baseplate, impingement-free range of motion is optimized in a smaller glenoid.

Evaluating the Role of Subacromial Impingement in Rotator Cuff tendinopathy: Development and Analysis of a Novel Murine Model.

PubMed

Cong, Guang-Ting; Lebaschi, Amir H; Camp, Christopher L; Carballo, Camila B; Nakagawa, Yusuke; Wada, Susumu; Deng, Xiang-Hua; Rodeo, Scott A

2018-04-23

Subacromial impingement of the rotator cuff is understood as a contributing factor in the development of rotator cuff tendinopathy. However, changes that occur in the impinged tendon are poorly understood and warrant further study. To enable further study of rotator cuff tendinopathy, we performed a controlled laboratory study to determine feasibility and baseline characteristics of a new murine model for subacromial impingement. This model involves surgically inserting a microvascular clip into the subacromial space in adult C57Bl/6 mice. Along with a sham surgery arm, 90 study animals were distributed among time point groups for sacrifice up to 6 weeks. All animals underwent bilateral surgery (total N = 180). Biomechanical, histologic, and molecular analyses were performed to identify and quantify the progression of changes in the supraspinatus tendon. Decreases in failure force and stiffness were found in impinged tendon specimens compared to sham and no-surgery controls at all study time points. Semi-quantitative scoring of histologic specimens demonstrated significant, persistent tendinopathic changes over 6 weeks. Quantitative real-time polymerase chain reaction analysis of impinged tendon specimens demonstrated persistently increased expression of genes related to matrix remodeling, inflammation, and tendon development. Overall, this novel murine subacromial impingement model creates changes consistent with acute tendonitis, which may mimic the early stages of rotator cuff tendinopathy. This article is protected by copyright. All rights reserved Clinical Significance: A robust, simple, and reproducible animal model of rotator cuff tendinopathy is a valuable research tool to allow further studies of cellular and molecular mechanisms and evaluation of therapeutic interventions in rotator cuff tendinopathy. This article is protected by copyright. All rights reserved.

Cleaning verification by air/water impingement

NASA Technical Reports Server (NTRS)

Jones, Lisa L.; Littlefield, Maria D.; Melton, Gregory S.; Caimi, Raoul E. B.; Thaxton, Eric A.

1995-01-01

This paper will discuss how the Kennedy Space Center intends to perform precision cleaning verification by Air/Water Impingement in lieu of chlorofluorocarbon-113 gravimetric nonvolatile residue analysis (NVR). Test results will be given that demonstrate the effectiveness of the Air/Water system. A brief discussion of the Total Carbon method via the use of a high temperature combustion analyzer will also be given. The necessary equipment for impingement will be shown along with other possible applications of this technology.

Hot air impingement on a flat plate using Large Eddy Simulation (LES) technique

NASA Astrophysics Data System (ADS)

Plengsa-ard, C.; Kaewbumrung, M.

2018-01-01

Impinging hot gas jets to a flat plate generate very high heat transfer coefficients in the impingement zone. The magnitude of heat transfer prediction near the stagnation point is important and accurate heat flux distribution are needed. This research studies on heat transfer and flow field resulting from a single hot air impinging wall. The simulation is carried out using computational fluid dynamics (CFD) commercial code FLUENT. Large Eddy Simulation (LES) approach with a subgrid-scale Smagorinsky-Lilly model is present. The classical Werner-Wengle wall model is used to compute the predicted results of velocity and temperature near walls. The Smagorinsky constant in the turbulence model is set to 0.1 and is kept constant throughout the investigation. The hot gas jet impingement on the flat plate with a constant surface temperature is chosen to validate the predicted heat flux results with experimental data. The jet Reynolds number is equal to 20,000 and a fixed jet-to-plate spacing of H/D = 2.0. Nusselt number on the impingement surface is calculated. As predicted by the wall model, the instantaneous computed Nusselt number agree fairly well with experimental data. The largest values of calculated Nusselt number are near the stagnation point and decrease monotonically in the wall jet region. Also, the contour plots of instantaneous values of wall heat flux on a flat plate are captured by LES simulation.

Experiments on free and impinging supersonic microjets

NASA Astrophysics Data System (ADS)

Phalnikar, K. A.; Kumar, R.; Alvi, F. S.

2008-05-01

The fluid dynamics of microflows has recently commanded considerable attention because of their potential applications. Until now, with a few exceptions, most of the studies have been limited to low speed flows. This experimental study examines supersonic microjets of 100-1,000 μm in size with exit velocities in the range of 300-500 m/s. Such microjets are presently being used to actively control larger supersonic impinging jets, which occur in STOVL (short takeoff and vertical landing) aircraft, cavity flows, and flow separation. Flow properties of free as well as impinging supersonic microjets have been experimentally investigated over a range of geometric and flow parameters. The flowfield is visualized using a micro-schlieren system with a high magnification. These schlieren images clearly show the characteristic shock cell structure typically observed in larger supersonic jets. Quantitative measurements of the jet decay and spreading rates as well as shock cell spacing are obtained using micro-pitot probe surveys. In general, the mean flow features of free microjets are similar to larger supersonic jets operating at higher Reynolds numbers. However, some differences are also observed, most likely due to pronounced viscous effects associated with jets at these small scales. Limited studies of impinging microjets were also conducted. They reveal that, similar to the behavior of free microjets, the flow structure of impinging microjets strongly resembles that of larger supersonic impinging jets.

Evaluation of Impinging Stream Vortex Chamber Concepts for Liquid Rocket Engine Applications

NASA Technical Reports Server (NTRS)

Trinh, Huu; Kopicz, Charles; Bullard, Brad; Michaels, Scott

2003-01-01

NASA Marshall Space Flight Center (MSFC) and the U. S. Army are jointly investigating vortex chamber concepts for cryogenic oxygen/hydrocarbon fuel rocket engine applications. One concept, the Impinging Stream Vortex Chamber Concept (ISVC), has been tested with gel propellants at AMCOM at Redstone Arsenal, Alabama. A version of this concept for the liquid oxygen (LOX)/hydrocarbon fuel (RP-1) propellant system is derived from the one for the gel propellant. An unlike impinging injector is employed to deliver the propellants to the chamber. MSFC has also designed two alternative injection schemes, called the chasing injectors, associated with this vortex chamber concept. In these injection techniques, both propellant jets and their impingement point are in the same chamber cross-sectional plane. One injector has a similar orifice size with the original unlike impinging injector. The second chasing injector has small injection orifices. The team has achieved their objectives of demonstrating the self-cooled chamber wall benefits of ISVC and of providing the test data for validating computational fluids dynamics (CFD) models. These models, in turn, will be used to design the optimum vortex chambers in the future.

Unconstrained tripolar hip implants: effect on hip stability.

PubMed

Guyen, Olivier; Chen, Qing Shan; Bejui-Hugues, Jacques; Berry, Daniel J; An, Kai-Nan

2007-02-01

Tripolar implants were developed to treat unstable total hip arthroplasties. However, there is limited confirmation that they achieve this purpose despite their increasing use. Because they have a larger effective head size, these implants are expected to increase range of motion to impingement and improve stability in situations at risk for impingement compared with conventional implants. We assessed the range of motion to impingement using a tripolar implant mounted to an automated hip simulator using 22.2-mm and 28-mm femoral head sizes. The 22 and 28-mm tripolar implants provided increases of 30.5 degrees in flexion, 15.4 degrees in adduction, and 22.4 degrees in external rotation compared with the conventional 22.2-mm femoral head diameter implant. At the critical position of 90 degrees hip flexion, there was an increase of 45.2 degrees in internal rotation. At 0 degrees and 30 degrees external rotation, extension increases were 18.8 degrees and 7.8 degrees, respectively. Bony impingement was the limiting factor. Tripolar implants increased the arc of motion before impingement in positions at risk for dislocation and are expected to provide greater stability.

Space shuttle vehicle rocket plume impingement study for separation analysis. Tasks 2 and 3: Definition and preliminary plume impingement analysis for the MSC booster

NASA Technical Reports Server (NTRS)

Wojciechowski, C. J.; Penny, M. M.; Prozan, R. J.

1970-01-01

The results are presented of a space shuttle plume impingement study for the Manned Spacecraft Center configuration. This study was conducted as two tasks which were to (1) define the orbiter main stage engine exhaust plume flow field, and (2) define the plume impingement heating, force and resulting moment environments on the booster during the staging maneuver. To adequately define these environments during the staging maneuver and allow for deviation from the nominal separation trajectory, a multitude of relative orbiter/booster positions are analyzed which map the region that contains the separation trajectories. The data presented can be used to determine a separation trajectory which will result in acceptable impingement heating rates, forces, and the resulting moments. The data, presented in graphical form, include the effect of roll, pitch and yaw maneuvers for the booster. Quasi-steady state analysis methods were used with the orbiter engine operating at full thrust. To obtain partial thrust results, simple ratio equations are presented.

2,4 - dinitrophenylhydrazine - coated silica gel cartridge method for determination of formaldehyde in air: Identification of an ozone interference

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

Arnts, R.R.; Tejada, S.B.

1989-01-01

Two versions of the 2,4-dinitrophenylhydrazine method, a coated silica gel cartridge (solid) and acetonitrile impinger (solvent based), were used simultaneously to sample varied concentrations of ozone (0-770 ppb) and formaldehyde (20-140 ppb). Ozone was found to be a negative interference in the determination of formaldehyde by the 2,4-dinitrophenylhydrazine-coated silica gel cartridge method. At 120 ppb of ozone, formaldehyde at 40 ppb was under-reported by the cartridge method by 34% and at 300 ppb of ozone, formaldehyde measurements were 61% low. Greater losses were seen at higher ozone concentrations. Impinger sampling (2,4-DNPH in acetonitrile) showed no formaldehyde losses due to ozone.

Effect of coating material on heat transfer and skin friction due to impinging jet onto a laser producedhole

NASA Astrophysics Data System (ADS)

Shuja, S. Z.; Yilbas, B. S.

2013-07-01

Jet impingement onto a two-layer structured hole in relation to laser drilling is investigated. The hole consists of a coating layer and a base material. The variations in the Nusselt number and the skin friction are predicted for various coating materials. The Reynolds stress turbulent model is incorporated to account for the turbulence effect of the jet flow and nitrogen is used as the working fluid. The study is extended to include two jet velocities emanating from the conical nozzle. It is found that coating material has significant effect on the Nusselt number variation along the hole wall. In addition, the skin friction varies considerably along the coating thickness in thehole.

CPV cells cooling system based on submerged jet impingement: CFD modeling and experimental validation

NASA Astrophysics Data System (ADS)

Montorfano, Davide; Gaetano, Antonio; Barbato, Maurizio C.; Ambrosetti, Gianluca; Pedretti, Andrea

2014-09-01

Concentrating photovoltaic (CPV) cells offer higher efficiencies with regard to the PV ones and allow to strongly reduce the overall solar cell area. However, to operate correctly and exploit their advantages, their temperature has to be kept low and as uniform as possible and the cooling circuit pressure drops need to be limited. In this work an impingement water jet cooling system specifically designed for an industrial HCPV receiver is studied. Through the literature and by means of accurate computational fluid dynamics (CFD) simulations, the nozzle to plate distance, the number of jets and the nozzle pitch, i.e. the distance between adjacent jets, were optimized. Afterwards, extensive experimental tests were performed to validate pressure drops and cooling power simulation results.

Physical Therapy Protocol After Hip Arthroscopy: Clinical Guidelines Supported by 2-Year Outcomes.

PubMed

Domb, Benjamin G; Sgroi, Terrance A; VanDevender, Jeremy C

2016-07-01

Femoroacetabular impingement (FAI) was first described by Ganz in 2003 and is a significant cause of decreased function and mobility. Femoroacetabular impingement must be treated in an individualized, goal-oriented, stepwise fashion. This protocol was developed with biomechanical considerations of soft tissue and bony structures surrounding the hip joint. The PubMed database was searched for scientific and review articles from the years 2000 to 2015 utilizing the search terms: hip rehabilitation, femoroacetabular impingement, and arthroscopy. Clinical review. Level 5. Five hundred ninety-five of 738 patients were available for follow-up showing improvement from preoperative to 2-year follow-up of 61.29 to 82.02 for modified Harris Hip Score (mHHS), 62.79 to 83.04 for Hip Outcome Score-Activities of Daily Living (HOS-ADL), 40.96 to 70.07 for Hip Outcome Score-Sport-Specific Subscale (HOS-SSS), and 57.97 to 80.41 for Non-Arthritic Hip Score (NAHS); visual analog scale (VAS) scores decreased from 5.86 preoperatively to 2.94 postoperatively. Following a structured, criteria-based program, appropriate patients undergoing hip arthroscopy may achieve excellent outcomes and return to full independent activities of daily living as well as sport. © 2016 The Author(s).

Physical Therapy Protocol After Hip Arthroscopy

PubMed Central

Domb, Benjamin G.; Sgroi, Terrance A.; VanDevender, Jeremy C.

2016-01-01

Context: Femoroacetabular impingement (FAI) was first described by Ganz in 2003 and is a significant cause of decreased function and mobility. Femoroacetabular impingement must be treated in an individualized, goal-oriented, stepwise fashion. This protocol was developed with biomechanical considerations of soft tissue and bony structures surrounding the hip joint. Evidence Acquisition: The PubMed database was searched for scientific and review articles from the years 2000 to 2015 utilizing the search terms: hip rehabilitation, femoroacetabular impingement, and arthroscopy. Study Design: Clinical review. Level of Evidence: Level 5. Results: Five hundred ninety-five of 738 patients were available for follow-up showing improvement from preoperative to 2-year follow-up of 61.29 to 82.02 for modified Harris Hip Score (mHHS), 62.79 to 83.04 for Hip Outcome Score–Activities of Daily Living (HOS-ADL), 40.96 to 70.07 for Hip Outcome Score–Sport-Specific Subscale (HOS-SSS), and 57.97 to 80.41 for Non-Arthritic Hip Score (NAHS); visual analog scale (VAS) scores decreased from 5.86 preoperatively to 2.94 postoperatively. Conclusion: Following a structured, criteria-based program, appropriate patients undergoing hip arthroscopy may achieve excellent outcomes and return to full independent activities of daily living as well as sport. PMID:27173983

An Empirical Method Permitting Rapid Determination of the Area, Rate and Distribution of Water-Drop Impingement on an Airfoil of Arbitrary Section at Subsonic Speeds

NASA Technical Reports Server (NTRS)

Bergrun, N. R.

1951-01-01

An empirical method for the determination of the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The procedure represents an initial step toward the development of a method which is generally applicable in the design of thermal ice-prevention equipment for airplane wing and tail surfaces. Results given by the proposed empirical method are expected to be sufficiently accurate for the purpose of heated-wing design, and can be obtained from a few numerical computations once the velocity distribution over the airfoil has been determined. The empirical method presented for incompressible flow is based on results of extensive water-drop. trajectory computations for five airfoil cases which consisted of 15-percent-thick airfoils encompassing a moderate lift-coefficient range. The differential equations pertaining to the paths of the drops were solved by a differential analyzer. The method developed for incompressible flow is extended to the calculation of area and rate of impingement on straight wings in subsonic compressible flow to indicate the probable effects of compressibility for airfoils at low subsonic Mach numbers.

Erosion onset of a cohesionless granular medium by an immersed impinging round jet

NASA Astrophysics Data System (ADS)

Brunier-Coulin, Florian; Cuéllar, Pablo; Philippe, Pierre

2017-03-01

Among different devices developed quite recently to quantify the resistance to erosion of natural soil within the broader context of dyke safety, the most commonly used is probably the jet erosion test in which a scouring crater is induced by impingement of an immersed water jet. A comprehensive experimental investigation on the jet erosion in the specific situation of a cohesionless granular material is presented here. The tests were performed by combining special optical techniques allowing for an accurate measurement of the scouring onset and evolution inside an artificially translucent granular sample. The impinging jet hydrodynamics are also analyzed, empirically validating the use of a self-similar theoretical framework for the laminar round jet. The critical conditions at the onset of erosion appear to be best described by a dimensionless Shields number based on the inertial drag force created by the fluid flow on the eroded particles rather than on the pressure gradients around them. To conclude, a tentative empirical model for the maximal flow velocity initiating erosion at the bottom of the scoured crater is put forward and discussed in the light of some preliminary results.

Effects of Non-Uniform Inlet Temperature Distribution on High-Pressure Turbine Blade Loading

NASA Astrophysics Data System (ADS)

Smith, Craig I.; Chang, Dongil; Tavoularis, Stavros

2012-09-01

The effects of a non-uniform inlet field on the performance of a commercial, transonic, single-stage, high-pressure, axial turbine with a curved inlet duct have been investigated numerically by solving the unsteady Reynolds-averaged Navier-Stokes equations with the shear stress transport (SST) turbulence model. By adjusting the alignment of the experimentally-based inlet temperature field with respect to the stator vanes, two clocking configurations were generated: a Vane-Impinging (VI) case, in which each hot streak impinged on a vane and a Mid-Pitch (MP) case, in which each hot streak passed between two vanes. An additional case with a purely radial (PR) variation of inlet temperature was also investigated. In the VI case, it was observed that, as the hot streaks impinged on the stator vanes, they spread spanwise due to the actions of the casing passage vortices and the radial pressure gradient; this resulted in a stream entering the rotor with relatively low temperature variations. In the MP case, the hot streaks were convected undisturbed past the relatively cool vane section. Relatively high time-averaged enthalpy values were found to occur on the pressure side of the blades in the MP configuration.

Support pedestals for interconnecting a cover and nozzle band wall in a gas turbine nozzle segment

DOEpatents

Yu, Yufeng Phillip; Itzel, Gary Michael; Webbon, Waylon Willard; Bagepalli, Radhakrishna; Burdgick, Steven Sebastian; Kellock, Iain Robertson

2002-01-01

A gas turbine nozzle segment has outer and inner band portions. Each band portion includes a nozzle wall, a cover and an impingement plate between the cover and nozzle wall defining two cavities on opposite sides of the impingement plate. Cooling steam is supplied to one cavity for flow through the apertures of the impingement plate to cool the nozzle wall. Structural pedestals interconnect the cover and nozzle wall and pass through holes in the impingement plate to reduce localized stress otherwise resulting from a difference in pressure within the chamber of the nozzle segment and the hot gas path and the fixed turbine casing surrounding the nozzle stage. The pedestals may be cast or welded to the cover and nozzle wall.

Hip impingement: beyond femoroacetabular

PubMed Central

Bardakos, Nikolaos V.

2015-01-01

In the last 20 years, femoroacetabular impingement has been at the forefront of clinical practice as a cause of hip pain in young adults. As arthroscopic techniques for the hip continue to evolve, the possible presence of a new group of conditions creating mechanical conflict in and around the hip joint (ischiofemoral, subspine and iliopsoas impingement) has recently been elucidated whilst interest in already known ‘impingement’ syndromes (pelvic-trochanteric and pectineofoveal impingement) is now revived. This article attempts to increase awareness of these relatively uncommon clinical entities by describing their pathomorphology, contact mechanics, treatment and published results available to present. It is hoped that such knowledge will diversify therapeutic options for the clinician, thereby improving outcomes in a small but not negligible portion of patients with previously unexplained persistent symptoms. PMID:27011843

Advanced electric propulsion research - 1990

NASA Technical Reports Server (NTRS)

Monheiser, Jeffery M.; Wilbur, Paul J.

1991-01-01

An experimental study of impingement current collection on the accelerator grid of an ion thruster is presented. The equipment, instruments, and procedures being used to conduct the study are discussed. The contribution to this current due to charge-exchange ions produced close to the grid is determined using a volume-integration procedure and measured ion beam current design, computed neutral atom density and measured beam plasma potential data. This current, which is expected to be almost equal to that measured directly, is found to be an order of magnitude less. The impingement current determined by integrating the current density of ambient ions in the beam plasma close to the grid is found to agree with the directly measured impingement current. Possible reasons for the disagreement between the directly measured and volume integrated impingement currents are discussed.

TACT1- TRANSIENT THERMAL ANALYSIS OF A COOLED TURBINE BLADE OR VANE EQUIPPED WITH A COOLANT INSERT

NASA Technical Reports Server (NTRS)

Gaugler, R. E.

1994-01-01

As turbine-engine core operating conditions become more severe, designers must develop more effective means of cooling blades and vanes. In order to design reliable, cooled turbine blades, advanced transient thermal calculation techniques are required. The TACT1 computer program was developed to perform transient and steady-state heat-transfer and coolant-flow analyses for cooled blades, given the outside hot-gas boundary condition, the coolant inlet conditions, the geometry of the blade shell, and the cooling configuration. TACT1 can analyze turbine blades, or vanes, equipped with a central coolant-plenum insert from which coolant-air impinges on the inner surface of the blade shell. Coolant-side heat-transfer coefficients are calculated with the heat transfer mode at each station being user specified as either impingement with crossflow, forced convection channel flow, or forced convection over pin fins. A limited capability to handle film cooling is also available in the program. The TACT1 program solves for the blade temperature distribution using a transient energy equation for each node. The nodal energy balances are linearized, one-dimensional, heat-conduction equations which are applied at the wall-outer-surface node, at the junction of the cladding and the metal node, and at the wall-inner-surface node. At the mid-metal node a linear, three-dimensional, heat-conduction equation is used. Similarly, the coolant pressure distribution is determined by solving the set of transfer momentum equations for the one-dimensional flow between adjacent fluid nodes. In the coolant channel, energy and momentum equations for one-dimensional compressible flow, including friction and heat transfer, are used for the elemental channel length between two coolant nodes. The TACT1 program first obtains a steady-state solution using iterative calculations to obtain convergence of stable temperatures, pressures, coolant-flow split, and overall coolant mass balance. Transient calculations are based on the steady-state solutions obtained. Input to the TACT1 program includes a geometrical description of the blade and insert, the nodal spacing to be used, and the boundary conditions describing the outside hot-gas and the coolant-inlet conditions. The program output includes the value of nodal temperatures and pressures at each iteration. The final solution output includes the temperature at each coolant node, and the coolant flow rates and Reynolds numbers. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 360 computer with a central memory requirement of approximately 480K of 8 bit bytes. The TACT1 program was developed in 1978.

Direct observation of spatially isothermal equiaxed solidification of an Al-Cu alloy in microgravity on board the MASER 13 sounding rocket

NASA Astrophysics Data System (ADS)

Murphy, A. G.; Mathiesen, R. H.; Houltz, Y.; Li, J.; Lockowandt, C.; Henriksson, K.; Melville, N.; Browne, D. J.

2016-11-01

For the first time, isothermal equiaxed solidification of a metallic alloy has been observed in situ in space, providing unique benchmark experimental data. The experiment was completed on board the MASER 13 sounding rocket, launched in December 2015, using a newly developed isothermal solidification furnace. A grain-refined Al-20 wt%Cu sample was fully melted and solidified during 360 s of microgravity and the solidification sequence was recorded using time-resolved X-radiography. Equiaxed nucleation, dendritic growth, solutal impingement, and eutectic transformation were thus observed in a gravity-free environment. Equiaxed nucleation was promoted through application of a controlled cooling rate of -0.05 K/s producing a 1D grain density of 6.5 mm-1, uniformly distributed throughout the field of view (FOV). Primary growth slowed to a visually imperceptible level at an estimated undercooling of 7 K, after which the cooling rate was increased to -1.0 K/s for the remainder of solidification and eutectic transformation, ensuring the sample was fully solidified inside the microgravity time window. The eutectic transformation commenced at the centre of the FOV proceeding radially outwards covering the entire FOV in 3 s Microgravity-based solidification is compared to an identical pre-flight ground-based experiment using the same sample and experiment timeline. The ground experiment was designed to minimise gravity effects, by choice of a horizontal orientation for the sample, so that any differences would be subtle. The first equiaxed nucleation occurred at an apparent undercooling of 0.6 K less than the equivalent event during microgravity. During primary equiaxed solidification, as expected, no buoyant grain motion was observed during microgravity, compared to modest grain rotation and reorientation observed during terrestrial-based solidification. However, when the cooling rate was increased from -0.05 K/s to -1.0 K/s during the latter stages of solidification, in both 1g and micro-g environments, some grain movement was apparent due to liquid feeding and mechanical impingement of neighbouring grains.

α-Phase transformation kinetics of U – 8 wt% Mo established by in situ neutron diffraction

DOE PAGES

Garlea, Elena; Steiner, M. A.; Calhoun, C. A.; ...

2016-05-08

The α-phase transformation kinetics of as-cast U - 8 wt% Mo below the eutectoid temperature have been established by in situ neutron diffraction. α-phase weight fraction data acquired through Rietveld refinement at five different isothermal hold temperatures can be modeled accurately utilizing a simple Johnson-Mehl-Avrami-Kolmogorov impingement-based theory, and the results are validated by a corresponding evolution in the γ-phase lattice parameter during transformation that follows Vegard’s law. Neutron diffraction data is used to produce a detailed Time-Temperature-Transformation diagram that improves upon inconsistencies in the current literature, exhibiting a minimum transformation start time of 40 min at temperatures between 500 °Cmore » and 510 °C. Lastly, the transformation kinetics of U – 8 wt% Mo can vary significantly from as-cast conditions after extensive heat treatments, due to homogenization of the typical dendritic microstructure which possesses non-negligible solute segregation.« less

Current developments and tests of small x-ray optical systems for space applications

NASA Astrophysics Data System (ADS)

Pina, L.; Hudec, R.; Inneman, A.; Doubravová, D.; Marsikova, V.

2017-05-01

The paper addresses the X-ray monitoring for astrophysical applications. A novel approach based on the use of 1D and 2D "Lobster eye" optics in combination with Timepix X-ray detector in the energy range 3 - 40 keV was further studied. Wide-field optical system of this type has not been used in space yet. Designed wide-field optical system combined with Timepix X-ray detector is described together with latest experimental results obtained during laboratory tests. Proposed project includes theoretical study and a functional sample of the Timepix X-ray detector with multifoil wide-field X-ray "Lobster eye" optics. Using optics to focus X-rays on a detector is the only solution in cases where intensity of impinging X-ray radiation is below the sensitivity of the detector, e.g. while monitoring astrophysical objects in space, or phenomena in the Earth's atmosphere. The optical system is considered to be used in a student rocket experiment.

Wavelet-based analysis of transient electromagnetic wave propagation in photonic crystals.

PubMed

Shifman, Yair; Leviatan, Yehuda

2004-03-01

Photonic crystals and optical bandgap structures, which facilitate high-precision control of electromagnetic-field propagation, are gaining ever-increasing attention in both scientific and commercial applications. One common photonic device is the distributed Bragg reflector (DBR), which exhibits high reflectivity at certain frequencies. Analysis of the transient interaction of an electromagnetic pulse with such a device can be formulated in terms of the time-domain volume integral equation and, in turn, solved numerically with the method of moments. Owing to the frequency-dependent reflectivity of such devices, the extent of field penetration into deep layers of the device will be different depending on the frequency content of the impinging pulse. We show how this phenomenon can be exploited to reduce the number of basis functions needed for the solution. To this end, we use spatiotemporal wavelet basis functions, which possess the multiresolution property in both spatial and temporal domains. To select the dominant functions in the solution, we use an iterative impedance matrix compression (IMC) procedure, which gradually constructs and solves a compressed version of the matrix equation until the desired degree of accuracy has been achieved. Results show that when the electromagnetic pulse is reflected, the transient IMC omits basis functions defined over the last layers of the DBR, as anticipated.

Electromagnetic Control of High Heat-Flux Spray Impingement Boiling Under Microgravity Conditions

DTIC Science & Technology

2007-03-01

impingement boiling ( Mudawar , 2000; Chow et al., 1997; Tilton, 1989). With water as the working fluid, spray cooling has achieved a heat flux on the...Stebbins, C. J., and Mudawar , I., 1996. "Mapping of Impact and Heat Transfer Regimes of Water Drops Impinging on a Polished Surface," Int. J. Heat and Mass...34 Proceedings of SAE 2004 Power Systems Conference, 2004-01-3204, Reno NV, November, pp. 309-317. Mudawar , 1., 2000. "Assessment of High-heat Flux

Investigation of the Hazards Posed by Chemical Vapors Released in Marine Operations - Phase II.

DTIC Science & Technology

1983-04-01

Methodology 4 IV.1 Nondimensional Radial Velocity Profiles Following Jet Impingement 30 IV.2 3.66m Cube Ventilation Test Tank Apparatus 44 IV.3 Test No. 19...available for product evaporation in the bays immediately beneath the * blower jet . The second modification would reflect the fact that bays that are... jet impingement model in Reference 8 to generate an ex- pression for Uwind* The model in Reference 8 was derived for the normal impinge- ment of a

OVERFLOW Validation for Predicting Plume Impingement of Underexpanded Axisymmetric Jets onto Angled Flat Plates

NASA Technical Reports Server (NTRS)

Lee, Henry C.; Klopfer, Goetz

2011-01-01

This report documents how OVERFLOW, a computational fluid dynamics code, predicts plume impingement of underexpanded axisymmetric jets onto both perpendicular and inclined flat plates. The effects of the plume impinging on a range of plate inclinations varying from 90deg to 30deg are investigated and compared to the experimental results in Reference 1 and 2. The flow fields are extremely complex due to the interaction between the shock waves from the free jet and those deflected by the plate. Additionally, complex mixing effects create very intricate structures in the flow. The experimental data is very limited, so these validation studies will focus only on cold plume impingement on flat and inclined plates. This validation study will help quantify the error in the OVERFLOW simulation when applied to stage separation scenarios.

Arthroscopic Resection of a Large Bony Exostosis Arising from the Anterior Inferior Iliac Spine Causing Extra-articular Hip Impingement: A Case Series

PubMed Central

Carton, Patrick; Filan, David

2016-01-01

Introduction: Abnormal morphology of the anterior inferior iliac spine (AIIS) is a rarely recognized but important source of extra-articular hip impingement. Chronic progressive symptoms of stiffness and limitation of hip motion with persistent groin pain may place significant restriction on activity. Concomitant femoroacetabular impingement is often present but recognition and effective treatment of the uncommon extra-articular component is important for successful outcome. Case Report: Three cases of symptomatic extra-articular hip impingement secondary to AIIS deformity and in conjunction with mild underlying femoroacetabular impingement (FAI) are presented. They include two athletic Caucasian males aged 27 and 35-years old with a history of prior rectus tendon injury and secondary bony exostosis formation and a 53-year-old Caucasian male with a nontraumatic, developmental AIIS deformity. In all cases, an excellent clinical outcome with a full return to pain free activity was achieved postoperation. Their clinical presentation, diagnosis and post-operative outcome at 1.5-2 years (mean 1.7 years) following arthroscopic AIIS resection are discussed. Conclusion: Arthroscopic management of AIIS extra-articular hip impingement has been rarely reported and the longer-term outcome is unknown. We report the successful clinical outcome in a case series of three patients up to 2 years following arthroscopic AIIS resection. This case series demonstrates the sustainable benefits of arthroscopic correction of AIIS bony exostosis as a cause of extra-articular FAI. PMID:29537397

Arthroscopic treatment of patients with anterolateral impingement of the ankle with and without chondral lesions.

PubMed

Mardani-Kivi, Mohsen; Mirbolook, Ahmadreza; Khajeh-Jahromi, Sina; Hassanzadeh, Rasool; Hashemi-Motlagh, Keyvan; Saheb-Ekhtiari, Khashayar

2013-01-01

Anterolateral impingement syndrome is defined as chronic pain in the ankle secondary to soft tissue impingement, hypertrophy, or tearing of the lateral and anterolateral ligaments of the ankle. The purpose of the present study was to evaluate the results of arthroscopic treatment of anterolateral impingement syndrome and its association with chondral lesions. In this case series study, 23 patients with anterolateral impingement syndrome underwent arthroscopic debridement of the ankle. Simple radiography and magnetic resonance imaging were applied for all the patients to diagnose the spur condition and to exclude patients with other possible lesions. All the patients were evaluated preoperatively and at interval visits of 2, 4, and 6 weeks and 3 and 6 months postoperatively according to the American Orthopaedic Foot and Ankle Society criteria and Meislin score. The mean patient age was 38.13 ± 6.85 years. Significant differences were seen between the mean American Orthopaedic Foot and Ankle Society scores, which was 59.21 before surgery and 83.56 and 88.13 at 3 and 6 months postoperatively, respectively. No significant differences were seen between the American Orthopaedic Foot and Ankle Society scores of the patients with or without chondral lesions. Arthroscopic treatment of anterolateral impingement syndrome is recommended as the treatment of choice and is still considerably effective in patients with chondral lesions. Copyright © 2013 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Sports-Based Text Sets: Fostering Critical Literacy at the Intersections of Sport and Society

ERIC Educational Resources Information Center

Rodesiler, Luke

2017-01-01

Sports culture is central to the lives of many students, whether they participate in athletic competitions or sports fandom. Unfortunately, sports culture also reflects many sociopolitical issues and inequities that impinge upon our greater society in the present day (e.g., domestic violence, racism). For those reasons, sports-based text…

The Aerodynamic and Dynamic Loading of a Slender Structure by an Impacting Tornado-Like Vortex: The Influence of Relative Vortex-to-Structure Size on Structural Loading

NASA Astrophysics Data System (ADS)

Strasser, Matthew N.

Structural loading produced by an impacting vortex is a hazardous phenomenon that is encountered in numerous applications ranging from the destruction of residences by tornados to the chopping of tip vortices by rotors. Adequate design of structures to resist vortex-induced structural loading necessitates study of the phenomenon that control the structural loading produced by an impacting vortex. This body of work extends the current knowledge base of vortex-structure interaction by evaluating the influence of the relative vortex-to-structure size on the structural loading that the vortex produces. A computer model is utilized to directly simulate the two-dimensional impact of an impinging vortex with a slender, cylindrical structure. The vortex's tangential velocity profile (TVP) is defined by a normalization of the Vatistas analytical (TVP) which realistically replicates the documented spectrum of measured vortex TVPs. The impinging vortex's maximum tangential velocity is fixed, and the vortex's critical radius is incremented from one to one-hundred times the structure's diameter. When the impinging vortex is small, it interacts with vortices produced on the structure by the free stream, and maximum force coefficient amplitudes vary by more than 400% when the impinging vortex impacts the structure at different times. Maximum drag and lift force coefficient amplitudes reach asymptotic values as the impinging vortex's size increases that are respectively 94.77% and 10.66% less than maximum force coefficients produced by an equivalent maximum velocity free stream. The vortex produces maximum structural loading when its path is shifted above the structure's centerline, and maximum drag and lift force coefficients are respectively up to 4.80% and 34.07% greater than maximum force coefficients produced by an equivalent-velocity free stream. Finally, the dynamic load factor (DLF) concept is used to develop a generalized methodology to assess the dynamic amplification of a structure's response to vortex loading and to assess the dynamic loading threat that tornados pose. Typical civil and residential structures will not experience significant response amplification, but responses of very flexible structures may be amplified by up to 2.88 times.

Measurements of Two-Phase Suspended Sediment Transport in Breaking Waves Using Volumetric Three-Component Velocimetry

NASA Astrophysics Data System (ADS)

Ting, F. C. K.; LeClaire, P.

2016-02-01

Understanding the mechanisms of sediment pickup and distribution in breaking waves is important for modeling sediment transport in the surf zone. Previous studies were mostly concerned with bulk sediment transport under specific wave conditions. The distribution of suspended sediments in breaking waves had not been measured together with coherent flow structures. In this study, two-phase flow measurements were obtained under a train of plunging regular waves on a plane slope using the volumetric three-component velocimetry (V3V) technique. The measurements captured the motions of sediment particles simultaneously with the three-component, three-dimensional (3C3D) velocity fields of turbulent coherent structures (large eddies) induced by breaking waves. Sediment particles (solid glass spheres diameter 0.125 to 0.15 mm, specific gravity 2.5) were separated from fluid tracers (mean diameter 13 µm, specific gravity 1.3) based on a combination of particle spot size and brightness in the two-phase images. The interactions between the large eddies and glass spheres were investigated for plunger vortices generated at incipient breaking and for splash-up vortices generated at the second plunge point. The measured data show that large eddies impinging on the bottom was the primary mechanism which lift sediment particles into suspension and momentarily increased near-bed suspended sediment concentration. Although eddy impingement events were sporadic in space and time, the distributions of suspended sediments in the large eddies were not uniform. High suspended sediment concentration and vertical sediment flux were found in the wall-jet region where the impinging flow was deflected outward and upward. Sediment particles were also trapped and carried around by counter-rotating vortices (Figure 1). Suspended sediment concentration was significantly lower in the impingement region where the fluid velocity was downward, even though turbulent kinetic energy in the down flow was very high. These results suggest that vertical velocity or turbulent shear stress may be a better parameter for predicting sediment pick-up rate than turbulent kinetic energy. It was also found that splash-up vortices enhanced onshore transport relative to the condition when no vortex impinged on the bottom.

Combustion of LOX with H2(sub g) under subcritical, critical, and supercritical conditions and experimental observation of dense spray and mixing of impinging jets

NASA Technical Reports Server (NTRS)

Kuo, Kenneth K.; Hsieh, W. H.; Yang, A. S.; Brown, J. J.; Cheung, F. B.; Woodward, R. D.; Kline, M. C.

1992-01-01

Progress made during the period of February 1 to October 15, 1992 is reported. The overall objective of Task 1 of the investigation is to achieve a better understanding of the combustion processes of liquid oxygen and gaseous hydrogen under subcritical, critical, and supercritical conditions. Specific objectives of the research program are: (1) to determine the evaporation- and burning-rate characteristics of LOX in hydrogen/helium environments under broad ranges of operating conditions; (2) to measure species concentration profile and surface temperature of LOX employing the gas chromatography and fine-wire thermocouples under non-reacting flow situations; (3) to perform a fugacity-based multicomponent thermodynamic phase equilibrium analysis for examining the high-pressure vapor-liquid equilibrium behavior at the liquid surface of LOX; (4) to formulate and solve a theoretical model for simulating the evaporation and combustion processes in a LOX/H2/He system; and (5) to validate the theoretical model with the measured experimental data. Task 2 of the investigation is described. Observation of a like-on-like injector element in the near-injector region performed in the previous phase of this project has identified the existence of a high Reynolds number regime in which the pre-impingement jets are fully turbulent and undergoing surface breakup. The new spray regime, which has not been observed by previous investigators, is characterized by the presence of many fine droplets and the disappearance of the well-defined liquid breakup wave pattern in the post-impingement region. It is speculated that a cavitating region may be present within the orifice so that it could induce strong turbulence, leading to an onset of atomization of the jets prior to impingement. To further investigate the dense spray behavior of the impinging jets in the high Reynolds number region, experiments were conducted using Plexiglas injector components for direct internal flow observation. The main objective is to determine under what conditions a cavitating region would form and whether or not the cavitation is reponsible for the development of the high Reynolds number spray regime. The procedure and major findings of the injector cavitation study are described.

Comparison of Orbiter PRCS Plume Flow Fields Using CFD and Modified Source Flow Codes

NASA Technical Reports Server (NTRS)

Rochelle, Wm. C.; Kinsey, Robin E.; Reid, Ethan A.; Stuart, Phillip C.; Lumpkin, Forrest E.

1997-01-01

The Space Shuttle Orbiter will use Reaction Control System (RCS) jets for docking with the planned International Space Station (ISS). During approach and backout maneuvers, plumes from these jets could cause high pressure, heating, and thermal loads on ISS components. The object of this paper is to present comparisons of RCS plume flow fields used to calculate these ISS environments. Because of the complexities of 3-D plumes with variable scarf-angle and multi-jet combinations, NASA/JSC developed a plume flow-field methodology for all of these Orbiter jets. The RCS Plume Model (RPM), which includes effects of scarfed nozzles and dual jets, was developed as a modified source-flow engineering tool to rapidly generate plume properties and impingement environments on ISS components. This paper presents flow-field properties from four PRCS jets: F3U low scarf-angle single jet, F3F high scarf-angle single jet, DTU zero scarf-angle dual jet, and F1F/F2F high scarf-angle dual jet. The RPM results compared well with plume flow fields using four CFD programs: General Aerodynamic Simulation Program (GASP), Cartesian (CART), Unified Solution Algorithm (USA), and Reacting and Multi-phase Program (RAMP). Good comparisons of predicted pressures are shown with STS 64 Shuttle Plume Impingement Flight Experiment (SPIFEX) data.

Continuous preparation of nanoscale zero-valent iron using impinging stream-rotating packed bed reactor and their application in reduction of nitrobenzene

NASA Astrophysics Data System (ADS)

Jiao, Weizhou; Qin, Yuejiao; Luo, Shuai; Feng, Zhirong; Liu, Youzhi

2017-02-01

Nanoscale zero-valent iron (nZVI) was continuously prepared by high-gravity reaction precipitation through a novel impinging stream-rotating packed bed (IS-RPB). Reactant solutions of FeSO4 and NaBH4 were conducted into the IS-RPB with flow rates of 60 L/h and rotating speed of 1000 r/min for the preparation of nZVI. As-prepared nZVI obtained by IS-RPB were quasi-spherical morphology and almost uniformly distributed with a particle size of 10-20 nm. The reactivity of nZVI was estimated by the degradation of 100 ml nitrobenzene (NB) with initial concentration of 250 mg/L. The optimum dosage of nZVI obtained by IS-RPB was 4.0 g/L as the NB could be completely removed within 10 min, which reduced 20% compared with nZVI obtained by stirred tank reactor (STR). The reduction of NB and production of aniline (AN) followed pseudo-first-order kinetics, and the pseudo-first-order rate constants were 0.0147 and 0.0034 s-1, respectively. Furthermore, the as-prepared nZVI using IS-RPB reactor in this work can be used within a relatively wide range pH of 1-9.

Chemical and physical pretreatments of fruits and vegetables: Effects on drying characteristics and quality attributes - a comprehensive review.

PubMed

Deng, Li-Zhen; Mujumdar, Arun S; Zhang, Qian; Yang, Xu-Hai; Wang, Jun; Zheng, Zhi-An; Gao, Zhen-Jiang; Xiao, Hong-Wei

2017-12-20

Pretreatment is widely used before drying of agro-products to inactivate enzymes, enhance drying process and improve quality of dried products. In current work, the influence of various pretreatments on drying characteristics and quality attributes of fruits and vegetables is summarized. They include chemical solution (hyperosmotic, alkali, sulfite and acid, etc.) and gas (sulfur dioxide, carbon dioxide and ozone) treatments, thermal blanching (hot water, steam, super heated steam impingement, ohmic and microwave heating, etc), and non-thermal process (ultrasound, freezing, pulsed electric field, and high hydrostatic pressure, etc). Chemical pretreatments effectively enhance drying kinetics, meanwhile, it causes soluble nutrients losing, trigger food safety issues by chemical residual. Conventional hot water blanching has significant effect on inactivating various undesirable enzymatic reactions, destroying microorganisms, and softening the texture, as well as facilitating drying rate. However, it induces undesirable quality of products, e.g., loss of texture, soluble nutrients, pigment and aroma. Novel blanching treatments, such as high-humidity hot air impingement blanching, microwave and ohmic heat blanching can reduce the nutrition loss and are more efficient. Non-thermal technologies can be a better alternative to thermal blanching to overcome these drawbacks, and more fundamental researches are needed for better design and scale up.

Simulation of Flow Through Breach in Leading Edge at Mach 24

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.; Alter, Stephen J.

2004-01-01

A baseline solution for CFD Point 1 (Mach 24) in the STS-107 accident investigation was modified to include effects of holes through the leading edge into a vented cavity. The simulations were generated relatively quickly and early in the investigation by making simplifications to the leading edge cavity geometry. These simplifications in the breach simulations enabled: 1) A very quick grid generation procedure; 2) High fidelity corroboration of jet physics with internal surface impingements ensuing from a breach through the leading edge, fully coupled to the external shock layer flow at flight conditions. These simulations provided early evidence that the flow through a 2 inch diameter (or larger) breach enters the cavity with significant retention of external flow directionality. A normal jet directed into the cavity was not an appropriate model for these conditions at CFD Point 1 (Mach 24). The breach diameters were of the same order or larger than the local, external boundary-layer thickness. High impingement heating and pressures on the downstream lip of the breach were computed. It is likely that hole shape would evolve as a slot cut in the direction of the external streamlines. In the case of the 6 inch diameter breach the boundary layer is fully ingested.

Wetting and spreading behaviors of impinging microdroplets on textured surfaces

NASA Astrophysics Data System (ADS)

Kwon, Dae Hee; Lee, Sang Joon; CenterBiofluid and Biomimic Reseach Team

2012-11-01

Textured surfaces having an array of microscale pillars have been receiving large attention because of their potential uses for robust superhydrophobic and superoleophobic surfaces. In many practical applications, the textured surfaces usually accompany impinging small-scale droplets. To better understand the impinging phenomena on the textured surfaces, the wetting and spreading behaviors of water microdroplets are investigated experimentally. Microdroplets with diameter less than 50 μm are ejected from a piezoelectric printhead with varying Weber number. The final wetting state of an impinging droplet can be estimated by comparing the wetting pressures of the droplet and the capillary pressure of the textured surface. The wetting behaviors obtained experimentally are well agreed with the estimated results. In addition, the transition from bouncing to non-bouncing behaviors in the partially penetrated wetting state is observed. This transition implies the possibility of withdrawal of the penetrated liquid from the inter-pillar space. The maximum spreading factors (ratio of the maximum spreading diameter to the initial diameter) of the impinging droplets have close correlation with the texture area fraction of the surfaces. This work was supported by Creative Research Initiatives (Diagnosis of Biofluid Flow Phenomena and Biomimic Research) of MEST/KOSEF.

Anterior Inferior Iliac Spine (AIIS) and Subspine Hip Impingement.

PubMed

Carton, Patrick; Filan, David

2016-01-01

Abnormal morphology of the anterior inferior iliac spine (AIIS) and the subspine region of the acetabular rim are increasingly being recognised as a source of symptomatic extra-articular hip impingement. This review article aims to highlight important differences in the pathogenesis, clinical presentation and management of extra-articular hip impingement from both the AIIS and subspine bony regions, and the outcome following surgical intervention. A literature review was undertaken to examine the supporting evidence for AIIS and subspine hip impingement. A narrative account of the Author's professional experience in this area, including operative technique for arthroscopic correction, is also presented. Abnormal morphology of the AIIS and subspine region has been classified using cadaveric, radiological and arthroscopic means; the clinical presentation and operative treatment has been documented in several case series studies. Dual pathology is often present - recognition and treatment of both intra- and extra-articular components are necessary for good postoperative outcome. AIIS and sub-spine hip impingement should be considered as distinct pathological entities, which may also co-exist. Symptom relief can be expected following arthroscopic deformity correction with the treatment of concomitant intra-articular pathology. Failure to recognise and treat the extra-articular component may affect postoperative outcome. V.

MRI evaluation of anterolateral soft tissue impingement of the ankle.

PubMed

Ferkel, Richard D; Tyorkin, Max; Applegate, Gregory R; Heinen, Gregory T

2010-08-01

The usefulness of magnetic resonance imaging (MRI) has been questioned in evaluating patients with chronic ankle sprain pain. The purpose of this study was to determine the effectiveness and reliability of routine MR imaging in the diagnosis of anterolateral soft tissue impingement. Inclusion criteria required that the MR examinations be performed by the same musculoskeletal radiologist after the most recent scanner upgrade and using a dedicated ankle/hindfoot coil. The surgical and MRI reports of 24 patients who had an arthroscopic diagnosis of anterolateral soft tissue impingement of the ankle were tabulated and categorized. Unlike previous studies, sagittal T1 and Short Tau Inversion Recovery (STIR) images were used primarily in the diagnosis of these lesions. Using this technique, we report a 78.9% accuracy in diagnosis, a sensitivity of 83.3% and a specificity of 78.6%. Fifty-eight percent of patients had an associated diagnosis, which in 33% of patients altered our surgical plan. Although not indicated in all cases of anterolateral ankle impingement, we advocate the use of MR imaging in complicated clinical presentations where the exclusion of additional pathology in the ankle or subtalar joint, and the confirmation of anterolateral soft tissue impingement would be beneficial.

Reduced atomic shadowing in HiPIMS: Role of the thermalized metal ions

NASA Astrophysics Data System (ADS)

Oliveira, João Carlos; Ferreira, Fábio; Anders, André; Cavaleiro, Albano

2018-03-01

In magnetron sputtering, the ability to tailor film properties depends primarily on the control of the flux of particles impinging on the growing film. Among deposition mechanisms, the shadowing effect leads to the formation of a rough surface and a porous, columnar microstructure. Re-sputtered species may be re-deposited in the valleys of the films surface and thereby contribute to a reduction of roughness and to fill the underdense regions. Both effects are non-local and they directly compete to shape the final properties of the deposited films. Additional control of the bombarding flux can be obtained by ionizing the sputtered flux, because ions can be controlled with respect to their energy and impinging direction, such as in High-Power Impulse Magnetron Sputtering (HiPIMS). In this work, the relation between ionization of the sputtered species and thin film properties is investigated in order to identify the mechanisms which effectively influence the shadowing effect in Deep Oscillation Magnetron Sputtering (DOMS), a variant of HiPIMS. The properties of two Cr films deposited using the same averaged target power by d.c. magnetron sputtering and DOMS have been compared. Additionally, the angle distribution of the Cr species impinging on the substrate was simulated using Monte Carlo-based programs while the energy distribution of the energetic particles bombarding the substrate was evaluated by energy-resolved mass analysis. It was found that the acceleration of the thermalized chromium ions at the substrate sheath in DOMS significantly reduces the high angle component of their impinging angle distribution and, thus, efficiently reduces atomic shadowing. Therefore, a high degree of ionization in HiPIMS results in almost shadowing effect-free film deposition and allows us to deposit dense and compact films without the need of high energy particle bombardment during growth.

Indicators of AEI applied to the Delaware Estuary.

PubMed

Barnthouse, Lawrence W; Heimbuch, Douglas G; Anthony, Vaughn C; Hilborn, Ray W; Myers, Ransom A

2002-05-18

We evaluated the impacts of entrainment and impingement at the Salem Generating Station on fish populations and communities in the Delaware Estuary. In the absence of an agreed-upon regulatory definition of "adverse environmental impact" (AEI), we developed three independent benchmarks of AEI based on observed or predicted changes that could threaten the sustainability of a population or the integrity of a community. Our benchmarks of AEI included: (1) disruption of the balanced indigenous community of fish in the vicinity of Salem (the "BIC" analysis); (2) a continued downward trend in the abundance of one or more susceptible fish species (the "Trends" analysis); and (3) occurrence of entrainment/impingement mortality sufficient, in combination with fishing mortality, to jeopardize the future sustainability of one or more populations (the "Stock Jeopardy" analysis). The BIC analysis utilized nearly 30 years of species presence/absence data collected in the immediate vicinity of Salem. The Trends analysis examined three independent data sets that document trends in the abundance of juvenile fish throughout the estuary over the past 20 years. The Stock Jeopardy analysis used two different assessment models to quantify potential long-term impacts of entrainment and impingement on susceptible fish populations. For one of these models, the compensatory capacities of the modeled species were quantified through meta-analysis of spawner-recruit data available for several hundred fish stocks. All three analyses indicated that the fish populations and communities of the Delaware Estuary are healthy and show no evidence of an adverse impact due to Salem. Although the specific models and analyses used at Salem are not applicable to every facility, we believe that a weight of evidence approach that evaluates multiple benchmarks of AEI using both retrospective and predictive methods is the best approach for assessing entrainment and impingement impacts at existing facilities.

A computational study of the flowfield surrounding the Aeroassist Flight Experiment vehicle

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.; Greene, Francis A.

1987-01-01

A symmetric total variation diminishing (STVD) algorithm has been applied to the solution of the three-dimensional hypersonic flowfield surrounding the Aeroassist Flight Experiment (AFE) vehicle. Both perfect-gas and chemical nonequilibrium models have been used. The perfect-gas flows were computed at two different Reynolds numbers, including a flight trajectory point at maximum dynamic pressure, and on two different grids. Procedures for coupling the solution of the species continuity equations with the Navier-Stokes equations in the presence of chemical nonequilibrium are reviewed and tested on the forebody of the AFE and on the complete flowfield assuming noncatalytic wall and no species diffusion. Problems with the STVD algorithm unique to flows with variable thermodynamic properties (real gas) are identified and algorithm modifications are suggested. A potential heating problem caused by strong flow impingement on the nozzle lip in the near wake at 0-deg angle of attack has been identified.

A Lagrangian parcel based mixing plane method for calculating water based mixed phase particle flows in turbo-machinery

NASA Astrophysics Data System (ADS)

Bidwell, Colin S.

2015-05-01

A method for calculating particle transport through turbo-machinery using the mixing plane analogy was developed and used to analyze the energy efficient engine . This method allows the prediction of temperature and phase change of water based particles along their path and the impingement efficiency and particle impact property data on various components in the engine. This methodology was incorporated into the LEWICE3D V3.5 software. The method was used to predict particle transport in the low pressure compressor of the . The was developed by NASA and GE in the early 1980s as a technology demonstrator and is representative of a modern high bypass turbofan engine. The flow field was calculated using the NASA Glenn ADPAC turbo-machinery flow solver. Computations were performed for a Mach 0.8 cruise condition at 11,887 m assuming a standard warm day for ice particle sizes of 5, 20 and 100 microns and a free stream particle concentration of . The impingement efficiency results showed that as particle size increased average impingement efficiencies and scoop factors increased for the various components. The particle analysis also showed that the amount of mass entering the inner core decreased with increased particle size because the larger particles were less able to negotiate the turn into the inner core due to particle inertia. The particle phase change analysis results showed that the larger particles warmed less as they were transported through the low pressure compressor. Only the smallest 5 micron particles were warmed enough to produce melting with a maximum average melting fraction of 0.18. The results also showed an appreciable amount of particle sublimation and evaporation for the 5 micron particles entering the engine core (22.6 %).

DSMC simulations of the Shuttle Plume Impingement Flight EXperiment(SPIFEX)

NASA Technical Reports Server (NTRS)

Stewart, Benedicte; Lumpkin, Forrest

2017-01-01

During orbital maneuvers and proximity operations, a spacecraft fires its thrusters inducing plume impingement loads, heating and contamination to itself and to any other nearby spacecraft. These thruster firings are generally modeled using a combination of Computational Fluid Dynamics (CFD) and DSMC simulations. The Shuttle Plume Impingement Flight EXperiment(SPIFEX) produced data that can be compared to a high fidelity simulation. Due to the size of the Shuttle thrusters this problem was too resource intensive to be solved with DSMC when the experiment flew in 1994.

Transition Research with Temperature-Sensitive Paints in the Boeing/AFOSR Mach-6 Quiet Tunnel

DTIC Science & Technology

2011-06-01

flow. This is because the presence of a model in the wind tunnel affects the flowfield due to the presence of a bow shock . This shock impinges on the...model, it was found that the bow shock reflected off the tunnel walls and impinged on the aft end of the model. Besides this region, when the model...reflected bow shock from impinging on the model. Transition occurred on the lee ray on the smaller model. Forward-facing and aft-facing steps on the model

Impact of Drift on the Vehicle Liftoff Acoustic Environments

NASA Technical Reports Server (NTRS)

Kenny, Jeremy; Giacomoni, Clothilde

2016-01-01

As a launch vehicle lifts off the pad, depending on the flyaway maneuver, it will drift away from the exhaust hole causing the plume(s) to impinge on the launch deck. This impingement on the deck creates acoustic sources and causes the noise levels on the vehicle to increase. The percentage of the plume which impinges on the deck can be calculated and related to sound pressure levels. Using this information, a delta dB can be calculated if the drift or flyaway maneuver for a specific vehicle changes during a program

Experimental Study of Supercooled Large Droplet Impingement Effects

NASA Technical Reports Server (NTRS)

Papadakis, M.; Rachman, A.; Wong, S. C.; Hung, K. E.; Vu, G. T.

2003-01-01

Typically, ice accretion results from small supercooled droplets (droplets cooled below freezing), usually 5 to 50 microns in diameter, which can freeze upon impact with an aircraft surface. Recently, ice accretions resulting from supercooled large droplet (SLD) conditions have become a safety concern. Current ice accretion codes have been extensively tested for Title 14 Code of Federal Regulations Part 25, Appendix C icing conditions but have not been validated for SLD icing conditions. This report presents experimental methods for investigating large droplet impingement dynamics and for obtaining small and large water droplet impingement data.

Ankle Impingement Caused by an Intra-articular Plica: A Report of 2 Cases.

PubMed

Rosenbaum, Andrew J; Positano, Rock G; Positano, Rock C J; Dines, Joshua S

2016-02-01

Entrapment of soft tissues in the anterolateral gutter of the ankle can cause impingement. When symptomatic, patients complain of chronic ankle pain exacerbated with dorsiflexion. Symptoms of instability and a history of recurring ankle sprains are common findings. Plain radiographs and magnetic resonance imaging may assist clinicians in identifying associated pathology. We present 2 cases of ankle impingement occurring in the setting of equivocal examination and imaging findings. In both cases, arthroscopy revealed a likely congenital, intra-articular plica. Therapeutic, Level IV: Case Study. © 2015 The Author(s).

Numerical insight into the micromechanics of jet erosion of a cohesive granular material

NASA Astrophysics Data System (ADS)

Cuéllar, Pablo; Benseghier, Zeyd; Luu, Li-Hua; Bonelli, Stéphane; Delenne, Jean-Yves; Radjaï, Farhang; Philippe, Pierre

2017-06-01

Here we investigate the physical mechanisms behind the surface erosion of a cohesive granular soil induced by an impinging jet by means of numerical simulations coupling fluid and grains at the microscale. The 2D numerical model combines the Discrete Element and Lattice Boltzmann methods (DEM-LBM) and accounts for the granular cohesion with a contact model featuring a paraboloidal yield surface. Here we review first the hydrodynamical conditions imposed by the fluid jet on a solid granular packing, turning then the attention to the impact of cohesion on the erosion kinetics. Finally, the use of an additional subcritical debonding damage model based on the work of Silvani and co-workers provides a novel insight into the internal solicitation of the cohesive granular sample by the impinging jet.

Numerical study of impact erosion of multiple solid particle

NASA Astrophysics Data System (ADS)

Zheng, Chao; Liu, Yonghong; Chen, Cheng; Qin, Jie; Ji, Renjie; Cai, Baoping

2017-11-01

Material erosion caused by continuous particle impingement during hydraulic fracturing results in significant economic loss and increased production risks. The erosion process is complex and has not been clearly explained through physical experiments. To address this problem, a multiple particle model in a 3D configuration was proposed to investigate the dynamic erosion process. This approach can significantly reduce experiment costs. The numerical model considered material damping and elastic-plastic material behavior of target material. The effects of impact parameters on erosion characteristics, such as plastic deformation, contact time, and energy loss rate, were investigated. Based on comprehensive studies, the dynamic erosion mechanism and geometry evolution of eroded crater was obtained. These findings can provide a detailed erosion process of target material and insights into the material erosion caused by multiple particle impingement.

Key technique study and application of infrared thermography in hypersonic wind tunnel

NASA Astrophysics Data System (ADS)

LI, Ming; Yang, Yan-guang; Li, Zhi-hui; Zhu, Zhi-wei; Zhou, Jia-sui

2014-11-01

The solutions to some key techniques using infrared thermographic technique in hypersonic wind tunnel, such as temperature measurement under great measurement angle, the corresponding relation between model spatial coordinates and the ones in infrared map, the measurement uncertainty analysis of the test data etc., are studied. The typical results in the hypersonic wind tunnel test are presented, including the comparison of the transfer rates on a thin skin flat plate model with a wedge measured with infrared thermography and thermocouple, the experimental study heating effect on the flat plate model impinged by plume flow and the aerodynamic heating on the lift model.

Geometrical-optics solution to light scattering by droxtal ice crystals.

PubMed

Zhang, Zhibo; Yang, Ping; Kattawar, George W; Tsay, Si-Chee; Baum, Bryan A; Hu, Yongxiang; Heymsfield, Andrew J; Reichardt, Jens

2004-04-20

We investigate the phase matrices of droxtals at wavelengths of 0.66 and 11 microm by using an improved geometrical-optics method. An efficient method is developed to specify the incident rays and the corresponding impinging points on the particle surface necessary to initialize the ray-tracing computations. At the 0.66-microm wavelength, the optical properties of droxtals are different from those of hexagonal ice crystals. At the 11-microm wavelength, the phase functions for droxtals are essentially featureless because of strong absorption within the particles, except for ripple structures that are caused by the phase interference of the diffracted wave.

Extra-articular hip impingement: a systematic review examining operative treatment of psoas, subspine, ischiofemoral, and greater trochanteric/pelvic impingement.

PubMed

de Sa, Darren; Alradwan, Hussain; Cargnelli, Stephanie; Thawer, Zoyah; Simunovic, Nicole; Cadet, Edwin; Bonin, Nicolas; Larson, Christopher; Ayeni, Olufemi R

2014-08-01

Extra-articular hip impingement can be the result of psoas impingement (PI), subspine impingement (SSI), ischiofemoral impingement (IFI), and greater trochanteric/pelvic impingement (GTPI). Symptoms may be due to bony abutment or soft-tissue irritation, and often, it is a challenge to differentiate among symptoms preoperatively. Currently, the clinical picture and diagnostic criteria are still being refined for these conditions. This systematic review was conducted to examine each condition and elucidate the indications for, treatment options for, and clinical outcomes of surgical management. We searched online databases (Medline, Embase, and PubMed) for English-language clinical studies published from database inception through December 31, 2013, addressing the surgical treatment of PI, SSI, IFI, and GTPI. For each condition, 2 independent assessors reviewed eligible studies. Descriptive statistics are presented. Overall, 9,521 studies were initially retrieved; ultimately, 14 studies were included examining 333 hips. For PI, arthroscopic surgery resulted in 88% of patients achieving good to excellent results, as well as significant improvements in the Harris Hip Score (P = .008), Hip Outcome Score-Activities of Daily Living (P = .02), and Hip Outcome Score-Sport (P = .04). For SSI, arthroscopic decompression, with no major complications, resulted in a mean 18.5° improvement in flexion range of motion, as well as improvements in pain (mean visual analog scale score of 5.9 points preoperatively and 1.2 points postoperatively) and the modified Harris Hip Score (mean of 64.97 points preoperatively and 91.3 points postoperatively). For both IFI and GTPI, open procedures anecdotally improved patient symptoms, with no formal objective outcomes data reported. This review suggests that there is some evidence to support that surgical treatment, by arthroscopy for PI and SSI and by open surgery for IFI and GTPI, results in improved patient outcomes. Systematic review of Level IV and V (case report) studies. Copyright © 2014 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Low altitude plume impingement handbook

NASA Technical Reports Server (NTRS)

Smith, Sheldon D.

1991-01-01

Plume Impingement modeling is required whenever an object immersed in a rocket exhaust plume must survive or remain undamaged within specified limits, due to thermal and pressure environments induced by the plume. At high altitudes inviscid plume models, Monte Carlo techniques along with the Plume Impingement Program can be used to predict reasonably accurate environments since there are usually no strong flowfield/body interactions or atmospheric effects. However, at low altitudes there is plume-atmospheric mixing and potential large flowfield perturbations due to plume-structure interaction. If the impinged surface is large relative to the flowfield and the flowfield is supersonic, the shock near the surface can stand off the surface several exit radii. This results in an effective total pressure that is higher than that which exists in the free plume at the surface. Additionally, in two phase plumes, there can be strong particle-gas interaction in the flowfield immediately ahead of the surface. To date there have been three levels of sophistication that have been used for low altitude plume induced environment predictions. Level 1 calculations rely on empirical characterizations of the flowfield and relatively simple impingement modeling. An example of this technique is described by Piesik. A Level 2 approach consists of characterizing the viscous plume using the SPF/2 code or RAMP2/LAMP and using the Plume Impingement Program to predict the environments. A Level 3 analysis would consist of using a Navier-Stokes code such as the FDNS code to model the flowfield and structure during a single calculation. To date, Level 1 and Level 2 type analyses have been primarily used to perform environment calculations. The recent advances in CFD modeling and computer resources allow Level 2 type analysis to be used for final design studies. Following some background on low altitude impingement, Level 1, 2, and 3 type analysis will be described.

Microtextured Surfaces for Turbine Blade Impingement Cooling

NASA Technical Reports Server (NTRS)

Fryer, Jack

2014-01-01

Gas turbine engine technology is constantly challenged to operate at higher combustor outlet temperatures. In a modern gas turbine engine, these temperatures can exceed the blade and disk material limits by 600 F or more, necessitating both internal and film cooling schemes in addition to the use of thermal barrier coatings. Internal convective cooling is inadequate in many blade locations, and both internal and film cooling approaches can lead to significant performance penalties in the engine. Micro Cooling Concepts, Inc., has developed a turbine blade cooling concept that provides enhanced internal impingement cooling effectiveness via the use of microstructured impingement surfaces. These surfaces significantly increase the cooling capability of the impinging flow, as compared to a conventional untextured surface. This approach can be combined with microchannel cooling and external film cooling to tailor the cooling capability per the external heating profile. The cooling system then can be optimized to minimize impact on engine performance.

[Cost-effectiveness of local steroid combined with therapeutic exercise in subacromial impingement syndrome].

PubMed

Ramírez-Ortiz, Julio; Mendoza-Eufracio, José Dolores; García-Viveros, María Ricarda; Márquez-Celedonio, Félix Guillermo

2017-01-01

The most common cause of injury is shoulder impingement syndrome. Management includes physical therapy, analgesics, steroids and surgery. The aim of the study was to determine the cost-effectiveness of using steroids combined with therapeutic exercise at home in the chronic impingement syndrome. Clinical trial randomized in 30 people with subacromial impingement syndrome underwent two treatments: steroid and at home rehabilitation booklet evaluated at the first and fourth week through UCLA Shoulder rating scale. We studied 17 men (56.7 %) and 13 women (43.3 %), mean age was 42.87 years. Group 2 earned greater improvement in UCLA Shoulder rating scale 18.87 at baseline and 27.60 at the end. With 30.27 accumulated disability days for group 1, and 14.80 for group 2. The combination of local steroids with therapeutic exercise is more effective clinically and declining disability compared to conventional physical therapy.

Apparatus for impingement cooling a side wall adjacent an undercut region of a turbine nozzle segment

DOEpatents

Burdgick, Steven Sebastian

2002-01-01

A gas turbine nozzle segment has outer and inner bands and vanes therebetween. Each band includes a side wall, a cover and an impingement plate between the cover and nozzle wall defining two cavities on opposite sides of the impingement plate. Cooling steam is supplied to one cavity for flow through apertures of the impingement plate to cool the nozzle wall. The side wall of the band and inturned flange define with the nozzle wall an undercut region. Slots are formed through the inturned flange along the nozzle side wall. A plate having through-apertures extending between opposite edges thereof is disposed in each slot, the slots and plates being angled such that the cooling medium exiting the apertures in the second cavity lie close to the side wall for focusing and targeting cooling medium onto the side wall.

An improved heat transfer configuration for a solid-core nuclear thermal rocket engine

NASA Technical Reports Server (NTRS)

Clark, John S.; Walton, James T.; Mcguire, Melissa L.

1992-01-01

Interrupted flow, impingement cooling, and axial power distribution are employed to enhance the heat-transfer configuration of a solid-core nuclear thermal rocket engine. Impingement cooling is introduced to increase the local heat-transfer coefficients between the reactor material and the coolants. Increased fuel loading is used at the inlet end of the reactor to enhance heat-transfer capability where the temperature differences are the greatest. A thermal-hydraulics computer program for an unfueled NERVA reactor core is employed to analyze the proposed configuration with attention given to uniform fuel loading, number of channels through the impingement wafers, fuel-element length, mass-flow rate, and wafer gap. The impingement wafer concept (IWC) is shown to have heat-transfer characteristics that are better than those of the NERVA-derived reactor at 2500 K. The IWC concept is argued to be an effective heat-transfer configuration for solid-core nuclear thermal rocket engines.

Improved Stirling engine performance using jet impingement

NASA Technical Reports Server (NTRS)

Johnson, D. C.; Britt, E. J.; Thieme, L. G.

1982-01-01

Of the many factors influencing the performance of a Stirling engine, that of transferring the combustion gas heat into the working fluid is crucial. By utilizing the high heat transfer rates obtainable with a jet impingement heat transfer system, it is possible to reduce the flame temperature required for engine operation. Also, the required amount of heater tube surface area may be reduced, resulting in a decrease in the engine nonswept volume and a related increase in engine efficiency. A jet impingement heat transfer system was designed by Rasor Associates, Inc., and tested in the GPU-3 Stirling engine at the NASA Lewis Research Center. For a small penalty in pumping power (less than 0.5% of engine output) the jet impingement heat transfer system provided a higher combustion-gas-side heat transfer coefficient and a smoothing of heater temperature profiles resulting in lower combustion system temperatures and a 5 to 8% increase in engine power output and efficiency.

Apollo Video Photogrammetry Estimation of Plume Impingement Effects

NASA Technical Reports Server (NTRS)

Immer, Christopher; Lane, John; Metzger, Philip; Clements, Sandra

2008-01-01

Each of the six Apollo mission landers touched down at unique sites on the lunar surface. Aside from the Apollo 12 landing site located 180 meters from the Surveyor III lander, plume impingement effects on ground hardware during the landings were largely not an issue. The Constellation Project's planned return to the moon requires numerous landings at the same site. Since the top few centimeters are loosely packed regolith, plume impingement from the lander ejects the granular material at high velocities. With high vacuum conditions on the moon (10 (exp -14) to 10 (epx -12) torr), motion of all particles is completely ballistic. Estimates from damage to the Surveyor III show that the ejected regolith particles to be anywhere 400 m/s to 2500 m/s. It is imperative to understand the physics of plume impingement to safely design landing sites for the Constellation Program.

Two or more impingement and/or instability deformities are often present in patients with hip pain.

PubMed

Tibor, Lisa M; Liebert, Gunnar; Sutter, Reto; Impellizzeri, Franco M; Leunig, Michael

2013-12-01

Damage to the hip can occur due to impingement or instability caused by anatomic factors such as femoral and acetabular version, neck-shaft angle, alpha angle, and lateral center-edge angle (CEA). The associations between these anatomic factors and how often they occur in a painful hip are unclear but if unaddressed might explain failed hip preservation surgery. We determined (1) the influence of sex on the expression of impingement-related or instability-related factors, (2) the associations among these factors, and (3) how often both impingement and/or instability factors occur in the same hip. We retrospectively reviewed a cohort of 170 hips (145 patients) undergoing MR arthrography of the hip for any reason. We excluded 58 hips with high-grade dysplasia, Perthes' sequelae, previous surgery, or incomplete radiographic information, leaving 112 hips (96 patients). We measured femoral version and alpha angles on MR arthrograms. Acetabular anteversion, lateral CEA, and neck-shaft angle were measured on pelvic radiographs. We observed a correlation between sex and alpha angle. Weak or no correlations were observed between the other five parameters. In 66% of hips, two or more (of five) impingement parameters, and in 51% of hips, two or more (of five) instability parameters were found. Patients with hip pain frequently have several anatomic factors potentially contributing to chondrolabral damage. To address pathologic hip loading due to impingement and/or instability, all of the anatomic influences should be known. As we found no associations between anatomic factors, we recommend an individualized assessment of each painful hip.

Scapular Notching on Kinematic Simulated Range of Motion After Reverse Shoulder Arthroplasty Is Not the Result of Impingement in Adduction

PubMed Central

Lädermann, Alexandre; Gueorguiev, Boyko; Charbonnier, Caecilia; Stimec, Bojan V.; Fasel, Jean H.D.; Zderic, Ivan; Hagen, Jennifer; Walch, Gilles

2015-01-01

Abstract Impingement after reverse shoulder arthroplasty (RSA) is believed to occur from repetitive contact in adduction between the humeral component and the inferior scapular pillar. The primary purpose of this biomechanical study was to confirm the presence of different types of impingement and to examine which daily-life movements are responsible for them. A secondary aim was to provide recommendations on the type of components that would best minimize notching and loss of range of motion (ROM). The study included 12 fresh frozen shoulder specimens; each had a computed tomography (CT) image of the entire scapula and humerus in order to acquire topological information of the bones before RSA implantation. Cyclic tests were run postimplantation with 3 shoulders in each modalities. To quantify bone loss due to impingement, 3-dimensional anatomical models of the scapula were reconstructed from the CT scans and compared to their intact states. We found 8 bony impingements in 7 specimens: 2 at the lateral acromion, 1 at the inferior acromion, 4 scapular notching, and 1 with the glenoid resulting to wear at the 3:00 to 6:00 clock-face position. Impingements occurred in all kinds of tested motions, except for the internal/external rotation at 90° of abduction. The 3 specimens tested in abduction/adduction presented bone loss on the acromion side only. Scapular notching was noted in flexion/extension and in internal/external rotation at 0° of abduction. The humeral polyethylene liner was worn in 2 specimens—1 at the 6:00 to 8:00 clock-face position during internal/external rotation at 0° of abduction and 1 at the 4:00 clock-face position during flexion/extension. The present study revealed that 2 types of impingement interactions coexist and correspond to a frank abutment or lead to a scapular notching (friction-type impingement). Scapular notching seems to be caused by more movements or combination of movements than previously considered, and in particular by movements of flexion/extension and internal/external rotation with the arm at the side. Polyethylene cups with a notch between 3 and 9 o’clock and lower neck-shaft angle (145° or 135°) may play an important role in postoperative ROM limiting scapular notching. PMID:26402829

Outcomes for Arthroscopic Treatment of Anterior Inferior Iliac Spine (Subspine) Hip Impingement

PubMed Central

Nwachukwu, Benedict U.; Chang, Brenda; Fields, Kara; Rinzler, Jeremy; Nawabi, Danyal H.; Ranawat, Anil S.; Kelly, Bryan T.

2017-01-01

Background: Femoroacetabular hip impingement (FAI) is now well recognized; however, anterior inferior iliac spine (AIIS; or subspine) impingement is a form of hip impingement that is underrecognized and can be an important source of hip disability and functional limitation. Purpose: To investigate the outcomes after arthroscopic treatment of AIIS/subspine-related hip impingement in the absence of FAI surgery. Study Design: Case series; Level of evidence, 4. Methods: A prospective institutional hip preservation registry was reviewed to identify patients who underwent arthroscopic AIIS decompression without concurrent treatment of FAI. Primary outcome tools captured in the registry included the modified Harris Hip Score (mHHS), the Hip Outcome Score (HOS), and the International Hip Outcome Tool–33 (iHOT-33). Patients with minimum 1-year follow-up were included. Meaningful outcome improvement was determined per minimal clinically important difference (MCID). Statistical analyses were primarily descriptive. Results: Thirty-three patients with a mean follow-up of 19.1 months (range, 12-44 months) were identified. All patients were female, with a mean ± SD age of 26.1 ± 10.3 years. All patients were found to have an associated labral tear, and the mean acetabular version was increased at 2 and 3 o’clock (14.5° and 19.8°, respectively). Mean preoperative outcome scores on the mHHS, HOS ADL (activities of daily living), HOS sport, and iHOT-33 were 57.2 ± 15.3, 66.9 ± 18.8, 43.9 ± 23.6, and 33.5 ± 18.3, respectively. At final available follow-up, mean scores on these outcome measures were 79.5 ± 19.0, 86.8 ± 15.8, 70.4 ± 32.8, and 65.0 ± 31.0, respectively. By the 1-year follow-up, MCID had been achieved in the majority of patients across all 4 tools. Conclusion: There is a paucity of outcomes evidence on AIIS/subspine-related hip impingement. This study demonstrates that isolated subspine impingement can be a cause of hip disability, even in the absence of FAI. Patients with isolated subspine impingement are more likely to be women and to present with low patient-reported outcome scores. However, meaningful outcome improvement can be achieved with arthroscopic AIIS decompression. PMID:28840150

Outcomes for Arthroscopic Treatment of Anterior Inferior Iliac Spine (Subspine) Hip Impingement.

PubMed

Nwachukwu, Benedict U; Chang, Brenda; Fields, Kara; Rinzler, Jeremy; Nawabi, Danyal H; Ranawat, Anil S; Kelly, Bryan T

2017-08-01

Femoroacetabular hip impingement (FAI) is now well recognized; however, anterior inferior iliac spine (AIIS; or subspine) impingement is a form of hip impingement that is underrecognized and can be an important source of hip disability and functional limitation. To investigate the outcomes after arthroscopic treatment of AIIS/subspine-related hip impingement in the absence of FAI surgery. Case series; Level of evidence, 4. A prospective institutional hip preservation registry was reviewed to identify patients who underwent arthroscopic AIIS decompression without concurrent treatment of FAI. Primary outcome tools captured in the registry included the modified Harris Hip Score (mHHS), the Hip Outcome Score (HOS), and the International Hip Outcome Tool-33 (iHOT-33). Patients with minimum 1-year follow-up were included. Meaningful outcome improvement was determined per minimal clinically important difference (MCID). Statistical analyses were primarily descriptive. Thirty-three patients with a mean follow-up of 19.1 months (range, 12-44 months) were identified. All patients were female, with a mean ± SD age of 26.1 ± 10.3 years. All patients were found to have an associated labral tear, and the mean acetabular version was increased at 2 and 3 o'clock (14.5° and 19.8°, respectively). Mean preoperative outcome scores on the mHHS, HOS ADL (activities of daily living), HOS sport, and iHOT-33 were 57.2 ± 15.3, 66.9 ± 18.8, 43.9 ± 23.6, and 33.5 ± 18.3, respectively. At final available follow-up, mean scores on these outcome measures were 79.5 ± 19.0, 86.8 ± 15.8, 70.4 ± 32.8, and 65.0 ± 31.0, respectively. By the 1-year follow-up, MCID had been achieved in the majority of patients across all 4 tools. There is a paucity of outcomes evidence on AIIS/subspine-related hip impingement. This study demonstrates that isolated subspine impingement can be a cause of hip disability, even in the absence of FAI. Patients with isolated subspine impingement are more likely to be women and to present with low patient-reported outcome scores. However, meaningful outcome improvement can be achieved with arthroscopic AIIS decompression.

40 CFR Appendix A-5 to Part 60 - Test Methods 11 through 15A

Code of Federal Regulations, 2014 CFR

2014-07-01

... are needed. For the first, third, and fourth impingers, use the Greenburg-Smith design, modified by... of the flask. For the second impinger, use the Greenburg-Smith design with the standard tip. 6.1.3...

40 CFR Appendix A-5 to Part 60 - Test Methods 11 through 15A

Code of Federal Regulations, 2011 CFR

2011-07-01

... noncontaminating fittings are needed. For the first, third, and fourth impingers, use the Greenburg-Smith design....) from the bottom of the flask. For the second impinger, use the Greenburg-Smith design with the standard...

40 CFR Appendix A-5 to Part 60 - Test Methods 11 through 15A

Code of Federal Regulations, 2010 CFR

2010-07-01

... noncontaminating fittings are needed. For the first, third, and fourth impingers, use the Greenburg-Smith design....) from the bottom of the flask. For the second impinger, use the Greenburg-Smith design with the standard...

40 CFR Appendix A-5 to Part 60 - Test Methods 11 through 15A

Code of Federal Regulations, 2012 CFR

2012-07-01

... noncontaminating fittings are needed. For the first, third, and fourth impingers, use the Greenburg-Smith design....) from the bottom of the flask. For the second impinger, use the Greenburg-Smith design with the standard...

40 CFR Appendix A-5 to Part 60 - Test Methods 11 through 15A

Code of Federal Regulations, 2013 CFR

2013-07-01

... noncontaminating fittings are needed. For the first, third, and fourth impingers, use the Greenburg-Smith design....) from the bottom of the flask. For the second impinger, use the Greenburg-Smith design with the standard...

Arthroscopic Decompression of a Type III Subspine Impingement.

PubMed

Ilizaliturri, Víctor M; Arriaga Sánchez, Rubén; Suarez-Ahedo, Carlos

2016-12-01

Extra-articular hip impingement refers to a variety of hip disorders causing pain and limited function in young, non-arthritic patients. Recently, there has been an increased focus on analyzing the degree of anterior inferior iliac spine (AIIS) dysmorphism and its correlation with subspine impingement (SSI), defined as abutment between a prominent distal aspect of the AIIS and the anterior aspect of the femoral head-neck junction. Arthroscopic decompression of the AIIS is recognized as an effective treatment for SSI. However, there may be some inherent risks of performing this procedure arthroscopically that require further investigation.

Ultrasonic measurements of the reflection coefficient at a water/polyurethane foam interface.

PubMed

Sagers, Jason D; Haberman, Michael R; Wilson, Preston S

2013-09-01

Measured ultrasonic reflection coefficients as a function of normal incidence angle are reported for several samples of polyurethane foam submerged in a water bath. Three reflection coefficient models are employed as needed in this analysis to approximate the measured data: (1) an infinite plane wave impinging on an elastic halfspace, (2) an infinite plane wave impinging on a single fluid layer overlying a fluid halfspace, and (3) a finite acoustic beam impinging on an elastic halfspace. The compressional wave speed in each sample is calculated by minimizing the sum of squared error (SSE) between the measured and modeled data.

Acute ischiofemoral impingement?

PubMed

García, X G; Turmo, A; Cos, M A; Puigdellívol, J; Til, Ll

2018-03-31

We report a case of rare clinical entity, which comes within the spectrum of hip impingements. The case deals with a 36 year old female, Olympic athlete, who developed ischiofemoral impingement 14 months after a surgical hamstring reattachment. She was treated conservatively and fully recovered. When looking into literature on this matter, we found that it is probably an under-diagnosed problem, particularly in patients with no history of prior surgery. To our knowledge, this is the first case reported after a hamstrings tendon reattachment. Copyright © 2018 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

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.

Space Shuttle Plume and Plume Impingement Study

NASA Technical Reports Server (NTRS)

Tevepaugh, J. A.; Penny, M. M.

1977-01-01

The extent of the influence of the propulsion system exhaust plumes on the vehicle performance and control characteristics is a complex function of vehicle geometry, propulsion system geometry, engine operating conditions and vehicle flight trajectory were investigated. Analytical support of the plume technology test program was directed at the two latter problem areas: (1) definition of the full-scale exhaust plume characteristics, (2) application of appropriate similarity parameters; and (3) analysis of wind tunnel test data. Verification of the two-phase plume and plume impingement models was directed toward the definition of the full-scale exhaust plume characteristics and the separation motor impingement problem.

Anterior Inferior Iliac Spine (AIIS) and Subspine Hip Impingement

PubMed Central

Carton, Patrick; Filan, David

2016-01-01

Summary Background Abnormal morphology of the anterior inferior iliac spine (AIIS) and the subspine region of the acetabular rim are increasingly being recognised as a source of symptomatic extra-articular hip impingement. This review article aims to highlight important differences in the pathogenesis, clinical presentation and management of extra-articular hip impingement from both the AIIS and subspine bony regions, and the outcome following surgical intervention. Methods A literature review was undertaken to examine the supporting evidence for AIIS and subspine hip impingement. A narrative account of the Author’s professional experience in this area, including operative technique for arthroscopic correction, is also presented. Results Abnormal morphology of the AIIS and subspine region has been classified using cadaveric, radiological and arthroscopic means; the clinical presentation and operative treatment has been documented in several case series studies. Dual pathology is often present - recognition and treatment of both intra- and extra-articular components are necessary for good postoperative outcome. Conclusions AIIS and sub-spine hip impingement should be considered as distinct pathological entities, which may also co-exist. Symptom relief can be expected following arthroscopic deformity correction with the treatment of concomitant intra-articular pathology. Failure to recognise and treat the extra-articular component may affect postoperative outcome. Level of evidence V. PMID:28066737

High-Flow-Rate Impinger for the Study of Concentration, Viability, Metabolic Activity, and Ice-Nucleation Activity of Airborne Bacteria.

PubMed

Šantl-Temkiv, Tina; Amato, Pierre; Gosewinkel, Ulrich; Thyrhaug, Runar; Charton, Anaïs; Chicot, Benjamin; Finster, Kai; Bratbak, Gunnar; Löndahl, Jakob

2017-10-03

The study of airborne bacteria relies on a sampling strategy that preserves their integrity and in situ physiological state, e.g. viability, cultivability, metabolic activity, and ice-nucleation activity. Because ambient air harbors low concentrations of bacteria, an effective bioaerosol sampler should have a high sampling efficiency and a high airflow. We characterize a high-flow-rate impinger with respect to particle collection and retention efficiencies in the range 0.5-3.0 μm, and we investigated its ability to preserve the physiological state of selected bacterial species and seawater bacterial community in comparison with four commercial bioaerosol samplers. The collection efficiency increased with particle size and the cutoff diameter was between 0.5 and 1 μm. During sampling periods of 120-300 min, the impinger retained the cultivability, metabolic activity, viability, and ice-nucleation activity of investigated bacteria. Field studies in semiurban, high-altitude, and polar environments included periods of low bacterial air concentrations, thus demonstrating the benefits of the impinger's high flow rate. In conclusion, the impinger described here has many advantages compared with other bioaerosol samplers currently on the market: a potential for long sampling time, a high flow rate, a high sampling and retention efficiency, low costs, and applicability for diverse downstream microbiological and molecular analyses.

Vortex dynamics and wall shear stress behaviour associated with an elliptic jet impinging upon a flat plate

NASA Astrophysics Data System (ADS)

Long, J.; New, T. H.

2016-07-01

Vortical structures and dynamics of a Re h = 2100 elliptic jet impinging upon a flat plate were studied at H/ d h = 1, 2 and 4 jet-to-plate separation distances. Flow investigations were conducted along both its major and minor planes using laser-induced fluorescence and digital particle image velocimetry techniques. Results show that the impingement process along the major plane largely consists of primary jet ring-vortex and wall-separated secondary vortex formations, where they subsequently separate from the flat plate at smaller H/ d h = 1 and 2 separation distances. Key vortex formation locations occur closer to the impingement point as the separation distance increases. Interestingly, braid vortices and rib structures begin to take part in the impingement process at H/ d h = 4 and wave instabilities dominate the flow field. In contrast, significantly more coherent primary and secondary vortices with physically larger vortex core sizes and higher vortex strengths are observed along the minor plane, with no signs of braid vortices and rib structures. Lastly, influences of these different flow dynamics on the major and minor plane instantaneous and mean skin friction coefficient levels are investigated to shed light on the effects of separation distance on the wall shear stress distributions.

Pathways and Hydrography in the Mesoamerican Barrier Reef System Part 1: Circulation

NASA Astrophysics Data System (ADS)

Carrillo, L.; Johns, E. M.; Smith, R. H.; Lamkin, J. T.; Largier, J. L.

2015-10-01

Acoustic Doppler Current Profiler (ADCP) measurements and surface drifters released from two oceanographic cruises conducted during March 2006 and January/February 2007 are used to investigate the circulation off the Mesoamerican Barrier Reef System (MBRS). We show that the MBRS circulation can be divided into two distinct regimes, a northern region dominated by the strong, northward-flowing Yucatan Current, and a southern region with weaker southward coastal currents and the presence of the Honduras Gyre. The latitude of impingement of the Cayman Current onto the coastline varies with time, and creates a third region, which acts as a boundary between the northern and southern circulation regimes. This circulation pattern yields two zones in terms of dispersal, with planktonic propagules in the northern region being rapidly exported to the north, whereas plankton in the southern and impingement regions may be retained locally or regionally. The latitude of the impingement region shifts interannually and intra-annually up to 3° in latitude. Sub-mesoscale features are observed in association with topography, e.g., flow bifurcation around Cozumel Island, flow wake north of Chinchorro Bank and separation of flow from the coast just north of Bahia de la Ascencion. This third feature is evident as cyclonic recirculation in coastal waters, which we call the Ascencion-Cozumel Coastal Eddy. An understanding of the implications of these different circulation regimes on water mass distributions, population connectivity, and the fate of land-based pollutants in the MBRS is critically important to better inform science-based resource management and conservation plans for the MBRS coral reefs.

Motion Imagery and Robotics Application (MIRA): Standards-Based Robotics

NASA Technical Reports Server (NTRS)

Martinez, Lindolfo; Rich, Thomas; Lucord, Steven; Diegelman, Thomas; Mireles, James; Gonzalez, Pete

2012-01-01

This technology development originated from the need to assess the debris threat resulting from soil material erosion induced by landing spacecraft rocket plume impingement on extraterrestrial planetary surfaces. The impact of soil debris was observed to be highly detrimental during NASA s Apollo lunar missions and will pose a threat for any future landings on the Moon, Mars, and other exploration targets. The innovation developed under this program provides a simulation tool that combines modeling of the diverse disciplines of rocket plume impingement gas dynamics, granular soil material liberation, and soil debris particle kinetics into one unified simulation system. The Unified Flow Solver (UFS) developed by CFDRC enabled the efficient, seamless simulation of mixed continuum and rarefied rocket plume flow utilizing a novel direct numerical simulation technique of the Boltzmann gas dynamics equation. The characteristics of the soil granular material response and modeling of the erosion and liberation processes were enabled through novel first principle-based granular mechanics models developed by the University of Florida specifically for the highly irregularly shaped and cohesive lunar regolith material. These tools were integrated into a unique simulation system that accounts for all relevant physics aspects: (1) Modeling of spacecraft rocket plume impingement flow under lunar vacuum environment resulting in a mixed continuum and rarefied flow; (2) Modeling of lunar soil characteristics to capture soil-specific effects of particle size and shape composition, soil layer cohesion and granular flow physics; and (3) Accurate tracking of soil-borne debris particles beginning with aerodynamically driven motion inside the plume to purely ballistic motion in lunar far field conditions.

Characterization of solid particle erosion resistance of ductile metals based on their properties

NASA Technical Reports Server (NTRS)

Rao, P. V.; Buckley, D. H.

1985-01-01

This paper presents experimental results pertaining to spherical glass bead and angular crushed glass particle impingement. A concept of energy absorption to explain the failure of material is proposed and is correlated with the erosion characteristics of several pure metals. Analyses of extensive erosion data indicate that the properties - surface energy, specific melting energy, strain energy, melting point, bulk modulus, hardness, atomic volume - and the product of the parameters - linear coefficient of thermal expansion x bulk modulus x temperature rise required for melting, and ultimate resilience x hardness - exhibit the best correlations. The properties of surface energy and atomic volume are suggested for the first time for correlation purposes and are found to correlate well with erosion rates at different angles of impingement. It further appears that both energy and thermal properties contribute to the total erosion.

Effects of oblique air flow on burning rates of square ethanol pool fires.

PubMed

Tao, Changfa; He, Yaping; Li, Yuan; Wang, Xishi

2013-09-15

The effects of downward airflow on the burning rate and/or burning intensity of square alcohol pool fires for different airflow speeds and directions have been studied experimentally in an inclined wind tunnel. An interesting flame-wrapping phenomenon, caused by impingement of air flow, was observed. The mass burning intensity was found to increase with the airflow speed and the impinging angle. The fuel pan rim temperatures were also measured to study the effect of wind direction and speed on heat transfer from the flame to the fuel source. A model based on heat transfer analysis was developed to correlate the burning intensity with the pan rim characteristic temperature. A good correlation was established between the model results and the experimental results. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of H2O2 injection patterns on catalyst bed characteristics

NASA Astrophysics Data System (ADS)

Kang, Hongjae; Lee, Dahae; Kang, Shinjae; Kwon, Sejin

2017-01-01

The decomposition process of hydrogen peroxide can be applied to a bipropellant thruster, as well as to monopropellant thruster. To provide a framework for the optimal design of the injector and catalyst bed depending on a type of thruster, this research scrutinizes the effect of injection patterns of the propellant on the performance of the catalyst bed. A showerhead injector and impinging jet injector were tested with a 50 N monopropellant thruster. Manganese oxide/γ-alumina catalyst and manganese oxide/lanthanum-doped alumina catalyst were prepared and tested. The showerhead injector provided a fast response time, suitable for pulse mode operation. The impinging jet injector mitigated the performance instability and catalyst attrition that is favorable for large scale bipropellant thrusters. The design of a dual catalyst bed was conceptually proposed based on the data obtained from firing tests.

An empirically derived basis for calculating the area, rate, and distribution of water-drop impingement on airfoils

NASA Technical Reports Server (NTRS)

Bergrun, Norman R

1952-01-01

An empirically derived basis for predicting the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The concepts involved represent an initial step toward the development of a calculation technique which is generally applicable to the design of thermal ice-prevention equipment for airplane wing and tail surfaces. It is shown that sufficiently accurate estimates, for the purpose of heated-wing design, can be obtained by a few numerical computations once the velocity distribution over the airfoil has been determined. The calculation technique presented is based on results of extensive water-drop trajectory computations for five airfoil cases which consisted of 15-percent-thick airfoils encompassing a moderate lift-coefficient range. The differential equations pertaining to the paths of the drops were solved by a differential analyzer.

[Efficacies of arthroscopic debridement and olecranon fossa plasty in the treatment of osteoarthritis and posterior elbow impingement].

PubMed

Liu, Yu-jie; Wang, Jun-liang; Li, Hai-feng; Qi, Wei; Wang, Ning

2012-07-17

To evaluate the efficacies of arthroscopic debridement and removal of osteophyma for olecroanon and olecranon fossa plasty for posterior impingement of elbow joint. Between 1999 and 2008, a total of 21 cases were diagnosed with osteoarthritis and posterior elbow impingement. There were 15 males and 6 females. And there were 16 right and 15 left cases. They included volleyball players (n = 7), tennis players (n = 7), golf enthusiasts (n = 4) and fencers (n = 3). The average duration of onset-operation was 3.5 years (range: 2.5 - 8). Arthroscopic exploration revealed synovial hyperplasia hypertrophy, cartilage degeneration and olecranon fossa hyperplasia with deformed olecranon fossa. Debridement and plasty were performed. Loose bodies were removed from elbow joint in 6 patients. Partial resection of posterior olecranon tip was performed and osteophytes or fibrous tissue removed in this area. Dynamic observation showed no posterior elbow impingement. Postoperative follow-up was conducted in 19 cases and 2 cases became lost to follow-up. The average follow-up period was 25.3 months (range: 18 - 42). All patients were evaluated preoperatively and postoperatively with the Hospital for Special Surgery Elbow Assessment Scale. The outcomes were excellent (n = 12), good (n = 7) and fair (n = 2). Postoperative patients elbow swelling and pain relieve, sports and life function returns to normal, elbow flexion and rotating mobility obviously improved. With the elbow radiological films to measure the range of motion, the average range of motion was 90.5° preoperatively and improved to 130° postoperatively. There was significant improvement in all cases. Posterior elbow impingement is caused by hyperextension trauma and elbow overuse during specific sporting activities. Arthroscopic debridement and olecroanon or olecranon fossa plasty demonstrates excellent results for posterior impingement of elbow joint.

Quantitative and qualitative analyses of subacromial impingement by kinematic open MRI.

PubMed

Tasaki, Atsushi; Nimura, Akimoto; Nozaki, Taiki; Yamakawa, Akira; Niitsu, Mamoru; Morita, Wataru; Hoshikawa, Yoshimitsu; Akita, Keiichi

2015-05-01

Quantitative and qualitative kinematic analyses of subacromial impingement by 1.2T open MRI were performed to determine the location of impingement and the involvement of the acromioclavicular joint. In 20 healthy shoulders, 10 sequential images in the scapular plane were taken in a 10-s pause at equal intervals from 30° to maximum abduction in neutral and internal rotation. The distances between the rotator cuff (RC) and the acromion and the acromioclavicular joint were measured. To comprehend the positional relationships, cadaveric specimens were also observed. Although asymptomatic, the RC came into contact with the acromion and the acromioclavicular joint in six and five cases, respectively. The superior RC acted as a depressor for the humeral head against the acromion as the shoulder elevated. The mean elevation angle and distance at the closest position between the RC and the acromion in neutral rotation were 93.5° and 1.6 mm, respectively, while those between the RC and the acromioclavicular joint were 86.7° and 2.0 mm. When comparing this distance and angle, there was no significant difference between the RC to the acromion and to the acromioclavicular joint. The minimum distance between the RC and the acromion was significantly shorter than that between the greater tuberosity and the acromion. The location of RC closest to the acromion and the acromioclavicular joint differed significantly. Although asymptomatic, contact was found between the RC and the acromion and the acromioclavicular joint. The important role of the RC to prevent impingement was observed, and hence, dysfunction of the RC could lead to impingement that could result in a RC lesion. The RC lesions may differ when they are caused by impingement from either the acromion or the acromioclavicular joint.

Optimal acetabular component orientation estimated using edge-loading and impingement risk in patients with metal-on-metal hip resurfacing arthroplasty.

PubMed

Mellon, Stephen J; Grammatopoulos, George; Andersen, Michael S; Pandit, Hemant G; Gill, Harinderjit S; Murray, David W

2015-01-21

Edge-loading in patients with metal-on-metal resurfaced hips can cause high serum metal ion levels, the development of soft-tissue reactions local to the joint called pseudotumours and ultimately, failure of the implant. Primary edge-loading is where contact between the femoral and acetabular components occurs at the edge/rim of the acetabular component whereas impingement of the femoral neck on the acetabular component's edge causes secondary or contrecoup edge-loading. Although the relationship between the orientation of the acetabular component and primary edge-loading has been identified, the contribution of acetabular component orientation to impingement and secondary edge-loading is less clear. Our aim was to estimate the optimal acetabular component orientation for 16 metal-on-metal hip resurfacing arthroplasty (MoMHRA) subjects with known serum metal ion levels. Data from motion analysis, subject-specific musculoskeletal modelling and Computed Tomography (CT) measurements were used to calculate the dynamic contact patch to rim (CPR) distance and impingement risk for 3416 different acetabular component orientations during gait, sit-to-stand, stair descent and static standing. For each subject, safe zones free from impingement and edge-loading (CPR <10%) were defined and, consequently, an optimal acetabular component orientation was determined (mean inclination 39.7° (SD 6.6°) mean anteversion 14.9° (SD 9.0°)). The results of this study suggest that the optimal acetabular component orientation can be determined from a patient's motion and anatomy. However, 'safe' zones of acetabular component orientation associated with reduced risk of dislocation and pseudotumour are also associated with a reduced risk of edge-loading and impingement. Copyright © 2014 Elsevier Ltd. All rights reserved.

Surgical hip dislocation for treatment of cam femoroacetabular impingement.

PubMed

Chaudhary, Milind M; Chaudhary, Ishani M; Vikas, K N; KoKo, Aung; Zaw, Than; Siddhartha, A

2015-01-01

Cam femoroacetabular impingement is caused by a misshapen femoral head with a reduced head neck offset, commonly in the anterolateral quadrant. Friction in flexion, adduction and internal rotation causes limitation of the hip movements and pain progressively leading to labral and chondral damage and osteoarthritis. Surgical hip dislocation described by Ganz permits full exposure of the hip without damaging its blood supply. An osteochondroplasty removes the bump at the femoral head neck junction to recreate the offset for impingement free movement. Sixteen patients underwent surgery with surgical hip dislocation for the treatment of cam femoroacetabular impingement by open osteochondroplasty over last 6 years. Eight patients suffered from sequelae of avascular necrosis (AVN). Three had a painful dysplastic hip. Two had sequelae of Perthes disease. Three had combined cam and pincer impingement caused by retroversion of acetabulum. All patients were operated by the trochanteric flip osteotomy with attachments of gluteus medius and vastus lateralis, dissection was between the piriformis and gluteus minimus preserving the external rotators. Z-shaped capsular incision and dislocation of the hip was done in external rotation. Three cases also had subtrochanteric osteotomy. Two cases of AVN also had an intraarticular femoral head reshaping osteotomy. Goals of treatment were achieved in all patients. No AVN was detected after a 6 month followup. There were no trochanteric nonunions. Hip range of motion improved in all and Harris hip score improved significantly in 15 of 16 cases. Mean alpha angle reduced from 86.13° (range 66°-108°) to 46.35° (range 39°-58°). Cam femoroacetabular Impingement causing pain and limitation of hip movements was treated by open osteochondroplasty after surgical hip dislocation. This reduced pain, improved hip motion and gave good to excellent results in the short term.

Fast Ignition and Sustained Combustion of Ionic Liquids

NASA Technical Reports Server (NTRS)

Joshi, Prakash B. (Inventor); Piper, Lawrence G. (Inventor); Oakes, David B. (Inventor); Sabourin, Justin L. (Inventor); Hicks, Adam J. (Inventor); Green, B. David (Inventor); Tsinberg, Anait (Inventor); Dokhan, Allan (Inventor)

2016-01-01

A catalyst free method of igniting an ionic liquid is provided. The method can include mixing a liquid hypergol with a HAN (Hydroxylammonium nitrate)-based ionic liquid to ignite the HAN-based ionic liquid in the absence of a catalyst. The HAN-based ionic liquid and the liquid hypergol can be injected into a combustion chamber. The HAN-based ionic liquid and the liquid hypergol can impinge upon a stagnation plate positioned at top portion of the combustion chamber.

Single-drop impingement onto a wavy liquid film and description of the asymmetrical cavity dynamics

NASA Astrophysics Data System (ADS)

van Hinsberg, Nils Paul; Charbonneau-Grandmaison, Marie

2015-07-01

The present paper is devoted to an experimental investigation of the cavity formed upon a single-drop impingement onto a traveling solitary surface wave on a deep pool of the same liquid. The dynamics of the cavity throughout its complete expansion and receding phase are analyzed using high-speed shadowgraphy and compared to the outcomes of drop impingements onto steady liquid surface films having equal thickness. The effects of the surface wave velocity, amplitude and phase, drop impingement velocity, and liquid viscosity on the cavity's diameter and depth evolution are accurately characterized at various time instants. The wave velocity induces a distinct and in time increasing inclination of the cavity in the wave propagation direction. In particular for strong waves an asymmetrical distribution of the radial expansion and retraction velocity along the cavity's circumference is observed. A linear dependency between the absolute Weber number and the typical length and time scales associated with the cavity's maximum depth and maximum diameter is reported.

An Experimental Investigation of the Flow Structure of Supersonic Impinging Jets

NASA Technical Reports Server (NTRS)

Henderson, Brenda; Bridges, James; Wernet, Mark

2002-01-01

An experimental investigation into the jet structure associated with sound production by a supersonic impinging jet is presented. Large plate impinging tones are investigated for a nozzle pressure ratio (NPR) of 4 and nozzle-to-plate spacings between 1 and 5 nozzle exit diameters, where NPR is equal to the ratio of the stagnation pressure to the pressure at the nozzle lip. Results from phase-locked shadowgraph and phase-averaged digital particle image velocimetry (DPIV) studies indicate that, during the oscillation cycle, the Mach disk oscillates axially, a well defined recirculation zone is created in the subsonic impingement region and moves toward the plate, and the compression and expansion regions in the outer supersonic flow move downstream, Sound appears to be generated in the wall jet at approximately 2.6R from the jet axis, where R is the nozzle exit radius. The oscillatory motion in the wall jet is the result of the periodic fluid motion in the near wall region.

Mach number effect on jet impingement heat transfer.

PubMed

Brevet, P; Dorignac, E; Vullierme, J J

2001-05-01

An experimental investigation of heat transfer from a single round free jet, impinging normally on a flat plate is described. Flow at the exit plane of the jet is fully developed and the total temperature of the jet is equal to the ambient temperature. Infrared measurements lead to the characterization of the local and averaged heat transfer coefficients and Nusselt numbers over the impingement plate. The adiabatic wall temperature is introduced as the reference temperature for heat transfer coefficient calculation. Various nozzle diameters from 3 mm to 15 mm are used to make the injection Mach number M vary whereas the Reynolds number Re is kept constant. Thus the Mach number influence on jet impingement heat transfer can be directly evaluated. Experiments have been carried out for 4 nozzle diameters, for 3 different nozzle-to-target distances, with Reynolds number ranging from 7200 to 71,500 and Mach number from 0.02 to 0.69. A correlation is obtained from the data for the average Nusselt number.

Mixed convection cooling of a cylinder using slot jet impingement at different circumferential angles

NASA Astrophysics Data System (ADS)

Naderipour, S.; Yousefi, T.; Ashjaee, M.; Naylor, D.

2016-08-01

An experimental study using Mach-Zehnder interferometer has been carried out to investigate the heat transfer from an isothermal horizontal circular cylinder, which is exposed to an air slot jet at different angles of jet impingement. A square edged nozzle is mounted parallel with the cylinder axis and jet flow impinges on the side of the cylinder at angles Θ = 0°, 30°, 60° and 90°. The Reynolds number varied from 240 to 1900 while the Grashof number and slot- to cylinder-spacing is kept constant at Gr = 22,300 and H/w = 7 respectively. The Richardson number varied from 0.006 to 0.4. The flow field is greatly influenced by the slot exit velocity and the buoyancy force due to density change. The local Nusselt number around the cylinder has been calculated using the infinite fringe interferograms at 10° intervals. Average Nusselt number shows that heat transfer is decreased when the angle of jet impingement is increased .

ANSYS Fluent Modelling of an Underexpanded Supersonic Sootblower Jet Impinging into Recovery Boiler Tube Geometries

NASA Astrophysics Data System (ADS)

Doroudi, Shahed

Sootblowers generate high pressure supersonic steam jets to control fireside deposition on heat transfer tubes of a kraft recovery boiler. Sootblowing is energy expensive, using 3-12% of the mill's total steam production. This motivates research on the dynamics of sootblower jet interaction with tubes and deposits, to optimize their use. A CFD investigation was performed using ANSYS Fluent 15.0 to model three-dimensional steady-state impingement of a Mach 2.5 mildly underexpanded (PR 1.2) air jet onto arrays of cylindrical tubes with and without fins, at various nozzle-to-tube centerline offsets. A free jet and four impingement cases for each of the economizer and generating bank geometries are compared to experimental visualizations. Pressure distributions on impinging surfaces suggest that the fins in the economizer produce a reduced but uniform sootblowing force. Pressure contours along the tubes (in the vertical direction) show a sharp decline one tube diameter away from the jet mid-plane.

ARTHROSCOPIC TREATMENT OF FEMOROACETABULAR IMPINGEMENT

PubMed Central

Polesello, Giancarlo C.; Queiroz, Marcelo C.; Ono, Nelson K.; Honda, Emerson K.; Guimarāes, Rodrigo P; Junior, Walter Ricioli

2015-01-01

Objective: The purpose of this study is to evaluate the short-term follow-up results of arthroscopic treatment of femoroacetabular impingement. Our hypothesis is that arthroscopic treatment results are favorable. Methods: Between August 2003 and August 2007, 28 hips had femoroacetabular impingement treated by hip arthroscopy. The mean age was 34 years, with mean follow-up period of 27 months. Clinical results were graded with the modified Harris hip score, which was measured pre- and postoperatively. Patients had also their internal rotation analyzed. These parameters were calculated by using Wilcoxon's t test for analysis of nonparametric paired samples performed. Results: The mean preoperative Harris Hip Score was 54.2, improving to 94.8 postoperatively (p<0,001). The mean increase was 37.5 points. We had 4 good results (15%) and 24 excellent results (85%). Preoperatively, the patients had a mean internal rotation of 17°, and, postoperatively, 36°. The average internal rotation increase was 19° (p<0,001). Conclusions: The arthroscopic treatment of femoroacetabular impingement presents satisfactory results. PMID:27004177

Apollo Video Photogrammetry Estimation Of Plume Impingement Effects

NASA Technical Reports Server (NTRS)

Immer, Christopher; Lane, John; Metzger, Philip T.; Clements, Sandra

2008-01-01

The Constellation Project's planned return to the moon requires numerous landings at the same site. Since the top few centimeters are loosely packed regolith, plume impingement from the Lander ejects the granular material at high velocities. Much work is needed to understand the physics of plume impingement during landing in order to protect hardware surrounding the landing sites. While mostly qualitative in nature, the Apollo Lunar Module landing videos can provide a wealth of quantitative information using modem photogrammetry techniques. The authors have used the digitized videos to quantify plume impingement effects of the landing exhaust on the lunar surface. The dust ejection angle from the plume is estimated at 1-3 degrees. The lofted particle density is estimated at 10(exp 8)- 10(exp 13) particles per cubic meter. Additionally, evidence for ejection of large 10-15 cm sized objects and a dependence of ejection angle on thrust are presented. Further work is ongoing to continue quantitative analysis of the landing videos.

Mixing at double-Tee junctions with unequal pipe sizes in ...

EPA Pesticide Factsheets

Pipe flow mixing with various solute concentrations and flow rates at pipe junctions is investigated. The degree of mixing affects the spread of contaminants in a water distribution system. Many studies have been conducted on the mixing at the cross junctions. Yet a few have focused on double-Tee junctions of unequal pipe sizes. To investigate the solute mixing at double-Tee junctions with unequal pipe sizes, a series of experiments were conducted in a turbulent regime (Re=12500–50000) with different Reynolds number ratios and connecting pipe lengths. It is shown that dimensionless outlet concentrations depended on mixing mechanism at the impinging interface of junctions. Junction with a larger pipe size ratio is associated with more complete mixing. The inlet Reynolds number ratio affects mixing more strongly than the outlet Reynolds number ratio. Furthermore, the dimensionless connecting pipe length in a double-Tee played an important and complicated role in the flow mixing. Based on these results, two-dimensional isopleth maps were developed for the calculation of normalized north outlet concentration. This journal article is to communicate the research results on pipe juncture mixing, a widespread and important phenomena in distribution system water quality analysis. The research outcome improves EPANET modeling capability for safe water supplies. In addition, the research is one of the outputs from the EPA-MOST bilateral cooperative research Project #1

Realizing broad-bandwidth visible wavelength photodiode based on solution-processed ZnPc/PC71BM dyad

NASA Astrophysics Data System (ADS)

Zafar, Qayyum; Fatima, Noshin; Karimov, Khasan S.; Ahmed, Muhammad M.; Sulaiman, Khaulah

2017-02-01

Herein, we demonstrate a solution-processed visible wavelength organic photodiode (OPD) using donor/acceptor dyad of zinc phthalocyanine (ZnPc) and [6,6]-phenyl-C71-butyric-acid methyl ester (PC71BM), respectively. The synergic absorption profiles of both ZnPc and PC71BM moieties have been exploited to realize broader (350 and 800 nm) and consistent absorption spectrum of the photoactive film. The optimum loading ratio (by volume) of D/A dyad has been estimated to be 1:0.8, via quenching phenomenon in ZnPc photoluminescence spectrum. The performance of the OPD has been evaluated by detecting the photocurrent density with respect to varied illumination levels (0-150 mW/cm2) of impinging light at different reverse bias conditions. Under identical reverse bias mode, the photocurrent density has shown significant upsurge as the incident intensity of light is increased; ultimately leading to the significantly higher responsivity (162.4 μA/W) of the fabricated diode. The light to dark current density ratio (Jph/Jd) of the device at 3 V reverse bias has been calculated to be ∼20.12. The transient photocurrent density response of the fabricated OPD has also been characterized at -4 V operational bias under switch ON/OFF illumination. The measured response and recovery time for the fabricated OPD are ∼200 and 300 ms, respectively.

Effectiveness of Kinesiotaping and Subacromial Corticosteroid Injection in Shoulder Impingement Syndrome.

PubMed

Şahin Onat, Şule; Biçer, Seda; Şahin, Zehra; Küçükali Türkyilmaz, Ayşegül; Kara, Murat; Özbudak Demir, Sibel

2016-08-01

The aim of this study was to investigate whether kinesiotaping or subacromial corticosteroid injection provides additional benefit when used with nonsteroidal anti-inflammatory drugs (NSAIDs) in patients with shoulder impingement syndrome. Patients with shoulder impingement syndrome were divided into 3 groups as follows: NSAID group (n = 33), kinesiotaping group (kinesiotaping + NSAID) (n = 33), and injection group (subacromial corticosteroid injection + NSAID) (n = 33). Outcome measures including visual analog scale, shoulder ranges of motion, Shoulder Disability Questionnaire, and University of California-Los Angeles (UCLA) scale were evaluated before and after the treatment (fourth week). A total of 99 patients (21 male and 78 female patients) were enrolled in this study. Demographic and baseline clinical characteristics of the groups (except for body mass index and visual analog scale at night, both P = 0.05) were similar between the groups (all P > 0.05). Clinical parameters were found to have improved in the 3 groups (all P < 0.001). While the kinesiotaping and injection groups showed similar improvements (all P > 0.05), each group had better outcome than did the NSAID group as regards pain (activity visual analog scale), ranges of motion, and Shoulder Disability Questionnaire and UCLA scale scores (all P < 0.05). Addition of kinesiotaping or subacromial corticosteroid injection to NSAID treatment seems to have better/similar effectiveness in patients with shoulder impingement syndrome. Therefore, kinesiotaping might serve as an alternative treatment in case (injection of) corticosteroids are contraindicated. Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES:: Upon completion of this article, the reader should be able to: (1) Delineate appropriate treatment options for shoulder impingement syndrome; (2) Identify treatment benefits of kinesiotaping and corticosteroid injections in shoulder impingement syndrome; and (3) Incorporate kinesiotaping and corticosteroid injections into the treatment plan for patients with shoulder impingement syndrome. Advanced : The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The Association of Academic Physiatrists designates this activity for amaximumof 1.5 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Exploration of Impinging Water Spray Heat Transfer at System Pressures Near the Triple Point

NASA Technical Reports Server (NTRS)

Golliher, Eric L.; Yao, Shi-Chune

2013-01-01

The heat transfer of a water spray impinging upon a surface in a very low pressure environment is of interest to cooling of space vehicles during launch and re-entry, and to industrial processes where flash evaporation occurs. At very low pressure, the process occurs near the triple point of water, and there exists a transient multiphase transport problem of ice, water and water vapor. At the impingement location, there are three heat transfer mechanisms: evaporation, freezing and sublimation. A preliminary heat transfer model was developed to explore the interaction of these mechanisms at the surface and within the spray.

Aircraft anti-insect system

NASA Technical Reports Server (NTRS)

Spiro, Clifford Lawrence (Inventor); Fric, Thomas Frank (Inventor); Leon, Ross Michael (Inventor)

1997-01-01

Insect debris is removed from or prevented from adhering to insect impingement areas of an aircraft, particularly on an inlet cowl of an engine, by heating the area to 180.degree.-500.degree. C. An apparatus comprising a means to bring hot air from the aircraft engine to a plenum contiguous to the insect impingement area provides for the heating of the insect impingement areas to the required temperatures. The plenum can include at least one tube with a plurality of holes contained in a cavity within the inlet cowl. It can also include an envelope with a plurality of holes on its surface contained in a cavity within the inlet cowl.

Cold plate with combined inclined impingement and ribbed channels

DOEpatents

Parida, Pritish R.

2015-12-22

Heat transfer devices and methods for making the same that include a first enclosure having at least one inlet port; a second enclosure having a bottom plate and one or more dividing walls to establish channels, at least one internal surface of each channel having rib structures to create turbulence in a fluid flow; and a jet plate connecting the first enclosure and the second enclosure having impinging jets that convey fluid from the first enclosure to the channels, said impinging jets being set at an angular deviation from normal to cause local acceleration of fluid and to increase a local heat transfer rate.

COMPARISON OF METHODS FOR DETECTION AND ENUMERATION OF AIRBORNE MICROORGANISMS COLLECTED BY LIQUID IMPINGEMENT

EPA Science Inventory

Bacterial agents and cell components can be spread as bioaerosols, producing infections and asthmatic problems. This study compares four methods for the detection and enumeration of aerosolized bacteria collected in an AGI-30 impinger. Changes in the total and viable concentratio...

Influence of a weak gravitational wave on a bound system of two point-masses. [of binary stars

NASA Technical Reports Server (NTRS)

Turner, M. S.

1979-01-01

The problem of a weak gravitational wave impinging upon a nonrelativistic bound system of two point masses is considered. The geodesic equation for each mass is expanded in terms of two small parameters, v/c and dimensionless wave amplitude, in a manner similar to the post-Newtonian expansion; the geodesic equations are resolved into orbital and center-of-mass equations of motion. The effect of the wave on the orbit is determined by using Lagrange's planetary equations to calculate the time evolution of the orbital elements. The gauge properties of the solutions and, in particular, the gauge invariance of the secular effects are discussed.

Shocklike soliton because of an impinge of protons and electrons solar particles with Venus ionosphere

NASA Astrophysics Data System (ADS)

Moslem, W. M.; Rezk, S.; Abdelsalam, U. M.; El-Labany, S. K.

2018-04-01

This paper introduces an investigation of shocklike soliton or small amplitude Double Layers (DLs) in a collisionless plasma, consisting of positive and negative ions, nonthermal electrons, as well as solar wind streaming protons and electrons. Gardner equation is derived and its shocklike soliton solution is obtained. The model is employed to recognize a possible nonlinear wave at Venus ionosphere. The results indicate that the number densities and velocities of the streaming particles play crucial role to determine the polarity and characteristic features (amplitude and width) of the shocklike soliton waves. An electron streaming speed modifies a negative shocklike wave profile, while an ion streaming speed modulates a positive shocklike wave characteristic.

Experimental study of the spray characteristics of a research airblast atomizer

NASA Technical Reports Server (NTRS)

Acosta, W. A.

1985-01-01

Airblast atomization was studied using a especially designed atomizer in which the liquid first impinges on a splash plate, then is directed radially outward and is atomized by the air passing through two concentric, vaned swirlers that swirl the air in opposite directions. The effect of flow conditions, air mass velocity (mass flow rate per unit area) and liquid to air ratio on the mean drop size was studied. Seven different ethanol solutions were used to simulate changes in fuel physical properties. The range of atomizing air velocities was from 30 to 80 m/s. The mean drop diameter was measured at ambient temperature (295 K) and atmospheric pressure.

Experimental study of the spray characteristics of a research airblast atomizer

NASA Technical Reports Server (NTRS)

Acosta, W. A.

1985-01-01

Airblast atomization was studied using a especially designed atomizer in which the liquid first impinges on a splash plate, then is directed radically outward and is atomized by the air passing through two concentric, vaned swirlers that swirl the air in opposite directions. The effect of flow conditions, air mass velocity (mass flow rate per unit area) and liquid to air ratio on the mean drop size was studied. Seven different ethanol solutions were used to simulate changes in fuel physical properties. The range of atomizing air velocities was from 30 to 80 m/s. The mean drop diameter was measured at ambient temperature (295 K) and atmospheric pressure.

Experimental and Analytical Investigation of the Coolant Flow Characteristics in Cooled Turbine Airfoils

NASA Technical Reports Server (NTRS)

Damerow, W. P.; Murtaugh, J. P.; Burggraf, F.

1972-01-01

The flow characteristics of turbine airfoil cooling system components were experimentally investigated. Flow models representative of leading edge impingement, impingement with crossflow (midchord cooling), pin fins, feeder supply tube, and a composite model of a complete airfoil flow system were tested. Test conditions were set by varying pressure level to cover the Mach number and Reynolds number range of interest in advanced turbine applications. Selected geometrical variations were studied on each component model to determine these effects. Results of these tests were correlated and compared with data available in the literature. Orifice flow was correlated in terms of discharge coefficients. For the leading edge model this was found to be a weak function of hole Mach number and orifice-to-impinged wall spacing. In the impingement with crossflow tests, the discharge coefficient was found to be constant and thus independent of orifice Mach number, Reynolds number, crossflow rate, and impingement geometry. Crossflow channel pressure drop showed reasonable agreement with a simple one-dimensional momentum balance. Feeder tube orifice discharge coefficients correlated as a function of orifice Mach number and the ratio of the orifice-to-approach velocity heads. Pin fin data was correlated in terms of equivalent friction factor, which was found to be a function of Reynolds number and pin spacing but independent of pin height in the range tested.

Spray drying of budesonide, formoterol fumarate and their composites-II. Statistical factorial design and in vitro deposition properties.

PubMed

Tajber, L; Corrigan, O I; Healy, A M

2009-02-09

The aim of this study was to investigate the effect of changing spray drying parameters on the production of a budesonide/formoterol fumarate 100:6 (w/w) composite. The systems were spray dried as solutions from 95% ethanol/5% water (v/v) using a Büchi 191-Mini Spray Dryer. A 2(5-1) factorial design study was undertaken to assess the consequence of altering spray drying processing variables on particle characteristics. The processing parameters that were studied were inlet temperature, spray drier airflow rate, pump rate, aspirator setting and feed concentration. Each batch of the resulting powder was characterised in terms of thermal and micromeritic properties as well as an in vitro deposition by twin impinger analysis. Overall, the parameter that had the greatest influence on each response investigated was production yield - airflow (higher airflow giving greater yields), median particle size - airflow (higher airflow giving smaller particle sizes) and Carr's compressibility index - feed concentration (lower feed concentration giving smaller Carr's indices). A six- to seven-fold difference in respirable fraction can be observed by changing the spray drying process parameters. The co-spray dried composite system which displayed best in vitro deposition characteristics, showed a 2.6-fold increase in respirable fraction in the twin impinger experiments and better dose uniformity compared with the physical mix of micronised powders.

Electrical Aspects of Impinging Flames

NASA Astrophysics Data System (ADS)

Chien, Yu-Chien

This dissertation examines the use of electric fields as one mechanism for controlling combustion as flames are partially extinguished when impinging on nearby surfaces. Electrical aspects of flames, specifically, the production of chemi-ions in hydrocarbon flames and the use of convective flows driven by these ions, have been investigated in a wide range of applications in prior work but despite this fairly comprehensive effort to study electrical aspects of combustion, relatively little research has focused on electrical phenomena near flame extinguishment, nor for flames near impingement surfaces. Electrical impinging flames have complex properties under global influences of ion-driven winds and flow field disturbances from the impingement surface. Challenges of measurements when an electric field is applied in the system have limited an understanding of changes to the flame behavior and species concentrations caused by the field. This research initially characterizes the ability of high voltage power supplies to respond on sufficiently short time scales to permit real time electrical flame actuation. The study then characterizes the influence of an electric field on the impinging flame shape, ion current and flow field of the thermal plume associated with the flame. The more significant further examinations can be separated into two parts: 1) the potential for using electric fields to control the release of carbon monoxide (CO) from surface-impinging flames, and 2) an investigation of controlling electrically the heat transfer to a plate on which the flame impinges. Carbon monoxide (CO) results from the incomplete oxidation of hydrocarbon fuels and, while CO can be desirable in some syngas processes, it is usually a dangerous emission from forest fires, gas heaters, gas stoves, or furnaces where insufficient oxygen in the core reaction does not fully oxidize the fuel to carbon dioxide and water. Determining how carbon monoxide is released and how heat transfer from the flame to the plate can be controlled using the electric field are the two main goals of this research. Multiple diagnostic techniques are employed such as OH chemiluminescence to identify the reaction zone, OH PLIF to characterize the location of this radical species, CO released from the flame, IR imaging and OH PLIF thermometry to understand the surface and gas temperature distribution, respectively. The principal finding is that carbon monoxide release from an impinging diffusion flame results from the escape of carbon monoxide created on the fuel side of the flame along the boundary layer near the surface where it avoids oxidation by OH, which sits to the air side of the reaction sheet interface. In addition, the plate proximity to the flame has a stronger influence on the emission of toxic carbon monoxide than does the electric field strength. There is, however, a narrow region of burner to surface distance where the electric field is most effective. The results also show that heat transfer can be spatially concentrated effectively using an electric field driven ion wind, particularly at some burner to surface distances.

Novel neutron sources at the Radiological Research Accelerator Facility

PubMed Central

Xu, Yanping; Garty, Guy; Marino, Stephen A.; Massey, Thomas N.; Randers-Pehrson, Gerhard; Johnson, Gary W.; Brenner, David J.

2012-01-01

Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10–20 micron in diameter. This facility is based on a Proton Microbeam, impinging on a thin lithium target near the threshold of the 7Li(p,n)7Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components. PMID:22545061

Novel neutron sources at the Radiological Research Accelerator Facility.

PubMed

Xu, Yanping; Garty, Guy; Marino, Stephen A; Massey, Thomas N; Randers-Pehrson, Gerhard; Johnson, Gary W; Brenner, David J

2012-03-16

Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons.We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target.A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a Proton Microbeam, impinging on a thin lithium target near the threshold of the (7)Li(p,n)(7)Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.

Novel neutron sources at the Radiological Research Accelerator Facility

DOE PAGES

Xu, Yanping; Garty, G.; Marino, S. A.; ...

2012-03-16

Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will bemore » based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a proton microbeam, impinging on a thin lithium target near the threshold of the Li-7(p,n)Be-7 reaction. Lastly, this novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.« less

Anterior Impingement Syndrome of the Ankle Caused by Osteoid Osteoma in the Talar Neck Treated with Arthroscopy and 3D C-Arm-Based Imaging.

PubMed

Ikegami, Masachika; Matsumoto, Takumi; Chang, Song Ho; Kobayashi, Hiroshi; Shinoda, Yusuke; Tanaka, Sakae

2017-01-01

Osteoid osteoma in periarticular lesions tends to have an unusual presentation that likely leads to a delayed or missed diagnosis compared with a typical osteoid osteoma in the metaphysis or diaphysis of the long bone. In cases that are unresponsive to conservative treatment, surgical interventions including en bloc resection, computed tomography-guided percutaneous treatment, and arthroscopic resection have been performed; however, these methods frequently result in inadequate tumor resection and recurrence. Here we present a case of a 16-year-old girl with osteoid osteoma in the talar neck presenting as anterior impingement syndrome due to marked synovitis in the ankle joint which was successfully treated without complications by arthroscopic synovectomy and tumor resection followed by intraoperative 3D C-arm-based imaging confirming complete tumor lesion removal. Her pain was relieved immediately after the surgery, and there was no recurrence at 12 months of follow-up. This is the first case report of the surgical treatment of the osteoid osteoma in the talar neck with the combination methods of arthroscopy and 3D C-arm-based imaging.

Novel neutron sources at the Radiological Research Accelerator Facility

NASA Astrophysics Data System (ADS)

Xu, Y.; Garty, G.; Marino, S. A.; Massey, T. N.; Randers-Pehrson, G.; Johnson, G. W.; Brenner, D. J.

2012-03-01

Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a proton microbeam, impinging on a thin lithium target near the threshold of the 7Li(p,n)7Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.

Detection of terahertz radiation in metamaterials: giant plasmonic ratchet effect (Conference Presentation)

NASA Astrophysics Data System (ADS)

Rudin, Sergey; Rupper, Greg; Kachorovski, Valentin; Shur, Michael S.

2017-05-01

The electromagnetic wave impinging on the spatially modulated two-dimensional electron liquid (2DEL) induces a direct current (DC) when the wave amplitude modulated with the same wave vector as the 2DEL but is shifted in phase (the ratchet effect). The recent theory of this phenomenon predicted a dramatic enhancement at the plasmonic resonances and a non-trivial polarization dependence [1]. We will present the results of the numerical simulations using a hydrodynamic model exploring the helicity dependence of the DC current for silicon, InGaAs, and GaN metamaterial structures at cryogenic and room temperatures. In particular we will report on the effect of the DEL viscosity and explore the nonlinear effects at large amplitudes of the helical electromagnetic radiation impinging on the ratchet structures. We will then discuss the applications of the ratchet effect for terahertz metamaterials in order to realize ultra-sensitive terahertz (THz) radiation detectors, modulators, phase shifters, and delay lines with cross sections matching the terahertz wavelength and capable of determining the electromagnetic wave polarization and helicity. To this end, we propose and analyze the four contact ratchet devices capable of registering the two perpendicular components of the electric currents induced by the elliptically or circularly polarized radiation and analyze the load impedance effects in the structures optimized for the ratchet metamaterial THz components. The analysis is based on the hydrodynamic model suitable for the multi-gated semiconductor structures, coupled self-consistently with Poisson's equation for the electric potential. The model accounts for the effects of pressure gradients and 2DEL viscosity. Our numerical solutions are applicable to the wide ranges of electron mobility and terahertz power. [1] I. V. Rozhansky, V. Yu. Kachorovskii, and M. S. Shur, Helicity-Driven Ratchet Effect Enhanced by Plasmons, Phys. Rev. Lett. 114, 246601, 15 June 2015

Evaluation of an exercise concept focusing on eccentric strength training of the rotator cuff for patients with subacromial impingement syndrome.

PubMed

Bernhardsson, Susanne; Klintberg, Ingrid Hultenheim; Wendt, Gunilla Kjellby

2011-01-01

To evaluate the effect on pain intensity and function of an exercise concept focusing on specific eccentric strength training of the rotator cuff in patients with subacromial impingement syndrome. Single-subject research design with baseline and treatment phases (AB design). Home-based training programme supervised and supported by visits to physiotherapy clinic. Ten patients, mean (SD) age 54 (8.6) years, symptom duration 12 (9.1) months. Daily eccentric strengthening exercises of the rotator cuff during 12 weeks. Pain intensity, assessed with a visual analogue scale, and function, using the Patient-Specific Functional Scale. Shoulder function evaluated with the Constant score, and shoulder-related quality of life evaluated with the Western Ontario Rotator Cuff Index. Pain intensity decreased significantly in eight of the ten subjects. Function improved significantly in all ten subjects. Constant score increased in nine subjects and Western Ontario Rotator Cuff Index increased in seven subjects. Mean Constant score for the whole group increased significantly from 44 to 69 points (P = 0.008). Mean Western Ontario Rotator Cuff Index increased from 51 to 71% (P = 0.021). A 12-week eccentric strengthening programme targeting the rotator cuff and incorporating scapular control and correct movement pattern can be effective in decreasing pain and increasing function in patients with subacromial impingement syndrome. A randomized controlled trial is necessary to provide stronger evidence of the method.

Experimentally induced cam impingement in the sheep hip.

PubMed

Siebenrock, Klaus A; Fiechter, Ruth; Tannast, Moritz; Mamisch, Tallal C; von Rechenberg, Brigitte

2013-04-01

Sheep hips have a natural non-spherical femoral head similar to a cam-type deformity in human beings. By performing an intertrochanteric varus osteotomy, cam-type femoro-acetabular impingement (FAI) during flexion can be created. We tested the hypotheses that macroscopic lesions of the articular cartilage and an increased Mankin score (MS) can be reproduced by an experimentally induced cam-type FAI in this ovine in vivo model. Furthermore, we hypothesized that the MS increases with longer ambulatory periods. Sixteen sheep underwent unilateral intertrochanteric varus osteotomy of the hip with the non-operated hip as a control. Four sheep were sacrificed after 14, 22, 30, and 38-weeks postoperatively. We evaluated macroscopic chondrolabral alterations, and recorded the MS, based on histochemical staining, for each ambulatory period. A significantly higher prevalence of macroscopic chondrolabral lesions was found in the impingement zone of the operated hips. The MS was significantly higher in the acetabular/femoral cartilage of the operated hips. Furthermore, these scores increased as the length of the ambulatory period increased. Cam-type FAI can be induced in an ovine in vivo model. Localized chondrolabral degeneration of the hip, similar to that seen in humans (Tannast et al., Clin Orthop Relat Res 2008; 466: 273-280; Beck et al., J Bone Joint Surg Br 2005; 87: 1012-1018), can be reproduced. This experimental sheep model can be used to study cam-type FAI. Copyright © 2012 Orthopaedic Research Society.

Comparative performance of three sampling techniques to detect airborne Salmonella species in poultry farms.

PubMed

Adell, Elisa; Moset, Verónica; Zhao, Yang; Jiménez-Belenguer, Ana; Cerisuelo, Alba; Cambra-López, María

2014-01-01

Sampling techniques to detect airborne Salmonella species (spp.) in two pilot scale broiler houses were compared. Broilers were inoculated at seven days of age with a marked strain of Salmonella enteritidis. The rearing cycle lasted 42 days during the summer. Airborne Salmonella spp. were sampled weekly using impaction, gravitational settling, and impingement techniques. Additionally, Salmonella spp. were sampled on feeders, drinkers, walls, and in the litter. Environmental conditions (temperature, relative humidity, and airborne particulate matter (PM) concentration) were monitored during the rearing cycle. The presence of Salmonella spp. was determined by culture-dependent and molecular methods. No cultivable Salmonella spp. were recovered from the poultry houses' surfaces, the litter, or the air before inoculation. After inoculation, cultivable Salmonella spp. were recovered from the surfaces and in the litter. Airborne cultivable Salmonella spp. Were detected using impaction and gravitational settling one or two weeks after the detection of Salmonella spp. in the litter. No cultivable Salmonella spp. were recovered using impingement based on culture-dependent techniques. At low airborne concentrations, the use of impingement for the quantification or detection of cultivable airborne Salmonella spp. is not recommended. In these cases, a combination of culture-dependent and culture-independent methods is recommended. These data are valuable to improve current measures to control the transmission of pathogens in livestock environments and for optimising the sampling and detection of airborne Salmonella spp. in practical conditions.

Development of an improved model for runback water on aircraft surfaces

NASA Technical Reports Server (NTRS)

Al-Khalil, Kamel M.; Keith, Theo G., Jr.; De Witt, Kenneth J.

1992-01-01

A computer simulation for 'running wet' and evaporative aircraft anti-icing systems is developed. The model is based on the analysis of the liquid water film which forms in the regions of direct impingement and, then, breaks up near the impingement limits into rivulets. The wetness factor distribution resulting from the film breakup and the rivulet configuration on the surface are predicted using a stability analysis theory and the laws of mass energy conservation. The solid structure is modeled as a multiple layer wall. The anti-icing system modeled is of the thermal type utilizing hot air and/or electrical heating elements embedded within the wall layers. Experimental observations revealing some of the basic physics of the water flow on the surface are presented. Detailed qualitative documentation of the tests are given. Several numerical examples are considered, and the effect of some of the involved parameters on the system performance are investigated.

Imaging of femoroacetabular impingement-current concepts

PubMed Central

Albers, Christoph E.; Wambeek, Nicholas; Hanke, Markus S.; Schmaranzer, Florian; Prosser, Gareth H.; Yates, Piers J.

2016-01-01

Following the recognition of femoroacetabular impingement (FAI) as a clinical entity, diagnostic tools have continuously evolved. While the diagnosis of FAI is primarily made based on the patients’ history and clinical examination, imaging of FAI is indispensable. Routine diagnostic work-up consists of a set of plain radiographs, magnetic resonance imaging (MRI) and MR-arthrography. Recent advances in MRI technology include biochemically sensitive sequences bearing the potential to detect degenerative changes of the hip joint at an early stage prior to their appearance on conventional imaging modalities. Computed tomography may serve as an adjunct. Advantages of CT include superior bone to soft tissue contrast, making CT applicable for image-guiding software tools that allow evaluation of the underlying dynamic mechanisms causing FAI. This article provides a summary of current concepts of imaging in FAI and a review of the literature on recent advances, and their application to clinical practice. PMID:29632685

Flame structure of wall-impinging diesel fuel sprays injected by group-hole nozzles

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

Gao, Jian; Moon, Seoksu; Nishida, Keiya

This paper describes an investigation of the flame structure of wall-impinging diesel sprays injected by group-hole nozzles in a constant-volume combustion vessel at experimental conditions typical of a diesel engine. The particular emphasis was on the effect of the included angle between two orifices (0-15 deg. in current study) on the flame structure and combustion characteristics under various simulated engine load conditions. The laser absorption scattering (LAS) technique was applied to analyze the spray and mixture properties. Direct flame imaging and OH chemiluminescence imaging were utilized to quantify the ignition delay, flame geometrical parameters, and OH chemiluminescence intensity. The imagesmore » show that the asymmetric flame structure emerges in wall-impinging group-hole nozzle sprays as larger included angle and higher engine load conditions are applied, which is consistent with the spray shape observed by LAS. Compared to the base nozzle, group-hole nozzles with large included angles yield higher overall OH chemiluminescence intensity, wider flame area, and greater proportion of high OH intensity, implying the better fuel/air mixing and improved combustion characteristics. The advantages of group-hole nozzle are more pronounced under high load conditions. Based on the results, the feasibility of group-hole nozzle for practical direct injection diesel engines is also discussed. It is concluded that the asymmetric flame structure of a group-hole nozzle spray is favorable to reduce soot formation over wide engine loads. However, the hole configuration of the group-hole nozzle should be carefully considered so as to achieve proper air utilization in the combustion chamber. Stoichiometric diesel combustion is another promising application of group-hole nozzle. (author)« less

Jet stability and wall impingement flow field in a thermal striping experiment

DOE PAGES

Lomperski, S.; Obabko, A.; Merzari, E.; ...

2017-08-10

We present velocity and temperature field measurements for a 0.9 x 0.9 x 1.7 m glass tank in which two air jets at Re=10000 mix and impinge upon the lid at ambient temperature and pressure. Flow patterns are characterized across a 350 x 200 mm plane located 3 mm below the lid for two inlet geometries: 1) “extended”, in which inlet channels protrude above the tank base, and 2) “flush”, a flat base without protrusions. This minor geometry variation produced distinct changes in the lid flow field, appearing as three stagnant regions for the extended case and only one formore » flush. The dichotomy is attributed to system stability characteristics: jets are stable in the extended case and unstable for flush. In a separate set of nonisothermal tests, the impingement temperature field was measured for inlet temperature mismatches of 4 oC and jets near Re=10000. A 50 m-long fiber optic distributed temperature sensor positioned 2 mm below the lid measured at 1350 locations. Like the velocity fields, the temperature fields differ for the two inlet geometries: good thermal mixing for the flush case and subdued mixing for the extended case. Simulations with the spectral element code Nek5000 replicated the observed stability dichotomy, duplicating the number of stagnant regions observed in the experiment and matching their locations within ±10 mm. Simulation data suggests that flush case instability is due to interactions between jets and wall flows at the bottom of the tank. The clear flow dichotomy exhibited by this two-jet setup presents an unambiguous case to test the ability of CFD tools to predict subtle flow field changes driven by minor modifications in geometry in the context of thermal striping.« less

Jet stability and wall impingement flow field in a thermal striping experiment

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

Lomperski, S.; Obabko, A.; Merzari, E.

We present velocity and temperature field measurements for a 0.9 x 0.9 x 1.7 m glass tank in which two air jets at Re=10000 mix and impinge upon the lid at ambient temperature and pressure. Flow patterns are characterized across a 350 x 200 mm plane located 3 mm below the lid for two inlet geometries: 1) “extended”, in which inlet channels protrude above the tank base, and 2) “flush”, a flat base without protrusions. This minor geometry variation produced distinct changes in the lid flow field, appearing as three stagnant regions for the extended case and only one formore » flush. The dichotomy is attributed to system stability characteristics: jets are stable in the extended case and unstable for flush. In a separate set of nonisothermal tests, the impingement temperature field was measured for inlet temperature mismatches of 4 oC and jets near Re=10000. A 50 m-long fiber optic distributed temperature sensor positioned 2 mm below the lid measured at 1350 locations. Like the velocity fields, the temperature fields differ for the two inlet geometries: good thermal mixing for the flush case and subdued mixing for the extended case. Simulations with the spectral element code Nek5000 replicated the observed stability dichotomy, duplicating the number of stagnant regions observed in the experiment and matching their locations within ±10 mm. Simulation data suggests that flush case instability is due to interactions between jets and wall flows at the bottom of the tank. The clear flow dichotomy exhibited by this two-jet setup presents an unambiguous case to test the ability of CFD tools to predict subtle flow field changes driven by minor modifications in geometry in the context of thermal striping.« less

Observations on the use of membrane filtration and liquid impingement to collect airborne microorganisms in various atmospheric environments

USGS Publications Warehouse

Griffin, Dale W.; Gonzalez, C.; Teigell, N.; Petrosky, T.; Northup, D.E.; Lyles, M.

2011-01-01

The influence of sample-collection-time on the recovery of culturable airborne microorganisms using a low-flow-rate membrane-filtration unit and a high-flow-rate liquid impinger were investigated. Differences in recoveries were investigated in four different atmospheric environments, one mid-oceanic at an altitude of ~10.0 m, one on a mountain top at an altitude of ~3,000.0 m, one at ~1.0 m altitude in Tallahassee, Florida, and one at ~1.0 m above ground in a subterranean-cave. Regarding use of membrane filtration, a common trend was observed: the shorter the collection period, the higher the recovery of culturable bacteria and fungi. These data also demonstrated that lower culturable counts were common in the more remote mid-oceanic and mountain-top atmospheric environments with bacteria, fungi, and total numbers averaging (by sample time or method categories) <3.0 colony-forming units (CFU) m -3. At the Florida and subterranean sites, the lowest average count noted was 3.5 bacteria CFU m-3, and the highest averaged 140.4 total CFU m-3. When atmospheric temperature allowed use, the high-volume liquid impinger utilized in this study resulted in much higher recoveries, as much as 10?? greater in a number of the categories (bacterial, fungal, and total CFU). Together, these data illustrated that (1) the high-volume liquid impinger is clearly superior to membrane filtration for aeromicrobiology studies if start-up costs are not an issue and temperature permits use; (2) although membrane filtration is more cost friendly and has a 'typically' wider operational range, its limits include loss of cell viability with increased sample time and issues with effectively extracting nucleic acids for community-based analyses; (3) the ability to recover culturable microorganisms is limited in 'extreme' atmospheric environments and thus the use of a 'limited' methodology in these environments must be taken into account; and (4) the atmosphere culls, i.e., everything is not everywhere. ?? 2010 US Government.

Parametric study and optimization trends for the Von-Kármán-sodium dynamo experiment

NASA Astrophysics Data System (ADS)

Varela, J.

2018-05-01

We present magneto-hydrodynamic simulations of liquid sodium flow performed with the PLUTO compressible MHD code. We investigated the influence of the remanent magnetic field orientation and intensity, the impinging velocity field due to Ekman pumping as well as the impeller dimensions on the magnetic field collimation by helical flows in-between the impeller blades. For a simplified Cartesian geometry, we model the flow dynamics of a multi-blade impeller inspired by the Von-Kármán-Sodium experiment. This study shows that a remanent magnetic field oriented in the toroidal direction is the less efficient configuration to collimate the magnetic field, although if the radial or vertical components are not negligible, the collimation is significantly improved. As the intensity of the remanent magnetic field increases, the system magnetic energy becomes larger, but the magnetic field collimation efficiency remains the same, so the gain of magnetic energy is smaller as the remanent magnetic field intensity increases. The magnetic field collimation is modified if the impinging velocity field changes: the collimation is weaker if the impinging velocity increases from Γ = 0.8 to 0.9 and slightly larger if the impinging velocity decreases from Γ = 0.8 to 0.7. The analysis of the impeller dimensions points out that the most efficient configuration to collimate the magnetic field requires a ratio between the impeller blade height and the base longitude between 0.375 and 0.5. The largest enhancement of the hypothetical α2 dynamo loop, compared to the hypothetical Ω-α dynamo loop, is observed for the model that mimics the TM 73 impeller configuration rotating in the unscooping direction with a remanent magnetic field of 10-3 T orientated in the radial or vertical direction. The optimization trends obtained in the parametric analysis are also confirmed by simulations with a higher resolution and turbulence degree.

Optimization of a GO2/GH2 Impinging Injector Element

NASA Technical Reports Server (NTRS)

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

2001-01-01

An injector optimization methodology, method i, is used to investigate optimal design points for a gaseous oxygen/gaseous hydrogen (GO2/GH2) impinging injector element. The unlike impinging element, a fuel-oxidizer- fuel (F-O-F) triplet, is optimized in terms of design variables such as fuel pressure drop, (Delta)P(sub f), oxidizer pressure drop, (Delta)P(sub o), combustor length, L(sub comb), and impingement half-angle, alpha, 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 163 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. Three 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 which 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, specific variable weights are further increased to illustrate the high marginal cost of realizing the last increment of injector performance and thruster weight.

Three-dimensional numerical study of laminar confined slot jet impingement cooling using slurry of nano-encapsulated phase change material

NASA Astrophysics Data System (ADS)

Mohib Ur Rehman, M.; Qu, Z. G.; Fu, R. P.

2016-10-01

This Article presents a three dimensional numerical model investigating thermal performance and hydrodynamics features of the confined slot jet impingement using slurry of Nano Encapsulated Phase Change Material (NEPCM) as a coolant. The slurry is composed of water as a base fluid and n-octadecane NEPCM particles with mean diameter of 100nm suspended in it. A single phase fluid approach is employed to model the NEPCM slurry.The thermo physical properties of the NEPCM slurry are computed using modern approaches being proposed recently and governing equations are solved with a commercial Finite Volume based code. The effects of jet Reynolds number varying from 100 to 600 and particle volume fraction ranging from 0% to 28% are considered. The computed results are validated by comparing Nusselt number values at stagnation point with the previously published results with water as working fluid. It was found that adding NEPCM to the base fluid results with considerable amount of heat transfer enhancement.The highest values of heat transfer coefficients are observed at H/W=4 and Cm=0.28. However, due to the higher viscosity of slurry compared with the base fluid, the slurry can produce drastic increase in pressure drop of the system that increases with NEPCM particle loading and jet Reynolds number.

Impingement effect of service module reaction control system engine plumes. Results of service module reaction control system plume model force field application to an inflight Skylab mission proximity operation situation with the inflight Skylab response

NASA Technical Reports Server (NTRS)

Lobb, J. D., Jr.

1978-01-01

Plume impingement effects of the service module reaction control system thruster firings were studied to determine if previous flight experience would support the current plume impingement model for the orbiter reaction control system engines. The orbiter reaction control system is used for rotational and translational maneuvers such as those required during rendezvous, braking, docking, and station keeping. Therefore, an understanding of the characteristics and effects of the plume force fields generated by the reaction control system thruster firings were examined to develop the procedures for orbiter/payload proximity operations.

Impact of Drift on the Vehicle Liftoff Acoustic Environments

NASA Technical Reports Server (NTRS)

Kenny, Jeremy; Giacomoni, Clothilde

2016-01-01

During liftoff a vehicle can drift due to wind, nozzle gimbaling, fly away maneuver, etc... This drift can cause the exhaust plumes to impinge on the deck and cause the noise levels experienced by the vehicle to increase. A small increase in the plume impingement can have a dramatic effect on the noise levels when the vehicle is only a few nozzle diameters from the deck. As the vehicle lifts off the deck the increase in noise levels lessens as the plume impingement increases. Several scale model acoustic tests have been undertaken at Marshall Space Flight Center which had test cases that were used to define the relationship between drift and the noise levels experienced by the vehicle.

Experimental and computation study of liquid droplets impinging on an afterburner

NASA Astrophysics Data System (ADS)

Lavergne, G.; Hebrard, P.; Donnadille, Ph.

The actual development of three-dimensional computation codes of internal reactive flows in combustion chambers needs, for the liquid phase, accurate boundary conditions. A series of experiments was undertaken to identify and then to analyze physical phenomena occurring during spray transport and spray boundary interaction. The purpose of this paper is to investigate drop wall interaction, drop impingement, the liquid film, and the liquid flow rate captured by a flameholder. The experimental approach is divided in two parts: a parametric study on the captured fuel flow rate by a flameholder in an isothermal two-dimensional square facility, and a fundamental study of monosized droplet impingement on a hot plate to determine rebound criteria.

Computation of three-dimensional shock wave and boundary-layer interactions

NASA Technical Reports Server (NTRS)

Hung, C. M.

1985-01-01

Computations of the impingement of an oblique shock wave on a cylinder and a supersonic flow past a blunt fin mounted on a plate are used to study three dimensional shock wave and boundary layer interaction. In the impingement case, the problem of imposing a planar impinging shock as an outer boundary condition is discussed and the details of particle traces in windward and leeward symmetry planes and near the body surface are presented. In the blunt fin case, differences between two dimensional and three dimensional separation are discussed, and the existence of an unique high speed, low pressure region under the separated spiral vortex core is demonstrated. The accessibility of three dimensional separation is discussed.

Buffet Load Alleviation

NASA Technical Reports Server (NTRS)

Ryall, T. G.; Moses, R. W.; Hopkins, M. A.; Henderson, D.; Zimcik, D. G.; Nitzsche, F.

2004-01-01

High performance aircraft are, by their very nature, often required to undergo maneuvers involving high angles of attack. Under these conditions unsteady vortices emanating from the wing and the fuselage will impinge on the twin fins (required for directional stability) causing excessive buffet loads, in some circumstances, to be applied to the aircraft. These loads result in oscillatory stresses, which may cause significant amounts of fatigue damage. Active control is a possible solution to this important problem. A full-scale test was carried out on an F/A-18 fuselage and fins using piezoceramic actuators to control the vibrations. Buffet loads were simulated using very powerful electromagnetic shakers. The first phase of this test was concerned with the open loop system identification whereas the second stage involved implementing linear time invariant control laws. This paper looks at some of the problems encountered as well as the corresponding solutions and some results. It is expected that flight trials of a similar control system to alleviate buffet will occur as early as 2001.

Investigation of Jet Impingement Cooling Using High Prandtl Number Fluids and Ammonia for Military Applications

DTIC Science & Technology

2004-03-01

interesting application of liquid jets impinging over a surface is for the cooling of microelectronics. Wadsworth and Mudawar [29] performed an...and I. Mudawar , Cooling of a Multiple Electronic Module by Means of Confined Two-Dimensional Jets of Dielectric Liquid, Journal of Heat Transfer, vol

Division I Student-Athlete Degree Choice Assessment

ERIC Educational Resources Information Center

Terrell, Tony

2012-01-01

Though the NCAA has established rules that require student-athletes to complete their college degree in an expeditious manner, the 40/60/80% rule may impinge on student-athlete academic decisions (i.e., degree choice). Yet limited empirical data exist regarding the nature and prevalence of student-athlete degree impingement. The purpose of this…

Nozzle cavity impingement/area reduction insert

DOEpatents

Yu, Yufeng Phillip; Itzel, Gary Michael; Osgood, Sarah Jane

2002-01-01

A turbine vane segment is provided that has inner and outer walls spaced from one another, a vane extending between the inner and outer walls and having leading and trailing edges and pressure and suction sides, the vane including discrete leading edge, intermediate, aft and trailing edge cavities between the leading and trailing edges and extending lengthwise of the vane for flowing a cooling medium; and an insert sleeve within at least one of the cavities and spaced from interior wall surfaces thereof. The insert sleeve has an inlet for flowing the cooling medium into the insert sleeve and has impingement holes defined in first and second walls thereof that respectively face the pressure and suction sides of the vane. The impingement holes of at least one of those first and second walls are defined along substantially only a first, upstream portion thereof, whereby the cooling flow is predominantly impingement cooling along a first region of the insert wall corresponding to the first, upstream portion and the cooling flow is predominantly convective cooling along a second region corresponding to a second, downstream portion of the at least one wall of the insert sleeve.

Heat transfer characteristics within an array of impinging jets. Effects of crossflow temperature relative to jet temperature

NASA Technical Reports Server (NTRS)

Florschuetz, L. W.; Su, C. C.

1985-01-01

Spanwise average heat fluxes, resolved in the streamwise direction to one stream-wise hole spacing were measured for two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate. The jet flow, after impingement, was constrained to exit in a single direction along the channel formed by the jet orifice plate and heat transfer surface. The crossflow originated from the jets following impingement and an initial crossflow was present that approached the array through an upstream extension of the channel. The regional average heat fluxes are considered as a function of parameters associated with corresponding individual spanwise rows within the array. A linear superposition model was employed to formulate appropriate governing parameters for the individual row domain. The effects of flow history upstream of an individual row domain are also considered. The results are formulated in terms of individual spanwise row parameters. A corresponding set of streamwise resolved heat transfer characteristics formulated in terms of flow and geometric parameters characterizing the overall arrays is described.

Correlations Among Ice Measurements, Impingement Rates Icing Conditions, and Drag Coefficients for Unswept NACA 65A004 Airfoil

NASA Technical Reports Server (NTRS)

Gray, Vernon H.

1958-01-01

An empirical relation has been obtained by which the change in drag coefficient caused by ice formations on an unswept NACA 65AO04 airfoil section can be determined from the following icing and operating conditions: icing time, airspeed, air total temperature, liquid-water content, cloud droplet impingement efficiencies, airfoil chord length, and angles of attack. The correlation was obtained by use of measured ice heights and ice angles. These measurements were obtained from a variety of ice formations, which were carefully photographed, cross-sectioned, and weighed. Ice weights increased at a constant rate with icing time in a rime icing condition and at progressively increasing rates in glaze icing conditions. Initial rates of ice collection agreed reasonably well with values predicted from droplet impingement data. Experimental droplet impingement rates obtained on this airfoil section agreed with previous theoretical calculations for angles of attack of 40 or less. Disagreement at higher angles of attack was attributed to flow separation from the upper surface of the experimental airfoil model.

Particle Ejection and Levitation Technology (PELT)

NASA Technical Reports Server (NTRS)

2008-01-01

Each of the six Apollo landers touched down at unique sites on the lunar surface. Aside from the Apollo 12 landing site located 180 meters from the Surveyor III lander, plume impingement effects on ground hardware during the landings were not a problem. The planned return to the Moon requires numerous landings at the same site. Since the top few centimeters of lunar soil are loosely packed regolith, plume impingement from the lander will eject the granular material at high velocities. A picture shows what the astronauts viewed from the window of the Apollo 14 lander. There was tremendous dust excavation beneath the vehicle. With high-vacuum conditions on the Moon (10 (exp -14) to 10 (exp -12) torr), motion of all particles is completely ballistic. Estimates derived from damage to Surveyor III caused by the Apollo 12 lander show that the speed of the ejected regolith particles varies from 100 m/s to 2,000 m/s. It is imperative to understand the physics of plume impingement to safely design landing sites for future Moon missions. Aerospace scientists and engineers have examined and analyzed images from Apollo video extensively in an effort to determine the theoretical effects of rocket exhaust impingement. KSC has joined the University of Central Florida (UCF) to develop an instrument that will measure the 3-D vector of dust flow caused by plume impingement during descent of landers. The data collected from the instrument will augment the theoretical studies and analysis of the Apollo videos.

Pelvic posture and kinematics in femoroacetabular impingement: a systematic review.

PubMed

Pierannunzii, Luca

2017-09-01

Pelvic posture and kinematics influence acetabular orientation and are therefore expected to be involved in the pathomechanics of femoroacetabular impingement (FAI). This systematic review aims to determine whether FAI patients show pelvic postures or patterns of motion contributing to impingement or, conversely, develop compensatory postures and patterns of motion preventing it. PubMed/MEDLINE, Embase, Google Scholar and the Cochrane Library were systematically searched to find all the studies that measured pelvic positional and/or kinematic data in humans (patients or cadaveric specimens) affected by FAI. Twelve items were selected and grouped according to the main field of investigation. No quantitative data synthesis was allowed due to methodological heterogeneity. Pelvic posture and kinematics seem to play a relevant role in FAI. The patients, especially if symptomatic, show a paradoxical lack of pelvic back tilt in standing hip flexions, i.e., in squatting, that enhances femoroacetabular engagement. Such an aberrant pattern might depend on a lower pelvic incidence. On the contrary, active hip flexion in decubitus elicits a compensatory, more pronounced back tilt to facilitate hip flexion without impingement. Stair climbing shows a compensatory pattern of augmented pelvic axial rotation and augmented peak forward tilt to reduce painful hip motions, namely internal rotation and extension. In FAI patients, pelvic posture and kinematics are sometimes an expression of compensatory mechanisms developed to reduce pain and discomfort, and sometimes an expression of paradoxical responses that further enhance the impingement pathomechanism. IV.

Ultrasound in Total Hip Replacement: Value of Anterior Acetabular Cup Visibility and Contact With the Iliopsoas Tendon.

PubMed

Guillin, Raphaël; Bertaud, Valérie; Garetier, Marc; Fantino, Olivier; Polard, Jean-Louis; Lambotte, Jean-Christophe

2018-06-01

To assess visibility of the acetabular cup in total hip replacement and to determine the value of direct and indirect signs of iliopsoas impingement syndrome with ultrasound. Ultrasound examinations were performed by a single operator in 17 patients with iliopsoas impingement syndrome and 48 control patients. Cup visibility, contact between the cup and psoas tendon, and the presence of indirect signs of iliopsoas impingement syndrome were investigated in all patients. When the acetabular cup was visible, its size and position in relation to the psoas tendon were recorded. Anterior cup visibility (P = .03), contact with the psoas tendon (P < .001), psoas tendinopathy (P = .02), and iliopsoas bursitis (P < .001) were significantly associated with iliopsoas impingement syndrome, the latter reported with specificity of 100%. In the sagittal plane at the level of the psoas tendon, a maximum sagittal length of greater than 5 mm and a posteroanterior cup shift of 3 mm or greater yielded respective sensitivities of 82% and 59% and specificities of 81% and 100%. When iliopsoas impingement syndrome is clinically suspected, the presence of iliopsoas bursitis or a posteroanterior cup shift of greater than 3 mm under the psoas tendon serve to confirm the diagnosis. In the absence of these conditions, a therapeutic test may be necessary because of the incomplete, albeit high, specificity of other signs. © 2017 by the American Institute of Ultrasound in Medicine.

The Use of an Orthopaedic Rating System in Major League Baseball

PubMed Central

McGahan, Patrick J.; Fronek, Jan; Hoenecke, Heinz R.; Keefe, Daniel

2014-01-01

Background: Although the majority of Major League Baseball teams use an orthopaedic rating system to evaluate draft picks, little has been published on the topic. Hypothesis: Our goal was to assess the attitudes among Major League Baseball physicians regarding 3 common diagnoses in pitching prospects, through the use of an orthopaedic rating system. Our hypothesis was that the assigned orthopaedic grades would vary among physicians, diagnoses, and operative-versus-nonoperative and recent-versus-past treatment. Study Design: Survey. Level of Evidence: Level 4. Methods: A survey in the form of 12 clinical vignettes was used to query Major League Baseball physicians regarding ulnar collateral ligament (UCL) injuries, type II superior labrum anterior posterior (SLAP) tears, and internal impingement. Respondents graded draft picks using an orthopaedic rating system. The vignettes covered both operative and nonoperative and recent and past treatment (successful return to pitching for 1 year). Results: The orthopaedic grades assigned by respondents were as follows (minimal, moderate, severe risk): past UCL reconstruction (73%, 27%, 0%), recent UCL reconstruction (19%, 77%, 4%), past UCL strain (28%, 60%, 12%), recent UCL strain (0%, 48%, 52%), past SLAP repair (52%, 48%, 0%), recent SLAP repair (4%, 64%, 32%), past SLAP nonoperative (28%, 60%, 12%), recent SLAP nonoperative (0%, 36%, 64%), past internal impingement operative (24%, 68%, 8%), recent internal impingement operative (8%, 32%, 60%), past internal impingement nonoperative (24%, 68%, 8%), and recent internal impingement nonoperative (4%, 48%, 44%). Conclusion: Team physicians are optimistic regarding the outcome of UCL reconstruction. In contrast, UCL strains, type II SLAP lesions, and internal impingement carry a guarded prognosis. For all diagnoses, regardless of treatment, the prognosis improved if a player returned to pitching for 1 full season. Clinical Relevance: This study represents a first step toward developing a standardized orthopaedic rating system that will facilitate more accurate player assessment and clearer communication among physicians. PMID:25177423

Avulsion of the direct head of rectus femoris following arthroscopic subspine impingement resection: a case report

PubMed Central

Devitt, Brian M.; Smith, Bjorn; Stapf, Robert; O’Donnell, John M.

2016-01-01

Arthroscopic resection of the anterior inferior iliac spine (AIIS) for subspine impingement has become a relatively common procedure. The AIIS is the origin of the direct head of rectus femoris (dhRF). Previous studies have reported that removal of the contributing portion of the AIIS causing impingement is unlikely to weaken the attachment of the dhRF. The purpose of this article is to report a case of avulsion of the dhRF, following revision hip arthroscopy for the treatment of subspine impingement. A 23-year-old professional footballer underwent revision left hip arthroscopy for the treatment of subspine impingement. 5-mm of bone was resected inferior to the AIIS. Two-weeks post-operatively, he presented with sudden onset, severe left anterior thigh pain following a fall and hyperextension of his left hip. The patient felt a pop over the anterior aspect of his hip. He noticed immediate swelling, severe pain and stiffness. Examination revealed diffuse swelling, 4/5-power on straight-leg-raise, focal tenderness over the AIIS but no palpable gap. MRI confirmed the clinical suspicion of a dhRF avulsion. Given the minimal loss of power and the lack of significant retraction, the patient was treated conservatively. He was instructed to avoid excessive hip extension. He returned to full participation at 3-months. This article highlights a case of avulsion of the dhRF due to a hyperextension injury of the hip following arthroscopic resection of subspinal impingement, a previously unreported complication. Resection of soft and bone from the AIIS may weaken the insertion of the dhRF. Care should be taken during post-operative rehabilitation to avoid trauma and excessive forces on the dhRF tendon, which may lead to rupture. Rehabilitation should be focused on range of motion of the hip. PMID:27026819

Avulsion of the direct head of rectus femoris following arthroscopic subspine impingement resection: a case report.

PubMed

Devitt, Brian M; Smith, Bjorn; Stapf, Robert; O'Donnell, John M

2016-04-01

Arthroscopic resection of the anterior inferior iliac spine (AIIS) for subspine impingement has become a relatively common procedure. The AIIS is the origin of the direct head of rectus femoris (dhRF). Previous studies have reported that removal of the contributing portion of the AIIS causing impingement is unlikely to weaken the attachment of the dhRF. The purpose of this article is to report a case of avulsion of the dhRF, following revision hip arthroscopy for the treatment of subspine impingement. A 23-year-old professional footballer underwent revision left hip arthroscopy for the treatment of subspine impingement. 5-mm of bone was resected inferior to the AIIS. Two-weeks post-operatively, he presented with sudden onset, severe left anterior thigh pain following a fall and hyperextension of his left hip. The patient felt a pop over the anterior aspect of his hip. He noticed immediate swelling, severe pain and stiffness. Examination revealed diffuse swelling, 4/5-power on straight-leg-raise, focal tenderness over the AIIS but no palpable gap. MRI confirmed the clinical suspicion of a dhRF avulsion. Given the minimal loss of power and the lack of significant retraction, the patient was treated conservatively. He was instructed to avoid excessive hip extension. He returned to full participation at 3-months. This article highlights a case of avulsion of the dhRF due to a hyperextension injury of the hip following arthroscopic resection of subspinal impingement, a previously unreported complication. Resection of soft and bone from the AIIS may weaken the insertion of the dhRF. Care should be taken during post-operative rehabilitation to avoid trauma and excessive forces on the dhRF tendon, which may lead to rupture. Rehabilitation should be focused on range of motion of the hip.

Surgical hip dislocation for treatment of cam femoroacetabular impingement

PubMed Central

Chaudhary, Milind M; Chaudhary, Ishani M; Vikas, KN; KoKo, Aung; Zaw, Than; Siddhartha, A

2015-01-01

Background: Cam femoroacetabular impingement is caused by a misshapen femoral head with a reduced head neck offset, commonly in the anterolateral quadrant. Friction in flexion, adduction and internal rotation causes limitation of the hip movements and pain progressively leading to labral and chondral damage and osteoarthritis. Surgical hip dislocation described by Ganz permits full exposure of the hip without damaging its blood supply. An osteochondroplasty removes the bump at the femoral head neck junction to recreate the offset for impingement free movement. Materials and Methods: Sixteen patients underwent surgery with surgical hip dislocation for the treatment of cam femoroacetabular impingement by open osteochondroplasty over last 6 years. Eight patients suffered from sequelae of avascular necrosis (AVN). Three had a painful dysplastic hip. Two had sequelae of Perthes disease. Three had combined cam and pincer impingement caused by retroversion of acetabulum. All patients were operated by the trochanteric flip osteotomy with attachments of gluteus medius and vastus lateralis, dissection was between the piriformis and gluteus minimus preserving the external rotators. Z-shaped capsular incision and dislocation of the hip was done in external rotation. Three cases also had subtrochanteric osteotomy. Two cases of AVN also had an intraarticular femoral head reshaping osteotomy. Results: Goals of treatment were achieved in all patients. No AVN was detected after a 6 month followup. There were no trochanteric nonunions. Hip range of motion improved in all and Harris hip score improved significantly in 15 of 16 cases. Mean alpha angle reduced from 86.13° (range 66°–108°) to 46.35° (range 39°–58°). Conclusion: Cam femoroacetabular Impingement causing pain and limitation of hip movements was treated by open osteochondroplasty after surgical hip dislocation. This reduced pain, improved hip motion and gave good to excellent results in the short term. PMID:26538754

Experimental studies of hypersonic shock-wave boundary-layer interactions

NASA Technical Reports Server (NTRS)

Lu, Frank K.

1992-01-01

Two classes of shock-wave boundary-layer interactions were studied experimentally in a shock tunnel in which a low Reynolds number, turbulent flow at Mach 8 was developed on a cold, flat test surface. The two classes of interactions were: (1) a swept interaction generated by a wedge ('fin') mounted perpendicularly on the flat plate; and (2) a two-dimensional, unseparated interaction induced by a shock impinging near an expansion corner. The swept interaction, with wedge angles of 5-20 degrees, was separated and there was also indication that the strongest interactions prossessed secondary separation zones. The interaction spread out extensively from the inviscid shock location although no indication of quasi-conical symmetry was evident. The surface pressure from the upstream influence to the inviscid shock was relatively low compared to the inviscid downstream value but it rose rapidly past the inviscid shock location. However, the surface pressure did not reach the downstream inviscid value and reasons were proposed for this anomalous behavior compared to strongly separated, supersonic interactions. The second class of interactions involved weak shocks impinging near small expansion corners. As a prelude to studying this interaction, a hypersonic similarity parameter was identified for the pure, expansion corner flow. The expansion corner severely damped out surface pressure fluctuations. When a shock impinged upstream of the corner, no significant changes to the surface pressure were found as compared to the case when the shock impinged on a flat plate. But, when the shock impinged downstream of the corner, a close coupling existed between the two wave systems, unlike the supersonic case. This close coupling modified the upstream influence. Regardless of whether the shock impinged ahead or behind the corner, the downstream region was affected by the close coupling between the shock and the expansion. Not only was the mean pressure distribution modified but the unsteadiness in the surface pressure was reduced compared to the flat-plate case.

Quantifying resistances across nanoscale low- and high-angle interspherulite boundaries in solution-processed organic semiconductor thin films.

PubMed

Lee, Stephanie S; Mativetsky, Jeffrey M; Loth, Marsha A; Anthony, John E; Loo, Yueh-Lin

2012-11-27

The nanoscale boundaries formed when neighboring spherulites impinge in polycrystalline, solution-processed organic semiconductor thin films act as bottlenecks to charge transport, significantly reducing organic thin-film transistor mobility in devices comprising spherulitic thin films as the active layers. These interspherulite boundaries (ISBs) are structurally complex, with varying angles of molecular orientation mismatch along their lengths. We have successfully engineered exclusively low- and exclusively high-angle ISBs to elucidate how the angle of molecular orientation mismatch at ISBs affects their resistivities in triethylsilylethynyl anthradithiophene thin films. Conductive AFM and four-probe measurements reveal that current flow is unaffected by the presence of low-angle ISBs, whereas current flow is significantly disrupted across high-angle ISBs. In the latter case, we estimate the resistivity to be 22 MΩμm(2)/width of the ISB, only less than a quarter of the resistivity measured across low-angle grain boundaries in thermally evaporated sexithiophene thin films. This discrepancy in resistivities across ISBs in solution-processed organic semiconductor thin films and grain boundaries in thermally evaporated organic semiconductor thin films likely arises from inherent differences in the nature of film formation in the respective systems.

The 0.040-scale space shuttle orbiter base heating model tests in the Lewis Research Center space power facility

NASA Technical Reports Server (NTRS)

Dezelick, R. A.

1976-01-01

Space shuttle base heating tests were conducted using a 0.040-scale model in the Plum Brook Space Power Facility of The NASA Lewis Research Center. The tests measured heat transfer rates, pressure distributions, and gas recovery temperatures on the orbiter vehicle 2A base configuration resulting from engine plume impingement. One hundred and sixty-eight hydrogen-oxygen engine firings were made at simulated flight altitudes ranging from 120,000 to 360,000 feet.

Development of a micro-XRF system for biological samples based on proton-induced quasimonochromatic X-rays

NASA Astrophysics Data System (ADS)

Ploykrachang, K.; Hasegawa, J.; Kondo, K.; Fukuda, H.; Oguri, Y.

2014-07-01

We have developed a micro-XRF system based on a proton-induced quasimonochromatic X-ray (QMXR) microbeam for in vivo measurement of biological samples. A 2.5-MeV proton beam impinged normally on a Cu foil target that was slightly thicker than the proton range. The emitted QMXR behind the Cu target was focused with a polycapillary X-ray half lens. For application to analysis of wet or aquatic samples, we prepared a QMXR beam with an incident angle of 45° with respect to the horizontal plane by using a dipole magnet in order to bend the primary proton beam downward by 45°. The focal spot size of the QMXR microbeam on a horizontal sample surface was evaluated to be 250 × 350 μm by a wire scanning method. A microscope camera with a long working distance was installed perpendicular to the sample surface to identify the analyzed position on the sample. The fluorescent radiation from the sample was collected by a Si-PIN photodiode X-ray detector. Using the setup above, we were able to successfully measure the accumulation and distribution of Co in the leaves of a free-floating aquatic plant on a dilute Co solution surface.

Summer Reading 2008: Recent Books on ICT & Education

ERIC Educational Resources Information Center

Perkins, Ross, Comp.

2008-01-01

Though many U.S.-based distance programs were originally developed for domestic use, a number of programs are expanding their offerings to students living outside North America. As a result, a number of contextual factors impinge upon the design of classes, or at least in the way that content is represented. Additionally, there is a need to make…

Reverse laser drilling

NASA Technical Reports Server (NTRS)

Anthony, Thomas R. (Inventor)

1984-01-01

This invention provides a method for laser drilling small diameter, closely-spaced, and accurately located holes in a body of material which is transparent or substantially transparent to the laser radiation employed whereby the holes are drilled through the thickness of the body from the surface opposite to that on which the laser beam impinges to the surface of laser beam impingement.

40 CFR 63.457 - Test methods and procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... combustion device that is designed and operated as specified in § 63.443(d)(3) or (d)(4). (b) Vent sampling... milliliter (ml) capacity midget impingers shall be connected in series to the sampling line. The impingers..., recording the time. End the sampling after 60 minutes, or after yellow color is observed in the second in...

40 CFR 86.1243-96 - Calculations; evaporative emissions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the measured volume is determined and used for all vehicles tested by that manufacturer. (E) r=FID response factor to methanol. (F) PB=Barometric pressure, in Hg (Kpa). (G) T=Enclosure temperature, °R(°K... sampling, in. Hg. (I) i=Initial sample. (J) f=Final sample. (K) 1=First impinger. (L) 2=Second impinger. (M...

40 CFR 86.1243-96 - Calculations; evaporative emissions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... the measured volume is determined and used for all vehicles tested by that manufacturer. (E) r=FID response factor to methanol. (F) PB=Barometric pressure, in Hg (Kpa). (G) T=Enclosure temperature, °R(°K... sampling, in. Hg. (I) i=Initial sample. (J) f=Final sample. (K) 1=First impinger. (L) 2=Second impinger. (M...

40 CFR 86.1243-96 - Calculations; evaporative emissions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the measured volume is determined and used for all vehicles tested by that manufacturer. (E) r=FID response factor to methanol. (F) PB=Barometric pressure, in Hg (Kpa). (G) T=Enclosure temperature, °R(°K... sampling, in. Hg. (I) i=Initial sample. (J) f=Final sample. (K) 1=First impinger. (L) 2=Second impinger. (M...

Impingement heat transfer from turbulent air jets to flat plates: A literature survey

NASA Technical Reports Server (NTRS)

Livingood, J. N. B.; Hrycak, P.

1973-01-01

Heat transfer characteristics of single and multiple turbulent air jets impinging on flat surfaces have been studied by many investigators. Results of many of these studies are summarized. Suggested correlations for use in the design of cooled turbine blades are noted, and areas where further research would be advisable are identified.

Experimental Study of Structure of Low Density Jet Impinging on Tilt Plate by LIF and PSP

NASA Astrophysics Data System (ADS)

Fujimoto, Tetsuo; Sato, Kimihiko; Naniwa, Shuji; Inoue, Tomoyuki; Nakashima, Kouji

2000-07-01

The structure of low density jets impinging on a tilt plate is studied by hybrid use of LIF and PSP. The jet through an orifice flows into low pressure chamber of 0.12 Torr and impinges on to the tilt plate with angle from jet axis 45 or 60 or 90. A horizontal plane including the jet axis is visualized by LIF of seeded Iodine molecule, scanning a laser beam along the jet axis. On the other hand, the pressure distribution on the tilt plate is visualized by PSP. In comparing the results of the two methods, the shock wave system is analyzed. Deformation of the Mach disk and the barrel shock are confirmed.

Laminar and turbulent flow computations of Type 4 shock-shock interference aerothermal loads using unstructured grids

NASA Technical Reports Server (NTRS)

Vemaganti, Gururaja R.

1994-01-01

This report presents computations for the Type 4 shock-shock interference flow under laminar and turbulent conditions using unstructured grids. Mesh adaptation was accomplished by remeshing, refinement, and mesh movement. Two two-equation turbulence models were used to analyze turbulent flows. The mean flow governing equations and the turbulence governing equations are solved in a coupled manner. The solution algorithm and the details pertaining to its implementation on unstructured grids are described. Computations were performed at two different freestream Reynolds numbers at a freestream Mach number of 11. Effects of the variation in the impinging shock location are studied. The comparison of the results in terms of wall heat flux and wall pressure distributions is presented.

Anomalous incident-angle and elliptical-polarization rotation of an elastically refracted P-wave

NASA Astrophysics Data System (ADS)

Fa, Lin; Fa, Yuxiao; Zhang, Yandong; Ding, Pengfei; Gong, Jiamin; Li, Guohui; Li, Lijun; Tang, Shaojie; Zhao, Meishan

2015-08-01

We report a newly discovered anomalous incident-angle of an elastically refracted P-wave, arising from a P-wave impinging on an interface between two VTI media with strong anisotropy. This anomalous incident-angle is found to be located in the post-critical incident-angle region corresponding to a refracted P-wave. Invoking Snell’s law for a refracted P-wave provides two distinctive solutions before and after the anomalous incident-angle. For an inhomogeneously refracted and elliptically polarized P-wave at the anomalous incident-angle, its rotational direction experiences an acute variation, from left-hand elliptical to right-hand elliptical polarization. The new findings provide us an enhanced understanding of acoustical-wave scattering and lead potentially to widespread and novel applications.

Implementation of Combined Feather and Surface-Normal Ice Growth Models in LEWICE/X

NASA Technical Reports Server (NTRS)

Velazquez, M. T.; Hansman, R. J., Jr.

1995-01-01

Experimental observations have shown that discrete rime ice growths called feathers, which grow in approximately the direction of water droplet impingement, play an important role in the growth of ice on accreting surfaces for some thermodynamic conditions. An improved physical model of ice accretion has been implemented in the LEWICE 2D panel-based ice accretion code maintained by the NASA Lewis Research Center. The LEWICE/X model of ice accretion explicitly simulates regions of feather growth within the framework of the LEWICE model. Water droplets impinging on an accreting surface are withheld from the normal LEWICE mass/energy balance and handled in a separate routine; ice growth resulting from these droplets is performed with enhanced convective heat transfer approximately along droplet impingement directions. An independent underlying ice shape is grown along surface normals using the unmodified LEWICE method. The resulting dual-surface ice shape models roughness-induced feather growth observed in icing wind tunnel tests. Experiments indicate that the exact direction of feather growth is dependent on external conditions. Data is presented to support a linear variation of growth direction with temperature and cloud water content. Test runs of LEWICE/X indicate that the sizes of surface regions containing feathers are influenced by initial roughness element height. This suggests that a previous argument that feather region size is determined by boundary layer transition may be incorrect. Simulation results for two typical test cases give improved shape agreement over unmodified LEWICE.

Femoroacetabular impingement and osteoarthritis of the hip.

PubMed

Zhang, Charlie; Li, Linda; Forster, Bruce B; Kopec, Jacek A; Ratzlaff, Charles; Halai, Lalji; Cibere, Jolanda; Esdaile, John M

2015-12-01

To outline the clinical presentation, physical examination findings, diagnostic criteria, and management options of femoroacetabular impingement (FAI). PubMed was searched for relevant articles regarding the pathogenesis, diagnosis, treatment, and prognosis of FAI. In recent years, FAI has been increasingly recognized as a potential precursor and an important contributor to hip pain in the adult population and idiopathic hip osteoarthritis later in life. Femoroacetabular impingement is a collection of bony morphologic abnormalities of the hip joint that result in abnormal contact during motion. Cam-type FAI relates to a non-spherical osseous prominence of the proximal femoral neck or head-neck junction. Pincer-type FAI relates to excessive acetabular coverage over the femoral head, which can occur owing to several morphologic variants. Patients with FAI present with chronic, deep, or aching anterior groin pain most commonly in the sitting position, or during or after activity. Patients might also experience occasional sharp pains during activity. A thorough history should be taken that includes incidence of trauma and exercise frequency. A physical examination should be performed that includes a full hip, low back, and abdominal examination to assess for alternate causes of anterior groin pain. Diagnosis of FAI should be confirmed with radiography. Femoroacetabular impingement can be managed conservatively with rest, modification of activities, medications, and physiotherapy, or it can be treated surgically. Femoroacetabular impingement is an important cause of anterior groin pain. Early recognition and intervention by the primary care provider might be critical to alleviating morbidity and preventing FAI progression. Copyright© the College of Family Physicians of Canada.

Preoperative physical examination and imaging of femoroacetabular impingement prior to hip arthroscopy-a systematic review.

PubMed

Haldane, Chloe E; Ekhtiari, Seper; de Sa, Darren; Simunovic, Nicole; Ayeni, Olufemi R

2017-08-01

The purpose of this systematic review is to report current preoperative assessment for femoroacetabular impingement (FAI) including physical examination and imaging modalities prior to hip arthroscopy, and report current imaging measures used in the diagnosis of FAI. The electronic databases MEDLINE, EMBASE and PubMed were searched and screened in duplicate for relevant studies. Data regarding patient demographics, non-operative treatment, preoperative assessment including physical examination and imaging prior to hip arthroscopy were abstracted. Study quality was assessed in duplicate using the Methodological Index for Non-Randomized Studies criteria. Sixty-eight studies of fair quality evidence that involved a total of 5125 patients (5400 hips) were included. In total, 56% of all patients were male and mean age was 36 years (SD ± 10.0). Within physical examination, FADIR impingement testing was reported in 57% of patients. All included studies reported plain radiographic imaging as a component of preoperative assessment with anterior-posterior pelvis view being the most commonly reported view, followed by the cross-table lateral and Dunn views. Magnetic resonance imaging was obtained for 52% of included patients and computed tomography for 26% of patients. The most commonly reported measure within imaging for the diagnosis of cam type impingement was alpha angle (66%), whereas for pincer type impingement, the cross-over sign (48%) was most reported. Preoperative assessment is underreported in the FAI literature. Improved reporting is warranted to develop a more consistent and validated diagnostic algorithm for FAI to enhance patient selection. Level of evidence : Level IV, Systematic Review of Level I-IV Studies.

Preoperative physical examination and imaging of femoroacetabular impingement prior to hip arthroscopy—a systematic review

PubMed Central

Haldane, Chloe E.; Ekhtiari, Seper; de SA, Darren; Simunovic, Nicole

2017-01-01

Abstract The purpose of this systematic review is to report current preoperative assessment for femoroacetabular impingement (FAI) including physical examination and imaging modalities prior to hip arthroscopy, and report current imaging measures used in the diagnosis of FAI. The electronic databases MEDLINE, EMBASE and PubMed were searched and screened in duplicate for relevant studies. Data regarding patient demographics, non-operative treatment, preoperative assessment including physical examination and imaging prior to hip arthroscopy were abstracted. Study quality was assessed in duplicate using the Methodological Index for Non-Randomized Studies criteria. Sixty-eight studies of fair quality evidence that involved a total of 5125 patients (5400 hips) were included. In total, 56% of all patients were male and mean age was 36 years (SD ± 10.0). Within physical examination, FADIR impingement testing was reported in 57% of patients. All included studies reported plain radiographic imaging as a component of preoperative assessment with anterior–posterior pelvis view being the most commonly reported view, followed by the cross-table lateral and Dunn views. Magnetic resonance imaging was obtained for 52% of included patients and computed tomography for 26% of patients. The most commonly reported measure within imaging for the diagnosis of cam type impingement was alpha angle (66%), whereas for pincer type impingement, the cross-over sign (48%) was most reported. Preoperative assessment is underreported in the FAI literature. Improved reporting is warranted to develop a more consistent and validated diagnostic algorithm for FAI to enhance patient selection. Level of evidence: Level IV, Systematic Review of Level I–IV Studies. PMID:28948032

Femoroacetabular impingement and osteoarthritis of the hip

PubMed Central

Zhang, Charlie; Li, Linda; Forster, Bruce B.; Kopec, Jacek A.; Ratzlaff, Charles; Halai, Lalji; Cibere, Jolanda; Esdaile, John M.

2015-01-01

Objective To outline the clinical presentation, physical examination findings, diagnostic criteria, and management options of femoroacetabular impingement (FAI). Sources of information PubMed was searched for relevant articles regarding the pathogenesis, diagnosis, treatment, and prognosis of FAI. Main message In recent years, FAI has been increasingly recognized as a potential precursor and an important contributor to hip pain in the adult population and idiopathic hip osteoarthritis later in life. Femoroacetabular impingement is a collection of bony morphologic abnormalities of the hip joint that result in abnormal contact during motion. Cam-type FAI relates to a non-spherical osseous prominence of the proximal femoral neck or head-neck junction. Pincer-type FAI relates to excessive acetabular coverage over the femoral head, which can occur owing to several morphologic variants. Patients with FAI present with chronic, deep, or aching anterior groin pain most commonly in the sitting position, or during or after activity. Patients might also experience occasional sharp pains during activity. A thorough history should be taken that includes incidence of trauma and exercise frequency. A physical examination should be performed that includes a full hip, low back, and abdominal examination to assess for alternate causes of anterior groin pain. Diagnosis of FAI should be confirmed with radiography. Femoroacetabular impingement can be managed conservatively with rest, modification of activities, medications, and physiotherapy, or it can be treated surgically. Conclusion Femoroacetabular impingement is an important cause of anterior groin pain. Early recognition and intervention by the primary care provider might be critical to alleviating morbidity and preventing FAI progression. PMID:26668284

Subacromial impingement syndrome: An electromyographic study of shoulder girdle muscle fatigue.

PubMed

Alizadehkhaiyat, Omid; Roebuck, Margaret M; Makki, Ahmed T; Frostick, Simon P

2018-02-01

Muscle fatigue affecting glenohumeral and/or scapular muscles is suggested as one of the contributing factors to the development of subacromial impingement syndrome (SAIS). Nonetheless, the fatigability of shoulder girdle muscles in association with the pathomechanics of SAIS has not been reported. This study aimed to measure and compare fatigue progression within the shoulder girdle musculature of patients and healthy controls. 75 participants including 39 patients (20 females; 19 males) and 36 healthy controls (15 females; 21 males) participated in the study. Study evaluated the progression of muscle fatigue in 15 shoulder girdle muscles by means of surface and fine-wire EMG during submaximal contraction of four distinct movements (abduction, flexion, internal and external rotation). Shoulder strength, subjective pain experience (McGill Pain Questionnaire), and psychological status (Hospital Anxiety and Depression Scale) were also assessed. The results were compared between patient and control groups according to the gender. Despite marked fatigue observed in the majority of muscles particularly during flexion and abduction at 90°, overall results indicated a lower tendency of fatigue progression in the impingement group across the tests (p < 0.05 - p < 0.001). Shoulder Strength, pain experience, and psychological status were significantly different between the two groups (P < .05). Lower tendency to fatigue progression in the impingement group can be attributed to the presence of fear avoidance and pain-related muscle inhibition, which in turn lead to adaptations in motor programme to reduce muscle recruitment and activation. The significantly higher levels of pain experience and anxiety/depression in the impingement group further support this proposition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distraction-free ankle arthroscopy for anterolateral impingement.

PubMed

Rouvillain, Jean Louis; Daoud, Wael; Donica, Adrian; Garron, Emmanuel; Uzel, André Pierre

2014-08-01

The origin of chronic pain after external ankle sprain is better known with arthroscopy's contribution. Chronic hypertrophic synovitis of the anterolateral ankle region is seemingly the cause, resulting in "anterolateral ankle impingement." But is partial synovectomy with fibrosis resection under arthroscopy always possible without any distraction? Are results affected? This retrospective study concerned only patients with soft tissue ankle impingement. All cases with bone and joint diseases were excluded. The final sample of 24 patients had a mean age of 35 years (21-54 years) and presented anterolateral mechanical pain associated with oedema following external ankle sprain. Medical and rehabilitative treatment was undertaken for more than 6 months before arthroscopy. Average time between trauma and arthroscopy was 21 months (5-60 months). Clinical examination revealed no ankle instability or laxity. Debridement with joint lavage was systematically performed under arthroscopy without any distraction. Average patient follow-up was 22 months (12-92 months). All patients had a good Kitaoka score, with 22 patients registering excellent results. There were no septic complications or algodystrophy. Two transient hypoesthesias were observed in the dorsal surface and lateral border of the foot with full postoperative recovery at 6 months. Distraction was never used and simple dorsiflexion was sufficient to perform arthroscopic debridement. In this study, anterolateral ankle impingement diagnosis was primarily clinical. Arthroscopic treatment yielded significant benefits on pain, oedema and resumption of sport activities. Arthroscopic treatment of anterolateral ankle impingements is thus possible with simple dorsiflexion and no distraction, resulting in a possible decrease in complication rates. Level of evidence Retrospective cohort study, Level IV.

Impinging Jets and the Erodibility of Cohesive Sediment

NASA Astrophysics Data System (ADS)

Karamigolbaghi, M.; Bennett, S. J.; Ghaneeizad, S. M.; Atkinson, J. F.

2016-12-01

Defining the erodibility of cohesive sediment remains a critical challenge in Earth surface systems. The primary geomorphic law used in such applications relates erosion rate to an erodibility coefficient and an excess shear stress term. To assess erodibility, an inverse modeling approach can be adopted, wherein a known stress is applied to the cohesive sediment, and the erodibility parameters can be deduced through observation of erosion as a function of time. An impinging jet, as used in the jet erosion test, would appear to be an ideal flow (stress) source for erosion assessment. Recent work, however, has demonstrated that jet hydrodynamics can depart significantly from ideal flow conditions when employed for in situ erosion assessment. Here we will review jet theory and the use of jets for assessing the erodibility of cohesive sediment. Our results show that (1) flow confinement and the generation of secondary circulation can significantly change bed shear stress near and downstream of impingement, (2) the evolving scour hole shape, as conditioned by material characteristics and the erosion process, can significantly alter jet hydrodynamics and bed shear stress magnitudes and distributions near and downstream of impingement, and (3) incidental variations in material characteristics in carefully-executed, long-lived experiments can produce markedly different scour hole shapes and derived erodibility indices. Examples from experimental, numerical, and field observations will be used to illustrate these hydrodynamic and material effects on observed and predicted erosion rates. Because such effects are difficult to anticipate, the uncertainty of in situ cohesive sediment assessments using impinging jets can be quite large.

[Anterolateral ankle pain: differential diagnosis and approach. A case report].

PubMed

García-Renedo, R J; Pérez-Carro, L; Fernández-Torres, J J; Carranza-Bencano, A; Gómez-del Alamo, G

2011-01-01

The ankle soft tissue pathology represents a very painful disorder for patients who, often times, are not precisely diagnosed. Anterolateral ankle impingement is a condition that occurs in young people and athletes due to a plantar flexion-inversion mechanism. We report a case of anterolateral ankle impingement describing the arthroscopic technique and making the differential diagnosis considering other conditions.

30 CFR 14.21 - Laboratory-scale flame test apparatus.

Code of Federal Regulations, 2012 CFR

2012-07-01

... other and the flame from each jet impinges upon each other in pairs. The burner fuel must be at least 98... test chamber. (c) A U-shaped gas-fueled impinged jet burner ignition source, measuring 12 inches (30.5 cm) long and 4 inches (10.2 cm) wide, with two parallel rows of 6 jets each. Each jet is spaced...

30 CFR 14.21 - Laboratory-scale flame test apparatus.

Code of Federal Regulations, 2013 CFR

2013-07-01

... other and the flame from each jet impinges upon each other in pairs. The burner fuel must be at least 98... test chamber. (c) A U-shaped gas-fueled impinged jet burner ignition source, measuring 12 inches (30.5 cm) long and 4 inches (10.2 cm) wide, with two parallel rows of 6 jets each. Each jet is spaced...

30 CFR 14.21 - Laboratory-scale flame test apparatus.

Code of Federal Regulations, 2014 CFR

2014-07-01

... other and the flame from each jet impinges upon each other in pairs. The burner fuel must be at least 98... test chamber. (c) A U-shaped gas-fueled impinged jet burner ignition source, measuring 12 inches (30.5 cm) long and 4 inches (10.2 cm) wide, with two parallel rows of 6 jets each. Each jet is spaced...

Is there any value to arthroscopic debridement of ankle osteoarthritis and impingement?

PubMed

Phisitkul, Phinit; Tennant, Joshua N; Amendola, Annunziato

2013-09-01

This article summarizes the current literature regarding the use of arthroscopy for the various types of ankle osteoarthritis with impingement symptoms. Discussion includes the role of diagnostic arthroscopy and adjunctive use of arthroscopy with other modalities. The section on the authors' preferred technique describes our current operative and perioperative strategies in detail. Published by Elsevier Inc.

Numerical study of metal foam heat sinks under uniform impinging flow

NASA Astrophysics Data System (ADS)

Andreozzi, A.; Bianco, N.; Iasiello, M.; Naso, V.

2017-01-01

The ever-increasing demand for performance improvement and miniaturization of electronics has led to a significant generation of waste heat that must be dissipated to ensure a reliable device operation. The miniaturization of the components complicates this task. In fact, reducing the heat transfer area, at the same required heat rate, it is necessary to increase the heat flux, so that the materials operate in a temperature range suitable to its proper functioning. Traditional heat sinks are no longer capable of dissipating the generated heat and innovative approaches are needed to address the emerging thermal management challenges. Recently, heat transfer in open-cell metal foams under an impinging jet has received attention due to the considerable heat transfer potential of combining two cooling technologies: impinging jet and porous medium. This paper presents a numerical study on Finned Metal Foam (FMF) and Metal Foam (MF) heat sinks under impinging air jet cooling. The analysis is carried out by means of the commercial software COMSOL Multiphysics®. The purpose is to analyze the thermal performance of the metal foam heat sink, finned or not, varying its geometric parameters. Results are presented in terms of predicted dissipated heat rate, convective heat transfer coefficient and pressure losses.

Mobilization with movement and kinesiotaping compared with a supervised exercise program for painful shoulder: results of a clinical trial.

PubMed

Djordjevic, Olivera C; Vukicevic, Danijela; Katunac, Ljiljana; Jovic, Stevan

2012-07-01

The purpose of this study was to compare the efficacy of Mobilization with Movement (MWM) and kinesiotaping (KT) techniques with a supervised exercise program in participants with patients with shoulder pain. Twenty subjects with shoulder pain were included if subjects were diagnosed by the referring physician with either rotator cuff lesion with impingement syndrome or impingement shoulder syndrome. Participants were randomly assigned to 1 of 2 groups after clinical and radiologic assessment: group 1 was treated with MWM and KT techniques, whereas group 2 was treated with a supervised exercise program. The main outcome measures were active pain-free shoulder abduction and flexion tested on days 0, 5, and 10. Improvement in active pain-free shoulder range of motion was significantly higher in the group treated with MWM and KT. Repeated-measures analysis of variance indicated significant effects of treatment, time, and treatment×time interaction. This study suggests that MWM and KT may be an effective and useful treatment in range of motion augmentation of subjects with rotator cuff lesion and impingement syndrome or impingement shoulder syndrome. Copyright © 2012 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

Droplet-surface Impingement Dynamics for Intelligent Spray Design

NASA Technical Reports Server (NTRS)

VanderWal, Randy L.; Kizito, John P.; Tryggvason, Gretar; Berger, Gordon M.; Mozes, Steven D.

2004-01-01

Spray cooling has high potential in thermal management and life support systems by overcoming the deleterious effect of microgravity upon two-phase heat transfer. In particular spray cooling offers several advantages in heat flux removal that include the following: 1. By maintaining a wetted surface, spray droplets impinge upon a thin fluid film rather than a dry solid surface 2. Most heat transfer surfaces will not be smooth but rough. Roughness can enhance conductive cooling, aid liquid removal by flow channeling. 3. Spray momentum can be used to a) substitute for gravity delivering fluid to the surface, b) prevent local dryout and potential thermal runaway and c) facilitate liquid and vapor removal. Yet high momentum results in high We and Re numbers characterizing the individual spray droplets. Beyond an impingement threshold, droplets splash rather than spread. Heat flux declines and spray cooling efficiency can markedly decrease. Accordingly we are investigating droplet impingement upon a) dry solid surfaces, b) fluid films, c) rough surfaces and determining splashing thresholds and relationships for both dry surfaces and those covered by fluid films. We are presently developing engineering correlations delineating the boundary between splashing and non-splashing regions.

Eliminating impingement optimizes patellar biomechanics in high knee flexion.

PubMed

Tang, Qi-heng; Zhou, Yi-xin; Tang, Jing; Shao, Hong-yi; Wang, Guang-zhi

2010-08-01

We investigated the impact of eliminating the impingement between extensor mechanism and tibial insert on patellar tracking and patellar ligament tension in high knee flexion. Six cadaveric specimens were tested on an Oxford-type testing rig. The Genesis II knee system was implanted into each specimen knee with the traditional tibial insert and high-flex insert successively. Compared to traditional insert, the high-flex insert was characterized with a chambered anterior post and a chambered anterior lip which eliminates patella-post and patellar ligament-anterior lip impingements. The patella was tracked with an NDI Optotrak Certus system. The patellar ligament tension was measured using a NKB S-type tension transducer. There was a decrease of resultant patellar translation relative to the femur with statistically significant (P<0.05) at 90 degrees to 150 degrees of knee flexion and a decrease of patellar ligament tension with statistical significance (P<0.05) at 100 degrees, 120 degrees, 130 degrees, and 140 degrees of flexion using high-flex insert compared to traditional insert. Eliminating the impingement between extensor mechanism and implant in high knee flexion altered patellar tracking and reduced patellar ligament tension, which would facilitate high knee flexion.

Effect of Impingement Angle on landfalling Atmospheric River precipitation efficiency

NASA Astrophysics Data System (ADS)

Mehran, A.; Cao, Q.; Wang, K.; Cannon, F.; Ralph, M.; Lettenmaier, D. P.

2017-12-01

Atmospheric Rivers (ARs) along the western coast of North America in wintertime are associated with heavy winter precipitation and most flood events. ARs are narrow, elongated, synoptic jets of water vapor that transport moisture from the eastern Pacific to North Pacific coast of North America. Furthermore, the lowest levels of the atmosphere account for almost 75% of the water vapor transport through these rivers. The combination of high integrated water vapor in AR events and strong upslope winds results in heavy orographic precipitation in regions where the narrow AR jets make landfall. We analyzed 19 years (1997 2015) of landfalling ARs over a transect along the U.S. West Coast consisting of two river basins from coastal Washington and Northern California (Chehalis basin and the Russian River basin) to highlight the impingement angle impact on precipitation rainout efficiency. We have studied water vapor data from Climate Forecast System reanalysis (CFSR) on AR dates to calculate the impingement angle and associated total amount of water vapor. Rainout efficiency is defined and calculated as the ratio of total amount of water vapor that has precipitated over each basin. Our results show that extreme AR events which impingement angle is orthogonal to basin exposure, have greater rainout efficiency.

Arthroscopic Treatment of a Displaced Nonunion of the Anterior Inferior Iliac Spine Causing Extra-articular Impingement.

PubMed

Shibahara, Motoi; Ohnishi, Yasuo; Honda, Eisaburo; Matsuda, Dean K; Uchida, Soshi

2017-07-01

This report describes a case of nonunion of an anterior inferior iliac spine (AIIS) apophyseal avulsion fracture with resultant subspine impingement combined with symptomatic femoroacetabular impingement (FAI). A 16-year-old male soccer player presented with a 6-month history of right groin pain exacerbated by kicking and running. The patient was diagnosed with a displaced nonunion of the AIIS apophysis avulsion fracture causing secondary extra-articular impingement beyond cam-type FAI by physical examination and radiological findings. The authors performed arthroscopic AIIS decompression, with concurrent FAI correction and labral repair and capsular closure. At 4 months after surgery, a radiograph and a computed tomography scan showed complete bony union of the AIIS apophyseal nonunion. Modified Harris Hip Sore and Nonarthritic Hip Score improved from 74.8 and 61, respectively, to 100 for both at final follow-up. The effectiveness of arthroscopic decompression of the AIIS as part of a comprehensive minimally invasive surgery including FAI correction and labral repair resulted in complete union of the AIIS and pain-free return to sport and bony union. [Orthopedics. 2017; 40(4):e725-e728.]. Copyright 2017, SLACK Incorporated.

Evaluation of cooling performance of impinging jet array over various dimpled surfaces

NASA Astrophysics Data System (ADS)

Kim, Sun-Min; Kim, Kwang-Yong

2016-04-01

Various configurations of an impinging jet-dimple array cooling system were evaluated in terms of their heat transfer and pressure drop performances. The steady incompressible laminar flow and heat transfer in the cooling system were analyzed using three-dimensional Navier-Stokes equations. The obtained numerical results were validated by a comparison with experimental data for the local Nusselt number distribution. The area-averaged Nusselt number on the projected area and the pressure drop through the system were selected as the performance parameters. Among the four tested configurations—inline concave, staggered concave, inline convex, and staggered convex—the staggered convex impinging jet-dimple array showed the best heat transfer performance whereas the staggered-concave configuration showed the lowest pressure drop. A parametric study with two geometric variables, i.e., the height of dimple and the diameter of dimple, was also conducted for the staggered-convex impinging jet-dimple array. As a result, the best heat transfer and pressure drop performances were achieved when the ratio of the height of dimple to the diameter of jet was 0.8. And, the increase in the ratio of the diameter of dimple to the diameter of jet yielded monotonous increase in the heat transfer performance.

Rotational effects on impingement cooling

NASA Technical Reports Server (NTRS)

Epstein, A. H.; Kerrebrock, J. L.; Koo, J. J.; Preiser, U. Z.

1987-01-01

The present consideration of rotation effects on heat transfer in a radially exhausted, impingement-cooled turbine blade model gives attention to experimental results for Reynolds and Rossby numbers and blade/coolant temperature ratio values that are representative of small gas turbine engines. On the basis of a model that encompasses the effects of Coriolis force and buoyancy on heat transfer, bouyancy is identified as the cause of an average Nusselt number that is 20-30 percent lower than expected from previous nonrotating data. A heuristic model is proposed which predicts that the impingement jets nearest the blade roots should deflect inward, due to a centripetal force generated by their tangential velocity counter to the blade motion. Potentially serious thermal stresses must be anticipated from rotation effects in the course of blade design.

Solid impingement erosion mechanisms and characterization of erosion resistance of ductile metals

NASA Technical Reports Server (NTRS)

Rao, V. P.; Buckley, D. H.

1982-01-01

Experimental results pertaining to spherical glass bead and angular crushed glass particle impingement are presented. A concept of energy adsorption to explain the failure of material is proposed. The erosion characteristics of several pure metals were correlated with the proposed energy parameters and with other properties. Correlations of erosion and material properties were also carried out with these materials to study the effect of the angle of impingement. Analyses of extensive erosion data indicate that surface energy, strain energy, melting point, bulk modulus, hardness, ultimate resilience, atomic volume and product of linear coefficient of thermal expansion, bulk modulus, and temperature rise required for melting, and ultimate resilience, and hardness exhibit the best correlations. It appears that both energy and thermal properties contribute to the total erosion.

Progress in NEXT Ion Optics Modeling

NASA Technical Reports Server (NTRS)

Emhoff, Jerold W.; Boyd, Iain D.

2004-01-01

Results are presented from an ion optics simulation code applied to the NEXT ion thruster geometry. The error in the potential field solver of the code is characterized, and methods and requirements for reducing this error are given. Results from a study on electron backstreaming using the improved field solver are given and shown to compare much better to experimental results than previous studies. Results are also presented on a study of the beamlet behavior in the outer radial apertures of the NEXT thruster. The low beamlet currents in this region allow over-focusing of the beam, causing direct impingement of ions on the accelerator grid aperture wall. Different possibilities for reducing this direct impingement are analyzed, with the conclusion that, of the methods studied, decreasing the screen grid aperture diameter eliminates direct impingement most effectively.

Airfoil for a gas turbine

DOEpatents

Liang, George [Palm City, FL

2011-01-18

An airfoil is provided for a gas turbine comprising an outer structure comprising a first wall, an inner structure comprising a second wall spaced relative to the first wall such that a cooling gap is defined between at least portions of the first and second walls, and seal structure provided within the cooling gap between the first and second walls for separating the cooling gap into first and second cooling fluid impingement gaps. An inner surface of the second wall may define an inner cavity. The inner structure may further comprise a separating member for separating the inner cavity of the inner structure into a cooling fluid supply cavity and a cooling fluid collector cavity. The second wall may comprise at least one first impingement passage, at least one second impingement passage, and at least one bleed passage.

Sensitivity analysis for the control of supersonic impinging jet noise

NASA Astrophysics Data System (ADS)

Nichols, Joseph W.; Hildebrand, Nathaniel

2016-11-01

The dynamics of a supersonic jet that impinges perpendicularly on a flat plate depend on complex interactions between fluid turbulence, shock waves, and acoustics. Strongly organized oscillations emerge, however, and they induce loud, often damaging, tones. We investigate this phenomenon using unstructured, high-fidelity Large Eddy Simulation (LES) and global stability analysis. Our flow configurations precisely match laboratory experiments with nozzle-to-wall distances of 4 and 4.5 jet diameters. We use multi-block shift-and-invert Arnoldi iteration to extract both direct and adjoint global modes that extend upstream into the nozzle. The frequency of the most unstable global mode agrees well with that of the emergent oscillations in the LES. We compute the "wavemaker" associated with this mode by multiplying it by its corresponding adjoint mode. The wavemaker shows that this instability is most sensitive to changes in the base flow slightly downstream of the nozzle exit. By modifying the base flow in this region, we then demonstrate that the flow can indeed be stabilized. This explains the success of microjets as an effective noise control measure when they are positioned around the nozzle lip. Computational resources were provided by the Argonne Leadership Computing Facility.

Acetabular labral tears in patients with sports injury.

PubMed

Kang, Chan; Hwang, Deuk-Soo; Cha, Soo-Min

2009-12-01

We wanted to investigate acetabular labral tears and their correlation with femoroacetabular impingement in patients with sports injury. Among 111 patients who were diagnosed with the acetabular labral tears after arthroscopic treatment from January 2004 to December 2007, we selected 41 patients with sports injury. There were 12 cases of Taekwondo injury, 5 of golf injury, 4 of soccer injury, 3 of gymnastics injury, 2 of Hapkido injury, 2 of aerobics injury, 2 of rock-climbing injury, 2 of fitness training injury and 9 of other sports injuries. We checked the subtypes of acetabular labral tears and the accompanying femoroacetabular impingement. For the cases with accompanying femoroacetabular impingement, we investigated the subtypes according to the types of sports, gender and age. At last follow-up, we checked the Harris Hip Score (HHS), the Hip Outcome Score (HOS) sports scale and the percentage of patients who returned to their sports activity. The average age of symptomatic onset was 26 years (range, 12 to 65 years). The ratio of males to females was 29 : 12. An average duration of the hip pain was 17 months (range, 1 to 60 months). The degenerative type of acetabular labral tears was the most prevalent with 32 cases (78%), and there were 9 cases (22%) of the partial tear type. Thirty cases (73%) were accompanied by femoroacetabular impingement. The average age of the 23 cases (56%) of the cam-type was 23 years (range, 12 to 48 years), and it was more likely to occur in men (87%) and for people practicing martial arts such as Taekwondo or Hapkido. An average age of the 5 cases (12%) of the pincer-type was 26 (range, 16 to 43 years), it usually occurred in women (60%) and for non-martial arts such as golf and gymnastics. There were 2 cases of the mixed type (cam + pincer-type). At 27 months follow-up, the HHS was 61 to 92 points, the HOS sports scale increased 43 to 75%, and the rate of returning to sports was 71%. In spite of the early expression of symptoms and the short duration of the acetabular labral tears, the high rate of degenerative acetabular labral tears in sports patients is likely associated with repetitive injury after the expression of symptoms. Femoroacetabular impingement in sports patients is seemed to be a cause of the early occurrence of acetabular labral tears. Because the possibility of acetabular labral tears is high in femoroacetabular impingement, sports patients may need to undergo early screening for the diagnosis and care of femoroacetabular impingement.

Synthesis of superhydrophobic alumina membrane: Effects of sol-gel coating, steam impingement and water treatment

NASA Astrophysics Data System (ADS)

Ahmad, N. A.; Leo, C. P.; Ahmad, A. L.

2013-11-01

Ceramic membranes possess natural hydrophilicity thus tending to absorb water droplets. The absorption of water molecules on membrane surface reduces their application in filtration, membrane distillation, osmotic evaporation and membrane gas absorption. Fluoroalkylsilane (FAS) grafting allows the conversion of hydrophilic ceramic membranes into superhydrophobic thin layer, but it usually introduces a great increment of mass transfer resistance. In this study, superhydrophobic alumina membranes were synthesized by dip coating alumina support into sol-gel and grafted with the fluoroalkylsilane (FAS) named (heptadecafluoro-1,1,2,2-tetra hydrodecyl) triethoxysilane. Steam impingement and water treatment acted as additional steps to generate surface roughness on sol-gel and most importantly to reduce mass transfer resistance. Superhydrophobic alumina membrane with high water contact angle (158.4°) and low resistance (139.5 ± 24.9 G m-1) was successfully formed when the alumina membrane was dip coated into sol-gel for 7 s, treated with steam impingement for 1 min and immersed in hot water at 100 °C. However, the mass transfer resistance was greatly induced to 535.6 ± 23.5 G m-1 when the dip coating time was increased to 60 s. Long dip coating time contributes more on the blockage of porous structure rather than creates a thin film on the top of membrane surface. Reducing the pore size and porosity significantly due to increase of coating molecules deposited on the membrane. Steam impingement for 1 min promoted the formation of cones and valleys on the sol-gel, but the macro-roughness was destroyed when the steam impingement duration was extended to more than 3 min. The immersions of membranes into hot water at temperatures higher than 60 °C encouraged the formation of boehmite which enhances the formation of additional roughness and enlarges pore size greatly. Thus, this work showed that the formation of superhydrophobic alumina membrane with low resistance is influenced by three factors; sol-gel dip coating time, steam impingement time and temperature of water treatment. The optimum dip coating time could promote appropriate thickness of the sol-gel layer on the membrane support. The highest surface roughness and porosity could be created when the sol-gel layer was further treated with optimum steam impingement duration and immersed in hot water at 100 °C. The presence of appropriate sol-gel thickness can reduce the penetration of FAS during the grafting and reduce the membrane resistance.

Effect of Bearing Defects

DTIC Science & Technology

1974-12-01

defect types were tested at various levels: Comet- Tail, Dig-Nick, Dirt Brinell, Grind-Skip Lines, Impingement, Orange Peel , Pit, Scratch and "Liney...Shallow irregular indentation of surface. <.0015 max. dim. -(<.0008)*’ Otange Peel Pebbly appearance of raceway surface. Small ** Comet Tail Pit...scratch; dig-nick; impingement; grind-skip lines; and orange peel . The data obtained indicated that these defects in most cases, affected bearing

Jet-impingement heat transfer in gas turbine systems.

PubMed

Han, B; Goldstein, R J

2001-05-01

A review of jet-impingement heat transfer in gas turbine systems is presented. Characteristics of the different flow regions for submerged jets--free jet, stagnation flow, and wall jet--are reviewed. Heat transfer characteristics of both single and multiple jets are discussed with consideration of the effects of important parameters relevant to gas turbine systems including curvature of surfaces, crossflow, angle of impact, and rotation.

Cooling air recycling for gas turbine transition duct end frame and related method

DOEpatents

Cromer, Robert Harold; Bechtel, William Theodore; Sutcu, Maz

2002-01-01

A method of cooling a transition duct end frame in a gas turbine includes the steps of a) directing cooling air into the end frame from a region external of the transition duct and the impingement cooling sleeve; and b) redirecting the cooling air from the end frame into the annulus between the transition duct and the impingement cooling sleeve.

Diffractive-refractive optics: X-ray splitter.

PubMed

Hrdý, Jaromír

2010-01-01

The possibility of splitting a thin (e.g. undulator) X-ray beam based on diffraction-refraction effects is discussed. The beam is diffracted from a crystal whose diffracting surface has the shape of a roof with the ridge lying in the plane of diffraction. The crystal is cut asymmetrically. One half of the beam impinges on the left-hand part of the roof and the other half impinges on the right-hand side of the roof. Owing to refraction the left part of the beam is deviated to the left whereas the right part is deviated to the right. The device proposed consists of two channel-cut crystals with roof-like diffraction surfaces; the crystals are set in a dispersive position. The separation of the beams after splitting is calculated at a distance of 10 m from the crystals for various asymmetry and inclination angles. It is shown that such a splitting may be utilized for long beamlines. Advantages and disadvantages of this method are discussed.

Community, environmental, and occupational health risks associated with fossil fuel energy production

NASA Astrophysics Data System (ADS)

Shepherd, Mark A.

Short-term and long-term health risks associated with fossil fuel power production can be grouped into three broad categories: risks to the surrounding community, the natural environment and to plant workers. The results of three studies examining the primary short-term or long-term impacts of fossil fuel power plants are presented within this dissertation. The first study estimates the plausible community health effects associated with peak SO2 emissions from three coal-fired power plants in the Baltimore, Maryland area. Concentrations from mobile and stationary air monitoring were compared to human clinical studies that demonstrated respiratory morbidity. Results indicate that exposure concentrations are below levels associated with respiratory symptoms. A single measurement at one monitoring site, however, may indicate risk of asymptomatic lung function decrement for SO2-sensitive asthmatics. The second study estimates the relationship between operational, environmental and temporal factors at a Texas coastal power plant and fish and shellfish impingement. Impingement is a long-term risk to fish populations near power plants. When large quantities of water are withdrawn from water bodies for cooling, fish and shellfish may be harmed if impinged against screens intended to remove debris. In this study, impingement of fish and shellfish was best explained by dissolved oxygen concentration, sampling month and sampling time. When examined separately, temperature and sampling month were most important in explaining fish impingement, while for shellfish, sampling month and sampling time were most important. Operational factors were not significant predictors of impingement. The third study examines whether the number of worker similar exposure groups classified using observation methods was the same as groups classified using personal exposure monitoring. Using observational techniques and personal monitoring, power plant workers were grouped according to exposure similarity for respirable silica, respirable particulates, total dust, chromium and arsenic. For respirable particulates, the number of groups estimated using observational techniques is similar to the number estimated using personal monitoring. For respirable silica, total dust, and arsenic, observational techniques indicated more groups than indicated using personal monitoring. No significant exposure differences to chromium were found. Except for respirable silica, the number of similarly exposed groups among power plants is comparable.

A numerical study on high-pressure water-spray cleaning for CSP reflectors

NASA Astrophysics Data System (ADS)

Anglani, Francesco; Barry, John; Dekkers, Willem

2016-05-01

Mirror cleaning for concentrated solar thermal (CST) systems is an important aspect of operation and maintenance (O&M), which affects solar field efficiency. The cleaning process involves soil removal by erosion, resulting from droplet impingement on the surface. Several studies have been conducted on dust accumulation and CSP plant reflectivity restoration, demonstrating that parameters such as nozzle diameter, jet impingement angle, interaxial distance between nozzles, standoff distance, water velocity, nozzle pressure and others factors influence the extent of reflectance restoration. In this paper we aim at identifying optimized cleaning strategies suitable for CST plants, able to restore mirror reflectance by high-pressure water-spray systems through the enhancement of shear stress over reflectors' surface. In order to evaluate the forces generated by water-spray jet impingement during the cleaning process, fluid dynamics simulations have been undertaken with ANSYS CFX software. In this analysis, shear forces represent the "critical phenomena" within the soil removal process. Enhancing shear forces on a particular area of the target surface, varying the angle of impingement in combination with the variation of standoff distances, and managing the interaxial distance of nozzles can increase cleaning efficiency. This procedure intends to improve the cleaning operation for CST mirrors reducing spotted surface and increasing particles removal efficiency. However, turbulence developed by adjacent flows decrease the shear stress generated on the reflectors surface. The presence of turbulence is identified by the formation of "fountain regions" which are mostly responsible of cleaning inefficiency. By numerical analysis using ANSYS CFX, we have modelled a stationary water-spray system with an array of three nozzles in line, with two angles of impingement: θ = 90° and θ = 75°. Several numerical tests have been carried out, varying the interaxial distance of nozzles, standoff distance, jet pressure and jet impingement angle in order to identify effective and efficient cleaning procedures to restore collectors' reflectance, decrease turbulence and improve CST plant efficiency. Results show that the forces generated over the flat target surface are proportional to the inlet pressure and to the water velocity over the surface, and that the shear stresses decrease as the standoff distance increases.

Impact of movement training on upper limb motor strategies in persons with shoulder impingement syndrome

PubMed Central

Roy, Jean-Sébastien; Moffet, Hélène; McFadyen, Bradford J; Lirette, Richard

2009-01-01

Background Movement deficits, such as changes in the magnitude of scapulohumeral and scapulathoracic muscle activations or perturbations in the kinematics of the glenohumeral, sternoclavicular and scapulothoracic joints, have been observed in people with shoulder impingement syndrome. Movement training has been suggested as a mean to contribute to the improvement of the motor performance in persons with musculoskeletal impairments. However, the impact of movement training on the movement deficits of persons with shoulder impingement syndrome is still unknown. The aim of this study was to evaluate the short-term effects of supervised movement training with feedback on the motor strategies of persons with shoulder impingement syndrome. Methods Thirty-three subjects with shoulder impingement were recruited. They were involved in two visits, one day apart. During the first visit, supervised movement training with feedback was performed. The upper limb motor strategies were evaluated before, during, immediately after and 24 hours after movement training. They were characterized during reaching movements in the frontal plane by EMG activity of seven shoulder muscles and total excursion and final position of the wrist, elbow, shoulder, clavicle and trunk. Movement training consisted of reaching movements performed under the supervision of a physiotherapist who gave feedback aimed at restoring shoulder movements. One-way repeated measures ANOVAs were run to analyze the effect of movement training. Results During, immediately after and 24 hours after movement training with feedback, the EMG activity was significantly decreased compared to the baseline level. For the kinematics, total joint excursion of the trunk and final joint position of the trunk, shoulder and clavicle were significantly improved during and immediately after training compared to baseline. Twenty-four hours after supervised movement training, the kinematics of trunk, shoulder and clavicle were back to the baseline level. Conclusion Movement training with feedback brought changes in motor strategies and improved temporarily some aspects of the kinematics. However, one training session was not enough to bring permanent improvement in the kinematic patterns. These results demonstrate the potential of movement training in the rehabilitation of movement deficits associated with shoulder impingement syndrome. PMID:19445724

Anterolateral ankle impingement in adolescents: outcomes of nonoperative and operative treatment.

PubMed

Edmonds, Eric W; Chambers, Reid; Kaufman, Elizabeth; Chambers, Henry G

2010-03-01

Ankle sprains in adolescents usually resolve with conservative management but a few patients may develop ankle impingement syndrome. There have been adult studies addressing surgical treatment of this pathology, but our study evaluated the surgical management of anterolateral ankle impingement in adolescents by comparing their outcomes after nonoperative treatment and subsequent surgical intervention. Thirteen patients (children and adolescents) diagnosed with ankle impingement by history, physical examination, and magnetic resonance imaging during a 9-year period at our institution underwent eventual arthroscopic debridement. A retrospective chart review of these patients was performed and they were evaluated using the American Orthopedic Foot and Ankle Society (AOFAS) functional rating scale on 3 separate occasions: (1) initial presentation, (2) termination of nonoperative management, and (3) final postoperative follow-up visit. Thirteen adolescents (11 girls and 2 boys; 14 ankles) with a mean age of 15.6 (11.9-18.3) years met the inclusion criteria; of these, all had arthroscopic surgery. Mean duration of reported symptoms was 9.6 (4-15) months and mean duration of nonoperative management (physical therapy, activity modifications) was 6.9 (2-12) months. The mean AOFAS rating (out of 100 total) at initial presentation was 68.4 (40-84) and after nonoperative management was no better with a mean of 68.2 (63-76). The mean AOFAS rating at final follow-up was 90.6 (52-100), which was statistically significant (P

Ischiofemoral impingement and hamstring dysfunction as a potential pain generator after ischial tuberosity apophyseal fracture non-union/malunion.

PubMed

Spencer-Gardner, Luke; Bedi, Asheesh; Stuart, Michael J; Larson, Christopher M; Kelly, Bryan T; Krych, Aaron J

2017-01-01

The purpose of this study was to describe the occurrence of ischiofemoral impingement (IFI) and hamstring dysfunction following malunion or non-union of ischial tuberosity apophyseal avulsion fractures and report the short-term outcomes of surgical treatment with regard to alleviating symptomatic extra-articular impingement. All patients who underwent surgery for recalcitrant hip and buttock pain in the setting of prior ischial tuberosity avulsion fracture at three tertiary-level hip preservation centres were included for this review. A total of ten patients met our inclusion criteria and underwent sciatic neurolysis, resection of the ischial tuberosity fragment and hamstring reattachment. Clinical outcomes scores were collected post-operatively including the Modified Harris Hip Score (mHHS) and the Hip Outcomes Score (HOS). Ten patients with a mean age of 18 years (range 14-28) underwent surgery for symptomatic ischiofemoral impingement after ischial tuberosity avulsion fracture. At a mean of 2.2-year follow-up (range 1.7-3.5), the median post-operative mHHS was 89.7 (65.7-96.8) and HOS ADL and Sport subscales were 90 % or greater in all cases. Five patients (50 %) rated their hip as normal, and five patients (50 %) rated their hip as near normal. Malunion or non-union following ischial tuberosity apophyseal fracture can lead to IFI and hamstring dysfunction. Clinically, the resultant pain and dysfunction is often chronic, and can be debilitating. In select cases, a reliable surgical technique is presented to improve hamstring function and correct ischiofemoral impingement in this setting with good-to-excellent outcomes in the majority of cases at short-term follow-up. IV.

An Experimental and Numerical Study of Diesel Spray Impingement on a Flat Plate

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

Zhao, Le; Torelli, Roberto; Zhu, Xiucheng

Combustion systems with advanced injection strategies have been extensively studied, but there still exists a significant fundamental knowledge gap on fuel spray interactions with the piston surface and chamber walls. This paper is meant to provide detailed data on spray-wall impingement physics and support the spray-wall model development. The experimental work of spray-wall impingement with non-vaporizing spray characterization, was carried out in a high pressure-temperature constant-volume combustion vessel. The simultaneous Mie scattering of liquid spray and schlieren of liquid and vapor spray were carried out. Diesel fuel was injected at a pressure of 1500 bar into ambient gas at amore » density of 22.8 kg/m3 with isothermal conditions (fuel, ambient, and plate temperatures of 423 K). A Lagrangian-Eulerian modeling approach was employed to characterize the spray-gas and spray-wall interactions in the CONVERGE framework by means of a Reynolds-Averaged Navier-Stokes (RANS) formulation. A set of turbulence and spray break-up model constants was identified to properly match the aforementioned measurements of liquid penetration within their experimental confidence intervals. An accuracy study on varying the minimum mesh size was also performed to ensure the grid convergence of the numerical results. Experimentally validated computational fluid dynamics (CFD) simulations were then used to investigate the local spray characteristics in the vicinity of the wall with a particular focus on Sauter Mean Diameter (SMD) and Reynolds and Weber numbers. The analysis was performed by considering before- and after-impingement conditions in order to take in account the influence of the impinged wall on the spray morphology.« less

Posterior ankle impingement syndrome in football players: Case series of 26 elite athletes.

PubMed

Kudaş, Savaş; Dönmez, Gürhan; Işık, Çetin; Çelebi, Mesut; Çay, Nurdan; Bozkurt, Murat

2016-12-01

To describe a clinical treatment algorithm for posterior ankle impingement (PAI) syndrome in professional football players. A case series of 26 elite professional football players diagnosed and treated for posterior ankle impingement syndrome were included for the study. All of the athletes received conservative treatment with physical therapy modalities initially. If the first line medical treatment and rehabilitation was ineffective to alleviate the symptoms, ultrasound-guided corticosteroid injection was proposed and thereafter the patients underwent posterior ankle arthroscopy if the complaints are still unresolved. The pain scores (AOFAS, VAS), and time to return to play were the main outcome measures. The complaints of 18 (69.2%) players were subsided with non-surgical treatment whereas three of acute cases and five of the chronic cases did not respond to medical treatment and arthroscopic surgery was performed for eight athletes. Eighteen players returned to training for a mean time of 36.3 days (24-42 days) after conservative treatment. The patients who underwent arthroscopic surgery returned to training for a mean time of 49.8 days (42-56 days) after the surgery. All athletes returned to their previous level of competition after treatment without any complications or recurrence in a mean follow-up 36.5 months (19-77 months). Non-surgical treatment modalities were effective in 2/3 of posterior ankle impingement syndrome in elite football players. On the other hand, posterior ankle arthroscopy is safe and effective treatment option for posterior ankle impingement syndrome if the conservative treatment fails. Level IV, Therapeutic study. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

Effects of the humeral tray component positioning for onlay reverse shoulder arthroplasty design: a biomechanical analysis.

PubMed

Berhouet, Julien; Kontaxis, Andreas; Gulotta, Lawrence V; Craig, Edward; Warren, Russel; Dines, Joshua; Dines, David

2015-04-01

Recent shoulder prostheses have introduced a concept of a universal humeral stem component platform that has an onlay humeral tray for the reverse total shoulder arthroplasty (RTSA). No studies have reported how humeral tray positioning can affect the biomechanics of RTSA. The Newcastle Shoulder Model was used to investigate the biomechanical effect of humeral tray positioning in the Biomet Comprehensive Total Shoulder System (Biomet, Warsaw, IN, USA) RTSA. Five humeral tray configuration positions were tested: no offset, and 5 mm offset in the anterior, posterior, medial, and lateral positions. Superior and inferior impingement were evaluated for abduction, scapular plane elevation, forward flexion, and external/internal rotation with the elbow at the side (adduction) and at 90° of shoulder abduction. Muscle lengths and moment arms (elevating and rotational) were calculated for the deltoid, the infraspinatus, the teres minor, and the subscapularis. Inferior impingement was not affected by the humeral tray position. There was less superior impingement during abduction, scapular plane elevation, and rotation with the shoulder when the tray was placed laterally or posteriorly. The subscapularis rotational moment arm was increased with a posterior offset, whereas infraspinatus and teres minor rotational moment arms were increased with an anterior offset. Very little change was observed for the deltoid elevating moment arm or for its muscle length. Positioning the humeral tray with posterior offset offers a biomechanical advantage for patients needing RTSA by decreasing superior impingement and increasing the internal rotational moment arm of the subscapularis, without creating inferior impingement. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

The recognition and evaluation of patterns of compensatory injury in patients with mechanical hip pain.

PubMed

Hammoud, Sommer; Bedi, Asheesh; Voos, James E; Mauro, Craig S; Kelly, Bryan T

2014-03-01

In active individuals with femoroacetabular impingement (FAI), the resultant reduction in functional range of motion leads to high impaction loads at terminal ranges. These increased forces result in compensatory effects on bony and soft tissue structures within the hip joint and hemipelvis. An algorithm is useful in evaluating athletes with pre-arthritic, mechanical hip pain and associated compensatory disorders. A literature search was performed by a review of PubMed articles published from 1976 to 2013. Level 4. Increased stresses across the bony hemipelvis result when athletes with FAI attempt to achieve supraphysiologic, terminal ranges of motion (ROM) through the hip joint required for athletic competition. This can manifest as pain within the pubic joint (osteitis pubis), sacroiliac joint, and lumbosacral spine. Subclinical posterior hip instability may result when attempts to increase hip flexion and internal rotation are not compensated for by increased motion through the hemipelvis. Prominence of the anterior inferior iliac spine (AIIS) at the level of the acetabular rim can result in impingement of the anterior hip joint capsule or iliocapsularis muscle origin against the femoral head-neck junction, resulting in a distinct form of mechanical hip impingement (AIIS subspine impingement). Iliopsoas impingement (IPI) has also been described as an etiology for anterior hip pain. IPI results in a typical 3-o'clock labral tear as well as an inflamed capsule in close proximity to the overlying iliopsoas tendon. Injury in athletic pubalgia occurs during high-energy twisting activities in which abnormal hip ROM and resultant pelvic motion lead to shearing across the pubic symphysis. Failure to recognize and address concomitant compensatory injury patterns associated with intra-articular hip pathology can result in significant disability and persistent symptoms in athletes with pre-arthritic, mechanical hip pain. B.

Qualitative Analysis of E-Liquid Emissions as a Function of Flavor Additives Using Two Aerosol Capture Methods.

PubMed

Eddingsaas, Nathan; Pagano, Todd; Cummings, Cody; Rahman, Irfan; Robinson, Risa; Hensel, Edward

2018-02-13

This work investigates emissions sampling methods employed for qualitative identification of compounds in e-liquids and their resultant aerosols to assess what capture methods may be sufficient to identify harmful and potentially harmful constituents present. Three popular e-liquid flavors (cinnamon, mango, vanilla) were analyzed using qualitative gas chromatography-mass spectrometry (GC-MS) in the un-puffed state. Each liquid was also machine-puffed under realistic-use flow rate conditions and emissions were captured using two techniques: filter pads and methanol impingers. GC-MS analysis was conducted on the emissions captured using both techniques from all three e-liquids. The e-liquid GC-MS analysis resulted in positive identification of 13 compounds from the cinnamon flavor e-liquid, 31 from mango, and 19 from vanilla, including a number of compounds observed in all e-liquid experiments. Nineteen compounds were observed in emissions which were not present in the un-puffed e-liquid. Qualitative GC-MS analysis of the emissions samples identify compounds observed in all three samples: e-liquid, impinge, and filter pads, and each subset thereof. A limited number of compounds were observed in emissions captured with impingers, but were not observed in emissions captured using filter pads; a larger number of compounds were observed on emissions collected from the filter pads, but not those captured with impingers. It is demonstrated that sampling methods have different sampling efficiencies and some compounds might be missed using only one method. It is recommended to investigate filter pads, impingers, thermal desorption tubes, and solvent extraction resins to establish robust sampling methods for emissions testing of e-cigarette emissions.

Qualitative Analysis of E-Liquid Emissions as a Function of Flavor Additives Using Two Aerosol Capture Methods

PubMed Central

Eddingsaas, Nathan; Pagano, Todd; Cummings, Cody; Rahman, Irfan; Robinson, Risa

2018-01-01

This work investigates emissions sampling methods employed for qualitative identification of compounds in e-liquids and their resultant aerosols to assess what capture methods may be sufficient to identify harmful and potentially harmful constituents present. Three popular e-liquid flavors (cinnamon, mango, vanilla) were analyzed using qualitative gas chromatography-mass spectrometry (GC-MS) in the un-puffed state. Each liquid was also machine-puffed under realistic-use flow rate conditions and emissions were captured using two techniques: filter pads and methanol impingers. GC-MS analysis was conducted on the emissions captured using both techniques from all three e-liquids. The e-liquid GC-MS analysis resulted in positive identification of 13 compounds from the cinnamon flavor e-liquid, 31 from mango, and 19 from vanilla, including a number of compounds observed in all e-liquid experiments. Nineteen compounds were observed in emissions which were not present in the un-puffed e-liquid. Qualitative GC-MS analysis of the emissions samples identify compounds observed in all three samples: e-liquid, impinge, and filter pads, and each subset thereof. A limited number of compounds were observed in emissions captured with impingers, but were not observed in emissions captured using filter pads; a larger number of compounds were observed on emissions collected from the filter pads, but not those captured with impingers. It is demonstrated that sampling methods have different sampling efficiencies and some compounds might be missed using only one method. It is recommended to investigate filter pads, impingers, thermal desorption tubes, and solvent extraction resins to establish robust sampling methods for emissions testing of e-cigarette emissions. PMID:29438289

Reduction of glycine particle size by impinging jet crystallization.

PubMed

Tari, Tímea; Fekete, Zoltán; Szabó-Révész, Piroska; Aigner, Zoltán

2015-01-15

The parameters of crystallization processes determine the habit and particle size distribution of the products. A narrow particle size distribution and a small average particle size are crucial for the bioavailability of poorly water-soluble pharmacons. Thus, particle size reduction is often required during crystallization processes. Impinging jet crystallization is a method that results in a product with a reduced particle size due to the homogeneous and high degree of supersaturation at the impingement point. In this work, the applicability of the impinging jet technique as a new approach in crystallization was investigated for the antisolvent crystallization of glycine. A factorial design was applied to choose the relevant crystallization factors. The results were analysed by means of a statistical program. The particle size distribution of the crystallized products was investigated with a laser diffraction particle size analyser. The roundness and morphology were determined with the use of a light microscopic image analysis system and a scanning electron microscope. Polymorphism was characterized by differential scanning calorimetry and powder X-ray diffraction. Headspace gas chromatography was utilized to determine the residual solvent content. Impinging jet crystallization proved to reduce the particle size of glycine. The particle size distribution was appropriate, and the average particle size was an order of magnitude smaller (d(0.5)=8-35 μm) than that achieved with conventional crystallization (d(0.5)=82-680 μm). The polymorphic forms of the products were influenced by the solvent ratio. The quantity of residual solvent in the crystallized products was in compliance with the requirements of the International Conference on Harmonization. Copyright © 2014 Elsevier B.V. All rights reserved.

On numerical heat transfer characteristic study of flat surface subjected to variation in geometric thickness

NASA Astrophysics Data System (ADS)

Umair, Siddique Mohammed; Kolawale, Abhijeet Rangnath; Bhise, Ganesh Anurath; Gulhane, Nitin Parashram

Thermal management in the looming world of electronic packaging system is the most prior and conspicuous issue as far as the working efficiency of the system is concerned. The cooling in such systems can be achieved by impinging air jet over the heat sink as jet impingement cooling is one of the cooling technologies which are widely studied now. Here the modulation in impinging and geometric parameters results in the establishment of the characteristic cooling rate over the target surface. The characteristic cooling curve actually resembles non-uniformity in cooling rate. This non-uniformity favors the area average heat dissipation rate. In order to study the non-uniformity in cooling characteristic, the present study takes an initiative in plotting the local Nusselt number magnitude against the non-dimensional radial distance of the different thickness of target surfaces. For this, the steady temperature distribution over the target surface under the impingement of air jet is being determined numerically. The work is completely inclined towards the determination of critical value of geometric thickness below which the non-uniformity in the Nusselt profile starts. This is done by numerically examining different target surfaces under constant Reynolds number and nozzle-target spacing. The occurrences of non-uniformity in Nusselt profile contributes to over a 42% enhancement in area average Nusselt magnitude. The critical value of characteristic thickness (t/d) reported in the present investigation approximate to 0.05. Below this value, the impingement of air jet generates a discrete pressure zones over the target surface in the form of pressure spots. As a result of this, the air flowing in contact with the target surface experiences a damping potential, in due of which it gets more time and contact with the surface to dissipate heat.

Effect of Substrate and Process Parameters on the Gas-Substrate Convective Heat Transfer Coefficient During Cold Spraying

NASA Astrophysics Data System (ADS)

Mahdavi, Amirhossein; McDonald, André

2018-02-01

The final quality of cold-sprayed coatings can be significantly influenced by gas-substrate heat exchange, due to the dependence of the deposition efficiency of the particles on the substrate temperature distribution. In this study, the effect of the air temperature and pressure, as process parameters, and surface roughness and thickness, as substrate parameters, on the convective heat transfer coefficient of the impinging air jet was investigated. A low-pressure cold spraying unit was used to generate a compressed air jet that impinged on a flat substrate. A comprehensive mathematical model was developed and coupled with experimental data to estimate the heat transfer coefficient and the surface temperature of the substrate. The effect of the air total temperature and pressure on the heat transfer coefficient was studied. It was found that increasing the total pressure would increase the Nusselt number of the impinging air jet, while total temperature of the air jet had negligible effect on the Nusslet number. It was further found that increasing the roughness of the substrate enhanced the heat exchange between the impinging air jet and the substrate. As a result, higher surface temperatures on the rough substrate were measured. The study of the effect of the substrate thickness on the heat transfer coefficient showed that the Nusselt number that was predicted by the model was independent of the thickness of the substrate. The surface temperature profile, however, decreased in increasing radial distances from the stagnation point of the impinging jet as the thickness of the substrate increased. The results of the current study were aimed to inform on the influence and effect of substrate and process parameters on the gas-substrate heat exchange and the surface temperature of the substrate on the final quality of cold-sprayed coatings.

An investigation into a micro-sized droplet impinging on a surface with sharp wettability contrast

NASA Astrophysics Data System (ADS)

Lim, C. Y.; Lam, Y. C.

2014-10-01

An experimental investigation was conducted into a micro-sized droplet jetted onto a surface with sharp wettability contrast. The dynamics of micro-sized droplet impingement on a sharp wettability contrast surface, which is critical in inkjet printing technology, has not been investigated in the literature. Hydrophilic lines with line widths ranging from 27 to 53 µm, and contact angle ranging from 17° to 77°, were patterned on a hydrophobic surface with a contact angle of 107°. Water droplets with a diameter of 81 µm were impinged at various offset distances from the centre of the hydrophilic line. The evolution of the droplet upon impingement can be divided into three distinct phases, namely the kinematic phase, the translating phase where the droplet moves towards the centre of the hydrophilic line, and the conforming phase where the droplet spreads along the line. The key parameters affecting the conformability of the droplet to the hydrophilic line pattern are the ratio of the line width to the initial droplet diameter and the contact angle of the hydrophilic line. The droplet will only conform completely to the hydrophilic pattern if the line width is not overly small relative to the droplet and the contact angle of the hydrophilic line is sufficiently low. The impact offset distance does not affect the final shape and final location of the droplet, as long as part of the droplet touches the hydrophilic line upon impingement. This process has a significant impact on inkjet printing technology as high accuracy of inkjet droplet deposition and shape control can be achieved through wettability patterning.

Plume Impingement to the Lunar Surface: A Challenging Problem for DSMC

NASA Technical Reports Server (NTRS)

Lumpkin, Forrest; Marichalar, Jermiah; Piplica, Anthony

2007-01-01

The President's Vision for Space Exploration calls for the return of human exploration of the Moon. The plans are ambitious and call for the creation of a lunar outpost. Lunar Landers will therefore be required to land near predeployed hardware, and the dust storm created by the Lunar Lander's plume impingement to the lunar surface presents a hazard. Knowledge of the number density, size distribution, and velocity of the grains in the dust cloud entrained into the flow is needing to develop mitigation strategies. An initial step to acquire such knowledge is simulating the associated plume impingement flow field. The following paper presents results from a loosely coupled continuum flow solver/Direct Simulation Monte Carlo (DSMC) technique for simulating the plume impingement of the Apollo Lunar module on the lunar surface. These cases were chosen for initial study to allow for comparison with available Apollo video. The relatively high engine thrust and the desire to simulate interesting cases near touchdown result in flow that is nearly entirely continuum. The DSMC region of the flow field was simulated using NASA's DSMC Analysis Code (DAC) and must begin upstream of the impingement shock for the loosely coupled technique to succeed. It was therefore impossible to achieve mean free path resolution with a reasonable number of molecules (say 100 million) as is shown. In order to mitigate accuracy and performance issues when using such large cells, advanced techniques such as collision limiting and nearest neighbor collisions were employed. The final paper will assess the benefits and shortcomings of such techniques. In addition, the effects of plume orientation, plume altitude, and lunar topography, such as craters, on the flow field, the surface pressure distribution, and the surface shear stress distribution are presented.

Effect of impinging plate geometry on the self-excitation of subsonic impinging jets

NASA Astrophysics Data System (ADS)

Vinoth, B. R.; Rathakrishnan, E.

2011-11-01

In the generation of discrete tones by subsonic impinging jets, there exists a difference of opinion as how the feedback is achieved, i.e., the path of the feedback acoustic waves is whether inside the jet or outside the jet? The only available model (Tam and Ahuja model) for the prediction of an average subsonic jet impingement tone frequency assumes that the upstream part of the feedback loop is closed by an upstream propagating neutral wave of the jet. But, there is no information about the plate geometry in the model. The present study aims at understanding the effect of the plate geometry (size and co-axial hole in the plate) on the self-excitation process of subsonic impinging jets and the path of the acoustic feedback to the nozzle exit. The present results show that there is no effect of plate diameter on the frequency of the self-excitation. A new type of tones is generated for plates with co-axial hole (hole diameter is equal to nozzle exit diameter) for Mach numbers 0.9 and 0.95, in addition to the axisymmetric and helical mode tones observed for plates without co-axial hole. The stability results show that the Strouhal number of the least dispersive upstream propagating neutral waves match with the average Strouhal number of the new tones observed in the present experiments. The present study extends the validity of the model of Tam and Ahuja to a plate with co-axial hole (annular plate) and by doing so, we indirectly confirmed that the major acoustic feedback path to the nozzle exit is inside the jet.

Analysis of Dual Mobility Liner Rim Damage Using Retrieved Components and Cadaver Models.

PubMed

Nebergall, Audrey K; Freiberg, Andrew A; Greene, Meridith E; Malchau, Henrik; Muratoglu, Orhun; Rowell, Shannon; Zumbrunn, Thomas; Varadarajan, Kartik M

2016-07-01

The objective of this study was to assess the retentive rim of retrieved dual mobility liners for visible evidence of deformation from femoral neck contact and to use cadaver models to determine if anterior soft tissue impingement could contribute to such deformation. Fifteen surgically retrieved polyethylene liners were assessed for evidence of rim deformation. The average time in vivo was 31.4 months, and all patients were revised for reasons other than intraprosthetic dislocation. Liner interaction with the iliopsoas was studied visually and with fluoroscopy in cadaver specimens using a dual mobility system different than the retrieval study. For fluoroscopic visualization, a metal wire was sutured to the iliopsoas and wires were also embedded into grooves on the outer surface of the liner and the inner head. All retrievals showed evidence of femoral neck contact. The cadaver experiments showed that liner motion was impeded by impingement with the iliopsoas tendon in low flexion angles. When observing the hip during maximum hyperextension, 0°, 15°, and 30° of flexion, there was noticeable tenting of the iliopsoas caused by impingement with the liner. Liner rim deformation resulting from contact with the femoral neck likely begins during early in vivo function. The presence of deformation is indicative of a mechanism inhibiting mobility of the liner. The cadaver studies showed that liner motion could be impeded because of its impingement with the iliopsoas. Such soft tissue impingement may be one mechanism by which liner motion is routinely inhibited, which can result in load transfer from the neck to the rim. Copyright © 2015 Elsevier Inc. All rights reserved.

Outcomes of cup revision for ilio-psoas impingement after total hip arthroplasty: Retrospective study of 46 patients.

PubMed

Batailler, C; Bonin, N; M Wettstein; Nogier, A; Martres, S; Ollier, E; May, O; Lustig, S

2017-12-01

Impingement of the ilio-psoas tendon on the acetabular component is a cause of pain after total hip arthroplasty (THA). Studies of cup revision for ilio-psoas impingement (IPI) are scarce and limited in size. We therefore conducted a large multicentre retrospective study with the following objectives: to assess the effectiveness of cup replacement in resolving the impingement syndrome, to determine the frequency and nature of complications after cup revision for IPI, and to identify pre-operative factors associated with good outcomes of cup revision for IPI. Cup revision is effective in resolving the pain due to IPI in selected patients. This retrospective multicentre study included 46 patients who underwent cup revision because of IPI. Before the revision, 38 (83%) patients had prominence of the anterior cup rim (mean, 9.9±4.5mm (range, 2-22mm) by radiography and 35 (76%) had cup malposition (anteversion<10° and/or inclination>50°). Mean follow-up was 21months (range, 6months to 6 years) and no patient was lost to follow-up. Outcomes at last follow-up were assessed based on the Oxford Hip Score (OHS), patient satisfaction index, complications, and revisions. At last follow-up, 39 (85%) patients were satisfied with the revision procedure, a significant improvement versus baseline was noted in the OHS (mean, 43±6; range, 25-48; P<0.001), and 41 patients were free of pain during hip flexion (P<0.001 versus baseline). Complications occurred in 3 (6.5%) patients, but only one complication was severe (deep infection). Recurrent groin pain was reported by 4 (8.7%) patients at last follow-up. None of the factors studied predicted the outcome of revision surgery. Cup revision for IPI after THA is effective in relieving the groin pain in 80% of patients with anterior cup rim prominence and/or cup malposition. However, complications can occur. Tenotomy may be preferable when the diagnosis is in doubt and/or cup position is acceptable. IV, retrospective observational study. Published by Elsevier Masson SAS.

Configurable double-sided modular jet impingement assemblies for electronics cooling

DOEpatents

Zhou, Feng; Dede, Ercan Mehmet

2018-05-22

A modular jet impingement assembly includes an inlet tube fluidly coupled to a fluid inlet, an outlet tube fluidly coupled to a fluid outlet, and a modular manifold having a first distribution recess extending into a first side of the modular manifold, a second distribution recess extending into a second side of the modular manifold, a plurality of inlet connection tubes positioned at an inlet end of the modular manifold, and a plurality of outlet connection tubes positioned at an outlet end of the modular manifold. A first manifold insert is removably positioned within the first distribution recess, a second manifold insert is removably positioned within the second distribution recess, and a first and second heat transfer plate each removably coupled to the modular manifold. The first and second heat transfer plates each comprise an impingement surface.

Factors affecting the impingement angle of fixed- and mobile-bearing total knee replacements: a laboratory study.

PubMed

Walker, Peter S; Yildirim, Gokce; Sussman-Fort, Jon; Roth, Jonathan; White, Brian; Klein, Gregg R

2007-08-01

Maximum flexion-or impingement angle-is defined as the angle of flexion when the posterior femoral cortex impacts the posterior edge of the tibial insert. We examined the effects of femoral component placement on the femur, the slope angle of the tibial component, the location of the femoral-tibial contact point, and the amount of internal or external rotation. Posterior and proximal femoral placement, a more posterior femoral-tibial contact point, and a more tibial slope all increased maximum flexion, whereas rotation reduced it. A mobile-bearing knee gave results similar to those of the fixed-bearing knee, but there was no loss of flexion in internal or external rotation if the mobile bearing moved with the femur. In the absence of negative factors, a flexion angle of 150 degrees can be reached before impingement.

Development of an Impinging-jet Fuel-injection Valve Nozzle

NASA Technical Reports Server (NTRS)

Spanogle, J A; Hemmeter, G H

1931-01-01

During an investigation to determine the possibilities and limitations of a two-stroke-cycle engine and ignition, it was necessary to develop a fuel injection valve nozzle to produce a disk-shaped, well dispersed spray. Preliminary tests showed that two smooth jets impinging upon each other at an angle of 74 degrees gave a spray with the desired characteristics. Nozzles were built on this basis and, when used in fuel-injection valves, produced a spray that fulfilled the original requirements. The spray is so well dispersed that it can be carried along with an air stream of comparatively low velocity or entrained with the fuel jet from a round-hole orifice. The characteristics of the spray from an impinging-jet nozzle limits its application to situations where wide dispersion is required by the conditions in the engine cylinder and the combustion chamber.

Investigation of impingement region and wall jets formed by the interaction of high aspect ratio lift jets and a ground plane

NASA Technical Reports Server (NTRS)

Kotansky, D. R.; Glaze, L. W.

1978-01-01

Flow characteristics of impinging jets emanating from rectangular exit area converging nozzles of exit area aspect ratio four, six, and eight were investigated. Azimuthal distributions of wall jet radial momentum flux in the ground plane were strongly directional and sensitive to rectangular nozzle exit area aspect ratio, jet impingement angle, and height above ground, H/D. Effects of jet exit velocity profile nonuniformities were also investigated. Data from the single nozzle rectangular jet impringement investigations were incorporated into an existing VTOL aircraft ground flow field computer program. It is suggested that this program together with the Douglas Neumann program modified for V/STOL applications may be used for the analysis and prediction of flow fields and resulting forces and moments on multijet V/STOL aircraft hovering in ground effect.

The Effects of Crossflow on the Pressures and Lift Induced by the Fountain Generated Between Two Impinging Jets

NASA Technical Reports Server (NTRS)

Kuhn, Richard E.

1998-01-01

When a jet STOVL aircraft is hovering, or in a crossflow, while close to the ground wall jets flowing radially outward from the impingement points of the jets are generated. An upflow, or fountain, is generated where the wall jets from adjacent jets meet on the ground surface. The induced lift and suckdown generated by the impingement of the fountain on the lower surface of the configuration has been the subject of previous studies. This study analyzes the limited available pressure and force data on the effect of crossflow on the fountain induced lift and suckdown. The analysis includes the effects of jet spacing, height and operating conditions. However, it is limited to twin jet configurations of circular, vertical jets operating at subcritical nozzle pressure ratios over a fixed ground surface.

Survey of fish impingement at power plants in the United States. Volume II. Inland waters

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

Freeman, III, Richard F.; Sharma, Rajendra K.

1977-03-01

Impingement of fish at cooling-water intakes of 33 power plants located on inland waters other than the Great Lakes has been surveyed and data are presented. Descriptions of site, plant, and intake design and operation are provided. Reports in this volume summarize impingement data for individual plants in tabular and histogram formats. Information was available from differing sources such as the utilities themselves, public documents, regulatory agencies, and others. Thus, the extent of detail in the reports varies greatly from plant to plant. Histogram preparation involved an extrapolation procedure that has inadequacies. The reader is cautioned in the use ofmore » information presented in this volume to determine intake-design acceptability or intensity of impacts on ecosystems. No conclusions are presented herein; data comparisons are made in Volume IV.« less

Vortex rings impinging on permeable boundaries

NASA Astrophysics Data System (ADS)

Mujal-Colilles, Anna; Dalziel, Stuart B.; Bateman, Allen

2015-01-01

Experiments with vortex rings impinging permeable and solid boundaries are presented in order to investigate the influence of permeability. Utilizing Particle Image Velocimetry, we compared the behaviour of a vortex ring impinging four different reticulated foams (with permeability k ˜ 26 - 85 × 10-8 m2) and a solid boundary. Results show how permeability affects the stretching phenomena of the vortex ring and the formation and evolution of the secondary vortex ring with opposite sign. Moreover, permeability also affects the macroscopic no-slip boundary condition found on the solid boundary, turning it into an apparent slip boundary condition for the most permeable boundary. The apparent slip-boundary condition and the flux exchange between the ambient fluid and the foam are jointly responsible for both the modified formation of the secondary vortex and changes on the vortex ring diameter increase.

Experimental Database with Baseline CFD Solutions: 2-D and Axisymmetric Hypersonic Shock-Wave/Turbulent-Boundary-Layer Interactions

NASA Technical Reports Server (NTRS)

Marvin, Joseph G.; Brown, James L.; Gnoffo, Peter A.

2013-01-01

A database compilation of hypersonic shock-wave/turbulent boundary layer experiments is provided. The experiments selected for the database are either 2D or axisymmetric, and include both compression corner and impinging type SWTBL interactions. The strength of the interactions range from attached to incipient separation to fully separated flows. The experiments were chosen based on criterion to ensure quality of the datasets, to be relevant to NASA's missions and to be useful for validation and uncertainty assessment of CFD Navier-Stokes predictive methods, both now and in the future. An emphasis on datasets selected was on surface pressures and surface heating throughout the interaction, but include some wall shear stress distributions and flowfield profiles. Included, for selected cases, are example CFD grids and setup information, along with surface pressure and wall heating results from simulations using current NASA real-gas Navier-Stokes codes by which future CFD investigators can compare and evaluate physics modeling improvements and validation and uncertainty assessments of future CFD code developments. The experimental database is presented tabulated in the Appendices describing each experiment. The database is also provided in computer-readable ASCII files located on a companion DVD.

Optical force rectifiers based on PT-symmetric metasurfaces

NASA Astrophysics Data System (ADS)

Alaee, Rasoul; Gurlek, Burak; Christensen, Johan; Kadic, Muamer

2018-05-01

We introduce here the concept of optical force rectifier based on parity-time symmetric metasurfaces. Directly linked to the properties of non-Hermitian systems engineered by balanced loss and gain constituents, we show that light can exert asymmetric pulling or pushing forces on metasurfaces depending on the direction of the impinging light. This generates a complete force rectification in the vicinity of the exceptional point. Our findings have the potential to spark the design of applications in optical manipulation where the forces, strictly speaking, act unidirectionally.

Magnetic Resonance Imaging of Nonneoplastic Musculoskeletal Pathologies in the Pelvis.

PubMed

Alapati, Sindhura; Wadhwa, Vibhor; Komarraju, Aparna; Guidry, Carey; Pandey, Tarun

2017-06-01

Musculoskeletal pathologies in the pelvis encompass a wide variety of lesions including femoroacetabular impingement, athletic pubalgia, ischiofemoral impingement, and apophyseal avulsion injuries. Magnetic resonance imaging is the noninvasive imaging modality of choice for the diagnosis and management of these lesions. In this article, the authors discuss the nonneoplastic musculoskeletal lesions in the pelvis, with illustrations and relevant case examples. Copyright © 2017 Elsevier Inc. All rights reserved.

Zero secular torque on asteroids from impinging solar photons in the YORP effect: A simple proof

NASA Astrophysics Data System (ADS)

Rubincam, David Parry; Paddack, Stephen J.

2010-10-01

YORP torques, where "YORP" stands for "Yarokovsky-O'Keefe-Radzievskii-Paddack," arise mainly from sunlight reflected off a Solar System object and the infrared radiation emitted by it. We show here, through the most elementary demonstration that we can devise, that secular torques from impinging solar photons are generally negligible and thus cause little secular evolution of an asteroid's obliquity or spin rate.

Outcome of pinning in patients with slipped capital femoral epiphysis: risk factors associated with avascular necrosis, chondrolysis, and femoral impingement.

PubMed

Ulici, Alexandru; Carp, Madalina; Tevanov, Iulia; Nahoi, Catalin Alexandru; Sterian, Alin Gabriel; Cosma, Dan

2018-06-01

Objective This study aimed to assess the principal risk factors that could lead to the most common long-term complications of slipped capital femoral epiphysis, such as avascular necrosis, chondrolysis, and hip impingement. Methods We conducted a single-centre, retrospective study and evaluated patients (70 patients, 81 hips) who were treated for slipped capital femoral epiphysis from 2010 to 2015 and who underwent pinning. We measured the severity of displacement radiologically using the Southwick angle. Postoperative radiographs were evaluated for the most frequent long-term complications of avascular necrosis (AVN), chondrolysis, and femoral acetabular impingement (FAI). Results We found seven cases of AVN, 14 cases of chondrolysis, and 31 hips had an α angle of 60°. Sex, ambulation, and symptoms did not affect development of these complications. Patients with a normal weight were almost two times more likely to develop FAI. Patients with moderate and severe slips had a similar percentage of AVN. In severe slips, 85.7% of patients had an α angle higher than 60°. Conclusions This study shows that severe slips have a higher risk of developing AVN and hip impingement. Every patient who suffers from SCFE (even the mildest forms) should be regularly checked for FAI.

Reactive impinging-flow technique for polymer-electrolyte-fuel-cell electrode-defect detection

DOE PAGES

Zenyuk, Iryna V.; Englund, Nicholas; Bender, Guido; ...

2016-09-29

Reactive impinging flow (RIF) is a novel quality-control method for defect detection (i.e., reduction in Pt catalyst loading) in gas-diffusion electrodes (GDEs) on weblines. The technique uses infrared thermography to detect temperature of a nonflammable (<4% H 2) reactive mixture of H 2/O 2 in N 2 impinging and reacting on a Pt catalytic surface. In this article, different GDE size defects (with catalyst-loading reductions of 25, 50, and 100%) are detected at various webline speeds (3.048 and 9.144 m min -1) and gas flowrates (32.5 or 50 standard L min -1). Furthermore, a model is developed and validated formore » the technique, and it is subsequently used to optimize operating conditions and explore the applicability of the technique to a range of defects. The model suggests that increased detection can be achieved by recting more of the impinging H 2, which can be accomplished by placing blocking substrates on the top, bottom, or both of the GDE; placing a substrate on both results in a factor of four increase in the temperature differential, which is needed for smaller defect detection. Lastly, overall, the RIF technique is shown to be a promising route for in-line, high-speed, large-area detection of GDE defects on moving weblines.« less

Reactive impinging-flow technique for polymer-electrolyte-fuel-cell electrode-defect detection

NASA Astrophysics Data System (ADS)

Zenyuk, Iryna V.; Englund, Nicholas; Bender, Guido; Weber, Adam Z.; Ulsh, Michael

2016-11-01

Reactive impinging flow (RIF) is a novel quality-control method for defect detection (i.e., reduction in Pt catalyst loading) in gas-diffusion electrodes (GDEs) on weblines. The technique uses infrared thermography to detect temperature of a nonflammable (<4% H2) reactive mixture of H2/O2 in N2 impinging and reacting on a Pt catalytic surface. In this paper, different GDE size defects (with catalyst-loading reductions of 25, 50, and 100%) are detected at various webline speeds (3.048 and 9.144 m min-1) and gas flowrates (32.5 or 50 standard L min-1). Furthermore, a model is developed and validated for the technique, and it is subsequently used to optimize operating conditions and explore the applicability of the technique to a range of defects. The model suggests that increased detection can be achieved by recting more of the impinging H2, which can be accomplished by placing blocking substrates on the top, bottom, or both of the GDE; placing a substrate on both results in a factor of four increase in the temperature differential, which is needed for smaller defect detection. Overall, the RIF technique is shown to be a promising route for in-line, high-speed, large-area detection of GDE defects on moving weblines.

CO Emission from an Impinging Non-Premixed Flame

PubMed Central

Chien, Y.C.; Escofet-Martin, D.; Dunn-Rankin, D.

2017-01-01

Carbon monoxide (CO) results from the incomplete oxidation of hydrocarbon fuels. While CO can be desirable in some syngas processes, it is a dangerous emission from fires, gas heaters, gas stoves, or furnaces where insufficient oxygen in the core reaction prevents complete oxidation of fuel to carbon dioxide and water, particularly when the reaction is interrupted by interaction with relatively cool solid boundaries. This research examines the physico-thermo-chemical processes responsible for carbon monoxide release from a small laminar non-premixed methane/air flame impinging on a nearby surface. We measure the changes in CO emission as correlated with variations in flame structure observed using planar laser induced fluorescence (PLIF of OH and 2-photon CO), and two-line OH PLIF thermometry, as a function of burner-to-plate distance. In particular, this work combines the use of OH and CO PLIF, and PLIF thermometry to describe the relative locations of the CO rich region, the peak heat release zone as indicated by chemiluminescence and OH gradients, and the extended oxidative zone in the impinging flames. The results show that CO release correlates strongly with stagnating flow-driven changes in the location and extent of high concentration regions of OH in surface-impinging diffusion flames. PMID:28989179

Physical examination tests for the diagnosis of femoroacetabular impingement. A systematic review.

PubMed

Pacheco-Carrillo, Aitana; Medina-Porqueres, Ivan

2016-09-01

Numerous clinical tests have been proposed to diagnose FAI, but little is known about their diagnostic accuracy. To summarize and evaluate research on the accuracy of physical examination tests for diagnosis of FAI. A search of the PubMed, SPORTDiscus and CINAHL databases was performed. Studies were considered eligible if they compared the results of physical examination tests to those of a reference standard. Methodological quality and internal validity assessment was performed by two independent reviewers using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. The systematic search strategy revealed 298 potential articles, five of which articles met the inclusion criteria. After assessment using the QUADAS score, four of the five articles were of high quality. Clinical tests included were Impingement sign, IROP test (Internal Rotation Over Pressure), FABER test (Flexion-Abduction-External Rotation), Stinchfield/RSRL (Resisted Straight Leg Raise) test, Scour test, Maximal squat test, and the Anterior Impingement test. IROP test, impingement sign, and FABER test showed the most sensitive values to identify FAI. The diagnostic accuracy of physical examination tests to assess FAI is limited due to its heterogenecity. There is a strong need for sound research of high methodological quality in this area. Copyright © 2016 Elsevier Ltd. All rights reserved.

Heat transfer and material temperature conditions in the leading edge area of impingement-cooled turbine vanes

NASA Astrophysics Data System (ADS)

Berg, H. P.; Pfaff, K.; Hennecke, D. K.

The resultant effects on the cooling effectiveness at the leading edge area of an impingement-cooled turbine vane by varying certain geometrical parameters is described with reference to local internal heat transfer coefficients determined from experiment and temperature calculations. The local heat transfer on the cooling-air side is determined experimentally with the aid of the analogy between heat- and mass transfer. The impingement cooling is provided from an inserted sheet-metal containing a single row of holes. The Reynolds Number and several of the cooling geometry parameters were varied. The results demonstrate the high local resolution of the method of measurement, which allows improved analytical treatment of the leading-edge cooling configuration. These experiments also point to the necessity of not always performing model tests under idealized conditions. This becomes very clear in the case of the tests performed on an application-oriented impingement-cooling configuration like that often encountered in engine manufacture. In conclusion, as an example, temperature calculations are employed to demonstrate the effect on the cooling effectiveness of varying the distances between insert and inner surface of the leading edge. It shows how the effectiveness of the leading edge cooling can be increased by simple geometrical measures, which results in a considerable improvement in service life.

Time effect of erosion by solid particle impingement on ductile materials

NASA Technical Reports Server (NTRS)

Rao, P. V.; Buckley, D. H.

1983-01-01

Erosion and morphological studies of several metals and alloys eroded by normal impingement jets of spherical glass beads and angular crushed-glass erodent particles were conducted. Erosion morphology (the width, depth, and width-depth ratio of the pit) was studied in order to fully investigate the effect of time on erosion rate. The eroded surfaces were studied with a scanning electron microscope, and surface profiles were measured with a profilometer. A large amount of experimental data reported in the literature was also analyzed in order to understand the effect of variables such as the type of device, the erodent particle size and shape, the impact velocity, and the abrasive charge on erosion-rate-versus-time curves. In the present experiments the pit-width-versus-time or pit-depth-versus-time curves were similar to erosion-versus-time curves for glass-bead impingement. The pit-depth-rate-versus-time curves were similar to erosion-rate-versus-time curves for crushed-glass impingement. Analysis of experimental data with two forms of glass resulted in four types of erosion-rate-versus-time curves: (1) incubation, acceleration, and steady-state periods (type I), (2) incubation, acceleration, deceleration, and steady-state periods (type III), (3) incubation, acceleration, peak rate, and deceleration periods (type IV), and (4) incubation, acceleration, steady-state, and deceleration periods (type V).

Simulations of Ground and Space-Based Oxygen Atom Experiments

NASA Technical Reports Server (NTRS)

Finchum, A. (Technical Monitor); Cline, J. A.; Minton, T. K.; Braunstein, M.

2003-01-01

A low-earth orbit (LEO) materials erosion scenario and the ground-based experiment designed to simulate it are compared using the direct-simulation Monte Carlo (DSMC) method. The DSMC model provides a detailed description of the interactions between the hyperthermal gas flow and a normally oriented flat plate for each case. We find that while the general characteristics of the LEO exposure are represented in the ground-based experiment, multi-collision effects can potentially alter the impact energy and directionality of the impinging molecules in the ground-based experiment. Multi-collision phenomena also affect downstream flux measurements.

Computation of Feedback Aeroacoustic System by the CE/SE Method

NASA Technical Reports Server (NTRS)

Loh, Ching Y.; Wang, Xiao Y.; Chang, Sin-Chung; Jorgenson, Philip C. E.

2000-01-01

It is well known that due to vortex shedding in high speed flow over cutouts, cavities, and gaps, intense noise may be generated. Strong tonal oscillations occur in a feedback cycle in which the vortices shed from the upstream edge of the cavity convect downstream and impinge on the cavity lip, generating acoustic waves that propagate upstream to excite new vortices. Numerical simulation of such a complicated process requires a scheme that can: (1) resolve acoustic waves with low dispersion and numerical dissipation, (2) handle nonlinear and discontinuous waves (e.g. shocks), and (3) have an effective (near field) nonreflecting boundary condition (NRBC). The new space time conservation element and solution element method, or CE/SE for short, is a numerical method that meets the above requirements.

A perfect Fresnel acoustic reflector implemented by a Fano-resonant metascreen

NASA Astrophysics Data System (ADS)

Amin, M.; Siddiqui, O.; Farhat, M.; Khelif, A.

2018-04-01

We propose a perfectly reflecting acoustic metasurface which is designed by replacing the curved segments of the traditional Fresnel reflector by flat Fano-resonant sub-wavelength unit cells. To preserve the original Fresnel focusing mechanism, the unit cell phase follows a specific phase profile which is obtained by applying the generalized Snell's law and Fermat's principle. The reflected curved phase fronts are thus created at the air-metasurface boundary by tailoring the metasurface dispersion as dictated by Huygens' principle. Since the unit cells are implemented by sub-wavelength double slit-shaped cavity resonators, the impinging sound waves are perfectly reflected producing acoustic focusing with negligible absorption. We use plane-wave solution and full-wave simulations to demonstrate the focusing effects. The simulation results closely follow the analytical predictions.

Frequency modulation at a moving material interface and a conservation law for wave number. [acoustic wave reflection and transmission

NASA Technical Reports Server (NTRS)

Kleinstein, G. G.; Gunzburger, M. D.

1976-01-01

An integral conservation law for wave numbers is considered. In order to test the validity of the proposed conservation law, a complete solution for the reflection and transmission of an acoustic wave impinging normally on a material interface moving at a constant speed is derived. The agreement between the frequency condition thus deduced from the dynamic equations of motion and the frequency condition derived from the jump condition associated with the integral equation supports the proposed law as a true conservation law. Additional comparisons such as amplitude discontinuities and Snells' law in a moving media further confirm the stated proposition. Results are stated concerning frequency and wave number relations across a shock front as predicted by the proposed conservation law.

Numerical modeling of spray combustion with an advanced VOF method

NASA Technical Reports Server (NTRS)

Chen, Yen-Sen; Shang, Huan-Min; Shih, Ming-Hsin; Liaw, Paul

1995-01-01

This paper summarizes the technical development and validation of a multiphase computational fluid dynamics (CFD) numerical method using the volume-of-fluid (VOF) model and a Lagrangian tracking model which can be employed to analyze general multiphase flow problems with free surface mechanism. The gas-liquid interface mass, momentum and energy conservation relationships are modeled by continuum surface mechanisms. A new solution method is developed such that the present VOF model can be applied for all-speed flow regimes. The objectives of the present study are to develop and verify the fractional volume-of-fluid cell partitioning approach into a predictor-corrector algorithm and to demonstrate the effectiveness of the present approach by simulating benchmark problems including laminar impinging jets, shear coaxial jet atomization and shear coaxial spray combustion flows.

Wake Closure Characteristics and Afterbody Heating on a Mars Sample Return Orbiter

NASA Technical Reports Server (NTRS)

Horvath, Thomas J.; Cheatwood, McNeil F.; Wilmoth, Richard G.; Alter, Stephen J.

2002-01-01

Aeroheating wind-tunnel tests were conducted on a 0.028 scale model of an orbiter concept considered for a possible Mars sample return mission. The primary experimental objectives were to characterize hypersonic near wake closure and determine if shear layer impingement would occur on the proposed orbiter afterbody at incidence angles necessary for a Martian aerocapture maneuver. Global heat transfer mappings, surface streamline patterns, and shock shapes were obtained in the NASA Langley 20-Inch Mach 6 Air and CF4 Tunnels for post-normal shock Reynolds numbers (based on forebody diameter) ranging from 1,400 to 415,000, angles of attack ranging from -5 to 10 degrees at 0, 3, and 6 degree sideslip, and normal-shock density ratios of 5 and 12. Laminar, transitional, and turbulent shear layer impingement on the cylindrical afterbody was inferred from the measurements and resulted in a localized heating maximum that ranged from 40 to 75 percent of the reference forebody stagnation point heating. Comparison of laminar heating prediction to experimental measurement along the orbiter afterbody highlight grid alignment challenges associated with numerical simulation of three- dimensional separated wake flows. Predicted values of a continuum breakdown parameter revealed significant regions of non-continuum flow downstream of the flow separation at the MSRO shoulder and in the region of the reattachment shock on the afterbody. The presence of these regions suggest that the Navier-Stokes predictions at the laminar wind-tunnel condition may encounter errors in the numerical calculation of the wake shear layer development and impingement due to non-continuum effects.

Long-term predictive capability of erosion models

NASA Technical Reports Server (NTRS)

Veerabhadra, P.; Buckley, D. H.

1983-01-01

A brief overview of long-term cavitation and liquid impingement erosion and modeling methods proposed by different investigators, including the curve-fit approach is presented. A table was prepared to highlight the number of variables necessary for each model in order to compute the erosion-versus-time curves. A power law relation based on the average erosion rate is suggested which may solve several modeling problems.

THE DETERMINATION OF MERCURY SPECIES AND MULTIPLE METALS IN COAL COMBUSTION EMISSIONS USING IODINE-BASED IMPINGERS AND DIRECT INJECTION NEBULIZATION - INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY ANALYSIS

EPA Science Inventory

Mercury (Hg) emissions from coal utilities are difficult to control. Hg eludes capture by most air pollution control devices (APCDs). To determine the gaseous Hg species in stack gases, U.S. EPA Method 5 type sampling is used. In this type of sampling a hole is drilled into th...

Empirical relations for cavitation and liquid impingement erosion processes

NASA Technical Reports Server (NTRS)

Rao, P. V.; Buckley, D. H.

1984-01-01

A unified power-law relationship between average erosion rate and cumulative erosion is presented. Extensive data analyses from venturi, magnetostriction (stationary and oscillating specimens), liquid drop, and jet impact devices appear to conform to this relation. A normalization technique using cavitation and liquid impingement erosion data is also presented to facilitate prediction. Attempts are made to understand the relationship between the coefficients in the power-law relationships and the material properties.

Zero Secular Torque on Asteroids from Impinging Solar Photons in the YORP Effect: A Simple Proof

NASA Technical Reports Server (NTRS)

Rubincam, David Perry; Paddack, Stephen J.

2010-01-01

YORP torques, where "YORP" stands for "Yarokovsky-O'Keefe-Radzievskii-Paddack." arise mainly from sun light reflected off a Solar System object and the infrared radiation emi tted by it. We show here, through the most elementary demonstration that we Can devise, that secular torques from impinging solar photons are generally negligible and thus cause little secular evolution of an asteroid's obliquity or spin rate.

Gas turbine bucket with impingement cooled platform

DOEpatents

Jones, Raphael Durand

2002-01-01

In a turbine bucket having an airfoil portion and a root portion, with a substantially planar platform at an interface between the airfoil portion and root portion, a platform cooling arrangement including at least one bore in the root portion and at least one impingement cooling tube seated in the bore, the tube extending beyond the bore with an outlet in close proximity to a targeted area on an underside of the platform.

Open and Arthroscopic Surgical Treatment of Femoroacetabular Impingement

PubMed Central

Kuhns, Benjamin D.; Frank, Rachel M.; Pulido, Luis

2015-01-01

Femoroacetabular impingement (FAI) is a common cause of hip pain, and when indicated, can be successfully managed through open surgery or hip arthroscopy. The goal of this review is to describe the different approaches to the surgical treatment of FAI. We present the indications, surgical technique, rehabilitation, and complications associated with (1) open hip dislocation, (2) reverse periacetabular osteotomy, (3) the direct anterior “mini-open” approach, and (4) arthroscopic surgery for FAI. PMID:26697431

Range of Hip Joint Motion Is Correlated With MRI-Verified Cam Deformity in Adolescent Elite Skiers

PubMed Central

Agnvall, Cecilia; Swärd Aminoff, Anna; Todd, Carl; Jonasson, Pall; Thoreson, Olof; Swärd, Leif; Karlsson, Jon; Baranto, Adad

2017-01-01

Background: Radiologically verified cam-type femoroacetabular impingement (FAI) has been shown to correlate with reduced internal rotation, reduced passive hip flexion, and a positive anterior impingement test. Purpose: To validate how a clinical examination of the hip joint correlates with magnetic resonance imaging (MRI)–verified cam deformity in adolescents. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The sample group consisted of 102 adolescents with the mean age 17.7 ± 1.4 years. The hip joints were examined using MRI for measurements of the presence of cam (α-angle ≥55°) and clinically for range of motion (ROM) in both supine and sitting positions. The participants were divided into a cam and a noncam group based on the results of the MRI examination. Passive hip flexion, internal rotation, anterior impingement, and the FABER (flexion, abduction, and external rotation) test were used to test both hips in the supine position. With the participant sitting, the internal/external rotation of the hip joint was measured in 3 different positions of the pelvis (neutral, maximum anteversion, and retroversion) and lumbar spine (neutral, maximum extension, and flexion). Results: Differences were found between the cam and noncam groups in terms of the anterior impingement test (right, P = .010; left, P = .006), passive supine hip flexion (right: mean, 5°; cam, 117°; noncam, 122° [P = .05]; and left: mean, 8.5°; cam, 116°; noncam, 124.5° [P = .001]), supine internal rotation (right: mean, 4.9°; cam, 24°; noncam, 29° [P = .022]; and left: mean, 4.8°; cam, 26°; noncam, 31° [P = .028]), sitting internal rotation with the pelvis and lumbar spine in neutral (right: mean, 7.95°; cam, 29°; noncam, 37° [P = .001]; and left: mean, 6.5°; cam, 31.5°; noncam, 38° [P = .006]), maximum anteversion of the pelvis and extension of the lumbar spine (right: mean, 5.2°; cam, 20°; noncam, 25° [P = .004]; and left: mean, 5.85°; cam, 20.5; noncam, 26.4° [P = .004]), and maximum retroversion of the pelvis and flexion of the spine (right: mean, 8.4°; cam, 32.5°; noncam, 41° [P = .001]; and left: mean, 6.2°; cam, 36°; noncam, 42.3° [P = .012]). The cam group had reduced ROM compared with the noncam group in all clinical ROM measures. Conclusion: The presence of cam deformity on MRI correlates with reduced internal rotation in the supine and sitting positions, passive supine hip flexion, and the impingement test in adolescents. PMID:28695136

Self-cleaning of Surfaces: the Role of Surface Wettability and Dust Types

NASA Astrophysics Data System (ADS)

Quan, Yun-Yun; Zhang, Li-Zhi; Qi, Rong-Hui; Cai, Rong-Rong

2016-12-01

The self-cleaning property is usually connected to superhydrophobic surfaces (SHSs) where the dust particles can be easily removed by the rolling motion of droplets. It seems that superhydrophobicity (its durability is questionable nowadays) is a necessity. However here, it is disclosed that self-cleaning can also be realized on an ordinary surface by droplet impinging. The effects of surface wettability and the types of dust particles are considered. The self-cleaning is realized by two steps: (1) the pickup of particles by the water-air interface of an impinging droplet, (2) the release of the impinging droplets from the surface. It can be observed that only the trailing edges of the droplets can pick up particles when the droplets recoil from the inclined surfaces. The hydrophilic surface can also achieve self-cleaning under some conditions. This interesting finding may be helpful for the successful implementation of self-cleaning with common surfaces.

Water Droplet Impingement on Simulated Glaze, Mixed, and Rime Ice Accretions

NASA Technical Reports Server (NTRS)

Papadakis, Michael; Rachman, Arief; Wong, See-Cheuk; Yeong, Hsiung-Wei; Hung, Kuohsing E.; Vu, Giao T.; Bidwell, Colin S.

2007-01-01

Water droplet impingement data were obtained at the NASA Glenn Icing Research Tunnel (IRT) for a 36-in. chord NACA 23012 airfoil with and without simulated ice using a dye-tracer method. The simulated ice shapes were defined with the NASA Glenn LEWICE 2.2 ice accretion program and including one rime, four mixed and five glaze ice shapes. The impingement experiments were performed with spray clouds having median volumetric diameters of 20, 52, 111, 154, and 236 micron. Comparisons to the experimental data were generated which showed good agreement for the rime and mixed shapes at lower drop sizes. For larger drops sizes LEWICE 2.2 over predicted the collection efficiencies due to droplet splashing effects which were not modeled in the program. Also for the more complex glaze ice shapes interpolation errors resulted in the over prediction of collection efficiencies in cove or shadow regions of ice shapes.

A turbulent plane jet impinging nearby and far from a flat plate

NASA Astrophysics Data System (ADS)

Maurel, S.; Solliec, C.

Plane air jets presenting an impact find applications in many industrial devices. They can be found in installations of heating, cooling or drying, cleaning, pulverization, or containment of polluted environments. Other applications can be found in the ventilation of buildings. The correct design of these kinds of installations requires thorough knowledge of the structure of the jet from the cinematic point of view. With this intention a test bench with variable geometry was developed. Then, using laser Doppler velocimetry (LDV) and particle image velocimetry (PIV), it is possible to analyze the development of the jet for various geometrical and cinematic configurations. It appears that the development of the jet is independent of the Reynolds number, and the velocity decrease in the developed and impinging zones can be characterized by using very simple laws. Furthermore, by PIV visualization of the impinging zone, it has been possible to highlight the causes of mass transfer through the jet.

Turbine airfoil with laterally extending snubber having internal cooling system

DOEpatents

Scribner, Carmen Andrew; Messmann, Stephen John; Marsh, Jan H.

2016-09-06

A turbine airfoil usable in a turbine engine and having at least one snubber with a snubber cooling system positioned therein and in communication with an airfoil cooling system is disclosed. The snubber may extend from the outer housing of the airfoil toward an adjacent turbine airfoil positioned within a row of airfoils. The snubber cooling system may include an inner cooling channel separated from an outer cooling channel by an inner wall. The inner wall may include a plurality of impingement cooling orifices that direct impingement fluid against an outer wall defining the outer cooling channel. In one embodiment, the cooling fluids may be exhausted from the snubber, and in another embodiment, the cooling fluids may be returned to the airfoil cooling system. Flow guides may be positioned in the outer cooling channel, which may reduce cross-flow by the impingement orifices, thereby increasing effectiveness.