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Sample records for aerodynamic heating rates

  1. A Visual Technique for Determining Qualitative Aerodynamic Heating Rates on Complex Configurations

    NASA Technical Reports Server (NTRS)

    Stainback, P. Calvin

    1960-01-01

    An experimental investigation was conducted at a test-section Mach number of 4.95 and a stagnation temperature of 400 F to evaluate a visual technique for obtaining qualitative aerodynamic heat-transfer data on complex configurations.This technique utilized a temperature-sensetive paint indicated that this technique was satisfactory for determining qualitative heat-transfer rates on various bodies, some of which exhibited complex flow patterns. The results obtained have been found useful to guide the instrumentation of quantitative heat-transfer models, to supplement quantitative heat-transfer measurements, and to make preliminary heat-transfer studies for new configurations.

  2. A Visual Technique for Determining Qualitative Aerodynamic Heating Rates on Complex Configurations

    NASA Technical Reports Server (NTRS)

    Stainback, P. Calvin

    1960-01-01

    An experimental investigation was conducted at a test-section Mach number of 4.95 and a stagnation temperature of 400 F to evaluate a visual technique for obtaining qualitative aerodynamic heat-transfer data on complex configurations.This technique utilized a temperature-sensetive paint indicated that this technique was satisfactory for determining qualitative heat-transfer rates on various bodies, some of which exhibited complex flow patterns. The results obtained have been found useful to guide the instrumentation of quantitative heat-transfer models, to supplement quantitative heat-transfer measurements, and to make preliminary heat-transfer studies for new configurations.

  3. Large carbon cluster thin film gauges for measuring aerodynamic heat transfer rates in hypersonic shock tunnels

    NASA Astrophysics Data System (ADS)

    Srinath, S.; Reddy, K. P. J.

    2015-02-01

    Different types of Large Carbon Cluster (LCC) layers are synthesized by a single-step pyrolysis technique at various ratios of precursor mixture. The aim is to develop a fast responsive and stable thermal gauge based on a LCC layer which has relatively good electrical conduction in order to use it in the hypersonic flow field. The thermoelectric property of the LCC layer has been studied. It is found that these carbon clusters are sensitive to temperature changes. Therefore suitable thermal gauges were developed for blunt cone bodies and were tested in hypersonic shock tunnels at a flow Mach number of 6.8 to measure aerodynamic heating. The LCC layer of this thermal gauge encounters high shear forces and a hostile environment for test duration in the range of a millisecond. The results are favorable to use large carbon clusters as a better sensor than a conventional platinum thin film gauge in view of fast responsiveness and stability.

  4. Aerodynamic pressures and heating rates on surfaces between split elevons at Mach 6.6

    NASA Technical Reports Server (NTRS)

    Hunt, L. Roane

    1988-01-01

    An aerothermal study was performed in the Langley 8-Foot High Temperature Tunnel at Mach number 6.6 to define the pressures and heating rates on the surfaces between split elevons similar to those used on the Space Shuttle. Tests were performed with both laminar and turbulent boundary layers on the wing surface upstream of the elevons. The flow in the chordwise gap between the elevons was characterized by flow separation at the gap entrance and flow reattachment at a depth into the gap inversely proportional to the gap width. The gap pressure and heating rate increased significantly with decrease of elevon gap width, and the maximum gap heating rate was proportional to the maximum gap pressure. Correlation of the present results indicate that the gap heating was directly proportional to the elevon windward surface pressure and was not dependent upon whether the boundary layer on the windward elevon surface was laminar or turbulent.

  5. Aerodynamic heating in hypersonic flows

    NASA Technical Reports Server (NTRS)

    Reddy, C. Subba

    1993-01-01

    Aerodynamic heating in hypersonic space vehicles is an important factor to be considered in their design. Therefore the designers of such vehicles need reliable heat transfer data in this respect for a successful design. Such data is usually produced by testing the models of hypersonic surfaces in wind tunnels. Most of the hypersonic test facilities at present are conventional blow-down tunnels whose run times are of the order of several seconds. The surface temperatures on such models are obtained using standard techniques such as thin-film resistance gages, thin-skin transient calorimeter gages and coaxial thermocouple or video acquisition systems such as phosphor thermography and infrared thermography. The data are usually reduced assuming that the model behaves like a semi-infinite solid (SIS) with constant properties and that heat transfer is by one-dimensional conduction only. This simplifying assumption may be valid in cases where models are thick, run-times short, and thermal diffusivities small. In many instances, however, when these conditions are not met, the assumption may lead to significant errors in the heat transfer results. The purpose of the present paper is to investigate this aspect. Specifically, the objectives are as follows: (1) to determine the limiting conditions under which a model can be considered a semi-infinite body; (2) to estimate the extent of errors involved in the reduction of the data if the models violate the assumption; and (3) to come up with correlation factors which when multiplied by the results obtained under the SIS assumption will provide the results under the actual conditions.

  6. Shuttle system ascent aerodynamic and plume heating

    NASA Technical Reports Server (NTRS)

    Foster, L. D.; Greenwood, T. F.; Lee, D. B.

    1985-01-01

    The shuttle program provided a challenge to the aerothermodynamicist due to the complexity of the flow field around the vehicle during ascent, since the configuration causes multiple shock interactions between the elements. Wind tunnel tests provided data for the prediction of the ascent design heating environment which involves both plume and aerodynamic heating phenomena. The approach for the heating methodology based on ground test firings and the use of the wind tunnel data to formulate the math models is discussed.

  7. Turbine disk cavity aerodynamics and heat transfer

    NASA Technical Reports Server (NTRS)

    Johnson, B. V.; Daniels, W. A.

    1992-01-01

    Experiments were conducted to define the nature of the aerodynamics and heat transfer for the flow within the disk cavities and blade attachments of a large-scale model, simulating the Space Shuttle Main Engine (SSME) turbopump drive turbines. These experiments of the aerodynamic driving mechanisms explored the following: (1) flow between the main gas path and the disk cavities; (2) coolant flow injected into the disk cavities; (3) coolant density; (4) leakage flows through the seal between blades; and (5) the role that each of these various flows has in determining the adiabatic recovery temperature at all of the critical locations within the cavities. The model and the test apparatus provide close geometrical and aerodynamic simulation of all the two-stage cavity flow regions for the SSME High Pressure Fuel Turbopump and the ability to simulate the sources and sinks for each cavity flow.

  8. Booster aerodynamic heating: Test support

    NASA Technical Reports Server (NTRS)

    Engel, C. D.; Reardon, J. E.; Fuller, C. E.

    1974-01-01

    Several technical areas were encompassed in providing support for booster thermal environment test work. These areas included: (1) cavity flow heating, (2) rarefied flow heating, and (3) impulse operated model research and testing. Cavity flow heating problems were studied with respect to the proposed altitude control motors for the space shuttle. Available literature on this subject was reviewed and analytical predictive methods were summarized for use in planning testing work. Rarefied flow heating data was reviewed and correlated. The study showed the importance of considering rarefied flow conditions in launch thermal environment prediction. Impulse operated model research and testing was conducted to provide a basis for understanding and designing such models for booster thermal environment testing.

  9. Coupled flow, thermal and structural analysis of aerodynamically heated panels

    NASA Technical Reports Server (NTRS)

    Thornton, Earl A.; Dechaumphai, Pramote

    1986-01-01

    A finite element approach to coupling flow, thermal and structural analyses of aerodynamically heated panels is presented. The Navier-Stokes equations for laminar compressible flow are solved together with the energy equation and quasi-static structural equations of the panel. Interactions between the flow, panel heat transfer and deformations are studied for thin stainless steel panels aerodynamically heated by Mach 6.6 flow.

  10. Shuttle ascent and shock impingement aerodynamic heating studies

    NASA Technical Reports Server (NTRS)

    Lanning, W. D.; Hung, F. T.

    1971-01-01

    The collection and analysis of aerodynamic heating data obtained from shock impingement experimental investigation were completed. The data were categorized into four interference areas; fin leading edge, wing/fuselage fin/plate corners, and space shuttle configurations. The effects of shock impingement were found to increase the heating rates 10 to 40 times the undisturbed values. A test program was completed at NASA/Langley Research Center to investigate the magnitudes and surface patterns of the mated shock interference flowfield. A 0.0065 scale thin-skin model of the MDAC 256-20 space shuttle booster mated with a Stycast model of the MDAC Internal tank orbiter was tested in the 20-inch M=6 tunnel, the 31-inch M=10 tunnel, and the 48-inch Unitary Plan Tunnel. The gap region of the ascent configuration was the principal area of interest where both thermocouple and phase-change paint data were obtained. Pressure and heat transfer distributions data on the leeward surface of a 75-degree sweep slab delta wing are presented. The effects of surface roughness on boundary layer transition and aerodynamic heating were investigated.

  11. Aerodynamic pressure and heating-rate distributions in tile gaps around chine regions with pressure gradients at a Mach number of 6.6

    NASA Technical Reports Server (NTRS)

    Hunt, L. Roane; Notestine, Kristopher K.

    1990-01-01

    Surface and gap pressures and heating-rate distributions were obtained for simulated Thermal Protection System (TPS) tile arrays on the curved surface test apparatus of the Langley 8-Foot High Temperature Tunnel at Mach 6.6. The results indicated that the chine gap pressures varied inversely with gap width because larger gap widths allowed greater venting from the gap to the lower model side pressures. Lower gap pressures caused greater flow ingress from the surface and increased gap heating. Generally, gap heating was greater in the longitudinal gaps than in the circumferential gaps. Gap heating decreased with increasing gap depth. Circumferential gap heating at the mid-depth was generally less than about 10 percent of the external surface value. Gap heating was most severe at local T-gap junctions and tile-to-tile forward-facing steps that caused the greatest heating from flow impingement. The use of flow stoppers at discrete locations reduced heating from flow impingement. The use of flow stoppers at discrete locations reduced heating in most gaps but increased heating in others. Limited use of flow stoppers or gap filler in longitudinal gaps could reduce gap heating in open circumferential gaps in regions of high surface pressure gradients.

  12. CFD Modeling of Launch Vehicle Aerodynamic Heating

    NASA Technical Reports Server (NTRS)

    Tashakkor, Scott B.; Canabal, Francisco; Mishtawy, Jason E.

    2011-01-01

    The Loci-CHEM 3.2 Computational Fluid Dynamics (CFD) code is being used to predict Ares-I launch vehicle aerodynamic heating. CFD has been used to predict both ascent and stage reentry environments and has been validated against wind tunnel tests and the Ares I-X developmental flight test. Most of the CFD predictions agreed with measurements. On regions where mismatches occurred, the CFD predictions tended to be higher than measured data. These higher predictions usually occurred in complex regions, where the CFD models (mainly turbulence) contain less accurate approximations. In some instances, the errors causing the over-predictions would cause locations downstream to be affected even though the physics were still being modeled properly by CHEM. This is easily seen when comparing to the 103-AH data. In the areas where predictions were low, higher grid resolution often brought the results closer to the data. Other disagreements are attributed to Ares I-X hardware not being present in the grid, as a result of computational resources limitations. The satisfactory predictions from CHEM provide confidence that future designs and predictions from the CFD code will provide an accurate approximation of the correct values for use in design and other applications

  13. Experimental investigation of turbine disk cavity aerodynamics and heat transfer

    NASA Technical Reports Server (NTRS)

    Daniels, W. A.; Johnson, B. V.

    1993-01-01

    An experimental investigation of turbine disk cavity aerodynamics and heat transfer was conducted to provide an experimental data base that can guide the aerodynamic and thermal design of turbine disks and blade attachments for flow conditions and geometries simulating those of the space shuttle main engine (SSME) turbopump drive turbines. Experiments were conducted to define the nature of the aerodynamics and heat transfer of the flow within the disk cavities and blade attachments of a large scale model simulating the SSME turbopump drive turbines. These experiments include flow between the main gas path and the disk cavities, flow within the disk cavities, and leakage flows through the blade attachments and labyrinth seals. Air was used to simulate the combustion products in the gas path. Air and carbon dioxide were used to simulate the coolants injected at three locations in the disk cavities. Trace amounts of carbon dioxide were used to determine the source of the gas at selected locations on the rotors, the cavity walls, and the interstage seal. The measurements on the rotor and stationary walls in the forward and aft cavities showed that the coolant effectiveness was 90 percent or greater when the coolant flow rate was greater than the local free disk entrainment flow rate and when room temperature air was used as both coolant and gas path fluid. When a coolant-to-gas-path density ratio of 1.51 was used in the aft cavity, the coolant effectiveness on the rotor was also 90 percent or greater at the aforementioned condition. However, the coolant concentration on the stationary wall was 60 to 80 percent at the aforementioned condition indicating a more rapid mixing of the coolant and flow through the rotor shank passages. This increased mixing rate was attributed to the destabilizing effects of the adverse density gradients.

  14. Low-perigee aerodynamic heating during orbital flight of an atmosphere Explorer

    NASA Technical Reports Server (NTRS)

    Caruso, P. S., Jr.; Naegeli, C. R.

    1976-01-01

    An extensive, low-perigee orbital aerodynamic heating study was undertaken in support of the Atmosphere Explorer-C Temperature Alarm. State of the art of low-density, high-speed flows, some models of the earth's atmosphere, external flow-field definition, thermodynamic and transport properties of atmospheric gases, the accommodation coefficient orbital thermal environment, and correlation of theory and measurements are discussed. Aerodynamic heating rates are determined for eight selected orbits by means of a reduced, analytical model verified by both ground test and flight data. These heating rates are compared with classical free-molecule and first-order collision regime values.

  15. Aerodynamic Heating and Deceleration During Entry into Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    1962-01-01

    Aerodynamic Heating and Deceleration During Entry into Planetary Atmospheres. Dr. Chapman's lecture examines the physics behind spacecraft entry into planetary atmospheres. He explains how scientists determine if a planet has an atmosphere and how scientists can compute deceleration when the atmospheric conditions are unknown. Symbols and equations used for calculations for aerodynamic heating and deceleration are provided. He also explains heat transfer in bodies approaching an atmosphere, deceleration, and the use of ablation in protecting spacecraft from high temperatures during atmospheric entry. [Entire movie available on DVD from CASI as Doc ID 20070030962. Contact help@sti.nasa.gov

  16. Theoretical and empirical low perigee aerodynamic heating during orbital flight of an atmosphere explorer

    NASA Technical Reports Server (NTRS)

    Caruso, P. S., Jr.; Naegeli, C. R.

    1976-01-01

    This document presents the results of an extensive, low perigee, orbital aerodynamic heating study undertaken in support of the Atmosphere Explorer-C Temperature Alarm. Based upon in-flight orbital temperature data from the Temperature Alarm tungsten resistance wire thermometer, aerodynamic heating rates have been determined for eight selected orbits by means of a reduced thermal analytical model verified by both ground test and flight data. These heating rates are compared with the classical free molecular and first order collision regime values. It has been concluded that, for engineering purposes, the aerodynamic heating rate of atmospheric gases at perigee altitudes between 170 and 135 km on pure tungsten wire is 30 to 60% of the value set by the classical free molecular limit. Relative to the more usual orbital thermal input attributable to direct solar radiation, the aerodynamic heating rate at the lowest altitude attempted with the spacecraft despun (135 km) is the equivalent of about 1.2 solar constants incident on a tungsten wire with a solar absorptivity of 0.85.

  17. Aerodynamics of heat exchangers for high-altitude aircraft

    NASA Technical Reports Server (NTRS)

    Drela, Mark

    1996-01-01

    Reduction of convective beat transfer with altitude dictates unusually large beat exchangers for piston- engined high-altitude aircraft The relatively large aircraft drag fraction associated with cooling at high altitudes makes the efficient design of the entire heat exchanger installation an essential part of the aircraft's aerodynamic design. The parameters that directly influence cooling drag are developed in the context of high-altitude flight Candidate wing airfoils that incorporate heat exchangers are examined. Such integrated wing-airfoil/heat-exchanger installations appear to be attractive alternatives to isolated heat.exchanger installations. Examples are drawn from integrated installations on existing or planned high-altitude aircraft.

  18. Enhancement of the CAVE computer code. [aerodynamic heating package for nose cones and scramjet engine sidewalls

    NASA Technical Reports Server (NTRS)

    Rathjen, K. A.; Burk, H. O.

    1983-01-01

    The computer code CAVE (Conduction Analysis via Eigenvalues) is a convenient and efficient computer code for predicting two dimensional temperature histories within thermal protection systems for hypersonic vehicles. The capabilities of CAVE were enhanced by incorporation of the following features into the code: real gas effects in the aerodynamic heating predictions, geometry and aerodynamic heating package for analyses of cone shaped bodies, input option to change from laminar to turbulent heating predictions on leading edges, modification to account for reduction in adiabatic wall temperature with increase in leading sweep, geometry package for two dimensional scramjet engine sidewall, with an option for heat transfer to external and internal surfaces, print out modification to provide tables of select temperatures for plotting and storage, and modifications to the radiation calculation procedure to eliminate temperature oscillations induced by high heating rates. These new features are described.

  19. A wall grid scale criterion for hypersonic aerodynamic heating calculation

    NASA Astrophysics Data System (ADS)

    Yang, Jianlong; Liu, Meng

    2017-07-01

    The theory of molecular motion was used to study the wall cell Reynolds number method, and it found that the height of the first grid point off wall is related to the molecular mean free path near wall. A wall grid scale criterion based on the molecular mean free path at the stagnation point was proposed by considering both the flow parameters and the wall temperature boundaries. The criterion was verified through numerical calculations and comparative analyses of the wall heat flux in different hypersonic flow fields. Research results draw the following conclusions: The optimal height of the first grid point off wall is a molecular mean free path. The influence of height of the first grid point off wall on aerodynamic heat is much greater than that of aerodynamic force. The criterion is not only effective for the wall heat flux predictions in air conditions, but also useful to that of non air environments. With the weakening of aerodynamic heating along the flow direction, the effect of wall grid scale on the wall heat flux gradually decreases.

  20. Aerodynamic heating and surface temperatures on vehicles for computer-aided design studies

    NASA Technical Reports Server (NTRS)

    Dejarnette, F. R.; Kania, L. A.; Chitty, A.

    1983-01-01

    A computer subprogram has been developed to calculate aerodynamic and radiative heating rates and to determine surface temperatures by integrating the heating rates along the trajectory of a vehicle. Convective heating rates are calculated by applying the axisymmetric analogue to inviscid surface streamlines and using relatively simple techniques to calculate laminar, transitional, or turbulent heating rates. Options are provided for the selection of gas model, transition criterion, turbulent heating method, Reynolds Analogy factor, and entropy-layer swallowing effects. Heating rates are compared to experimental data, and the time history of surface temperatures are given for a high-speed trajectory. The computer subprogram is developed for preliminary design and mission analysis where parametric studies are needed at all speeds.

  1. Aerodynamic heating and surface temperatures on vehicles for computer-aided design studies

    NASA Technical Reports Server (NTRS)

    Dejarnette, F. R.; Kania, L. A.; Chitty, A.

    1983-01-01

    A computer subprogram has been developed to calculate aerodynamic and radiative heating rates and to determine surface temperatures by integrating the heating rates along the trajectory of a vehicle. Convective heating rates are calculated by applying the axisymmetric analogue to inviscid surface streamlines and using relatively simple techniques to calculate laminar, transitional, or turbulent heating rates. Options are provided for the selection of gas model, transition criterion, turbulent heating method, Reynolds Analogy factor, and entropy-layer swallowing effects. Heating rates are compared to experimental data, and the time history of surface temperatures are given for a high-speed trajectory. The computer subprogram is developed for preliminary design and mission analysis where parametric studies are needed at all speeds.

  2. Fluid-thermal-structural study of aerodynamically heated leading edges

    NASA Technical Reports Server (NTRS)

    Deuchamphai, Pramote; Thornton, Earl A.; Wieting, Allan R.

    1988-01-01

    A finite element approach for integrated fluid-thermal-structural analysis of aerodynamically heated leading edges is presented. The Navier-Stokes equations for high speed compressible flow, the energy equation, and the quasi-static equilibrium equations for the leading edge are solved using a single finite element approach in one integrated, vectorized computer program called LIFTS. The fluid-thermal-structural coupling is studied for Mach 6.47 flow over a 3-in diam cylinder for which the flow behavior and the aerothermal loads are calibrated by experimental data. Issues of the thermal-structural response are studied for hydrogen-cooled, super thermal conducting leading edges subjected to intense aerodynamic heating.

  3. A Radiant Heater to Simulate Aerodynamic Heating in a Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Trussell, Donald H.; Weidman, Deene J.

    1960-01-01

    A recently developed radiant-heating test technique for simulation of aerodynamic heating in wind tunnel is describes. The heating device, which utilized quartz-tube lamps, was operated successfully while exposed directly to a supersonic airstream. Tests were made on a calibration panel, and experimental temperature and pressure data are presented. Results indicate that initial heating rates of about 26 Btu/(sq ft) (sec) are obtainable at a distance of 12 inches from the heater. Further applications of the basic design are discussed briefly.

  4. Benchmark aerodynamic heat-transfer data from the first flight of the Space Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Throckmorton, D. A.

    1982-01-01

    Benchmark entry aerodynamic heat-transfer data were determined from the first flight of the Space Shuttle Orbiter. The convective heating-rate data result from a rigorous mathematical analysis of one-dimensional, transient heat conduction within the orbiter thermal protection system (TPS) and reradiation from its surface during entry. Temperatures measured at the TPS surface during orbiter entry provide a constraint to the analysis. On the vehicle leeside, where heating rate levels are low, corrections are made to the computed convective heating rates to account for solar radiation and cross-radiation between fuselage and wing surfaces. The source of the entry thermal data, the mathematical analysis technique, and the TPS thermal models are discussed. Typical convective heating rate data from the STS-1 mission are presented.

  5. Joint influences of aerodynamic flow field and aerodynamic heating of the dome on imaging quality degradation of airborne optical systems.

    PubMed

    Xiao, Haosu; Zuo, Baojun; Tian, Yi; Zhang, Wang; Hao, Chenglong; Liu, Chaofeng; Li, Qi; Li, Fan; Zhang, Li; Fan, Zhigang

    2012-12-20

    We investigated the joint influences exerted by the nonuniform aerodynamic flow field surrounding the optical dome and the aerodynamic heating of the dome on imaging quality degradation of an airborne optical system. The Spalart-Allmaras model provided by FLUENT was used for flow computations. The fourth-order Runge-Kutta algorithm based ray tracing program was used to simulate optical transmission through the aerodynamic flow field and the dome. Four kinds of imaging quality evaluation parameters were presented: wave aberration of the exit pupil, point spread function, encircled energy, and modulation transfer function. The results show that the aero-optical disturbance of the aerodynamic flow field and the aerodynamic heating of the dome significantly affect the imaging quality of an airborne optical system.

  6. A study of the motion and aerodynamic heating of missiles entering the earth's atmosphere at high supersonic speeds

    NASA Technical Reports Server (NTRS)

    Allen, Julian H; Eggers, A J , Jr

    1957-01-01

    A simplified analysis of the velocity and deceleration history of missiles entering the earth's atmosphere at high supersonic speeds is presented. The results of this motion analysis are employed to indicate means available to the designer for minimizing aerodynamic heating. The heating problem considered involves not only the total heat transferred to a missile by convection, but also the maximum average and local time rates of convective heat transfer.

  7. A study of the motion and aerodynamic heating of ballistic missiles entering the earth's atmosphere at high supersonic speeds

    NASA Technical Reports Server (NTRS)

    Allen, H Julian; Eggers, A J , Jr

    1958-01-01

    A simplified analysis of the velocity and deceleration history of ballistic missiles entering the earth's atmosphere at high supersonic speeds is presented. The results of this motion analysis are employed to indicate means available to the designer for minimizing aerodynamic heating. The heating problem considered involves not only the total heat transferred to a missile by convection, but also the maximum average and local time rates of convective heat transfer.

  8. Aerodynamic Heat-Power Engine Operating on a Closed Cycle

    NASA Technical Reports Server (NTRS)

    Ackeret, J.; Keller, D. C.

    1942-01-01

    Hot-air engines with dynamic compressors and turbines offer new prospects of success through utilization of units of high efficiencies and through the employment of modern materials of great strength at high temperature. Particular consideration is given to an aerodynamic prime mover operating on a closed circuit and heated externally. Increase of the pressure level of the circulating air permits a great increase of limit load of the unit. This also affords a possibility of regulation for which the internal efficiency of the unit changes but slightly. The effect of pressure and temperature losses is investigated. A general discussion is given of the experimental installation operating at the Escher Wyss plant in Zurich for a considerable time at high temperatures.

  9. Advanced multistage turbine blade aerodynamics, performance, cooling, and heat transfer

    SciTech Connect

    Fleeter, S.; Lawless, P.B.

    1995-12-31

    The gas turbine has the potential for power production at the highest possible efficiency. The challenge is to ensure that gas turbines operate at the optimum efficiency so as to use the least fuel and produce minimum emissions. A key component to meeting this challenge is the turbine. Turbine performance, both aerodynamics and heat transfer, is one of the barrier advanced gas turbine development technologies. This is a result of the complex, highly three-dimensional and unsteady flow phenomena in the turbine. Improved turbine aerodynamic performance has been achieved with three-dimensional highly-loaded airfoil designs, accomplished utilizing Euler or Navier-Stokes Computational Fluid Dynamics (CFD) codes. These design codes consider steady flow through isolated blade rows. Thus they do not account for unsteady flow effects. However, unsteady flow effects have a significant impact on performance. Also, CFD codes predict the complete flow field. The experimental verification of these codes has traditionally been accomplished with point data - not corresponding plane field measurements. Thus, although advanced CFD predictions of the highly complex and three-dimensional turbine flow fields are available, corresponding data are not. To improve the design capability for high temperature turbines, a detailed understanding of the highly unsteady and three-dimensional flow through multi-stage turbines is necessary. Thus, unique data are required which quantify the unsteady three-dimensional flow through multi-stage turbine blade rows, including the effect of the film coolant flow. Also, as design CFD codes do not account for unsteady flow effects, the next logical challenge and the current thrust in CFD code development is multiple-stage analyses that account for the interactions between neighboring blade rows. Again, to verify and or direct the development of these advanced codes, complete three-dimensional unsteady flow field data are needed.

  10. Advanced multistage turbine blade aerodynamics, performance, cooling, and heat transfer

    SciTech Connect

    Fleeter, S.; Lawless, P.B.

    1995-10-01

    The gas turbine has the potential for power production at the highest possible efficiency. The challenge is to ensure that gas turbines operate at the optimum efficiency so as to use the least fuel and produce minimum emissions. A key component to meeting this challenge is the turbine. Turbine performance, both aerodynamics and heat transfer, is one of the barrier advanced gas turbine development technologies. This is a result of the complex, highly three-dimensional and unsteady flow phenomena in the turbine. Improved turbine aerodynamic performance has been achieved with three-dimensional highly-loaded airfoil designs, accomplished utilizing Euler or Navier-Stokes Computational Fluid Dynamics (CFD) codes. These design codes consider steady flow through isolated blade rows. Thus they do not account for unsteady flow effects. However, unsteady flow effects have a significant impact on performance. Also, CFD codes predict the complete flow field. The experimental verification of these codes has traditionally been accomplished with point data - not corresponding plane field measurements. Thus, although advanced CFD predictions of the highly complex and three-dimensional turbine flow fields are available, corresponding data are not. To improve the design capability for high temperature turbines, a detailed understanding of the highly unsteady and three-dimensional flow through multi-stage turbines is necessary. Thus, unique data are required which quantify the unsteady three-dimensional flow through multi-stage turbine blade rows, including the effect of the film coolant flow. This requires experiments in appropriate research facilities in which complete flow field data, not only point measurements, are obtained and analyzed. Also, as design CFD codes do not account for unsteady flow effects, the next logical challenge and the current thrust in CFD code development is multiple-stage analyses that account for the interactions between neighboring blade rows.

  11. Aerodynamic and base heating studies on space shuttle configurations

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Heating rate and pressure measurements were obtained on a 25-O space shuttle model in a vacuum chamber. Correlation data on windward laminar and turbulent boundary layers and leeside surfaces of the space shuttle orbiter are included.

  12. Numerical Simulation of Aerodynamic Heating Reduction due to Opposing Jet in Supersonic Flow

    NASA Astrophysics Data System (ADS)

    Li, H. Y.; Eri, Q. T.

    In supersonic flight, severe aerodynamic heating takes place at the nose of blunt body and causes ablation. Accurate prediction of aerodynamic heating and construction of proper thermal protection system are required. The numerical study on a reduction of aerodynamic heating by opposing jet has been conducted. Flow field around a hemisphere model is calculated in supersonic free stream of Mach number 3.98 and the coolant gas is injected through the nozzle at the nose the model. CFD method was Finite Volume Method for time integration be used, axisymmetric full Navier-Stokes equations were applied as governing equations and k-ɛturbulence model is used. Numerical simulation demonstrated, compared with no jet, the reduction of aerodynamic heating due to opposing jet was to be proved quite effective at the nose of blunt body. Parameters in this numerical study insofar, as the pressure ratio is increased, caused the wall pressure and heat flux decrease, and recirculation region size largen. effective reduction of the aerodynamic heating remarkably. As the opposing nozzle diameter ratio was decreased, the pressure and heat flux increased, and recirculation region size lessening, the effect of reduction aerodynamic heating was reduced.

  13. An engineering aerodynamic heating method for hypersonic flow

    NASA Technical Reports Server (NTRS)

    Riley, Christopher J.; Dejarnette, Fred R.

    1992-01-01

    A capability to calculate surface heating rates has been incorporated in an approximate three-dimensional inviscid technique. Surface streamlines are calculated from the inviscid solution, and the axisymmetric analog is then used along with a set of approximate convective-heating equations to compute the surface heat transfer. The method is applied to blunted axisymmetric and three-dimensional ellipsoidal cones at angle of attack for the laminar flow of a perfect gas. The method is also applicable to turbulent and equilibrium-air conditions. The present technique predicts surface heating rates that compare favorably with experimental (ground-test and flight) data and numerical solutions of the Navier-Stokes (NS) and viscous shock-layer (VSL) equations. The new technique represents a significant improvement over current engineering aerothermal methods with only a modest increase in computational effort.

  14. An Engineering Aerodynamic Heating Method for Hypersonic Flow

    NASA Technical Reports Server (NTRS)

    Riley, Christopher J.; DeJarnette, Fred R.

    1992-01-01

    A capability to calculate surface heating rates has been incorporated in an approximate three-dimensional inviscid technique. Surface streamlines are calculated from the inviscid solution, and the axisymmetric analog is then used along with a set of approximate convective-heating equations to compute the surface heat transfer. The method is applied to blunted axisymmetric and three-dimensional ellipsoidal cones at angle of attack for the laminar flow of a perfect gas. The method is also applicable to turbulent and equilibrium-air conditions. The present technique predicts surface heating rates that compare favorably with experimental (ground-test and flight) data and numerical solutions of the Navier-Stokes (NS) and viscous shock-layer (VSL) equations. The new technique represents a significant improvement over current engineering aerothermal methods with only a modest increase in computational effort.

  15. An engineering aerodynamic heating method for hypersonic flow

    NASA Technical Reports Server (NTRS)

    Riley, Christopher J.; Dejarnette, Fred R.

    1992-01-01

    A capability to calculate surface heating rates has been incorporated in an approximate three-dimensional inviscid technique. Surface streamlines are calculated from the inviscid solution, and the axisymmetric analog is then used along with a set of approximate convective-heating equations to compute the surface heat transfer. The method is applied to blunted axisymmetric and three-dimensional ellipsoidal cones at angle of attack for the laminar flow of a perfect gas. The method is also applicable to turbulent and equilibrium-air conditions. The present technique predicts surface heating rates that compare favorably with experimental (ground-test and flight) data and numerical solutions of the Navier-Stokes (NS) and viscous shock-layer (VSL) equations. The new technique represents a significant improvement over current engineering aerothermal methods with only a modest increase in computational effort.

  16. A study of aerodynamic heating distributions on a tip-fin controller installed on a Space Shuttle Orbiter model

    NASA Technical Reports Server (NTRS)

    Wittliff, C. E.

    1982-01-01

    The aerodynamic heating of a tip-fin controller mounted on a Space Shuttle Orbiter model was studied experimentally in the Calspan Advanced Technology Center 96 inch Hypersonic Shock Tunnel. A 0.0175 scale model was tested at Mach numbers from 10 to 17.5 at angles of attack typical of a shuttle entry. The study was conducted in two phases. In phase 1 testing a thermographic phosphor technique was used to qualitatively determine the areas of high heat-transfer rates. Based on the results of this phase, the model was instrumented with 40 thin-film resistance thermometers to obtain quantitative measurements of the aerodynamic heating. The results of the phase 2 testing indicate that the highest heating rates, which occur on the leading edge of the tip-fin controller, are very sensitive to angle of attack for alpha or = 30 deg. The shock wave from the leading edge of the orbiter wing impinges on the leading edge of the tip-fin controller resulting in peak values of h/h(Ref) in the range from 1.5 to 2.0. Away from the leading edge, the heat-transfer rates never exceed h/h(Ref) = 0.25 when the control surface, is not deflected. With the control surface deflected 20 deg, the heat-transfer rates had a maximum value of h/h(Ref) = 0.3. The heating rates are quite nonuniform over the outboard surface and are sensitive to angle of attack.

  17. Modeling of aerodynamic heat flux and thermoelastic behavior of nose caps of hypersonic vehicles

    NASA Astrophysics Data System (ADS)

    Persova, Marina G.; Soloveichik, Yury G.; Belov, Vasiliy K.; Kiselev, Dmitry S.; Vagin, Denis V.; Domnikov, Petr A.; Patrushev, Ilya I.; Kurskiy, Denis N.

    2017-07-01

    In this paper, the problem of numerical modeling of thermoelastic behavior of nose caps of hypersonic vehicles at different angles of attack is considered. 3D finite element modeling is performed by solving the coupled heat and elastic problems taking into account thermal and mechanical properties variations with temperature. A special method for calculating the aerodynamic heat flux entering the nose cap from its surface is proposed. This method is characterized by very low computational costs and allows calculating the aerodynamic heat flux at different values of the Mach number and angles of attack which may vary during the aerodynamic heating. The numerical results obtained by the proposed approach are compared with the numerical results and experimental data obtained by other authors. The developed approach has been used for studying the impact of the angle of attack on the thermoelastic behavior of nose caps main components.

  18. Enthalpy By Energy Balance for Aerodynamic Heating Facility at NASA Ames Research Center Arc Jet Complex

    NASA Technical Reports Server (NTRS)

    Hightower, T. Mark; MacDonald, Christine L.; Martinez, Edward R.; Balboni, John A.; Anderson, Karl F.; Arnold, Jim O. (Technical Monitor)

    2002-01-01

    The NASA Ames Research Center (ARC) Arc Jet Facilities' Aerodynamic Heating Facility (AHF) has been instrumented for the Enthalpy By Energy Balance (EB2) method. Diagnostic EB2 data is routinely taken for all AHF runs. This paper provides an overview of the EB2 method implemented in the AHF. The chief advantage of the AHF implementation over earlier versions is the non-intrusiveness of the instruments used. For example, to measure the change in cooling water temperature, thin film 1000 ohm Resistance Temperature Detectors (RTDs) are used with an Anderson Current Loop (ACL) as the signal conditioner. The ACL with 1000 ohm RTDs allows for very sensitive measurement of the increase in temperature (Delta T) of the cooling water to the arc heater, which is a critical element of the EB2 method. Cooling water flow rates are measured with non-intrusive ultrasonic flow meters.

  19. Aerodynamic heating to representative SRB and ET protuberances

    NASA Technical Reports Server (NTRS)

    Engel, C. D.; Lapointe, J. K.

    1979-01-01

    Heating data and data scaling methods which can be used on representative solid rocket booster and external tank (ET) protuberances are described. Topics covered include (1) ET geometry and heating points; (2) interference heating test data (51A); (3) heat transfer data from tests FH-15 and FH-16; (4) individual protuberance data; and (5) interference heating of paint data from test IH-42. A set of drawings of the ET moldline and protuberances is included.

  20. SRB ascent aerodynamic heating design criteria reduction study, volume 1

    NASA Technical Reports Server (NTRS)

    Crain, W. K.; Frost, C. L.; Engel, C. D.

    1989-01-01

    An independent set of solid rocket booster (SRB) convective ascent design environments were produced which would serve as a check on the Rockwell IVBC-3 environments used to design the ascent phase of flight. In addition, support was provided for lowering the design environments such that Thermal Protection System (TPS), based on conservative estimates, could be removed leading to a reduction in SRB refurbishment time and cost. Ascent convective heating rates and loads were generated at locations in the SRB where lowering the thermal environment would impact the TPS design. The ascent thermal environments are documented along with the wind tunnel/flight test data base used as well as the trajectory and environment generation methodology. Methodology, as well as, environment summaries compared to the 1980 Design and Rockwell IVBC-3 Design Environment are presented in this volume, 1.

  1. Thermal Analysis and Design of Multi-layer Insulation for Re-entry Aerodynamic Heating

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran

    2001-01-01

    The combined radiation/conduction heat transfer in high-temperature multi-layer insulations was modeled using a finite volume numerical model. The numerical model was validated by comparison with steady-state effective thermal conductivity measurements, and by transient thermal tests simulating re-entry aerodynamic heating conditions. A design of experiments technique was used to investigate optimum design of multi-layer insulations for re-entry aerodynamic heating. It was found that use of 2 mm foil spacing and locating the foils near the hot boundary with the top foil 2 mm away from the hot boundary resulted in the most effective insulation design. A 76.2 mm thick multi-layer insulation using 1, 4, or 16 foils resulted in 2.9, 7.2, or 22.2 percent mass per unit area savings compared to a fibrous insulation sample at the same thickness, respectively.

  2. SRB ascent aerodynamic heating design criteria reduction study, volume 2

    NASA Technical Reports Server (NTRS)

    Crain, W. K.; Frost, C. L.; Engel, C. D.

    1989-01-01

    Data are presented for the wind tunnel interference heating factor data base, the timewise tabulated ascent design environments, and the timewise plotted environments comparing the REMTECH results to the Rockwell RI-IVBC-3 results.

  3. Advanced turbine cooling, heat transfer, and aerodynamic studies

    SciTech Connect

    Han, Je-Chin; Schobeiri, M.T.

    1995-12-31

    The contractual work is in three parts: Part I - Effect of rotation on enhanced cooling passage heat transfer, Part II - Effect of Thermal Barrier Coating (TBC) spallation on surface heat transfer, and Part III - Effect of surface roughness and trailing edge ejection on turbine efficiency under unsteady flow conditions. Each section of this paper has been divided into three parts to individually accommodate each part. Part III is further divided into Parts IIIa and IIIb.

  4. Advanced turbine cooling, heat transfer, and aerodynamic studies

    SciTech Connect

    Je-Chin Han; Schobeiri, M.T.

    1995-10-01

    The contractual work is in three parts: Part I - Effect of rotation on enhanced cooling passage heat transfer, Part II - Effect on Thermal Barrier Coating (TBC) spallation on surface heat transfer, and Part III - Effect of surface roughness and trailing edge ejection on turbine efficiency under unsteady flow conditions. Each section of this paper has been divided into three parts to individually accommodate each part. Part III is further divided into Parts IIIa and IIIb.

  5. Turbulence Modeling and Computation of Turbine Aerodynamics and Heat Transfer

    NASA Technical Reports Server (NTRS)

    Lakshminarayana, B.; Luo, J.

    1996-01-01

    The objective of the present research is to develop improved turbulence models for the computation of complex flows through turbomachinery passages, including the effects of streamline curvature, heat transfer and secondary flows. Advanced turbulence models are crucial for accurate prediction of rocket engine flows, due to existance of very large extra strain rates, such as strong streamline curvature. Numerical simulation of the turbulent flows in strongly curved ducts, including two 180-deg ducts, one 90-deg duct and a strongly concave curved turbulent boundary layer have been carried out with Reynolds stress models (RSM) and algebraic Reynolds stress models (ARSM). An improved near-wall pressure-strain correlation has been developed for capturing the anisotropy of turbulence in the concave region. A comparative study of two modes of transition in gas turbine, the by-pass transition and the separation-induced transition, has been carried out with several representative low-Reynolds number (LRN) k-epsilon models. Effects of blade surface pressure gradient, freestream turbulence and Reynolds number on the blade boundary layer development, and particularly the inception of transition are examined in detail. The present study indicates that the turbine blade transition, in the presence of high freestream turbulence, is predicted well with LRN k-epsilon models employed. The three-dimensional Navier-Stokes procedure developed by the present authors has been used to compute the three-dimensional viscous flow through the turbine nozzle passage of a single stage turbine. A low Reynolds number k-epsilon model and a zonal k-epsilon/ARSM (algebraic Reynolds stress model) are utilized for turbulence closure. An assessment of the performance of the turbulence models has been carried out. The two models are found to provide similar predictions for the mean flow parameters, although slight improvement in the prediction of some secondary flow quantities has been obtained by the

  6. Influence of Aerodynamic Strain Rate on Local Extinction in Turbulent Non-premixed Jet Flames

    NASA Astrophysics Data System (ADS)

    Ramachandran, Aravind; Narayanaswamy, Venkateswaran; Lyons, Kevin

    2016-11-01

    2-D velocity field measurements obtained from Particle Image Velocimetry (PIV) are used to obtain aerodynamic strain rate information in regions of local extinction in lifted turbulent non-premixed methane jet flames in coflow. Diluting the coflow to reduce the oxygen molefraction results in increased occurrences of local extinction. Statistical analysis is performed to correlate regions of high local strain rate with local extinctions in both air coflow and diluted coflow cases to study the influence of strain rate against vortical structures in extinguishing the flame front. A comparison is also made with heated and vitiated coflow cases, where autoignition is a flame stabilization mechanism and influenced by local strain rate. At high jet exit velocities (Ux > > Ur), the out-of-plane strain rate component can be neglected but the convection of extinguished pockets into the measurement plane needs to be resolved by stereoscopic (3-D) measurements which will be done in a future work. This work has been supported by the U.S. Army Research Office (Contracts W911NF1210140 and W911NF1610087) Dr. Ralph Anthenien, Technical Monitor, ARO.

  7. Sensible heat flux of oil palm plantation: Comparing Aerodynamic and Penman-Monteith Methods

    NASA Astrophysics Data System (ADS)

    Amri Komarudin, Nurul; June, Tania; Meijide, Ana

    2017-01-01

    Oil Palm (Elaeis guinensis Jacq) has a unique morphological characteristics, in particular it has a uniform canopy. As the plant become older, its canopy coverage will completely cover the surface and influence characteristics of its microclimate. Sensible heat flux estimation of oil palm plantation could be used to identify the contribution of oil palm in reducing or increasing heat to its surrounding environment. Determination of heat flux from oil palm plantation was conducted using two methods, Aerodynamic and Penman-Monteith. The result shows that the two methods have similar diurnal pattern. The sensible heat flux peaks in the afternoon, both for two and twelve years oil palm plantations. Sensible heat flux of young plantation is affected by atmospheric stability (stable, unstable and neutral), and is higher than that of older plantation, with mean values of 0.52 W/m2 (stable), 43.53 W/m2 (unstable), 0.63 W/m2 (neutral), with standard deviation of 0.50, 28.75 and 0.46 respectively. Sensible heat flux estimated by Penman-Monteith method in both young and older plantation was higher than the value determined by Aerodynamic method with respective value of 0.77 W/m2 (stable), 45.13 W/m2 (unstable) and 0.63 W/m2 (neutral) and 0.34 W/m2 (stable), 35.82 W/m2 (unstable) and 0.71 W/m2 (neutral).

  8. Assessment of predictive capabilities for aerodynamic heating in hypersonic flow

    NASA Astrophysics Data System (ADS)

    Knight, Doyle; Chazot, Olivier; Austin, Joanna; Badr, Mohammad Ali; Candler, Graham; Celik, Bayram; Rosa, Donato de; Donelli, Raffaele; Komives, Jeffrey; Lani, Andrea; Levin, Deborah; Nompelis, Ioannis; Panesi, Marco; Pezzella, Giuseppe; Reimann, Bodo; Tumuklu, Ozgur; Yuceil, Kemal

    2017-04-01

    The capability for CFD prediction of hypersonic shock wave laminar boundary layer interaction was assessed for a double wedge model at Mach 7.1 in air and nitrogen at 2.1 MJ/kg and 8 MJ/kg. Simulations were performed by seven research organizations encompassing both Navier-Stokes and Direct Simulation Monte Carlo (DSMC) methods as part of the NATO STO AVT Task Group 205 activity. Comparison of the CFD simulations with experimental heat transfer and schlieren visualization suggest the need for accurate modeling of the tunnel startup process in short-duration hypersonic test facilities, and the importance of fully 3-D simulations of nominally 2-D (i.e., non-axisymmmetric) experimental geometries.

  9. Comparison of Various Supersonic Turbine Tip Designs to Minimize Aerodynamic Loss and Tip Heating

    NASA Technical Reports Server (NTRS)

    Shyam, Vikram; Ameri, Ali

    2012-01-01

    The rotor tips of axial turbines experience high heat flux and are the cause of aerodynamic losses due to tip clearance flows, and in the case of supersonic tips, shocks. As stage loadings increase, the flow in the tip gap approaches and exceeds sonic conditions. This introduces effects such as shock-boundary layer interactions and choked flow that are not observed for subsonic tip flows that have been studied extensively in literature. This work simulates the tip clearance flow for a flat tip, a diverging tip gap and several contoured tips to assess the possibility of minimizing tip heat flux while maintaining a constant massflow from the pressure side to the suction side of the rotor, through the tip clearance. The Computational Fluid Dynamics (CFD) code GlennHT was used for the simulations. Due to the strong favorable pressure gradients the simulations assumed laminar conditions in the tip gap. The nominal tip gap width to height ratio for this study is 6.0. The Reynolds number of the flow is 2.4 x 10(exp 5) based on nominal tip width and exit velocity. A wavy wall design was found to reduce heat flux by 5 percent but suffered from an additional 6 percent in aerodynamic loss coefficient. Conventional tip recesses are found to perform far worse than a flat tip due to severe shock heating. Overall, the baseline flat tip was the second best performer. A diverging converging tip gap with a hole was found to be the best choice. Average tip heat flux was reduced by 37 percent and aerodynamic losses were cut by over 6 percent.

  10. The variation of heat transfer coefficient, adiabatic effectiveness and aerodynamic loss with film cooling hole shape.

    PubMed

    Sargison, J E; Guo, S M; Oldfield, M L; Rawlinson, A J

    2001-05-01

    The heat transfer coefficient and adiabatic effectiveness of cylindrical, fan shaped holes and a slot are presented for the region zero to 50 diameters downstream of the holes. Narrow-band liquid crystals were used on a heated flat plate with heated air coolant. These parameters have been measured in a steady state, low speed facility at engine representative Reynolds number based on hole diameter and pressure difference ratio (ideal momentum flux ratio). The aerodynamic loss due to each of the film cooling geometries has been measured using a traverse of the boundary layer far downstream of the film cooling holes. Compared to the cylindrical holes, the fan shaped hole case showed an improvement in the uniformity of cooling downstream of the holes and in the level of laterally averaged film cooling effectiveness. The fan effectiveness approached the slot level and both the fan and cylindrical hole cases show lower heat transfer coefficients than the slot and non film cooled cases based on the laterally averaged results. The drawback to the fan shaped hole was that the aerodynamic loss was significantly higher than both the slot and cylindrical hole values due to inefficient diffusion in the hole exit expansion.

  11. Modeling and Simulation of Radiative Compressible Flows in Aerodynamic Heating Arc-Jet Facility

    NASA Technical Reports Server (NTRS)

    Bensassi, Khalil; Laguna, Alejandro A.; Lani, Andrea; Mansour, Nagi N.

    2016-01-01

    Numerical simulations of an arc heated flow inside NASA's 20 [MW] Aerodynamics heating facility (AHF) are performed in order to investigate the three-dimensional swirling flow and the current distribution inside the wind tunnel. The plasma is considered in Local Thermodynamics Equilibrium(LTE) and is composed of Air-Argon gas mixture. The governing equations are the Navier-Stokes equations that include source terms corresponding to Joule heating and radiative cooling. The former is obtained by solving an electric potential equation, while the latter is calculated using an innovative massively parallel ray-tracing algorithm. The fully coupled system is closed by the thermodynamics relations and transport properties which are obtained from Chapman-Enskog method. A novel strategy was developed in order to enable the flow solver and the radiation calculation to be preformed independently and simultaneously using a different number of processors. Drastic reduction in the computational cost was achieved using this strategy. Details on the numerical methods used for space discretization, time integration and ray-tracing algorithm will be presented. The effect of the radiative cooling on the dynamics of the flow will be investigated. The complete set of equations were implemented within the COOLFluiD Framework. Fig. 1 shows the geometry of the Anode and part of the constrictor of the Aerodynamics heating facility (AHF). Fig. 2 shows the velocity field distribution along (x-y) plane and the streamline in (z-y) plane.

  12. A method of infrared imaging missile's aerodynamic heating modeling and simulations

    NASA Astrophysics Data System (ADS)

    Cao, Chunqin; Xiang, Jingbo; Zhang, Xiaoyang; Wang, Weiqiang

    2013-09-01

    The infrared (IR) imaging missile's dome will be heated when fly at high speed in the atmosphere because of the friction of the air flow blocking. The detector's performance will be decline if the dome surface is heated to a certain temperature. In this paper, we find a right way to evaluate the aerothermal effects in the imaging and information processing algorithm. Which have three steps including the aerothermal radiation calculation, quantization and image reconstruction. Firstly, the aerothermal radiation is calculated by using a combination of both methods of theoretical analysis and experiment data. Secondly, the relationship between aerothermal radiation and IR images background mean gray and noise can be calculated through the analysis of the experiment data. At last, we can rebuild an aerodynamic heating effect of infrared images fusion with target and decoy, which can be used for virtual prototyping platform missile trajectory simulation. It can be found that the above constructed images have good agreements with the actual image according to comparison between the simulation data and experiment data. It is an economic method that can solve the lab aerodynamic heating simulation and modeling problems.

  13. DSMC method on aerodynamic heating and temperature characteristic of hypersonic rarefied flows

    NASA Astrophysics Data System (ADS)

    Ma, Jing; Bao, Xingdong; Mao, Hongxia; Dong, Yanbing

    2016-10-01

    Aerodynamic heating is one of important factors affecting hypersonic aircraft design. The Direct Simulation Monte Carlo method (DSMC) has evolved years into a powerful numerical technique for the computation of complex, non-equilibrium gas flows. In atmospheric target, non-equilibrium conditions occur at high altitude and in regions of flow fields with small length scales. In this paper, the theoretical basis of the DSMC technique is discussed. In addition, the methods used in DSMC are described for simulation of high temperature, real gas effects and gas-surface interactions. Combined with the solution of heat transfer in material, heat-flux distribution and temperature distribution of the different shape structures was calculated in rarefied conditions.

  14. A dynamic aerodynamic resistance approach to calculate high resolution sensible heat fluxes in urban areas

    NASA Astrophysics Data System (ADS)

    Crawford, Ben; Grimmond, Sue; Kent, Christoph; Gabey, Andrew; Ward, Helen; Sun, Ting; Morrison, William

    2017-04-01

    Remotely sensed data from satellites have potential to enable high-resolution, automated calculation of urban surface energy balance terms and inform decisions about urban adaptations to environmental change. However, aerodynamic resistance methods to estimate sensible heat flux (QH) in cities using satellite-derived observations of surface temperature are difficult in part due to spatial and temporal variability of the thermal aerodynamic resistance term (rah). In this work, we extend an empirical function to estimate rah using observational data from several cities with a broad range of surface vegetation land cover properties. We then use this function to calculate spatially and temporally variable rah in London based on high-resolution (100 m) land cover datasets and in situ meteorological observations. In order to calculate high-resolution QH based on satellite-observed land surface temperatures, we also develop and employ novel methods to i) apply source area-weighted averaging of surface and meteorological variables across the study spatial domain, ii) calculate spatially variable, high-resolution meteorological variables (wind speed, friction velocity, and Obukhov length), iii) incorporate spatially interpolated urban air temperatures from a distributed sensor network, and iv) apply a modified Monte Carlo approach to assess uncertainties with our results, methods, and input variables. Modeled QH using the aerodynamic resistance method is then compared to in situ observations in central London from a unique network of scintillometers and eddy-covariance measurements.

  15. Estimating monthly-averaged air-sea transfers of heat and momentum using the bulk aerodynamic method

    NASA Technical Reports Server (NTRS)

    Esbensen, S. K.; Reynolds, R. W.

    1980-01-01

    Air-sea transfers of sensible heat, latent heat, and momentum are computed from twenty-five years of middle-latitude and subtropical ocean weather ship data in the North Atlantic and North Pacific using the bulk aerodynamic method. The results show that monthly-averaged wind speeds, temperatures, and humidities can be used to estimate the monthly-averaged sensible and latent heat fluxes computed from the bulk aerodynamic equations to within a relative error of approximately 10%. The estimate of monthly-averaged wind stress under the assumption of neutral stability are shown to be within approximately 5% of the monthly-averaged non-neutral values.

  16. The Effect of Aerodynamic Heating on Air Penetration by Shaped Charge Jets and Their Particles

    NASA Astrophysics Data System (ADS)

    Backofen, Joseph

    2009-06-01

    The goal of this paper is to present recent work modeling thermal coupling between shaped charge jets and their particles with air while it is being penetrated to form a crater that subsequently collapses back onto the jet. This work complements research published at International Symposia on Ballistics: 1) 1987 - Shaped Charge Jet Aerodynamics, Particulation and Blast Field Modeling; and 2) 2007 - Air Cratering by Eroding Shaped Charge Jets. The current work shows how and when a shaped charge jet's tip and jet particles are softened enough that they can erode in a hydrodynamic manner as modeled in these papers. This paper and its presentation includes models for heat transfer from shocked air as a function of jet velocity as well as heat flow within the jet or particle. The work is supported by an extensive bibliographic search including publications on meteors and ballistic missile re-entry vehicles. The modeling shows that a jet loses its strength to the depth required to justify hydrodynamic erosion when its velocity is above a specific velocity related to the shock properties of air and the jet material's properties. As a result, the portion of a jet's kinetic energy converted at the aerodynamic shock into heating transferred back onto the jet affects the energy deposited into the air through drag and ablation which in turn affect air crater expansion and subsequent collapse back onto the jet and its particles as shown in high-speed photography.

  17. Aerodynamic heating on the corrugated surface of a 10.2 deg half-angle blunted cone at Mach 6.7

    NASA Technical Reports Server (NTRS)

    Weinstein, I.; Avery, D. E.; Hunt, L. R.

    1981-01-01

    A 10.2 deg half-angle blunted cone with corrugated surfaces was tested in the Langley 8-foot high-temperature structures tunnel to measure the aerodynamic heating of its surfaces. The tests were made in a turbulent boundary layer at angles of attack of 0 deg, 5 deg, and 10 deg. Heating of the windward side was in reasonable agreement with theoretical turbulent predictions for a smooth cone, while heating on the leeward side was between laminar and turbulent predictions as a result of local transitional flow or flow separation produced by high lee-side pressures. Localized heating measurements indicated a significant increase in heating at large cross-flow angles, with the maximum heating rates occurring where the flow reattaches on the upstream side of the corrugation crest and the minimum occurring on the downstream side where the flow is separated.

  18. Real-time aerodynamic heating and surface temperature calculations for hypersonic flight simulation

    NASA Technical Reports Server (NTRS)

    Quinn, Robert D.; Gong, Leslie

    1990-01-01

    A real-time heating algorithm was derived and installed on the Ames Research Center Dryden Flight Research Facility real-time flight simulator. This program can calculate two- and three-dimensional stagnation point surface heating rates and surface temperatures. The two-dimensional calculations can be made with or without leading-edge sweep. In addition, upper and lower surface heating rates and surface temperatures for flat plates, wedges, and cones can be calculated. Laminar or turbulent heating can be calculated, with boundary-layer transition made a function of free-stream Reynolds number and free-stream Mach number. Real-time heating rates and surface temperatures calculated for a generic hypersonic vehicle are presented and compared with more exact values computed by a batch aeroheating program. As these comparisons show, the heating algorithm used on the flight simulator calculates surface heating rates and temperatures well within the accuracy required to evaluate flight profiles for acceptable heating trajectories.

  19. Aerodynamics, heat and mass transfer in steam-aerosol turbulent flows in containment

    SciTech Connect

    Nigmatulin, B.I.; Pershukov, V.A.; Ris, V.V.

    1995-09-01

    In this report an analysis of aerodynamic and heat transfer processes at the blowdown of gas-dispersed mixture into the containment volume is presented. A few models for description of the volume averaged and local characteristics are analyzed. The mathematical model for description of the local characteristics of the turbulent gas-dispersed flows was developed. The calculation of aerodynamic, heat and mass transfer characteristics was based on the Navier-Stokes, energy and gas mass fractions conservation equations. For calculation of dynamics and deposition of the aerosols the original diffusion-inertia model is developed. The pulsating characteristics of the gaseous phase were calculated on the base (k-{xi}) model of turbulence with modification to account thermogravitational force action and influence of particle mass loading. The appropriate boundary conditions using the {open_quotes}near-wall function{close_quotes} approach was obtained. Testing of the mathematical models and boundary conditions has shown a good agreement between computation and data of comparison. The described mathematical models were applied to two- and three dimensional calculations of the turbulent flow in containment at the various stages of the accident.

  20. Aerodynamic and heat transfer aspects of tip and casing treatments used for turbine tip leakage control

    NASA Astrophysics Data System (ADS)

    Gumusel, Baris

    Axial flow turbine stages are usually designed with a gap between the tips of the rotating blades and a stationary outer casing. The presence of a strong pressure gradient across this gap drives flow from the pressure side of the blade to the suction side. This leakage flow creates a significant amount of energy loss of working fluid in the turbine stage. In a modern gas turbine engine the outer casing of the high-pressure turbine is also exposed to a combination of high flow temperatures and heat transfer coefficients. The casing is consequently subjected to high levels of convective heat transfer, a situation that is aggravated by flow unsteadiness caused by periodic blade-passing events. An experimental investigation of the aerodynamic and heat transfer effect of tip and casing treatments used in turbine tip leakage control was conducted in a large scale, low speed, rotating research turbine facility. The effects of casing treatments were investigated by measuring the total pressure field at the exit of the rotor using a high frequency response total pressure probe. A smooth wall as a baseline case was also investigated. The test cases presented include results of casing treatments with varying dimensions for tip gap height of t/h=2.5%. The results of the rotor exit total pressure indicate that the casing treatment significantly reduced the leakage mass flow rate and the momentum deficit in the core of the tip vortex. The reductions obtained in the tip vortex size and strength influenced the tip-side passage vortex and other typical core flow characteristics in the passage. Casing treatments with the highest ridge height was the most effective in reducing the total pressure loss in the leakage flow of the test blades. This was observed at a radius near the core of the tip vortex. It appears that casing treatments with the highest ridge height is also the most effective from a global point of view, as shown by the passage averaged pressure coefficient obtained in

  1. On the formation of meteoritic chondrules by aerodynamic drag heating in the solar nebula

    NASA Technical Reports Server (NTRS)

    Wood, J. A.

    1984-01-01

    During the formation of the solar nebula, interstellar grains were falling into the nebula with velocities of the order of 10 km/s at the radial distance where the meteorites were to form. This kinetic energy is 20 times the amount of thermal energy needed to melt the grains. The grains were decelerated by aerodynamic drag in the nebula. Where grain-rich parcels of interstellar material fell into the nebula, heat generated by drag could not be radiated away because of the opacity imparted to the system by the grains, and high temperatures were reached. In this situation presolar aggregations of grains would melt to form chondrules. Many of the properties of chondrules (and also Ca/Al-rich inclusions) are consistent with their formation by this means. The infall-heating concept provides a new framework in which the formation and significance of chondritic meteorites can be understood.

  2. A method for calculating aerodynamic heating on sounding rocket tangent ogive noses.

    NASA Technical Reports Server (NTRS)

    Wing, L. D.

    1973-01-01

    A method is presented for calculating the aerodynamic heating and shear stresses at the wall for tangent ogive noses that are slender enough to maintain an attached nose shock through that portion of flight during which heat transfer from the boundary layer to the wall is significant. The lower entropy of the attached nose shock combined with the inclusion of the streamwise pressure gradient yields a reasonable estimate of the actual flow conditions. Both laminar and turbulent boundary layers are examined and an approximation of the effects of (up to) moderate angles-of-attack is included in the analysis. The analytical method has been programmed in FORTRAN IV for an IBM 360/91 computer.

  3. A method for calculating aerodynamic heating on sounding rocket tangent ogive noses

    NASA Technical Reports Server (NTRS)

    Wing, L. D.

    1972-01-01

    A method is presented for calculating the aerodynamic heating and shear stresses at the wall for tangent ogive noses that are slender enough to maintain an attached nose shock through that portion of flight during which heat transfer from the boundary layer to the wall is significant. The lower entropy of the attached nose shock combined with the inclusion of the streamwise pressure gradient yields a reasonable estimate of the actual flow conditions. Both laminar and turbulent boundary layers are examined and an approximation of the effects of (up to) moderate angles-of-attack is included in the analysis. The analytical method has been programmed in FORTRAN 4 for an IBM 360/91 computer.

  4. Convective heat transfer and experimental icing aerodynamics of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Wang, Xin

    The total worldwide base of installed wind energy peak capacity reached 94 GW by the end of 2007, including 1846 MW in Canada. Wind turbine systems are being installed throughout Canada and often in mountains and cold weather regions, due to their high wind energy potential. Harsh cold weather climates, involving turbulence, gusts, icing and lightning strikes in these regions, affect wind turbine performance. Ice accretion and irregular shedding during turbine operation lead to load imbalances, often causing the turbine to shut off. They create excessive turbine vibration and may change the natural frequency of blades as well as promote higher fatigue loads and increase the bending moment of blades. Icing also affects the tower structure by increasing stresses, due to increased loads from ice accretion. This can lead to structural failures, especially when coupled to strong wind loads. Icing also affects the reliability of anemometers, thereby leading to inaccurate wind speed measurements and resulting in resource estimation errors. Icing issues can directly impact personnel safety, due to falling and projected ice. It is therefore important to expand research on wind turbines operating in cold climate areas. This study presents an experimental investigation including three important fundamental aspects: (1) heat transfer characteristics of the airfoil with and without liquid water content (LWC) at varying angles of attack; (2) energy losses of wind energy while a wind turbine is operating under icing conditions; and (3) aerodynamic characteristics of an airfoil during a simulated icing event. A turbine scale model with curved 3-D blades and a DC generator is tested in a large refrigerated wind tunnel, where ice formation is simulated by spraying water droplets. A NACA 63421 airfoil is used to study the characteristics of aerodynamics and convective heat transfer. The current, voltage, rotation of the DC generator and temperature distribution along the airfoil

  5. Thermal stress analysis of space shuttle orbiter subjected to reentry aerodynamic heating

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Fields, Roger A.

    1987-01-01

    A structural performance and resizing (SPAR) finite-element computer program and NASA structural analysis (NASTRAN) finite-element computer programs were used in the thermal stress analysis of the space shuttle orbiter subjected to reentry aerodynamic heating. A SPAR structural model was set up for the entire left wing of the orbiter, and NASTRAN structural models were set up for: (1) a wing segment located at midspan of the orbiter left wing, and (2) a fuselage segment located at midfuselage. The thermal stress distributions in the orbiter structure were obtained and the critical high thermal stress regions were identified. It was found that the thermal stresses induced in the orbiter structure during reentry were relatively low. The thermal stress predictions from the whole wing model were considered to be more accurate than those from the wing segment model because the former accounts for temperature and stress effects throughout the entire wing.

  6. Aerodynamic and heat transfer analysis of the low aspect ratio turbine

    NASA Astrophysics Data System (ADS)

    Sharma, O. P.; Nguyen, P.; Ni, R. H.; Rhie, C. M.; White, J. A.

    1987-06-01

    The available two- and three-dimensional codes are used to estimate external heat loads and aerodynamic characteristics of a highly loaded turbine stage in order to demonstrate state-of-the-art methodologies in turbine design. By using data for a low aspect ratio turbine, it is found that a three-dimensional multistage Euler code gives good averall predictions for the turbine stage, yielding good estimates of the stage pressure ratio, mass flow, and exit gas angles. The nozzle vane loading distribution is well predicted by both the three-dimensional multistage Euler and three-dimensional Navier-Stokes codes. The vane airfoil surface Stanton number distributions, however, are underpredicted by both two- and three-dimensional boundary value analysis.

  7. Non-equilibrium stagnation region aerodynamic heating of hypersonic glide vehicles

    NASA Technical Reports Server (NTRS)

    Rosner, D. E.; Cibrian, R.

    1974-01-01

    A simple method of predicting aerodynamic heating and corresponding radiation equilibrium surface temperature-time histories for critical locations on space shuttle orbiter-type vehicles is presented. The method is based on a generalization of correlation equations developed earlier by Rosner for predicting the energy transfer and radiation equilibrium temperatures of surfaces with arbitrary catalytic activity and total hemispheric emittance. Recently obtained experimental data for O and N atom recombination probabilities on candidate material surfaces above 1000 K are used to assess nonequilibrium effects for a range of nose radii and a specific space shuttle re-entry trajectory. It is concluded that low catalytic activity will be especially important in locations of large effective nose radii by both increasing oxidation-resistant coating lifetime and reducing energy transfer into the vehicle.

  8. Effects of aerodynamic heating and TPS thermal performance uncertainties on the Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Goodrich, W. D.; Derry, S. M.; Maraia, R. J.

    1980-01-01

    A procedure for estimating uncertainties in the aerodynamic-heating and thermal protection system (TPS) thermal-performance methodologies developed for the Shuttle Orbiter is presented. This procedure is used in predicting uncertainty bands around expected or nominal TPS thermal responses for the Orbiter during entry. Individual flowfield and TPS parameters that make major contributions to these uncertainty bands are identified and, by statistical considerations, combined in a manner suitable for making engineering estimates of the TPS thermal confidence intervals and temperature margins relative to design limits. Thus, for a fixed TPS design, entry trajectories for future Orbiter missions can be shaped subject to both the thermal-margin and confidence-interval requirements. This procedure is illustrated by assessing the thermal margins offered by selected areas of the existing Orbiter TPS design for an entry trajectory typifying early flight test missions.

  9. Non-equilibrium stagnation region aerodynamic heating of hypersonic glide vehicles

    NASA Technical Reports Server (NTRS)

    Rosner, D. E.; Cibrian, R.

    1974-01-01

    A simple method of predicting aerodynamic heating and corresponding radiation equilibrium surface temperature-time histories for critical locations on space shuttle orbiter-type vehicles is presented. The method is based on a generalization of correlation equations developed earlier by Rosner for predicting the energy transfer and radiation equilibrium temperatures of surfaces with arbitrary catalytic activity and total hemispheric emittance. Recently obtained experimental data for O and N atom recombination probabilities on candidate material surfaces above 1000 K are used to assess nonequilibrium effects for a range of nose radii and a specific space shuttle re-entry trajectory. It is concluded that low catalytic activity will be especially important in locations of large effective nose radii by both increasing oxidation-resistant coating lifetime and reducing energy transfer into the vehicle.

  10. Static and dynamic aeroelastic characterization of an aerodynamically heated generic hypersonic aircraft configuration

    NASA Technical Reports Server (NTRS)

    Heeg, Jennifer; Gilbert, Michael G.; Pototzky, Anthony S.

    1990-01-01

    This work-in-progress presentation describes an ongoing research activity at the NASA Langley Research Center to develop analytical methods for the prediction of aerothermoelastic stability of hypersonic aircraft including active control systems. The objectives of this research include application of aerothermal loads to the structural finite element model, determination of the thermal effects on flutter, and assessment of active controls technology applied to overcome any potential adverse aeroelastic stability or response problems due to aerodynamic heating- namely flutter suppression and ride quality improvement. For this study, a generic hypersonic aircraft configuration was selected which incorporates wing flaps, ailerons and all-moveable fins to be used for active control purposes. The active control systems would use onboard sensors in a feedback loop through the aircraft flight control computers to move the surfaces for improved structural dynamic response as the aircraft encounters atmospheric turbulence.

  11. Motion of a ballistic missile angularly misaligned with the flight path upon entering the atmosphere and its effect upon aerodynamic heating, aerodynamic loads, and miss distance

    NASA Technical Reports Server (NTRS)

    Allen, Julian H

    1957-01-01

    An analysis is given of the oscillating motion of a ballistic missile which upon entering the atmosphere is angularly misaligned with respect to the flight path. The history of the motion for some example missiles is discussed from the point of view of the effect of the motion on the aerodynamic heating and loading. The miss distance at the target due to misalignment and to small accidental trim angles is treated. The stability problem is also discussed for the case where the missile is tumbling prior to atmospheric entry.

  12. Comparative study on aerodynamic heating under perfect and nonequilibrium hypersonic flows

    NASA Astrophysics Data System (ADS)

    Wang, Qiu; Li, JinPing; Zhao, Wei; Jiang, ZongLin

    2016-02-01

    In this study, comparative heat flux measurements for a sharp cone model were conducted by utilizing a high enthalpy shock tunnel JF-10 and a large-scale shock tunnel JF-12, responsible for providing nonequilibrium and perfect gas flows, respectively. Experiments were performed at the Key Laboratory of High Temperature Gas Dynamics (LHD), Institute of Mechanics, Chinese Academy of Sciences. Corresponding numerical simulations were also conducted in effort to better understand the phenomena accompanying in these experiments. By assessing the consistency and accuracy of all the data gathered during this study, a detailed comparison of sharp cone heat transfer under a totally different kind of freestream conditions was build and analyzed. One specific parameter, defined as the product of the Stanton number and the square root of the Reynold number, was found to be more characteristic for the aerodynamic heating phenomena encountered in hypersonic flight. Adequate use of said parameter practically eliminates the variability caused by the deferent flow conditions, regardless of whether the flow is in dissociation or the boundary condition is catalytic. Essentially, the parameter identified in this study reduces the amount of ground experimental data necessary and eases data extrapolation to flight.

  13. Heat exchangers: Selection, rating, and thermal design

    SciTech Connect

    Kakac, S.; Liu, H.

    1998-01-01

    This book takes a systematic approach to the subject, focusing on the selection, design, rating, and operational challenges of various types of heat exchangers. Written by well-known authors in the field of heat transfer, this book covers all the most commonly used types of heat exchangers, including condensers and evaporators. The text begins with the classification of the different types of heat exchangers and discusses methods for their sizing and rating. Single phase forced convection correlations in ducts and pressure drop and pumping power analysis are also covered. A chapter is devoted to the special problem of fouling. Thermal design methods and processes, including designs for condensers and evaporators, complete this thorough introduction to the subject. The appendix provides information on the thermophysical properties of fluids, including the new refrigerants. Every topic features worked examples to illustrate the methods and procedures presented, and additional problems are included at the end of each chapter, with examples to be used as a student design project. An instructor's manual is available, including complete solutions to selected problems in the text. The contents include: classification of heat exchangers; basic design methods of heat exchangers; forced convection correlations for single-phase side of heat exchangers; heat exchanger pressure drop and pumping power; fouling of heat exchangers; double-pipe heat exchangers; design correlations for condensers and evaporators; shell-and-tube heat exchangers; compact heat exchangers; gasketed-plate heat exchangers; and condensers and evaporators.

  14. Thermal electron heating rate: A derivation

    NASA Technical Reports Server (NTRS)

    Hoegy, W. R.

    1983-01-01

    The thermal electron heating rate is an important heat source term in the ionospheric electron energy balance equation, representing heating by photoelectrons or by precipitating higher energy electrons. A formula for the thermal electron heating rate is derived from the kinetic equation using the electron-electron collision operator as given by the unified theory of Kihara and Aono. This collision operator includes collective interactions to produce a finite collision operator with an exact Coulomb logarithm term. The derived heating rate O(e) is the sum of three terms, O(e) = O(p) + S + O(int), which are respectively: (1) primary electron production term giving the heating from newly created electrons that have not yet suffered collisions with the ambient electrons; (2) a heating term evaluated on the energy surface m(e)/2 = E(T) at the transition between Maxwellian and tail electrons at E(T); and (3) the integral term representing heating of Maxwellian electrons by energetic tail electrons at energies ET. Published ionospheric electron temperature studies used only the integral term O(int) with differing lower integration limits. Use of the incomplete heating rate could lead to erroneous conclusions regarding electron heat balance, since O(e) is greater than O(int) by as much as a factor of two.

  15. LOVEL: a low-velocity aerodynamic heating code for flat-plates, wedges, and cones

    SciTech Connect

    Thornton, A.L.

    1981-12-01

    The LOVEL computer program calculates the boundary-layer edge conditions for subsonic and supersonic flow over flat-plate, wedge, and cone geometries for freestream Mach conditions (M/sub infinity/ < 3. Cold-wall heat-transfer calculations use reference temperature correlations based on boundary-layer edge Mach number to compute fluid properties. The first part of this report describes the theory used in the computation of the cold-wall heat-transfer rates; the second part describes in detail the input/output format for the LOVEL computer program. Outputs include freestream conditions, boundary-layer edge conditions, cold-wall heat-transfer rates, plots of heating rates, and punched-card output for use in ablation and in-depth transient heat-conduction computer codes.

  16. Pressure distribution and aerodynamic coefficients associated with heat addition to supersonic air stream adjacent to two-dimensional supersonic wing

    NASA Technical Reports Server (NTRS)

    Pinkel, I Irving; Serafini, John S; Gregg, John L

    1952-01-01

    The modifications in the pressure distributions and the aerodynamic coefficients associated with additions of heat to the two-dimensional supersonic in viscid flow field adjacetnt to the lower surface of of a 5-percent-thickness symmetrical circular-arc wing are presented in this report. The pressure distributions are obtained by the use of graphical method which gives the two-dimensional supersonic inviscid flow field obtained with moderate heat addition. The variation is given of the lift-drag ratio and of the aerodynamic coefficients of lift, drag, and moment with free stream Mach number, angle of attack, and parameters defining extent and amount of heat addition. The six graphical solutions used in this study included Mach numbers of 3.0 and 5.0 and angles of attack of 0 degrees and 2 degrees.

  17. Fluid-thermal analysis of aerodynamic heating over spiked blunt body configurations

    NASA Astrophysics Data System (ADS)

    Qin, Qihao; Xu, Jinglei; Guo, Shuai

    2017-03-01

    When flying at hypersonic speeds, the spiked blunt body is constantly subjected to severe aerodynamic heating. To illustrate the thermal response of different configurations and the relevant flow field variation, a loosely-coupled fluid-thermal analysis is performed in this paper. The Mesh-based parallel Code Coupling Interface (MpCCI) is adopted to implement the data exchange between the fluid solver and the thermal solver. The results indicate that increases in spike diameter and length will result in a sharp decline of the wall temperature along the spike, and the overall heat flux is remarkably reduced to less than 300 W/cm2 with the aerodome mounted at the spike tip. Moreover, the presence and evolution of small vortices within the recirculation zone are observed and proved to be induced by the stagnation effect of reattachment points on the spike. In addition, the drag coefficient of the configuration with a doubled spike length presents a maximum drop of 4.59% due to the elevated wall temperature. And the growing difference of the drag coefficient is further increased during the accelerating process.

  18. Aerodynamic heating environment definition/thermal protection system selection for the HL-20

    NASA Astrophysics Data System (ADS)

    Wurster, K. E.; Stone, H. W.

    1993-09-01

    Definition of the aerothermal environment is critical to any vehicle such as the HL-20 Personnel Launch System that operates within the hypersonic flight regime. Selection of an appropriate thermal protection system design is highly dependent on the accuracy of the heating-environment prediction. It is demonstrated that the entry environment determines the thermal protection system design for this vehicle. The methods used to predict the thermal environment for the HL-20 Personnel Launch System vehicle are described. Comparisons of the engineering solutions with computational fluid dynamic predictions, as well as wind-tunnel test results, show good agreement. The aeroheating predictions over several critical regions of the vehicle, including the stagnation areas of the nose and leading edges, windward centerline and wing surfaces, and leeward surfaces, are discussed. Results of predictions based on the engineering methods found within the MINIVER aerodynamic heating code are used in conjunction with the results of the extensive wind-tunnel tests on this configuration to define a flight thermal environment. Finally, the selection of the thermal protection system based on these predictions and current technology is described.

  19. Aerodynamic heating environment definition/thermal protection system selection for the HL-20

    NASA Technical Reports Server (NTRS)

    Wurster, K. E.; Stone, H. W.

    1993-01-01

    Definition of the aerothermal environment is critical to any vehicle such as the HL-20 Personnel Launch System that operates within the hypersonic flight regime. Selection of an appropriate thermal protection system design is highly dependent on the accuracy of the heating-environment prediction. It is demonstrated that the entry environment determines the thermal protection system design for this vehicle. The methods used to predict the thermal environment for the HL-20 Personnel Launch System vehicle are described. Comparisons of the engineering solutions with computational fluid dynamic predictions, as well as wind-tunnel test results, show good agreement. The aeroheating predictions over several critical regions of the vehicle, including the stagnation areas of the nose and leading edges, windward centerline and wing surfaces, and leeward surfaces, are discussed. Results of predictions based on the engineering methods found within the MINIVER aerodynamic heating code are used in conjunction with the results of the extensive wind-tunnel tests on this configuration to define a flight thermal environment. Finally, the selection of the thermal protection system based on these predictions and current technology is described.

  20. An environmental rating for heat pump equipment

    NASA Astrophysics Data System (ADS)

    Hughes, P. J.

    1992-10-01

    The major federal and state regulatory trends that may affect heat pump markets are reviewed. Then the confluence of federal and state regulation, and what it may mean for heat pump markets, is discussed. The conclusion reached, and therefore the assumption for the rest of the paper, is that state regulators will increasingly be managing the environmental impacts associated with alternative heating, cooling, and water heating methods within the framework of Integrated Resource Planning (IRP). The input needs of IRP are reviewed, and some shortcomings of existing rating procedures for providing the IRP inputs are identified. Finally, the paper concludes with a brief suggestion on course of action.

  1. Radiative heating rates during AAOE and AASE

    NASA Astrophysics Data System (ADS)

    Rosenfield, Joan E.

    Radiative transit computations of heating rates utilizing data from the 1987 Airborne Antarctic Ozone Experiment (AAOE) (Tuck et al., 1989) and the 1989 Airborne Arctic Stratospheric Experiment (AASE) (Turco et al., 1990) are described. Observed temperature and ozone profiles and a radiative transfer model are used to compute the heating rates for the Southern Hemisphere during AAOE and the Northern Hemisphere during AASE. The AASE average cooling rates computed inside the vortex are in good agreement with the diabatic cooling rates estimated from the ER-2 profile data for N2O for the AASE period (Schoeberl et al., 1989).

  2. Structure of Ba-Ti-Al-O glasses produced by aerodynamic levitation and laser heating

    NASA Astrophysics Data System (ADS)

    Kidkhunthod, Pinit; Skinner, Lawrie B.; Barnes, Adrian C.; Klysubun, Wantana; Fischer, Henry E.

    2014-09-01

    Ba0.09Al0.18Ti0.12O0.61 glasses have been produced by aerodynamic levitation and laser heating. Neutron diffraction, x-ray diffraction, x-ray absorption spectroscopy, molecular dynamics simulation, and reverse Monte Carlo refinement methods have been used to obtain a detailed atomistic structural model of the glass. This model has been used to investigate its atomic coordination and network structure. It is found that the Al atoms are almost exclusively fourfold tetrahedrally coordinated to oxygen atoms. In contrast, the Ti atoms coordinate to oxygen atoms in approximately equal numbers of four- and fivefold coordinated sites with a small number of sixfold sites. The results show the presence of some tetrahedral TiO4 structural motifs although the dominant O-Ti-O bond angle occurs at 90∘ . It is found that Al/Ti-O network structure shows strong similarities with other oxide glass forming systems although a first sharp diffraction peak is not observed. The results are used to discuss the unusual properties of the Ba-Al-Ti-O glasses produced under different quenching conditions.

  3. Enhancements to the high speed convective heating and viscous drag prediction techniques of the Aerodynamic Preliminary Analysis System (APAS)

    NASA Technical Reports Server (NTRS)

    Cruz, Christopher I.; Engelund, Walter C.

    1991-01-01

    APAS is an interactive computer program that allows a user to quickly estimate the aerodynamic characteristics of aerospace and aeronautical vehicles throughout the speed range using a single geometry definition. This report documents the major differences between the high speed analysis portion of the APAS and the Mark III version of the hypersonic arbitrary-body program from which it has evolved and compares convective heating and viscous drag results from the APAS with CFD results, experimental data, and flight data.

  4. Aerodynamics of road vehicles

    SciTech Connect

    Hucho, W.H.

    1987-01-01

    This introduction to aerodynamic aspects of motor vehicle design will be of use both to vehicle designers and students of automobile engineering. Content covers vehicle systems, ventilation and aerodynamic design to reduce drag and increase stability of cars, commercial vehicles and PSVs. Topics considered include automobile aerodynamics; some fundamentals of fluid mechanics; performance of cars and light vans; aerodynamic drag of passenger cars; driving stability in sidewinds; operation, safety and comfort; high-performance vehicle aerodynamics; commercial vehicles; engine cooling systems; heating, ventilation and air conditioning of motor vehicles; wind tunnels for automobile aerodynamics; measuring and testing techniques; and numerical methods for computation of flow around road vehicles.

  5. Maximum orbit plane change with heat-transfer-rate considerations

    NASA Technical Reports Server (NTRS)

    Lee, J. Y.; Hull, D. G.

    1990-01-01

    Two aerodynamic maneuvers are considered for maximizing the plane change of a circular orbit: gliding flight with a maximum thrust segment to regain lost energy (aeroglide) and constant altitude cruise with the thrust being used to cancel the drag and maintain a high energy level (aerocruise). In both cases, the stagnation heating rate is limited. For aeroglide, the controls are the angle of attack, the bank angle, the time at which the burn begins, and the length of the burn. For aerocruise, the maneuver is divided into three segments: descent, cruise, and ascent. During descent the thrust is zero, and the controls are the angle of attack and the bank angle. During cruise, the only control is the assumed-constant angle of attack. During ascent, a maximum thrust segment is used to restore lost energy, and the controls are the angle of attack and bank angle. The optimization problems are solved with a nonlinear programming code known as GRG2. Numerical results for the Maneuverable Re-entry Research Vehicle with a heating-rate limit of 100 Btu/ft(2)-s show that aerocruise gives a maximum plane change of 2 deg, which is only 1 deg larger than that of aeroglide. On the other hand, even though aerocruise requires two thrust levels, the cruise characteristics of constant altitude, velocity, thrust, and angle of attack are easy to control.

  6. Aerodynamic Analysis of Simulated Heat Shield Recession for the Orion Command Module

    NASA Technical Reports Server (NTRS)

    Bibb, Karen L.; Alter, Stephen J.; Mcdaniel, Ryan D.

    2008-01-01

    The aerodynamic effects of the recession of the ablative thermal protection system for the Orion Command Module of the Crew Exploration Vehicle are important for the vehicle guidance. At the present time, the aerodynamic effects of recession being handled within the Orion aerodynamic database indirectly with an additional safety factor placed on the uncertainty bounds. This study is an initial attempt to quantify the effects for a particular set of recessed geometry shapes, in order to provide more rigorous analysis for managing recession effects within the aerodynamic database. The aerodynamic forces and moments for the baseline and recessed geometries were computed at several trajectory points using multiple CFD codes, both viscous and inviscid. The resulting aerodynamics for the baseline and recessed geometries were compared. The forces (lift, drag) show negligible differences between baseline and recessed geometries. Generally, the moments show a difference between baseline and recessed geometries that correlates with the maximum amount of recession of the geometry. The difference between the pitching moments for the baseline and recessed geometries increases as Mach number decreases (and the recession is greater), and reach a value of -0.0026 for the lowest Mach number. The change in trim angle of attack increases from approx. 0.5deg at M = 28.7 to approx. 1.3deg at M = 6, and is consistent with a previous analysis with a lower fidelity engineering tool. This correlation of the present results with the engineering tool results supports the continued use of the engineering tool for future work. The present analysis suggests there does not need to be an uncertainty due to recession in the Orion aerodynamic database for the force quantities. The magnitude of the change in pitching moment due to recession is large enough to warrant inclusion in the aerodynamic database. An increment in the uncertainty for pitching moment could be calculated from these results and

  7. Research on Streamlines and Aerodynamic Heating for Unstructured Grids on High-Speed Vehicles

    NASA Technical Reports Server (NTRS)

    DeJarnette, Fred R.; Hamilton, H. Harris (Technical Monitor)

    2001-01-01

    Engineering codes are needed which can calculate convective heating rates accurately and expeditiously on the surfaces of high-speed vehicles. One code which has proven to meet these needs is the Langley Approximate Three-Dimensional Convective Heating (LATCH) code. It uses the axisymmetric analogue in an integral boundary-layer method to calculate laminar and turbulent heating rates along inviscid surface streamlines. It requires the solution of the inviscid flow field to provide the surface properties needed to calculate the streamlines and streamline metrics. The LATCH code has been used with inviscid codes which calculated the flow field on structured grids, Several more recent inviscid codes calculate flow field properties on unstructured grids. The present research develops a method to calculate inviscid surface streamlines, the streamline metrics, and heating rates using the properties calculated from inviscid flow fields on unstructured grids. Mr. Chris Riley, prior to his departure from NASA LaRC, developed a preliminary code in the C language, called "UNLATCH", to accomplish these goals. No publication was made on his research. The present research extends and improves on the code developed by Riley. Particular attention is devoted to the stagnation region, and the method is intended for programming in the FORTRAN 90 language.

  8. Experimental Study of Vane Heat Transfer and Aerodynamics at Elevated Levels of Turbulence

    NASA Technical Reports Server (NTRS)

    Ames, Forrest E.

    1994-01-01

    A four vane subsonic cascade was used to investigate how free stream turbulence influences pressure surface heat transfer. A simulated combustor turbulence generator was built to generate high level (13 percent) large scale (Lu approximately 44 percent inlet span) turbulence. The mock combustor was also moved upstream to generate a moderate level (8.3 percent) of turbulence for comparison to smaller scale grid generated turbulence (7.8 percent). The high level combustor turbulence caused an average pressure surface heat transfer augmentation of 56 percent above the low turbulence baseline. The smaller scale grid turbulence produced the next greatest effect on heat transfer and demonstrated the importance of scale on heat transfer augmentation. In general, the heat transfer scaling parameter U(sub infinity) TU(sub infinity) LU(sub infinity)(exp -1/3) was found to hold for the turbulence. Heat transfer augmentation was also found to scale approximately on Re(sub ex)(exp 1/3) at constant turbulence conditions. Some evidence of turbulence intensification in terms of elevated dissipation rates was found along the pressure surface outside the boundary layer. However, based on the level of dissipation and the resulting heat transfer augmentation, the amplification of turbulence has only a moderate effect on pressure surface heat transfer. The flow field turbulence does drive turbulent production within the boundary layer which in turn causes the high levels of heat transfer augmentation. Unlike heat transfer, the flow field straining was found to have a significant effect on turbulence isotropy. On examination of the one dimensional spectra for u' and v', the effect to isotropy was largely limited to lower wavenumber spectra. The higher wavenumber spectra showed little or no change. The high level large scale turbulence was found to have a strong influence on wake development. The free stream turbulence significantly enhanced mixing resulting in broader and shallower

  9. Program documentation: Surface heating rate of thin skin models (THNSKN)

    NASA Technical Reports Server (NTRS)

    Mcbryde, J. D.

    1975-01-01

    Program THNSKN computes the mean heating rate at a maximum of 100 locations on the surface of thin skin transient heating rate models. Output is printed in tabular form and consists of time history tabulation of temperatures, average temperatures, heat loss without conduction correction, mean heating rate, least squares heating rate, and the percent standard error of the least squares heating rates. The input tape used is produced by the program EHTS03.

  10. Aerodynamic heating on AFE due to nonequilibrium flow with variable entropy at boundary layer edge

    NASA Technical Reports Server (NTRS)

    Ting, P. C.; Rochelle, W. C.; Bouslog, S. A.; Tam, L. T.; Scott, C. D.; Curry, D. M.

    1991-01-01

    A method of predicting the aerobrake aerothermodynamic environment on the NASA Aeroassist Flight Experiment (AFE) vehicle is described. Results of a three dimensional inviscid nonequilibrium solution are used as input to an axisymmetric nonequilibrium boundary layer program to predict AFE convective heating rates. Inviscid flow field properties are obtained from the Euler option of the Viscous Reacting Flow (VRFLO) code at the boundary layer edge. Heating rates on the AFE surface are generated with the Boundary Layer Integral Matrix Procedure (BLIMP) code for a partially catalytic surface composed of Reusable Surface Insulation (RSI) times. The 1864 kg AFE will fly an aerobraking trajectory, simulating return from geosynchronous Earth orbit, with a 75 km perigee and a 10 km/sec entry velocity. Results of this analysis will provide principal investigators and thermal analysts with aeroheating environments to perform experiment and thermal protection system design.

  11. Novel behaviour and structure of new glasses of the type Ba-Al-O and Ba-Al-Ti-O produced by aerodynamic levitation and laser heating.

    PubMed

    Skinner, L B; Barnes, A C; Crichton, W

    2006-08-16

    Novel barium aluminate (BaAl(2)O(4)) and barium alumino-titanate (BaAl(2)TiO(6)) glasses have been produced by aerodynamic levitation and laser heating. BaAl(2)O(4) forms a clear and colourless glass under containerless and rapid quenching conditions. Under similar rapid quenching conditions BaAl(2)TiO(6) forms an opaque and black glass, while under slower and controlled quenching conditions it is possible to form a clear and colourless glass. The formation of the opaque or clear glass is reversible and purely dependent on the quench rate used. By slowing the quench rate further, it is possible to produce a milky glass suggestive of liquid-liquid phase separation in the liquid before glassification. High-energy x-ray diffraction experiments confirm the glassy state of these materials and show coordination structures and bond distances similar to their crystalline analogues.

  12. Radiative heating rates near the stratospheric fountain

    NASA Technical Reports Server (NTRS)

    Doherty, G. M.; Newell, R. E.; Danielsen, E. F.

    1984-01-01

    Radiative heating rates are computed for various sets of conditions thought to be appropriate to the stratospheric fountain region: with and without a layer of cirrus cloud between 100 and 150 mbar; with standard ozone and with decreased ozone in the lower stratosphere, again with and without the cirrus cloud; and with different temperatures in the tropopause region. The presence of the cloud decreases the radiative cooling below the cloud in the upper troposphere and increases the cooling above it in the lower stratosphere. The cloud is heated at the base and cooled at the top and thus radiatively destabilized; overall it gains energy by radiation. Decreasing ozone above the cloud also tends to cool the lower stratosphere. The net effect is a tendency for vertical convergence and horizontal divergence in the cloud region. High resolution profiles of temperature, ozone, and cloudiness within the fountain region are required in order to assess the final balance of the various processes.

  13. Effects of Cross-Sectional Shape, Solidity, and Distribution of Heat-Transfer Coefficient on the Torsional Stiffness of Thin Wings Subjected to Aerodynamic Heating

    NASA Technical Reports Server (NTRS)

    Thomson, Robert G.

    1959-01-01

    A study has been made of the effects of varying the shape, solidity, and heat-transfer coefficient of thin wings with regard to their influence on the torsional-stiffness reduction induced by aerodynamic heating. The variations in airfoil shape include blunting, flattening, and combined blunting and flattening of a solid wing of symmetrical double-wedge cross section. Hollow double-wedge wings of constant skin thickness with and without internal webs also are considered. The effects of heat-transfer coefficients appropriate for laminar and turbulent flow are investigated in addition to a step transition along the chord from a lower to a higher constant value of heat-transfer coefficient. From the results given it is concluded that the flattening of a solid double wedge decreases the reduction in torsional stiffness while slight degrees of blunting increase the loss. The influence of chordwise variations in heat-transfer coefficient due to turbulent and laminar boundary-layer flow on the torsional stiffness of solid wings is negligible. The effect of a step transition in heat-transfer coefficient along the chord of a solid wing can, however, become appreciable. The torsional-stiffness reduction of multiweb and hollow double-wedge wings is substantially less than that calculated for a solid wing subjected to the same heating conditions.

  14. Experimental Study of Convective Heating on the Back Face and Payload of a Hypersonic Inflatable Aerodynamic Decelerator (HIAD) Aeroshell

    NASA Technical Reports Server (NTRS)

    Hollis, Brian R.; Berry, Scott A.; Hollingsworth, Kevin E.; Wright, Sheila A.

    2017-01-01

    A wind tunnel test program has been conducted to define convective heating environments on the back-face of a Hypersonic Inflatable Aerodynamic Decelerator aeroshell. Wind tunnel testing was conducted at Mach 6 and Mach 10 at unit Reynolds numbers from 0.5×10(exp 6)/ft to 3.9×10(exp 6)/ft on a 6.3088 in diameter aeroshell model. Global heating data were obtained through phosphor thermography on the aeroshell back face, as well as on the payload and the aeroshell front face. For all test conditions, laminar flow was produced on the aeroshell front face, while the separated wake shear layer and aeroshell back-face boundary layer were transitional or turbulent. Along the leeward centerline of the aeroshell back face and payload centerbody, heating levels increased with both free stream Reynolds number and angle of attack. The Reynolds number dependency was due to increasing strength of wake turbulence with Reynolds number. The angle-of-attack dependency was due to movement of the wake-vortex reattachment point on the aeroshell back face. The maximum heating levels on the aeroshell back face and payload were approximately 5% to 6%, respectively, of the aeroshell front-face stagnation point. To allow for extrapolation of the ground test data to flight conditions, the back face and payload heating levels were correlated as a function of aeroshell front-face peak momentum thickness Reynolds numbers.

  15. Oxidation rates of some heat resistant alloys

    SciTech Connect

    Kelly, J.C.; Wilson, J.D.

    1995-12-31

    Cyclic oxidation testing of several heat resistant alloys was carried out at 1,093 and 1,149 C for times up to 3,000 hours. The quantitative results, coupled with extensive service history for the established alloys, provide a useful guide to anticipated performance of newly developed grades. Maximum practical use temperature is to some extent a function of section size, thin sheet being more quickly depleted of elements used to form the protective scale. Metallurgical factors influencing oxidation rate include grain size as well as the alloying elements silicon, manganese, molybdenum and columbium. Some comparisons are made between laboratory results and service performance.

  16. Experimental Study Of ExoMars Sub-And Transonic Aerodynamics And Heat Shield Separation In HST

    NASA Astrophysics Data System (ADS)

    Neeb, D.; Guilhan, A.; Augenstein, E.

    2011-05-01

    In the framework of the ESA ExoMars project an experimental investigation has been conducted in the transonic DNW wind tunnel HST with two emphases. First the static aerodynamic behaviour of the complete descent module has been investigated in the sub- to transonic flow regime, duplicating reference flight trajectory conditions through the Martian atmosphere. Therefore force and moment coefficients have been derived by means of a six component internal balance with additional pressure signals to enable base pressure corrections. The second main objective was the aerodynamic characterization of the staging process between the capsule’s heat shield and its back cover at corresponding trajectory flight conditions. For this attempt models were available for the capsule’s single parts after separation, e.g. heat shield and back cover. These components have been investigated individually to characterize its behaviour after completion of the separation process as well as to gain reference data to compare to the behaviour during the actual staging process. This flight phase has been simulated in detail by thoroughly modifying the orientation of the separating models to each other. This was enabled by a modular distance between the separating components and modification of the angle of attack. Beside force and moment measurements on the heat shield, the back cover has been equipped with 12 static as well as 12 dynamic pressure sensors. This paper gives an overview of selected results gathered during this test campaign. The measured coefficients for the complete descent module as well as for the separating models are analyzed comparing typical capsule configuration behaviour. Depending on the distance between the separating models clear interferences are evident in both force and pressure signals.

  17. Strain measurement of objects subjected to aerodynamic heating using digital image correlation: Experimental design and preliminary results

    NASA Astrophysics Data System (ADS)

    Pan, Bing; Jiang, Tianyun; Wu, Dafang

    2014-11-01

    In thermomechanical testing of hypersonic materials and structures, direct observation and quantitative strain measurement of the front surface of a test specimen directly exposed to severe aerodynamic heating has been considered as a very challenging task. In this work, a novel quartz infrared heating device with an observation window is designed to reproduce the transient thermal environment experienced by hypersonic vehicles. The specially designed experimental system allows the capture of test article's surface images at various temperatures using an optical system outfitted with a bandpass filter. The captured images are post-processed by digital image correlation to extract full-field thermal deformation. To verify the viability and accuracy of the established system, thermal strains of a chromiumnickel austenite stainless steel sample heated from room temperature up to 600 °C were determined. The preliminary results indicate that the air disturbance between the camera and the specimen due to heat haze induces apparent distortions in the recorded images and large errors in the measured strains, but the average values of the measured strains are accurate enough. Limitations and further improvements of the proposed technique are discussed.

  18. Strain measurement of objects subjected to aerodynamic heating using digital image correlation: experimental design and preliminary results.

    PubMed

    Pan, Bing; Jiang, Tianyun; Wu, Dafang

    2014-11-01

    In thermomechanical testing of hypersonic materials and structures, direct observation and quantitative strain measurement of the front surface of a test specimen directly exposed to severe aerodynamic heating has been considered as a very challenging task. In this work, a novel quartz infrared heating device with an observation window is designed to reproduce the transient thermal environment experienced by hypersonic vehicles. The specially designed experimental system allows the capture of test article's surface images at various temperatures using an optical system outfitted with a bandpass filter. The captured images are post-processed by digital image correlation to extract full-field thermal deformation. To verify the viability and accuracy of the established system, thermal strains of a chromiumnickel austenite stainless steel sample heated from room temperature up to 600 °C were determined. The preliminary results indicate that the air disturbance between the camera and the specimen due to heat haze induces apparent distortions in the recorded images and large errors in the measured strains, but the average values of the measured strains are accurate enough. Limitations and further improvements of the proposed technique are discussed.

  19. Aerodynamic heat transfer to a hypersonic research aircraft model /X-24C/ at Mach 6

    NASA Technical Reports Server (NTRS)

    Lawing, P. L.; Hunt, J. L.

    1976-01-01

    The paper reports on results of heat-transfer tests conducted on a 1/29-scale model of the X-24C-12I hypersonic research aircraft configuration in a Mach 6 tunnel at a Reynolds number of thirteen million using the phase-change heat transfer technique. Sequences of phase-change heat transfer pattern photographs are presented showing windward side and leeward side heating processes. Theoretical predictions of dimensionless heat transfer coefficients along a data line on lower fuselage and on fuselage side bracket the experimental values. A turbulent heating theory gives good agreement with data when shifted to a new virtual origin.

  20. Aerodynamic heat transfer to RSI tile surfaces and gap intersections. [Reusable Surface Insulation

    NASA Technical Reports Server (NTRS)

    Dunavant, J. C.; Throckmorton, D. A.

    1974-01-01

    Review of the results of aerothermal heating tests of a simulated reusable surface insulation (RSI) tile array, performed on the sidewall of a Mach-10 hypersonic tunnel. In particular, the heating characteristics of the tile array, such as they result from heating inside the tile-expansion-space providing gaps between individual tiles, are investigated. The results include the finding that heating on the upstream face of a tile is strongly affected by the interacting longitudinal gap flow.

  1. Aerodynamic Heating Computations for Projectiles. Volume 1. In-Depth Heat Conduction Modifications to the ABRES Shape Change Code (BRLASCC)

    DTIC Science & Technology

    1984-06-01

    Modifications .............................. 16 2.2.2 Explicit Grid Modifications .............................. 19 2.3 Latent Heat of Fusion ...equations are utilized more accurately The user may now input latent heat of fusion for melting materials and BRLASCC will account for this energy during...contact resistance to the finite-difference conduction equations, (3) improved in-depth modeling by inclusion of latent heat of fusion , (4) increased

  2. High Reynolds number and turbulence effects on aerodynamics and heat transfer in a turbine cascade

    NASA Technical Reports Server (NTRS)

    Yeh, Frederick C.; Hippensteele, Steven A.; Vanfossen, G. James; Poinsatte, Philip E.; Ameri, Ali

    1993-01-01

    Experimental data on pressure distribution and heat transfer on a turbine airfoil were obtained over a range of Reynolds numbers from 0.75 to 7.5 x 10 exp 6 and a range of turbulence intensities from 1.8 to about 15 percent. The purpose of this study was to obtain fundamental heat transfer and pressure distribution data over a wide range of high Reynolds numbers and to extend the heat transfer data base to include the range of Reynolds numbers encountered in the Space Shuttle main engine (SSME) turbopump turbines. Specifically, the study aimed to determine (1) the effect of Reynolds number on heat transfer, (2) the effect of upstream turbulence on heat transfer and pressure distribution, and (3) the relationship between heat transfer at high Reynolds numbers and the current data base. The results of this study indicated that Reynolds number and turbulence intensity have a large effect on both the transition from laminar to turbulent flow and the resulting heat transfer. For a given turbulence intensity, heat transfer for all Reynolds numbers at the leading edge can be correlated with the Frossling number developed for lower Reynolds numbers. For a given turbulence intensity, heat transfer for the airfoil surfaces downstream of the leading edge can be approximately correlated with a dimensionless parameter. Comparison of the experimental results were also made with a numerical solution from a two-dimensional Navier-Stokes code.

  3. Heat release rate of wood-plastic composites

    Treesearch

    N. M. Stark; R. H. White; C. M. Clemons

    1997-01-01

    Wood-plastic composites are becoming more important as a material that fulfills recycling needs. In this study, fire performance tests were conducted on several compositions of wood and plastic materials using the Ohio State University rate of heat release apparatus. Test results included five-minute average heat release rate in kW/m2 (HRR avg) and maximum heat release...

  4. The aerodynamic and heat transfer effects of an endwall boundary layer fence in a 90 degree turning square duct

    NASA Astrophysics Data System (ADS)

    Rizzo, Dean H.

    1994-05-01

    This experimental study investigates the utility of boundary layer fences in turbine passage flow. Boundary layer fences have recently been reintroduced as a possible method to achieve favorable effects in turbines. Previous studies have used linear cascades which necessarily introduce a horseshoe vortex resulting from the endwall boundary layer impinging on the blade leading edge. The present study uses a curved square duct that exhibits no horseshoe vortex, but does have the characteristic passage vortices of a turning flow. The turbine passage is simulated to study the interaction effects of the boundary layer fence and the passage flow dominated by the passage vortices. Specifically, a single boundary layer fence of varying dimensions is attached to a heated endwall of the duct. The flow is fully turbulent at the inlet of the duct. Five-hole probe and liquid crystal thermography experimental techniques are used to determine the changes in the aerodynamic flowfield and the heat transfer coefficient of the heated endwall as compared to the same duct with no fence. Hotwire measurements are also presented for the description of the inlet flow field turbulence. This study adds to the currently small volume of information on fences in passage flow in several important aspects. The effect of the fence on the passage vortex is studied in a known flow configuration. The increased pressure losses of thicker (wider) fences are investigated and results show a significant dependence on fence dimensions. Liquid crystal thermography is used to obtain a high-resolution map of the endwall heat transfer coefficient for two fence configurations.

  5. Aerodynamic heating in gaps of thermal protection system tile arrays in laminar and turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Avery, D. E.

    1978-01-01

    An experimental heat-transfer investigation was conducted on two staggered arrays of metallic tiles in laminar and turbulent boundary layers. This investigation was conducted for two purposes. The impingement heating distribution where flow in a longitudinal gap intersects a transverse gap and impinges on a downstream blocking tile was defined. The influence of tile and gap geometries was analyzed to develop empirical relationships for impingement heating in laminar and turbulent boundary layers. Tests were conducted in a high temperature structures tunnel at a nominal Mach number of 7, a nominal total temperature of 1800 K, and free-stream unit Reynolds numbers from 1.0 x 10 million to 4.8 x 10 million per meter. The test results were used to assess the impingement heating effects produced by parameters that include gap width, longitudinal gap length, slope of the tile forward-facing wall, boundary-layer displacement thickness, Reynolds number, and local surface pressure.

  6. Effects of friction and heat conduction on sound propagation in ducts. [analyzing complex aerodynamic noise problems

    NASA Technical Reports Server (NTRS)

    Huerre, P.; Karamcheti, K.

    1976-01-01

    The theory of sound propagation is examined in a viscous, heat-conducting fluid, initially at rest and in a uniform state, and contained in a rigid, impermeable duct with isothermal walls. Topics covered include: (1) theoretical formulation of the small amplitude fluctuating motions of a viscous, heat-conducting and compressible fluid; (2) sound propagation in a two dimensional duct; and (3) perturbation study of the inplane modes.

  7. Measured and predicted aerodynamic heating on a cylinder in wake of AFE configuration at incidence. [Aeroassist Flight Experiment

    NASA Technical Reports Server (NTRS)

    Wells, William L.

    1989-01-01

    Thin-film resistance gages were used to measure cylinder surface heat-transfer rates in the near wake of the Aeroassist Flight Experiment vehicle configuration, while surface-streamline directions were ascertained by the oil-flow techniques under the same configuration and test conditions. Both heat transfer distributions and flow over the entire cylinder surface were influenced by impingement of that portion of the free shear layer originating at the forebody shoulder in the upper symmetry plane. Heating rate distributions predicted with a Navier-Stokes solver computer code were in general agreement with measurements.

  8. Engineering methodology to estimate the aerodynamic heating to the base of the Aeroassist Flight Experiment vehicle

    NASA Technical Reports Server (NTRS)

    Sambamurthi, Jay; Warmbrod, John; Seaford, Mark

    1989-01-01

    An engineering methodology has been developed to predict the convective heating and pressure environments to the base surfaces of the Aeroassist Flight Experiment (AFE) vehicle during its earth aeropass. Data obtained from prior flight vehicles, wind tunnel tests, CFD analysis of AFE, and simple one-dimensional isentropic flow expansion relationships along with standard aeroheating methods were employed. With the exception of one corner, the AFE base surfaces are immersed in separated flow and are, therefore, exposed to heating and pressure that are small compared to the front face of the aerobrake.

  9. Demonstration of EPRI heat-rate improvement guidelines

    SciTech Connect

    Peeples, J.; Higginbotham, D. ); Henry, R.; Warren, S. )

    1991-07-01

    TU Electric used EPRI's Heat Rate Improvement Guidelines to evaluate the thermal performance, determine the magnitude and causes of any heat rate degradation, and recommend corrective actions at its North Lake station, Unit 2. Through the implementation of the short-term improvement activities, full load heat rate improvement of 40 Btu/kWh was achieved. It was also shown that an additional 195 Btu/kWh from long-term improvements was cost-effective. 9 figs., 13 tabs.

  10. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli.

    PubMed

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S; Iguaz, Asunción; Periago, Paula M; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing.

  11. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli

    PubMed Central

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S.; Iguaz, Asunción; Periago, Paula M.; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing. PMID:27563300

  12. Influence of radiant energy exchange on the determination of convective heat transfer rates to Orbiter leeside surfaces during entry

    NASA Technical Reports Server (NTRS)

    Throckmorton, D. A.

    1982-01-01

    Temperatures measured at the aerodynamic surface of the Orbiter's thermal protection system (TPS), and calorimeter measurements, are used to determine heating rates to the TPS surface during atmospheric entry. On the Orbiter leeside, where convective heating rates are low, it is possible that a significant portion of the total energy input may result from solar radiation, and for the wing, cross radiation from the hot (relatively) Orbiter fuselage. In order to account for the potential impact of these sources, values of solar- and cross-radiation heat transfer are computed, based upon vehicle trajectory and attitude information and measured surface temperatures. Leeside heat-transfer data from the STS-2 mission are presented, and the significance of solar radiation and fuselage-to-wing cross-radiation contributions to total energy input to Orbiter leeside surfaces is assessed.

  13. Influence of radiant energy exchange on the determination of convective heat transfer rates to Orbiter leeside surfaces during entry

    NASA Technical Reports Server (NTRS)

    Throckmorton, D. A.

    1982-01-01

    Temperatures measured at the aerodynamic surface of the Orbiter's thermal protection system (TPS), and calorimeter measurements, are used to determine heating rates to the TPS surface during atmospheric entry. On the Orbiter leeside, where convective heating rates are low, it is possible that a significant portion of the total energy input may result from solar radiation, and for the wing, cross radiation from the hot (relatively) Orbiter fuselage. In order to account for the potential impact of these sources, values of solar- and cross-radiation heat transfer are computed, based upon vehicle trajectory and attitude information and measured surface temperatures. Leeside heat-transfer data from the STS-2 mission are presented, and the significance of solar radiation and fuselage-to-wing cross-radiation contributions to total energy input to Orbiter leeside surfaces is assessed.

  14. The global joule heat production rate and the AE index

    NASA Technical Reports Server (NTRS)

    Wei, S.; Ahn, B.-H.; Akasofu, S.-I.

    1985-01-01

    The degree of accuracy with which the AE index may be used as a measure of the joule heat production rate is evaluated for a typical substorm event on March 18, 1978, by estimating the global joule heat production rate as a function of time on the basis of data obtained from the IMS's six meridian chains. It is found that, although the AE index is statistically linearly related to the global joule heat production rate, caution is required when one assumes that details of AE index time variations during individual events are representative of those of the joule heat production rate.

  15. Aerodynamic heating to the gaps and surfaces of simulated reusable-surface-insulation tile arrays in turbulent flow at Mach 6.6

    NASA Technical Reports Server (NTRS)

    Weinstein, I.; Avery, D. E.; Chapman, A. J.

    1975-01-01

    An experimental investigation was made on a simulated reusable-surface-insulation tile array in a turbulent boundary layer to determine aerodynamic-heating distributions representative of those expected on the surface of the shuttle orbiter during earth entry due to the presence of longitudinal and transverse surface gaps. The tests were conducted in an 8-foot high-temperature structures tunnel in a test medium of methane-air combustion products at a nominal Mach number of 6.6 and over a free-stream Reynolds number range from 2,000,000 to 4,900,000 per meter (600,000 to 1,500,000 per foot). The results were used to assess the aerodynamic heating effects produced by parameters that include gap width, boundary-layer displacement thickness, in-line and staggered tile arrangement, and tile protrusion.

  16. Testing, analysis, and code verification of aerodynamics and heat transfer related to turbomachinery

    NASA Technical Reports Server (NTRS)

    King, Paul I.

    1991-01-01

    Discussed here are the writing of a data acquisition code and the installation and testing of new pressure and temperature instrumentation to be used in the testing and evaluation of miniature heat flux sensors. A brief summary of the problem which led to the need for these tests is presented as well as a proposed data acquisition program and the results of investigations of two measurement systems, the Omega OM-900 temperature sensing system and the Scani-Valve Hyscan pressure measurement system.

  17. An Experimental and Numerical Investigation of Endwall Aerodynamics and Heat Transfer in a Gas Turbine Nozzle Guide Vane with Slot Film Cooling

    NASA Astrophysics Data System (ADS)

    Alqefl, Mahmood Hasan

    In many regions of the high-pressure gas turbine, film cooling flows are used to protect the turbine components from the combustor exit hot gases. Endwalls are challenging to cool because of the complex system of secondary flows that disturb surface film coolant coverage. The secondary flow vortices wash the film coolant from the surface into the mainstream significantly decreasing cooling effectiveness. In addition to being effected by secondary flow structures, film cooling flow can also affect these structures by virtue of their momentum exchange. In addition, many studies in the literature have shown that endwall contouring affects the strength of passage secondary flows. Therefore, to develop better endwall cooling schemes, a good understanding of passage aerodynamics and heat transfer as affected by interactions of film cooling flows with secondary flows is required. This experimental and computational study presents results from a linear, stationary, two-passage cascade representing the first stage nozzle guide vane of a high-pressure gas turbine with an axisymmetrically contoured endwall. The sources of film cooling flows are upstream combustor liner coolant and endwall slot film coolant injected immediately upstream of the cascade passage inlet. The operating conditions simulate combustor exit flow features, with a high Reynolds number of 390,000 and approach flow turbulence intensity of 11% with an integral length scale of 21% of the chord length. Measurements are performed with varying slot film cooling mass flow to mainstream flow rate ratios (MFR). Aerodynamic effects are documented with five-hole probe measurements at the exit plane. Heat transfer is documented through recovery temperature measurements with a thermocouple. General secondary flow features are observed. Total pressure loss measurements show that varying the slot film cooling MFR has some effects on passage loss. Velocity vectors and vorticity distributions show a very thin, yet intense

  18. Predicted thermal response of a cryogenic fuel tank exposed to simulated aerodynamic heating profiles with different cryogens and fill levels

    NASA Technical Reports Server (NTRS)

    Hanna, Gregory J.; Stephens, Craig A.

    1991-01-01

    A two dimensional finite difference thermal model was developed to predict the effects of heating profile, fill level, and cryogen type prior to experimental testing the Generic Research Cryogenic Tank (GRCT). These numerical predictions will assist in defining test scenarios, sensor locations, and venting requirements for the GRCT experimental tests. Boiloff rates, tank-wall and fluid temperatures, and wall heat fluxes were determined for 20 computational test cases. The test cases spanned three discrete fill levels and three heating profiles for hydrogen and nitrogen.

  19. Measurement and calculation of end wall heat transfer and aerodynamics on a nozzle guide vane in annular cascade

    NASA Astrophysics Data System (ADS)

    Harvey, N. W.; Jones, T. V.

    1990-06-01

    Detailed measurements of surface static pressures and heat transfer rates on the aerofoil and hub end wall of an annular nozzle guide vane (in the absence of a downstream rotor) are presented. Heat transfer rates have been measured using thin film gages in an annular cascade in the Pyestock Isentropic Light Piston Casccade. Test Mach numbers, Reynolds numbers and cascade geometry are fully representative of engine conditions. The results of 3D calculations of surface Mach number and 2D calculations of aerofoil heat transfer are presented and compared with the measurements. A new method of calculating end wall heat transfer using the axisymmetric analogue for three-dimensional boundary layers is described in detail. The method uses a 3D Euler solver to calculate the inviscid surface streamlines along which heat transfer coefficients are calculated. The metric coefficient which describes the lateral convergence or divergence of the streamlines is used to include three-dimensional effects in the calculation. The calculated heat transfer rates compare well with the measured values. Reference is made to surface flow visualization in the interpretation of the results.

  20. The Experimental Measurement of Aerodynamic Heating About Complex Shapes at Supersonic Mach Numbers

    NASA Technical Reports Server (NTRS)

    Neumann, Richard D.; Freeman, Delma C.

    2011-01-01

    In 2008 a wind tunnel test program was implemented to update the experimental data available for predicting protuberance heating at supersonic Mach numbers. For this test the Langley Unitary Wind Tunnel was also used. The significant differences for this current test were the advances in the state-of-the-art in model design, fabrication techniques, instrumentation and data acquisition capabilities. This current paper provides a focused discussion of the results of an in depth analysis of unique measurements of recovery temperature obtained during the test.

  1. Aerodynamic Mixing Downstream from Line Source of Heat in High-intensity Sound Field

    NASA Technical Reports Server (NTRS)

    Mickelson, William R; Baldwin, Lionel V

    1956-01-01

    Theory and measurement showed that the heat wake downstream from a line source is displaced by a transverse standing sound wave in a manner similar to a flag waving in a harmonic mode. With a 147 db, 104 cps standing wave, time-mean temperatures were reduced by an order of magnitude except near the displacement-pattern nodal points. The theory showed that a 161 db, 520 cps standing wave considerably increased the mixing in both the time-mean and instantaneous senses.

  2. Characteristic thermal constant and dimensionless heating rate. The links to optimum heating rate in GC

    PubMed

    Blumberg; Klee

    2000-09-01

    An initial step in the quest of deriving a generalized approach to optimization of a temperature program in gas chromatography is presented. Central to this is the introduction of a dimensionless heating rate, r. As a first step to defining r, a characteristic thermal constant, thetachar, defined as thetachar = -dT/dk at k = 1, where T and k are, respectively, column temperature and solute retention factor, is introduced and evaluated for our own experimental data and for thermodynamic data from the literature. It was determined that, for silicone stationary phases with a phase ratio of 250, thetachar ranged from about 23 degrees C for low molecular weight hydrocarbons such as dimethylpropane to about 45 degrees C for high molecular weight pesticides such as mirex. It was also found that, for a particular solute and a stationary phase type, a 2 orders of magnitude increase in the film thickness caused only about a 2-fold increase in the characteristic thermal constant. Using thetachar as a fundamental temperature unit in GC and void time as a fundamental time unit, a dimensionless heating rate is introduced and its potential utility for the evaluation of the separation-speed tradeoffs in a temperature-programmed GC is demonstrated.

  3. The effects of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of a large-scale rotating turbine model, volume 1

    NASA Technical Reports Server (NTRS)

    Dring, R. P.; Blair, M. F.; Joslyn, H. D.; Power, G. D.; Verdon, J. M.

    1987-01-01

    A combined experimental and analytical program was conducted to examine the effects of inlet turbulence on airfoil heat transfer. Heat transfer measurements were obtained using low conductivity airfoils with miniature thermocouples welded to a thin, electrically heated surface skin. Heat transfer data were acquired for various combinations of low or high inlet turbulence intensity, flow coefficient (incidence), first-stator/rotor axial spacing, Reynolds number, and relative circumferential position of the first and second stators. Aerodynamic measurements include distributions of the mean and fluctuating velocities at the turbine inlet and, for each airfoil row, midspan airfoil surface pressures and circumferential distributions of the downstream steady state pressures and fluctuating velocities. Analytical results include airfoil heat transfer predictions and a examination of solutions of the unstead boundary layer equipment.

  4. Charring rate of wood exposed to a constant heat flux

    Treesearch

    R. H. White; H. C. Tran

    1996-01-01

    A critical factor in the fire endurance of a wood member is its rate of charring. Most available charring rate data have been obtained using the time-temperature curves of the standard fire resistance tests (ASTM E 119 and ISO 834) to define the fire exposure. The increased use of heat release calorimeters using exposures of constant heat flux levels has broadened the...

  5. Assessment of heating rate and non-uniform heating in domestic microwave ovens.

    PubMed

    Pitchai, Krishnamoorthy; Birla, Sohan L; Jones, David; Subbiah, Jeyamkondan

    2012-01-01

    Due to the inherent nature of standing wave patterns of microwaves inside a domestic microwave oven cavity and varying dielectric properties of different food components, microwave heating produces non-uniform distribution of energy inside the food. Non-uniform heating is a major food safety concern in not-ready-to-eat (NRTE) microwaveable foods. In this study, we present a method for assessing heating rate and non-uniform heating in domestic microwave ovens. In this study a custom designed container was used to assess heating rate and non-uniform heating of a range of microwave ovens using a hedgehog of 30 T-type thermocouples. The mean and standard deviation of heating rate along the radial distance and sector of the container were measured and analyzed. The effect of the location of rings and sectors was analyzed using ANOVA to identify the best location for placing food on the turntable. The study suggested that the best location to place food in a microwave oven is not at the center but near the edge of the turntable assuming uniform heating is desired. The effect of rated power and cavity size on heating rate and non-uniform heating was also studied for a range of microwave ovens. As the rated power and cavity size increases, heating rate increases while non-uniform heating decreases. Sectors in the container also influenced heating rate (p < 0.0001), even though it did not have clear trend on heating rate. In general, sectors close to the magnetron tend to heat slightly faster than sectors away from the magnetron. However, the variation in heating rate among sectors was only 2 degrees C/min and considered not practically important. Overall heating performance such as mean heating rate and non-uniform heating did not significantly vary between the two replications that were performed 4 h apart. However, microwave ovens were inconsistent in producing the same heating patterns between the two replications that were performed 4 h apart.

  6. Burning rate of solid wood measured in a heat release rate calorimeter

    Treesearch

    H. C. Tran; R. H. White

    1992-01-01

    Burning rate is a key factor in modeling fire growth and fire endurance of wood structures. This study investigated the burning rate of selected wood materials as determined by heat release, mass loss and charring rates. Thick samples of redwood, southern pine, red oak and basswood were tested in a heat release rate calorimeter. Results on ignitability and average beat...

  7. The effects of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of a large-scale rotating turbine model. Part 4: Aerodynamic data tabulation

    NASA Technical Reports Server (NTRS)

    Dring, R. P.; Joslyn, H. D.; Blair, M. F.

    1987-01-01

    A combined experimental and analytical program was conducted to examine the effects of inlet turbulence and airfoil heat transfer. The experimental portion of the study was conducted in a large-scale (approx. 5X engine), ambient temperature, rotating turbine model configured in both single-stage and stage-and-a-half arrangements. Heat transfer measurements were obtained using low-conductivity airfoils with miniature thermocouples welded to a thin, electrically heated surface skin. Heat transfer data were acquired for various combinations of low or high inlet turbulence intensity, flow coefficient, first stator-rotor axial spacing, Reynolds number and relative circumferential position of the first and second stators. Aerodynamic measurements obtained include distributions of the mean and fluctuating velocities at the turbine inlet and, for each airfoil row, midspan airfoil surface pressures and circumferential distributions of the downstream steady state pressures and fluctuating velocities. Results include airfoil heat transfer predictions produced using existing 2-D boundary layer computation schemes and an examination of solutions of the unsteady boundary layer equations.

  8. Spatially resolved heat release rate measurements in turbulent premixed flames

    SciTech Connect

    Ayoola, B.O.; Kaminski, C.F.; Balachandran, R.; Mastorakos, E.; Frank, J.H.

    2006-01-01

    Heat release rate is a fundamental property of great importance for the theoretical and experimental elucidation of unsteady flame behaviors such as combustion noise, combustion instabilities, and pulsed combustion. Investigations of such thermoacoustic interactions require a reliable indicator of heat release rate capable of resolving spatial structures in turbulent flames. Traditionally, heat release rate has been estimated via OH or CH radical chemiluminescence; however, chemiluminescence suffers from being a line-of-sight technique with limited capability for resolving small-scale structures. In this paper, we report spatially resolved two-dimensional measurements of a quantity closely related to heat release rate. The diagnostic technique uses simultaneous OH and CH{sub 2}O planar laser-induced fluorescence (PLIF), and the pixel-by-pixel product of the OH and CH{sub 2}O PLIF signals has previously been shown to correlate well with local heat release rates. Results from this diagnostic technique, which we refer to as heat release rate imaging (HR imaging), are compared with traditional OH chemiluminescence measurements in several flames. Studies were performed in lean premixed ethylene flames stabilized between opposed jets and with a bluff body. Correlations between bulk strain rates and local heat release rates were obtained and the effects of curvature on heat release rate were investigated. The results show that the heat release rate tends to increase with increasing negative curvature for the flames investigated for which Lewis numbers are greater than unity. This correlation becomes more pronounced as the flame gets closer to global extinction.

  9. Study of Uncertainties of Predicting Space Shuttle Thermal Environment. [impact of heating rate prediction errors on weight of thermal protection system

    NASA Technical Reports Server (NTRS)

    Fehrman, A. L.; Masek, R. V.

    1972-01-01

    Quantitative estimates of the uncertainty in predicting aerodynamic heating rates for a fully reusable space shuttle system are developed and the impact of these uncertainties on Thermal Protection System (TPS) weight are discussed. The study approach consisted of statistical evaluations of the scatter of heating data on shuttle configurations about state-of-the-art heating prediction methods to define the uncertainty in these heating predictions. The uncertainties were then applied as heating rate increments to the nominal predicted heating rate to define the uncertainty in TPS weight. Separate evaluations were made for the booster and orbiter, for trajectories which included boost through reentry and touchdown. For purposes of analysis, the vehicle configuration is divided into areas in which a given prediction method is expected to apply, and separate uncertainty factors and corresponding uncertainty in TPS weight derived for each area.

  10. Aerodynamic stability and heating analyses for the aeroassist flight experiment vehicle

    NASA Technical Reports Server (NTRS)

    Mcgary, J.; Li, Chien P.

    1989-01-01

    Since ground based flow simulations are presently unable to model flight conditions expected for AOTVs (Aeroassist Orbital Transfer Vehicle) and other hypersonic space vehicles, computer codes are being developed to provide design parameters necessary for structure, guidance, and control aspects. Over the past four years, VRFLO (Viscous Reactive Flow) has been written to model finite-rate chemistry and viscous effects for a variety of aerobrake bodies. VRFLO includes a number of unique features that are summarized as follows: (1) Grid generation is an integral part of the code for several aerobrake configurations which includes the wake flow region; (2) The formulation is valid for three air chemical models; (3) An ADI central difference technique is used to solve the Navier-Stokes and species continuity equations in split groups; and (4) Grid density and numerical damping are minimized by shock-fitting and conformal mapping of body points.

  11. A time Fourier analysis of zonal averaged ozone heating rates

    NASA Technical Reports Server (NTRS)

    Wang, P.-H.; Wu, M.-F.; Deepak, A.; Hong, S.-S.

    1981-01-01

    A time-Fourier analysis is presented for the yearly variation of the zonal averaged ozone heating rates in the middle atmosphere based on a model study. The ozone heating rates are determined by utilizing two-dimensional ozone distributions, the altitude and latitude, and by including the effect of the curved earth's atmosphere. In addition, assumptions are introduced to the yearly variations of the ozone distributions due to the lack of sufficient existing ozone data. Among other results, it is shown that the first harmonic component indicates that the heating rates are completely out of phase between the northern and southern hemispheres. The second Fourier component shows a symmetric pattern with respect to the equator, as well as five distinct local extreme values of the ozone heating rate. The third harmonic component shows a pattern close to that of the first component except in the regions above 70 deg between 45-95 km in both hemispheres.

  12. Coal-Fired Power Plant Heat Rate Reductions

    EPA Pesticide Factsheets

    View a report that identifies systems and equipment in coal-fired power plants where efficiency improvements can be realized, and provides estimates of the resulting net plant heat rate reductions and costs for implementation.

  13. Aerodynamic Heating and Fatigue

    NASA Technical Reports Server (NTRS)

    Kroll, Wilhelmina D.

    1959-01-01

    A review of the physical condition's under which future airplanes will operate has been made and the necessity for considering fatigue in the design has been established. A survey of the literature shows what phases of elevated-temperature fatigue have been investigated. Other studies that would yield data of particular interest to the designer of aircraft structures are indicated.

  14. Temperature and heating rate of ion crystals in Penning traps

    SciTech Connect

    Jensen, Marie J.; Hasegawa, Taro; Bollinger, John J.

    2004-09-01

    We have determined the temperature and heating rate of laser-cooled ions in a Penning trap using Doppler laser spectroscopy. Between 10{sup 4} and 10{sup 6} {sup 9}Be{sup +} ions are trapped in a Penning trap and Doppler laser cooled to temperatures of a few millikelvin, where they form ion crystals. This system is an example of a strongly coupled one-component plasma. The ion temperature was measured as a function of time after turning off the laser-cooling. In the solid phase, we measured a heating rate of {approx}65 mK/s. Information about possible heating mechanisms was obtained directly from temperature measurements, and also from measurements of the rate of radial expansion of the ion plasma. We determined that the observed heating is due to collisions with the {approx}4x10{sup -9} Pa residual gas of our vacuum system.

  15. Measurements of Aerodynamic Heat Transfer and Boundary-Layer Transition on a 10 deg Cone in Free Flight at Supersonic Mach Numbers up to 5.9

    NASA Technical Reports Server (NTRS)

    Rumsey, Charles B.; Lee, Dorothy B.

    1961-01-01

    Measurements of aerodynamic heat transfer have been made at six stations on the 40-inch-long 10 deg. total-angle conical nose of a rocket- propelled model which was flight tested at Mach numbers up to 5.9. are presented for a range of local Mach number just outside the bound- ary layer on the cone from 1.57 to 5.50, and a range of local Reynolds number from 6.6 x 10(exp 6) to 55.2 x 10(exp 6) based on length from the nose tip.

  16. Design and demonstration of heat pipe cooling for NASP and evaluation of heating methods at high heating rates

    SciTech Connect

    Merrigan, M.A.; Sena, J.T.

    1989-01-01

    An evaluation of two heating methods for demonstration of NASP leading edge heat pipe technology was conducted. The heating methods were and rf induction heated plasma jet and direct rf induction. Tests were conducted to determine coupling from the argon plasma jet on a surface physically similar to a heat pipe. A molybdenum tipped calorimeter was fabricated and installed in an rf induction heated plasma jet for the test. The calorimetric measurements indicated a maximum power coupling of approximately 500 W/cm{sup 2} with the rf plasma jet. The effect of change in gas composition on the heating rate was investigated using helium. An alternative to the plasma heating of a heat pipe tip, an rf concentrator was evaluated for coupling to the hemispherical tip of a heat pipe. A refractory metal heat pipe was designed, fabricated, and tested for the evaluation. The heat pipe was designed for operation at 1400 to 1900 K with power input to 1000 W/cm{sup 2} over a hemispherical nose tip. Power input of 800 W/cm{sup 2} was demonstrated using the rf concentrator. 2 refs., 13 figs.

  17. r-PROCESS LANTHANIDE PRODUCTION AND HEATING RATES IN KILONOVAE

    SciTech Connect

    Lippuner, Jonas; Roberts, Luke F.

    2015-12-20

    r-process nucleosynthesis in material ejected during neutron star mergers may lead to radioactively powered transients called kilonovae. The timescale and peak luminosity of these transients depend on the composition of the ejecta, which determines the local heating rate from nuclear decays and the opacity. Kasen et al. and Tanaka and Hotokezaka pointed out that lanthanides can drastically increase the opacity in these outflows. We use the new general-purpose nuclear reaction network SkyNet to carry out a parameter study of r-process nucleosynthesis for a range of initial electron fractions Y{sub e}, initial specific entropies s, and expansion timescales τ. We find that the ejecta is lanthanide-free for Y{sub e} ≳ 0.22−0.30, depending on s and τ. The heating rate is insensitive to s and τ, but certain, larger values of Y{sub e} lead to reduced heating rates, due to individual nuclides dominating the heating. We calculate approximate light curves with a simplified gray radiative transport scheme. The light curves peak at about a day (week) in the lanthanide-free (-rich) cases. The heating rate does not change much as the ejecta becomes lanthanide-free with increasing Y{sub e}, but the light-curve peak becomes about an order of magnitude brighter because it peaks much earlier when the heating rate is larger. We also provide parametric fits for the heating rates between 0.1 and 100 days, and we provide a simple fit in Y{sub e}, s, and τ to estimate whether or not the ejecta is lanthanide-rich.

  18. r-process Lanthanide Production and Heating Rates in Kilonovae

    NASA Astrophysics Data System (ADS)

    Lippuner, Jonas; Roberts, Luke F.

    2015-12-01

    r-process nucleosynthesis in material ejected during neutron star mergers may lead to radioactively powered transients called kilonovae. The timescale and peak luminosity of these transients depend on the composition of the ejecta, which determines the local heating rate from nuclear decays and the opacity. Kasen et al. and Tanaka & Hotokezaka pointed out that lanthanides can drastically increase the opacity in these outflows. We use the new general-purpose nuclear reaction network SkyNet to carry out a parameter study of r-process nucleosynthesis for a range of initial electron fractions Ye, initial specific entropies s, and expansion timescales τ. We find that the ejecta is lanthanide-free for Ye ≳ 0.22-0.30, depending on s and τ. The heating rate is insensitive to s and τ, but certain, larger values of Ye lead to reduced heating rates, due to individual nuclides dominating the heating. We calculate approximate light curves with a simplified gray radiative transport scheme. The light curves peak at about a day (week) in the lanthanide-free (-rich) cases. The heating rate does not change much as the ejecta becomes lanthanide-free with increasing Ye, but the light-curve peak becomes about an order of magnitude brighter because it peaks much earlier when the heating rate is larger. We also provide parametric fits for the heating rates between 0.1 and 100 days, and we provide a simple fit in Ye, s, and τ to estimate whether or not the ejecta is lanthanide-rich.

  19. Coal plasticity at high heating rates and temperatures

    SciTech Connect

    Darivakis, G.S.; Peters, W.A.; Howard, J.B.

    1990-01-01

    The broad objective of this project is to obtain improved, quantitative understanding of the transient plasticity of bituminous coals under high heating rates and other reaction and pretreatment conditions of scientific and practical interest. To these ends the research plan is to measure the softening and resolidification behavior of two US bituminous coals with a rapid-heating, fast response, high-temperature coal plastometer, previously developed in this laboratory. Specific measurements planned for the project include determinations of apparent viscosity, softening temperature, plastic period, and resolidificationtime for molten coal: (1) as a function of independent variations in coal type, heating rate, final temperature, gaseous atmosphere (inert, 0{sub 2} or H{sub 2}), and shear rate; and (2) in exploratory runs where coal is pretreated (preoxidation, pyridine extraction, metaplast cracking agents), before heating. The intra-coal inventory and molecular weight distribution of pyridine extractables will also be measured using a rapid quenching, electrical screen heater coal pyrolysis reactor. The yield of extractables is representative of the intra-coal inventory of plasticing agent (metaplast) remaining after quenching. Coal plasticity kinetics will then be mathematically modeled from metaplast generation and depletion rates, via a correlation between the viscosity of a suspension and the concentration of deformable medium (here metaplast) in that suspension. Work during this reporting period has been concerned with re-commissioning the rapid heating rate plastometer apparatus.

  20. Selection, Evaluation, And Rating of Compact Heat exchangers

    SciTech Connect

    Carlson, Matt

    2014-10-07

    SEARCH determines and optimizes the design of a compact heat exchanger for specified process conditions. The user specifies process boundary conditions including the fluid state and flow rate and SEARCH will determine the optimum flow arrangement, channel geometry, and mechanical design for the unit. Fluids are modeled using NUST Refprop or tabulated values. A variety of thermal-hydraulic correlations are available including user-defined equations to accurately capture the heat transfer and pressure drop behavior of the process flows.

  1. Inverse bremsstrahlung heating rate for dense plasmas in laser fields

    NASA Astrophysics Data System (ADS)

    Dey, R.; Roy, A. C.

    2013-07-01

    We report a theoretical analysis of inverse bremsstrahlung heating rate in the eikonal approximation. The present analysis is performed for a dense plasma using the screened electron-ion interaction potential for the ion charge state Zi = 1 and for both the weak and strong plasma screening cases. We have also compared the eikonal results with the first Born approximation (FBA) [M. Moll et al., New J. Phys. 14, 065010 (2012)] calculation. We find that the magnitudes of inverse bremsstrahlung heating rate within the eikonal approximation (EA) are larger than the FBA values in the weak screening case (κ = 0.03 a.u.) in a wide range of field strength for three different initial electron momenta (2, 3, and 4 a.u.). But for strong screening case (κ = 0.3 a.u.), the heating rates predicted by the two approximations do not differ much after reaching their maximum values. Furthermore, the individual contribution of photoemission and photoabsorption processes to heating rate is analysed for both the weak and strong screening cases. We find that the single photoemission and photoabsorption rates are the same throughout the field strength while the multiphoton absorption process dominates over the multiphoton emission process beyond the field strength ≈ 4×108 V/cm. The present study of the dependence of heating rate on the screening parameter ranging from 0.01 to 20 shows that whereas the heating rate predicted by the EA is greater than the FBA up to the screening parameter κ = 0.3 a.u., the two approximation methods yield results which are nearly identical beyond the above value.

  2. Inverse bremsstrahlung heating rate for dense plasmas in laser fields

    SciTech Connect

    Dey, R.; Roy, A. C.

    2013-07-15

    We report a theoretical analysis of inverse bremsstrahlung heating rate in the eikonal approximation. The present analysis is performed for a dense plasma using the screened electron-ion interaction potential for the ion charge state Z{sub i} = 1 and for both the weak and strong plasma screening cases. We have also compared the eikonal results with the first Born approximation (FBA) [M. Moll et al., New J. Phys. 14, 065010 (2012)] calculation. We find that the magnitudes of inverse bremsstrahlung heating rate within the eikonal approximation (EA) are larger than the FBA values in the weak screening case (κ = 0.03 a.u.) in a wide range of field strength for three different initial electron momenta (2, 3, and 4 a.u.). But for strong screening case (κ = 0.3 a.u.), the heating rates predicted by the two approximations do not differ much after reaching their maximum values. Furthermore, the individual contribution of photoemission and photoabsorption processes to heating rate is analysed for both the weak and strong screening cases. We find that the single photoemission and photoabsorption rates are the same throughout the field strength while the multiphoton absorption process dominates over the multiphoton emission process beyond the field strength ≈ 4×10{sup 8} V/cm. The present study of the dependence of heating rate on the screening parameter ranging from 0.01 to 20 shows that whereas the heating rate predicted by the EA is greater than the FBA up to the screening parameter κ = 0.3 a.u., the two approximation methods yield results which are nearly identical beyond the above value.

  3. Experimental Investigation of Heat transfer rate of Nano fluids using a Shell and Tube Heat exchanger

    NASA Astrophysics Data System (ADS)

    SIVA ESWARA RAO, M.; SREERAMULU, DOWLURU; ASIRI NAIDU, D.

    2016-09-01

    Nano fluids are used for increasing thermal properties in heat transfer equipment like heat exchangers, radiators etc. This paper investigates the heat transfer rate of Nano fluids using a shell and tube heat exchanger in single and multi tubes under turbulent flow condition by a forced convection mode. Alumina Nanoparticles are prepared by using Sol-Gel method. Heat transfer rate increases with decreasing particle size. In this experiment Alumina Nano particles of about 22 nm diameter used. Alumina Nano fluids are prepared with different concentrations of Alumina particles (0.13%, 0.27%, 0.4%, and 0.53%) with water as a base fluid using ultra-sonicator. Experiment have been conducted on shell and tube heat exchanger for the above concentrations on parallel and counter flow conditions by keeping constant inlet temperatures and mass flow rate. The result shows that the heat transfer rate is good compared to conventional fluids. The properties of Nano fluids and non-dimensional numbers have been calculated.

  4. SEAC4RS Aerosol Radiative Effects and Heating Rates

    NASA Astrophysics Data System (ADS)

    Cochrane, S.; Schmidt, S.; Redemann, J.; Hair, J. W.; Ferrare, R. A.; Segal-Rosenhaimer, M.; LeBlanc, S. E.

    2015-12-01

    We will present (a) aerosol optical properties, (b) aerosol radiative forcing, (c) aerosol and gas absorption and heating rates, and (d) spectral surface albedo for cases from August 19th and 26th of the SEAC4RS mission. This analysis is based on irradiance data from the Solar Spectral Flux Radiometer (SSFR), spectral aerosol optical depth from the Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR), and extinction profiles from the DIAL/High Spectral Resolution Lidar (HSRL). We derive spectrally resolved values of single scattering albedo, asymmetry parameter, and surface albedo from the data, and determine profiles of absorption and heating rate segregated by absorber (aerosol and gas).

  5. Aerodynamic Heating and the Deflection of Drops by an Obstacle in an Air Stream in Relation to Aircraft Icing

    DTIC Science & Technology

    1940-10-01

    this document, please feel free to contact our Directorate of User Services at [703] 767-9066/9068 or DSN 427-9066/9068. Do Not Return This Document...tho lower prossure In order to obtain a comparison of the tost results with thoery , the temperature rises across the boundary layer were computed...not experience the moat severe lcla?; conditions, which occur at atmospheric tem- peratures only a few degrees below froozlns* Aerodynamic

  6. HEATING RATE SCALING OF TURBULENCE IN THE PROTON KINETIC REGIME

    SciTech Connect

    Vasquez, Bernard J.

    2015-06-10

    Three-dimensional numerical hybrid simulations with particle protons and quasi-neutralizing, fluid electrons are conducted for a freely decaying turbulence. The main results are obtained from a series of runs as a function of the initial total rms fluctuation amplitude. In the turbulent phase and at a corresponding nonlinear time dependent on the amplitude, the scaling of the proton perpendicular heating rate is examined as a function of the spectral value of the electron bulk perpendicular speed integrated in wavenumbers about the inverse thermal proton gyroradius. The perpendicular direction is relative to the background magnetic field. The obtained spectral value is normalized to the proton thermal speed and ranges from 0.06 to 0.16. The scaling of the perpendicular heating rate with this spectral value is fitted with a power law, which has an index of −3.3 ± 0.2. The fit is consistent with the scaling of the total heating rate as a function of total rms amplitude, which has an index of −3.06 ± 0.12. The power-law index is near the turbulent hydrodynamic-like prediction for the energy cascade rate as a function of amplitude. The heating rate, then, obeys a power law with amplitude or spectral value regardless of whether that quantity is evaluated at large scales or at the proton gyroradius scales.

  7. Radiative heating and cooling rates in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Gille, John C.; Lyjak, Lawrence V.

    1986-01-01

    One of the limitations to the accurate calculation of radiative heating and cooling rates in the stratosphere and mesosphere has been the lack of accurate data on the atmospheric temperature and composition. Data from the LIMS experiment on Nimbus-7 has been extended to the South Pole with the aid of other observations. The data have been used as input to codes developed by Ramanathan and Dickinson to calculate the individual components and the net radiative heating rates from 100-0.1 mb. Solar heating due to ozone, nitrogen dioxide, carbon dioxide, water vapor and oxygen is shown to be nearly balanced by cooling in the thermal infrared spectral region due to carbon dioxide, ozone and water vapor. In the lower stratosphere, infrared transfer by ozone leads to heating that is sensitive to the distribution of tropospheric ozone, clouds and water vapor. The heating and cooling rates are adjusted slightly in order to satisfy the global mass balance. The results are in qualitative agreement with earlier calculations, but show additional detail. There is as strong temporal and vertical variation of cooling in the tropics. Radiative relaxation times are as short as 7 days or less at the stratopause.

  8. Reaction sintering of zinc ferrite during constant rates of heating

    SciTech Connect

    Rahaman, M.N. . Ceramic Engineering Dept.); De Jonghe, L.C. . Lawrence Berkeley Lab.)

    1993-07-01

    The reaction sintering of equimolar quantities of zinc oxide and ferric oxide was investigated under conditions of constant rates of heating and the data were compared with those for a calcined, single-phase zinc ferrite powder. For the heating rate of 1C/min, the densifications of the reaction-sintered sample and the calcined sample were approximately the same. However, as the heating rate increased, the density at any temperature increased slightly for the reaction-sintered sample but decreased slightly for the calcined powder. The factors responsible for this slight difference in sintering between the reaction-sintered sample and the calcined sample are discussed. For the constant heating rates used, the reaction was completed prior to any significant densification. Relative densities of >95% were obtained for both the reaction-sintered sample and the calcined sample under identical sintering conditions (1-10C/min to 1350C). Reaction sintering in a steep temperature gradient produced a nearly fully dense body prior to complete reaction; a composite microstructure consisting of fine zinc oxide grains in matrix of zinc ferrite was obtained.

  9. High heating rate thermal desorption for molecular surface sampling

    SciTech Connect

    Ovchinnikova, Olga S.; Van Berkel, Gary J.

    2016-03-29

    A method for analyzing a sample having at least one analyte includes the step of heating the sample at a rate of at least 10.sup.6 K/s to thermally desorb at least one analyte from the sample. The desorbed analyte is collected. The analyte can then be analyzed.

  10. Flash Heating of Crustal Rocks at Seismic Slip Rates

    NASA Astrophysics Data System (ADS)

    Goldsby, D. L.; Spagnuolo, E.; Smith, S. A.; Beeler, N. M.; Tullis, T. E.; Di Toro, G.; Nielsen, S. B.

    2012-12-01

    Recent experiments have demonstrated that rocks undergo extreme frictional weakening at near-earthquake slip rates due to the thermal degradation of the strength, or even melting, of microscopic asperity contacts on their sliding surfaces (Goldsby and Tullis, 2012). These previous experiments, conducted at constant normal stress and slip rates of up to ~0.4 m/s, revealed a 1/V dependence of friction on slip rate above a characteristic weakening velocity, Vw, in accord with theories of flash heating (e.g., Rice, 2006). The weakening velocity obtains values of ~0.1 m/s for many crustal silicate rocks (Goldsby and Tullis, 2012). Here we test two further predictions of flash-heating theory - that the degree of weakening saturates at slip rates approaching 1 m/s, and that the weakening behavior due to flash heating is independent of normal stress - by testing samples at slip rates of up to 1 m/s at different normal stresses. Experiments were conducted in a 1-atm, high-velocity friction apparatus at the Istituto Nazionale di Geofisica e Vulcanologia in Rome. A sample consisted of a pair of hollow cylinders of Westerly granite or Frederick diabase subjected to a nominally constant normal stress of from 1 to 30 MPa and subjected to a variety of rate-stepping sequences. Data were acquired at rates of up to 1 MHz. As predicted, the experiments demonstrate that the degree of weakening due to flash heating saturates at slip rates approaching 1 m/s; in a few cases, friction even increases slightly with increasing slip rate near 1 m/s. The experiments also demonstrate that, within the scatter of the data, the value of Vw and the friction coefficient in the weakened state is independent of normal stress, the expected result if average contact sizes and contact stresses are independent of normal stress. The data thus further corroborate existing theories and experimental data for flash heating, allowing for a more reliable determination of the conditions under which flash heating

  11. Directly Measured Heating Rates of a Tropical Subvisible Cirrus Cloud

    NASA Technical Reports Server (NTRS)

    Bucholtz, Anthongy; Hlavka, Dennis L.; McGill, Matthew J.; Schmidt, K. Sebastian; Pilewskie, Peter; Davis, Sean M.; Reid, Elizabeth A.; Walker, Annette L.

    2010-01-01

    We present the first direct measurements of the infrared and solar heating rates of a tropical subvisible cirrus (SVC) cloud sampled off the east coast of Nicaragua on 25 July 2007 by the NASA ER-2 aircraft during the Tropical Composition, Cloud and Climate Coupling Experiment (TC4). On this day a persistent thin cirrus layer, with mostly clear skies underneath, was detected in real time by the cloud lidar on the ER-2, and the aircraft was directed to profile down through the SVC. Measurements of the net broadband infrared irradiance and spectrally integrated solar irradiance above, below, and through the SVC are used to determine the infrared and solar heating rates of the cloud. The lidar measurements show that the variable SVC layer was located between approximately 13 and 15 km. Its midvisible optical depth varied from 0.01 to 0.10 with a mean of 0.034 +/- 0.033. Its depolarization ratio was approximately 0.4, indicative of ice clouds. From the divergence of the measured net irradiances the infrared heating rate of the SVC was determined to be approximately 2.50 - 3.24 K/d and the solar heating rate was found to be negligible. These values are consistent with previous indirect observations of other SVC and with model-generated heating rates of SVC with similar optical depths. This study illustrates the utility and potential of the profiling sampling strategy employed here. A more fully instrumented high-altitude aircraft that also included in situ cloud and aerosol probes would provide a comprehensive data set for characterizing both the radiative and microphysical properties of these ubiquitous tropical clouds

  12. Oxygen Ion Heat Rate within Alfvenic Turbulence in the Cusp

    NASA Technical Reports Server (NTRS)

    Coffey, Victoria N.; Singh, Nagendra; Chandler, Michael O.

    2009-01-01

    The role that the cleft/cusp has in ionosphere-magnetosphere coupling makes it a dynamic and important region. It is directly exposed to the solar wind, making it possible for the entry of electromagnetic energy and precipitating electrons and ions from dayside reconnection and other dayside events. It is also a significant source of ionospheric plasma, contributing largely to the mass loading of the magnetosphere with large fluxes of outflowing ions. Crossing the cusp/cleft near 5100 km, the Polar instruments observe the common correlation of downward Poynting flux, ion energization, soft electron precipitation, broadband extremely low-frequency (BB-ELF) emissions, and density depletions. The dominant power in the BB-ELF emissions is now identified to be from spatially broad, low frequency Alfv nic structures. For a cusp crossing, we determine using the Electric Field Investigation (EFI), that the electric and magnetic field fluctuations are Alfv nic and the electric field gradients satisfy the inequality for stochastic acceleration. With all the Polar 1996 horizontal crossings of the cusp, we determine the O+ heating rate using the Thermal Ion Dynamics Experiment (TIDE) and Plasma Wave Investigation (PWI). We then compare this heating rate to other heating rates assuming the electric field gradient criteria exceeds the limit for stochastic acceleration for the remaining crossings. The comparison suggests that a stochastic acceleration mechanism is operational and the heating is controlled by the transverse spatial scale of the Alfvenic waves.

  13. Oxygen Ion Heat Rate within Alfvenic Turbulence in the Cusp

    NASA Technical Reports Server (NTRS)

    Coffey, Victoria N.; Singh, Nagendra; Chandler, Michael O.

    2009-01-01

    The role that the cleft/cusp has in ionosphere-magnetosphere coupling makes it a dynamic and important region. It is directly exposed to the solar wind, making it possible for the entry of electromagnetic energy and precipitating electrons and ions from dayside reconnection and other dayside events. It is also a significant source of ionospheric plasma, contributing largely to the mass loading of the magnetosphere with large fluxes of outflowing ions. Crossing the cusp/cleft near 5100 km, the Polar instruments observe the common correlation of downward Poynting flux, ion energization, soft electron precipitation, broadband extremely low-frequency (BB-ELF) emissions, and density depletions. The dominant power in the BB-ELF emissions is now identified to be from spatially broad, low frequency Alfv nic structures. For a cusp crossing, we determine using the Electric Field Investigation (EFI), that the electric and magnetic field fluctuations are Alfv nic and the electric field gradients satisfy the inequality for stochastic acceleration. With all the Polar 1996 horizontal crossings of the cusp, we determine the O+ heating rate using the Thermal Ion Dynamics Experiment (TIDE) and Plasma Wave Investigation (PWI). We then compare this heating rate to other heating rates assuming the electric field gradient criteria exceeds the limit for stochastic acceleration for the remaining crossings. The comparison suggests that a stochastic acceleration mechanism is operational and the heating is controlled by the transverse spatial scale of the Alfvenic waves.

  14. Standby Rates for Combined Heat and Power Systems

    SciTech Connect

    Sedano, Richard; Selecky, James; Iverson, Kathryn; Al-Jabir, Ali

    2014-02-01

    Improvements in technology, low natural gas prices, and more flexible and positive attitudes in government and utilities are making distributed generation more viable. With more distributed generation, notably combined heat and power, comes an increase in the importance of standby rates, the cost of services utilities provide when customer generation is not operating or is insufficient to meet full load. This work looks at existing utility standby tariffs in five states. It uses these existing rates and terms to showcase practices that demonstrate a sound application of regulatory principles and ones that do not. The paper also addresses areas for improvement in standby rates.

  15. Numerical computations of Orbiter flow fields and heating rates

    NASA Technical Reports Server (NTRS)

    Goodrich, W. D.; Li, C. P.; Houston, C. K.; Chiu, P.; Olmedo, L.

    1976-01-01

    Numerical computations of flow fields around an analytical description of the Space Shuttle Orbiter windward surface, including the root of the wing leading edge, are presented to illustrate the sensitivity of these calculations to several flow field modeling assumptions. Results of parametric flow field and boundary layer computations using the axisymmetric analogue concept to obtain three-dimensional heating rates, in conjunction with exact three-dimensional inviscid floe field solutions and two-dimensional boundary layer analysis - show the sensitivity of boundary layer edge conditions and heating rates to considerations of the inviscid flow field entropy layer, equilibrium air versus chemically and vibrationally frozen flow, and nonsimilar terms in the boundary layer computations. A cursory comparison between flow field predictions obtained from these methods and current Orbiter design methods has established a benchmark for selecting and adjusting these and future design methodologies.

  16. An on-line expert system to improve heat rate

    SciTech Connect

    Shirley, R.S.; Forbes, H.; Nelson, R.F.

    1992-01-01

    A closed-loop expert system for supervisory control is described. The expert system, called ThermoPlus, is designed to help improve heat rates in a power plant, and is tested on a research, solar/fossil pilot plant. This paper describes the management of the project, including problem selection, controlling problem size, and designing the knowledge base. Initial results form running the expert system on line (but not closed-loop) are included.

  17. Numerical Study of a Three Dimensional Interaction between two bow Shock Waves and the Aerodynamic Heating on a Wedge Shaped Nose Cone

    NASA Astrophysics Data System (ADS)

    Wu, N.; Wang, J. H.; Shen, L.

    2017-03-01

    This paper presents a numerical investigation on the three-dimensional interaction between two bow shock waves in two environments, i.e. ground high-enthalpy wind tunnel test and real space flight, using Fluent 15.0. The first bow shock wave, also called induced shock wave, which is generated by the leading edge of a hypersonic vehicle. The other bow shock wave can be deemed objective shock wave, which is generated by the cowl clip of hypersonic inlet, and in this paper the inlet is represented by a wedge shaped nose cone. The interaction performances including flow field structures, aerodynamic pressure and heating are analyzed and compared between the ground test and the real space flight. Through the analysis and comparison, we can find the following important phenomena: 1) Three-dimensional complicated flow structures appear in both cases, but only in the real space flight condition, a local two-dimensional type IV interaction appears; 2) The heat flux and pressure in the interaction region are much larger than those in the no-interaction region in both cases, but the peak values of the heat flux and pressure in real space flight are smaller than those in ground test. 3) The interaction region on the objective surface are different in the two cases, and there is a peak value displacement of 3 mm along the stagnation line.

  18. Radiative heating rates during the Airborne Arctic Stratospheric Experiment

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.; Schoeberl, Mark R.; Lait, Leslie R.; Newman, Paul A.; Proffitt, Michael H.

    1990-01-01

    A radiative transfer model and observed temperature and ozone profiles are used to compute three-dimensional fields of heating rates for the Northern Hemisphere during 1989 Airborne Arctic Stratospheric Experiment. For a clear atmosphere, an average cooling of 0.2 to 0.4 K/day is computed in the regions of the ER-2 aircraft during flight days. Tropospheric clouds will increase the cooling by 0.1 to 0.2 K/day. These cooling rates are in good agreement with the diabatic cooling estimated from N2O data, Net heating rather than cooling is computed in the area of the ozone 'minihole' which had its maximum on 1/31/89 and 2/1/89 in the vicinity of the mission. On 1/31/89 the 50 and 30 mb net heating rates are 0.1 to 0.2 K/day for clear skies, and 0.05 to 0.1 K/day for cloudy skies.

  19. Cloud Properties and Radiative Heating Rates for TWP

    DOE Data Explorer

    Comstock, Jennifer

    2013-11-07

    A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote Sensor Retrieval Algorithm (CombRet) produces vertical profiles of liquid or ice water content (LWC or IWC), droplet effective radius (re), ice crystal generalized effective size (Dge), cloud phase, and cloud boundaries. The algorithm was compared with 3 other independent algorithms to help estimate the uncertainty in the cloud properties, fluxes, and heating rates (Comstock et al. 2013). The dataset is provided at 2 min temporal and 90 m vertical resolution. The current dataset is applied to time periods when the MMCR (Millimeter Cloud Radar) version of the ARSCL (Active Remotely-Sensed Cloud Locations) Value Added Product (VAP) is available. The MERGESONDE VAP is utilized where temperature and humidity profiles are required. Future additions to this dataset will utilize the new KAZR instrument and its associated VAPs.

  20. Radiative heating rates during the Airborne Arctic Stratospheric Experiment

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.; Schoeberl, Mark R.; Lait, Leslie R.; Newman, Paul A.; Proffitt, Michael H.

    1990-01-01

    A radiative transfer model and observed temperature and ozone profiles are used to compute three-dimensional fields of heating rates for the Northern Hemisphere during 1989 Airborne Arctic Stratospheric Experiment. For a clear atmosphere, an average cooling of 0.2 to 0.4 K/day is computed in the regions of the ER-2 aircraft during flight days. Tropospheric clouds will increase the cooling by 0.1 to 0.2 K/day. These cooling rates are in good agreement with the diabatic cooling estimated from N2O data, Net heating rather than cooling is computed in the area of the ozone 'minihole' which had its maximum on 1/31/89 and 2/1/89 in the vicinity of the mission. On 1/31/89 the 50 and 30 mb net heating rates are 0.1 to 0.2 K/day for clear skies, and 0.05 to 0.1 K/day for cloudy skies.

  1. The effects of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of a large-scale rotating turbine model. Volume 2: Heat transfer data tabulation. 15 percent axial spacing

    NASA Technical Reports Server (NTRS)

    Dring, R. P.; Blair, M. F.; Joslyn, H. D.

    1986-01-01

    A combined experimental and analytical program was conducted to examine the effects of inlet turbulence on airfoil heat transfer. The experimental portion of the study was conducted in a large-scale (approx 5X engine), ambient temperature, rotating turbine model configured in both single stage and stage-and-a-half arrangements. Heat transfer measurements were obtained using low-conductivity airfoils with miniature thermcouples welded to a thin, electrically heated surface skin. Heat transfer data were acquired for various combinations of low or high inlet turbulence intensity, flow coefficient, first-stator/rotor axial spacing, Reynolds number and relative circumferential position of the first and second stators. Aerodynamic measurements obtained as part of the program include distributions of the mean and fluctuating velocities at the turbine inlet and, for each airfoil row, midspan airfoil surface pressures and circumferential distributions of the downstream steady state pressures and fluctuating velocities. Analytical results include airfoil heat transfer predictions produced using existing 2-D boundary layer computation schemes and an examination of solutions of the unsteady boundary layer equations. The results are reported in four separate volumes, of which this is Volume 2: Heat Transfer Data Tabulation; 15 Percent Axial Spacing.

  2. Particle loading rates for HVAC filters, heat exchangers, and ducts.

    PubMed

    Waring, M S; Siegel, J A

    2008-06-01

    The rate at which airborne particulate matter deposits onto heating, ventilation, and air-conditioning (HVAC) components is important from both indoor air quality (IAQ) and energy perspectives. This modeling study predicts size-resolved particle mass loading rates for residential and commercial filters, heat exchangers (i.e. coils), and supply and return ducts. A parametric analysis evaluated the impact of different outdoor particle distributions, indoor emission sources, HVAC airflows, filtration efficiencies, coils, and duct system complexities. The median predicted residential and commercial loading rates were 2.97 and 130 g/m(2) month for the filter loading rates, 0.756 and 4.35 g/m(2) month for the coil loading rates, 0.0051 and 1.00 g/month for the supply duct loading rates, and 0.262 g/month for the commercial return duct loading rates. Loading rates are more dependent on outdoor particle distributions, indoor sources, HVAC operation strategy, and filtration than other considered parameters. The results presented herein, once validated, can be used to estimate filter changing and coil cleaning schedules, energy implications of filter and coil loading, and IAQ impacts associated with deposited particles. The results in this paper suggest important factors that lead to particle deposition on HVAC components in residential and commercial buildings. This knowledge informs the development and comparison of control strategies to limit particle deposition. The predicted mass loading rates allow for the assessment of pressure drop and indoor air quality consequences that result from particle mass loading onto HVAC system components.

  3. A Study of the Motion and Aerodynamic Heating of Missiles Entering the Earth's Atmosphere at High Supersonic Speeds

    NASA Technical Reports Server (NTRS)

    Allen, H. Julian; Eggers, A. J., Jr.

    1953-01-01

    A simplified analysis is made of the velocity and deceleration history of missiles entering the earth's atmosphere at high supersonic speeds. It is found that, in general, the gravity force is negligible compared to the aerodynamic drag force and, hence, that the trajectory is essentially a straight line. A constant drag coefficient and an exponential variation of density with altitude are assumed and generalized curves for the variation of missile speed and deceleration with altitude are obtained. A curious finding is that the maximum deceleration is independent of physical characteristics of a missile (e.g., mass, size, and drag coefficient) and is determined only by entry speed and flight-path angle, provided this deceleration occurs before impact. This provision is satisfied by missiles presently of more usual interest.

  4. Prediction of aerodynamic heating and pressures on Shuttle Entry Air Data System (SEADS) nose cap and comparison with STS-61C flight data

    NASA Technical Reports Server (NTRS)

    Ting, Paul C.; Rochelle, William C.; Curry, Donald M.

    1988-01-01

    Results are presented from predictions of aerothermodynamic heating rates, temperatures, and pressures on the surface of the Shuttle Entry Air Data System (SEADS) nosecap during Orbiter reentry. These results are compared with data obtained by the first actual flight of the SEADS system aboard STS-61C. The data also used to predict heating rates and surface temperatures for a hypothetical Transatlantic Abort Landing entry trajectory, whose analysis involved ascertaining the increases in heating rate as the airstream flowed across regions of the lower surface catalycity carbon/carbon composite to the higher surface catalycity columbium pressure ports.

  5. Influence of flow rate and heating power in effective thermal conductivity applied in borehole heat exchangers

    NASA Astrophysics Data System (ADS)

    Śliwa, T.; Sapińska-Śliwa, A.; Wiśniowski, R.; Piechówka, Z.; Krzemień, M.; Pycha, D.; Jaszczur, M.

    2016-09-01

    In borehole heat exchanging systems one of the most important parameters necessary to estimate its efficiency is the effective thermal conductivity. One of the methods for determining it is thermal response test. Such a test may be performed with respect to various parameters. The most important ones include flow rate and heating power. The article summarizes the results of TRT research in Palecznica village, Poland which was performed in boreholes located there in the already operating installation. It presents the established methodology. Also, there is an attempt to determine the relation between the mentioned parameters and the effective thermal conductivity. The research indicates the dependence of the conductivity with the test parameters.

  6. High speed civil transport aerodynamic optimization

    NASA Technical Reports Server (NTRS)

    Ryan, James S.

    1994-01-01

    This is a report of work in support of the Computational Aerosciences (CAS) element of the Federal HPCC program. Specifically, CFD and aerodynamic optimization are being performed on parallel computers. The long-range goal of this work is to facilitate teraflops-rate multidisciplinary optimization of aerospace vehicles. This year's work is targeted for application to the High Speed Civil Transport (HSCT), one of four CAS grand challenges identified in the HPCC FY 1995 Blue Book. This vehicle is to be a passenger aircraft, with the promise of cutting overseas flight time by more than half. To meet fuel economy, operational costs, environmental impact, noise production, and range requirements, improved design tools are required, and these tools must eventually integrate optimization, external aerodynamics, propulsion, structures, heat transfer, controls, and perhaps other disciplines. The fundamental goal of this project is to contribute to improved design tools for U.S. industry, and thus to the nation's economic competitiveness.

  7. Analysis of Water Recovery Rate from the Heat Melt Compactor

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Hegde, U.; Gokoglu, S.

    2013-01-01

    any remaining free water in the trash by evaporation. The temperature settings of the heated surfaces are usually kept above the saturation temperature of water but below the melting temperature of the plastic in the waste during this step to avoid any encapsulation of wet trash which would reduce the amount of recovered water by blocking the vapor escape. In this paper, we analyze the water recovery rate during Phase B where the trash is heated and water leaves the waste chamber as vapor, for operation of the HMC in reduced gravity. We pursue a quasi-one-dimensional model with and without sidewall heating to determine the water recovery rate and the trash drying time. The influences of the trash thermal properties, the amount of water loading, and the distribution of the water in the trash on the water recovery rates are determined.

  8. Effect of heating rate on highly heat-resistant spore-forming microorganisms.

    PubMed

    Gómez-Jódar, Isabel; Ros-Chumillas, María; Palop, Alfredo

    2016-03-01

    Highly heat-resistant spore-forming Bacillus cause nonsterility problems in canned food and reduce the shelf life of many processed foods. The aim of this research was to evaluate the thermal inactivation of Bacillus sporothermodurans IIC65, Bacillus subtilis IC9, and Geobacillus stearothermophilus T26 under isothermal and nonisothermal conditions. The data obtained showed that B. sporothermodurans and B. subtilis were more heat resistant than G. stearothermophilus. The survival curves of B. sporothermodurans and B. subtilis showed shoulders, while the survival curves of G. stearothermophilus showed tails. Under nonisothermal treatment, at heating rates of 1 and 20 ℃/min, time needed to completely inactivate G. stearothermophilus was shorter than that required for B. sporothermodurans and B. subtilis. In complex heat treatments (heating-holding-cooling), the survival curves of B. sporothermodurans and B. subtilis showed the same activation shoulders than those obtained under isothermal treatments and the activation shoulders were again absent in the case of G. stearothermophilus. Predictions fitted quite well the data obtained for B. sporothermodurans. In contrast, the data for B. subtilis showed half a log cycle more survival than expected and in the case of G. stearothermophilus, the survival curve obtained showed much higher inactivation than expected.

  9. Three-Dimensional Unsteady Simulation of Aerodynamics and Heat Transfer in a Modern High Pressure Turbine Stage

    NASA Technical Reports Server (NTRS)

    Shyam, Vikram; Ameri, Ali

    2009-01-01

    Unsteady 3-D RANS simulations have been performed on a highly loaded transonic turbine stage and results are compared to steady calculations as well as to experiment. A low Reynolds number k-epsilon turbulence model is employed to provide closure for the RANS system. A phase-lag boundary condition is used in the tangential direction. This allows the unsteady simulation to be performed by using only one blade from each of the two rows. The objective of this work is to study the effect of unsteadiness on rotor heat transfer and to glean any insight into unsteady flow physics. The role of the stator wake passing on the pressure distribution at the leading edge is also studied. The simulated heat transfer and pressure results agreed favorably with experiment. The time-averaged heat transfer predicted by the unsteady simulation is higher than the heat transfer predicted by the steady simulation everywhere except at the leading edge. The shock structure formed due to stator-rotor interaction was analyzed. Heat transfer and pressure at the hub and casing were also studied. Thermal segregation was observed that leads to the heat transfer patterns predicted by steady and unsteady simulations to be different.

  10. Dissociation rate of bromine diatomics in an argon heat bath

    NASA Technical Reports Server (NTRS)

    Razner, R.; Hopkins, D.

    1973-01-01

    The evolution of a collection of 300 K bromine diatomics embedded in a heat bath of argon atoms at 1800 K was studied by computer, and a dissociation-rate constant for the reaction Br2 + BR + Ar yields Br + Ar was determined. Previously published probability distributions for energy and angular momentum transfers in classical three-dimensional Br2-Ar collisions were used in conjunction with a newly developed Monte Carlo scheme for this purpose. Results are compared with experimental shock-tube data and the predictions of several other theoretical models. A departure from equilibrium is obtained which is significantly greater than that predicted by any of these other theories.

  11. Heat transfer rate within non-spherical thick grains

    NASA Astrophysics Data System (ADS)

    Huchet, Florian; Richard, Patrick; Joniot, Jules; Le Guen, Laurédan

    2017-06-01

    The prediction of the internal heat conduction into non-spherical thick grains constitutes a significant issue for physical modeling of a large variety of application involving convective exchanges between fluid and grains. In that context, the present paper deals with heat rate measurements of various sizes of particles, the thermal sensors being located at the interface fluid/grain and into the granular materials. Their shape is designed as cuboid in order to control the surface exchanges. In enclosed coneshaped apparatus, a sharp temperature gradient is ensured from a hot source releasing the air stream temperature equal to about 400°C. Two orientations of grain related to the air stream are considered: diagonally and straight arrangements. The thermal diffusivity of the grains and the Biot numbers are estimated from an analytical solution established for slab. The thermal kinetics evolution is correlated to the sample granular mass and its orientation dependency is demonstrated. Consequently, a generalized scaling law is proposed which is funded from the effective area of the heat transfer at the grain-scale, the dimensionless time being defined from the calculated diffusional coefficients.

  12. Heat generation rate measurement in a Li-ion cell at large C-rates through temperature and heat flux measurements

    NASA Astrophysics Data System (ADS)

    Drake, S. J.; Martin, M.; Wetz, D. A.; Ostanek, J. K.; Miller, S. P.; Heinzel, J. M.; Jain, A.

    2015-07-01

    Understanding the rate of heat generation in a Li-ion cell is critical for safety and performance of Li-ion cells and systems. Cell performance, cycle life, and system safety all depend on temperature distribution in the cell, which, in turn, depends on heat generation rate within the cell and on heat removal rate at the cell surface. Despite the existence of a number of theoretical models to predict heat generation rate, there is not much literature on experimental measurement at high C-rates. This paper reports measurement of heat generation rate from a Li-ion cell at high discharge rates, up to 9.6C, using measurements of cell temperature and surface heat flux. As opposed to calorimetry-based approaches, this method can be applied in situ to yield measurements of heat generation rate in laboratory or field use provided that at least one a priori test is performed to measure the temperature gradient within a cell in the same ambient condition. This method is based on simultaneous determination of heat stored and heat lost from the cell through heat flux and temperature measurements. A novel method is established for measurement of the internal temperature of the cell. Heat generation measurements are shown to agree with well-established theoretical models. The effect of actively cooling the cell is briefly discussed.

  13. Solar Flux Deposition And Heating Rates In Jupiter's Atmosphere

    NASA Astrophysics Data System (ADS)

    Perez-Hoyos, Santiago; Sánchez-Lavega, A.

    2009-09-01

    We discuss here the solar downward net flux in the 0.25 - 2.5 µm range in the atmosphere of Jupiter and the associated heating rates under a number of vertical cloud structure scenarios focusing in the effect of clouds and hazes. Our numerical model is based in the doubling-adding technique to solve the radiative transfer equation and it includes gas absorption by CH4, NH3 and H2, in addition to Rayleigh scattering by a mixture of H2 plus He. Four paradigmatic Jovian regions have been considered (hot-spots, belts, zones and Polar Regions). The hot-spots are the most transparent regions with downward net fluxes of 2.5±0.5 Wm-2 at the 6 bar level. The maximum solar heating is 0.04±0.01 K/day and occurs above 1 bar. Belts and zones characterization result in a maximum net downward flux of 0.5 Wm-2 at 2 bar and 0.015 Wm-2 at 6 bar. Heating is concentrated in the stratospheric and tropospheric hazes. Finally, Polar Regions are also explored and the results point to a considerable stratospheric heating of 0.04±0.02 K/day. In all, these calculations suggest that the role of the direct solar forcing in the Jovian atmospheric dynamics is limited to the upper 1 - 2 bar of the atmosphere except in the hot-spot areas. Acknowledgments: This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07.

  14. Coal plasticity at high heating rates and temperatures

    SciTech Connect

    Gerjarusak, S.; Peters, W.A.; Howard, J.B.

    1992-09-01

    Effects of pressure, temperature, and coal type on coal plasticity were investigated. Seven coals, from the Argonne premium sample bank ranging from lignite to low volatile bituminous, were studied. Elevated pressures, up to 10 atm of helium, did not affect coal plasticity, but reducing pressure from atmosphere to vacuum resulted in diminished plasticity, i.e. a shorter plastic period and a higher minimum apparent viscosity. It is hypothesized that high pressure inhibits mass transport of metaplast to tar vapors, but also favors metaplast repolymerization into coke and char. Higher holding temperature decreased the coal plastic period. It is hypothesized that higher temperature increases mass transport of liquid metaplast to tar vapors and metaplast repolymerization to coke and char. Heating rate had essentially no effect on the individual softening temperatures of five different plastic coals. Possible explanations are that, depending on coal type, metaplast generation, by chemical bond breaking or physical melting, or both, is not strongly affected by heating rate. In particular, for medium and low volatile bituminous cools, there is evidence that generation of the metaplast responsible for initial softening involves largely chemical bond breaking as opposed to physical melting.

  15. Broadband Heating Rate Profile Project (BBHRP) - SGP ripbe370mcfarlane

    DOE Data Explorer

    Riihimaki, Laura; Shippert, Timothy

    2014-11-05

    The objective of the ARM Broadband Heating Rate Profile (BBHRP) Project is to provide a structure for the comprehensive assessment of our ability to model atmospheric radiative transfer for all conditions. Required inputs to BBHRP include surface albedo and profiles of atmospheric state (temperature, humidity), gas concentrations, aerosol properties, and cloud properties. In the past year, the Radiatively Important Parameters Best Estimate (RIPBE) VAP was developed to combine all of the input properties needed for BBHRP into a single gridded input file. Additionally, an interface between the RIPBE input file and the RRTM was developed using the new ARM integrated software development environment (ISDE) and effort was put into developing quality control (qc) flags and provenance information on the BBHRP output files so that analysis of the output would be more straightforward. This new version of BBHRP, sgp1bbhrpripbeC1.c1, uses the RIPBE files as input to RRTM, and calculates broadband SW and LW fluxes and heating rates at 1-min resolution using the independent column approximation. The vertical resolution is 45 m in the lower and middle troposphere to match the input cloud properties, but is at coarser resolution in the upper atmosphere. Unlike previous versions, the vertical grid is the same for both clear-sky and cloudy-sky calculations.

  16. Broadband Heating Rate Profile Project (BBHRP) - SGP ripbe1mcfarlane

    DOE Data Explorer

    Riihimaki, Laura; Shippert, Timothy

    2014-11-05

    The objective of the ARM Broadband Heating Rate Profile (BBHRP) Project is to provide a structure for the comprehensive assessment of our ability to model atmospheric radiative transfer for all conditions. Required inputs to BBHRP include surface albedo and profiles of atmospheric state (temperature, humidity), gas concentrations, aerosol properties, and cloud properties. In the past year, the Radiatively Important Parameters Best Estimate (RIPBE) VAP was developed to combine all of the input properties needed for BBHRP into a single gridded input file. Additionally, an interface between the RIPBE input file and the RRTM was developed using the new ARM integrated software development environment (ISDE) and effort was put into developing quality control (qc) flags and provenance information on the BBHRP output files so that analysis of the output would be more straightforward. This new version of BBHRP, sgp1bbhrpripbeC1.c1, uses the RIPBE files as input to RRTM, and calculates broadband SW and LW fluxes and heating rates at 1-min resolution using the independent column approximation. The vertical resolution is 45 m in the lower and middle troposphere to match the input cloud properties, but is at coarser resolution in the upper atmosphere. Unlike previous versions, the vertical grid is the same for both clear-sky and cloudy-sky calculations.

  17. NASP aerodynamics

    NASA Technical Reports Server (NTRS)

    Whitehead, Allen H., Jr.

    1989-01-01

    This paper discusses the critical aerodynamic technologies needed to support the development of a class of aircraft represented by the National Aero-Space Plane (NASP). The air-breathing, single-stage-to-orbit mission presents a severe challenge to all of the aeronautical disciplines and demands an extension of the state-of-the-art in each technology area. While the largest risk areas are probably advanced materials and the development of the scramjet engine, there remains a host of design issues and technology problems in aerodynamics, aerothermodynamics, and propulsion integration. The paper presents an overview of the most significant propulsion integration problems, and defines the most critical fluid flow phenomena that must be evaluated, defined, and predicted for the class of aircraft represented by the Aero-Space Plane.

  18. Effect of dynamic and thermal prehistory on aerodynamic characteristics and heat transfer behind a sudden expansion in a round tube

    NASA Astrophysics Data System (ADS)

    Terekhov, V. I.; Bogatko, T. V.

    2017-03-01

    The results of a numerical study of the influence of the thicknesses of dynamic and thermal boundary layers on turbulent separation and heat transfer in a tube with sudden expansion are presented. The first part of this work studies the influence of the thickness of the dynamic boundary layer, which was varied by changing the length of the stabilization area within the maximal extent possible: from zero to half of the tube diameter. In the second part of the study, the flow before separation was hydrodynamically stabilized and the thermal layer before the expansion could simultaneously change its thickness from 0 to D1/2. The Reynolds number was varied in the range of {Re}_{{{{D}}1 }} = 6.7 \\cdot 103 {{to}} 1.33 \\cdot 105, and the degree of tube expansion remained constant at ER = ( D 2/ D 1)2 = 1.78. A significant effect of the thickness of the separated boundary layer on both dynamic and thermal characteristics of the flow is shown. In particular, it was found out that with an increase in the thickness of the boundary layer the recirculation zone increases and the maximal Nusselt number decreases. It was determined that the growth of the heat layer thickness does not affect the hydrodynamic characteristics of the flow after separation but does lead to a reduction of heat transfer intensity in the separation area and removal of the coordinates of maximal heat transfer from the point of tube expansion. The generalizing dependence for the maximal Nusselt number at various thermal layer thicknesses is given. Comparison with experimental data confirmed the main trends in the behavior of heat and mass transfer processes in separated flows behind a step with different thermal prehistories.

  19. Effect of the rate of temperature increase on water quality during heating in electromagnetic- and gas-heated pans.

    PubMed

    Hiratsuka, Hiroshi; Sasaki, Ken

    2004-04-01

    More rapid increases in the pH value and hardness during electromagnetic heating of a pan of water were observed than when the pan was heated by LNG or LPG. The water quality changed universally in several tap water samples across Japan. This quality change was closely correlated with the rate of temperature increase, irrespective of heating by electromagnetic induction, LNG or LPG.

  20. Heat transfer rate distributions on McDonnell-Douglas booster determined by phase change technique for nominal Mach number of 8

    NASA Technical Reports Server (NTRS)

    Matthews, R. K.; Martindale, W. R.; Warmbrod, J. D.

    1972-01-01

    The results of a wind tunnel test program to determine aerodynamic heat transfer distributions on the McDonnell Douglas Booster configuration are presented. Heat-transfer rates were determined by the phase-change paint technique on 0.009-scale Stycast models using Tempilaq as the surface temperature indicator. The nominal test conditions were; Mach 8, length Reynolds numbers 5 million and 7.3 million, and angles of attack of 40, 50, and 60 deg. At the higher Reynolds number, data were obtained with and without boundary layer trips. Model details, test conditions, and reduced heat-transfer data are presented. Data reduction of the phase-change paint photographs was performed by utilizing a new technique which is described.

  1. Heat transfer rate distribution on North American Rockwell delta wing orbiter determined by phase change paint technique at a Mach number of 8, volume 1

    NASA Technical Reports Server (NTRS)

    Matthews, R. K.; Martindale, W. R.; Warmbrod, J. D.

    1972-01-01

    The results of a wind tunnel test program to determine aerodynamic heat transfer distributions on an orbiter configuration are presented. Heat-transfer rates were determined by the phase change paint technique on 0.013-scale Stycast models using Tempilaq as the surface temperature indicator. The nominal test conditions were; Mach 8, length Reynolds numbers of 6.0 x 1 million and 8.9 x 1 million, and angles of attack from 10 to 50 deg in 10-deg increments. At the higher Reynolds number, data were obtained with and without boundary layer trips. Model details, test conditions, and reduced heat-transfer data are presented. Data reduction of the phase-change paint photographs was performed by utilizing a new technique which is described in the data presentation section.

  2. Rate of Heat Transfer from Finned Metal Surfaces

    NASA Technical Reports Server (NTRS)

    Taylor, G Fayette; Rehbock, A

    1930-01-01

    The object was to evaluate the factors which control the rate of heat transfer to a moving current of air from finned metal surfaces similar to those used on aircraft engine cylinders. The object was to establish data which will enable the finning of cooling surfaces to be designed to suit the particular needs of any specific application. Most of the work was done on flat copper specimens 6 inches square, upon which were mounted copper fins with spacings varying from 1/2 inch to 1/12 inch. All fins were 1 inch deep, 6 inches long, and .020 inch thick. The results of the investigation are given in the form of curves included here. In general, it was found that for specimens of this kind, the effectiveness of a given fin does not decrease very rapidly until its distance from adjacent fins has been reduced to 1/9 or 1/10 of an inch. A formula for the heat transfer from a flat surface without fins was developed, and an approximate formula for the finned specimens is suggested.

  3. Aerodynamics and Heat Transfer Studies of Parameters Specific to the IGCC-Requirements: Endwall Contouring, Leading Edge and Blade Tip Ejection under Rotating Turbine Conditions

    SciTech Connect

    Schobeiri, Meinhard; Han, Je-Chin

    2014-09-30

    This report deals with the specific aerodynamics and heat transfer problematic inherent to high pressure (HP) turbine sections of IGCC-gas turbines. Issues of primary relevance to a turbine stage operating in an IGCC-environment are: (1) decreasing the strength of the secondary flow vortices at the hub and tip regions to reduce (a), the secondary flow losses and (b), the potential for end wall deposition, erosion and corrosion due to secondary flow driven migration of gas flow particles to the hub and tip regions, (2) providing a robust film cooling technology at the hub and that sustains high cooling effectiveness less sensitive to deposition, (3) investigating the impact of blade tip geometry on film cooling effectiveness. The document includes numerical and experimental investigations of above issues. The experimental investigations were performed in the three-stage multi-purpose turbine research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL), Texas A&M University. For the numerical investigations a commercial Navier-Stokes solver was utilized.

  4. 40 CFR 75.83 - Calculation of Hg mass emissions and heat input rate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... heat input rate. 75.83 Section 75.83 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Calculation of Hg mass emissions and heat input rate. The owner or operator shall calculate Hg mass emissions and heat input rate in accordance with the procedures in sections 9.1 through 9.3 of appendix F to...

  5. Measurements of Aerodynamic Heat Transfer and Boundary-Layer Transition on a 15 deg. Cone in Free Flight at Supersonic Mach Numbers up to 5.2

    NASA Technical Reports Server (NTRS)

    Rumsey, Charles B.; Lee, Dorothy B.

    1961-01-01

    Measurements of aerodynamic heat transfer have been made at several stations on the 15 deg total-angle conical nose of a rocket-propelled model in free flight at Mach numbers up to 5.2. Data are presented for a range of local Mach number just outside the boundary layer from 1.40 to 4.65 and a range of local Reynolds number from 3.8 x 10(exp 6) to 46.5 x 10(exp 6), based on length from the nose tip to a measurement station. Laminar, transitional, and turbulent heat-transfer coefficients were measured. The laminar data were in agreement with laminar theory for cones, and the turbulent data agreed well with turbulent theory for cones using Reynolds number based on length from the nose tip. At a nearly constant ratio of wall to local static temperature of 1.2 the Reynolds number of transition increased from 14 x 10(exp 6) to 30 x 10(exp 6) as Mach number increased from 1.4 to 2.9 and then decreased to 17 x 10(exp 6) as Mach number increased to 3.7. At Mach numbers near 3.5, transition Reynolds numbers appeared to be independent of skin temperature at skin temperatures very cold with respect to adiabatic wall temperature. The transition Reynolds number was 17.7 x 10(exp 6) at a condition of Mach number and ratio of wall to local static temperature near that for which three-dimensional disturbance theory has been evaluated and has predicted laminar boundary-layer stability to very high Reynolds numbers (approximately 10(exp 12)).

  6. The Optimum Plate to Plate Spacing for Maximum Heat Transfer Rate from a Flat Plate Type Heat Exchanger

    NASA Astrophysics Data System (ADS)

    Ambarita, Himsar; Kishinami, Koki; Daimaruya, Mashashi; Tokura, Ikuo; Kawai, Hideki; Suzuki, Jun; Kobiyama, Mashayosi; Ginting, Armansyah

    The present paper is a study on the optimum plate to plate spacing for maximum heat transfer rate from a flat plate type heat exchanger. The heat exchanger consists of a number of parallel flat plates. The working fluids are flowed at the same operational conditions, either fixed pressure head or fixed fan power input. Parallel and counter flow directions of the working fluids were considered. While the volume of the heat exchanger is kept constant, plate number was varied. Hence, the spacing between plates as well as heat transfer rate will vary and there exists a maximum heat transfer rate. The objective of this paper is to seek the optimum plate to plate spacing for maximum heat transfer rate. In order to solve the problem, analytical and numerical solutions have been carried out. In the analytical solution, the correlations of the optimum plate to plate spacing as a function of the non-dimensional parameters were developed. Furthermore, the numerical simulation is carried out to evaluate the correlations. The results show that the optimum plate to plate spacing for a counter flow heat exchanger is smaller than parallel flow ones. On the other hand, the maximum heat transfer rate for a counter flow heat exchanger is bigger than parallel flow ones.

  7. An Analysis of Exact and Approximate Equations for the Temperature Distribution in an Insulated Thick Skin Subjected to Aerodynamic Heating

    NASA Technical Reports Server (NTRS)

    Harris, Robert S., Jr.; Davidson, John R.

    1961-01-01

    The problem of calculating the temperature distribution in an insulated slab is investigated. Exact and approximate solutions are obtained, and the results are compared to determine the ranges of applicability of the approximations. The approximations are found to be within 5 percent of the exact solution when the ratio of the thermal capacitance of the metal to that of the insulation and the ratio of the conductance of the metal to that of the insulation are sufficiently large. The roots of the characteristic equation of the exact solution are generally applicable to the two-slab heat-transfer problem and are tabulated up to the first nine roots.

  8. PREFACE: Aerodynamic sound Aerodynamic sound

    NASA Astrophysics Data System (ADS)

    Akishita, Sadao

    2010-02-01

    The modern theory of aerodynamic sound originates from Lighthill's two papers in 1952 and 1954, as is well known. I have heard that Lighthill was motivated in writing the papers by the jet-noise emitted by the newly commercialized jet-engined airplanes at that time. The technology of aerodynamic sound is destined for environmental problems. Therefore the theory should always be applied to newly emerged public nuisances. This issue of Fluid Dynamics Research (FDR) reflects problems of environmental sound in present Japanese technology. The Japanese community studying aerodynamic sound has held an annual symposium since 29 years ago when the late Professor S Kotake and Professor S Kaji of Teikyo University organized the symposium. Most of the Japanese authors in this issue are members of the annual symposium. I should note the contribution of the two professors cited above in establishing the Japanese community of aerodynamic sound research. It is my pleasure to present the publication in this issue of ten papers discussed at the annual symposium. I would like to express many thanks to the Editorial Board of FDR for giving us the chance to contribute these papers. We have a review paper by T Suzuki on the study of jet noise, which continues to be important nowadays, and is expected to reform the theoretical model of generating mechanisms. Professor M S Howe and R S McGowan contribute an analytical paper, a valuable study in today's fluid dynamics research. They apply hydrodynamics to solve the compressible flow generated in the vocal cords of the human body. Experimental study continues to be the main methodology in aerodynamic sound, and it is expected to explore new horizons. H Fujita's study on the Aeolian tone provides a new viewpoint on major, longstanding sound problems. The paper by M Nishimura and T Goto on textile fabrics describes new technology for the effective reduction of bluff-body noise. The paper by T Sueki et al also reports new technology for the

  9. Missile Aerodynamics

    DTIC Science & Technology

    1979-02-01

    4 HIGH-ANGLE-OF-ATTACK MISSILE AERODYNAMICS by A.B.Wardlaw, Jr ECOULEMENTS DE CU LOT par i.Delery et M.Sirieix 6 THE CONTROL OF GUIDED WEAPONS by...in Figure 3, or the bomblet shown in Figure 4 . It must be conceded that the weapon aero- dynamicist does not usually have to concern himself with the...conveniently divided into the four categories shown in Figure 5: I Unguided and unpropelled. 2 Unguided and propelled. 3 Guided and unpropelled. 4 Guided

  10. Chaff Aerodynamics

    DTIC Science & Technology

    1975-11-01

    diameters. Test Numbers 416 - 421 were for the purpose of evaluating the effect of geometric and mass asymmetry on the flight behavior of test articles 12...0 C3 = oe 10Ŕ V-0 1 E0!.. .00 00 . N. CL) u 8;; G Z C,, C5 0ý 1 ýC iC LAJI4- _ _ _ _ _ _ _ _ _ _ _ _ _ NNU-’ x ft..00 *E00 g tOO n.Ot4 N.SE’.C.a- CP ...1973. 36. Counihan, J., "Aerodynamics of Atmospheric Shear Flow," AGARD Conference Proceedings, No. 48, Hartford House, 1970. 37. Luers, J. K., "A

  11. Effect of Flow Rate on In Vitro Aerodynamic Performance of NEXThaler® in Comparison with Diskus® and Turbohaler® Dry Powder Inhalers

    PubMed Central

    Buttini, Francesca; Brambilla, Gaetano; Copelli, Diego; Sisti, Viviana; Balducci, Anna Giulia; Bettini, Ruggero; Pasquali, Irene

    2016-01-01

    Abstract Background: European and United States Pharmacopoeia compendial procedures for assessing the in vitro emitted dose and aerodynamic size distribution of a dry powder inhaler require that 4.0 L of air at a pressure drop of 4 kPa be drawn through the inhaler. However, the product performance should be investigated using conditions more representative of what is achievable by the patient population. This work compares the delivered dose and the drug deposition profile at different flow rates (30, 40, 60, and 90 L/min) of Foster NEXThaler® (beclomethasone dipropionate/formoterol fumarate), Seretide® Diskus® (fluticasone propionate/salmeterol xinafoate), and Symbicort® Turbohaler® (budesonide/formoterol fumarate). Methods: The delivered dose uniformity was tested using a dose unit sampling apparatus (DUSA) at inhalation volumes either 2.0 or 4.0 L and flow rates 30, 40, 60, or 90 L/min. The aerodynamic assessment was carried out using a Next Generation Impactor by discharging each inhaler at 30, 40, 60, or 90 L/min for a time sufficient to obtain an air volume of 4 L. Results: Foster® NEXThaler® and Seretide® Diskus® showed a consistent dose delivery for both the drugs included in the formulation, independently of the applied flow rate. Contrary, Symbicort® Turbohaler® showed a high decrease of the emitted dose for both budesonide and formoterol fumarate when the device was operated at airflow rate lower that 60 L/min. The aerosolizing performance of NEXThaler® and Diskus® was unaffected by the flow rate applied. Turbohaler® proved to be the inhaler most sensitive to changes in flow rate in terms of fine particle fraction (FPF) for both components. Among the combinations tested, Foster NEXThaler® was the only one capable to deliver around 50% of extra-fine particles relative to delivered dose. Conclusions: NEXThaler® and Diskus® were substantially unaffected by flow rate through the inhaler in terms of both delivered dose and

  12. Evaluation of sensible heat flux, latent heat flux, and effective aerodynamic roughness at the land surface from a combination of satellite and in-situ data

    NASA Technical Reports Server (NTRS)

    Diak, George R.

    1990-01-01

    A simple method is presented for using the daytime rise of the PBL height, combined with coincident satellite skin temperature measurements, to evaluate sensible heating and the effective surface roughness for heat transfer at synoptic locations. Multiple runs of a combination surface layer-mixed layer model are made in the central U.S., varying the values of surface moisture and roughness length around climatological means, and initializing the model with a set of atmospheric conditions from the synoptic report. The results, shown in figures and tables, are quite reasonable and spatially coherent, and depict well the sharp change in surface moisture and roughness which is known to take place across the central U.S.

  13. Dissolution and Precipitation Behaviour during Continuous Heating of Al–Mg–Si Alloys in a Wide Range of Heating Rates

    PubMed Central

    Osten, Julia; Milkereit, Benjamin; Schick, Christoph; Kessler, Olaf

    2015-01-01

    In the present study, the dissolution and precipitation behaviour of four different aluminium alloys (EN AW-6005A, EN AW-6082, EN AW-6016, and EN AW-6181) in four different initial heat treatment conditions (T4, T6, overaged, and soft annealed) was investigated during heating in a wide dynamic range. Differential scanning calorimetry (DSC) was used to record heating curves between 20 and 600 °C. Heating rates were studied from 0.01 K/s to 5 K/s. We paid particular attention to control baseline stability, generating flat baselines and allowing accurate quantitative evaluation of the resulting DSC curves. As the heating rate increases, the individual dissolution and precipitation reactions shift to higher temperatures. The reactions during heating are significantly superimposed and partially run simultaneously. In addition, precipitation and dissolution reactions are increasingly suppressed as the heating rate increases, whereby exothermic precipitation reactions are suppressed earlier than endothermic dissolution reactions. Integrating the heating curves allowed the enthalpy levels of the different initial microstructural conditions to be quantified. Referring to time–temperature–austenitisation diagrams for steels, continuous heating dissolution diagrams for aluminium alloys were constructed to summarise the results in graphical form. These diagrams may support process optimisation in heat treatment shops.

  14. Heat transfer intensification by increasing vapor flow rate in flat heat pipes

    NASA Astrophysics Data System (ADS)

    Sprinceana, Silviu; Mihai, Ioan; Beniuga, Marius; Suciu, Cornel

    2015-02-01

    Flat heat pipes have various technical applications, one of the most important being the cooling of electronic components[9]. Their continuous development is due to the fact that these devices permit heat transfer without external energetic contribution. The practical exploitation of flat heat pipes however is limited by the fact that dissipated power can only reach a few hundred watts. The present paper aims to advance a new method for the intensification of convective heat transfer. A centrifugal mini impeller, driven by a turntable which incorporates four permanent magnets was designed. These magnets are put in motion by another rotor, which in its turn includes two permanent magnets and is driven by a mini electrical motor. Rotation of the centrifugal blades generates speed and pressure increase of the cooling agent brought to vapor state within the flat micro heat pipe. It's well known that the liquid suffers biphasic transformations during heat transfer inside the heat pipe. Over the hotspot (the heat source being the electronic component) generated at one end of the heat pipe, convective heat transfer occurs, leading to sudden vaporization of the liquid. Pressures generated by newly formed vapors push them towards the opposite end of the flat heat pipe, where a finned mini heat sink is usually placed. The mini-heat exchanger is air-cooled, thus creating a cold spot, where vapors condensate. The proposed method contributes to vapor flow intensification by increasing their transport speed and thus leading to more intense cooling of the heat pipe.

  15. An algorithm for the kinetics of tire pyrolysis under different heating rates.

    PubMed

    Quek, Augustine; Balasubramanian, Rajashekhar

    2009-07-15

    Tires exhibit different kinetic behaviors when pyrolyzed under different heating rates. A new algorithm has been developed to investigate pyrolysis behavior of scrap tires. The algorithm includes heat and mass transfer equations to account for the different extents of thermal lag as the tire is heated at different heating rates. The algorithm uses an iterative approach to fit model equations to experimental data to obtain quantitative values of kinetic parameters. These parameters describe the pyrolysis process well, with good agreement (r(2)>0.96) between the model and experimental data when the model is applied to three different brands of automobile tires heated under five different heating rates in a pure nitrogen atmosphere. The model agrees with other researchers' results that frequencies factors increased and time constants decreased with increasing heating rates. The model also shows the change in the behavior of individual tire components when the heating rates are increased above 30 K min(-1). This result indicates that heating rates, rather than temperature, can significantly affect pyrolysis reactions. This algorithm is simple in structure and yet accurate in describing tire pyrolysis under a wide range of heating rates (10-50 K min(-1)). It improves our understanding of the tire pyrolysis process by showing the relationship between the heating rate and the many components in a tire that depolymerize as parallel reactions.

  16. Heat storage rate and acute fatigue in rats.

    PubMed

    Rodrigues, L O C; Oliveira, A; Lima, N R V; Machado-Moreira, C A

    2003-01-01

    Thermal environmental stress can anticipate acute fatigue during exercise at a fixed intensity (%VO2max). Controversy exists about whether this anticipation is caused by the absolute internal temperature (Tint, degrees C), by the heat storage rate (HSR, cal/min) or by both mechanisms. The aim of the present study was to study acute fatigue (total exercise time, TET) during thermal stress by determining Tint and HSR from abdominal temperature. Thermal environmental stress was controlled in an environmental chamber and determined as wet bulb globe temperature ( degrees C), with three environmental temperatures being studied: cold (18 degrees C), thermoneutral (23.1 degrees C) or hot (29.4 degrees C). Six untrained male Wistar rats weighing 260-360 g were used. The animals were submitted to exercise at the same time of day in the three environments and at two treadmill velocities (21 and 24 m/min) until exhaustion. After implantation of a temperature sensor and treadmill adaptation, the animals were submitted to a Latin square experimental design using a 2 x 3 factorial scheme (velocity and environment), with the level of significance set at P<0.05. The results showed that the higher the velocity and the ambient temperature, the lower was the TET, with these two factors being independent. This result indicated that fatigue was independently affected by both the increase in exercise intensity and the thermal environmental stress. Fatigue developed at different Tint and HSR showed the best inverse relationship with TET. We conclude that HSR was the main anticipating factor of fatigue.

  17. Influence of tonicity and chloramphenicol on hyperthermic cytotoxicity and cell permeability under various heating rates.

    PubMed

    Morozov, I I; Petin, V G; Dubovick, B V

    1997-01-01

    The cell lethality and permeability induced in Escherichia coli B/r, Escherichia coli Bs-1 and Zygosaccharomyces bailii cells by high temperature (52 degrees C) after heating at different rates (mean s 0.015, 0.25 and 1.50 degrees C per s) and in media of different tonicity and content (isotonic YEP broth versus 0.01 M phosphate buffer, pH 7.0 containing different concentrations of NaCl) and with versus without chloramphenicol (10 micrograms/ml) have been investigated. Hyperthermic treatment in YEP broth of isotonic 0.01 M phosphate buffer resulted in markedly reduced cytotoxicity with decreasing heat rate. The heating rate effect was larger when the cells were treated in YEP broth. Chloramphenicol, which is known to inhibit expression of heat shock proteins in bacteria, did not affect the viability of cells or the development of thermotolerance in cells heated at different heating rates in isotonic phosphate buffer but prevented the development of an additional degree of thermotolerance in cells heated slowly in YEP broth. In contrast, the differential effect of heating rate on cytotoxicity and cell permeability was not demonstrated when cells were heated in hypertonic solution (1M NaCl in phosphate buffer, pH 7.0). It is proposed that heat destabilization of the osmotic cell homeostasis, which is more profound after rapid heating, plays a major part in heat induced cellular lethality.

  18. An examination of heat rate improvements due to waste heat integration in an oxycombustion pulverized coal power plant

    NASA Astrophysics Data System (ADS)

    Charles, Joshua M.

    Oxyfuel, or oxycombustion, technology has been proposed as one carbon capture technology for coal-fired power plants. An oxycombustion plant would fire coal in an oxidizer consisting primarily of CO2, oxygen, and water vapor. Flue gas with high CO2 concentrations is produced and can be compressed for sequestration. Since this compression generates large amounts of heat, it was theorized that this heat could be utilized elsewhere in the plant. Process models of the oxycombustion boiler, steam cycle, and compressors were created in ASPEN Plus and Excel to test this hypothesis. Using these models, heat from compression stages was integrated to the flue gas recirculation heater, feedwater heaters, and to a fluidized bed coal dryer. All possible combinations of these heat sinks were examined, with improvements in coal flow rate, Qcoal, net power, and unit heat rate being noted. These improvements would help offset the large efficiency impacts inherent to oxycombustion technology.

  19. A Simple Rate Law Experiment Using a Custom-Built Isothermal Heat Conduction Calorimeter

    ERIC Educational Resources Information Center

    Wadso, Lars; Li, Xi.

    2008-01-01

    Most processes (whether physical, chemical, or biological) produce or consume heat: measuring thermal power (the heat production rate) is therefore a typical method of studying processes. Here we describe the design of a simple isothermal heat conduction calorimeter built for use in teaching; we also provide an example of its use in simultaneously…

  20. A Simple Rate Law Experiment Using a Custom-Built Isothermal Heat Conduction Calorimeter

    ERIC Educational Resources Information Center

    Wadso, Lars; Li, Xi.

    2008-01-01

    Most processes (whether physical, chemical, or biological) produce or consume heat: measuring thermal power (the heat production rate) is therefore a typical method of studying processes. Here we describe the design of a simple isothermal heat conduction calorimeter built for use in teaching; we also provide an example of its use in simultaneously…

  1. A Method for Determining the Rate of Heat Transfer from a Wing or Streamline Body

    NASA Technical Reports Server (NTRS)

    Frick, Charles W; Mccullough, George B

    1945-01-01

    A method for calculating the rate of heat transfer from the surface of an airfoil or streamline body is presented. A comparison with the results of an experimental investigation indicates that the accuracy of the method is good. This method may be used to calculate the heat supply necessary for heat de-icing or in ascertaining the heat loss from the fuselage of an aircraft operating at great altitude. To illustrate the method, the total rate of heat transfer from an airfoil is calculated and compared with the experimental results.

  2. Digestive state influences the heart rate hysteresis and rates of heat exchange in the varanid lizard Varanus rosenbergi.

    PubMed

    Clark, T D; Butler, P J; Frappell, P B

    2005-06-01

    To maximize the period where body temperature (Tb) exceeds ambient temperature (Ta), many reptiles have been reported to regulate heart rate (fH) and peripheral blood flow so that the rate of heat gain in a warming environment occurs more rapidly than the rate of heat loss in a cooling environment. It may be hypothesized that the rate of cooling, particularly at relatively cool Tbs, would be further reduced during postprandial periods when specific dynamic action (SDA) increases endogenous heat production (i.e. the heat increment of feeding). Furthermore, it may also be hypothesized that the increased perfusion of the gastrointestinal organs that occurs during digestion may limit peripheral blood flow and thus compromise the rate of heating. Finally, if the changes in fh are solely for the purpose of thermoregulation, there should be no associated changes in energy demand and, consequently, no hysteresis in the rate of oxygen consumption (V(O2)). To test these hypotheses, seven individual Varanus rosenbergi were heated and cooled between 19 degrees C and 35 degrees C following at least 8 days fasting and then approximately 25 h after consumption of a meal (mean 10% of fasted body mass). For a given Tb between the range of 19-35 degrees C, fh of fasting lizards was higher during heating than during cooling. Postprandial lizards also displayed a hysteresis in fh, although the magnitude was reduced in comparison with that of fasting lizards as a result of a higher fh during cooling in postprandial animals. Both for fasting and postprandial lizards, there was no hysteresis in V(O2) at any Tb throughout the range although, as a result of SDA, postprandial animals displayed a significantly higher V(O2) than fasting animals both during heating and during cooling at Tbs above 24 degrees C. The values of fh during heating at a given Tb were the same for fasting and postprandial animals, which, in combination with a slower rate of heating in postprandial animals, suggests

  3. Dielectric properties and heating rate of broccoli powder as related to radio-frequency heating

    USDA-ARS?s Scientific Manuscript database

    Recently, Salmonella contamination was identified in low-moisture foods including dried vegetable powder. Radio Frequency (RF) dielectric heating is a potential alternative pasteurization method with short heating time. Dielectric properties of broccoli powder with 6.9, 9.1, 12.2, and 14.9%, w. b....

  4. Convective Heat Transfer Scaling of Ignition Delay and Burning Rate with Heat Flux and Stretch Rate in the Equivalent Low Stretch Apparatus

    NASA Technical Reports Server (NTRS)

    Olson, Sandra

    2011-01-01

    To better evaluate the buoyant contributions to the convective cooling (or heating) inherent in normal-gravity material flammability test methods, we derive a convective heat transfer correlation that can be used to account for the forced convective stretch effects on the net radiant heat flux for both ignition delay time and burning rate. The Equivalent Low Stretch Apparatus (ELSA) uses an inverted cone heater to minimize buoyant effects while at the same time providing a forced stagnation flow on the sample, which ignites and burns as a ceiling fire. Ignition delay and burning rate data is correlated with incident heat flux and convective heat transfer and compared to results from other test methods and fuel geometries using similarity to determine the equivalent stretch rates and thus convective cooling (or heating) rates for those geometries. With this correlation methodology, buoyant effects inherent in normal gravity material flammability test methods can be estimated, to better apply the test results to low stretch environments relevant to spacecraft material selection.

  5. Calorimeter measures high nuclear heating rates and their gradients across a reactor test hole

    NASA Technical Reports Server (NTRS)

    Burwell, D.; Coombe, J. R.; Mc Bride, J.

    1970-01-01

    Pedestal-type calorimeter measures gamma-ray heating rates from 0.5 to 7.0 watts per gram of aluminum. Nuclear heating rate is a function of cylinder temperature change, measured by four chromel-alumel thermocouples attached to the calorimeter, and known thermoconductivity of the tested material.

  6. Space shuttle: Heat transfer rate distributions on McDonnell-Douglas delta wing orbiter determined by phase-change paint technique for nominal Mach number of 8

    NASA Technical Reports Server (NTRS)

    Matthews, R. K.; Martindale, W. R.; Warmbrod, J. D.

    1972-01-01

    The results are reported of the phase-change paint tests conducted at Mach 8, to determine the aerodynamic heat transfer distributions on the McDonnell Douglas delta wing orbiter. Model details, test conditions, and reduced heat transfer data are presented.

  7. Heating rate effect on char yield from cotton, poly(ethylene terephthalate) and blend fabrics.

    PubMed

    Alongi, Jenny; Camino, Giovanni; Malucelli, Giulio

    2013-02-15

    Thermal behaviour of polymers is generally assessed by relatively low heating rate, such as in thermogravimetry (typically at 10 °C/min), which leads to progressive decomposition of chemical bonds with increasing dissociation energy under thermodynamic control. However, polymer materials may be accidentally exposed to high heating rates such as in a fire, when their thermal decomposition, occurring through competing paths, becomes kinetically controlled and may lead to heating rate dependence of their degradation mechanisms and products. In the present paper, thermogravimetry at 100, 200 and 300 °C/min heating rates has been carried out on cotton, poly(ethylene terephthalate) and their blend fabrics, which decompose with partial charring. The obtained results show that the char, produced by thermal and thermo-oxidative degradation of such polymer materials, is affected by the heating rate essentially in terms of thermal stability and yield, depending on the type of polymer and the absence or presence of air oxygen.

  8. Influence of heating rate and temperature on austenite grain size during reheating steel

    NASA Astrophysics Data System (ADS)

    Napitupulu, Richard A. M.

    2017-09-01

    Controlling the final microstructure is one effective way to get HSLA steel with good mechanical properties. The structure of the desired item on the final microstructure depends on the initial grain size formed during the initial heating process, where to get super fine ferrite grains, it should form the initial austenite grain smooth during the heating process. Austenite grain size at the beginning of the heating process is important in order to obtain the size of the final microstructure that provides maximum mechanical properties. In this study, HSLA steel reheated to a temperature of 960°C, 1060°C and 1120°C with holding time variation of 10, 30 and 60 minutes at a heating rate of 5°C/minute, 7.5°C/minute and 10°C/minute, then water quenching. The austenite saw by using optic microscope and count by ASTM E112 method. From the results it is concluded that there is a relationship between temperatures interrelated heating, heating rate and holding time on the growth of austenite grain. The higher the temperature, the heating occur austenite grain size. While the most optimal results obtained for reheated temperature 1060°C with a heating rate 7.5°C/minute and the heating temperature 1120°C with a heating rate 5°C/minute.

  9. Aerodynamics at NASA JSC

    NASA Technical Reports Server (NTRS)

    Vicker, Darby

    2006-01-01

    A viewgraph presentation describing aerodynamics at NASA Johnson Space Center is shown. The topics include: 1) Personal Background; 2) Aerodynamic Tools; 3) The Overset Computational Fluid Dynamics (CFD) Process; and 4) Recent Applicatoins.

  10. Classical Aerodynamic Theory

    NASA Technical Reports Server (NTRS)

    Jones, R. T. (Compiler)

    1979-01-01

    A collection of papers on modern theoretical aerodynamics is presented. Included are theories of incompressible potential flow and research on the aerodynamic forces on wing and wing sections of aircraft and on airship hulls.

  11. Mixing rates and vertical heat fluxes north of Svalbard from Arctic winter to spring

    NASA Astrophysics Data System (ADS)

    Meyer, Amelie; Fer, Ilker; Sundfjord, Arild; Peterson, Algot K.

    2017-06-01

    Mixing and heat flux rates collected in the Eurasian Basin north of Svalbard during the N-ICE2015 drift expedition are presented. The observations cover the deep Nansen Basin, the Svalbard continental slope, and the shallow Yermak Plateau from winter to summer. Mean quiescent winter heat flux values in the Nansen Basin are 2 W m-2 at the ice-ocean interface, 3 W m-2 in the pycnocline, and 1 W m-2 below the pycnocline. Large heat fluxes exceeding 300 W m-2 are observed in the late spring close to the surface over the Yermak Plateau. The data consisting of 588 microstructure profiles and 50 days of high-resolution under-ice turbulence measurements are used to quantify the impact of several forcing factors on turbulent dissipation and heat flux rates. Wind forcing increases turbulent dissipation seven times in the upper 50 m, and doubles heat fluxes at the ice-ocean interface. The presence of warm Atlantic Water close to the surface increases the temperature gradient in the water column, leading to enhanced heat flux rates within the pycnocline. Steep topography consistently enhances dissipation rates by a factor of four and episodically increases heat flux at depth. It is, however, the combination of storms and shallow Atlantic Water that leads to the highest heat flux rates observed: ice-ocean interface heat fluxes average 100 W m-2 during peak events and are associated with rapid basal sea ice melt, reaching 25 cm/d.

  12. NASA aerodynamics program

    NASA Technical Reports Server (NTRS)

    Williams, Louis J.; Hessenius, Kristin A.; Corsiglia, Victor R.; Hicks, Gary; Richardson, Pamela F.; Unger, George; Neumann, Benjamin; Moss, Jim

    1992-01-01

    The annual accomplishments is reviewed for the Aerodynamics Division during FY 1991. The program includes both fundamental and applied research directed at the full spectrum of aerospace vehicles, from rotorcraft to planetary entry probes. A comprehensive review is presented of the following aerodynamics elements: computational methods and applications; CFD validation; transition and turbulence physics; numerical aerodynamic simulation; test techniques and instrumentation; configuration aerodynamics; aeroacoustics; aerothermodynamics; hypersonics; subsonics; fighter/attack aircraft and rotorcraft.

  13. NASA aerodynamics program

    NASA Technical Reports Server (NTRS)

    Holmes, Bruce J.; Schairer, Edward; Hicks, Gary; Wander, Stephen; Blankson, Isiaiah; Rose, Raymond; Olson, Lawrence; Unger, George

    1990-01-01

    Presented here is a comprehensive review of the following aerodynamics elements: computational methods and applications, computational fluid dynamics (CFD) validation, transition and turbulence physics, numerical aerodynamic simulation, drag reduction, test techniques and instrumentation, configuration aerodynamics, aeroacoustics, aerothermodynamics, hypersonics, subsonic transport/commuter aviation, fighter/attack aircraft and rotorcraft.

  14. Analysis on the Factors of Heat Transfer Rate and Air Volume in Tunnel

    NASA Astrophysics Data System (ADS)

    Du, Cuifeng; Bian, Menglong

    2017-05-01

    In order to obtain the relationship between ventilation and heat transfer of tunnel under certain conditions, the paper analyses the convective heat transfer phenomenon under the limited conditions of driving tunnel. A simplified mathematical formula is established between heat transfer rate and air volume, which explained a phenomenon that the cooling effect is hard to be improved as air volume is increasing and in actual ventilation. According to the established mathematical formula, the ratio of heat transfer rate to air volume is analyzed in different circumstances through the field experiment and numerical simulation. A conclusion is drawn that the ratio of Φ/Q can be proposed to evaluate the ventilation cooling effect.

  15. Computer simulation of metal wire explosion under high rate heating

    NASA Astrophysics Data System (ADS)

    Zolnikov, K. P.; Kryzhevich, D. S.; Korchuganov, A. V.

    2017-05-01

    Synchronous electric explosion of metal wires and synthesis of bicomponent nanoparticles were investigated on the base of molecular dynamics method. Copper and nickel nanosized crystallites of cylindrical shape were chosen as conductors for explosion. The embedded atom approximation was used for calculation of the interatomic interactions. The agglomeration process after explosion metal wires was the main mechanism for particle synthesis. The distribution of chemical elements was non-uniform over the cross section of the bicomponent particles. The copper concentration in the surface region was higher than in the bulk of the synthesized particle. By varying the loading parameters (heating temperature, the distance between the wires) one can control the size and internal structure of the synthesized bicomponent nanoparticles. The obtained results showed that the method of molecular dynamics can be effectively used to determine the optimal technological mode of nanoparticle synthesis on the base of electric explosion of metal wires.

  16. The effect of heating rate on the surface chemistry of NiTi.

    PubMed

    Undisz, Andreas; Hanke, Robert; Freiberg, Katharina E; Hoffmann, Volker; Rettenmayr, Markus

    2014-11-01

    The impact of the heating rate on the Ni content at the surface of the oxide layer of biomedical NiTi is explored. Heat treatment emulating common shape-setting procedures was performed by means of conventional and inductive heating for similar annealing time and temperature, applying various heating rates from ~0.25 K s(-1) to 250 K s(-1). A glow discharge optical emission spectroscopy method was established and employed to evaluate concentration profiles of Ni, Ti and O in the near-surface region at high resolution. The Ni content at the surface of the differently treated samples varies significantly, with maximum surface Ni concentrations of ~20 at.% at the lowest and ~1.5 at.% at the highest heating rate, i.e. the total amount of Ni contained in the surface region of the oxide layer decreases by >15 times. Consequently, the heating rate is a determinant for the biomedical characteristics of NiTi, especially since Ni available at the surface of the oxide layer may affect the hemocompatibility and be released promptly after surgical application of a respective implant. Furthermore, apparently contradictory results presented in the literature reporting surface Ni concentrations of ~3 at.% to >20 at.% after heat treatment are consistently explained considering the ascertained effect of the heating rate.

  17. Leakage rates and thermal requirements for the diffusion bonding of microchannel arrays via internal convective heating

    SciTech Connect

    Bose, Sumantra; Palo, Daniel R.; Paul, Brian

    2007-07-24

    Diffusion bonding cycle times can be a large cost factor in the production of metal microchannel devices. The challenge is to significantly minimize this cost by reducing the bonding cycle time through rapid and uniform heating and cooling within the bonding process. Heating rates in diffusion bonding processes are typically limited by the need to minimize thermal gradients during bonding. A novel method is described which takes advantage of the internal flow passages within microchannel devices for convective heat transfer during the bonding process. The internal convective heating (ICH) technique makes use of heated inert gas to provide the microchannel assembly with rapid and uniform heat input. This paper will demonstrate the ability to effectively diffusion bond microchannel laminae using the ICH method by investigating the leakage rates.

  18. Effect of the Heat Flux Density on the Evaporation Rate of a Distilled Water Drop

    NASA Astrophysics Data System (ADS)

    Ponomarev, Konstantin; Orlova, Evgeniya; Feoktistov, Dmitry

    2016-02-01

    This paper presents the experimental dependence of the evaporation rate of a nondeaerated distilled water drop from the heat flux density on the surfaces of non-ferrous metals (copper and brass). A drop was placed on a heated substrate by electronic dosing device. To obtain drop profile we use a shadow optical system; drop symmetry was controlled by a high-speed video camera. It was found that the evaporation rate of a drop on a copper substrate is greater than on a brass. The evaporation rate increases intensively with raising volume of a drop. Calculated values of the heat flux density and the corresponding evaporation rates are presented in this work. The evaporation rate is found to increase intensively on the brass substrate with raising the heat flux density.

  19. Effects of mass flow rate and droplet velocity on surface heat flux during cryogen spray cooling.

    PubMed

    Karapetian, Emil; Aguilar, Guillermo; Kimel, Sol; Lavernia, Enrique J; Nelson, J Stuart

    2003-01-07

    Cryogen spray cooling (CSC) is used to protect the epidermis during dermatologic laser surgery. To date, the relative influence of the fundamental spray parameters on surface cooling remains incompletely understood. This study explores the effects of mass flow rate and average droplet velocity on the surface heat flux during CSC. It is shown that the effect of mass flow rate on the surface heat flux is much more important compared to that of droplet velocity. However, for fully atomized sprays with small flow rates, droplet velocity can make a substantial difference in the surface heat flux.

  20. Effect of heat rate constraint on minimum-fuel synergetic plane change

    NASA Technical Reports Server (NTRS)

    Mease, Kenneth D.; Utashima, Masayoshi

    1991-01-01

    The synergetic plane change offers substantial fuel savings over the pure-propulsive alternative for certain noncoplanar orbital transfers. On the other hand, the thermal environment for a synergetic plane change vehicle can be quite severe. The minimum-fuel controls are computed approximately by parametrizing the controls and solving the resulting nonlinear programming problem. By considering several different levels of heat rate constraint, we characterize how the control strategy should be modified in order to keep the heat rate below the specified limit. Flight on the heat rate constraint boundary at high angle of attack is the key characteristic.

  1. Space Shuttle Orbiter flight heating rate measurement sensitivity to thermal protection system uncertainties

    NASA Technical Reports Server (NTRS)

    Bradley, P. F.; Throckmorton, D. A.

    1981-01-01

    A study was completed to determine the sensitivity of computed convective heating rates to uncertainties in the thermal protection system thermal model. Those parameters considered were: density, thermal conductivity, and specific heat of both the reusable surface insulation and its coating; coating thickness and emittance; and temperature measurement uncertainty. The assessment used a modified version of the computer program to calculate heating rates from temperature time histories. The original version of the program solves the direct one dimensional heating problem and this modified version of The program is set up to solve the inverse problem. The modified program was used in thermocouple data reduction for shuttle flight data. Both nominal thermal models and altered thermal models were used to determine the necessity for accurate knowledge of thermal protection system's material thermal properties. For many thermal properties, the sensitivity (inaccuracies created in the calculation of convective heating rate by an altered property) was very low.

  2. Can Reptile Embryos Influence Their Own Rates of Heating and Cooling?

    PubMed Central

    Du, Wei-Guo; Tu, Ming-Chung; Shine, Richard

    2013-01-01

    Previous investigations have assumed that embryos lack the capacity of physiological thermoregulation until they are large enough for their own metabolic heat production to influence nest temperatures. Contrary to intuition, reptile embryos may be capable of physiological thermoregulation. In our experiments, egg-sized objects (dead or infertile eggs, water-filled balloons, glass jars) cooled down more rapidly than they heated up, whereas live snake eggs heated more rapidly than they cooled. In a nest with diel thermal fluctuations, that hysteresis could increase the embryo’s effective incubation temperature. The mechanisms for controlling rates of thermal exchange are unclear, but may involve facultative adjustment of blood flow. Heart rates of snake embryos were higher during cooling than during heating, the opposite pattern to that seen in adult reptiles. Our data challenge the view of reptile eggs as thermally passive, and suggest that embryos of reptile species with large eggs can influence their own rates of heating and cooling. PMID:23826200

  3. The effect of ohmic heating on vacuum drying rate of sweet potato tissue.

    PubMed

    Zhong, Tuoxiu; Lima, Marybeth

    2003-05-01

    Ohmically heating fruit and vegetable tissue has been shown to increase hot-air drying rate, shift desorption isotherms, and increase juice extraction yields with respect to untreated, conventionally heated, and microwaved samples. The objective of this study was to determine if ohmically heating sweet potato tissue would enhance the vacuum drying rate of these samples with respect to untreated samples. Sweet potato cubes were ohmically heated to three endpoint temperatures using three electrical field strengths and were then placed in a freeze dryer. Moisture content vs. time data were collected and modeled. Results showed that the vacuum drying rates of ohmically heated samples were faster than raw samples for most treatment combinations, and that the maximum reduction of drying time was 24%. Minimal ohmic treatment can result in a significant decrease in vacuum drying time, which could have important economic and product quality implications.

  4. Tailoring the characteristics of carbonized wood charcoal by using different heating rates

    NASA Astrophysics Data System (ADS)

    Kwon, Gu-Joong; Kim, Dae-Young; Oh, Choong-Hyeon; Park, Byung-Ho; Kang, Joo-Hyon

    2014-05-01

    This study examined the characteristics of charcoals generated from White Lauan ( Pentacmecontorta) and Punah ( Tetrameristaglabra) by using different carbonization temperatures and heating rates. The scanning electron micrographs showed vestured pits in the White Lauan and raphide crystals in Punah as their respective anatomical characteristics. A slower heating rate resulted in a lower temperature to obtain the same amount of weight loss, regardless of the species being tested. A greater charcoal yield was obtained at a higher heating rate. The specific surface area was smaller in the charcoal produced at a higher carbonization temperature, but the heating rate had little effected. For both wood species, the axial compressive strength of the charcoal increased as the carbonization temperature was increased. The X-ray diffractograms of White Lauan and Punah woods heated at 1200°C indicated thermal decomposition of the crystal structure of cellulose, but no appreciable structural changes occurred under the tested heating rate conditions. Overall, the heating rate affected the charcoal yield but not the specific surface area, compressive strength, and crystal structure.

  5. The effect of heat transfer mode on heart rate responses and hysteresis during heating and cooling in the estuarine crocodile Crocodylus porosus.

    PubMed

    Franklin, Craig E; Seebacher, Frank

    2003-04-01

    The effect of heating and cooling on heart rate in the estuarine crocodile Crocodylus porosus was studied in response to different heat transfer mechanisms and heat loads. Three heating treatments were investigated. C. porosus were: (1) exposed to a radiant heat source under dry conditions; (2) heated via radiant energy while half-submerged in flowing water at 23 degrees C and (3) heated via convective transfer by increasing water temperature from 23 degrees C to 35 degrees C. Cooling was achieved in all treatments by removing the heat source and with C. porosus half-submerged in flowing water at 23 degrees C. In all treatments, the heart rate of C. porosus increased markedly in response to heating and decreased rapidly with the removal of the heat source. Heart rate during heating was significantly faster than during cooling at any given body temperature, i.e. there was a significant heart rate hysteresis. There were two identifiable responses to heating and cooling. During the initial stages of applying or removing the heat source, there was a dramatic increase or decrease in heart rate ('rapid response'), respectively, indicating a possible cardiac reflex. This rapid change in heart rate with only a small change or no change in body temperature (<0.5 degrees C) resulted in Q(10) values greater than 4000, calling into question the usefulness of this measure on heart rate during the initial stages of heating and cooling. In the later phases of heating and cooling, heart rate changed with body temperature, with Q(10) values of 2-3. The magnitude of the heart rate response differed between treatments, with radiant heating during submergence eliciting the smallest response. The heart rate of C. porosus outside of the 'rapid response' periods was found to be a function of the heat load experienced at the animal surface, as well as on the mode of heat transfer. Heart rate increased or decreased rapidly when C. porosus experienced large positive (above 25 W) or negative

  6. Approximate Method of Calculating Heating Rates at General Three-Dimensional Stagnation Points During Atmospheric Entry

    NASA Technical Reports Server (NTRS)

    Hamilton, H. H., II

    1982-01-01

    An approximate method for calculating heating rates at general three dimensional stagnation points is presented. The application of the method for making stagnation point heating calculations during atmospheric entry is described. Comparisons with results from boundary layer calculations indicate that the method should provide an accurate method for engineering type design and analysis applications.

  7. Flash-Fire Propensity and Heat-Release Rate Studies of Improved Fire Resistant Materials

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.

    1978-01-01

    Twenty-six improved fire resistant materials were tested for flash-fire propensity and heat release rate properties. The tests were conducted to obtain a descriptive index based on the production of ignitable gases during the thermal degradation process and on the response of the materials under a specific heat load.

  8. Aerodynamics of sports balls

    NASA Technical Reports Server (NTRS)

    Mehta, R. D.

    1985-01-01

    Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.

  9. Aerodynamics of sports balls

    NASA Technical Reports Server (NTRS)

    Mehta, R. D.

    1985-01-01

    Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.

  10. Aerodynamics of sports balls

    NASA Astrophysics Data System (ADS)

    Mehta, R. D.

    Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.

  11. The rate and risk of heat-related illness in hospital emergency departments during the 1995 Chicago heat disaster.

    PubMed

    Rydman, R J; Rumoro, D P; Silva, J C; Hogan, T M; Kampe, L M

    1999-02-01

    To conduct an Emergency Department (ED)-based treated prevalence study of heat morbidity and to estimate the rate and risk of heat morbid events for all Chicago MSA EDs (N = 95; 2.7 million visits per year). ED patient log data were compiled from 13 randomly selected hospitals located throughout the Chicago MSA during the 2 weeks of the 1995 heat disaster and from the same 2-week period in 1994 (controls). Measurements included: age, sex, date, and time of ED service, up to three ICD-9 diagnoses, and disposition. Heat morbidity for Chicago MSA hospital EDs was calculated at 4,224 (95% CI = 2964-5488) cases. ED heat morbidity increased significantly 5 days prior to the first heat-related death. In 1995, there was an increase in the estimated relative risk for the city = 3.85 and suburbs = 1.89 over the control year of 1994. Real time ED-based computer automated databanks should be constructed to improve public health response to infectious or noninfectious outbreaks. Rapid area-wide M&M tabulations can be used for advancing the effectiveness of community-based prevention programs, and anticipating hospital ED resource allocation.

  12. A "TEST OF CONCEPT" COMPARISON OF AERODYNAMIC AND MECHANICAL RESUSPENSION MECHANISMS FOR PARTICLES DEPOSITED ON FIELD RYE GRASS (SECALE CERCELE). PART I. RELATIVE PARTICLE FLUX RATES

    EPA Science Inventory

    Resuspension of uniform latex micro spheres deposited on a single seed pod of field rye grass stalk and head was investigated experimentally in a wind tunnel. The experiment was designed to distinguish aerodynamic (viscous and turbulent) mechanisms from mechanical resuspension re...

  13. A "TEST OF CONCEPT" COMPARISON OF AERODYNAMIC AND MECHANICAL RESUSPENSION MECHANISMS FOR PARTICLES DEPOSITED ON FIELD RYE GRASS (SECALE CERCELE). PART I. RELATIVE PARTICLE FLUX RATES

    EPA Science Inventory

    Resuspension of uniform latex micro spheres deposited on a single seed pod of field rye grass stalk and head was investigated experimentally in a wind tunnel. The experiment was designed to distinguish aerodynamic (viscous and turbulent) mechanisms from mechanical resuspension re...

  14. Local Aerodynamic Heat Transfer and Boundary-Layer Transition on Roughened Sphere-Ellipsoid Bodies at Mach Number 3.0

    NASA Technical Reports Server (NTRS)

    Deveikis, William D.; Walker, Robert W.

    1961-01-01

    A wind-tunnel investigation was made to determine heat-transfer distributions on three steel sphere-ellipsoid bodies with surface roughnesses of 5, 100, and 200 microinches. Tests were conducted in the Langley 9- by 6-foot thermal structures tunnel at a Mach number of 3.0, free-stream Reynolds numbers (based on model spherical diameter) of 4.25 x 10(exp 6) and 2.76 x l0(exp 6), and at a stagnation temperature of 650 F. Pressure distributions were obtained also on a fourth model. The results indicated that the combination of surface roughness and boundary-layer cooling tended to promote early transition and nullify the advantages attributable to the blunt shape of the model for reducing local temperatures. Good correlation between experimental heating rates and those calculated from laminar theory was achieved up to the start of boundary-layer transition. The correlation also was good with the values predicted by turbulent theory for surface stations downstream from the 45 deg. station.

  15. Heat-Rate Improvement Obtained by Retubing Power-Plant Condenser Enhanced Tubes

    SciTech Connect

    1994-01-21

    A utility will only retube a condenser with enhanced tubes if the incremental cost of the enhanced tubes can be offset with reduced fuel costs. The reduced fuel cost is obtained for some units because of the higher heat-transfer coefficient of enhanced tubes. They lead to improved condenser performance measured by a lower condenser pressure and therefore a more efficient power plant. However, the higher haet-transfer coefficients do not always guarantee that enhanced tubes will be more cost effective. Other issues must be considered such as the cooling-water flow reduction due to the increased pressure drop, the low-pressure turbine heat-rate variation with backpressure, and the cooling-water pump and system characteristics. These and other parameters must be considered to calculate the efficiency improvement of the power plant as commonly measured by the quantity known as the heat rate. Knowing the heat-rate improvement, the fuel cost, and the incremental increase of the enhanced tubes from the supplier, the payback time can be determined. This program calculates the heat-rate improvement that can be obtained by retubing a power plant condenser with enhanced tubes of a particular type called Korodense LPD made by Wolverine Tube, Inc. The fuel savings are easily established knowing the heat-rate improvement. All electrical utilities are potential users because a condenser is used as the heat sink for every power plant.

  16. HTRATE; Heat-Rate Improvement Obtained by Retubing Power-Plant Condenser Enhanced Tubes

    SciTech Connect

    Rabas, T.J.

    1990-06-01

    A utility will only retube a condenser with enhanced tubes if the incremental cost of the enhanced tubes can be offset with reduced fuel costs. The reduced fuel cost is obtained for some units because of the higher heat-transfer coefficient of enhanced tubes. They lead to improved condenser performance measured by a lower condenser pressure and therefore a more efficient power plant. However, the higher haet-transfer coefficients do not always guarantee that enhanced tubes will be more cost effective. Other issues must be considered such as the cooling-water flow reduction due to the increased pressure drop, the low-pressure turbine heat-rate variation with backpressure, and the cooling-water pump and system characteristics. These and other parameters must be considered to calculate the efficiency improvement of the power plant as commonly measured by the quantity known as the heat rate. Knowing the heat-rate improvement, the fuel cost, and the incremental increase of the enhanced tubes from the supplier, the payback time can be determined. This program calculates the heat-rate improvement that can be obtained by retubing a power plant condenser with enhanced tubes of a particular type called Korodense LPD made by Wolverine Tube, Inc. The fuel savings are easily established knowing the heat-rate improvement. All electrical utilities are potential users because a condenser is used as the heat sink for every power plant.

  17. Heating rate effects during non-isothermal annealing of AIK steel

    NASA Astrophysics Data System (ADS)

    Sahay, Satyam S.; Joshi, Kishor B.

    2003-04-01

    The effects of heating rate on microstructural size and shape parameters during annealing of cold rolled aluminum killed steel strips have been examined under non-isothermal condition. It is shown that decrease in the heating rate results in accelerated grain growth behavior compared with the prediction by quasi-isothermal based kinetics. The {111} and {112} crystallographic orientations, which enhance the normal anisotropy and deep drawability of cold rolled annealed sheets, are found to exhibit a strong correlation with the grain shape anisotropy. This grain shape anisotropy itself is strongly dependent on heating rates. Lower heating rates result in higher aspect ratios and thus better drawability of the cold rolled sheets. A Hall-Petch type relationship is observed between grain size and hardness of the annealed samples.

  18. Heat transfer in a microvascular network: the effect of heart rate on heating and cooling in reptiles (Pogona barbata and Varanus varius).

    PubMed

    Seebacher, F

    2000-03-21

    Thermally-induced changes in heart rate and blood flow in reptiles are believed to be of selective advantage by allowing animal to exert some control over rates of heating and cooling. This notion has become one of the principal paradigms in reptilian thermal physiology. However, the functional significance of changes in heart rate is unclear, because the effect of heart rate and blood flow on total animal heat transfer is not known. I used heat transfer theory to determine the importance of heat transfer by blood flow relative to conduction. I validated theoretical predictions by comparing them with field data from two species of lizard, bearded dragons (Pogona barbata) and lace monitors (Varanus varius). Heart rates measured in free-ranging lizards in the field were significantly higher during heating than during cooling, and heart rates decreased with body mass. Convective heat transfer by blood flow increased with heart rate. Rates of heat transfer by both blood flow and conduction decreased with mass, but the mass scaling exponents were different. Hence, rate of conductive heat transfer decreased more rapidly with increasing mass than did heat transfer by blood flow, so that the relative importance of blood flow in total animal heat transfer increased with mass. The functional significance of changes in heart rate and, hence, rates of heat transfer, in response to heating and cooling in lizards was quantified. For example, by increasing heart rate when entering a heating environment in the morning, and decreasing heart rate when the environment cools in the evening a Pogona can spend up to 44 min longer per day with body temperature within its preferred range. It was concluded that changes in heart rate in response to heating and cooling confer a selective advantage at least on reptiles of mass similar to that of the study animals (0. 21-5.6 kg).

  19. An analysis of representative heating load lines for residential HSPF ratings

    SciTech Connect

    Rice, C. Keith; Shen, Bo; Shrestha, Som S.

    2015-07-01

    This report describes an analysis to investigate representative heating loads for single-family detached homes using current EnergyPlus simulations (DOE 2014a). Hourly delivered load results are used to determine binned load lines using US Department of Energy (DOE) residential prototype building models (DOE 2014b) developed by Pacific Northwest National Laboratory (PNNL). The selected residential single-family prototype buildings are based on the 2006 International Energy Conservation Code (IECC 2006) in the DOE climate regions. The resulting load lines are compared with the American National Standards Institute (ANSI)/Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Standard 210/240 (AHRI 2008) minimum and maximum design heating requirement (DHR) load lines of the heating seasonal performance factor (HSPF) ratings procedure for each region. The results indicate that a heating load line closer to the maximum DHR load line, and with a lower zero load ambient temperature, is more representative of heating loads predicted for EnergyPlus prototype residential buildings than the minimum DHR load line presently used to determine HSPF ratings. An alternative heating load line equation was developed and compared to binned load lines obtained from the EnergyPlus simulation results. The effect on HSPF of the alternative heating load line was evaluated for single-speed and two-capacity heat pumps, and an average HSPF reduction of 16% was found. The alternative heating load line relationship is tied to the rated cooling capacity of the heat pump based on EnergyPlus autosizing, which is more representative of the house load characteristics than the rated heating capacity. The alternative heating load line equation was found to be independent of climate for the six DOE climate regions investigated, provided an adjustable zero load ambient temperature is used. For Region IV, the default DOE climate region used for HSPF ratings, the higher load line results in an ~28

  20. Enhancement of heat transfer rate on phase change materials with thermocapillary flows

    NASA Astrophysics Data System (ADS)

    Madruga, Santiago; Mendoza, Carolina

    2016-07-01

    We carry out simulations of the melting process on the phase change material n-octadecane in squared geometries in the presence of natural convection and including thermocapillary effects. We show how the introduction of thermocapillary effects enhances the heat transfer rate, being the effect especially relevant for small Bond numbers. Thus induction of Marangoni flows results in a useful mechanism to enhance the typical slow heat transfer rate of paraffin waxes in applications of energy storage or passive control management.

  1. Enhancement of heat transfer rate on phase change materials with thermocapillary flows

    NASA Astrophysics Data System (ADS)

    Madruga, Santiago; Mendoza, Carolina

    2017-04-01

    We carry out simulations of the melting process on the phase change material n-octadecane in squared geometries in the presence of natural convection and including thermocapillary effects. We show how the introduction of thermocapillary effects enhances the heat transfer rate, being the effect especially relevant for small Bond numbers. Thus induction of Marangoni flows results in a useful mechanism to enhance the typical slow heat transfer rate of paraffin waxes in applications of energy storage or passive control management.

  2. Effect of a finite ionization rate on the radiative heating of outer planet atmospheric entry probes

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1982-01-01

    The influence of finite rate ionization in the inviscid gas just behind the stagnation shock wave on the radiative heating of probes entering the hydrogen-helium atmosphere of the major plants was investigated. Two opposing conclusions were reached as to how the ionization rate assumption affects the radiative transfer. Hydrogen-helium shock waves with a cold nonblowing wall boundary condition at the probe heat shield are emphasized. The study is limited to the stagnation shock layer.

  3. Solid motor aft closure insulation erosion. [heat flux correlation for rate analysis

    NASA Technical Reports Server (NTRS)

    Stampfl, E.; Landsbaum, E. M.

    1973-01-01

    The erosion rate of aft closure insulation in a number of large solid propellant motors was empirically analyzed by correlating the average ablation rate with a number of variables that had previously been demonstrated to affect heat flux. The main correlating parameter was a heat flux based on the simplified Bartz heat transfer coefficient corrected for two-dimensional effects. A multiplying group contained terms related to port-to-throat ratio, local wall angle, grain geometry and nozzle cant angle. The resulting equation gave a good correlation and is a useful design tool.

  4. Experimental test of the heating and cooling rate effect on blocking temperatures

    NASA Astrophysics Data System (ADS)

    Berndt, Thomas; Paterson, Greig A.; Cao, Changqian; Muxworthy, Adrian R.

    2017-07-01

    The cooling rates at which rocks acquire thermoremanent magnetizations (TRMs), affect their unblocking temperatures in thermal demagnetization experiments; similarly the heating rates at which the thermal demagnetization experiments are done also affect the unblocking temperature. We have tested the effects of variable cooling and heating rates on the unblocking temperatures of two natural non-interacting, magnetically uniform (single-domain, SD) (titano)magnetite samples and a synthetic SD magnetoferritin sample. While previous studies have only considered unblocking temperatures for stepwise thermal demagnetization data (i.e. the room-temperature magnetization after incremental heating), in this work we derive an expression for continuous thermal demagnetization of both TRMs and viscous remanent magnetizations (VRMs) and relate the heating rate to an effective equivalent hold time of a stepwise thermal demagnetization experiment. Through our analysis we reach four main conclusions: First, the theoretical expressions for the heating/cooling rate effect do not accurately predict experimentally observed blocking temperatures. Empirically, the relation can be modified incorporating a factor that amplifies both the temperature and the heating rate dependence of the heating/cooling rate effect. Using these correction factors, Pullaiah nomograms can accurately predict blocking temperatures of both TRMs and VRMs for continuous heating/cooling. Second, demagnetization temperatures are approximately predicted by published 'Pullaiah nomograms', but blocking occurs gradually over temperature intervals of 5-40 K. Third, the theoretically predicted temperatures correspond to ∼54-82 per cent blocking, depending on the sample. Fourth, the blocking temperatures can be used to obtain estimates of the atomic attempt time τ0, which were found to be 3 × 10-10 s for large grained (titano)magnetite, 1 × 10-13 s for small grained (titano)magnetite below the Verwey transition and 9

  5. Hysteresis of heart rate and heat exchange of fasting and postprandial savannah monitor lizards (Varanus exanthematicus).

    PubMed

    Zaar, Morten; Larsen, Einer; Wang, Tobias

    2004-04-01

    Reptiles are ectothermic, but regulate body temperatures (T(b)) by behavioural and physiological means. Body temperature has profound effects on virtually all physiological functions. It is well known that heating occurs faster than cooling, which seems to correlate with changes in cutaneous perfusion. Increased cutaneous perfusion, and hence elevated cardiac output, during heating is reflected in an increased heart rate (f(H)), and f(H), at a given T(b), is normally higher during heating compared to cooling ('hysteresis of heart rate'). Digestion is associated with an increased metabolic rate. This is associated with an elevated f(H) and many species of reptiles also exhibited a behavioural selection of higher T(b) during digestion. Here, we examine whether digestion affects the rate of heating and cooling as well as the hysteresis of heart rate in savannah monitor lizards (Varanus exanthematicus). Fasting lizards were studied after 5 days of food deprivation while digesting lizards were studied approximately 24 h after ingesting dead mice that equalled 10% of their body mass. Heart rate was measured while T(b) increased from 28 to 38 degrees C under a heat lamp and while T(b) decreased during a subsequent cooling phase. The lizards exhibited hysteresis of heart rate, and heating occurred faster than cooling. Feeding led to an increased f(H) (approximately 20 min(-1) irrespective of T(b)), but did not affect the rate of temperature change during heating or cooling. Therefore, it is likely that the increased blood flows during digestion are distributed exclusively to visceral organs and that the thermal conductance remains unaffected by the elevated metabolic rate during digestion.

  6. Radiative heating rates during AAOE and AASE. [Airborne Antarctic Ozone Experiment and Airborne Arctic Stratospheric Experiment

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.

    1990-01-01

    Radiative transit computations of heating rates utilizing data from the 1987 Airborne Antarctic Ozone Experiment (AAOE) (Tuck et al., 1989) and the 1989 Airborne Arctic Stratospheric Experiment (AASE) (Turco et al., 1990) are described. Observed temperature and ozone profiles and a radiative transfer model are used to compute the heating rates for the Southern Hemisphere during AAOE and the Northern Hemisphere during AASE. The AASE average cooling rates computed inside the vortex are in good agreement with the diabatic cooling rates estimated from the ER-2 profile data for N2O for the AASE period (Schoeberl et al., 1989).

  7. Thermal Death Kinetics of Conogethes Punctiferalis (Lepidoptera: Pyralidae) as Influenced by Heating Rate and Life Stage.

    PubMed

    Hou, Lixia; Du, Yanli; Johnson, Judy A; Wang, Shaojin

    2015-10-01

    Thermal death kinetics of Conogethes punctiferalis (Guenée) (Lepidoptera: Pyralidae) at different life stages, heating rate, and temperature is essential for developing postharvest treatments to control pests in chestnuts. Using a heating block system (HBS), the most heat-tolerant life stage of C. punctiferalis and the effects of heating rate (0.1, 0.5, 1, 5, and 10°C/min) on insect mortality were determined. The thermal death kinetic data of fifth-instar C. punctiferalis were obtained at temperatures between 44 and 50°C at a heating rate of 5°C/min. The results showed that the relative heat tolerance of C. punctiferalis was found to be fifth instars>pupae> third instars> eggs. To avoid the enhanced thermal tolerance of C. punctiferalis at low heating rates (0.1 or 0.5°C/min), a high heating rate of 5°C/min was selected to simulate the fast radio frequency heating in chestnuts and further determine the thermal death kinetic data. Thermal death curves of C. punctiferalis followed a 0th-order kinetic reaction model. The minimum exposure time to achieve 100% mortality was 55, 12, 6, and 3 min at 44, 46, 48, and 50°C, respectively. The activation energy for controlling C. punctiferalis was 482.15 kJ/mol with the z value of 4.09°C obtained from the thermal death-time curve. The information provided by thermal death kinetics for C. punctiferalis is useful in developing effective postharvest thermal treatment protocols for disinfesting chestnuts.

  8. Effect of Heating Rate on the Pressureless Sintering Densification of a Nickel-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Levasseur, David; Brochu, Mathieu

    2016-05-01

    Pressureless sintering of Inconel 718 has important technological applications for the densification of metal injection molding or additive manufacturing of parts with powder/binder systems. The effect of heating rates ranging from 15 to 200 K/minute on the sintering behavior of fine (-325 mesh) Inconel 718 powders was studied using the master sintering curve (MSC) concept. A pressureless pulsed electric current sintering setup was used to heat samples. The temperature at the onset of sintering increased as the heating rate increased. The formation of a supersolidus liquid fraction was shifted toward higher temperatures for increased heating rates. The apparent activation energy of sintering was obtained by least squares fitting of the sintering data to the MSC and was in good agreement with the lattice diffusion activation energy of the alloying elements present in Inconel 718. The MSC followed different kinetics for low heating rates (≤50 K/minute) and high heating rates (≥75 K/minute), and these differences were related to liquation kinetics.

  9. Dependence of Dynamic Tensile Strength of Longyou Sandstone on Heat-Treatment Temperature and Loading Rate

    NASA Astrophysics Data System (ADS)

    Yao, Wei; Xu, Ying; Wang, Wei; Kanopolous, Patrick

    2016-10-01

    As a material for famous historical underground rock caverns, Longyou sandstone (LS) may fail under the combination of high loading rate and high temperature. The thermal damage induced by various heat-treatment temperatures (150, 250, 350, 450, 600 and 850 °C) is first characterized by X-ray Micro-computed tomography (CT) method. The damage variable derived from the average CT value for heat-treated LS specimen and reference specimen without heat treatment was used to quantify the thermal damage. The dynamic tensile strengths of these LS samples under different dynamic loading rates (ranging from 24 to 540 GPa/s) were then obtained using the split Hopkinson pressure bar (SHPB) system. The dynamic tensile strength of LS increases with the loading rate at a given heat-treatment temperature, and the tensile strength at the same loading rate decreases with the heat-treatment temperature except for 450 °C. Based on the experimental data, an empirical equation was established to relate the dynamic tensile strength of LS to the loading rate and the heat-treatment temperature.

  10. Influence of heat transfer rates on pressurization of liquid/slush hydrogen propellant tanks

    NASA Technical Reports Server (NTRS)

    Sasmal, G. P.; Hochstein, J. I.; Hardy, T. L.

    1993-01-01

    A multi-dimensional computational model of the pressurization process in liquid/slush hydrogen tank is developed and used to study the influence of heat flux rates at the ullage boundaries on the process. The new model computes these rates and performs an energy balance for the tank wall whereas previous multi-dimensional models required a priori specification of the boundary heat flux rates. Analyses of both liquid hydrogen and slush hydrogen pressurization were performed to expose differences between the two processes. Graphical displays are presented to establish the dependence of pressurization time, pressurant mass required, and other parameters of interest on ullage boundary heat flux rates and pressurant mass flow rate. Detailed velocity fields and temperature distributions are presented for selected cases to further illuminate the details of the pressurization process. It is demonstrated that ullage boundary heat flux rates do significantly effect the pressurization process and that minimizing heat loss from the ullage and maximizing pressurant flow rate minimizes the mass of pressurant gas required to pressurize the tank. It is further demonstrated that proper dimensionless scaling of pressure and time permit all the pressure histories examined during this study to be displayed as a single curve.

  11. Influence of heat transfer rates on pressurization of liquid/slush hydrogen propellant tanks

    NASA Technical Reports Server (NTRS)

    Sasmal, G. P.; Hochstein, J. I.; Hardy, T. L.

    1993-01-01

    A multi-dimensional computational model of the pressurization process in liquid/slush hydrogen tank is developed and used to study the influence of heat flux rates at the ullage boundaries on the process. The new model computes these rates and performs an energy balance for the tank wall whereas previous multi-dimensional models required a priori specification of the boundary heat flux rates. Analyses of both liquid hydrogen and slush hydrogen pressurization were performed to expose differences between the two processes. Graphical displays are presented to establish the dependence of pressurization time, pressurant mass required, and other parameters of interest on ullage boundary heat flux rates and pressurant mass flow rate. Detailed velocity fields and temperature distributions are presented for selected cases to further illuminate the details of the pressurization process. It is demonstrated that ullage boundary heat flux rates do significantly effect the pressurization process and that minimizing heat loss from the ullage and maximizing pressurant flow rate minimizes the mass of pressurant gas required to pressurize the tank. It is further demonstrated that proper dimensionless scaling of pressure and time permit all the pressure histories examined during this study to be displayed as a single curve.

  12. Transpiration Control Of Aerodynamics Via Porous Surfaces

    NASA Technical Reports Server (NTRS)

    Banks, Daniel W.; Wood, Richard M.; Bauer, Steven X. S.

    1993-01-01

    Quasi-active porous surface used to control pressure loading on aerodynamic surface of aircraft or other vehicle, according to proposal. In transpiration control, one makes small additions of pressure and/or mass to cavity beneath surface of porous skin on aerodynamic surface, thereby affecting rate of transpiration through porous surface. Porous skin located on forebody or any other suitable aerodynamic surface, with cavity just below surface. Device based on concept extremely lightweight, mechanically simple, occupies little volume in vehicle, and extremely adaptable.

  13. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    SciTech Connect

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heat release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  14. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    SciTech Connect

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heat release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  15. Predictions of entry heating for lower surface of shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Edwards, C. L. W.; Cole, S. R.

    1983-01-01

    A broad base of thermocouple and phase change paint data was assembled and correlated to the nominal design 14414.1 and proposed STS-1 (first flight of the space transportation system) entry trajectories. Averaged data from phase change paint tests compared favorably with thermocouple data for predicting heating rates. Laminar and turbulent radiation equilibrium heating rates were computed on the lower surface of the Shuttle orbiter for both trajectories, and the lower surface center line results were compared both with aerodynamic heating design data and with flight values from the STS-1 and STS-2 trajectories. The peak laminar heating values from the aerodynamic heating design data book were generally 40 to 60 percent higher than the laminar estimates of this study, except at the 55 percent location of maximum span where the design data book values were less than 10 percent higher. Estimates of both laminar and turbulent heating rates compared favorably with flight data.

  16. Heat dissipation of high rate Li-SOCl sub 2 primary cells

    NASA Astrophysics Data System (ADS)

    Cho, Y. I.; Halpert, G.; Deligiannis, E.

    1986-09-01

    The heat dissipation problem occurring in the lithium thionyl chloride cells discharged at relatively high rates under normal discharge conditions is examined. Four heat flow paths were identified, and the thermal resistances of the relating cell components along each flow path were accordingly calculated. From the thermal resistance network analysis, it was demonstrated that about 90 percent of the total heat produced within the cell should be dissipated along the radial direction in a spirally wound cell. In addition, the threshold value of the heat generation rate at which cell internal temperature could be maintained below 100 C, was calculated from total thermal resistance and found to be 2.9 W. However, these calculations were made only at the cell components' level, and the transient nature of the heat accumulation and dissipation was not considered. A simple transient model based on the lumped-heat-capacity concept was developed to predict the time-dependent cell temperature at different discharge rates. The overall objective was to examine the influence of cell design variable from the heat removal point of view under normal discharge conditions and to make recommendations to build more efficient lithium cells.

  17. Does attenuated skin blood flow lower sweat rate and the critical environmental limit for heat balance during severe heat exposure?

    PubMed

    Cramer, Matthew N; Gagnon, Daniel; Crandall, Craig G; Jay, Ollie

    2017-02-01

    What is the central question of this study? Does attenuated skin blood flow diminish sweating and reduce the critical environmental limit for heat balance, which indicates maximal heat loss potential, during severe heat stress? What is the main finding and its importance? Isosmotic hypovolaemia attenuated skin blood flow by ∼20% but did not result in different sweating rates, mean skin temperatures or critical environmental limits for heat balance compared with control and volume-infusion treatments, suggesting that the lower levels of skin blood flow commonly observed in aged and diseased populations may not diminish maximal whole-body heat dissipation. Attenuated skin blood flow (SkBF) is often assumed to impair core temperature (Tc ) regulation. Profound pharmacologically induced reductions in SkBF (∼85%) lead to impaired sweating, but whether the smaller attenuations in SkBF (∼20%) more often associated with ageing and certain diseases lead to decrements in sweating and maximal heat loss potential is unknown. Seven healthy men (28 ± 4 years old) completed a 30 min equilibration period at 41°C and a vapour pressure (Pa ) of 2.57 kPa followed by incremental steps in Pa of 0.17 kPa every 6 min to 5.95 kPa. Differences in heat loss potential were assessed by identifying the critical vapour pressure (Pcrit ) at which an upward inflection in Tc occurred. The following three separate treatments elicited changes in plasma volume to achieve three distinct levels of SkBF: control (CON); diuretic-induced isosmotic dehydration to lower SkBF (DEH); and continuous saline infusion to maintain SkBF (SAL). The Tc , mean skin temperature (Tsk ), heart rate, mean laser-Doppler flux (forearm and thigh; LDFmean ), mean local sweat rate (forearm and thigh; LSRmean ) and metabolic rate were measured. In DEH, a 14.2 ± 5.7% lower plasma volume resulted in a ∼20% lower LDFmean in perfusion units (PU) (DEH, 139 ± 23 PU; CON, 176 ± 22 PU; and SAL, 186 ± 22

  18. The Effect of Heat Treatments and Coatings on the Outgassing Rate of Stainless Steel Chambers

    SciTech Connect

    Mamum, Md Abdullah A.; Elmustafa, Abdelmageed A,; Stutzman, Marcy L.; Adderley, Philip A.; Poelker, Matthew

    2014-03-01

    The outgassing rates of four nominally identical 304L stainless steel vacuum chambers were measured to determine the effect of chamber coatings and heat treatments. One chamber was coated with titanium nitride (TiN) and one with amorphous silicon (a-Si) immediately following fabrication. One chamber remained uncoated throughout, and the last chamber was first tested without any coating, and then coated with a-Si following a series of heat treatments. The outgassing rate of each chamber was measured at room temperatures between 15 and 30 deg C following bakes at temperatures between 90 and 400 deg C. Measurements for bare steel showed a significant reduction in the outgassing rate by more than a factor of 20 after a 400 deg C heat treatment (3.5 x 10{sup 12} TorrL s{sup -1}cm{sup -2} prior to heat treatment, reduced to 1.7 x 10{ sup -13} TorrL s{sup -1}cm{sup -2} following heat treatment). The chambers that were coated with a-Si showed minimal change in outgassing rates with heat treatment, though an outgassing rate reduced by heat treatments prior to a-Si coating was successfully preserved throughout a series of bakes. The TiN coated chamber exhibited remarkably low outgassing rates, up to four orders of magnitude lower than the uncoated stainless steel. An evaluation of coating composition suggests the presence of elemental titanium which could provide pumping and lead to an artificially low outgassing rate. The outgassing results are discussed in terms of diffusion-limited versus recombination-limited processes.

  19. Assessment of CFD Hypersonic Turbulent Heating Rates for Space Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Wood, William A.; Oliver, A. Brandon

    2011-01-01

    Turbulent CFD codes are assessed for the prediction of convective heat transfer rates at turbulent, hypersonic conditions. Algebraic turbulence models are used within the DPLR and LAURA CFD codes. The benchmark heat transfer rates are derived from thermocouple measurements of the Space Shuttle orbiter Discovery windward tiles during the STS-119 and STS-128 entries. The thermocouples were located underneath the reaction-cured glass coating on the thermal protection tiles. Boundary layer transition flight experiments conducted during both of those entries promoted turbulent flow at unusually high Mach numbers, with the present analysis considering Mach 10{15. Similar prior comparisons of CFD predictions directly to the flight temperature measurements were unsatisfactory, showing diverging trends between prediction and measurement for Mach numbers greater than 11. In the prior work, surface temperatures and convective heat transfer rates had been assumed to be in radiative equilibrium. The present work employs a one-dimensional time-accurate conduction analysis to relate measured temperatures to surface heat transfer rates, removing heat soak lag from the flight data, in order to better assess the predictive accuracy of the numerical models. The turbulent CFD shows good agreement for turbulent fuselage flow up to Mach 13. But on the wing in the wake of the boundary layer trip, the inclusion of tile conduction effects does not explain the prior observed discrepancy in trends between simulation and experiment; the flight heat transfer measurements are roughly constant over Mach 11-15, versus an increasing trend with Mach number from the CFD.

  20. Thermomagnetic behavior of magnetic susceptibility - heating rate and sample size effects

    NASA Astrophysics Data System (ADS)

    Jordanova, Diana; Jordanova, Neli

    2015-12-01

    Thermomagnetic analysis of magnetic susceptibility k(T) was carried out for a number of natural powder materials from soils, baked clay and anthropogenic dust samples using fast (11oC/min) and slow (6.5oC/min) heating rates available in the furnace of Kappabridge KLY2 (Agico). Based on the additional data for mineralogy, grain size and magnetic properties of the studied samples, behaviour of k(T) cycles and the observed differences in the curves for fast and slow heating rate are interpreted in terms of mineralogical transformations and Curie temperatures (Tc). The effect of different sample size is also explored, using large volume and small volume of powder material. It is found that soil samples show enhanced information on mineralogical transformations and appearance of new strongly magnetic phases when using fast heating rate and large sample size. This approach moves the transformation at higher temperature, but enhances the amplitude of the signal of newly created phase. Large sample size gives prevalence of the local micro- environment, created by evolving gases, released during transformations. The example from archeological brick reveals the effect of different sample sizes on the observed Curie temperatures on heating and cooling curves, when the magnetic carrier is substituted magnetite (Mn0.2Fe2.70O4). Large sample size leads to bigger differences in Tcs on heating and cooling, while small sample size results in similar Tcs for both heating rates.

  1. The Effect of Particle Concentration on the Heating Rate of Ferrofluids for Magnetic Hyperthermia

    NASA Astrophysics Data System (ADS)

    Malaescu, I.; Marin, C. N.; Bunoiu, M.; Fannin, P. C.; Stefu, N.; Iordaconiu, L.

    2015-12-01

    The complex magnetic susceptibility χ(f) = χ'(f) - i χ″(f), of a ferrofluid sample with magnetite particles dispersed in kerosene and stabilized with oleic acid, over the range 0.1 GHz to 6 GHz, was determined. The initial sample has been successively diluted with kerosene (with a dilution rate of 2/3), thus obtaining further three samples. Using the complex magnetic susceptibility measurements of each sample, the frequency field and particle concentration dependencies of the heating rate of the ferrofluid samples, were analyzed. The results show the possibility of using the heating rate of ferrofluid samples with different particle concentrations, in hyperthermia applications.

  2. Evaluating ventilation rates based on new heat and moisture production data for swine production

    USDA-ARS?s Scientific Manuscript database

    Heat and moisture production (HMP) rates of animals are used for calculation of ventilation rate (VR) in animal housing. New swine HMP data revealed considerable differences from previously reported data. This project determined new design VR and evaluated differences from previously recommended VRs...

  3. On the increase in rate of heat production caused by stretch in frog's skeletal muscle

    PubMed Central

    Clinch, N. F.

    1968-01-01

    1. The increase in rate of heat production caused by stretch in the unstimulated frog's sartorius (stretch response) has been measured using a conventional thermopile technique. 2. The rate of heat production was found constant between l0 (the distance in vivo between the tendons when the legs were in a straight line) and 1·2 l0, and rose rapidly above this length to reach 3-5 times the basal rate at 1·3 l0. Stretching to greater lengths appeared to damage the muscles. 3. The stretch response is increased by several substances which increase the duration of the active state. 4. Unlike the rate of heat production at l0, the stretch response is increased by procaine; while the presence of CO2 greatly reduces it. 5. Evidence is presented supporting the hypothesis that the stretch response is associated with the appearance of tension in the sarcolemma. ImagesFig. 2 PMID:5652883

  4. Distributed measurement of flow rate in conduits using heated fiber optic distributed temperature sensing

    NASA Astrophysics Data System (ADS)

    Sánchez, Raúl; Zubelzu, Sergio; Rodríguez-Sinobas, Leonor; Juana, Luis

    2016-04-01

    In some cases flow varies along conduits, such as in irrigated land drainage pipes and channels, irrigation laterals and others. Detailed knowledge of flow rate along the conduit makes possible analytical evaluation of water distribution and collection systems performance. Flow rate can change continuously in some systems, like in drainage pipes and channels, or abruptly, like in conduits bifurcations or emitter insertions. A heat pulse along the conduit makes possible to get flow rate from continuity and heat balance equations. Due to the great value of specific heat of water, temperature changes along conduit are smaller than the noise that involves the measurement process. This work presents a methodology that, dealing with the noise of distributed temperature measurements, leads to flow rate determination along pressurized pipes or open channel flows.

  5. A novel setup for wafer curvature measurement at very high heating rates.

    PubMed

    Islam, T; Zechner, J; Bernardoni, M; Nelhiebel, M; Pippan, R

    2017-02-01

    The curvature evolution of a thin film layer stack containing a top Al layer is measured during temperature cycles with very high heating rates. The temperature cycles are generated by means of programmable electrical power pulses applied to miniaturized polysilicon heater systems embedded inside a semiconductor chip and the curvature is measured by a fast wafer curvature measurement setup. Fast temperature cycles with heating duration of 100 ms are created to heat the specimen up to 270 °C providing an average heating rate of 2500 K/s. As a second approach, curvature measurement utilizing laser scanning Doppler vibrometry is also demonstrated which verifies the results obtained from the fast wafer curvature measurement setup. Film stresses calculated from the measured curvature values compare well to literature results, indicating that the new method can be used to measure curvature during fast temperature cycling.

  6. A novel setup for wafer curvature measurement at very high heating rates

    NASA Astrophysics Data System (ADS)

    Islam, T.; Zechner, J.; Bernardoni, M.; Nelhiebel, M.; Pippan, R.

    2017-02-01

    The curvature evolution of a thin film layer stack containing a top Al layer is measured during temperature cycles with very high heating rates. The temperature cycles are generated by means of programmable electrical power pulses applied to miniaturized polysilicon heater systems embedded inside a semiconductor chip and the curvature is measured by a fast wafer curvature measurement setup. Fast temperature cycles with heating duration of 100 ms are created to heat the specimen up to 270 °C providing an average heating rate of 2500 K/s. As a second approach, curvature measurement utilizing laser scanning Doppler vibrometry is also demonstrated which verifies the results obtained from the fast wafer curvature measurement setup. Film stresses calculated from the measured curvature values compare well to literature results, indicating that the new method can be used to measure curvature during fast temperature cycling.

  7. Peregrine Rocket Motor Test at the Ames Outdoor Aerodynamic Rese

    NASA Image and Video Library

    2017-02-15

    Ashley Karp, NASA JPL (Left) and Hunjoo Kim, NASA JPL (Right) attaching heat sensors the Peregrine Hybrid Rocket Engine prior to its test at the Outdoor Aerodynamic Research Facility (OARF, N-249) at NASA's Ames Research Center.

  8. Peregrine Rocket Motor Test at the Ames Outdoor Aerodynamic Rese

    NASA Image and Video Library

    2017-02-15

    Hunjoo Kim, NASA JPL (Left) and Ashley Karp, NASA JPL (Right) attaching heat sensors the Peregrine Hybrid Rocket Engine prior to its test at the Outdoor Aerodynamic Research Facility (OARF, N-249) at NASA’s Ames Research Center.

  9. Analysis of Heating Rates on the Conical Surface of Apollo Command Module Flying AS-202 Flight

    NASA Technical Reports Server (NTRS)

    Wong, Jim L.

    2005-01-01

    The aerodynamic and aerothermal heating at the leeward surfaces of the Apollo capsule flying high angle of attack were found difficult to simulate using conventional tools. Due to the large subsonic region in the proximity of the shoulder of the base shield, correlation-based tools were found to be inadequate. CFD tools are too time consuming for conceptual design purposes, and cannot account for the transient effects of material response such as wall temperature and blowing. An accurate and timely simulation is essential to effectively size the thermal protection system (TPS), to enhance its performance, and to ensure the safety of the crew. Northrop Grumman Corporation applied a modified version of the MASCC/ATAC program, an inviscid flowfield code with boundary layer solver to simulate this scenario. The MASCC/ATAC code is believed to be the only non-CFD code that can rigorously perform the simulations on the windward surface. The predictions on the windward side of the conical surface were found to be in good agreement with flight data over a wide range of environments. The results are presented in the paper.

  10. Effect of heating rate on the thermoluminescence and thermal properties of natural ulexite.

    PubMed

    Topaksu, M; Correcher, V; Garcia-Guinea, J; Yüksel, M

    2014-10-31

    Boron-rich compounds are of interest in the nuclear industry because they exhibit a high neutron absorption cross section. The manufacture of these materials involves the application of thermal and chemical treatments. This paper focuses on the study of the effect of the heating rate (HR) in two thermal techniques, differential thermal analysis (DTA) and thermoluminescence (TL), performed on natural ulexite from Bigadiç-Balıkesir (Turkey). The TL measurements were performed at six different heating rates in the range of 25-240°Cmin(-1). The UV-blue TL emission of natural ulexite shifted toward higher temperatures with increasing heating rate, whereas the intensity decreased. The kinetic parameters of the ulexite (Ea=0.65(9) eV and s=1.22×10(12)s(-1)) were calculated using the variable heating rate method. DTA measurements performed in the range of 0.5-10°Cmin(-1) displayed similar behavior to that of the TL response, despite the differences in technique and HR values. The DTA results indicated that natural ulexite exhibits two endothermic peaks originating from different processes: (i) a phase transition between the pentahydrated ulexite phase and a triple-hydrated phase and (ii) dehydration, dehydroxylation and alkali and earth-alkali self-diffusion processes in the ulexite lattice. The main endothermic peak shifted from 160°C to 250°C as the heating rate was increased.

  11. Pyrolysis polygeneration of poplar wood: Effect of heating rate and pyrolysis temperature.

    PubMed

    Chen, Dengyu; Li, Yanjun; Cen, Kehui; Luo, Min; Li, Hongyan; Lu, Bin

    2016-10-01

    The pyrolysis of poplar wood were comprehensively investigated at different pyrolysis temperatures (400, 450, 500, 550, and 600°C) and at different heating rates (10, 30, and 50°C/min). The results showed that BET surface area of biochar, the HHV of non-condensable gas and bio-oil reached the maximum values of 411.06m(2)/g, 14.56MJ/m(3), and 14.39MJ/kg, under the condition of 600°C and 30°C/min, 600°C and 50°C/min, and 550°C and 50°C/min, respectively. It was conducive to obtain high mass and energy yield of bio-oil at 500°C and higher heating rate, while lower pyrolysis temperature and heating rate contributed towards obtaining both higher mass yield and energy yield of biochar. However, higher pyrolysis temperature and heating rate contributed to obtain both higher mass yield and energy yield of the non-condensable gas. In general, compared to the heating rate, the pyrolysis temperature had more effect on the product properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Selection, Evaluation, and Rating of Compact Heat Exchangers v. 1.006

    SciTech Connect

    Carlson, Matthew D.

    2016-11-09

    SEARCH determines and optimizes the design of a compact heat exchanger for specified process conditions. The user specifies process boundary conditions including the fluid state and flow rate and SEARCH will determine the optimum flow arrangement, channel geometry, and mechanical design for the unit. Fluids are modeled using NIST Refprop or tabulated values. A variety of thermal-hydraulic correlations are available including user-defined equations to accurately capture the heat transfer and pressure drop behavior of the process flows.

  13. Determination of Kinetic Parameters for Thermal Decomposition of Phenolic Ablative Materials by Multiple Heating Rate Method

    DTIC Science & Technology

    1980-07-01

    the ratio method to analyze thermogravimetric data obtained for a urethane polymer. Baer, Hedges, Seader , Jayakar, and Wojcik6 heated samples of...reinforced polymers at heating rates up to 4200°C/min. The data were correlated by a numerical technique developed by Burningham and Seader .7 Friedman...Decomposition Through Thermogravimetric Analysis," Thermochimica Acta, No, 1, (1970), pp. 147-158. 6. A. D. Baer, J. H. Hedges, J. D. Seader , K. M. Jayakar

  14. Effects of whole body heating on dynamic baroreflex regulation of heart rate in humans

    NASA Technical Reports Server (NTRS)

    Crandall, C. G.; Zhang, R.; Levine, B. D.

    2000-01-01

    The purpose of this project was to identify whether dynamic baroreflex regulation of heart rate (HR) is altered during whole body heating. In 14 subjects, dynamic baroreflex regulation of HR was assessed using transfer function analysis. In normothermic and heat-stressed conditions, each subject breathed at a fixed rate (0. 25 Hz) while beat-by-beat HR and systolic blood pressure (SBP) were obtained. Whole body heating significantly increased sublingual temperature, HR, and forearm skin blood flow. Spectral analysis of HR and SBP revealed that the heat stress significantly reduced HR and SBP variability within the high-frequency range (0.2-0.3 Hz), reduced SBP variability within the low-frequency range (0.03-0.15 Hz), and increased the ratio of low- to high-frequency HR variability (all P < 0.01). Transfer function gain analysis showed that the heat stress reduced dynamic baroreflex regulation of HR within the high-frequency range (from 1.04 +/- 0.06 to 0.54 +/- 0.6 beats. min(-1). mmHg(-1); P < 0.001) without significantly affecting the gain in the low-frequency range (P = 0.63). These data suggest that whole body heating reduced high-frequency dynamic baroreflex regulation of HR associated with spontaneous changes in blood pressure. Reduced vagal baroreflex regulation of HR may contribute to reduced orthostatic tolerance known to occur in humans during heat stress.

  15. Effects of whole body heating on dynamic baroreflex regulation of heart rate in humans

    NASA Technical Reports Server (NTRS)

    Crandall, C. G.; Zhang, R.; Levine, B. D.

    2000-01-01

    The purpose of this project was to identify whether dynamic baroreflex regulation of heart rate (HR) is altered during whole body heating. In 14 subjects, dynamic baroreflex regulation of HR was assessed using transfer function analysis. In normothermic and heat-stressed conditions, each subject breathed at a fixed rate (0. 25 Hz) while beat-by-beat HR and systolic blood pressure (SBP) were obtained. Whole body heating significantly increased sublingual temperature, HR, and forearm skin blood flow. Spectral analysis of HR and SBP revealed that the heat stress significantly reduced HR and SBP variability within the high-frequency range (0.2-0.3 Hz), reduced SBP variability within the low-frequency range (0.03-0.15 Hz), and increased the ratio of low- to high-frequency HR variability (all P < 0.01). Transfer function gain analysis showed that the heat stress reduced dynamic baroreflex regulation of HR within the high-frequency range (from 1.04 +/- 0.06 to 0.54 +/- 0.6 beats. min(-1). mmHg(-1); P < 0.001) without significantly affecting the gain in the low-frequency range (P = 0.63). These data suggest that whole body heating reduced high-frequency dynamic baroreflex regulation of HR associated with spontaneous changes in blood pressure. Reduced vagal baroreflex regulation of HR may contribute to reduced orthostatic tolerance known to occur in humans during heat stress.

  16. Ammonium perchlorate gasification and combustion at high heating rates and low pressures.

    NASA Technical Reports Server (NTRS)

    Pellett, G. L.

    1973-01-01

    Mass-spectrometric and linear regression rate characterizations are reported, derived from CO2 laser pyrolyses of pressed NH2ClO4 (AP) at incident heat fluxes ranging from 25 to 4000 cal/sq cm sec. Product evolution-rate histories were obtained in vacuo by time-resolved (5 msec) mass spectrometry during (1) transient heat-up, and (2) subsequent quasi-steady vaporization (QSV). Vaporization induction times were obtained for (1); these, coupled with heat-transfer approximations neglecting thermochemical heat release, indicated that optical absorption at 10.6 microns dominated over conduction for heat fluxes much greater than 300. Conclusions applying in vacuo were: preferential desorption of NH3, with net accumulation of adsorbed HClO4, occurred during transient heat-up and onset of condensed phase decomposition (CPD), but preferential decomposition of adsorbed HClO4 (compared to NH3) occurred during QSV when CPD was significant. CPD was the dominant mode of QSV at moderate heat fluxes.

  17. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    DOE PAGES

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heatmore » release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  18. Aerodynamic performance of centrifugal compressors

    SciTech Connect

    Sayyed, S.

    1981-12-01

    Saving money with an efficient pipeline system design depends on accurately predicting compressor performance and ensuring that it meets the manufacturer's guaranteed levels. When shop testing with the actual gas is impractical, an aerodynamic test can ascertain compressor efficiency, but the accuracy and consistency of data acquisition in such tests is critical. Low test-pressure levels necessitate accounting for the effects of Reynolds number and heat transfer. Moreover, the compressor user and manufacturer must agree on the magnitude of the corrections to be applied to the test data.

  19. Atomic oxygen, atomic hydrogen, and chemical heating rates derived from SABER

    NASA Astrophysics Data System (ADS)

    Mlynczak, M. G.

    The SABER instrument on the TIMED satellite measures the infrared OH airglow at 2.0 um in the terrestrial mesosphere. These measurements are inverted to provide the volume emissions rates of the OH(9-7 + 8-6) bands. These high-lying bands are formed directly upon the reaction of atomic hydrogen and ozone and thus the measured volume emission rate is a direct measure of the rate of reaction. The SABER OH emission rates and the measured SABER ozone are used to derive the concentration of atomic hydrogen in the mesopause region. The emission rate is also a direct measure of the rate of energy deposition due to the reaction of atomic hydrogen and ozone. Rates of chemical heating are then readily derived upon provision of atmospheric temperature and density from SABER. Under the assumption of photochemical steady state in the production and loss of ozone, the emission rates can also be used to derive atomic oxygen. The abundances of H and O enable the computation of rates of chemical heating due to numerous exothermic reactions. A key to these derivations lies in the knowledge of the rate of quenching/reaction of vibrationally excited OH with atomic oxygen. We present the SABER airglow models, data inversion approach, and results for O, H, and chemical heating.

  20. Uncertainty in Computational Aerodynamics

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.; Hemsch, M. J.; Morrison, J. H.

    2003-01-01

    An approach is presented to treat computational aerodynamics as a process, subject to the fundamental quality assurance principles of process control and process improvement. We consider several aspects affecting uncertainty for the computational aerodynamic process and present a set of stages to determine the level of management required to meet risk assumptions desired by the customer of the predictions.

  1. Unsteady transonic aerodynamics

    SciTech Connect

    Nixon, D.

    1989-01-01

    Various papers on unsteady transonic aerodynamics are presented. The topics addressed include: physical phenomena associated with unsteady transonic flows, basic equations for unsteady transonic flow, practical problems concerning aircraft, basic numerical methods, computational methods for unsteady transonic flows, application of transonic flow analysis to helicopter rotor problems, unsteady aerodynamics for turbomachinery aeroelastic applications, alternative methods for modeling unsteady transonic flows.

  2. Uncertainty in Computational Aerodynamics

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.; Hemsch, M. J.; Morrison, J. H.

    2003-01-01

    An approach is presented to treat computational aerodynamics as a process, subject to the fundamental quality assurance principles of process control and process improvement. We consider several aspects affecting uncertainty for the computational aerodynamic process and present a set of stages to determine the level of management required to meet risk assumptions desired by the customer of the predictions.

  3. Computation of dragonfly aerodynamics

    NASA Astrophysics Data System (ADS)

    Gustafson, Karl; Leben, Robert

    1991-04-01

    Dragonflies are seen to hover and dart, seemingly at will and in remarkably nimble fashion, with great bursts of speed and effectively discontinuous changes of direction. In their short lives, their gossamer flight provides us with glimpses of an aerodynamics of almost extraterrestrial quality. Here we present the first computer simulations of such aerodynamics.

  4. Numerical Aerodynamic Simulation

    NASA Technical Reports Server (NTRS)

    1989-01-01

    An overview of historical and current numerical aerodynamic simulation (NAS) is given. The capabilities and goals of the Numerical Aerodynamic Simulation Facility are outlined. Emphasis is given to numerical flow visualization and its applications to structural analysis of aircraft and spacecraft bodies. The uses of NAS in computational chemistry, engine design, and galactic evolution are mentioned.

  5. Rapid calculation of radiative heating rates and photodissociation rates in inhomogeneous multiple scattering atmospheres

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.; Mckay, C. P.; Ackerman, T. P.; Santhanam, K.

    1989-01-01

    The solution of the generalized two-stream approximation for radiative transfer in homogeneous multiple scattering atmospheres is extended to vertically inhomogeneous atmospheres in a manner which is numerically stable and computationally efficient. It is shown that solar energy deposition rates, photolysis rates, and infrared cooling rates all may be calculated with the simple modifications of a single algorithm. The accuracy of the algorithm is generally better than 10 percent, so that other uncertainties, such as in absorption coefficients, may often dominate the error in calculation of the quantities of interest to atmospheric studies.

  6. Aerodynamic Temperature Derived from Flux-Profile Measurements and Two-Source Model Predictions over a Cotton Row Crop in an Advective Environment

    USDA-ARS?s Scientific Manuscript database

    The surface aerodynamic temperature (SAT) is related to the atmospheric forcing conditions (radiation, wind speed and air temperature) and surface conditions. SAT is required in the bulk surface resistance equation to calculate the rate of sensible heat flux exchange. SAT cannot be measured directly...

  7. Iced-airfoil aerodynamics

    NASA Astrophysics Data System (ADS)

    Bragg, M. B.; Broeren, A. P.; Blumenthal, L. A.

    2005-07-01

    Past research on airfoil aerodynamics in icing are reviewed. This review emphasizes the time period after the 1978 NASA Lewis workshop that initiated the modern icing research program at NASA and the current period after the 1994 ATR accident where aerodynamics research has been more aircraft safety focused. Research pre-1978 is also briefly reviewed. Following this review, our current knowledge of iced airfoil aerodynamics is presented from a flowfield-physics perspective. This article identifies four classes of ice accretions: roughness, horn ice, streamwise ice, and spanwise-ridge ice. For each class, the key flowfield features such as flowfield separation and reattachment are discussed and how these contribute to the known aerodynamic effects of these ice shapes. Finally Reynolds number and Mach number effects on iced-airfoil aerodynamics are summarized.

  8. The effect of fire retardants on the heat-release rate of building materials

    NASA Astrophysics Data System (ADS)

    Martin, S. B.; Inman, L. B.

    1981-07-01

    A method was developed for making up thick cellulosic specimens with thermocouples implanted at various depths to determine the time dependent temperature profiles when exposed to external radiant fluxes. Specimens of alpha cellulose, both untreated and treated with 2 percent by weight of Na2B4O7, were exposed to an applied radiant flux of 3.7 W/sq cm in the heat release rate calorimeter in order to examine the effect of the fire retardants on the heat release rate. The results on a limited number of tests suggest that the char enhancement, produced by the presence of Na2B4O7, reduces the heat release rate mainly by the reduction of the caloric value of the volatile products rather than by the insulating effect of the increased char layer thickness.

  9. Molecular dynamics simulations of aggregation of copper nanoparticles with different heating rates

    NASA Astrophysics Data System (ADS)

    Li, Qibin; Wang, Meng; Liang, Yunpei; Lin, Liyang; Fu, Tao; Wei, Peitang; Peng, Tiefeng

    2017-06-01

    Molecular dynamics simulations were employed to investigate the heating rates' effect on aggregation of two copper nanoparticles. The aggregation can be distinguished into three distinct regimes by the contacting and melting of nanoparticles. The nanoparticles contacting at a lower temperature during the sintering with lower heating rate, meanwhile, some temporary stacking fault exists at the contacting neck. The aggregation properties of the system, i.e. neck diameter, shrinkage ratio, potential energy, mean square displacement (MSD) and relative gyration radius, experience drastic changes due to the free surface annihilation. After the nanoparticles coalesced for a stable period, the shrinkage ratio, MSD, relative gyration radius and neck diameter of the system are dramatically changed during the melting process. It is shown that the shrinkage ratio and MSD have relative larger increasing ratio for a lower heating rate. While the evolution of the relative gyration radius and neck diameter is only sensitive to the temperature.

  10. On the effect of marangoni flow on evaporation rates of heated water drops.

    PubMed

    Girard, F; Antoni, M; Sefiane, K

    2008-09-02

    In this letter we show that the Marangoni flow contribution to the evaporation rate of small heated water droplets resting on hot substrates is negligible. We compare data of evaporating droplet experiments with numerical results and assess the effect of Marangoni flow and its contribution to the evaporation process. We demonstrate that heat conduction inside these water droplets is sufficient to give an accurate estimate of evaporation rates. Although convection in evaporating water droplets remains an open problem, our aim in this study is to demonstrate that these effects can be neglected in the investigation of evaporation rate evaluation. It is worth noting that the presented results apply to volatile heated drops which might differ from spontaneously evaporating cases.

  11. Effects of heating rate on slow pyrolysis behavior, kinetic parameters and products properties of moso bamboo.

    PubMed

    Chen, Dengyu; Zhou, Jianbin; Zhang, Qisheng

    2014-10-01

    Effects of heating rate on slow pyrolysis behaviors, kinetic parameters, and products properties of moso bamboo were investigated in this study. Pyrolysis experiments were performed up to 700 °C at heating rates of 5, 10, 20, and 30 °C/min using thermogravimetric analysis (TGA) and a lab-scale fixed bed pyrolysis reactor. The results show that the onset and offset temperatures of the main devolatilization stage of thermogravimetry/derivative thermogravimetry (TG/DTG) curves obviously shift toward the high-temperature range, and the activation energy values increase with increasing heating rate. The heating rate has different effects on the pyrolysis products properties, including biochar (element content, proximate analysis, specific surface area, heating value), bio-oil (water content, chemical composition), and non-condensable gas. The solid yields from the fixed bed pyrolysis reactor are noticeably different from those of TGA mainly because the thermal hysteresis of the sample in the fixed bed pyrolysis reactor is more thorough.

  12. Shortwave radiative heating rate profiles in hazy and clear atmosphere: a sensitivity study

    NASA Astrophysics Data System (ADS)

    Doppler, Lionel; Fischer, Jürgen; Ravetta, François; Pelon, Jacques; Preusker, René

    2010-05-01

    Aerosols have an impact on shortwave heating rate profiles (additional heating or cooling). In this survey, we quantify the impact of several key-parameters on the heating rate profiles of the atmosphere with and without aerosols. These key-parameters are: (1) the atmospheric model (tropical, midlatitude summer or winter, US Standard), (2) the integrated water vapor amount (IWV ), (3) the ground surface (flat and rough ocean, isotropic surface albedo for land), (4) the aerosol composition (dusts, soots or maritimes mixtures with respect to the OPAC-database classification), (5) the aerosol optical depth and (6) vertical postion, and (7) the single-scattering albedo (?o) of the aerosol mixture. This study enables us to evaluate which parameters are most important to take into account in a radiative energy budget of the atmosphere and will be useful for a future study: the retrieval of heating rates profiles from satellite data (CALIPSO, MODIS, MERIS) over the Mediterranean Sea. All the heating rates are computed by using the vector irradiances computed at each pressure level in the spectral interval 0.2 - 3.6μm (shortwave) by the 1D radiative transfer model for atmosphere and ocean: MOMO (Matrix-Operator MOdel) of the Institute for Space Science, FU Berlin 1

  13. Across- and within-session variability of ratings of painful contact heat stimuli

    PubMed Central

    Quiton, Raimi L.; Greenspan, Joel D.

    2016-01-01

    This study examined within- and across-session consistency of visual analog scale (VAS) pain intensity and unpleasantness ratings of contact heat stimuli in 64 subjects (32 male). Subjects participated in four sessions over 14 days, with three stimulus series per session. Two levels of painful heat (pain-lo: rated 40, and pain-hi: rated 70 on a 0–100 VAS) were delivered in randomized order during each series, with temperatures selected on an individual subject basis to equalize pain perception across subjects. Across-session ratings declined by the fourth session for both pain levels (p=0.01). Within-session ratings declined by the third series for both pain levels (p<0.001). While significant, changes in across- and within-session ratings were of small magnitude. Comparison of coefficients of variation (CV) for across- and within-session ratings revealed that pain-lo ratings were more variable than pain-hi ratings (p<0.001). Across- and within-session CVs were highly correlated for each pain level (pain-lo p<0.001; pain-hi p=0.001), suggesting that variability of VAS ratings is a characteristic of individual subjects over both short and long time scales. Across- and within-session CVs were significantly negatively correlated with individual ratings of the stimuli, but were not correlated with demographic or psychosocial factors. Furthermore, sex did not impact consistency of ratings, demonstrating that neither sex is more variable in ratings than the other over time. Taken together, these findings suggest that VAS ratings of painful contact heat are relatively stable over time but the variability of these ratings is significantly impacted by the perceived intensity of the stimulus. PMID:17942227

  14. Heat and water rate transfer processes in the human respiratory tract at various altitudes.

    PubMed

    Kandjov, I M

    2001-02-01

    The process of the respiratory air conditioning as a process of heat and mass exchange at the interface inspired air-airways surface was studied. Using a model of airways (Olson et al., 1970) where the segments of the respiratory tract are like cylinders with a fixed length and diameter, the corresponding heat transfer equations, in the paper are founded basic rate exchange parameters-convective heat transfer coefficient h(c)(W m(-2) degrees C(-1)) and evaporative heat transfer coefficient h(e)(W m(-2)hPa(-1)). The rate transfer parameters assumed as sources with known heat power are connected to airflow rate in different airways segments. Relationships expressing warming rate of inspired air due to convection, warming rate of inspired air due to evaporation, water diffused in the inspired air from the airways wall, i.e. a system of air conditioning parameters, was composed. The altitude dynamics of the relations is studied. Every rate conditioning parameter is an increasing function of altitude. The process of diffusion in the peripheral bronchial generations as a basic transfer process is analysed. The following phenomenon is in effect: the diffusion coefficient increases with altitude and causes a compensation of simultaneous decreasing of O(2)and CO(2)densities in atmospheric air. Due to this compensation, the diffusion in the peripheral generations with altitude is approximately constant. The elements of the human anatomy optimality as well as the established dynamics are discussed and assumed. The square form of the airways after the trachea expressed in terms of transfer supposes (in view of maximum contact surface), that a maximum heat and water exchange is achieved, i.e. high degree of air condition at fixed environmental parameters and respiration regime.

  15. Inverse bremsstrahlung heating rate in xenon clusters in the eikonal approximation

    SciTech Connect

    Dey, R.; Roy, A. C.

    2013-03-15

    We report inverse bremsstrahlung (IB) heating rates in the eikonal approximation (EA). The present analysis is performed using the plasma-screened Rogers and Debye potentials for Xe clusters with two different charge states (6 and 10). We compare the eikonal results with the first Born approximation (FBA) and classical-simulation (CL-sim) (Moll et al., Phys. Plasmas 19, 033303 (2012)) calculations for clusters in infrared light. Calculations have been performed for the field strength of 2.6 Multiplication-Sign 10{sup 8} V/cm. We find that compared to the FBA and CL-sim methods, the IB heating rate in the EA is less sensitive to the choice of the two potentials considered here. The present EA calculation shows that the influence of the inner structure of atomic ion on the heating rate is more prominent for the smaller ion charge (Xe{sup 6+}). In the case of low laser field approximation based on the elastic transport cross sections, it is seen that in contrast to the FBA and classical methods, the heating rate predicted by the EA does not deviate much all over the range of mean kinetic energy of electrons (20-500 eV) considered here for both the charge states of xenon (Xe{sup 6+} and Xe{sup 10+}). Furthermore, for the Rogers potential, EA is found to be in closer agreement with the classical method than the FBA. We also compare the results of the IB heating rate using the present and low-field approximation approaches to the above three methods and observe that the magnitudes of the IB heating rate calculated in the low field approximation are, in general, higher than the corresponding values predicted by the present approach for both the electron-ion potentials.

  16. Application of supercomputers to computational aerodynamics

    NASA Technical Reports Server (NTRS)

    Peterson, V. L.

    1984-01-01

    Computers are playing an increasingly important role in the field of aerodynamics such that they now serve as a major complement to wind tunnels in aerospace research and development. Factors pacing advances in computational aerodynamics are identified, including the amount of computational power required to take the next major step in the discipline. Example results obtained from the successively refined forms of the governing equations are discussed, both in the context of levels of computer power required and the degree to which they either further the frontiers of research or apply to problems of practical importance. Finally, the Numerical Aerodynamic Simulation (NAS) Program - with its 1988 target of achieving a sustained computational rate of 1 billion floating point operations per second and operating with a memory of 240 million words - is discussed in terms of its goals and its projected effect on the future of computational aerodynamics.

  17. Aerodynamics of a rolling airframe missile

    NASA Astrophysics Data System (ADS)

    Tisserand, L. E.

    1981-05-01

    For guidance-related reasons, there is considerable interest in rolling missiles having single-plane steering capability. To aid the aerodynamic design of these airframes, a unique investigation into the aerodynamics of a rolling, steering missile has been carried out. It represents the first known attempt to measure in a wind tunnel the aerodynamic forces and moments that act on a spinning body-canard-tail configuration that exercises canard steering in phase with body roll position. Measurements were made with the model spinning at steady-state roll rates ranging from 15 to 40 Hz over an angle-of-attack range up to about 16 deg. This short, exploratory investigation has demonstrated that a better understanding and a more complete definition of the aerodynamics of rolling, steering vehicles can be developed by way of simulative wind-tunnel testing.

  18. Interaction of Two Micro-slot Flames: Heat Release Rate and Flame Shape

    NASA Astrophysics Data System (ADS)

    Kuwana, K.; Kato, S.; Kosugi, A.; Hirasawa, T.; Nakamura, Y.

    2014-11-01

    This paper studies the interaction between two identical micro-slot diffusion flames. Here, we define a micro-slot flame as a slot flame of which the slot width is less than about 1 mm. Because of its smallness, a micro-slot flame has a high heating density and can be used as a small heat source. However, the heat release rate of a single micro-slot flame is limited, and therefore, multiple micro-slot flames may be used to increase total heat release rate. As a first step, this paper considers a situation in which two micro-slot flames are used with certain burner spacing. When two diffusion flames are placed closely, flame shape changes from that of an isolated flame. Studying such flame shape change and resultant change in total heat release rate is the topic of this paper. Experiment is conducted and total heat release rate is measured by integrating CH* chemiluminescence recorded using a CCD camera and an optical filter of the wavelength of 430 nm. Two different burner materials, copper and glass, are tested to study the effect of heat loss to burners. An analytical model is applied to predict flame shape. In addition to the classical Burke-Schumann assumptions, two slot flames are modeled as line sources with zero width, enabling a simple analytical solution for the critical burner spacing at which two flames touch each other. The critical burner spacing is a key parameter that characterizes the interaction between two micro-slot flames. Computational fluid dynamics (CFD) simulations are then conducted to test the validity of the present theory. CFD results are favorably compared with the theoretical prediction.

  19. A real-time heat strain risk classifier using heart rate and skin temperature.

    PubMed

    Buller, Mark J; Latzka, William A; Yokota, Miyo; Tharion, William J; Moran, Daniel S

    2008-12-01

    Heat injury is a real concern to workers engaged in physically demanding tasks in high heat strain environments. Several real-time physiological monitoring systems exist that can provide indices of heat strain, e.g. physiological strain index (PSI), and provide alerts to medical personnel. However, these systems depend on core temperature measurement using expensive, ingestible thermometer pills. Seeking a better solution, we suggest the use of a model which can identify the probability that individuals are 'at risk' from heat injury using non-invasive measures. The intent is for the system to identify individuals who need monitoring more closely or who should apply heat strain mitigation strategies. We generated a model that can identify 'at risk' (PSI 7.5) workers from measures of heart rate and chest skin temperature. The model was built using data from six previously published exercise studies in which some subjects wore chemical protective equipment. The model has an overall classification error rate of 10% with one false negative error (2.7%), and outperforms an earlier model and a least squares regression model with classification errors of 21% and 14%, respectively. Additionally, the model allows the classification criteria to be adjusted based on the task and acceptable level of risk. We conclude that the model could be a valuable part of a multi-faceted heat strain management system.

  20. Heating rates in furnace atomic absorption using the L'vov platform

    USGS Publications Warehouse

    Koirtyohann, S.R.; Giddings, R.C.; Taylor, H.E.

    1984-01-01

    Heating rate profiles for the furnace tube wall, the furnace atmosphere, and a L'vov platform were established for a range of conditions in a cyclically heated graphite atomizer. The tube wall profile was made by direct observation with a recording optical pyrometer. The sodium line reversal method was used to establish the heating rate of the furnace atmosphere, and appearance temperatures for a series metals of differing volatility was used to establish platform profiles. The tube wall heating rate was nearly linear at 2240??C s- until the desired temperature was reached after which the temperature remained constant. The furnace atmosphere reached a given temperature 0.2-0.4 s later than the tube wall through most of the atomize cycle. The platform lagged the tube wall 0.5-0.8 s. Under typical operating conditions the furnace atmosphere was 100-200??C cooler than the tube wall and at nearly constant temperature when the analyte vaporized from the platform. The L'vov platform causes the cyclically heated commercial furnace to approximate the behavior of a constant temperature furnace during atomization. ?? 1984.

  1. Phonatory aerodynamics in connected speech.

    PubMed

    Gartner-Schmidt, Jackie L; Hirai, Ryoji; Dastolfo, Christina; Rosen, Clark A; Yu, Lan; Gillespie, Amanda I

    2015-12-01

    1) Present phonatory aerodynamic data for healthy controls (HCs) in connected speech; 2) contrast these findings between HCs and patients with nontreated unilateral vocal fold paralysis (UVFP); 3) present pre- and post-vocal fold augmentation outcomes for patients with UVFP; 4) contrast data from patients with post-operative laryngeal augmentation to HCs. Retrospective, single-blinded. For phase I, 20 HC participants were recruited. For phase II, 20 patients with UVFP were age- and gender-matched to the 20 HC participants used in phase I. For phase III, 20 patients with UVFP represented a pre- and posttreatment cohort. For phase IV, 20 of the HC participants from phase I and 20 of the postoperative UVFP patients from phase III were used for direct comparison. Aerodynamic measures captured from a sample of the Rainbow Passage included: number of breaths, mean phonatory airflow rate, total duration of passage, inspiratory airflow duration, and expiratory airflow duration. The VHI-10 was also obtained pre- and postoperative laryngeal augmentation. All phonatory aerodynamic measures were significantly increased in patients with preoperative UVFP than the HC group. Patients with laryngeal augmentation took significantly less breaths, had less mean phonatory airflow rate during voicing, and had shorter inspiratory airflow duration than the preoperative UVFP group. None of the postoperative measures returned to HC values. Significant improvement in the Voice Handicap Index-10 scores postlaryngeal augmentation was also found. Methodology described in this study improves upon existing aerodynamic voice assessment by capturing characteristics germane to UVFP patient complaints and measuring change before and after laryngeal augmentation in connected speech. 4. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  2. Effect of static shape deformation on aerodynamics and aerothermodynamics of hypersonic inflatable aerodynamic decelerator

    NASA Astrophysics Data System (ADS)

    Guo, Jinghui; Lin, Guiping; Bu, Xueqin; Fu, Shiming; Chao, Yanmeng

    2017-07-01

    The inflatable aerodynamic decelerator (IAD), which allows heavier and larger payloads and offers flexibility in landing site selection at higher altitudes, possesses potential superiority in next generation space transport system. However, due to the flexibilities of material and structure assembly, IAD inevitably experiences surface deformation during atmospheric entry, which in turn alters the flowfield around the vehicle and leads to the variations of aerodynamics and aerothermodynamics. In the current study, the effect of the static shape deformation on the hypersonic aerodynamics and aerothermodynamics of a stacked tori Hypersonic Inflatable Aerodynamic Decelerator (HIAD) is demonstrated and analyzed in detail by solving compressible Navier-Stokes equations with Menter's shear stress transport (SST) turbulence model. The deformed shape is obtained by structural modeling in the presence of maximum aerodynamic pressure during entry. The numerical results show that the undulating shape deformation makes significant difference to flow structure. In particular, the more curved outboard forebody surface results in local flow separations and reattachments in valleys, which consequently yields remarkable fluctuations of surface conditions with pressure rising in valleys yet dropping on crests while shear stress and heat flux falling in valleys yet rising on crests. Accordingly, compared with the initial (undeformed) shape, the corresponding differences of surface conditions get more striking outboard, with maximum augmentations of 379 pa, 2224 pa, and 19.0 W/cm2, i.e., 9.8%, 305.9%, and 101.6% for the pressure, shear stress and heat flux respectively. Moreover, it is found that, with the increase of angle of attack, the aerodynamic characters and surface heating vary and the aeroheating disparities are evident between the deformed and initial shape. For the deformable HIAD model investigated in this study, the more intense surface conditions and changed flight

  3. R&D on Resistive Heat Exchangers for HTS High Rated Current Leads

    NASA Astrophysics Data System (ADS)

    Bi, Yanfang

    2011-12-01

    The HTS current leads of superconducting magnets for large scale fusion devices and high energy particle colliders can reduce the power consumption for cooling by 2/3 compared with conventional leads. The resistive sections of high-rated current leads are usually made of a heat exchanger cooled by gas flow. The supply of the cooling mass flow incurs more than 90% of the cooling cost for the HTS leads. The mass flow rate requirement depends not only on the length and material of the resistive heat exchanger, but also on the heat transfer coefficient and HEX surface, the joint resistance at the cold end and its cooling approach. The design and operation of a sheet-stack HEX with a larger specific surface and a much smaller hydraulic diameter are presented in the paper. The test results of an HTS lead optimized for 8 kA show that a 98.4% efficiency can be achieved.

  4. The effect of electrode surface roughness on the motional heating rate of electromagnetic trapped ions

    NASA Astrophysics Data System (ADS)

    Lin, Kuan-Yu; Low, Guang Hao; Chuang, Isaac

    Electric field noise is a major source of motional heating in trapped ion quantum computation. While it is well known that this noise is influenced by trap electrode geometry in patch potential and surface adsorbate models, this has only been analyzed for smooth surfaces. We investigate the dependence of electric field noise on the roughness of surface electrodes by deriving a Green's function describing this roughness, and evaluating its effects on adsorbate-surface binding energies. At cryogenic temperature, surface roughness is found to exponentially enhance or suppress heating rate, depending on the density distribution of surface adsorbates. Our result suggests that heating rates can be tuned over orders of magnitude by careful engineering of electrode surface profiles.

  5. Effect of surface catalytic activity on stagnation heat-transfer rates.

    NASA Technical Reports Server (NTRS)

    Anderson, L. A.

    1973-01-01

    An experiment was made to determine the effect heterogeneous catalytic surface reactions have on heat-transfer rates in highly frozen low-density stagnation-point boundary layers. Data were obtained in arc-heated facilities that were capable of producing large percentages of chemical energy frozen in a supersonic freestream. The heat-transfer rate to a silicon-dioxide surface was reduced to a minimum value of only one-third of the value obtained on relatively active nickel and platinum surfaces. This is the result of its low catalytic efficiency. Ionization energy was recovered on both the active and the inactive surfaces, indicating that this energy either was released many times faster than the recombination energy or was not controlled by the surface composition.

  6. Scattering rates and specific heat jumps in high-Tc cuprates

    NASA Astrophysics Data System (ADS)

    Storey, James

    Inspired by recent ARPES and tunneling studies on high-Tc cuprates, we examine the effect of a pair-breaking term in the self-energy on the shape of the electronic specific heat jump. It is found that the observed specific heat jump can be described in terms of a superconducting gap, that persists above the observed Tc, in the presence of a strongly temperature dependent pair-breaking scattering rate. An increase in the scattering rate is found to explain the non-BCS-like suppression of the specific heat jump with magnetic field. A discussion of these results in the context of other properties such as the superfluid density and Raman spectra will also be presented. Supported by the Marsden Fund Council from Government funding, administered by the Royal Society of New Zealand.

  7. Cloud properties and associated radiative heating rates in the tropical western Pacific

    SciTech Connect

    Mather, Jim H.; McFarlane, Sally A.; Miller, Mark A.; Johnson, Karen L.

    2007-03-01

    Radiative heating of the atmosphere affects cloud evolution on the cloud scale and it influences large-scale vertical motion. Obtaining good estimates of radiative heating rate profiles has been difficult due to a lack of cloud profile observations. The Atmospheric Radiation Measurement (ARM) program has been measuring cloud property distributions at sites around the globe including three in the tropical western Pacific (TWP) region. We have analyzed a month of these remote sensing observations at Manus and Nauru to calculate time series of vertical cloud property profiles and radiative heating rates. This data set will be an important tool for describing radiative processes in the tropics and assessing the simulation of these processes in dynamical models.

  8. Average Heating Rate of Hot Atmospheres in Distant Galaxy Clusters by Radio AGN: Evidence for Continuous AGN Heating

    NASA Astrophysics Data System (ADS)

    Ma, Cheng-Jiun; McNamara, B.; Nulsen, P.; Schaffer, R.

    2011-09-01

    X-ray observations of nearby clusters and galaxies have shown that energetic feedback from AGN is heating hot atmospheres and is probably the principal agent that is offsetting cooling flows. Here we examine AGN heating in distant X-ray clusters by cross correlating clusters selected from the 400 Square Degree X-ray Cluster survey with radio sources in the NRAO VLA Sky Survey. The jet power for each radio source was determined using scaling relations between radio power and cavity power determined for nearby clusters, groups, and galaxies with atmospheres containing X-ray cavities. Roughly 30% of the clusters show radio emission above a flux threshold of 3 mJy within the central 250 kpc that is presumably associated with the brightest cluster galaxy. We find no significant correlation between radio power, hence jet power, and the X-ray luminosities of clusters in redshift range 0.1 -- 0.6. The detection frequency of radio AGN is inconsistent with the presence of strong cooling flows in 400SD, but cannot rule out the presence of weak cooling flows. The average jet power of central radio AGN is approximately 2 10^{44} erg/s. The jet power corresponds to an average heating of approximately 0.2 keV/particle for gas within R_500. Assuming the current AGN heating rate remained constant out to redshifts of about 2, these figures would rise by a factor of two. Our results show that the integrated energy injected from radio AGN outbursts in clusters is statistically significant compared to the excess entropy in hot atmospheres that is required for the breaking of self-similarity in cluster scaling relations. It is not clear that central AGN in 400SD clusters are maintained by a self-regulated feedback loop at the base of a cooling flow. However, they may play a significant role in preventing the development of strong cooling flows at early epochs.

  9. Heat-rate improvements obtained by retubing condensers with new, enhanced tube types

    SciTech Connect

    Rabas, T.J.; Taborek, J.

    1995-01-01

    Significant fuel savings can be achieved at power plants by retubing the condensers with enhanced tubes. Because of the higher overall heat-transfer coefficient, the exhaust steam is condensed at a lower pressure and the plant efficiency is therefore increased or plant heat rate is reduced. Only the spirally indented type of enhanced tube is currently being used in the U.S. and most other countries; however, different types of enhanced tubes have been proposed for power-plant condensers, each with their own set of attributes. This paper determines what attributes and their magnitudes of enhanced tubes lead to the most energy savings as measured by reduction of the plant heat rate. The particular attributes considered are the inside and outside enhancement levels, the inside efficiency index (inside enhancement level divided by pressure-drop increase), and the enhanced-tube fouling-rate multiplier. Two particular condensers were selected because all necessary information were known from previous heat-rate studies such as the condenser geometry, the circulating-water pump and system information, and the low-pressure turbine characteristics. These are {open_quotes}real-world{close_quotes} condensers and therefore the finding will be representative for many other condenser-retubing applications. However, the authors strongly recommend that an economic evaluation be performed at each site to determine the energy savings and payback time. This generic investigation showed that the outside enhancement level is the most important attribute, and a value of about 1.5 can lead to heat-rate savings of about 20 to 40 Btu/kW-hr. Increasing the inside enhancement is less effective because of the increased pressure drop that leads to a reduction of the coolant flow rate and velocity.

  10. Aerodynamic preliminary analysis

    NASA Technical Reports Server (NTRS)

    Bonner, E.; Clever, W.; Divan, P.; Dunn, K.; Kojima, J.

    1981-01-01

    Computerization of aerodynamic theory has progressed to state where analysis of complete aircraft configurations can be performed in single program. Aerodynamic Preliminary Analysis System, APAS, is comprehensive aerodynamic analysis system, based on linearized potential theory. Three-dimensional configurations (with or without jet flaps) having multiple nonplanar surfaces of arbitrary planform and open or closed slender bodies of noncircular contour may be analyzed with APAS. As preliminary design aid, APAS allows designer to survey systematically large number of alternative configurations and component geometries economically.

  11. Effect of a finite ionization rate on the radiative heating of outer planet atmospheric entry probes

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1981-01-01

    The influence of finite rate ionization in the inviscid gas just behind the stagnation shock wave on the radiation heating of probes entering the hydrogen helium atmospere of the major planets was investigated. At the present time, there is disagreement as to whether the radiative flux increases or decreases relative to its equilibrium value when finite rate ionization is considered. Leibowitz and Kuo content that the finite rate ionization in the hydrogen gas just behind the shock wave reduces the radiative flux to the probe, whereas Tiwari and Szema predict that it increases the radiative flux. The radiation modeling used in the calculations of both pairs of these investigators was reviewed. It is concluded that finite rate ionization in the inviscid region of the shock layer should reduce the cold wall radiative heating below the values predicted by equilibrium chemistry assumptions.

  12. Heat and mass transfer rates during flow of dissociated hydrogen gas over graphite surface

    NASA Technical Reports Server (NTRS)

    Nema, V. K.; Sharma, O. P.

    1986-01-01

    To improve upon the performance of chemical rockets, the nuclear reactor has been applied to a rocket propulsion system using hydrogen gas as working fluid and a graphite-composite forming a part of the structure. Under the boundary layer approximation, theoretical predictions of skin friction coefficient, surface heat transfer rate and surface regression rate have been made for laminar/turbulent dissociated hydrogen gas flowing over a flat graphite surface. The external stream is assumed to be frozen. The analysis is restricted to Mach numbers low enough to deal with the situation of only surface-reaction between hydrogen and graphite. Empirical correlations of displacement thickness, local skin friction coefficient, local Nusselt number and local non-dimensional heat transfer rate have been obtained. The magnitude of the surface regression rate is found low enough to ensure the use of graphite as a linear or a component of the system over an extended period without loss of performance.

  13. Heat and mass transfer rates during flow of dissociated hydrogen gas over graphite surface

    NASA Technical Reports Server (NTRS)

    Nema, V. K.; Sharma, O. P.

    1986-01-01

    To improve upon the performance of chemical rockets, the nuclear reactor has been applied to a rocket propulsion system using hydrogen gas as working fluid and a graphite-composite forming a part of the structure. Under the boundary layer approximation, theoretical predictions of skin friction coefficient, surface heat transfer rate and surface regression rate have been made for laminar/turbulent dissociated hydrogen gas flowing over a flat graphite surface. The external stream is assumed to be frozen. The analysis is restricted to Mach numbers low enough to deal with the situation of only surface-reaction between hydrogen and graphite. Empirical correlations of displacement thickness, local skin friction coefficient, local Nusselt number and local non-dimensional heat transfer rate have been obtained. The magnitude of the surface regression rate is found low enough to ensure the use of graphite as a linear or a component of the system over an extended period without loss of performance.

  14. Evaluation of radiative heating rate profiles in eight GCMs using A-train satellite observations

    NASA Astrophysics Data System (ADS)

    Cesana, Gregory; Waliser, D. E.; L'Ecuyer, T.; Jiang, X.; Li, J.-L.

    2017-02-01

    In this study, we take advantage of two modeling experiments and A-train satellite observations to characterize the impact of cloud biases in the vertical distribution of radiative heating rates in eight general circulation models General Circulation Models (GCMs). We compare the modeled vertical distribution of clouds against the GCM-Oriented Cloud-Aerosols Lidar and Infrared Pathfinder Satellite Observations Cloud Product (CALIPSO-GOCCP) using a simulator approach. Although the overall pattern of modeled zonal cloud frequency profiles is relatively good (r=0.92 for the multi-model mean), we show two main systematic biases in the cloud frequency profiles: a positive bias above 7km (up to 10%), particularly in the tropics; and a negative bias below 3km (up to -10%), which reaches a maximum over the stratocumulus cloud regions. Using radiative heating rate profiles calculated with constraints from CloudSat, CALIPSO and other satellite observations, we show that the excess of clouds in the upper troposphere (>7km) results in excess infrared and solar heating in the vicinity of the clouds as well as more infrared heating for the entire column below the cloud. On the other hand, the lack of clouds in the lower troposphere reduces the infrared cooling near the missing cloud levels and increases the absorption of solar radiation by water vapor below. The global radiative heating rate between 50°S and 50°N is too warm in the models (-0.81K/day vs. -1.01K/day). The representation of clouds in GCMs remains challenging, but reducing the cloud biases would lead to an improvement of the heating rate profiles, which in turn would help in improving other aspects of models' simulations such as the dynamics, cloud feedbacks and surface-atmosphere interactions.

  15. Predictions of Heating Rates in Localized Magnetic Structures From The Photosphere To The Upper Chromosphere

    NASA Astrophysics Data System (ADS)

    Goodman, M. L.

    2003-05-01

    The heating rates due to resistive dissipation of magnetic field aligned currents and of Pedersen currents are computed as functions of height and horizontal radius in a specified 2.5 D magnetic field from the photosphere to the upper chromosphere. The model uses the VAL C height dependent profiles of temperature, and electron, proton, hydrogen, helium, and heavy ion densities together with the magnetic field to compute the anisotropic electrical conductivity tensor for each charged particle species. The magnetic field is parameterized by its maximum magnitude B0, scale height L, characteristic diameter D0, and twist τ which is the ratio of the azimuthal field component to the radial field component. The objective is to determine the ranges of values of these parameters that yield heating rates that are within observational constraints for values of D0 that are above and below the resolution limit of ˜ 150 km. This provides a test of the proposition that Pedersen current dissipation is a major source of chromopsheric heating in magnetic structures throughout the chromosphere, and that it is the rapid increase of charged particle magnetization with height in the lower chromosphere that causes the chromospheric temperature inversion and the rapid increase of the heating rate per unit mass with height in this region. It is found that the heating rate is a monotonically increasing function of B0, L, and τ , and a monotonically decreasing function of D0. For values of D0 below the resolution limit, values of τ >> 1 correspond to strongly heated magnetic structures. This work was supported by NSF grant ATM 9816335.

  16. Heating Rate Effect on the Activation of Viscoelastic Relaxation in Silicate Glasses

    NASA Astrophysics Data System (ADS)

    Naji, Mohamed; Piazza, Francesco; Guimbretière, Guillaume; Canizarès, Aurèlien; Ory, Sandra; Vaills, Yann

    Here we present a direct investigation of the heating rate effect on structural relaxation of sodium silicate glass near the glass transition by means of differential scanning calorimetry, and show the sensitivity of Brillouin light spectroscopy to the dynamic of structural relaxation in the medium range order (∼100 nm).

  17. Estimating High Rates of Transpiration in Woody Vines with the Heat-Balance Method

    USDA-ARS?s Scientific Manuscript database

    Heat-balance sap flow gauges were configured to produce a more thermally uniform stem cross-section under high flow rates. On mature grapevines (Vitis labruscana) either undisturbed in the field or transplanted to large containers (ca. 1m^3 volume), with stem diameters up to 46 mm and leaf area per ...

  18. Estimating High Rates of Transpiration in Woody Vines with the Heat-Balance Method

    USDA-ARS?s Scientific Manuscript database

    Heat-balance sap flow gauges were configured to produce a more thermally uniform stem cross section under high flow rates. On mature grapevines (Vitis labruscana) either undisturbed in the field or transplanted to large containers (ca. 1m3 volume), with stem diameters up to 46 mm and leaf area per v...

  19. Kinetics of silicide formation over a wide range of heating rates spanning six orders of magnitude

    SciTech Connect

    Molina-Ruiz, Manel; Lopeandía, Aitor F.; Gonzalez-Silveira, Marta; Garcia, Gemma; Clavaguera-Mora, Maria T.; Peral, Inma; Rodríguez-Viejo, Javier

    2014-07-07

    Kinetic processes involving intermediate phase formation are often assumed to follow an Arrhenius temperature dependence. This behavior is usually inferred from limited data over narrow temperature intervals, where the exponential dependence is generally fully satisfied. However, direct evidence over wide temperature intervals is experimentally challenging and data are scarce. Here, we report a study of silicide formation between a 12 nm film of palladium and 15 nm of amorphous silicon in a wide range of heating rates, spanning six orders of magnitude, from 0.1 to 10{sup 5 }K/s, or equivalently more than 300 K of variation in reaction temperature. The calorimetric traces exhibit several distinct exothermic events related to interdiffusion, nucleation of Pd{sub 2}Si, crystallization of amorphous silicon, and vertical growth of Pd{sub 2}Si. Interestingly, the thickness of the initial nucleation layer depends on the heating rate revealing enhanced mass diffusion at the fastest heating rates during the initial stages of the reaction. In spite of this, the formation of the silicide strictly follows an Arrhenius temperature dependence over the whole temperature interval explored. A kinetic model is used to fit the calorimetric data over the complete heating rate range. Calorimetry is complemented by structural analysis through transmission electron microscopy and both standard and in-situ synchrotron X-ray diffraction.

  20. Characterizing the effects of scale and heating rate on micro-scale explosive ignition criteria.

    SciTech Connect

    Hafenrichter, Everett Shingo; Pahl, Robert J.

    2005-01-01

    Laser diode ignition experiments were conducted in an effort to characterize the effects of scale and heating rate on micro-scale explosive ignition criteria. Over forty experiments were conducted with various laser power densities and laser spot sizes. In addition, relatively simple analytical and numerical calculations were performed to assist with interpretation of the experimental data and characterization of the explosive ignition criteria.

  1. Analytic heating rate of neutron star merger ejecta derived from Fermi's theory of beta decay

    NASA Astrophysics Data System (ADS)

    Hotokezaka, Kenta; Sari, Re'em; Piran, Tsvi

    2017-06-01

    Macronovae (kilonovae) that arise in binary neutron star mergers are powered by radioactive beta decay of hundreds of r-process nuclides. We derive, using Fermi's theory of beta decay, an analytic estimate of the nuclear heating rate. We show that the heating rate evolves as a power law ranging between t-6/5 and t-4/3. The overall magnitude of the heating rate is determined by the mean values of nuclear quantities, e.g. the nuclear matrix elements of beta decay. These values are specified by using nuclear experimental data. We discuss the role of higher order beta transitions and the robustness of the power law. The robust and simple form of the heating rate suggests that observations of the late-time bolometric light curve ∝ t-4/3 would be direct evidence of a r-process driven macronova. Such observations could also enable us to estimate the total amount of r-process nuclei produced in the merger.

  2. 40 CFR 75.36 - Missing data procedures for heat input rate determinations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... substitute data for CO2 or O2 concentration to calculate heat input rate, as follows. Substitute CO2 data for... determined using a flow monitoring system and a diluent gas (O2 or CO2) monitor, substitute data must be... diluent gas data are unavailable, the owner or operator shall provide substitute O2 or CO2 data for...

  3. Analysis of Görtler Vortices Spanwise Wavelenght Influence in Heat Transfer Rates

    NASA Astrophysics Data System (ADS)

    Souza, Leandro F.; Malatesta, Vinicius; Liu, Joseph T. C.

    2012-11-01

    The centrifugal instability mechanism in boundary layers flows over concave surfaces is responsible for the development of streamwise counter-rotating vortices, known as Görtler vortices. These Vortices create two regions in the spanwise direction, the upwash and downwash regions. The downwash region is responsible to compress the boundary layer towards the wall, increasing drag and heat transfer rates. The upwash region does the opposite. In the nonlinear development of the Görtler vortices the upwash region becomes narrow, and the average drag and heat transfer rate is higher than that for a Blasius boundary layer. In the present research, using a Spatial Direct Numerical Simulation, it is analyzed the influence of the Görtler Vortices spanwise wavelength in heat transfer rates. Different wavelengths are analyzed and compared with experiments. The results show that steady Görtler flow can reach heat transfer rates higher than the turbulent values, even without introducing secondary instabilities. L. Momayez, P. Dupont and H. Peerhossaini, Int J Therm Sci, 43, 753-760 (2004).

  4. Parameteric analysis of a 6500-Btu/kWh heat rate dispersed generator. Final report

    SciTech Connect

    Patel, P.S.

    1985-08-01

    Cost and performance assessments of two alternative system designs for a 2-MW molten carbonate fuel cell power plant yielded encouraging results: a 6500-Btu/kWh heat rate and a total plant investment of $1200-$1300/kW. Differences between the two designs establish a permissible range of operating conditions for the fuel cell that will help guide its development.

  5. Aerodynamic Lifting Force.

    ERIC Educational Resources Information Center

    Weltner, Klaus

    1990-01-01

    Describes some experiments showing both qualitatively and quantitatively that aerodynamic lift is a reaction force. Demonstrates reaction forces caused by the acceleration of an airstream and the deflection of an airstream. Provides pictures of demonstration apparatus and mathematical expressions. (YP)

  6. Aerodynamic Lifting Force.

    ERIC Educational Resources Information Center

    Weltner, Klaus

    1990-01-01

    Describes some experiments showing both qualitatively and quantitatively that aerodynamic lift is a reaction force. Demonstrates reaction forces caused by the acceleration of an airstream and the deflection of an airstream. Provides pictures of demonstration apparatus and mathematical expressions. (YP)

  7. Numerical modeling of the aerodynamics, heat exchange, and combustion of a polydisperse ensemble of coke-ash particles in ascending axisymmetric two-phase flow

    SciTech Connect

    B.B. Rokhman

    2009-07-15

    A two-dimensional stationary model of motion, heat and mass exchange, and chemical reaction of polydisperse coke and ash particles in ascending gas-suspension flow has been constructed with allowance for the turbulent and pseudo turbulent mechanisms of transfer in the dispersed phase. The system of equations that describes motion and heat transfer in the solid phase has been closed at the level of the equations for the second moments of velocity and temperature pulsations, whereas the momentum equations of the carrying medium have been closed using the equation for turbulent gas energy, which allows for the influence of the particles and heterogeneous reactions.

  8. Transonic aerodynamic design experience

    NASA Technical Reports Server (NTRS)

    Bonner, E.

    1989-01-01

    Advancements have occurred in transonic numerical simulation that place aerodynamic performance design into a relatively well developed status. Efficient broad band operating characteristics can be reliably developed at the conceptual design level. Recent aeroelastic and separated flow simulation results indicate that systematic consideration of an increased range of design problems appears promising. This emerging capability addresses static and dynamic structural/aerodynamic coupling and nonlinearities associated with viscous dominated flows.

  9. Random equations in aerodynamics

    NASA Technical Reports Server (NTRS)

    Bharucha-Reid, A. T.

    1984-01-01

    Literature was reviewed to identify aerodynamic models which might be treated by probablistic methods. The numerical solution of some integral equations that arise in aerodynamical problems were investigated. On the basis of the numerical studies a qualitative theory of random integral equations was developed to provide information on the behavior of the solutions of these equations (in particular, boundary and asymptotic behavior, and stability) and their statistical properties without actually obtaining explicit solutions of the equations.

  10. Aerodynamic Shutoff Valve

    NASA Technical Reports Server (NTRS)

    Horstman, Raymond H.

    1992-01-01

    Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

  11. Aerodynamic Shutoff Valve

    NASA Technical Reports Server (NTRS)

    Horstman, Raymond H.

    1992-01-01

    Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

  12. The Effects of Heat Exchange and Thermal Advection on the Rate of Change of Temperature at Ocean Weather Station NOVEMBER.

    DTIC Science & Technology

    The effects of heat exchange across the sea surface and heat advection on the observed rate of change of temperature were examined using a physical...NOVEMBER during 1954 through 1970 were used. A three-dimensional plot of the annual variations of the monthly means of observed rate of change of...temperature produced three distinct trends. Heat exchange primarily contributed to the modification of the observed rate of change of temperature during the

  13. Baroreceptor unloading does not limit forearm sweat rate during severe passive heat stress.

    PubMed

    Schlader, Zachary J; Gagnon, Daniel; Lucas, Rebekah A I; Pearson, James; Crandall, Craig G

    2015-02-15

    This study tested the hypothesis that sweat rate during passive heat stress is limited by baroreceptor unloading associated with heat stress. Two protocols were performed in which healthy subjects underwent passive heat stress that elicited an increase in intestinal temperature of ∼1.8°C. Upon attaining this level of hyperthermia, in protocol 1 (n = 10, 3 females) a bolus (19 ml/kg) of warm (∼38°C) isotonic saline was rapidly (5-10 min) infused intravenously to elevate central venous pressure (CVP), while in protocol 2 (n = 11, 5 females) phenylephrine was infused intravenously (60-120 μg/min) to return mean arterial pressure (MAP) to normothermic levels. In protocol 1, heat stress reduced CVP from 3.9 ± 1.9 mmHg (normothermia) to -0.6 ± 1.4 mmHg (P < 0.001), while saline infusion returned CVP to normothermic levels (5.1 ± 1.7 mmHg; P > 0.999). Sweat rate was elevated by heat stress (1.21 ± 0.44 mg·cm(-2)·min(-1)) but remained unchanged during rapid saline infusion (1.26 ± 0.47 mg·cm(-2)·min(-1), P = 0.5), whereas cutaneous vascular conductance increased from 77 ± 10 to 101 ± 20% of local heating max (P = 0.029). In protocol 2, MAP was reduced with heat stress from 85 ± 7 mmHg to 76 ± 8 mmHg (P = 0.048). Although phenylephrine infusion returned MAP to normothermic levels (88 ± 7 mmHg; P > 0.999), sweat rate remained unchanged during phenylephrine infusion (1.39 ± 0.22 vs. 1.41 ± 0.24 mg·cm(-2)·min(-1); P > 0.999). These data indicate that both cardiopulmonary and arterial baroreceptor unloading do not limit increases in sweat rate during passive heat stress.

  14. Calculation of the gain coefficient in cryogenically cooled Yb : YAG disks at high heat generation rates

    SciTech Connect

    Vadimova, O L; Mukhin, I B; Kuznetsov, I I; Palashov, O V; Perevezentsev, E A; Khazanov, Efim A

    2013-03-31

    We have calculated the stored energy and gain coefficient in disk gain elements cooled to cryogenic temperatures. The problem has been solved with allowance for intense heat generation, amplified spontaneous emission and parasitic lasing, without averaging over any spatial coordinate. The numerical simulation results agree well with experimental data, in particular at high heat generation rates. Experimental data and theoretical analysis indicate that composite disk gain elements containing an undoped region can store considerably more energy due to suppression of amplified spontaneous emission and parasitic lasing. (extreme light fields and their applications)

  15. Baroreceptor unloading does not limit forearm sweat rate during severe passive heat stress

    PubMed Central

    Schlader, Zachary J.; Gagnon, Daniel; Lucas, Rebekah A. I.; Pearson, James

    2014-01-01

    This study tested the hypothesis that sweat rate during passive heat stress is limited by baroreceptor unloading associated with heat stress. Two protocols were performed in which healthy subjects underwent passive heat stress that elicited an increase in intestinal temperature of ∼1.8°C. Upon attaining this level of hyperthermia, in protocol 1 (n = 10, 3 females) a bolus (19 ml/kg) of warm (∼38°C) isotonic saline was rapidly (5–10 min) infused intravenously to elevate central venous pressure (CVP), while in protocol 2 (n = 11, 5 females) phenylephrine was infused intravenously (60–120 μg/min) to return mean arterial pressure (MAP) to normothermic levels. In protocol 1, heat stress reduced CVP from 3.9 ± 1.9 mmHg (normothermia) to −0.6 ± 1.4 mmHg (P < 0.001), while saline infusion returned CVP to normothermic levels (5.1 ± 1.7 mmHg; P > 0.999). Sweat rate was elevated by heat stress (1.21 ± 0.44 mg·cm−2·min−1) but remained unchanged during rapid saline infusion (1.26 ± 0.47 mg·cm−2·min−1, P = 0.5), whereas cutaneous vascular conductance increased from 77 ± 10 to 101 ± 20% of local heating max (P = 0.029). In protocol 2, MAP was reduced with heat stress from 85 ± 7 mmHg to 76 ± 8 mmHg (P = 0.048). Although phenylephrine infusion returned MAP to normothermic levels (88 ± 7 mmHg; P > 0.999), sweat rate remained unchanged during phenylephrine infusion (1.39 ± 0.22 vs. 1.41 ± 0.24 mg·cm−2·min−1; P > 0.999). These data indicate that both cardiopulmonary and arterial baroreceptor unloading do not limit increases in sweat rate during passive heat stress. PMID:25525210

  16. The effect of heat conduction on the rate of chemical reaction in dilute gases

    NASA Astrophysics Data System (ADS)

    Fort, J.; Cukrowski, A. S.

    1997-09-01

    Information statistical theory is used to obtain the second-order terms (similar to those analyzed in the Burnett approximation to the solution of the Boltzmann equation) in the expansion of the nonequilibrium velocity distribution function. These terms are used for the evaluation of the effect of the heat flux on the rate of bimolecular chemical reactions. This effect is shown to be important for reactions characterized by high values of the activation energy. However, very large values of the heat flux would be necessary. The results are compared with those obtained earlier from the square terms calculated from the linearized Boltzmann equation and with recent results due to Nettleton.

  17. Finite-rate water condensation in combustion-heated wind tunnels

    NASA Technical Reports Server (NTRS)

    Erickson, Wayne D.; Mall, Gerald H.; Prabhu, Ramadas K.

    1988-01-01

    A quasi-one-dimensional method for computing finite rate nucleation and droplet growth of water in a supersonic expansion of combustion products is presented. Sample computations are included for the Langley 8 foot High Temperature Tunnel, but the method can also be applied to other combustion heated wind tunnels. The sample results indicate that the free stream static pressure can be in the range of 25 to 60 percent greater than that computed for isentropic nozzle flow without water condensation. The method provides a tool for examining the effects of water condensation on static state properties and velocity of the supersonic stream in combustion heated wind tunnels.

  18. Investigation of Neutral Wind Effects on the Global Joule Heating Rate Using MHD and TI Models

    NASA Astrophysics Data System (ADS)

    Kalafatoglu, E.; Kaymaz, Z.

    2013-12-01

    Precise calculation of global Joule heating rate is a long standing question in thermosphere-ionosphere coupling processes. The absence of the complete and direct, in-situ measurements of the parameters involved in the calculation of Joule heating such as the conductivity of the medium, small-scale variations of electric fields, and neutral winds at the ionospheric heights poses a great uncertainty in its determination. In this work, we study the effects of the neutral wind on the global Joule heating rate. Most of the time, owing to above mentioned difficulties the effects of the neutral wind have been neglected in the calculations. We investigate their effects using BATSRUS MHD model, TIEGCM and GITM. Using horizontal current density, Cowling conductivity, and Pedersen conductivities from the MHD model, we calculate the joule heating rate with and without the neutral wind contribution. We apply the procedure for March 2008 magnetospheric substorm events and quantify the differences to show the neutral wind contribution. We compare the results with those obtained using neutral wind velocities from TIEGCM and GITM models. This way while we compare and demonstrate the discrepancies between the models, we also provide an assessment for the integration of thermospheric and magnetospheric models.

  19. Heat Shock Factor Increases the Reinitiation Rate from Potentiated Chromatin Templates†

    PubMed Central

    Sandaltzopoulos, Raphael; Becker, Peter B.

    1998-01-01

    Transcription by RNA polymerase II is highly regulated at the level of initiation and elongation. Well-documented transcription activation mechanisms, such as the recruitment of TFIID and TFIIB, control the early phases of preinitiation complex formation. The heat shock genes provide an example for transcriptional regulation at a later step: in nuclei TFIID can be detected at the TATA box prior to heat induction. Using cell-free systems for chromatin reconstitution and transcription, we have analyzed the mechanisms by which heat shock factor (HSF) increases transcription of heat shock genes in chromatin. HSF affected transcription of naked DNA templates in multiple ways: (i) by speeding up the rate of preinitiation complex formation, (ii) by increasing the number of productive templates, and (iii) by increasing the reinitiation rate. Under the more physiological conditions of potentiated chromatin templates, HSF affected only the reinitiation rate. Activator-dependent reinitiation of transcription, obviating the slow assembly of the TFIID-TFIIA complex on a promoter, may be especially crucial for genes requiring a fast response to inducers. PMID:9418883

  20. Fundamental Aspects of the Aerodynamics of Turbojet Engine Combustors

    NASA Technical Reports Server (NTRS)

    Barrere, M.

    1978-01-01

    Aerodynamic considerations in the design of high performance combustors for turbojet engines are discussed. Aerodynamic problems concerning the preparation of the fuel-air mixture, the recirculation zone where primary combustion occurs, the secondary combustion zone, and the dilution zone were examined. An aerodynamic analysis of the entire primary chamber ensemble was carried out to determine the pressure drop between entry and exit. The aerodynamics of afterburn chambers are discussed. A model which can be used to investigate the evolution of temperature, pressure, and rate and efficiency of combustion the length of the chamber was developed.

  1. Stagnation-point heat-transfer rate predictions at aeroassist flight conditions

    NASA Technical Reports Server (NTRS)

    Gupta, Roop N.; Jones, Jim J.; Rochelle, William C.

    1992-01-01

    The results are presented for the stagnation-point heat-transfer rates used in the design process of the Aeroassist Flight Experiment (AFE) vehicle over its entire aeropass trajectory. The prediction methods used in this investigation demonstrate the application of computational fluid dynamics (CFD) techniques to a wide range of flight conditions and their usefulness in a design process. The heating rates were computed by a viscous-shock-layer (VSL) code at the lower altitudes and by a Navier-Stokes (N-S) code for the higher altitude cases. For both methods, finite-rate chemically reacting gas was considered, and a temperature-dependent wall-catalysis model was used. The wall temperature for each case was assumed to be radiative equilibrium temperature, based on total heating. The radiative heating was estimated by using a correlation equation. Wall slip was included in the N-S calculation method, and this method implicitly accounts for shock slip. The N-S/VSL combination of projection methods was established by comparison with the published benchmark flow-field code LAURA results at lower altitudes, and the direct simulation Monte Carlo results at higher altitude cases. To obtain the design heating rate over the entire forward face of the vehicle, a boundary-layer method (BLIMP code) that employs reacting chemistry and surface catalysis was used. The ratio of the VSL or N-S method prediction to that obtained from the boundary-layer method code at the stagnation point is used to define an adjustment factor, which accounts for the errors involved in using the boundary-layer method.

  2. Reticulate melanism in western painted turtles (Chrysemys picta bellii): Exploring linkages with habitat and heating rates

    USGS Publications Warehouse

    Gronke, W.K.; Chipps, S.R.; Bandas, S.J.; Higgins, K.F.

    2006-01-01

    In western painted turtles (Chrysemys picta bellii), males often exhibit one of two morphs: (1) a reticulated form, characterized by an intricate network of dark markings on the carapace or (2) a non-reticulated form. Although several hypotheses have been proposed to explain the adaptive significance of reticulate melanism (RM) on western painted turtles, no attempts have been made to document whether RM is linked to habitat conditions or if the presence of melanism affects heating rates. To evaluate these questions, we compared the frequency of adult male turtles with RM across three different habitats: riverine (rivers), lacustrine (lakes) and palustrine (wetland) habitats. Using manipulative experiments, we also tested the hypothesis that body heating rates are higher in turtles with RM. Reticulate melanism occurred on 99 (31%) of 320 male turtles captured in South Dakota from 2002 to 2003. Turtles with reticulate melanism were significantly larger than non-reticulated turtles; RM was not observed on male turtles with carapace lengths 15 cm carapace length) with RM was similar among river (0.54), lake (0.50) and wetland (0.64) habitats, implying that RM is not a habitat-linked trait. Heating rates for turtles with RM were similar to those measured for non-reticulated individuals. Body size, however, influenced heating rates; larger-bodied turtles with lower surface area-to-volume ratio heated more slowly than smaller turtles. Whether RM is a by-product of hormonal regulation or serves an adaptive purpose remains unclear. However, other hypotheses, especially those involving communication (e.g., courtship behavior) and/or gamete protection remain untested for western painted turtles and warrant further investigation.

  3. Finite-Rate Ablation Boundary Conditions for Carbon-Phenolic Heat-Shield

    NASA Technical Reports Server (NTRS)

    Chen, Y.-K.; Milos, Frank S.

    2003-01-01

    A formulation of finite-rate ablation surface boundary conditions, including oxidation, nitridation, and sublimation of carbonaceous material with pyrolysis gas injection, has been developed based on surface species mass conservation. These surface boundary conditions are discretized and integrated with a Navier-Stokes solver. This numerical procedure can predict aerothermal heating, chemical species concentration, and carbonaceous material ablation rate over the heatshield surface of re-entry space vehicles. In this study, the gas-gas and gas-surface interactions are established for air flow over a carbon-phenolic heatshield. Two finite-rate gas-surface interaction models are considered in the present study. The first model is based on the work of Park, and the second model includes the kinetics suggested by Zhluktov and Abe. Nineteen gas phase chemical reactions and four gas-surface interactions are considered in the present model. There is a total of fourteen gas phase chemical species, including five species for air and nine species for ablation products. Three test cases are studied in this paper. The first case is a graphite test model in the arc-jet stream; the second is a light weight Phenolic Impregnated Carbon Ablator at the Stardust re-entry peak heating conditions, and the third is a fully dense carbon-phenolic heatshield at the peak heating point of a proposed Mars Sample Return Earth Entry Vehicle. Predictions based on both finite-rate gas- surface interaction models are compared with those obtained using B' tables, which were created based on the chemical equilibrium assumption. Stagnation point convective heat fluxes predicted using Park's finite-rate model are far below those obtained from chemical equilibrium B' tables and Zhluktov's model. Recession predictions from Zhluktov's model are generally lower than those obtained from Park's model and chemical equilibrium B' tables. The effect of species mass diffusion on predicted ablation rate is also

  4. Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters.

    PubMed

    Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

    2015-01-01

    Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915 measured samples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rate and heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08.

  5. Average Rate of Heat-Related Hospitalizations in 23 States, 2001-2010

    EPA Pesticide Factsheets

    This map shows the 2001??2010 average rate of hospitalizations classified as ??heat-related?? by medical professionals in 23 states that participate in CDC??s hospitalization tracking program. Rates are based on hospital discharge records for May 1 to September 30 of every year. Rates have been age-adjusted to account for differences in the population distribution over time and between states??for example, if one state has a higher proportion of older adults than another. For more information: www.epa.gov/climatechange/science/indicators

  6. Aerodynamic Decelerators for Planetary Exploration: Past, Present, and Future

    NASA Technical Reports Server (NTRS)

    Cruz, Juna R.; Lingard, J. Stephen

    2006-01-01

    In this paper, aerodynamic decelerators are defined as textile devices intended to be deployed at Mach numbers below five. Such aerodynamic decelerators include parachutes and inflatable aerodynamic decelerators (often known as ballutes). Aerodynamic decelerators play a key role in the Entry, Descent, and Landing (EDL) of planetary exploration vehicles. Among the functions performed by aerodynamic decelerators for such vehicles are deceleration (often from supersonic to subsonic speeds), minimization of descent rate, providing specific descent rates (so that scientific measurements can be obtained), providing stability (drogue function - either to prevent aeroshell tumbling or to meet instrumentation requirements), effecting further aerodynamic decelerator system deployment (pilot function), providing differences in ballistic coefficients of components to enable separation events, and providing height and timeline to allow for completion of the EDL sequence. Challenging aspects in the development of aerodynamic decelerators for planetary exploration missions include: deployment in the unusual combination of high Mach numbers and low dynamic pressures, deployment in the wake behind a blunt-body entry vehicle, stringent mass and volume constraints, and the requirement for high drag and stability. Furthermore, these aerodynamic decelerators must be qualified for flight without access to the exotic operating environment where they are expected to operate. This paper is an introduction to the development and application of aerodynamic decelerators for robotic planetary exploration missions (including Earth sample return missions) from the earliest work in the 1960s to new ideas and technologies with possible application to future missions. An extensive list of references is provided for additional study.

  7. Effect of heating rates on the crystallization process of Fe64Co16Zr10B10 amorphous alloy

    NASA Astrophysics Data System (ADS)

    Yu, Wanqiu; Zeng, Haoqun; Sun, Yaming; Sun, Yajuan; Hua, Zhong

    2017-05-01

    Fe64Co16Zr10B10 amorphous alloy prepared by a single roller melt spinning was annealed at 550, 600, 650 and 750 °C for 1 h under different heating rates. The thermal property, microstructure and magnetic property of alloys are investigated by simultaneous thermal analyzer (STA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). At the same heating temperature, the crystallization of amorphous alloy is different along with the change of heating rate. The relationship between the heating rate and the microstructure is studied. The heating rates affect the distribution of elements and result in the difference in the crystallization products. Coercivity (Hc) of Fe64Co16Zr10B10 alloy at the initial crystallization stage can be improved by the decrease of heating rate.

  8. The effect of sampling rate on interpretation of the temporal characteristics of radiative and convective heating in wildland flames

    Treesearch

    David Frankman; Brent W. Webb; Bret W. Butler; Daniel Jimenez; Michael Harrington

    2012-01-01

    Time-resolved radiative and convective heating measurements were collected on a prescribed burn in coniferous fuels at a sampling frequency of 500 Hz. Evaluation of the data in the time and frequency domain indicate that this sampling rate was sufficient to capture the temporal fluctuations of radiative and convective heating. The convective heating signal contained...

  9. The Effect of Wind on the Rate of Heat Loss from Avian Cup-Shaped Nests

    PubMed Central

    Heenan, Caragh B.; Seymour, Roger S.

    2012-01-01

    Forced convection can significantly influence the heat loss from birds and their offspring but effects may be reduced by using sheltered micro-sites such as cavities or constructing nests. The structural and thermal properties of the nests of two species, the spiny-cheeked honeyeater (Acanthagenys rufogularis) and yellow-throated miner (Manorina flavigula), were measured in relation to three wind speeds. Nest dimensions differ between the two species, despite the similar body mass of the incubating adults, however nest conductance is comparable. As wind speed increases, so does the rate of heat loss from the nests of both species, and further still during incubation recesses. The significance of forced convection through the nest is a near-doubling in heat production required by the parent, even when incubating at relatively low wind speeds. This provides confirmation that selecting a sheltered nest site is important for avian reproductive success. PMID:22389689

  10. The effect of wind on the rate of heat loss from avian cup-shaped nests.

    PubMed

    Heenan, Caragh B; Seymour, Roger S

    2012-01-01

    Forced convection can significantly influence the heat loss from birds and their offspring but effects may be reduced by using sheltered micro-sites such as cavities or constructing nests. The structural and thermal properties of the nests of two species, the spiny-cheeked honeyeater (Acanthagenys rufogularis) and yellow-throated miner (Manorina flavigula), were measured in relation to three wind speeds. Nest dimensions differ between the two species, despite the similar body mass of the incubating adults, however nest conductance is comparable. As wind speed increases, so does the rate of heat loss from the nests of both species, and further still during incubation recesses. The significance of forced convection through the nest is a near-doubling in heat production required by the parent, even when incubating at relatively low wind speeds. This provides confirmation that selecting a sheltered nest site is important for avian reproductive success.

  11. Effects of Adiabatic Heating on the High Strain Rate Deformation of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Sorini, Chris; Chattopadhyay, Aditi; Goldberg, Robert K.

    2017-01-01

    Polymer matrix composites (PMCs) are increasingly being used in aerospace structures that are expected to experience complex dynamic loading conditions throughout their lifetime. As such, a detailed understanding of the high strain rate behavior of the constituents, particularly the strain rate, temperature, and pressure dependent polymer matrix, is paramount. In this paper, preliminary efforts in modeling experimentally observed temperature rises due to plastic deformation in PMCs subjected to dynamic loading are presented. To this end, an existing isothermal viscoplastic polymer constitutive formulation is extended to model adiabatic conditions by incorporating temperature dependent elastic properties and modifying the components of the inelastic strain rate tensor to explicitly depend on temperature. It is demonstrated that the modified polymer constitutive model is capable of capturing strain rate and temperature dependent yield as well as thermal softening associated with the conversion of plastic work to heat at high rates of strain. The modified constitutive model is then embedded within a strength of materials based micromechanics framework to investigate the manifestation of matrix thermal softening, due to the conversion of plastic work to heat, on the high strain rate response of a T700Epon 862 (T700E862) unidirectional composite. Adiabatic model predictions for high strain rate composite longitudinal tensile, transverse tensile, and in-plane shear loading are presented. Results show a substantial deviation from isothermal conditions; significant thermal softening is observed for matrix dominated deformation modes (transverse tension and in-plane shear), highlighting the importance of accounting for the conversion of plastic work to heat in the polymer matrix in the high strain rate analysis of PMC structures.

  12. ITER Generic Diagnostic Upper Port Plug Nuclear Heating and Personnel Dose Rate Assesment

    SciTech Connect

    Russell E. Feder and Mahmoud Z. Youssef

    2009-01-28

    Neutronics analysis to find nuclear heating rates and personnel dose rates were conducted in support of the integration of diagnostics in to the ITER Upper Port Plugs. Simplified shielding models of the Visible-Infrared diagnostic and of a large aperture diagnostic were incorporated in to the ITER global CAD model. Results for these systems are representative of typical designs with maximum shielding and a small aperture (Vis-IR) and minimal shielding with a large aperture. The neutronics discrete-ordinates code ATTILA® and SEVERIAN® (the ATTILA parallel processing version) was used. Material properties and the 500 MW D-T volume source were taken from the ITER “Brand Model” MCNP benchmark model. A biased quadrature set equivelant to Sn=32 and a scattering degree of Pn=3 were used along with a 46-neutron and 21-gamma FENDL energy subgrouping. Total nuclear heating (neutron plug gamma heating) in the upper port plugs ranged between 380 and 350 kW for the Vis-IR and Large Aperture cases. The Large Aperture model exhibited lower total heating but much higher peak volumetric heating on the upper port plug structure. Personnel dose rates are calculated in a three step process involving a neutron-only transport calculation, the generation of activation volume sources at pre-defined time steps and finally gamma transport analyses are run for selected time steps. ANSI-ANS 6.1.1 1977 Flux-to-Dose conversion factors were used. Dose rates were evaluated for 1 full year of 500 MW DT operation which is comprised of 3000 1800-second pulses. After one year the machine is shut down for maintenance and personnel are permitted to access the diagnostic interspace after 2-weeks if dose rates are below 100 μSv/hr. Dose rates in the Visible-IR diagnostic model after one day of shutdown were 130 μSv/hr but fell below the limit to 90 μSv/hr 2-weeks later. The Large Aperture style shielding model exhibited higher and more persistent dose rates. After 1-day the dose rate was 230

  13. Scaling of heat production by thermogenic flowers: limits to floral size and maximum rate of respiration.

    PubMed

    Seymour, Roger S

    2010-09-01

    Effect of size of inflorescences, flowers and cones on maximum rate of heat production is analysed allometrically in 23 species of thermogenic plants having diverse structures and ranging between 1.8 and 600 g. Total respiration rate (, micromol s(-1)) varies with spadix mass (M, g) according to in 15 species of Araceae. Thermal conductance (C, mW degrees C(-1)) for spadices scales according to C = 18.5M(0.73). Mass does not significantly affect the difference between floral and air temperature. Aroids with exposed appendices with high surface area have high thermal conductance, consistent with the need to vaporize attractive scents. True flowers have significantly lower heat production and thermal conductance, because closed petals retain heat that benefits resident insects. The florets on aroid spadices, either within a floral chamber or spathe, have intermediate thermal conductance, consistent with mixed roles. Mass-specific rates of respiration are variable between species, but reach 900 nmol s(-1) g(-1) in aroid male florets, exceeding rates of all other plants and even most animals. Maximum mass-specific respiration appears to be limited by oxygen delivery through individual cells. Reducing mass-specific respiration may be one selective influence on the evolution of large size of thermogenic flowers.

  14. Effect of Latent Heat of Freezing on Crustal Generation at Ultraslow Spreading Rates

    NASA Astrophysics Data System (ADS)

    Sleep, N. H.; Warren, J. M.

    2013-12-01

    The transition between slow and ultraslow ridge axes occurs at the spreading rate below which steady state molten rock cannot exist above the normal Moho depth of ca. 6 km. The latent heat of basaltic magma freezing within the mantle and the kinematics of the seafloor spreading play significant roles in this transition. Using thermal models, we show that freezing of melt at mantle depths buffers temperature due to latent heat of freezing. This allows steady state crustal magma at lower spreading rates than when all the melt freezes at shallow crustal depths. Two quasi-stable seafloor-spreading patterns are possible: (1) basaltic magma along a narrow axial zone, maintaining a hot, weak axial lid that favors this extension pattern; (2) extension in simple shear over a broad zone with isotherms that are horizontal within the cool lid, favoring extension in simple shear. The statistics of basalt, gabbro, melt-impregnated peridotite, and peridotite dredged from transitional ridge axes indicates that the mode of crustal generation is extremely variable at ultraslow spreading rates. Portions of the easternmost Southwest Indian Ridge (SWIR) are spreading at 14 mm per year and consist of 90 percent peridotite, whereas the SWIR Oblique Segment has the same spreading rate but only 37 percent peridotite. Overall, the dredge statistics indicate that some, but not all, the latent heat of ascending magmas is released at mantle depth, that both quasi-stable seafloor-spreading geometries occur, and that magma ascent focuses locally along the strike of transitional ridge axes.

  15. Torrefaction of invasive alien plants: Influence of heating rate and other conversion parameters on mass yield and higher heating value.

    PubMed

    Mundike, Jhonnah; Collard, François-Xavier; Görgens, Johann F

    2016-06-01

    With the aim of controlling their proliferation, two invasive alien plants, Lantana camara (LC) and Mimosa pigra (MP), both widespread in Africa, were considered for torrefaction for renewable energy applications. Using thermogravimetric analysis, the influence of heating rate (HR: 2.18-19.82°Cmin(-1)) together with variable temperature and hold time on char yield and HHV (in a bomb calorimeter) were determined. Statistically significant effects of HR on HHV with optima at 10.5°Cmin(-1) for LC and 20°Cmin(-1) for MP were obtained. Increases of HHV up to 0.8MJkg(-1) or energy yield greater than 10%, together with a 3-fold reduction in torrefaction conversion time could be achieved by optimisation of HR. Analysis of the torrefaction volatiles by TG-MS showed that not only hemicelluloses, but also lignin conversion, could influence the optimum HR value.

  16. Genetic component of sensitivity to heat stress for nonreturn rate of Brazilian Holstein cattle.

    PubMed

    Santana, M L; Bignardi, A B; Stefani, G; El Faro, L

    2017-08-01

    The objectives of the present study were: 1) to investigate variation in the genetic component of heat stress for nonreturn rate at 56 days after first artificial insemination (NR56); 2) to identify and characterize the genotype by environment interaction (G × E) due to heat stress for NR56 of Brazilian Holstein cattle. A linear random regression model (reaction norm model) was applied to 51,748 NR56 records of 28,595 heifers and multiparous cows. The decline in NR56 due to heat stress was more pronounced in milking cows compared to heifers. The age of females at first artificial insemination and temperature-humidity index (THI) exerted an important influence on the genetic parameters of NR56. Several evidence of G × E on NR56 were found as the high slope/intercept ratio and frequent intersection of reaction norms. Additionally, the genetic correlation between NR56 at opposite extremes of the THI scale reached estimates below zero, indicating that few of the same genes are responsible for NR56 under conditions of thermoneutrality and heat stress. The genetic evaluation and selection for NR56 in Holstein cattle reared under (sub)tropical conditions should therefore take into consideration the genetic variation on age at insemination and G × E due to heat stress. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Experimental study on latent heat storage characteristics of W/O emulsion -Supercooling rate of dispersed water drops by direct contact heat exchange-

    NASA Astrophysics Data System (ADS)

    Morita, Shin-ichi; Hayamizu, Yasutaka; Horibe, Akihiko; Haruki, Naoto; Inaba, Hideo

    2013-04-01

    Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand-concentration on day-time of summer by the air conditioning. The flowable latent heat storage material, Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enable to transport the latent heat in a pipe. The flowable latent heat storage material can realize the pipe size reduction and system efficiency improvement. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase brings the obstruction of latent heat storage. The latent heat storage rates of dispersed water drops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The water drops in emulsion has the diameter within 3 ˜ 25μm, the averaged water drop diameter is 7.3μm and the standard deviation is 2.9μm. The direct contact heat exchange method is chosen as the phase change rate evaluation of water drops in W/O emulsion. The supercooled temperature and the cooling rate are set as parameters of this study. The evaluation is performed by comparison between the results of this study and the past research. The obtained experimental result is shown that the 35K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It was clarified that the supercooling rate of dispersed water particles in emulsion shows the larger value than that of the bulk water.

  18. Effects of slip, slip rate, and shear heating on the friction of granite

    USGS Publications Warehouse

    Blanpied, M.L.; Tullis, T.E.; Weeks, J.D.

    1998-01-01

    The stability of fault slip is sensitive to the way in which frictional strength responds to changes in slip rate and in particular to the effective velocity dependence of steady state friction ????ss/?? ln V. This quantity can vary substantially with displacement, temperature and slip rate. To investigate the physical basis for this behavior and the possible influence of shear heating, we slid initially bare granite surfaces in unconfined rotary shear to displacements of hundreds of millimeters at normal stresses, ??n, of 10 and 25 MPa and at room temperature. We imposed step changes in slip rate within the range 10-2 to 103.5 ??m/s and also monitored frictional heating with thermistors embedded in the granite. The transient response of ?? to slip rate steps was fit to a rate- and state-dependent friction law using two state variables to estimate the values of several parameters in the constitutive law. The first 20 mm of slip shows rising friction and falling ????ss/?? ln V; further slip shows roughly constant friction, ????ss/?? ln V and parameter values, suggesting that a steady state condition is reached on the fault surface. At V ??? 10 ??m/s, ????ss/?? ln V = -0.004 ?? 0.001. At higher rates the response is sensitive to normal stress: At ??n = 25 MPa granite shows a transition to effective velocity strengthening (????ss/?? ln V = 0.008 ?? 0.004) at the highest slip rates tested. At 10 MPa granite shows a less dramatic change to ????ss/?? ln V ??? 0 at the highest rates. The maximum temperature measured in the granite is ???60??C at 25 MPa and 103.5 ??m/s. Temperatures are in general agreement with a numerical model of heat conduction which assumes spatially homogeneous frictional heating over the sliding surface. The simplest interpretation of our measurements of ????ss/?? ln V is that the granite is inherently veocity weakening (?????ss/??? In V 0 mimics velocity strengthening. These results have implications for the frictional behavior of faults during

  19. Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters

    PubMed Central

    Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

    2015-01-01

    Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915measuredsamples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rateand heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08. PMID:26624613

  20. A Wind-Tunnel Investigation to Determine the Effect of Various Head Designs on the Aerodynamic Characteristics in Pitch of the Army Ordnance Corps T205 3.5-Inch Heat Rocket

    NASA Technical Reports Server (NTRS)

    Morrison, William D., Jr.; Kuhn, Richard E.

    1952-01-01

    The aerodynamic characteristics in pitch of the Army Ordnance Corps T205 3.5-inch HEAT rocket with various head designs and one fin modification have been determined at velocities of 500, 700 and 900 feet per second in the Langley high-speed 7- by 10-foot tunnel. The results presented are those of the full-scale model. Comparison of results obtained at 500 feet per second shows, in general, that for changes on the forward portion of the head the missile configurations having the greatest stability - most rearward center-of-loads location - were those having the highest drag. However, very limited comparisons indicate that the shape of the rear position of the head may be an important factor in reducing the drag and increasing the restoring moments. Generally, large increases in drag were noted for the various head designs with an increase in Mach number from 0.62 to 0.82. Pitching-moment-curve slopes increased with Mach number on all models except those having reasonably well-faired forward sections. These models showed a decrease in stability with increases in Mach number.

  1. Autonomic responses to heat pain: Heart rate, skin conductance, and their relation to verbal ratings and stimulus intensity.

    PubMed

    Loggia, Marco L; Juneau, Mylène; Bushnell, M Catherine

    2011-03-01

    In human pain experiments, as well as in clinical settings, subjects are often asked to assess pain using scales (eg, numeric rating scales). Although most subjects have little difficulty in using these tools, some lack the necessary basic cognitive or motor skills (eg, paralyzed patients). Thus, the identification of appropriate nonverbal measures of pain has significant clinical relevance. In this study, we assessed heart rate (HR), skin conductance (SC), and verbal ratings in 39 healthy male subjects during the application of twelve 6-s heat stimuli of different intensities on the subjects' left forearm. Both HR and SC increased with more intense painful stimulation. However, HR but not SC, significantly correlated with pain ratings at the group level, suggesting that HR may be a better predictor of between-subject differences in pain than is SC. Conversely, changes in SC better predicted variations in ratings within a given individual, suggesting that it is more sensitive to relative changes in perception. The differences in findings derived from between- and within-subject analyses may result from greater within-subject variability in HR. We conclude that at least for male subjects, HR provides a better predictor of pain perception than SC, but that data should be averaged over several stimulus presentations to achieve consistent results. Nevertheless, variability among studies, and the indication that gender of both the subject and experimenter could influence autonomic results, lead us to advise caution in using autonomic or any other surrogate measures to infer pain in individuals who cannot adequately report their perception. Skin conductance is more sensitive to detect within-subject perceptual changes, but heart rate appears to better predict pain ratings at the group level.

  2. Tropical precipitation rates during SOP-1, FGGE, estimated from heat and moisture budgets

    NASA Technical Reports Server (NTRS)

    Pedigo, Catherine B.; Vincent, Dayton G.

    1990-01-01

    Using the NASA Goddard Laboratory analyses collected during the first FGGE Special Observing Period, global estimates of precipitation rates were derived for the domain between 30-deg N to 30-deg S, and the results were compared to OLR patterns and to each other to evaluate their consistency and reliability. Regional averages are presented to examine the variability of rainfall rates among selected regions of the Southern Hemisphere tropics. Finally, precipitable water was computed and compared to results derived from SMMR estimates and to the precipitation patterns. Results show that the heat and moisture budget estimates of precipitation compare favorably. Vertical profiles reveal that maximum convective heating occurs in the middle troposphere. The profile of the South Pacific convergence zone region compares best with profiles obtained over the western North Pacific.

  3. Oxidation and decomposition mechanisms of air sensitive aluminum clusters at high heating rates

    NASA Astrophysics Data System (ADS)

    DeLisio, Jeffery B.; Mayo, Dennis H.; Guerieri, Philip M.; DeCarlo, Samantha; Ives, Ross; Bowen, Kit; Eichhorn, Bryan W.; Zachariah, Michael R.

    2016-09-01

    Molecular near zero oxidation state clusters of metals are of interest as fuel additives. In this work high heating rate decomposition of the Al(I) tetrameric cluster, [AlBr(NEt3)]4 (Et = C2H5), was studied at heating rates of up to 5 × 105 K/s using temperature-jump time-of-flight mass spectrometry (T-jump TOFMS). Gas phase Al and AlHx species were rapidly released during decomposition of the cluster, at ∼220 °C. The activation energy for decomposition was determined to be ∼43 kJ/mol. Addition of an oxidizer, KIO4, increased Al, AlO, and HBr signal intensities, showing direct oxidation of the cluster with gas phase oxygen.

  4. Tropical precipitation rates during SOP-1, FGGE, estimated from heat and moisture budgets

    NASA Technical Reports Server (NTRS)

    Pedigo, Catherine B.; Vincent, Dayton G.

    1990-01-01

    Using the NASA Goddard Laboratory analyses collected during the first FGGE Special Observing Period, global estimates of precipitation rates were derived for the domain between 30-deg N to 30-deg S, and the results were compared to OLR patterns and to each other to evaluate their consistency and reliability. Regional averages are presented to examine the variability of rainfall rates among selected regions of the Southern Hemisphere tropics. Finally, precipitable water was computed and compared to results derived from SMMR estimates and to the precipitation patterns. Results show that the heat and moisture budget estimates of precipitation compare favorably. Vertical profiles reveal that maximum convective heating occurs in the middle troposphere. The profile of the South Pacific convergence zone region compares best with profiles obtained over the western North Pacific.

  5. Space Shuttle Solid Rocket Motor Plume Pressure and Heat Rate Measurements

    NASA Technical Reports Server (NTRS)

    vonEckroth, Wulf; Struchen, Leah; Trovillion, Tom; Perez, Ravael; Nereolich, Shaun; Parlier, Chris

    2012-01-01

    The Solid Rocket Booster (SRB) Main Flame Deflector (MFD) at Launch Complex 39A was instrumented with sensors to measure heat rates, pressures, and temperatures on the last three Space Shuttle launches. Because the SRB plume is hot and erosive, a robust Tungsten Piston Calorimeter was developed to compliment the measurements made by off-the-shelf sensors. Witness materials were installed and their melting and erosion response to the Mach 2 / 4500 F / 4-second duration plume was observed. The data show that the specification document used for the design of the MFD thermal protection system over-predicted heat rates by a factor of 3 and under-predicted pressures by a factor of 2. These findings will be used to baseline NASA Computational Fluid Dynamics models and develop innovative MFD designs for the Space Launch System (SLS) before this vehicle becomes operational in 2017.

  6. Study of the Emitted Dose After Two Separate Inhalations at Different Inhalation Flow Rates and Volumes and an Assessment of Aerodynamic Characteristics of Indacaterol Onbrez Breezhaler(®) 150 and 300 μg.

    PubMed

    Abadelah, Mohamad; Chrystyn, Henry; Bagherisadeghi, Golshan; Abdalla, Gaballa; Larhrib, Hassan

    2017-07-10

    Onbrez Breezhaler® is a low-resistance capsule-based device that was developed to deliver indacaterol maleate. The study was designed to investigate the effects of both maximum flow rate (MIF) and inhalation volume (Vin) on the dose emission of indacaterol 150 and 300 μg dose strengths after one and two inhalations using dose unit sampling apparatus (DUSA) as well as to study the aerodynamic characteristics of indacaterol Breezhaler® using the Andersen cascade impactor (ACI) at a different set of MIF and Vin. Indacaterol 150 and 300 μg contain equal amounts of lactose per carrier. However, 150 μg has the smallest carrier size. The particle size distribution (PSD) of indacaterol DPI formulations 150 and 300 μg showed that the density of fine particles increased with the increase of the primary pressure. For both strengths (150 μg and 300 μg), ED1 increased and ED2 decreased when the inhalation flow rate and inhaled volume increased. The reduction in ED1 and subsequent increase in ED2 was such that when the Vin is greater than 1 L, then 60 L/min could be regarded as the minimum MIF. The Breezhaler was effective in producing respirable particles with an MMAD ≤5 μm irrespective of the inhalation flow rate, but the mass fraction of particles with an aerodynamic diameter <3 μm is more pronounced between 60 and 90 L/min. The dose emission of indacaterol was comparable for both dose strengths 150 and 300 μg. These in vitro results suggest that a minimum MIF of 60 L/min is required during routine use of Onbrez Breezhaler®, and confirm the good practice to make two separate inhalations from the same dose.

  7. Exploratory Development on Oxidation Behavior of Titanium Alloys under High Heating Rates

    DTIC Science & Technology

    1975-04-01

    0.269 Metalljic Aluminum 0.080 Boron 0.010 Chromi um 0.006 Copper 0.0015 Iron 0.200 Lead 0.002t Magnesium 0.005 Manganese 0.005 Molybdenum 0.004 Nickel...equal to the geometric projected specimen area. 324 At high heating rates, we propose that this effective area is increased by a mechanism associated

  8. Calculation of laminar heating rates on three-dimensional configurations using the axisymmetric analogue

    NASA Technical Reports Server (NTRS)

    Hamilton, H. H., II

    1980-01-01

    A theoretical method was developed for computing approximate laminar heating rates on three dimensional configurations at angle of attack. The method is based on the axisymmetric analogue which is used to reduce the three dimensional boundary layer equations along surface streamlines to an equivalent axisymmetric form by using the metric coefficient which describes streamline divergence (or convergence). The method was coupled with a three dimensional inviscid flow field program for computing surface streamline paths, metric coefficients, and boundary layer edge conditions.

  9. Compendium of NASA Langley reports on hypersonic aerodynamics

    NASA Technical Reports Server (NTRS)

    Sabo, Frances E.; Cary, Aubrey M.; Lawson, Shirley W.

    1987-01-01

    Reference is made to papers published by the Langley Research Center in various areas of hypersonic aerodynamics for the period 1950 to 1986. The research work was performed either in-house by the Center staff or by other personnel supported entirely or in part by grants or contracts. Abstracts have been included with the references when available. The references are listed chronologically and are grouped under the following general headings: (1) Aerodynamic Measurements - Single Shapes; (2) Aerodynamic Measurements - Configurations; (3) Aero-Heating; (4) Configuration Studies; (5) Propulsion Integration Experiment; (6) Propulsion Integration - Study; (7) Analysis Methods; (8) Test Techniques; and (9) Airframe Active Cooling Systems.

  10. Influence of drying temperature, water content, and heating rate on gelatinization of corn starches.

    PubMed

    Altay, Filiz; Gunasekaran, Sundaram

    2006-06-14

    The gelatinization properties of starch extracted from corn and waxy corn dried at different temperatures were determined at various water contents and heating rates by differential scanning calorimetry. All gelatinization transition temperatures increased with drying temperature and heating rate. Onset and peak temperatures remained relatively constant, whereas end temperature decreased in the presence of excess water. The gelatinization enthalpy (deltaH(g)) of corn starch decreased with drying temperature at 50% water; however, it remained constant for waxy corn starch. The effects of water content and heating rate on deltaH(g) were dependent on each other. The minimum water levels required for gelatinization of starch extracted from corn dried at 20 and 100 degrees C are 21 and 29%, respectively. The activation energy (E(a)) was calculated using an Arrhenius-type equation and two first-order models; the degree of conversion (alpha) was predicted using a newly proposed model that produced good results for both E(a) and alpha.

  11. Species production and heat release rates in two-layered natural gas fires

    SciTech Connect

    Zukoski, E.E.; Morehart, J.H.; Kubota, T.; Toner, S.J. )

    1991-02-01

    A fire burning in an enclosure with restricted ventilation will result in the accumulation of a layer of warm products of combustion mixed with entrained air adjacent to the ceiling. For many conditions, the depth of this layer will extend to occupy a significant fraction of the volume of the room. Eventually, the interface between this vitiated ceiling layer and the uncontaminated environment below will position itself so that a large portion of the combustion processes occur in this vitiated layer. A description is given of experimental work concerning the rates of formation of product species and heat release in a turbulent, buoyant natural gas diffusion flame burning in this two-layered configuration. The enclosure was modeled by placing a hood above a burner so that it accumulated the plume gases, and the unsteady development of the ceiling layer was modeled by the direct addition of air into the upper portion of the hood. Measurements of the composition of these gases allowed the computation of stoichiometries and heat release rates. These investigations showed that the species produced in the flame depend primarily on the stoichiometry of the gases present in the ceiling layer and weakly on the temperature of the layer, but are independent of the fuel pair ratio of the mass transported into the layer by the plume. Heat release rates in the fires were compared to a theoretical limit based on a stoichiometric reaction of fuel and air with excess components left unchanged by the combustion.

  12. The influence of the magnetic field on the heat transfer rate in rotating spherical shells

    NASA Astrophysics Data System (ADS)

    Cabello, Ares; Avila, Ruben

    2016-11-01

    Studies of the relationship between natural convection and magnetic field generation in spherical annular geometries with rotation are essential to understand the internal dynamics of the terrestrial planets. In such studies it is important to calculate and analyze the heat transfer rate at the inner and the outer spheres that confine the spherical gap. Previous investigations indicate that the magnetic field has a stabilizing effect on the onset of the natural convection, reduces the intensity of convection and modifies the flow patterns. However so far it is still unclear how the magnetic field change the heat transfer rate behaviour. We investigate the heat transfer rate (Nu) in a rotating spherical gap with a self gravity field varying linearly with radius, and its relation with the intensity of the magnetic field induced by the geodynamo effect. The Boussinesq fluid equations are solved by using a spectral element method (SEM). To avoid the singularity at the poles, the cubed-sphere algorithm is used to generate the spherical mesh. Several cases are simulated in which the Rayleigh number, the magnetic Reynolds number and the Taylor number are the variable parameters. The flow patterns, the temperature distribution and the Nusselt numbers at both spheres are calculated. Special thanks to DGAPA-UNAM Project PAPIIT IN11731, sponsor of this investigation.

  13. Melting processes of oligomeric α and β isotactic polypropylene crystals at ultrafast heating rates.

    PubMed

    Ji, Xiaojing; He, Xuehao; Jiang, Shichun

    2014-02-07

    The melting behaviors of α (stable) and β (metastable) isotactic polypropylene (iPP) crystals at ultrafast heating rates are simulated with atomistic molecular dynamics method. Quantitative information about the melting processes of α- and β-iPP crystals at atomistic level is achieved. The result shows that the melting process starts from the interfaces of lamellar crystal through random dislocation of iPP chains along the perpendicular direction of lamellar crystal structure. In the melting process, the lamellar crystal gradually expands but the corresponding thickness decreases. The analysis shows that the system expansion lags behind the crystallinity decreasing and the lagging extents for α- and β-iPP are significantly different. The apparent melting points of α- and β-iPP crystals rise with the increase of the heating rate and lamellar crystal thickness. The apparent melting point of α-iPP crystal is always higher than that of β-iPP at differently heating rates. Applying the Gibbs-Thomson rule and the scaling property of the melting kinetics, the equilibrium melting points of perfect α- and β-iPP crystals are finally predicted and it shows a good agreement with experimental result.

  14. Melting processes of oligomeric α and β isotactic polypropylene crystals at ultrafast heating rates

    SciTech Connect

    Ji, Xiaojing; He, Xuehao E-mail: scjiang@tju.edu.cn; Jiang, Shichun E-mail: scjiang@tju.edu.cn

    2014-02-07

    The melting behaviors of α (stable) and β (metastable) isotactic polypropylene (iPP) crystals at ultrafast heating rates are simulated with atomistic molecular dynamics method. Quantitative information about the melting processes of α- and β-iPP crystals at atomistic level is achieved. The result shows that the melting process starts from the interfaces of lamellar crystal through random dislocation of iPP chains along the perpendicular direction of lamellar crystal structure. In the melting process, the lamellar crystal gradually expands but the corresponding thickness decreases. The analysis shows that the system expansion lags behind the crystallinity decreasing and the lagging extents for α- and β-iPP are significantly different. The apparent melting points of α- and β-iPP crystals rise with the increase of the heating rate and lamellar crystal thickness. The apparent melting point of α-iPP crystal is always higher than that of β-iPP at differently heating rates. Applying the Gibbs-Thomson rule and the scaling property of the melting kinetics, the equilibrium melting points of perfect α- and β-iPP crystals are finally predicted and it shows a good agreement with experimental result.

  15. Charts Adapted from Van Driest's Turbulent Flat-plate Theory for Determining Values of Turbulent Aerodynamic Friction and Heat-transfer Coefficients

    NASA Technical Reports Server (NTRS)

    Lee, Dorothy B; Faget, Maxime A

    1956-01-01

    A modified method of Van Driest's flat-plate theory for turbulent boundary layer has been found to simplify the calculation of local skin-friction coefficients which, in turn, have made it possible to obtain through Reynolds analogy theoretical turbulent heat-transfer coefficients in the form of Stanton number. A general formula is given and charts are presented from which the modified method can be solved for Mach numbers 1.0 to 12.0, temperature ratios 0.2 to 6.0, and Reynolds numbers 0.2 times 10 to the 6th power to 200 times 10 to the 6th power.

  16. Constraints on Lunar Heat Flow Rates from Diviner Lunar Radiometer Polar Observations

    NASA Astrophysics Data System (ADS)

    Paige, D. A.; Siegler, M. A.; Vasavada, A. R.

    2010-12-01

    The heat flow rate from the lunar interior is a fundamental property of the moon that is related to its composition, interior structure and history. Lunar heat flow rates have been measured at the Apollo 15 and 17 landing sites [1], but it is widely believed that the measured values of 0.021 Wm-2 and 0.016 Wm-2 respectively may not be representative of the moon as a whole due to the presence of enhanced radiogenic elements at these landing sites [2]. The Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter [3] has acquired an extensive set of thermal emission from the lunar surface at infrared wavelengths, including the first radiometric measurements of surface temperatures at the lunar poles [4]. Due to its low obliquity and rough topography, the moon has extensive cryogenic regions at high latitudes that never receive direct sunlight. The temperatures of the coldest of these regions can be used to place upper limits on the heat flow rate from the lunar interior because if other heat sources are neglected, then surface thermal emission is balanced by heat flow from warmer lunar interior [5]. Diviner has mapped the north and south polar regions over a complete annual cycle and we have identified a 4 km2 area within Hermite Crater in the north polar region that has a winter season nighttime Channel 9 (100-400 micron) brightness temperatures in of less than 20K. These low temperatures would imply a lunar heat flow rate of less than 0.010 Wm-2, which may be consistent with expectations for regions of the moon that do not contain enhanced concentrations of radiogenic elements [2,6], as is the case for the north polar region of the moon [7]. [1] Langseth, M. G. et al, Proc. Lunar Sci. Conf, 7th, 3143-3171, 1976. [2] Warren, P. H. and K. K. L. Rasmussen, JGR 92, 3453-3465, 1987. [3] Paige, D. A. et al, Space Sci. Rev, 150:125-160, 2010. [4] Paige, D. A. et al., Science, in press, 2010. [5] Watson, K. JGR 72, 3301-3302, 1967. [6] Wieczorek, M. A. and R

  17. Cool Bands: Wing bands decrease rate of heating, but not equilibrium temperature in Anartia fatima.

    PubMed

    Brashears, Jake; Aiello, Annette; Seymoure, Brett M

    2016-02-01

    Butterflies regulate their internal thoracic temperature in order to optimize performance activities (e.g. flight, foraging). Previous research has shown that butterfly wings, particularly the innermost portions, play a role in thermoregulation. We investigated to see whether a lightly colored wing band would alter the thermal properties of the banded peacock butterfly (Anartia fatima) with two within subject experiments in a laboratory setting: (1) band color manipulation in which euthanized individuals were heated to thermal equilibrium with the band unaltered and then again with the wing darkened; (2) wing ablation in which individuals already run through experiment 1 were heated to equilibrium two more times; once with the outer portion of the wing including the band removed and then with the entire wing removed. Individuals were spread so that the dorsal surface of the wing was exposed to illumination from a lamp suspended above. Twelve Anartia fatima males were collected in Panama and were run through experiment one. Four individuals were run through experiment two. We found no effect of darkening the band on the internal thoracic equilibrium temperature, but the darkened band did increase the rate of heating. The wing ablation experiment revealed that wing removal lowered the internal thoracic equilibrium temperature but did not affect the heating rate. Therefore we show that butterfly bands may be important in butterfly thermoregulation and we discuss the importance of the wing band on thermoregulatory abilities in Anartia fatima with respect to the butterfly's natural history. We conclude that the wing band may allow butterflies to reduce heat stress induced by their warm environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Powered-Lift Aerodynamics and Acoustics. [conferences

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Powered lift technology is reviewed. Topics covered include: (1) high lift aerodynamics; (2) high speed and cruise aerodynamics; (3) acoustics; (4) propulsion aerodynamics and acoustics; (5) aerodynamic and acoustic loads; and (6) full-scale and flight research.

  19. The effect of heating rate on the cutaneous vasomotion responses of forearm and leg skin in humans.

    PubMed

    Del Pozzi, Andrew T; Miller, James T; Hodges, Gary J

    2016-05-01

    We examined skin blood flow (SkBF) and vasomotion in the forearm and leg using laser-Doppler fluxmetry (LDF) and spectral analysis to investigate endothelial, sympathetic, and myogenic activities in response to slow (0.1 °C·10 s(-1)) and fast (0.5 °C·10 s(-1)) local heating. At 33 °C (thermoneutral) endothelial activity was higher in the legs than the forearms (P ≤ 0.02). Fast-heating increased SkBF more than slow heating (P=0.037 forearm; P=0.002 leg). At onset of 42 °C, endothelial (P=0.043 forearm; P=0.48 leg) activity increased in both regions during the fast-heating protocol. Following prolonged heating (42 °C) endothelial activity was higher in both the forearm (P=0.002) and leg (P<0.001) following fast-heating. These results confirm regional differences in the response to local heating and suggest that the greater increase in SkBF in response to fast local heating is initially due to increased endothelial and sympathetic activity. Furthermore, with sustained local skin heating, greater vasodilatation was observed with fast heating compared to slow heating. These data indicate that this difference is due to greater endothelial activity following fast heating compared to slow heating, suggesting that the rate of skin heating may alter the mechanisms contributing to cutaneous vasodilatation.

  20. Phase change paint tests to investigate effects of TPS tiles on heating rates of the Rockwell space shuttle orbiter (test OH4C, model 21-0)

    NASA Technical Reports Server (NTRS)

    Quan, M.

    1975-01-01

    Information and data from wind tunnel tests conducted on 0.0175-scale models of the space shuttle orbiter are presented. The primary objective of the tests was to evaluate aerodynamic heating effects of the tiles in the thermal protection system (TPS). Tile gap depth and flow orientation effects on the TPS were investigated. Tile patterns were cut into the undersides of the orbiter models to simulate the gaps. One model was left smooth for comparison.

  1. Planar laser-induced fluorescence imaging of flame heat release rate

    SciTech Connect

    Paul, P.H.; Najm, H.N.

    1997-12-12

    Local heat release rate represents one of the most interesting experimental observables in the study of unsteady reacting flows. The direct measure of burning or heat release rate as a field variable is not possible. Numerous experimental investigations have relied on inferring this type of information as well as flame front topology from indirect measures which are presumed to be correlated. A recent study has brought into question many of the commonly used flame front marker and burning rate diagnostics. This same study found that the concentration of formyl radical offers the best possibility for measuring flame burning rate. However, primarily due to low concentrations, the fluorescence signal level from formyl is too weak to employ this diagnostic for single-pulse measurements of turbulent reacting flows. In this paper the authors describe and demonstrate a new fluorescence-based reaction front imaging diagnostic suitable for single-shot applications. The measurement is based on taking the pixel-by-pixel product of OH and CH{sub 2}O planar laser-induced fluorescence images to yield an image closely related to a reaction rate. The spectroscopic and collisional processes affecting the measured signals are discussed and the foundation of the diagnostic, as based on laminar and unsteady flame calculations, is presented. The authors report the results of applying this diagnostic to the study of a laminar premixed flame subject to an interaction with an isolated line-vortex pair.

  2. Applied computational aerodynamics

    SciTech Connect

    Henne, P.A.

    1990-01-01

    The present volume discusses the original development of the panel method, the mapping solutions and singularity distributions of linear potential schemes, the capabilities of full-potential, Euler, and Navier-Stokes schemes, the use of the grid-generation methodology in applied aerodynamics, subsonic airfoil design, inverse airfoil design for transonic applications, the divergent trailing-edge airfoil innovation in CFD, Euler and potential computational results for selected aerodynamic configurations, and the application of CFD to wing high-lift systems. Also discussed are high-lift wing modifications for an advanced-capability EA-6B aircraft, Navier-Stokes methods for internal and integrated propulsion system flow predictions, the use of zonal techniques for analysis of rotor-stator interaction, CFD applications to complex configurations, CFD applications in component aerodynamic design of the V-22, Navier-Stokes computations of a complete F-16, CFD at supersonic/hypersonic speeds, and future CFD developments.

  3. The effects of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of a large-scale rotating turbine model. Volume 3: Heat transfer data tabulation 65 percent axial spacing

    NASA Technical Reports Server (NTRS)

    Dring, R. P.; Blair, M. F.; Joslyn, H. D.

    1986-01-01

    This is Volume 3 - Heat Transfer Data Tabulation (65 percent Axial Spacing) of a combined experimental and analytical program which was conducted to examine the effects of inlet turbulence on airfoil heat transfer. The experimental portion of the study was conducted in a large-scale (approximately 5X engine), ambient temperature, rotating turbine model configured in both single stage and stage-and-a-half arrangements. Heat transfer measurements were obtained using low-conductivity airfoils with miniature thermocouples welded to a thin, electrically heated surface skin. Heat transfer data were acquired for various combinations of low or high inlet turbulence intensity, flow coefficient, first-stator/rotor axial spacing, Reynolds number and relative circumferential position of the first and second stators.

  4. An Efficient Approximation of the Coronal Heating Rate for use in Global Sun-Heliosphere Simulations

    NASA Astrophysics Data System (ADS)

    Cranmer, Steven R.

    2010-02-01

    The origins of the hot solar corona and the supersonically expanding solar wind are still the subject of debate. A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a physically motivated way of specifying the coronal heating rate. Recent one-dimensional models have been found to reproduce many observed features of the solar wind by assuming the energy comes from Alfvén waves that are partially reflected, then dissipated by magnetohydrodynamic turbulence. However, the nonlocal physics of wave reflection has made it difficult to apply these processes to more sophisticated (three-dimensional) models. This paper presents a set of robust approximations to the solutions of the linear Alfvén wave reflection equations. A key ingredient of the turbulent heating rate is the ratio of inward-to-outward wave power, and the approximations developed here allow this to be written explicitly in terms of local plasma properties at any given location. The coronal heating also depends on the frequency spectrum of Alfvén waves in the open-field corona, which has not yet been measured directly. A model-based assumption is used here for the spectrum, but the results of future measurements can be incorporated easily. The resulting expression for the coronal heating rate is self-contained, computationally efficient, and applicable directly to global models of the corona and heliosphere. This paper tests and validates the approximations by comparing the results to exact solutions of the wave transport equations in several cases relevant to the fast and slow solar wind.

  5. Rarefaction Effects in Hypersonic Aerodynamics

    NASA Astrophysics Data System (ADS)

    Riabov, Vladimir V.

    2011-05-01

    The Direct Simulation Monte-Carlo (DSMC) technique is used for numerical analysis of rarefied-gas hypersonic flows near a blunt plate, wedge, two side-by-side plates, disk, torus, and rotating cylinder. The role of various similarity parameters (Knudsen and Mach numbers, geometrical and temperature factors, specific heat ratios, and others) in aerodynamics of the probes is studied. Important kinetic effects that are specific for the transition flow regime have been found: non-monotonic lift and drag of plates, strong repulsive force between side-by-side plates and cylinders, dependence of drag on torus radii ratio, and the reverse Magnus effect on the lift of a rotating cylinder. The numerical results are in a good agreement with experimental data, which were obtained in a vacuum chamber at low and moderate Knudsen numbers from 0.01 to 10.

  6. Experimental determination of the strain and strain rate dependence of the fraction of plastic work converted to heat

    SciTech Connect

    Hodowany, J.; Ravichandran, G.; Rosakis, A.J.

    1995-12-31

    When metals are deformed dynamically, there is insufficient time for heat generated by plastic deformation to be conducted to the surroundings. Thus, the conversion of plastic work into heat at high strain rates can result in significant temperature increases, which contribute to thermal softening, thereby altering a material`s constitutive response. The fraction of plastic work converted to heat represents the strength of the coupling term between temperature and mechanical fields in thermalmechanical problems involving plastic flow. The experimental determination of this constitutive function is important since it is an integral part of the formulation of coupled thermomechanical field equations. This fraction also plays an important role in failure mode characterization for metals deforming at high rates of strain, such as the formation of adiabatic shear bands. This investigation systematically examines the rate of conversion of plastic work to heat in metals under dynamic loading. Temperature was measured in-situ using an array of high speed In-Sb infrared detectors. The plastic work rate and the heat generation rate were determined directly from experimental data. The ratio of heat generation rate to plastic work rate, i.e., the relative rate at which plastic work is converted to heat, was calculated from this data. The functional dependence of this quantity upon strain and strain rate is reported for 1020 steel, 2024 aluminum, Ti-6Al-4V titanium alloy, and C300 maraging steel.

  7. Numerical computation of aerodynamics and heat transfer in a turbine cascade and a turn-around duct using advanced turbulence models

    NASA Technical Reports Server (NTRS)

    Lakshminarayana, B.; Luo, J.

    1993-01-01

    The objective of this research is to develop turbulence models to predict the flow and heat transfer fields dominated by the curvature effect such as those encountered in turbine cascades and turn-around ducts. A Navier-Stokes code has been developed using an explicit Runge-Kutta method with a two layer k-epsilon/ARSM (Algebraic Reynolds Stress Model), Chien's Low Reynolds Number (LRN) k-epsilon model and Coakley's LRN q-omega model. The near wall pressure strain correlation term was included in the ARSM. The formulation is applied to Favre-averaged N-S equations and no thin-layer approximations are made in either the mean flow or turbulence transport equations. Anisotropic scaling of artificial dissipation terms was used. Locally variable timestep was also used to improve convergence. Detailed comparisons were made between computations and data measured in a turbine cascade by Arts et al. at Von Karman Institute. The surface pressure distributions and wake profiles were predicted well by all the models. The blade heat transfer is predicted well by k-epsilon/ARSM model, as well as the k-epsilon model. It's found that the onset of boundary layer transition on both surfaces is highly dependent upon the level of local freestream turbulence intensity, which is strongly influenced by the streamline curvature. Detailed computation of the flow in the turn around duct has been carried out and validated against the data by Monson as well as Sandborn. The computed results at various streamwise locations both on the concave and convex sides are compared with flow and turbulence data including the separation zone on the inner well. The k-epsilon/ARSM model yielded relatively better results than the two-equation turbulence models. A detailed assessment of the turbulence models has been made with regard to their applicability to curved flows.

  8. Aerodynamics of thrust vectoring

    NASA Technical Reports Server (NTRS)

    Tseng, J. B.; Lan, C. Edward

    1989-01-01

    Thrust vectoring as a means to enhance maneuverability and aerodynamic performane of a tactical aircraft is discussed. This concept usually involves the installation of a multifunction nozzle. With the nozzle, the engine thrust can be changed in direction without changing the attitude of the aircraft. Change in the direction of thrust induces a significant change in the aerodynamic forces on the aircraft. Therefore, this device can be used for lift-augmenting as well as stability and control purposes. When the thrust is deflected in the longitudinal direction, the lift force and the pitching stability can be manipulated, while the yawing stability can be controlled by directing the thrust in the lateral direction.

  9. Computational aerodynamics and design

    NASA Technical Reports Server (NTRS)

    Ballhaus, W. F., Jr.

    1982-01-01

    The role of computational aerodynamics in design is reviewed with attention given to the design process; the proper role of computations; the importance of calibration, interpretation, and verification; the usefulness of a given computational capability; and the marketing of new codes. Examples of computational aerodynamics in design are given with particular emphasis on the Highly Maneuverable Aircraft Technology. Finally, future prospects are noted, with consideration given to the role of advanced computers, advances in numerical solution techniques, turbulence models, complex geometries, and computational design procedures. Previously announced in STAR as N82-33348

  10. Computational aerodynamics and design

    NASA Technical Reports Server (NTRS)

    Ballhaus, W. F., Jr.

    1982-01-01

    The role of computational aerodynamics in design is reviewed with attention given to the design process; the proper role of computations; the importance of calibration, interpretation, and verification; the usefulness of a given computational capability; and the marketing of new codes. Examples of computational aerodynamics in design are given with particular emphasis on the Highly Maneuverable Aircraft Technology. Finally, future prospects are noted, with consideration given to the role of advanced computers, advances in numerical solution techniques, turbulence models, complex geometries, and computational design procedures. Previously announced in STAR as N82-33348

  11. Nonlinear aerodynamic wing design

    NASA Technical Reports Server (NTRS)

    Bonner, Ellwood

    1985-01-01

    The applicability of new nonlinear theoretical techniques is demonstrated for supersonic wing design. The new technology was utilized to define outboard panels for an existing advanced tactical fighter model. Mach 1.6 maneuver point design and multi-operating point compromise surfaces were developed and tested. High aerodynamic efficiency was achieved at the design conditions. A corollary result was that only modest supersonic penalties were incurred to meet multiple aerodynamic requirements. The nonlinear potential analysis of a practical configuration arrangement correlated well with experimental data.

  12. Two-Dimensional Shape Optimization of Hypersonic Vehicles Considering Transonic Aerodynamic Performance

    NASA Astrophysics Data System (ADS)

    Ueno, Atsushi; Suzuki, Kojiro

    For the success of hypersonic vehicles, their shape must be optimized to achieve a high lift-to-drag ratio as well as a low aerodynamic heating rate in the hypersonic regime. In addition, the transonic lift-to-drag ratio must also be optimized to realize quick acceleration to the hypersonic cruise speed. The three-dimensional lift-to-drag ratio can be improved even by the two-dimensional section shape (i.e., airfoil) optimization in the region where the sweep back angle is small. Here, prior to three-dimensional shape optimization, a study is done to optimize airfoils of hypersonic vehicles based on these three parameters. At optimization, the hypersonic lift-to-drag ratio is maximized while the transonic lift-to-drag ratio and the aerodynamic heating rate are constrained. The optimum lift coefficient for hypersonic cruise at the maximum lift-to-drag ratio is investigated. The relation between the leading edge radius, which determines the aerodynamic heating rate, and the hypersonic lift-to-drag ratio is also investigated. Results show that to improve the hypersonic lift-to-drag ratio, the airfoil thickness around the leading edge should be small as long as an appropriate compromise with the transonic lift-to-drag ratio is achieved. Results also show that the optimum lift coefficient for hypersonic cruise is much lower than that for typical supersonic vehicles. Small cruise lift coefficient suggests that the wing loading of a hypersonic vehicle should be small. The leading edge radius should be determined by a compromise between the hypersonic lift-to-drag ratio and leading edge heating. Airfoil optimization can provide an appropriate initial guess of the three-dimensional optimum shape. By using an appropriate initial guess, the computation time of the three-dimensional shape optimization is expected to be reduced.

  13. Molecular dynamics study on the effect of boundary heating rate on the phase change characteristics of thin film liquid

    SciTech Connect

    Hasan, Mohammad Nasim Morshed, A. K. M. Monjur Rabbi, Kazi Fazle Haque, Mominul

    2016-07-12

    In this study, theoretical investigation of thin film liquid phase change phenomena under different boundary heating rates has been conducted with the help of molecular dynamics simulation. To do this, the case of argon boiling over a platinum surface has been considered. The study has been conducted to get a better understanding of the nano-scale physics of evaporation/boiling for a three phase system with particular emphasis on the effect of boundary heating rate. The simulation domain consisted of liquid and vapor argon atoms placed over a platinum wall. Initially the whole system was brought to an equilibrium state at 90 K with the help of equilibrium molecular dynamics and then the temperature of the bottom wall was increased to a higher temperature (250 K/130 K) over a finite heating period. Depending on the heating period, the boundary heating rate has been varied in the range of 1600×10{sup 9} K/s to 8×10{sup 9} K/s. The variations of argon region temperature, pressure, net evaporation number with respect to time under different boundary heating rates have been determined and discussed. The heat fluxes normal to platinum wall for different cases were also calculated and compared with theoretical upper limit of maximum possible heat transfer to elucidate the effect of boundary heating rate.

  14. Molecular dynamics study on the effect of boundary heating rate on the phase change characteristics of thin film liquid

    NASA Astrophysics Data System (ADS)

    Hasan, Mohammad Nasim; Morshed, A. K. M. Monjur; Rabbi, Kazi Fazle; Haque, Mominul

    2016-07-01

    In this study, theoretical investigation of thin film liquid phase change phenomena under different boundary heating rates has been conducted with the help of molecular dynamics simulation. To do this, the case of argon boiling over a platinum surface has been considered. The study has been conducted to get a better understanding of the nano-scale physics of evaporation/boiling for a three phase system with particular emphasis on the effect of boundary heating rate. The simulation domain consisted of liquid and vapor argon atoms placed over a platinum wall. Initially the whole system was brought to an equilibrium state at 90K with the help of equilibrium molecular dynamics and then the temperature of the bottom wall was increased to a higher temperature (250K/130K) over a finite heating period. Depending on the heating period, the boundary heating rate has been varied in the range of 1600×109 K/s to 8×109 K/s. The variations of argon region temperature, pressure, net evaporation number with respect to time under different boundary heating rates have been determined and discussed. The heat fluxes normal to platinum wall for different cases were also calculated and compared with theoretical upper limit of maximum possible heat transfer to elucidate the effect of boundary heating rate.

  15. Liquid-Phase Heat-Release Rates of the Systems Hydrazine-Nitric Acid and Unsymmetrical Dimethylhydrazine-Nitric Acid

    NASA Technical Reports Server (NTRS)

    Somogyi, Dezso; Feiler, Charles E.

    1960-01-01

    The initial rates of heat release produced by the reactions of hydrazine and unsymmetrical dimethylhydrazine with nitric acid were determined in a bomb calorimeter under conditions of forced mixing. Fuel-oxidant weight ratio and injection velocity were varied. The rate of heat release apparently depended on the interfacial area between the propellants. Above a narrow range of injection velocities representing a critical amount of interfacial area, the rates reached a maximum and were almost constant with injection velocity. The maximum rate for hydrazine was about 70 percent greater than that for unsymmetrical dimethylhydrazine. The total heat released did not vary with mixture ratio over the range studied.

  16. Voyager observations of lower hybrid noise in the Io plasma torus and anomalous plasma heating rates

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.; Coroniti, F. V.; Kurth, W. S.; Scarf, F. L.

    1985-01-01

    A study of Voyager 1 electric field measurements obtained by the plasma wave instrument in the Io plasma torus has been carried out. A survey of the data has revealed the presence of persistent peaks in electric field spectra in the frequency range 100-600 Hz consistent with their identification as lower hybrid noise for a heavy-ion plasma of sulfur and oxygen. Typical wave intensities are 0.1 mV/m, and the spectra also show significant Doppler broadening, Delta omega/omega approximately 1. A theoretical analysis of lower hybrid wave generation by a bump-on-tail ring distribution of ions is given. The model is appropriate for plasmas with a superthermal pickup ion population present. A general methodology is used to demonstrate that the maximum plasma heating rate possible through anomalous wave-particle heat exchange is less than approximately 10 to the -14th ergs per cu cm per s. Although insufficient to meet the power requirement of the EUV-emitting warm torus, the heating rate is large enough to maintain a low-density (0.01-0.1 percent) superthermal electron population of keV electrons, which may lead to a small but significant anomalous ionization effect.

  17. Internal stress-induced melting below melting temperature at high-rate laser heating

    SciTech Connect

    Hwang, Yong Seok; Levitas, Valery I.

    2014-06-30

    In this Letter, continuum thermodynamic and phase field approaches (PFAs) predicted internal stress-induced reduction in melting temperature for laser-irradiated heating of a nanolayer. Internal stresses appear due to thermal strain under constrained conditions and completely relax during melting, producing an additional thermodynamic driving force for melting. Thermodynamic melting temperature for Al reduces from 933.67 K for a stress-free condition down to 898.1 K for uniaxial strain and to 920.8 K for plane strain. Our PFA simulations demonstrated barrierless surface-induced melt nucleation below these temperatures and propagation of two solid-melt interfaces toward each other at the temperatures very close to the corresponding predicted thermodynamic equilibrium temperatures for the heating rate Q≤1.51×10{sup 10}K/s. At higher heating rates, kinetic superheating competes with a reduction in melting temperature and melting under uniaxial strain occurs at 902.1 K for Q = 1.51 × 10{sup 11 }K/s and 936.9 K for Q = 1.46 × 10{sup 12 }K/s.

  18. Kinetic effects on parallel heat flow and ionization rate in divertor plasmas

    NASA Astrophysics Data System (ADS)

    Allais, Fabrice; Kim, Chang-Geun; Alouani Bibi, Fathallah; Matte, Jean-Pierre; Stotler, Daren; Rognlien, Thomas

    2004-11-01

    1-D simulations of parallel heat flow in divertor plasmas, with and without recycling are made with the UEDGE fluid code, comparing runs using classical flux limited heat flow to nonlocal heat transport [1], now implemented in UEDGE. Comparative simulations are made with the electron kinetic code FPI. For the latter, we prescribe the power input source, which emulates cross field transport, to be identical to that of our UEDGE runs. But, the temperature profile computed by FPI is found to depend very strongly on the assumed velocity dependence of this source, even if the integrated power is the same. The atomic hydrogen ionization module in FPI uses cross sections such that, for Maxwellian plasmas, the rates are the same as those used by UEDGE and DEGAS; this is necessary because step-wise ionization is dominant. There is strong enhancement of the total ionization rate (including stepwise ionization) in cold, detached plasmas, due to nonlocal transport effects. [1] F. Alouani Bibi and J.P. Matte, Phys. Rev. E 66, 066414 (2002)

  19. Pressure and heating-rate distributions on a corrugated surface in a supersonic turbulent boundary layer

    NASA Technical Reports Server (NTRS)

    Sawyer, J. W.

    1977-01-01

    Drag and heating rates on wavy surfaces typical of current corrugated plate designs for thermal protection systems were determined experimentally. Pressure-distribution, heating-rate, and oil-flow tests were conducted in the Langley Unitary Plan wind tunnel at Mach numbers of 2.4 and 4.5 with the corrugated surface exposed to both thick and thin turbulent boundary layers. Tests were conducted with the corrugations at cross-flow angles from 0 deg to 90 deg to the flow. Results show that for cross-flow angles of 30 deg or less, the pressure drag coefficients are less than the local flat-plate skin-friction coefficients and are not significantly affected by Mach number, Reynolds number, or boundary-layer thickness over the ranges investigated. For cross-flow angles greater than 30 deg, the drag coefficients increase significantly with cross-flow angle and moderately with Reynolds number. Increasing the Mach number causes a significant reduction in the pressure drag. The average and peak heating penalties due to the corrugated surface are small for cross-flow angles of 10 deg or less but are significantly higher for the larger cross-flow angles.

  20. Effects of NaCl on metabolic heat evolution rates by barley roots

    NASA Technical Reports Server (NTRS)

    Criddle, R. S.; Hansen, L. D.; Breidenbach, R. W.; Ward, M. R.; Huffaker, R. C.

    1989-01-01

    The effect of salinity stress on metabolic heat output of barley (Hordeum vulgare L.) root tips was measured by isothermal microcalorimetry. Several varieties differing in tolerance to salinity were compared and differences quantified. Two levels of inhibition by increasing salt were found. Following the transition from the initial rate of the first level, inhibition remained at about 50% with further increases in salt concentration up to 150 millimolar. The concentration of salt required to inhibit to this level was cultivar dependent. At highter concentrations (>150 millimolar) of salt, metabolism was further decreased. This decrease was not cultivar dependent. The decreased rate of metabolic heat output at the first transition could be correlated with decreases in uptake of NO3-, NH4+, and Pi that occurred as the salt concentration was increased. The high degree of dependence of the inhibition of metabolic heat output on NaCl concentration points to a highly cooperative reaction responsible for the general inhibition of metabolism and nutrient uptake. The time required to attain the first level of salt inhibition is less than 20 minutes. Inhibition of root tips was not reversible by washing with salt free solutions. In addition to revealing these features of salt inhibition, isothermal microcalorimetry is a promising method for convenient and rapid determination of varietal differences in response to increasing salinity.

  1. Additive Effects of Heating and Exercise on Baroreflex Control of Heart Rate in Healthy Males.

    PubMed

    Peçanha, Tiago; Forjaz, Claudia Lucia de Moraes; Low, David Andrew

    2017-08-31

    This study assessed the additive effects of passive heating and exercise on cardiac baroreflex sensitivity (cBRS) and heart rate variability (HRV). Twelve healthy young men (25±1 yrs, 23.8±0.5 kg/m(2)) randomly underwent two experimental sessions: heat stress (HS; whole-body heat stress using a tube-lined suit to increase core temperature by ~1°C) and normothermia (NT). Each session was composed of a: pre-intervention rest (REST1); HS or NT interventions; post-intervention rest (REST2); and 14 min of cycling exercise [7 min at 40%HRreserve (EX1) and 7 min at 60%HRreserve (EX2)]. Heart rate and finger blood pressure were continuously recorded. cBRS was assessed using the sequence (cBRSSEQ) and transfer function (cBRSTF) methods. HRV was assessed using the indices SDNN (standard deviation of RR intervals) and RMSSD (root mean square of successive RR intervals). cBRS and HRV were not different between sessions during EX1 and EX2 (i.e. matched heart rate conditions: EX1=116±3 vs. 114±3, EX2=143±4 vs. 142±3 bpm; but different workloads: EX1=50±9 vs. 114±8, EX2=106±10 vs. 165±8 Watts; for HS and NT, respectively; P<0.01). However, when comparing EX1 of NT with EX2 of HS (i.e. matched workload conditions, but with different heart rates), cBRS and HRV were significantly reduced in HS (cBRSSEQ = 1.6±0.3 vs. 0.6±0.1 ms/mmHg, P<0.01; SDNN = 2.3±0.1 vs. 1.3±0.2 ms, P<0.01). In conclusion, in conditions matched by HR, the addition of heat stress to exercise does not affect cBRS and HRV. Alternatively, in workload-matched conditions, the addition of heat to exercise results in reduced cBRS and HRV compared to exercise in normothermia. Copyright © 2017, Journal of Applied Physiology.

  2. Accurate label-free reaction kinetics determination using initial rate heat measurements

    PubMed Central

    Ebrahimi, Kourosh Honarmand; Hagedoorn, Peter-Leon; Jacobs, Denise; Hagen, Wilfred R.

    2015-01-01

    Accurate label-free methods or assays to obtain the initial reaction rates have significant importance in fundamental studies of enzymes and in application-oriented high throughput screening of enzyme activity. Here we introduce a label-free approach for obtaining initial rates of enzyme activity from heat measurements, which we name initial rate calorimetry (IrCal). This approach is based on our new finding that the data recorded by isothermal titration calorimetry for the early stages of a reaction, which have been widely ignored, are correlated to the initial rates. Application of the IrCal approach to various enzymes led to accurate enzyme kinetics parameters as compared to spectroscopic methods and enabled enzyme kinetic studies with natural substrate, e.g. proteases with protein substrates. Because heat is a label-free property of almost all reactions, the IrCal approach holds promise in fundamental studies of various enzymes and in use of calorimetry for high throughput screening of enzyme activity. PMID:26574737

  3. Extension of the master sintering curve for constant heating rate modeling

    NASA Astrophysics Data System (ADS)

    McCoy, Tammy Michelle

    The purpose of this work is to extend the functionality of the Master Sintering Curve (MSC) such that it can be used as a practical tool for predicting sintering schemes that combine both a constant heating rate and an isothermal hold. Rather than just being able to predict a final density for the object of interest, the extension to the MSC will actually be able to model a sintering run from start to finish. Because the Johnson model does not incorporate this capability, the work presented is an extension of what has already been shown in literature to be a valuable resource in many sintering situations. A predicted sintering curve that incorporates a combination of constant heating rate and an isothermal hold is more indicative of what is found in real-life sintering operations. This research offers the possibility of predicting the sintering schedule for a material, thereby having advanced information about the extent of sintering, the time schedule for sintering, and the sintering temperature with a high degree of accuracy and repeatability. The research conducted in this thesis focuses on the development of a working model for predicting the sintering schedules of several stabilized zirconia powders having the compositions YSZ (HSY8), 10Sc1CeSZ, 10Sc1YSZ, and 11ScSZ1A. The compositions of the four powders are first verified using x-ray diffraction (XRD) and the particle size and surface area are verified using a particle size analyzer and BET analysis, respectively. The sintering studies were conducted on powder compacts using a double pushrod dilatometer. Density measurements are obtained both geometrically and using the Archimedes method. Each of the four powders is pressed into ¼" diameter pellets using a manual press with no additives, such as a binder or lubricant. Using a double push-rod dilatometer, shrinkage data for the pellets is obtained over several different heating rates. The shrinkage data is then converted to reflect the change in relative

  4. Identification of aerodynamic models for maneuvering aircraft

    NASA Technical Reports Server (NTRS)

    Lan, C. Edward; Hu, C. C.

    1992-01-01

    A Fourier analysis method was developed to analyze harmonic forced-oscillation data at high angles of attack as functions of the angle of attack and its time rate of change. The resulting aerodynamic responses at different frequencies are used to build up the aerodynamic models involving time integrals of the indicial type. An efficient numerical method was also developed to evaluate these time integrals for arbitrary motions based on a concept of equivalent harmonic motion. The method was verified by first using results from two-dimensional and three-dimensional linear theories. The developed models for C sub L, C sub D, and C sub M based on high-alpha data for a 70 deg delta wing in harmonic motions showed accurate results in reproducing hysteresis. The aerodynamic models are further verified by comparing with test data using ramp-type motions.

  5. Bat flight generates complex aerodynamic tracks.

    PubMed

    Hedenström, A; Johansson, L C; Wolf, M; von Busse, R; Winter, Y; Spedding, G R

    2007-05-11

    The flapping flight of animals generates an aerodynamic footprint as a time-varying vortex wake in which the rate of momentum change represents the aerodynamic force. We showed that the wakes of a small bat species differ from those of birds in some important respects. In our bats, each wing generated its own vortex loop. Also, at moderate and high flight speeds, the circulation on the outer (hand) wing and the arm wing differed in sign during the upstroke, resulting in negative lift on the hand wing and positive lift on the arm wing. Our interpretations of the unsteady aerodynamic performance and function of membranous-winged, flapping flight should change modeling strategies for the study of equivalent natural and engineered flying devices.

  6. Computer graphics in aerodynamic analysis

    NASA Technical Reports Server (NTRS)

    Cozzolongo, J. V.

    1984-01-01

    The use of computer graphics and its application to aerodynamic analyses on a routine basis is outlined. The mathematical modelling of the aircraft geometries and the shading technique implemented are discussed. Examples of computer graphics used to display aerodynamic flow field data and aircraft geometries are shown. A future need in computer graphics for aerodynamic analyses is addressed.

  7. Technology and operational considerations for low-heat-rate trajectories. [of future winged earth reentry vehicles

    NASA Technical Reports Server (NTRS)

    Wurster, K. E.; Eldred, C. H.

    1979-01-01

    A broad parametric study which examines several critical aspects of low-heat-rate entry trajectories is performed. Low planform loadings associated with future winged earth-entry vehicles coupled with the potential application of metallic thermal protection systems (TPS) suggest that such trajectories are of particular interest. Studied are three heating conditions - reference, stagnation, and windward centerline, for both laminar and turbulent flow; configuration-related factors including planform loading and hypersonic angle of attack; and mission-related factors such as cross-range and orbit inclination. Results indicate benefits in the design of TPS to be gained by utilizing moderate angles of attack as opposed to high-lift coefficient, high angles of attack, during entry. An assessment of design and technology implications is made.

  8. Heat production rate from radioactive elements in igneous and metamorphic rocks in Eastern Desert, Egypt.

    PubMed

    Abbady, Adel G E; El-Arabi, A M; Abbady, A

    2006-01-01

    Radioactive heat-production data of Igneous and Metamorphic outcrops in the Eastern Desert are presented. Samples were analysed using a low level gamma-ray spectrometer (HPGe) in the laboratory. A total of 205 rock samples were investigated, covering all major rock types of the area. The heat-production rate of igneous rocks ranges from 0.11 (basalt) to 9.53 microWm(-3) (granite). In metamorphic rocks it varies from 0.28 (serpentinite ) to 0.91 microWm(-3) (metagabbro). The contribution due to U is about 51%, as that from Th is 31% and 18% from K. The corresponding values in igneous rocks are 76%, 19% and 5%, respectively. The calculated values showed good agreement with global values except in some areas containing granites.

  9. High-rate laser metal deposition of Inconel 718 component using low heat-input approach

    NASA Astrophysics Data System (ADS)

    Kong, C. Y.; Scudamore, R. J.; Allen, J.

    Currently many aircraft and aero engine components are machined from billets or oversize forgings. This involves significant cost, material wastage, lead-times and environmental impacts. Methods to add complex features to another component or net-shape surface would offer a substantial cost benefit. Laser Metal Deposition (LMD), currently being applied to the repair of worn or damaged aero engine components, was attempted in this work as an alternative process route, to build features onto a base component, because of its low heat input capability. In this work, low heat input and high-rate deposition was developed to deposit Inconel 718 powder onto thin plates. Using the optimised process parameters, a number of demonstrator components were successfully fabricated.

  10. Approximate method for calculating heating rates on three-dimensional vehicles

    NASA Astrophysics Data System (ADS)

    Hamilton, H. Harris; Greene, Francis A.; Dejarnette, F. R.

    1994-05-01

    An approximate method for calculating heating rates on three-dimensional vehicles at angle of attack is presented. The method is based on the axisymmetric analog for three-dimensional boundary layers and uses a generalized body-fitted coordinate system. Edge conditions for the boundary-layer solution are obtained from an inviscid flowfield solution, and because of the coordinate system used, the method is applicable to any blunt body geometry for which an inviscid flowfield solution can be obtained. The method is validated by comparing with experimental heating data and with thin-layer Navier-Stokes calculations on the shuttle orbiter at both wind-tunnel and flight conditions and with thin-layer Navier-Stokes calculations on the HL-20 at wind-tunnel conditions.

  11. An approximate method for calculating heating rates on three-dimensional vehicles

    NASA Technical Reports Server (NTRS)

    Hamilton, H. H., II; Greene, Francis A.; Dejarnette, Fred R.

    1993-01-01

    An approximate method for calculating heating rates on three-dimensional vehicles at angle of attack is presented. The method is based on the axisymmetric analog for three-dimensional boundary layers and uses a generalized body fitted coordinate system. Edge conditions for the boundary layer solution are obtained from an inviscid flowfield solution, and because of the coordinate system used the method is applicable to any blunt body geometry for which a inviscid flowfield solution can be obtained. It is validated by comparing with experimental heating data and with Navier-Stokes calculations on the Shuttle orbiter at both wind tunnel and flight conditions and with Navier-Stokes calculations on the HL-20 at wind tunnel conditions.

  12. Approximate method for calculating heating rates on three-dimensional vehicles

    NASA Technical Reports Server (NTRS)

    Hamilton, H. Harris; Greene, Francis A.; Dejarnette, F. R.

    1994-01-01

    An approximate method for calculating heating rates on three-dimensional vehicles at angle of attack is presented. The method is based on the axisymmetric analog for three-dimensional boundary layers and uses a generalized body-fitted coordinate system. Edge conditions for the boundary-layer solution are obtained from an inviscid flowfield solution, and because of the coordinate system used, the method is applicable to any blunt body geometry for which an inviscid flowfield solution can be obtained. The method is validated by comparing with experimental heating data and with thin-layer Navier-Stokes calculations on the shuttle orbiter at both wind-tunnel and flight conditions and with thin-layer Navier-Stokes calculations on the HL-20 at wind-tunnel conditions.

  13. Approximate method for calculating heating rates on three-dimensional vehicles

    NASA Technical Reports Server (NTRS)

    Hamilton, H. Harris; Greene, Francis A.; Dejarnette, F. R.

    1994-01-01

    An approximate method for calculating heating rates on three-dimensional vehicles at angle of attack is presented. The method is based on the axisymmetric analog for three-dimensional boundary layers and uses a generalized body-fitted coordinate system. Edge conditions for the boundary-layer solution are obtained from an inviscid flowfield solution, and because of the coordinate system used, the method is applicable to any blunt body geometry for which an inviscid flowfield solution can be obtained. The method is validated by comparing with experimental heating data and with thin-layer Navier-Stokes calculations on the shuttle orbiter at both wind-tunnel and flight conditions and with thin-layer Navier-Stokes calculations on the HL-20 at wind-tunnel conditions.

  14. An approximate method for calculating heating rates on three-dimensional vehicles

    NASA Technical Reports Server (NTRS)

    Hamilton, H. H., II; Greene, Francis A.; Dejarnette, Fred R.

    1993-01-01

    An approximate method for calculating heating rates on three-dimensional vehicles at angle of attack is presented. The method is based on the axisymmetric analog for three-dimensional boundary layers and uses a generalized body fitted coordinate system. Edge conditions for the boundary layer solution are obtained from an inviscid flowfield solution, and because of the coordinate system used the method is applicable to any blunt body geometry for which a inviscid flowfield solution can be obtained. It is validated by comparing with experimental heating data and with Navier-Stokes calculations on the Shuttle orbiter at both wind tunnel and flight conditions and with Navier-Stokes calculations on the HL-20 at wind tunnel conditions.

  15. Radial Pressure Pulse and Heart Rate Variability in Heat- and Cold-Stressed Humans

    PubMed Central

    Huang, Chin-Ming; Chang, Hsien-Cheh; Kao, Shung-Te; Li, Tsai-Chung; Wei, Ching-Chuan; Chen, Chiachung; Liao, Yin-Tzu; Chen, Fun-Jou

    2011-01-01

    This study aims to explore the effects of heat and cold stress on the radial pressure pulse (RPP) and heart rate variability (HRV). The subjects immersed their left hand into 45°C and 7°C water for 2 minutes. Sixty healthy subjects (age 25 ± 4 yr; 29 men and 31 women) were enrolled in this study. All subjects underwent the supine temperature measurements of the bilateral forearms, brachial arterial blood pressure, HRV and RPP with a pulse analyzer in normothermic conditions, and thermal stresses. The power spectral low-frequency (LF) and high-frequency (HF) components of HRV decreased in the heat test and increased in the cold test. The heat stress significantly reduced radial augmentation index (AIr) (P < .05), but the cold stress significantly increased AIr (P < .01). The spectral energy of RPP did not show any statistical difference in 0 ~ 10 Hz region under both conditions, but in the region of 10 ~ 50 Hz, there was a significant increase (P < .01) in the heat test and a significant decrease in the cold test (P < .01). The changes in AIr induced by heat and cold stress were significantly negatively correlated with the spectral energy in the region of 10 ~ 50 Hz (SE10−50 Hz) but not in the region of 0 ~ 10 Hz (SE0−10 Hz). The results demonstrated that the SE10−50 Hz, which only possessed a small percentage in total pulse energy, presented more physiological characteristics than the SE0−10 Hz under the thermal stresses. PMID:21113292

  16. Influence of Steel Grade on Surface Cooling Rates and Heat Flux during Quenching

    NASA Astrophysics Data System (ADS)

    Prasanna Kumar, T. S.

    2013-07-01

    Immersion quenching is one of the most widely used processes for achieving martensitic and bainitic steels. The efficiency and quality of quenching are generally tested using standard quench probes for obtaining the cooling curves. A host of parameters like quenchant type, steel grade, bath agitation, section thickness, etc., affect the cooling curves. Cooling curve analyses covered under ASTM standards cannot be used to assess the performance of a quenchant for different grades of steel, as they use a common material for the probe. This article reports the development of equipment, which, in conjunction with mathematical models, can be used for obtaining cooling curves for a specific steel/quenchant combination. The mathematical models couple nonlinear transient inverse heat transfer with phase transformation, resulting in cooling curves specific to the steel grade-quenchant combination. The austenite decomposition models were based on an approach consistent with both the TTT diagram of the steel and Fe-C equilibrium phase diagrams. The TTT diagrams for the specific chemistry of the specimens and the thermophysical properties of the individual phases as functions of temperature were obtained using JMatPro software. Experiments were conducted in the laboratory for computing surface temperature and heat flux at the mid-section of a 25-mm diameter by 100-mm-long cylindrical specimen of two types of steels in two different quenchants. A low alloy steel (EN19) and a plain carbon steel (C45) were used for bringing out the influence of austenite transformation on surface cooling rates and heat flux. Two types of industrial quenchants (i) a mineral oil, and (ii) an aqueous solution of polymer were used. The results showed that the cooling curves, cooling rate curves, and the surface heat flux depended on the steel grade with the quenchant remaining the same.

  17. Stage-specific heat effects: timing and duration of heat waves alter demographic rates of a global insect pest.

    PubMed

    Zhang, Wei; Rudolf, Volker H W; Ma, Chun-Sen

    2015-12-01

    The frequency and duration of periods with high temperatures are expected to increase under global warming. Thus, even short-lived organisms are increasingly likely to experience periods of hot temperatures at some point of their life-cycle. Despite recent progress, it remains unclear how various temperature experiences during the life-cycle of organisms affect demographic traits. We simulated hot days (daily mean temperature of 30 °C) increasingly experienced under field conditions and investigated how the timing and duration of such hot days during the life cycle of Plutella xylostella affects adult traits. We show that hot days experienced during some life stages (but not all) altered adult lifespan, fecundity, and oviposition patterns. Importantly, the effects of hot days were contingent on which stage was affected, and these stage-specific effects were not always additive. Thus, adults that experience different temporal patterns of hot periods (i.e., changes in timing and duration) during their life-cycle often had different demographic rates and reproductive patterns. These results indicate that we cannot predict the effects of current and future climate on natural populations by simply focusing on changes in the mean temperature. Instead, we need to incorporate the temporal patterns of heat events relative to the life-cycle of organisms to describe population dynamics and how they will respond to future climate change.

  18. Extreme learning machine: a new alternative for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters.

    PubMed

    Liu, Zhijian; Li, Hao; Tang, Xindong; Zhang, Xinyu; Lin, Fan; Cheng, Kewei

    2016-01-01

    Heat collection rate and heat loss coefficient are crucial indicators for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, the direct determination requires complex detection devices and a series of standard experiments, wasting too much time and manpower. To address this problem, we previously used artificial neural networks and support vector machine to develop precise knowledge-based models for predicting the heat collection rates and heat loss coefficients of water-in-glass evacuated tube solar water heaters, setting the properties measured by "portable test instruments" as the independent variables. A robust software for determination was also developed. However, in previous results, the prediction accuracy of heat loss coefficients can still be improved compared to those of heat collection rates. Also, in practical applications, even a small reduction in root mean square errors (RMSEs) can sometimes significantly improve the evaluation and business processes. As a further study, in this short report, we show that using a novel and fast machine learning algorithm-extreme learning machine can generate better predicted results for heat loss coefficient, which reduces the average RMSEs to 0.67 in testing.

  19. Design and simulation of heat exchangers using Aspen HYSYS, and Aspen exchanger design and rating for paddy drying application

    NASA Astrophysics Data System (ADS)

    Janaun, J.; Kamin, N. H.; Wong, K. H.; Tham, H. J.; Kong, V. V.; Farajpourlar, M.

    2016-06-01

    Air heating unit is one of the most important parts in paddy drying to ensure the efficiency of a drying process. In addition, an optimized air heating unit does not only promise a good paddy quality, but also save more for the operating cost. This study determined the suitable and best specifications heating unit to heat air for paddy drying in the LAMB dryer. In this study, Aspen HYSYS v7.3 was used to obtain the minimum flow rate of hot water needed. The resulting data obtained from Aspen HYSYS v7.3 were used in Aspen Exchanger Design and Rating (EDR) to generate heat exchanger design and costs. The designs include shell and tubes and plate heat exchanger. The heat exchanger was designed in order to produce various drying temperatures of 40, 50, 60 and 70°C of air with different flow rate, 300, 2500 and 5000 LPM. The optimum condition for the heat exchanger were found to be plate heat exchanger with 0.6 mm plate thickness, 198.75 mm plate width, 554.8 mm plate length and 11 numbers of plates operating at 5000 LPM air flow rate.

  20. Advanced propeller aerodynamic analysis

    NASA Technical Reports Server (NTRS)

    Bober, L. J.

    1980-01-01

    The analytical approaches as well as the capabilities of three advanced analyses for predicting propeller aerodynamic performance are presented. It is shown that two of these analyses use a lifting line representation for the propeller blades, and the third uses a lifting surface representation.

  1. Aerodynamics of Race Cars

    NASA Astrophysics Data System (ADS)

    Katz, Joseph

    2006-01-01

    Race car performance depends on elements such as the engine, tires, suspension, road, aerodynamics, and of course the driver. In recent years, however, vehicle aerodynamics gained increased attention, mainly due to the utilization of the negative lift (downforce) principle, yielding several important performance improvements. This review briefly explains the significance of the aerodynamic downforce and how it improves race car performance. After this short introduction various methods to generate downforce such as inverted wings, diffusers, and vortex generators are discussed. Due to the complex geometry of these vehicles, the aerodynamic interaction between the various body components is significant, resulting in vortex flows and lifting surface shapes unlike traditional airplane wings. Typical design tools such as wind tunnel testing, computational fluid dynamics, and track testing, and their relevance to race car development, are discussed as well. In spite of the tremendous progress of these design tools (due to better instrumentation, communication, and computational power), the fluid dynamic phenomenon is still highly nonlinear, and predicting the effect of a particular modification is not always trouble free. Several examples covering a wide range of vehicle shapes (e.g., from stock cars to open-wheel race cars) are presented to demonstrate this nonlinear nature of the flow field.

  2. Aerodynamics of the Cyclogyro

    NASA Astrophysics Data System (ADS)

    Iosilevski, Gil; Levy, Yuval; Weihs, Daniel

    2001-11-01

    The Cyclogiro is the name given by NASA researchers in the '30s to an aerodynamic configuration of several large aspect ratio rectangular airfoils with horizontal span, placed on the circumference of a vertical circle of radius of the order of the airfoil chord, and rotating around the circle center at high speed, with periodically changing angle of attack. This configuration produces aerodynamic forces that can be applied to lift and thrust, depending on the phase angle between the instantaneous position and angle of attack. The original approach was to install such rotors instead of an aircraft wing, and thus combine the lift & thrust producing functions. As a result of the state of knowledge of unsteady aerodynamics at the time disparities between predictions and measured forces remained unexplained. This, combined with low efficiency resulted in the concept being abandoned. In the present study the concept is revisited, as a possible propulsor/lift generator for a hover-capable micro-UAV. Preliminary analysis showed that scaling down to rotor airfoil sizes of 10-15 cm span and 2 cm chord will reduce the centrifugal forces to manageable proportions while the aerodynamic forces would be comparable to those obtained by conventional rotors. A series of experiments was performed, showing disparities of up to 30theory. Visualization showed that this difference resulted mainly from interactions between single foil wakes with the following foils, and a numerical study confirmed the magnitude of the effects, in good agreement with the experiments.

  3. Calculations of Solar Shortwave Heating Rates due to Black Carbon and Ozone Absorption Using in Situ Measurements

    NASA Technical Reports Server (NTRS)

    Gao, R. S.; Hall, S. R.; Swartz, W. H.; Spackman, J. R.; Watts, L. A.; Fahey, D. W.; Aikin, K. C.; Shetter, R. E.; Bui, T. P.

    2008-01-01

    Results for the solar heating rates in ambient air due to absorption by black-carbon (BC) containing particles and ozone are presented as calculated from airborne observations made in the tropical tropopause layer (TTL) in January-February 2006. The method uses airborne in situ observations of BC particles, ozone and actinic flux. Total BC mass is obtained along the flight track by summing the masses of individually detected BC particles in the range 90 to 600-nm volume-equivalent diameter, which includes most of the BC mass. Ozone mixing ratios and upwelling and partial downwelling solar actinic fluxes were measured concurrently with BC mass. Two estimates used for the BC wavelength-dependent absorption cross section yielded similar heating rates. For mean altitudes of 16.5, 17.5, and 18.5 km (0.5 km) in the tropics, average BC heating rates were near 0.0002 K/d. Observed BC coatings on individual particles approximately double derived BC heating rates. Ozone heating rates exceeded BC heating rates by approximately a factor of 100 on average and at least a factor of 4, suggesting that BC heating rates in this region are negligible in comparison.

  4. Effect of heating rate on thermal cracking characteristics and kinetics of Xinjiang oil sand bitumen by TG-FTIR

    NASA Astrophysics Data System (ADS)

    Hao, Junhui; Zhang, Jinhong; Qiao, Yingyun; Tian, Yuanyu

    2017-08-01

    This work was aimed to investigate effects of heating rate on thermal cracking behaviors, distribution of gaseous products and activation energy of the thermal cracking process of Xinjiang oil sand bitumen (OSB). The thermal cracking experiments of Xinjiang OSB were performed by using thermogravimetric analyzer (TGA) at various heating rates of 10, 20, 50, 80 and 120 K/min. The evolving characteristic of gaseous products produced from the thermal cracking process was evaluated by the Fourier transform infrared spectrometry (FTIR) connected with TG. The kinetic parameters of the thermal cracking process of Xinjiang OSB at each of heating rate were determined by the Coats-Redfern model. The result show that the temperature intervals of DE volatilization stage and main reaction stage, the ((dw/dt) max and Tmax in thermal cracking process of Xinjiang OSB all increased with the increasing heating rate. While the heating rate has not obvious effect on the coke yield of Xinjiang OSB. Furthermore, the maximum absorbance of gaseous products and corresponding temperature became larger as the heating rate increases. The activation energy of this two stage both presented increasing trend with the rising heating rate, while the increasing content of that of DE volatilization stage was weaker compared to that of main reaction stage.

  5. Measurements of the heat release rate integral in turbulent premixed stagnation flames with particle image velocimetry

    SciTech Connect

    Chen, Yung-Cheng; Kim, Munki; Han, Jeongjae; Yun, Sangwook; Yoon, Youngbin

    2008-08-15

    A new definition of turbulent consumption speed is proposed in this work that is based on the heat release rate integral, rather than the mass burning rate integral. Its detailed derivation and the assumptions involved are discussed in a general context that applies to all properly defined reaction progress variables. The major advantage of the proposed definition is that it does not require the thin-flame assumption, in contrast to previous definitions. Experimental determination of the local turbulent displacement speed, S{sub D}, and the local turbulent consumption speed, S{sub C}, is also demonstrated with the particle image velocimetry technique in three turbulent premixed stagnation flames. The turbulence intensity of these flames is of the same order of the laminar burning velocity. Based on the current data, a model equation for the local mean heat release rate is proposed. The relationship between S{sub D} and S{sub C} is discussed along with a possible modeling approach for the turbulent displacement speed. (author)

  6. Specific heat flow rate: an on-line monitor and potential control variable of specific metabolic rate in animal cell culture that combines microcalorimetry with dielectric spectroscopy.

    PubMed

    Guan, Y; Evans, P M; Kemp, R B

    1998-06-05

    One of the requirements for enhanced productivity by the animal culture systems used in biotechnology is the direct assessment of the metabolic rate by on-line biosensors. Based on the fact that cell growth is associated with an enthalpy change, it is shown that the specific heat flow rate is stoichiometrically related to the net specific rates of substrates, products, and indeed to specific growth rate, and therefore a direct reflection of metabolic rate. Heat flow rate measured by conduction calorimetry has a technical advantage over estimates for many material flows which require assays at a minimum of two discrete times to give the rate. In order to make heat flow rate specific to the amount of the living cellular system, it would be advantageous to divide it by viable biomass. This requirement has been fulfilled by combining a continuous flow microcalorimeter ex situ with a dielectric spectroscope in situ, the latter measuring the viable cell mass volume fraction. The quality of the resulting biosensor for specific heat flow rate was illustrated using batch cultures of Chinese hamster ovary cells (CHO 320) producing recombinant human interferon-gamma (IFN-gamma) during growth in a stirred tank bioreactor under fully aerobic conditions. The measuring scatter of the probe was decreased significantly by applying the moving average technique to the two participant signals. It was demonstrated that the total metabolic rate of the cells, as indicated by the specific heat flow rate sensor, decreased with increasing time in batch culture, coincident with the decline in the two major substrates, glucose and glutamine, and the accumulation of the by-products, ammonia and lactate. Furthermore, the specific heat flow rate was an earlier indicator of substrate depletion than the flow rate alone. The calorimetric-respirometric ratio showed the intensive participation of anaerobic processes during growth and the related IFN-gamma production. Specific heat flow rate was

  7. Experimental aerodynamic heating to simulated space shuttle tiles in laminar and turbulent boundary layers with variable flow angles at a nominal Mach number of 7. M.S. Thesis - George Washington Univ., Nov. 1983

    NASA Technical Reports Server (NTRS)

    Avery, D. E.

    1985-01-01

    The heat transfer to simulated shuttle thermal protection system tiles was investigated experimentally by using a highly instrumented metallic thin wall tile arranged with other metal tiles in a staggered tile array. Cold wall heating rate data for laminar and turbulent flow were obtained in the Langley 8 foot high Temperature Tunnel at a nominal Mach number of 7, a nominal total temperature of 3300R, a free stream unit Reynolds number from 3.4 x 10 sup 5 to 2.2 10 sup 6 per foot, and a free stream dynamic pressure from 2.1 to 9.0 psia. Experimental data are presented to illustrate the effects of flow angularity and gap width on both local peak heating and overall heating loads. For the conditions of the present study, the results show that localized and total heating are sensitive to changes in flow angle only for the test conditions of turbulent boundary layer flow with high kinetic energy and that a flow angle from 30 deg to 50 deg will minimize the local heating.

  8. Promotion of melt-assisted growth in Bi-2223 tapes utilizing rapid heating rates

    NASA Astrophysics Data System (ADS)

    Avgeros, S.; Al-Mosawi, M.; Young, E. A.; Yang, Y.

    2005-04-01

    Recent differential thermal analysis studies on green Bi-2223 tapes showed two phase transitions, with onset temperatures 800 and 820 °C. From microstructural examination of the long-term phase formation in the tapes the higher temperature endotherm was associated with a partial melt. In this study it is demonstrated how control of the heating rate can promote the partial melt (characterized by DTA), and thereby improve the transport current, Ic. XRD, SEM and transport measurements in field show microstructure features typical of an increased volume of liquid phase: a reduction in secondary phase volume and pores with a corresponding increase in c-plane texture.

  9. Effect of heating rate on toxicity of pyrolysis gases from some synthetic polymers

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Soriano, J. A.; Kosola, K. L.

    1977-01-01

    The effect of heating rate on the toxicity of the pyrolysis gases from some synthetic polymers was investigate, using a screening test method. The synthetic polymers were polyethylene, polystyrene, polymethyl methacrylate, polycarbonate, ABS, polyaryl sulfone, polyether sulfone, and polyphenylene sulfide. The toxicants from the sulfur-containing polymers appeared to act more rapidly than the toxicants from the other polymers. It is not known whether this effect is due primarily to differences in concentration or in the nature of the toxicants. The carbon monoxide concentrations found do not account for the observed results.

  10. Effect of heating rate on toxicity of pyrolysis gases from some elastomers

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Kosola, K. L.; Solis, A. N.

    1977-01-01

    The effect of heating rate on the toxicity of the pyrolysis gases from six elastomers was investigated, using a screening test method. The elastomers were polyisoprene (natural rubber), styrene-butadiene rubber (SBR), ethylene propylene diene terpolymer (EPDM), acrylonitrile rubber, chlorosulfonated polyethylene rubber, and polychloroprene. The rising temperature and fixed temperature programs produced exactly the same rank order of materials based on time to death. Acrylonitrile rubber exhibited the greatest toxicity under these test conditions, and carbon monoxide was not found in sufficient concentrations to be the primary cause of death.

  11. Global distribution of moisture, evaporation-precipitation, and diabatic heating rates

    NASA Technical Reports Server (NTRS)

    Christy, John R.

    1989-01-01

    Global archives were established for ECMWF 12-hour, multilevel analysis beginning 1 January 1985; day and night IR temperatures, and solar incoming and solar absorbed. Routines were written to access these data conveniently from NASA/MSFC MASSTOR facility for diagnostic analysis. Calculations of diabatic heating rates were performed from the ECMWF data using 4-day intervals. Calculations of precipitable water (W) from 1 May 1985 were carried out using the ECMWF data. Because a major operational change on 1 May 1985 had a significant impact on the moisture field, values prior to that date are incompatible with subsequent analyses.

  12. Simultaneous optimization of the cavity heat load and trip rates in linacs using a genetic algorithm

    DOE PAGES

    Terzić, Balša; Hofler, Alicia S.; Reeves, Cody J.; ...

    2014-10-15

    In this paper, a genetic algorithm-based optimization is used to simultaneously minimize two competing objectives guiding the operation of the Jefferson Lab's Continuous Electron Beam Accelerator Facility linacs: cavity heat load and radio frequency cavity trip rates. The results represent a significant improvement to the standard linac energy management tool and thereby could lead to a more efficient Continuous Electron Beam Accelerator Facility configuration. This study also serves as a proof of principle of how a genetic algorithm can be used for optimizing other linac-based machines.

  13. Sensitivity of shortwave radiative flux density, forcing, and heating rates to the aerosol vertical profile

    SciTech Connect

    Guan, Hong; Schmid, Beat; Bucholtz, Anthony; Bergstrom, Robert

    2010-03-31

    The effect of the aerosol vertical distribution on the solar radiation profiles, for idealized and measured profiles of optical properties (extinction and single-scattering albedo (SSA)) during the May 2003 Atmospheric Radiation Measurement (ARM) Aerosol Intensive Observation Period (AIOP), has been investigated using the Rapid Radiative Transfer Model Shortwave (RRTM_SW) code. Calculated profiles of down-welling and up-welling solar fluxes during the AIOP have been compared with the data measured by up- and down-looking solar broadband radiometers aboard a profiling research aircraft. The measured profiles of aerosol extinction, SSA, and water vapor obtained from the same aircraft that carried the radiometers served as the inputs for the model calculations. It is noteworthy that for this study, the uplooking radiometers were mounted on a stabilized platform that kept the radiometers parallel with respect to the earth’s horizontal plane. The results indicate that the shape of the aerosol extinction profiles has very little impact on direct radiative forcings at the top of atmosphere and surface in a cloud-free sky. However, as long as the aerosol is not purely scattering, the shape of the extinction profiles is important for forcing profiles. Identical extinction profiles with different absorption profiles drastically influence the forcing and heating rate profiles. Using aircraft data from 19 AIOP profiles over the Southern Great Plains (SGP), we are able to achieve broadband down-welling solar flux closure within 0.8% (bias difference) or 1.8% (rms difference), well within the expected measurement uncertainty of 1 to 3%. The poorer agreement in up-welling flux (bias -3.7%, rms 10%) is attributed to the use of inaccurate surface albedo data. The sensitivity tests reveal the important role accurate, vertically resolved aerosol extinction data plays in tightening flux closure. This study also suggests that in the presence of a strongly absorbing substance

  14. Effect of heating rate on toxicity of pyrolysis gases from some elastomers

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Kosola, K. L.; Solis, A. N.

    1977-01-01

    The effect of heating rate on the toxicity of the pyrolysis gases from six elastomers was investigated, using a screening test method. The elastomers were polyisoprene (natural rubber), styrene-butadiene rubber (SBR), ethylene propylene diene terpolymer (EPDM), acrylonitrile rubber, chlorosulfonated polyethylene rubber, and polychloroprene. The rising temperature and fixed temperature programs produced exactly the same rank order of materials based on time to death. Acrylonitrile rubber exhibited the greatest toxicity under these test conditions, and carbon monoxide was not found in sufficient concentrations to be the primary cause of death.

  15. Effect of heating rate on toxicity of pyrolysis gases from some synthetic polymers

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Soriano, J. A.; Kosola, K. L.

    1977-01-01

    The effect of heating rate on the toxicity of the pyrolysis gases from some synthetic polymers was investigate, using a screening test method. The synthetic polymers were polyethylene, polystyrene, polymethyl methacrylate, polycarbonate, ABS, polyaryl sulfone, polyether sulfone, and polyphenylene sulfide. The toxicants from the sulfur-containing polymers appeared to act more rapidly than the toxicants from the other polymers. It is not known whether this effect is due primarily to differences in concentration or in the nature of the toxicants. The carbon monoxide concentrations found do not account for the observed results.

  16. Size-dependant heating rates of iron oxide nanoparticles for magnetic fluid hyperthermia.

    PubMed

    Gonzales-Weimuller, Marcela; Zeisberger, Matthias; Krishnan, Kannan M

    2009-07-01

    Using the thermal decomposition of organometallics method we have synthesized high-quality, iron oxide nanoparticles of tailorable size up to ~15nm and transferred them to a water phase by coating with a biocompatible polymer. The magnetic behavior of these particles was measured and fit to a log-normal distribution using the Chantrell method and their polydispersity was confirmed to be very narrow. By performing calorimetry measurements with these monodisperse particles we have unambiguously demonstrated, for the first time, that at a given frequency, heating rates of superparamagnetic particles are dependent on particle size, in agreement with earlier theoretical predictions.

  17. Advanced Fuel Cycle Initiative - Projected Linear Heat Generation Rate and Burnup Calculations

    SciTech Connect

    Richard G. Ambrosek; Gray S. Chang; Debbie J. Utterbeck

    2005-02-01

    This report provides documentation of the physics analysis performed to determine the linear heat generation rate (LHGR) and burnup calculations for the Advanced Fuel Cycle Initiative (AFCI) tests, AFC-1D, AFC-1H, and AFC-1G. The AFC-1D and AFC-1H tests consists of low-fertile metallic fuel compositions and the AFC-1G test consists of non-fertile and low-fertile nitride compositions. These tests will be irradiated in the East Flux Trap (EFT) positions E1, E2, and E3, respectively, during Advanced Test Reactor (ATR) Cycle 135B.

  18. Unsteady Aerodynamic Interaction between Two Bodies at Hypersonic Speed

    NASA Astrophysics Data System (ADS)

    Ozawa, Hiroshi; Kitamura, Keiichi; Hanai, Katsuhisa; Mori, Koichi; Nakamura, Yoshiaki

    This paper presents experimental results of unsteady aerodynamic interactions including Shock/Shock Interaction (SSI) and Shock/Boundary Layer Interaction (SBLI) between two bodies at hypersonic speed. These interactions can be seen in space vehicles consisting of multi-bodies, such as a TSTO, or at a scramjet engine inlet. The present study considers the effect of a flat plate below the SSI where a boundary-layer is developed on the plate surface. More specifically, the interacted flow for a combination of a flat plate (FP) and a hemi-circular cylinder (HCC) is examined at a hypersonic speed (M∞=8.1) the distributions of surface pressure and heat transfer rate are measured. To obtain various SSI patterns, the clearance between two bodies (FP and HCC) is changed. Results show that unsteadiness at the SSI point causes a feedback loop between the two bodies; a jet flow impinges on the FP, the effect of which propagates upstream where the jet impinges on the FP, and the aerodynamic and aerothermodynamic loads reach their maxima. Finally, we found that the feedback loop can be destroyed by installing a fence on the FP to reduce unsteadiness of flow field.

  19. Change in heat capacity for enzyme catalysis determines temperature dependence of enzyme catalyzed rates.

    PubMed

    Hobbs, Joanne K; Jiao, Wanting; Easter, Ashley D; Parker, Emily J; Schipper, Louis A; Arcus, Vickery L

    2013-11-15

    The increase in enzymatic rates with temperature up to an optimum temperature (Topt) is widely attributed to classical Arrhenius behavior, with the decrease in enzymatic rates above Topt ascribed to protein denaturation and/or aggregation. This account persists despite many investigators noting that denaturation is insufficient to explain the decline in enzymatic rates above Topt. Here we show that it is the change in heat capacity associated with enzyme catalysis (ΔC(‡)p) and its effect on the temperature dependence of ΔG(‡) that determines the temperature dependence of enzyme activity. Through mutagenesis, we demonstrate that the Topt of an enzyme is correlated with ΔC(‡)p and that changes to ΔC(‡)p are sufficient to change Topt without affecting the catalytic rate. Furthermore, using X-ray crystallography and molecular dynamics simulations we reveal the molecular details underpinning these changes in ΔC(‡)p. The influence of ΔC(‡)p on enzymatic rates has implications for the temperature dependence of biological rates from enzymes to ecosystems.

  20. The influence of heating rate on superconducting characteristics of MgB2 obtained by spark plasma sintering technique

    NASA Astrophysics Data System (ADS)

    Aldica, G.; Burdusel, M.; Popa, S.; Enculescu, M.; Pasuk, I.; Badica, P.

    2015-12-01

    Superconducting bulks of MgB2 were obtained by the Spark Plasma Sintering (SPS) technique. Different heating rates of 20, 100, 235, 355, and 475 °C/min were used. Samples have high density, above 95%. The onset critical temperature Tc, is about 38.8 K. There is an optimum heating rate of ∼100 °C/min to maximize the critical current density Jc0, the irreversibility field Hirr, the product (Jc0 x μ0Hirr), and to partially avoid formation of undesirable flux jumps at low temperatures. Significant microstructure differences were revealed for samples processed with low and high heating rates in respect to grain boundaries.

  1. NOTE: Effects of mass flow rate and droplet velocity on surface heat flux during cryogen spray cooling

    NASA Astrophysics Data System (ADS)

    Karapetian, Emil; Aguilar, Guillermo; Kimel, Sol; Lavernia, Enrique J.; Nelson, J. Stuart

    2003-01-01

    Cryogen spray cooling (CSC) is used to protect the epidermis during dermatologic laser surgery. To date, the relative influence of the fundamental spray parameters on surface cooling remains incompletely understood. This study explores the effects of mass flow rate and average droplet velocity on the surface heat flux during CSC. It is shown that the effect of mass flow rate on the surface heat flux is much more important compared to that of droplet velocity. However, for fully atomized sprays with small flow rates, droplet velocity can make a substantial difference in the surface heat flux.

  2. Low effective activation energies for oxygen release from metal oxides: evidence for mass-transfer limits at high heating rates.

    PubMed

    Jian, Guoqiang; Zhou, Lei; Piekiel, Nicholas W; Zachariah, Michael R

    2014-06-06

    Oxygen release from metal oxides at high temperatures is relevant to many thermally activated chemical processes, including chemical-looping combustion, solar thermochemical cycles and energetic thermite reactions. In this study, we evaluated the thermal decomposition of nanosized metal oxides under rapid heating (~10(5) K s(-1)) with time-resolved mass spectrometry. We found that the effective activation-energy values that were obtained using the Flynn-Wall-Ozawa isoconversional method are much lower than the values found at low heating rates, indicating that oxygen transport might be rate-determining at a high heating rate.

  3. Impact of computers on aerodynamics research and development

    NASA Technical Reports Server (NTRS)

    Peterson, V. L.

    1984-01-01

    Factors motivating the development of computational aerodynamics as a discipline are traced back to the limitations of the tools available to the aerodynamicist before the development of digital computers. Governing equations in exact and approximate forms are discussed together with approaches to their numerical solution. Example results obtained from the successively refined forms of the equations are presented and discussed, both in the context of levels of computer power required and the degree of the effect that their solution has on aerodynamic research and development. Factors pacing advances in computational aerodynamics are identified, including the amount of computational power required to take the next major step in the discipline. Finally, the Numerical Aerodynamic Simulation (NAS) Program - with its 1987 target of achieving a sustained computational rate of 1 billion floating-point operations per second operating on a memory of 240 million words - is briefly discussed in terms of its projected effect on the future of computational aerodynamics.

  4. A flight experiment to measure rarefied-flow aerodynamics

    NASA Technical Reports Server (NTRS)

    Blanchard, Robert C.

    1990-01-01

    A flight experiment to measure rarefied-flow aerodynamics of a blunt lifting body is being developed by NASA. This experiment, called the Rarefied-Flow Aerodynamic Measurement Experiment (RAME), is part of the Aeroassist Flight Experiment (AFE) mission, which is a Pathfinder design tool for aeroassisted orbital transfer vehicles. The RAME will use flight measurements from accelerometers, rate gyros, and pressure transducers, combined with knowledge of AFE in-flight mass properties and trajectory, to infer aerodynamic forces and moments in the rarefied-flow environment, including transition into the hypersonic continuum regime. Preflight estimates of the aerodynamic measurements are based upon environment models, existing computer simulations, and ground test results. Planned maneuvers at several altitudes will provide a first-time opportunity to examine gas-surface accommondation effects on aerodynamic coefficients in an environment of changing atmospheric composition. A description is given of the RAME equipment design.

  5. A flight experiment to measure rarefied-flow aerodynamics

    NASA Technical Reports Server (NTRS)

    Blanchard, Robert C.

    1990-01-01

    A flight experiment to measure rarefied-flow aerodynamics of a blunt lifting body is being developed by NASA. This experiment, called the Rarefied-Flow Aerodynamic Measurement Experiment (RAME), is part of the Aeroassist Flight Experiment (AFE) mission, which is a Pathfinder design tool for aeroassisted orbital transfer vehicles. The RAME will use flight measurements from accelerometers, rate gyros, and pressure transducers, combined with knowledge of AFE in-flight mass properties and trajectory, to infer aerodynamic forces and moments in the rarefied-flow environment, including transition into the hypersonic continuum regime. Preflight estimates of the aerodynamic measurements are based upon environment models, existing computer simulations, and ground test results. Planned maneuvers at several altitudes will provide a first-time opportunity to examine gas-surface accommondation effects on aerodynamic coefficients in an environment of changing atmospheric composition. A description is given of the RAME equipment design.

  6. The anatomy and internal aerodynamics of canine olfaction

    NASA Astrophysics Data System (ADS)

    Craven, Brent; Paterson, Eric; Settles, Gary

    2007-11-01

    High-resolution magnetic resonance imaging (MRI) scans of the nasal airway of a large dog reveal an intricate scrollwork of nasal conchae providing large surface area for heat, moisture, and odorant transfer. From these anatomical scans we reconstruct a 3-D surface model of the nasal passage and extract detailed morphometric data providing insight into the internal airflows of canine olfaction. A complicated airway network is revealed, wherein the branched maxilloturbinate and ethmoturbinate scrolls are structurally distinct. 3-D airway connectivity also reveals separate respiratory and olfactory flow paths. Knowing the approximate airflow rate and frequency of canine sniffing, we find Reynolds numbers that are, surprisingly, well below the turbulent-flow threshold. Finally, the internal aerodynamics and transport phenomena of canine olfaction are considered via non-dimensional analysis and initially-simple theoretical and computational models. (To appear in the Anatomical Record.)

  7. Aerodynamic Analysis of Tektites and Their Parent Bodies

    NASA Technical Reports Server (NTRS)

    Adams, E. W.; Huffaker, R. M.

    1962-01-01

    Experiment and analysis indicate that the button-type australites were derived from glassy spheres which entered or re-entered the atmosphere as cold solid bodies; in case of average-size specimens, the entry direction was nearly horizontal and the entry speed between 6.5 and 11.2 km/sec. Terrestrial origin of such spheres is impossible because of extremely high deceleration rates at low altitudes. The limited extension of the strewn fields rules out extraterrestrial origin of clusters of such spheres because of stability considerations for clusters in space. However, tektites may have been released as liquid droplets from glassy parent bodies ablating in the atmosphere of the earth. The australites then have skipped together with the parent body in order to re-enter as cold spheres. Terrestrial origin of a parent body would require an extremely violent natural event. Ablation analysis shows that fusion of opaque siliceous stone into glass by aerodynamic heating is impossible.

  8. Thermal conductance and basal metabolic rate are part of a coordinated system for heat transfer regulation

    PubMed Central

    Naya, Daniel E.; Spangenberg, Lucía; Naya, Hugo; Bozinovic, Francisco

    2013-01-01

    Thermal conductance measures the ease with which heat leaves or enters  an organism's body. Although the analysis of this physiological variable in relation to climatic and ecological factors can be traced to studies by Scholander and colleagues, only small advances have occurred ever since. Here, we analyse the relationship between minimal thermal conductance estimated during summer (Cmin) and several ecological, climatic and geographical factors for 127 rodent species, in order to identify the exogenous factors that have potentially affected the evolution of thermal conductance. In addition, we evaluate whether there is compensation between Cmin and basal metabolic rate (BMR)—in such a way that a scale-invariant ratio between both variables is equal to one—as could be expected from the Scholander–Irving model of heat transfer. Our major findings are (i) annual mean temperature is the best single predictor of mass-independent Cmin. (ii) After controlling for the effect of body mass, there is a strong positive correlation between log10 (Cmin) and log10 (BMR). Further, the slope of this correlation is close to one, indicating an almost perfect compensation between both physiological variables. (iii) Structural equation modelling indicated that Cmin values are adjusted to BMR values and not the other way around. Thus, our results strongly suggest that BMR and thermal conductance integrate a coordinated system for heat regulation in endothermic animals and that summer conductance values are adjusted (in an evolutionary sense) to track changes in BMRs. PMID:23902915

  9. Effect of nose shape on three-dimensional stagnation region streamlines and heating rates

    NASA Technical Reports Server (NTRS)

    Hassan, Basil; Dejarnette, Fred R.; Zoby, E. V.

    1991-01-01

    A new method for calculating the three-dimensional inviscid surface streamlines and streamline metrics using Cartesian coordinates and time as the independent variable of integration has been developed. The technique calculates the streamline from a specified point on the body to a point near the stagnation point by using a prescribed pressure distribution in the Euler equations. The differential equations, which are singular at the stagnation point, are of the two point boundary value problem type. Laminar heating rates are calculated using the axisymmetric analog concept for three-dimensional boundary layers and approximate solutions to the axisymmetric boundary layer equations. Results for elliptic conic forebody geometries show that location of the point of maximum heating depends on the type of conic in the plane of symmetry and the angle of attack, and that this location is in general different from the stagnation point. The new method was found to give smooth predictions of heat transfer in the nose region where previous methods gave oscillatory results.

  10. Crystallization of isotactic polypropylene from mesomorphic phase: a constant heating rate study

    NASA Astrophysics Data System (ADS)

    Asakawa, H.; Nishida, K.; Matsuba, G.; Kanaya, T.; Ogawa, H.

    2011-01-01

    We have studied crystallization behaviour of isotactic polypropylene (iPP) from mesomorphic phase in structural point of view. Time-resolved wide-angle X-ray diffraction (WAXD) measurements during a heating process have been performed using a synchrotron radiation (SR) X-ray beam line at SPring-8, Japan. The heating process was so programmed to reproduce a thermal trace of differential scanning calorimetry (DSC) with a constant heating rate (10 °C/min) in order to compare the structural change with thermal behaviour. SR-WAXD sensitively detected the crystallization behaviour and we have obtained fractions of alpha-crystal, mesomorphic phase and amorphous phase as a function of temperature by analysing the data. The results showed that the crystallization from mesomorphic phase proceeds in between 60 and 120 °C (meso-alpha transition). During this process, the crystallization from amorphous hardly takes place. The crystalline fraction shows almost constant in between 120 and 140 °C meanwhile, the mesomorphic fraction still decreases above 120 °C. The crystalline fraction starts to decrease above 140 °C and the most extensively decreases at around 165 °C (melting point). We have also determined the energy level of the mesomorphic phase (meta-stable state) relative to that of alpha-crystal (stable state), considering the balance among the fractions of alpha-crystal, mesomorphic phase and amorphous.

  11. The rate of heat storage mediates an anticipatory reduction in exercise intensity during cycling at a fixed rating of perceived exertion.

    PubMed

    Tucker, Ross; Marle, Trevor; Lambert, Estelle V; Noakes, Timothy D

    2006-08-01

    The aim of the present study was to examine the regulation of exercise intensity in hot environments when exercise is performed at a predetermined, fixed subjective rating of perceived exertion (RPE). Eight cyclists performed cycling trials at 15 degrees C (COOL), 25 degrees C (NORM) and 35 degrees C (HOT) (65% humidity throughout), during which they were instructed to cycle at a Borg rating of perceived exertion (RPE) of 16, increasing or decreasing their power output in order to maintain this RPE. Power output declined linearly in all three trials and the rate of decline was significantly higher in HOT than in NORM and COOL (2.35 +/- 0.73 W min(-1), 1.63 +/- 0.70 and 1.61 +/- 0.80 W min(-1), respectively, P < 0.05). The rate of heat storage was significantly higher in HOT for the first 4 min of the trials only, as a result of increasing skin temperatures. Thereafter, no differences in heat storage were found between conditions. We conclude that the regulation of exercise intensity is controlled by an initial afferent feedback regarding the rate of heat storage, which is used to regulate exercise intensity and hence the rate of heat storage for the remainder of the anticipated exercise bout. This regulation maintains thermal homeostasis by reducing the exercise work rate and utilizing the subjective RPE specifically to ensure that excessive heat accumulation does not occur and cellular catastrophe is avoided.

  12. Microstructural evolution during ultra-rapid annealing of severely deformed low-carbon steel: strain, temperature, and heating rate effects

    NASA Astrophysics Data System (ADS)

    Mostafaei, M. A.; Kazeminezhad, M.

    2016-07-01

    An interaction between ferrite recrystallization and austenite transformation in low-carbon steel occurs when recrystallization is delayed until the intercritical temperature range by employing high heating rate. The kinetics of recrystallization and transformation is affected by high heating rate and such an interaction. In this study, different levels of strain are applied to low-carbon steel using a severe plastic deformation method. Then, ultra-rapid annealing is performed at different heating rates of 200-1100°C/s and peak temperatures of near critical temperature. Five regimes are proposed to investigate the effects of heating rate, strain, and temperature on the interaction between recrystallization and transformation. The microstructural evolution of severely deformed low-carbon steel after ultra-rapid annealing is investigated based on the proposed regimes. Regarding the intensity and start temperature of the interaction, different microstructures consisting of ferrite and pearlite/martensite are formed. It is found that when the interaction is strong, the microstructure is refined because of the high kinetics of transformation and recrystallization. Moreover, strain shifts an interaction zone to a relatively higher heating rate. Therefore, severely deformed steel should be heated at relatively higher heating rates for it to undergo a strong interaction.

  13. What Determines the Meridional Heat Transport? Insights from Varying Rotation Rate Experiments

    NASA Astrophysics Data System (ADS)

    Liu, X.; Battisti, D. S.; Roe, G.

    2016-12-01

    The atmosphere-ocean system transports energy polewards, balancing the energy surplus in the tropics and the deficit in the extratropics. We explore the question "what determines the annual mean total meridional heat transport (MHT)?" by performing a set of rotation-rate experiments with an aquaplanet atmospheric General Circulation model (GFDL AM2.1) coupled to a slab ocean. We change the planet's rotation rate (Ω) from 1/8 to four times its present-day value (ΩE). We find that over this range of rotation rates the change of MHT with Ω falls into two regimes: a slow regime (Ω/ΩE< 0.5), in which MHT decreases with increasing Ω, and a fast regime (Ω/ΩE≥0.5), in which MHT is relatively constant. These two regimes of MHT can be understood in terms of difference between the equator-to-pole imbalance of absorbed shortwave radiation (ASR*) and the imbalance of outgoing longwave radiation (OLR*): MHT = ASR* - OLR*. In both regimes, the response is predominantly associated with the narrowing and weakening of the Hadley Cell with increasing Ω. In the slow regime, the narrowing and weakening Hadley cell reduces the heat transport by the mean meridional circulation; the resulted warming causes a local increase in OLR, which consequently increases OLR* and decreases MHT. In the fast regime the continued contraction and weakening of the Hadley Cell is also associated with a decrease in low-level tropical clouds, which increases local ASR by an amount that almost exactly compensates the local increases in OLR. Thus ASR* - OLR* and hence MHT remains approximately constant. The behavior of MHT with Ω is consistent with the change of dynamics with Ω. For the slow regime, the Hadley cell contributes significantly to MHT. The mass transport (and hence the heat transport) by the Hadley Cell decreases with increasing Ω, resulting in a decrease in MHT. In the fast regime, MHT is predominantly accomplished by atmospheric eddies. Both the eddy length scale and the velocity

  14. Experimental constraints on heating and cooling rates of refractory inclusions in the early solar system

    NASA Technical Reports Server (NTRS)

    Boynton, W. V.; DRAKE; HILDEBRAND; JONES; LEWIS; TREIMAN; WARK

    1987-01-01

    The refractory inclusions in carbonaceous chondrites were the subject of considerable interest since their discovery. These inclusions contain minerals that are predicted to be some of the earliest condensates from the solar nebula, and contain a plethora of isotopic anomalies of unknown origin. Of particular interest are those coarse-grained inclusions that contain refractory metal particles (Fe, Ni, Pt, Ru, Os Ir). Experimental studies of these inclusions in terrestrial laboratories are, however, complicated because the dense particles tend to settle out of a molten or partially molten silicate material. Heating experiments in the Space Station technology and microgravity in order to observe the effects of metal nuggets (which may act as heterogeneous nucleation sites) on nucleation rates in silicate systems and to measure simultaneously the relative volatilization rate of siderophile and lithophile species. Neither experiment is possible in the terrestrial environment.

  15. Hypersonic static aerodynamics for Mars science laboratory entry capsule

    NASA Astrophysics Data System (ADS)

    Yang, Xiaofeng; Tang, Wei; Gui, Yewei; Du, Yanxia; Xiao, Guangming; Liu, Lei

    2014-10-01

    The Mars Science Laboratory (MSL) entry capsule has been designed as a lifting entry for sufficient deceleration and precise landing performance. This paper presents the static aerodynamics analysis of the MSL capsule in the hypersonic entry process for exploration mission to Mars. Hypersonic static coefficients were derived from fully three-dimensional computational fluid dynamics solutions with a specified effective specific heat ratio on a typical trajectory state. Aerodynamic performance analysis ascertains the trim characteristics and static stability of the capsule with respect to the center of gravity (CG) location. Analysis results obtained show that CG location determines the trim characteristics and the static stability, and certain CG radial and axial shift alters the lifting entry performance, so that proper aerodynamic configuration and inner equipment layout is needed for CG adjustment to satisfy the static aerodynamics requirements.

  16. Instantaneous Metabolic Cost of Walking: Joint-Space Dynamic Model with Subject-Specific Heat Rate

    PubMed Central

    Roberts, Dustyn; Hillstrom, Howard; Kim, Joo H.

    2016-01-01

    A subject-specific model of instantaneous cost of transport (ICOT) is introduced from the joint-space formulation of metabolic energy expenditure using the laws of thermodynamics and the principles of multibody system dynamics. Work and heat are formulated in generalized coordinates as functions of joint kinematic and dynamic variables. Generalized heat rates mapped from muscle energetics are estimated from experimental walking metabolic data for the whole body, including upper-body and bilateral data synchronization. Identified subject-specific energetic parameters—mass, height, (estimated) maximum oxygen uptake, and (estimated) maximum joint torques—are incorporated into the heat rate, as opposed to the traditional in vitro and subject-invariant muscle parameters. The total model metabolic energy expenditure values are within 5.7 ± 4.6% error of the measured values with strong (R2 > 0.90) inter- and intra-subject correlations. The model reliably predicts the characteristic convexity and magnitudes (0.326–0.348) of the experimental total COT (0.311–0.358) across different subjects and speeds. The ICOT as a function of time provides insights into gait energetic causes and effects (e.g., normalized comparison and sensitivity with respect to walking speed) and phase-specific COT, which are unavailable from conventional metabolic measurements or muscle models. Using the joint-space variables from commonly measured or simulated data, the models enable real-time and phase-specific evaluations of transient or non-periodic general tasks that use a range of (aerobic) energy pathway similar to that of steady-state walking. PMID:28030598

  17. Cloud radiative forcing induced by layered clouds and associated impact on the atmospheric heating rate

    NASA Astrophysics Data System (ADS)

    Lü, Qiaoyi; Li, Jiming; Wang, Tianhe; Huang, Jianping

    2015-10-01

    A quantitative analysis of cloud fraction, cloud radiative forcing, and cloud radiative heating rate (CRH) of the single-layered cloud (SLC) and the multi-layered cloud (MLC), and their differences is presented, based on the 2B-CLDCLASS-LIDAR and 2B-FLXHR-LIDAR products on the global scale. The CRH at a given atmospheric level is defined as the cloudy minus clear-sky radiative heating rate. The statistical results show that the globally averaged cloud fraction of the MLC (24.9%), which is primarily prevalent in equatorial regions, is smaller than that of the SLC (46.6%). The globally averaged net radiative forcings (NET CRFs) induced by the SLC (MLC) at the top and bottom of the atmosphere (TOA and BOA) and in the atmosphere (ATM) are-60.8 (-40.9),-67.5 (-49.6), and 6.6 (8.7) W m-2, respectively, where the MLC contributes approximately 40.2%, 42.4%, and 57% to the NET CRF at the TOA, BOA, and in the ATM, respectively. The MLC exhibits distinct differences to the SLC in terms of CRH. The shortwave CRH of the SLC (MLC) reaches a heating peak at 9.75 (7.5) km, with a value of 0.35 (0.60) K day-1, and the differences between SLC and MLC transform from positive to negative with increasing altitude. However, the longwave CRH of the SLC (MLC) reaches a cooling peak at 2 (8) km, with a value of-0.45 (-0.42) K day-1, and the differences transform from negative to positive with increasing altitude. In general, the NET CRH differences between SLC and MLC are negative below 7.5 km. These results provide an observational basis for the assessment and improvement of the cloud parameterization schemes in global models.

  18. Regional differences in sweat rate response of steers to short-term heat stress.

    PubMed

    Scharf, B; Wax, L E; Aiken, G E; Spiers, D E

    2008-11-01

    Six Angus steers (319 +/- 8.5 kg) were assigned to one of two groups (hot or cold exposure) of three steers each, and placed into two environmental chambers initially maintained at 16.5-18.8 degrees C air temperature (Ta). Cold chamber Ta was lowered to 8.4 degrees C, while Ta within the hot chamber was increased to 32.7 degrees C over a 24-h time period. Measurements included respiration rate, and air and body (rectal and skin) temperatures. Skin temperature was measured at shoulder and rump locations, with determination of sweat rate using a calibrated moisture sensor. Rectal temperature did not change in cold or hot chambers. However, respiration rate nearly doubled in the heat (P < 0.05), increasing when Ta was above 24 degrees C. Skin temperatures at the two locations were highly correlated (P < 0.05) with each other and with Ta. In contrast, sweat rate showed differences at rump and shoulder sites. Sweat rate of the rump exhibited only a small increase with Ta. However, sweat rate at the shoulder increased more than four-fold with increasing Ta. Increased sweat rate in this region is supported by an earlier report of a higher density of sweat glands in the shoulder compared to rump regions. Sweat rate was correlated with several thermal measurements to determine the best predictor. Fourth-order polynomial expressions of short-term rectal and skin temperature responses to hot and cold exposures produced r values of 0.60, 0.84, and 0.98, respectively. These results suggest that thermal inputs other than just rectal or skin temperature drive the sweat response in cattle.

  19. Regional differences in sweat rate response of steers to short-term heat stress

    NASA Astrophysics Data System (ADS)

    Scharf, B.; Wax, L. E.; Aiken, G. E.; Spiers, D. E.

    2008-11-01

    Six Angus steers (319 ± 8.5 kg) were assigned to one of two groups (hot or cold exposure) of three steers each, and placed into two environmental chambers initially maintained at 16.5-18.8°C air temperature ( T a). Cold chamber T a was lowered to 8.4°C, while T a within the hot chamber was increased to 32.7°C over a 24-h time period. Measurements included respiration rate, and air and body (rectal and skin) temperatures. Skin temperature was measured at shoulder and rump locations, with determination of sweat rate using a calibrated moisture sensor. Rectal temperature did not change in cold or hot chambers. However, respiration rate nearly doubled in the heat ( P < 0.05), increasing when T a was above 24°C. Skin temperatures at the two locations were highly correlated ( P < 0.05) with each other and with T a. In contrast, sweat rate showed differences at rump and shoulder sites. Sweat rate of the rump exhibited only a small increase with T a. However, sweat rate at the shoulder increased more than four-fold with increasing T a. Increased sweat rate in this region is supported by an earlier report of a higher density of sweat glands in the shoulder compared to rump regions. Sweat rate was correlated with several thermal measurements to determine the best predictor. Fourth-order polynomial expressions of short-term rectal and skin temperature responses to hot and cold exposures produced r values of 0.60, 0.84, and 0.98, respectively. These results suggest that thermal inputs other than just rectal or skin temperature drive the sweat response in cattle.

  20. Nuclear mass inventory, photon dose rate and thermal decay heat of spent research reactor fuel assemblies

    SciTech Connect

    Pond, R.B.; Matos, J.E.

    1996-12-31

    This document has been prepared to assist research reactor operators possessing spent fuel containing enriched uranium of United States origin to prepare part of the documentation necessary to ship this fuel to the United States. Data are included on the nuclear mass inventory, photon dose rate, and thermal decay heat of spent research reactor fuel assemblies. Isotopic masses of U, Np, Pu and Am that are present in spent research reactor fuel are estimated for MTR, TRIGA and DIDO-type fuel assembly types. The isotopic masses of each fuel assembly type are given as functions of U-235 burnup in the spent fuel, and of initial U-235 enrichment and U-235 mass in the fuel assembly. Photon dose rates of spent MTR, TRIGA and DIDO-type fuel assemblies are estimated for fuel assemblies with up to 80% U-235 burnup and specific power densities between 0.089 and 2.857 MW/kg[sup 235]U, and for fission product decay times of up to 20 years. Thermal decay heat loads are estimated for spent fuel based upon the fuel assembly irradiation history (average assembly power vs. elapsed time) and the spent fuel cooling time.

  1. A simple parameterization of ozone infrared absorption for atmospheric heating rate calculations

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.

    1991-01-01

    A simple parameterization of ozone absorption in the 9.6-micron region which is suitable for two- and three-dimensional stratospheric and tropospheric models is presented. The band is divided into two parts, a brand center region and a band wing region, grouping together regions for which the temperature dependence of absorption is similar. Each of the two regions is modeled with a function having the form of the Goody random model, with pressure and temperature dependent band parameters chosen by empirically fitting line-by-line equivalent widths for pressures between 0.25 and 1000 mbar and ozone absorber amounts between 1.0 x 10 to the -7th and 1.0 cm atm. The model has been applied to calculations of atmospheric heating rates using an absorber amount weighted mean pressure and temperature along the inhomogeneous paths necessary for flux computations. In the stratosphere, maximum errors in the heating rates relative to line-by-line calculations are 0.1 K/d, or 5 percent of the peak cooling at the stratopause. In the troposphere the errors are at most 0.005 K/d.

  2. Broadband Heating Rate Profile Project (BBHRP) - SGP 1bbhrpripbe1mcfarlane

    DOE Data Explorer

    Riihimaki, Laura; Shippert, Timothy

    2014-11-05

    The objective of the ARM Broadband Heating Rate Profile (BBHRP) Project is to provide a structure for the comprehensive assessment of our ability to model atmospheric radiative transfer for all conditions. Required inputs to BBHRP include surface albedo and profiles of atmospheric state (temperature, humidity), gas concentrations, aerosol properties, and cloud properties. In the past year, the Radiatively Important Parameters Best Estimate (RIPBE) VAP was developed to combine all of the input properties needed for BBHRP into a single gridded input file. Additionally, an interface between the RIPBE input file and the RRTM was developed using the new ARM integrated software development environment (ISDE) and effort was put into developing quality control (qc) flags and provenance information on the BBHRP output files so that analysis of the output would be more straightforward. This new version of BBHRP, sgp1bbhrpripbeC1.c1, uses the RIPBE files as input to RRTM, and calculates broadband SW and LW fluxes and heating rates at 1-min resolution using the independent column approximation. The vertical resolution is 45 m in the lower and middle troposphere to match the input cloud properties, but is at coarser resolution in the upper atmosphere. Unlike previous versions, the vertical grid is the same for both clear-sky and cloudy-sky calculations.

  3. Heat rate improvement at Sunflower Electric`s Holcomb Station - a programmatic approach

    SciTech Connect

    Linville, C.; Nelson, K.E.; DesJardins, R.R.

    1996-05-01

    This paper describes the heat rate improvement program implemented at Sunflower Electric Power Corporations Holcomb Generating Station located in Holcomb, Kansas. The Holcomb Station is a large coal-fired generating plant that supplies electricity to Southwestern. Kansas and surrounding states. In 1993, Sunflower Electric (SEPC) established a continuing heat rate improvement program at the Holcomb Station which consisted of a periodic performance test program in combination with continuous on-line monitoring. This paper provides an overview of the test program and initial results and describes a unique approach to monitoring boiler feed pump performance especially suitable for on-line monitoring. implementation of a 15-user LAN-based on-line performance monitoring system is also described. In addition to technical issues, the paper addresses some of the {open_quotes}human factors{close_quotes} encountered while promoting acceptance and use of the on-line monitoring system by all levels of plant personnel. The importance of proper program planning and long term management support is stressed.

  4. Broadband Heating Rate Profile Project (BBHRP) - SGP 1bbhrpripbe1mcfarlane

    DOE Data Explorer

    Riihimaki, Laura; Shippert, Timothy

    2014-11-05

    The objective of the ARM Broadband Heating Rate Profile (BBHRP) Project is to provide a structure for the comprehensive assessment of our ability to model atmospheric radiative transfer for all conditions. Required inputs to BBHRP include surface albedo and profiles of atmospheric state (temperature, humidity), gas concentrations, aerosol properties, and cloud properties. In the past year, the Radiatively Important Parameters Best Estimate (RIPBE) VAP was developed to combine all of the input properties needed for BBHRP into a single gridded input file. Additionally, an interface between the RIPBE input file and the RRTM was developed using the new ARM integrated software development environment (ISDE) and effort was put into developing quality control (qc) flags and provenance information on the BBHRP output files so that analysis of the output would be more straightforward. This new version of BBHRP, sgp1bbhrpripbeC1.c1, uses the RIPBE files as input to RRTM, and calculates broadband SW and LW fluxes and heating rates at 1-min resolution using the independent column approximation. The vertical resolution is 45 m in the lower and middle troposphere to match the input cloud properties, but is at coarser resolution in the upper atmosphere. Unlike previous versions, the vertical grid is the same for both clear-sky and cloudy-sky calculations.

  5. Mathematical model of cycad cones' thermogenic temperature responses: inverse calorimetry to estimate metabolic heating rates.

    PubMed

    Roemer, R B; Booth, D; Bhavsar, A A; Walter, G H; Terry, L I

    2012-12-21

    A mathematical model based on conservation of energy has been developed and used to simulate the temperature responses of cones of the Australian cycads Macrozamia lucida and Macrozamia. macleayi during their daily thermogenic cycle. These cones generate diel midday thermogenic temperature increases as large as 12 °C above ambient during their approximately two week pollination period. The cone temperature response model is shown to accurately predict the cones' temperatures over multiple days as based on simulations of experimental results from 28 thermogenic events from 3 different cones, each simulated for either 9 or 10 sequential days. The verified model is then used as the foundation of a new, parameter estimation based technique (termed inverse calorimetry) that estimates the cones' daily metabolic heating rates from temperature measurements alone. The inverse calorimetry technique's predictions of the major features of the cones' thermogenic metabolism compare favorably with the estimates from conventional respirometry (indirect calorimetry). Because the new technique uses only temperature measurements, and does not require measurements of oxygen consumption, it provides a simple, inexpensive and portable complement to conventional respirometry for estimating metabolic heating rates. It thus provides an additional tool to facilitate field and laboratory investigations of the bio-physics of thermogenic plants.

  6. High temperature gasification of high heating-rate chars using a flat-flame reactor

    DOE PAGES

    Li, Tian; Niu, Yanqing; Wang, Liang; ...

    2017-08-25

    The increasing interest in gasification and oxy-fuel combustion of biomass has heightened the need for a detailed understanding of char gasification in industrially relevant environments (i.e., high temperature and high-heating rate). Despite innumerable studies previously conducted on gasification of biomass, very few have focused on such conditions. Consequently, in this study the high-temperature gasification behaviors of biomass-derived chars were investigated using non-intrusive techniques. Two biomass chars produced at a heating rate of approximately 104 K/s were subjected to two gasification environments and one oxidation environment in an entrained flow reactor equipped with an optical particle-sizing pyrometer. A coal char producedmore » from a common U.S. low sulfur subbituminous coal was also studied for comparison. Both char and surrounding gas temperatures were precisely measured along the centerline of the furnace. Despite differences in the physical and chemical properties of the biomass chars, they exhibited rather similar reaction temperatures under all investigated conditions. On the other hand, a slightly lower particle temperature was observed in the case of coal char gasification, suggesting a higher gasification reactivity for the coal char. A comprehensive numerical model was applied to aid the understanding of the conversion of the investigated chars under gasification atmospheres. In addition, a sensitivity analysis was performed on the influence of four parameters (gas temperature, char diameter, char density, and steam concentration) on the carbon conversion rate. Here, the results demonstrate that the gas temperature is the most important single variable influencing the gasification rate.« less

  7. Identification of aerodynamic models for maneuvering aircraft

    NASA Technical Reports Server (NTRS)

    Chin, Suei; Lan, C. Edward

    1990-01-01

    Due to the requirement of increased performance and maneuverability, the flight envelope of a modern fighter is frequently extended to the high angle-of-attack regime. Vehicles maneuvering in this regime are subjected to nonlinear aerodynamic loads. The nonlinearities are due mainly to three-dimensional separated flow and concentrated vortex flow that occur at large angles of attack. Accurate prediction of these nonlinear airloads is of great importance in the analysis of a vehicle's flight motion and in the design of its flight control system. A satisfactory evaluation of the performance envelope of the aircraft may require a large number of coupled computations, one for each change in initial conditions. To avoid the disadvantage of solving the coupled flow-field equations and aircraft's motion equations, an alternate approach is to use a mathematical modeling to describe the steady and unsteady aerodynamics for the aircraft equations of motion. Aerodynamic forces and moments acting on a rapidly maneuvering aircraft are, in general, nonlinear functions of motion variables, their time rate of change, and the history of maneuvering. A numerical method was developed to analyze the nonlinear and time-dependent aerodynamic response to establish the generalized indicial function in terms of motion variables and their time rates of change.

  8. Analysis of read-out heating rate effects on the glow peaks of TLD-100 using WinGCF software

    SciTech Connect

    Bauk, Sabar; Hussin, Siti Fatimah; Alam, Md. Shah

    2016-01-22

    This study was done to analyze the effects of the read-out heating rate on the LiF:Mg,Ti (TLD-100) thermoluminescent dosimeters (TLD) glow peaks using WinGCF computer software. The TLDs were exposed to X-ray photons with a potential difference of 72 kVp and 200 mAs in air and were read-out using a Harshaw 3500 TLD reader. The TLDs were read-out using four read-out heating rates at 10, 7, 4 and 1 °C s{sup −1}. It was observed that lowering the heating rate could separate more glow peaks. The activation energy for peak 5 was found to be lower than that for peak 4. The peak maximum temperature and the integral value of the main peak decreased as the heating rate decreases.

  9. Investigations on the heat transport capability of a cryogenic oscillating heat pipe and its application in achieving ultra-fast cooling rates for cell vitrification cryopreservation☆

    PubMed Central

    Han, Xu; Ma, Hongbin; Jiao, Anjun; Critser, John K.

    2010-01-01

    Theoretically, direct vitrification of cell suspensions with relatively low concentrations (~1 M) of permeating cryoprotective agents (CPA) is suitable for cryopreservation of almost all cell types and can be accomplished by ultra-fast cooling rates that are on the order of 106–7 K/min. However, the methods and devices currently available for cell cryopreservation cannot achieve such high cooling rates. In this study, we constructed a novel cryogenic oscillating heat pipe (COHP) using liquid nitrogen as its working fluid and investigated its heat transport capability to assess its application for achieving ultra-fast cooling rates for cell cryopreservation. The experimental results showed that the apparent heat transfer coefficient of the COHP can reach 2 × 105 W/m2·K, which is two orders of the magnitude higher than traditional heat pipes. Theoretical analyzes showed that the average local heat transfer coefficient in the thin film evaporation region of the COHP can reach 1.2 × 106 W/m2·K, which is approximately 103 times higher than that achievable with standard pool-boiling approaches. Based on these results, a novel device design applying the COHP and microfabrication techniques is proposed and its efficiency for cell vitrification is demonstrated through numerical simulation. The estimated average cooling rates achieved through this approach is 106–7 K/min, which is much faster than the currently available methods and sufficient for achieving vitrification with relatively low concentrations of CPA. PMID:18430413

  10. Investigations on the heat transport capability of a cryogenic oscillating heat pipe and its application in achieving ultra-fast cooling rates for cell vitrification cryopreservation.

    PubMed

    Han, Xu; Ma, Hongbin; Jiao, Anjun; Critser, John K

    2008-06-01

    Theoretically, direct vitrification of cell suspensions with relatively low concentrations ( approximately 1 M) of permeating cryoprotective agents (CPA) is suitable for cryopreservation of almost all cell types and can be accomplished by ultra-fast cooling rates that are on the order of 10(6-7) K/min. However, the methods and devices currently available for cell cryopreservation cannot achieve such high cooling rates. In this study, we constructed a novel cryogenic oscillating heat pipe (COHP) using liquid nitrogen as its working fluid and investigated its heat transport capability to assess its application for achieving ultra-fast cooling rates for cell cryopreservation. The experimental results showed that the apparent heat transfer coefficient of the COHP can reach 2 x 10(5) W/m(2).K, which is two orders of the magnitude higher than traditional heat pipes. Theoretical analyzes showed that the average local heat transfer coefficient in the thin film evaporation region of the COHP can reach 1.2 x 10(6) W/m(2).K, which is approximately 10(3) times higher than that achievable with standard pool-boiling approaches. Based on these results, a novel device design applying the COHP and microfabrication techniques is proposed and its efficiency for cell vitrification is demonstrated through numerical simulation. The estimated average cooling rates achieved through this approach is 10(6-7)K/min, which is much faster than the currently available methods and sufficient for achieving vitrification with relatively low concentrations of CPA.

  11. CFD research, parallel computation and aerodynamic optimization

    NASA Technical Reports Server (NTRS)

    Ryan, James S.

    1995-01-01

    Over five years of research in Computational Fluid Dynamics and its applications are covered in this report. Using CFD as an established tool, aerodynamic optimization on parallel architectures is explored. The objective of this work is to provide better tools to vehicle designers. Submarine design requires accurate force and moment calculations in flow with thick boundary layers and large separated vortices. Low noise production is critical, so flow into the propulsor region must be predicted accurately. The High Speed Civil Transport (HSCT) has been the subject of recent work. This vehicle is to be a passenger vehicle with the capability of cutting overseas flight times by more than half. A successful design must surpass the performance of comparable planes. Fuel economy, other operational costs, environmental impact, and range must all be improved substantially. For all these reasons, improved design tools are required, and these tools must eventually integrate optimization, external aerodynamics, propulsion, structures, heat transfer and other disciplines.

  12. Aerodynamic Leidenfrost effect

    NASA Astrophysics Data System (ADS)

    Gauthier, Anaïs; Bird, James C.; Clanet, Christophe; Quéré, David

    2016-12-01

    When deposited on a plate moving quickly enough, any liquid can levitate as it does when it is volatile on a very hot solid (Leidenfrost effect). In the aerodynamic Leidenfrost situation, air gets inserted between the liquid and the moving solid, a situation that we analyze. We observe two types of entrainment. (i) The thickness of the air gap is found to increase with the plate speed, which is interpreted in the Landau-Levich-Derjaguin frame: Air is dynamically dragged along the surface and its thickness results from a balance between capillary and viscous effects. (ii) Air set in motion by the plate exerts a force on the levitating liquid. We discuss the magnitude of this aerodynamic force and show that it can be exploited to control the liquid and even to drive it against gravity.

  13. Rarefied-flow aerodynamics

    NASA Technical Reports Server (NTRS)

    Potter, J. Leith

    1992-01-01

    Means for relatively simple and quick procedures are examined for estimating aerodynamic coefficients of lifting reentry vehicles. The methods developed allow aerospace designers not only to evaluate the aerodynamics of specific shapes but also to optimize shapes under given constraints. The analysis was also studied of the effect of thermomolecular flow on pressures measured by an orifice near the nose of a Space Shuttle Orbiter at altitudes above 75 km. It was shown that pressures corrected for thermomolecular flow effect are in good agreement with values predicted by independent theoretical methods. An incidental product was the insight gained about the free molecular thermal accommodation coefficient applicable under 'real' conditions of high speed flow in the Earth's atmosphere. The results are presented as abstracts of referenced papers. One reference paper is presented in its entirety.

  14. HYSHOT-2 Aerodynamics

    NASA Astrophysics Data System (ADS)

    Cain, T.; Owen, R.; Walton, C.

    2005-02-01

    The scramjet flight test Hyshot-2, flew on the 30 July 2002. The programme, led by the University of Queensland, had the primary objective of obtaining supersonic combustion data in flight for comparison with measurements made in shock tunnels. QinetiQ was one of the sponsors, and also provided aerodynamic data and trajectory predictions for the ballistic re-entry of the spinning sounding rocket. The unconventional missile geometry created by the nose-mounted asymmetric-scramjet in conjunction with the high angle of attack during re-entry makes the problem interesting. This paper presents the wind tunnel measurements and aerodynamic calculations used as input for the trajectory prediction. Indirect comparison is made with data obtained in the Hyshot-2 flight using a 6 degree-of-freedom trajectory simulation.

  15. Advanced Aerodynamic Control Effectors

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.; Bauer, Steven X. S.

    1999-01-01

    A 1990 research program that focused on the development of advanced aerodynamic control effectors (AACE) for military aircraft has been reviewed and summarized. Data are presented for advanced planform, flow control, and surface contouring technologies. The data show significant increases in lift, reductions in drag, and increased control power, compared to typical aerodynamic designs. The results presented also highlighted the importance of planform selection in the design of a control effector suite. Planform data showed that dramatic increases in lift (greater than 25%) can be achieved with multiple wings and a sawtooth forebody. Passive porosity and micro drag generator control effector data showed control power levels exceeding that available from typical effectors (moving surfaces). Application of an advanced planform to a tailless concept showed benefits of similar magnitude as those observed in the generic studies.

  16. The Dependence of Atmospheric Circulation and Heat Transport on the Planetary Rotation Rate

    NASA Astrophysics Data System (ADS)

    Basu, S.; Richardson, M. I.; Wilson, R. J.

    2002-12-01

    Simplified models of planetary climate require a parameterization for the equator-to-pole transport of heat and its dependence on factors, including the planetary rotation rate. Various such parameterizations exist, including ones based on the theory of baroclinic eddy mixing, and on principles of global entropy generation. However, such parameterizations are difficult to test given the limited available observational opportunities. In this study, we use a numerical model to examine heat flux dependencies, as part of a wider study of circulation regime sensitivity to rotation rates and other parameters. This study makes use of a simplified version of the Geophysical Fluid Dynamics Laboratory (GFDL) "Skyhi" General Circulation Model (GCM). All terrestrial hydrological processes have been stripped from the model, which in the form used here, is adapted from the Martian version of Skyhi. The atmosphere has the gas properties of CO2, except that it has been made uncondensible. No aerosols or surface ices are allowed. The model surface is flat, and of uniform albedo and thermal inertia. For the simulations presented in this study, the diurnal, seasonal, and eccentricity cycles have been disabled ({ i.e.} the surface and atmosphere receives constant, daily- and seasonally-averaged incident solar radiation). Radiative heating is treated with a band model for CO2 gas in the thermal and near-infrared bands. The use of a complex model to examine simplified theory of heat transport requires some justification since it is not necessarily clear that these models (GCM's) provide an accurate emulation of the real atmosphere (of any given planet). In this study, we have intentionally removed those aspects of GCM's that are of greatest concern. Especially for terrestrial GCM's, the hydrologic cycle is a major source of uncertainty due to radiative feedbacks, and cloud coupling to small-scale, convective mixing. For other planets, aerosols are important as radiatively and dynamical

  17. Aerodynamic noise sources

    NASA Astrophysics Data System (ADS)

    Munin, A. G.; Kuznetsov, V. M.; Leontev, E. A.

    A general theory is developed for aerodynamic sound generation and its propagation in an inhomogeneous medium. Results of theoretical and experimental studies of the acoustic characteristics of jets are discussed, and a solution is presented to the problem concerning the noise from a section, free rotor, and a rotor located inside a channel. Sound propagation in a channel with flow and selection of soundproofing liners for the channel walls are also discussed.

  18. Aerodynamics: The Wright Way

    NASA Technical Reports Server (NTRS)

    Cole, Jennifer Hansen

    2010-01-01

    This slide presentation reviews some of the basic principles of aerodynamics. Included in the presentation are: a few demonstrations of the principles, an explanation of the concepts of lift, drag, thrust and weight, a description of Bernoulli's principle, the concept of the airfoil (i.e., the shape of the wing) and how that effects lift, and the method of controlling an aircraft by manipulating the four forces using control surfaces.

  19. The effect of temperature and heating rate on char properties obtained from solar pyrolysis of beech wood.

    PubMed

    Zeng, Kuo; Minh, Doan Pham; Gauthier, Daniel; Weiss-Hortala, Elsa; Nzihou, Ange; Flamant, Gilles

    2015-04-01

    Char samples were produced from pyrolysis in a lab-scale solar reactor. The pyrolysis of beech wood was carried out at temperatures ranging from 600 to 2000°C, with heating rates from 5 to 450°C/s. CHNS, scanning electron microscopy analysis, X-ray diffractometry, Brunauer-Emmett-Teller adsorption were employed to investigate the effect of temperature and heating rate on char composition and structure. The results indicated that char structure was more and more ordered with temperature increase and heating rate decrease (higher than 50°C/s). The surface area and pore volume firstly increased with temperature and reached maximum at 1200°C then reduced significantly at 2000°C. Besides, they firstly increased with heating rate and then decreased slightly at heating rate of 450°C/s when final temperature was no lower than 1200°C. Char reactivity measured by TGA analysis was found to correlate with the evolution of char surface area and pore volume with temperature and heating rate.

  20. Effect of Cooling Rate on Microstructure and Mechanical Properties of Eutectoid Steel Under Cyclic Heat Treatment

    NASA Astrophysics Data System (ADS)

    Maji, Soma; Subhani, Amir Raza; Show, Bijay Kumar; Maity, Joydeep

    2017-07-01

    A systematic study has been carried out to ascertain the effect of cooling rate on structure and mechanical properties of eutectoid steel subjected to a novel incomplete austenitization-based cyclic heat treatment process up to 4 cycles. Each cycle consists of a short-duration holding (6 min) at 775 °C (above A1) followed by cooling at different rates (furnace cooling, forced air cooling and ice-brine quenching). Microstructure and properties are found to be strongly dependent on cooling rate. In pearlitic transformation regime, lamellar disintegration completes in 61 h and 48 min for cyclic furnace cooling. This leads to a spheroidized structure possessing a lower hardness and strength than that obtained in as-received annealed condition. On contrary, lamellar disintegration does not occur for cyclic forced air cooling with high air flow rate (78 m3 h-1). Rather, a novel microstructure consisting of submicroscopic cementite particles in a `interweaved pearlite' matrix is developed after 4 cycles. This provides an enhancement in hardness (395 HV), yield strength (473 MPa) and UTS (830 MPa) along with retention of a reasonable ductility (%Elongation = 19) as compared to as-received annealed condition (hardness = 222 HV, YS = 358 MPa, UTS = 740 MPa, %Elongation = 21).

  1. Computational and theoretical investigation of Mars's atmospheric impact on the descent module "Exomars-2018" under aerodynamic deceleration

    NASA Astrophysics Data System (ADS)

    Golomazov, M. M.; Ivankov, A. A.

    2016-12-01

    Methods for calculating the aerodynamic impact of the Martian atmosphere on the descent module "Exomars-2018" intended for solving the problem of heat protection of the descent module during aerodynamic deceleration are presented. The results of the investigation are also given. The flow field and radiative and convective heat exchange are calculated along the trajectory of the descent module until parachute system activation.

  2. Comparing the effectiveness of heat rate improvements in different coal-fired power plants utilizing carbon dioxide capture

    NASA Astrophysics Data System (ADS)

    Walsh, Martin Jeremy

    New Congressional legislation may soon require coal-fired power generators to pay for their CO2 emissions and capture a minimum level of their CO2 output. Aminebased CO2 capture systems offer plants the most technically proven and commercially feasible option for CO2 capture at this time. However, these systems require a large amount of heat and power to operate. As a result, amine-based CO2 capture systems significantly reduce the net power of any units in which they are installed. The Energy Research Center has compiled a list of heat rate improvements that plant operators may implement before installing a CO2 capture system. The goal of these improvements is to upgrade the performance of existing units and partially offset the negative effects of adding a CO2 capture system. Analyses were performed in Aspen Plus to determine the effectiveness of these heat rate improvements in preserving the net power and net unit heat rate (NUHR) of four different power generator units. For the units firing high-moisture sub-bituminous coal, the heat rate improvements reduced NUHR by an average of 13.69% across a CO 2 capture level range of 50% to 90%. For the units firing bituminous coal across the same CO2 capture range, the heat rate improvements reduced NUHR by an average of 12.30%. Regardless of the units' coal or steam turbine cycle type, the heat rate improvements preserved 9.7% to 11.0% of each unit's net power across the same CO2 capture range. In general, the heat rate improvements were found to be most effective in improving the performance of units firing high-moisture sub-bituminous. The effect of the CO2 capture system on these units and the reasons for the improvements' greater effectiveness in them are described in this thesis.

  3. Oceanic heat, carbon uptake and enhanced Atlantic sea level rise under high carbon emission rates

    NASA Astrophysics Data System (ADS)

    Krasting, J. P.; Dunne, J. P.; Hallberg, R.; Stouffer, R. J.

    2016-12-01

    Thermal expansion of the ocean in response to anthropogenic climate warming is an important component of historical sea-level rise. Unlike global surface air temperature and other closely related climate variables that are nearly proportional to cumulative carbon emissions, the relationship between global sea level rise and cumulative emissions is less certain. The magnitude of sea level rise resulting from past carbon emissions depends on the integrated amount of warming and the time scales on which that warming occurs. Here, we present results from the GFDL-ESM2G model forced with range of idealized carbon emission rates - ranging from 2 to 25 Gt C yr-1 - that highlight the relationships between cumulative carbon emissions and heat and carbon uptake. Here we show that the Atlantic basin average sea level rise is larger than the Pacific on centennial time scales under present-day rates of carbon emissions and higher. This asymmetry relates to the shorter flushing time scales of the Atlantic and weakening of the Atlantic Meridional Overturning Circulation (AMOC). For a given level of cumulative emissions, we also find that sea-level rise is largest at low emission rates and is related to the long time scales of climate response associated with lower emission rates. While sea level rise is not proportional to cumulative emissions, our results do show, however, that there is a robust relationship between cumulative emissions and upper ocean (0-700m) Atlantic-minus-Pacific temperature differences across the range of emission rates tested with the model. In addition to local subsidence, changes in offshore winds, and ocean dynamical changes, we conclude that present-day high greenhouse gas emission rates make Atlantic coastal areas more vulnerable to sea-level rise over the coming decades. These results give further evidence that single global average measures become less representative of regional scale changes in sea level rise.

  4. New blow-up rates for fast controls of Schrödinger and heat equations

    NASA Astrophysics Data System (ADS)

    Tenenbaum, G.; Tucsnak, M.

    We consider the null-controllability problem for the Schrödinger and heat equations with boundary control. We concentrate on short-time, or fast, controls. We improve recent estimates (see [L. Miller, Geometric bounds on the growth rate of null-controllability cost for the heat equation in small time, J. Differential Equations 204 (2004) 202-226; L. Miller, How violent are fast controls for Schrödinger and plate vibrations?, Arch. Ration. Mech. Anal. 172 (2004) 429-456; L. Miller, Controllability cost of conservative systems: Resolvent condition and transmutation, J. Funct. Anal. 218 (2005) 425-444; L. Miller, The control transmutation method and the cost of fast controls, SIAM J. Control Optim. 45 (2006) 762-772]) on the norm of the operator associating to any initial state the minimal norm control driving the system to zero. Our main results concern the Schrödinger and heat equations in one space dimension. They yield new estimates concerning window problems for series of exponentials as described in [T.I. Seidman, The coefficient map for certain exponential sums, Nederl. Akad. Wetensch. Indag. Math. 48 (1986) 463-478] and in [T.I. Seidman, S.A. Avdonin, S.A. Ivanov, The "window problem" for series of complex exponentials, J. Fourier Anal. Appl. 6 (2000) 233-254]. These results are used, following [L. Miller, The control transmutation method and the cost of fast controls, SIAM J. Control Optim. 45 (2006) 762-772], to deal with the case of several space dimensions.

  5. Alexithymia and fear of pain independently predict heat pain intensity ratings among undergraduate university students.

    PubMed

    Katz, Joel; Martin, Andrea L; Pagé, M Gabrielle; Calleri, Vincent

    2009-01-01

    Alexithymia is a disturbance in awareness and cognitive processing of affect that is associated with over-reporting of physical symptoms, including pain. The relationship between alexithymia and other psychological constructs that are often associated with pain has yet to be evaluated. The present study examined the importance of alexithymia in the pain experience in relation to other integral psychological components of Turk's diathesis-stress model of chronic pain and disability, including fear of pain, anxiety sensitivity, pain avoidance and pain catastrophizing. Heat pain stimuli, using a magnitude estimation procedure, and five questionnaires (Anxiety Sensitivity Index, Fear of Pain Questionnaire III, Pain Catastrophizing Scale, avoidance subscale of the Pain Anxiety Symptoms Scale-20 and Toronto Alexithymia Scale-20) were administered to 67 undergraduate students (44 women) with a mean (+/- SD) age of 20.39+/-3.77 years. Multiple linear regression analysis revealed that sex, fear of pain and alexithymia were the only significant predictors of average heat pain intensity (F[6, 60]=5.43; R2=0.35; P=0.008), accounting for 6.8%, 20.0% and 9.6% of unique variance, respectively. Moreover, the difficulty identifying feelings and difficulty describing feelings subscales, but not the externally oriented thinking subscale of the Toronto Alexithymia Scale-20 significantly predicted average heat pain intensity. Individuals with higher levels of alexithymia or increased fear of pain reported higher average pain intensity ratings. The relationship between alexithymia and pain intensity was unrelated to other psychological constructs usually associated with pain. These findings suggest that difficulties with emotion regulation, either through reduced emotional awareness via alexithymia or heightened emotional awareness via fear of pain, may negatively impact the pain experience.

  6. Investigating Cooling Rates of a Controlled Lava Flow using Infrared Imaging and Three Heat Diffusion Models

    NASA Astrophysics Data System (ADS)

    Tarlow, S.; Lev, E.; Zappa, C. J.; Karson, J.; Wysocki, B.

    2011-12-01

    Observation and investigation of surface cooling rates of active lava flows can help constrain thermal parameters necessary for creating of more precise lava flow models. To understand how the lava cools, temperature data was collected using an infrared video camera. We explored three models of the release of heat from lava stream; one based on heat conduction, another based on crust thickness and radiation, and a third model based on radiative cooling and variable crust thickness. The lava flow, part of the Syracuse University Lava Project (http://lavaproject.syr.edu), was made by pouring molten basalt at 1300 Celsius from a furnace into a narrow trench of sand. Hanging roughly 2 m over the trench, the infrared camera, records the lava's surface temperature for the duration of the flow. We determine the average surface temperature of the lava flow at a fixed location downstream as the mean of the lateral cross section of each frame of the IR imagery. From the recorded IR frames, we calculate the mean cross-channel temperature for each downstream distance. We then examine how this mean temperature evolves over time, and plot cooling curves for selected down-stream positions. We then compared the observed cooling behavior to that predicted by three cooling models: a conductive cooling model, a radiative cooling model with constant crust thickness, and a radiative cooling model with variable crust thickness. All three models are solutions to the one-dimensional heat equation. To create the best fit for the conductive model, we constrained thermal diffusivity and to create the best fit for the radiative model, we constrained crust thickness. From the comparison of our data to the models we can conclude that the lava flow's cooling is primarily driven by radiation.

  7. The effects of pre-oxidation heating rate on bio-based carbon fibers and its surface repair

    NASA Astrophysics Data System (ADS)

    Wu, H.; Cheng, L. F.; Fan, S. W.; Yuan, X. W.; Bhattacharyya, D.

    2015-03-01

    Low-cost carbon fibers (CFs) are fabricated from jute fibers after pre-oxidation, carbonization and surface repair. This paper investigates the effects of pre-oxidation heating rate on jute fibers, and explores a repair method for surface defects of CFs in C/C composite. The results show the reaction mechanism of jute fibers in air is not changed at higher pre-oxidation heating rates while a low heating rate is still required as the oxidation of jute fibers cannot be fully achieved under rapid heating. The tensile strength of CFs increases after repair with a 5% phenolic resin solution. Jute-based CFs play a positive role in C/C composite performance through crack bridging and deflection.

  8. Heating rate and induced thermotolerance in Mexican fruit fly (Diptera: Tephritidae) larvae, a quarantine pest of citrus and mangoes.

    PubMed

    Thomas, D B; Shellie, K C

    2000-08-01

    A bioassay and graduated temperature water baths were used to document the induction of thermotolerance in third-instar Mexican fruit fly, Anastrepha ludens (Loew). The 99% lethal time dose for larvae exposed to 44 degrees C core temperatures in artificial fruit is 61.5 min when a slow heating rate (120 min ramp) is applied, but only 41.9 min when a fast heating rate (15 min ramp) is applied. In electrophoretic profiles a heat inducible protein of molecular weight 32 kDa was detected in 76% of the larvae exposed to the slow ramp treatment, but only 42% of the larvae in the fast ramp treatment. Results from this research demonstrate that thermotolerance can be induced under conditions used to commercially disinfest fresh produce and highlight the necessity for specifying heating rates in quarantine treatment schedules.

  9. Coastal ocean optical influences on solar transmission and radiant heating rate

    NASA Astrophysics Data System (ADS)

    Chang, Grace C.; Dickey, Tommy D.

    2004-01-01

    An extensive set of physical and optical measurements is utilized to characterize the processes and quantify parameters that contribute to the variability of solar transmission, sea surface albedo, and radiant heating rate (RHR). This study is among the first to utilize multidisciplinary observations coupled with radiative transfer simulations to investigate the impact of optical properties on solar transmission, albedo, and heating in nearshore coastal waters. The data were collected from a shallow-water coastal mooring as part of the Hyperspectral Coastal Ocean Dynamics Experiment (HyCODE) in summer 2001. Over the 41-day time series, the average loss in solar radiation was 274 W m-2 for mean surface radiation of 365 W m-2 (average solar transmission of 21%). Quantitative coherence and principle component analyses suggest that cloud cover, chlorophyll concentration (Chl), and colored dissolved organic matter (CDOM) have the greatest impacts on solar transmission variability on timescales of ˜1 week. Radiative transfer simulations show that Chl, absorption, and attenuation have the most significant impact on solar transmission, whereas solar angle and cloud cover greatly influence albedo.

  10. Integration and software for thermal test of heat rate sensors. [space shuttle external tank

    NASA Technical Reports Server (NTRS)

    Wojciechowski, C. J.; Shrider, K. R.

    1982-01-01

    A minicomputer controlled radiant test facility is described which was developed and calibrated in an effort to verify analytical thermal models of instrumentation islands installed aboard the space shuttle external tank to measure thermal flight parameters during ascent. Software was provided for the facility as well as for development tests on the SRB actuator tail stock. Additional testing was conducted with the test facility to determine the temperature and heat flux rate and loads required to effect a change of color in the ET tank external paint. This requirement resulted from the review of photographs taken of the ET at separation from the orbiter which showed that 75% of the external tank paint coating had not changed color from its original white color. The paint on the remaining 25% of the tank was either brown or black, indicating that it had degraded due to heating or that the spray on form insulation had receded in these areas. The operational capability of the facility as well as the various tests which were conducted and their results are discussed.

  11. Development of a water boil-off spent-fuel calorimeter system. [To measure decay heat generation rate

    SciTech Connect

    Creer, J.M.; Shupe, J.W. Jr.

    1981-05-01

    A calorimeter system was developed to measure decay heat generation rates of unmodified spent fuel assemblies from commercial nuclear reactors. The system was designed, fabricated, and successfully tested using the following specifications: capacity of one BWR or PWR spent fuel assembly; decay heat generation range 0.1 to 2.5 kW; measurement time of < 12 h; and an accuracy of +-10% or better. The system was acceptance tested using a dc reference heater to simulate spent fuel assembly heat generation rates. Results of these tests indicated that the system could be used to measure heat generation rates between 0.5 and 2.5 kW within +- 5%. Measurements of heat generation rates of approx. 0.1 kW were obtained within +- 15%. The calorimeter system has the potential to permit measurements of heat generation rates of spent fuel assemblies and other devices in the 12- to 14-kW range. Results of calorimetry of a Turkey Point spent fuel assembly indicated that the assembly was generating approx. 1.55 kW.

  12. Influence of surrounding structures upon the aerodynamic and acoustic performance of the outdoor unit of a split air-conditioner

    NASA Astrophysics Data System (ADS)

    Wu, Chengjun; Liu, Jiang; Pan, Jie

    2014-07-01

    DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics(CFD) and computational aerodynamic acoustics(CAA) simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures(i.e. the heat sink, the bell-mouth type shroud and the outlet grille) upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring's size and throat's depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %(i.e. 100 m3·h-1) at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.

  13. An Aerodynamic Analysis of a Spinning Missile with Dithering Canards

    NASA Technical Reports Server (NTRS)

    Meakin, Robert L.; Nygaard, Tor A.

    2003-01-01

    A generic spinning missile with dithering canards is used to demonstrate the utility of an overset structured grid approach for simulating the aerodynamics of rolling airframe missile systems. The approach is used to generate a modest aerodynamic database for the generic missile. The database is populated with solutions to the Euler and Navier-Stokes equations. It is used to evaluate grid resolution requirements for accurate prediction of instantaneous missile loads and the relative aerodynamic significance of angle-of-attack, canard pitching sequence, viscous effects, and roll-rate effects. A novel analytical method for inter- and extrapolation of database results is also given.

  14. Heat pipe cooling system with sensible heat sink

    NASA Technical Reports Server (NTRS)

    Silverstein, Calvin C.

    1988-01-01

    A heat pipe cooling system which employs a sensible heat sink is discussed. With this type of system, incident aerodynamic heat is transported via a heat pipe from the stagnation region to the heat sink and absorbed by raising the temperature of the heat sink material. The use of a sensible heat sink can be advantageous for situations where the total mission heat load is limited, as it is during re-entry, and a suitable radiation sink is not available.

  15. Strengthened PAN-based carbon fibers obtained by slow heating rate carbonization

    PubMed Central

    Kim, Min-A; Jang, Dawon; Tejima, Syogo; Cruz-Silva, Rodolfo; Joh, Han-Ik; Kim, Hwan Chul; Lee, Sungho; Endo, Morinobu

    2016-01-01

    Large efforts have been made over the last 40 years to increase the mechanical strength of polyacrylonitrile (PAN)-based carbon fibers (CFs) using a variety of chemical or physical protocols. In this paper, we report a new method to increase CFs mechanical strength using a slow heating rate during the carbonization process. This new approach increases both the carbon sp3 bonding and the number of nitrogen atoms with quaternary bonding in the hexagonal carbon network. Theoretical calculations support a crosslinking model promoted by the interstitial carbon atoms located in the graphitic interlayer spaces. The improvement in mechanical performance by a controlled crosslinking between the carbon hexagonal layers of the PAN based CFs is a new concept that can contribute further in the tailoring of CFs performance based on the understanding of their microstructure down to the atomic scale. PMID:27004752

  16. Strengthened PAN-based carbon fibers obtained by slow heating rate carbonization.

    PubMed

    Kim, Min-A; Jang, Dawon; Tejima, Syogo; Cruz-Silva, Rodolfo; Joh, Han-Ik; Kim, Hwan Chul; Lee, Sungho; Endo, Morinobu

    2016-03-23

    Large efforts have been made over the last 40 years to increase the mechanical strength of polyacrylonitrile (PAN)-based carbon fibers (CFs) using a variety of chemical or physical protocols. In this paper, we report a new method to increase CFs mechanical strength using a slow heating rate during the carbonization process. This new approach increases both the carbon sp(3) bonding and the number of nitrogen atoms with quaternary bonding in the hexagonal carbon network. Theoretical calculations support a crosslinking model promoted by the interstitial carbon atoms located in the graphitic interlayer spaces. The improvement in mechanical performance by a controlled crosslinking between the carbon hexagonal layers of the PAN based CFs is a new concept that can contribute further in the tailoring of CFs performance based on the understanding of their microstructure down to the atomic scale.

  17. Pyrolysis characteristics of organic components of municipal solid waste at high heating rates.

    PubMed

    Zheng, Jiao; Jin, Yu-Qi; Chi, Yong; Wen, Jun-Ming; Jiang, Xu-Guang; Ni, Ming-Jiang

    2009-03-01

    The pyrolysis characteristics of six representative organic components of municipal solid waste (MSW) and their mixtures were studied in a specially designed thermogravimetric analysis apparatus with a maximum recorded heating rate of 864.8 degrees Cmin(-1). The pyrolysis behavior of individual components was described by the Avrami-Erofeev equation. The influence of final temperature on individual components was studied, and it was concluded that final temperature was a factor in reaction speed and intensity, but that it played only a limited role in determining the reaction mechanism. The interactions between different components were evaluated, and it was concluded that the interaction between homogeneous materials was minimal, whereas the interaction between polyethylene and biomass was significant.

  18. Evaluating heat rate modifications with the EPRI Plant Modification Operating Savings (PMOS) model

    SciTech Connect

    Fahd, G.; O`Connor, D.

    1997-03-01

    The Electric Power Research Institute (EPRI) developed the Plant Modification Operating Savings model (PMOS) to overcome the shortcomings of conventional planning tools in capturing the value of small-scale plant modifications. PMOS focuses on a single plant and, using readily available cost and performance data, determines the value of a modification at that plant to the system. PMOS provides decision-makers with accurate results to help select the projects with highest value to the system. It is a powerful, yet easy-to-use, computer model that is a useful addition to the utility planning toolkit. This paper discusses the PMOS use to evaluate plant heat rate modifications and describes the model`s methodology and applications.

  19. Heating rate and electrode charging measurements in a scalable, microfabricated, surface-electrode ion trap

    NASA Astrophysics Data System (ADS)

    Allcock, D. T. C.; Harty, T. P.; Janacek, H. A.; Linke, N. M.; Ballance, C. J.; Steane, A. M.; Lucas, D. M.; Jarecki, R. L.; Habermehl, S. D.; Blain, M. G.; Stick, D.; Moehring, D. L.

    2012-06-01

    We characterise the performance of a surface-electrode ion "chip" trap fabricated using established semiconductor integrated circuit and micro-electro-mechanical-system (MEMS) microfabrication processes, which are in principle scalable to much larger ion trap arrays, as proposed for implementing ion trap quantum information processing. We measure rf ion micromotion parallel and perpendicular to the plane of the trap electrodes, and find that on-package capacitors reduce this to ≲10 nm in amplitude. We also measure ion trapping lifetime, charging effects due to laser light incident on the trap electrodes, and the heating rate for a single trapped ion. The performance of this trap is found to be comparable with others of the same size scale.

  20. Diabatic heating rate estimates from European Centre for Medium-Range Weather Forecasts analyses

    NASA Technical Reports Server (NTRS)

    Christy, John R.

    1991-01-01

    Vertically integrated diabatic heating rate estimates (H) calculated from 32 months of European Center for Medium-Range Weather Forecasts daily analyses (May 1985-December 1987) are determined as residuals of the thermodynamic equation in pressure coordinates. Values for global, hemispheric, zonal, and grid point H are given as they vary over the time period examined. The distribution of H is compared with previous results and with outgoing longwave radiation (OLR) measurements. The most significant negative correlations between H and OLR occur for (1) tropical and Northern-Hemisphere mid-latitude oceanic areas and (2) zonal and hemispheric mean values for periods less than 90 days. Largest positive correlations are seen in periods greater than 90 days for the Northern Hemispheric mean and continental areas of North Africa, North America, northern Asia, and Antarctica. The physical basis for these relationships is discussed. An interyear comparison between 1986 and 1987 reveals the ENSO signal.