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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high speed flow fields.

Porro, A. R.↗
NASA NTRS1991

A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high-speed flowfields.

Porro, A. R.↗
NASA NTRS1991

Development of a laser-induced heat flux technique for measurement of convective heat transfer coefficients in a supersonic flowfield

A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the load surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimental results agreed reasonably well with theoretical predictions of convective heat transfer of flat plate laminar boundary layers. The results indicate that this non-intrusive optical measurement technique has the potential to obtain high quality surface convective heat transfer measurements in high speed flowfields.

Porro, A. Robert↗
NASA NTRS1987

Influence of ventilated shrouds on the convective heat transfer to a circular cylinder

Convective heat transfer to shrouded cylinders in transverse flow has been studied over the Reynolds number range 2000-20,000. The influence of shroud ventilation, relative shroud diameters, and orientation of the ventilation holes was studied. In some cases, average inner-cylinder Nusselt numbers were found to exceed the comparable bare-cylinder values by as much as 50 percent. Cylinder heat convection was influenced more by the degree of ventilation and shroud diameter than by hole orientation. An equivalent inner bare cylinder diameter, based on degree of shroud ventilation and shroud diameter, was developed which can be useful in shroud design studies.

Daryabeigi, Kamran↗
NASA NTRS2002

Convective Heat Transfer in the Reusable Solid Rocket Motor of the Space Transportation System

This simulation involved a two-dimensional axisymmetric model of a full motor initial grain of the Reusable Solid Rocket Motor (RSRM) of the Space Transportation System (STS). It was conducted with CFD (computational fluid dynamics) commercial code FLUENT. This analysis was performed to: a) maintain continuity with most related previous analyses, b) serve as a non-vectored baseline for any three-dimensional vectored nozzles, c) provide a relatively simple application and checkout for various CFD solution schemes, grid sensitivity studies, turbulence modeling and heat transfer, and d) calculate nozzle convective heat transfer coefficients. The accuracy of the present results and the selection of the numerical schemes and turbulence models were based on matching the rocket ballistic predictions of mass flow rate, head end pressure, vacuum thrust and specific impulse, and measured chamber pressure drop. Matching these ballistic predictions was found to be good. This study was limited to convective heat transfer and the results compared favorably with existing theory. On the other hand, qualitative comparison with backed-out data of the ratio of the convective heat transfer coefficient to the specific heat at constant pressure was made in a relative manner. This backed-out data was devised to match nozzle erosion that was a result of heat transfer (convective, radiative and conductive), chemical (transpirating), and mechanical (shear and particle impingement forces) effects combined.

Ahmad, Rashid A.↗
NASA NTRS1971

A general stagnation-point convective heating equation for arbitrary gas mixtures

The stagnation-point convective heat transfer to an axisymmetric blunt body for arbitrary gases in chemical equilibrium was investigated. The gases considered were base gases of nitrogen, oxygen, hydrogen, helium, neon, argon, carbon dioxide, ammonia, and methane and 22 gas mixtures composed of the base gases. Enthalpies ranged from 2.3 to 116.2 MJ/kg, pressures ranged from 0.001 to 100 atmospheres, and the wall temperatures were 300 and 1111 K. A general equation for the stagnation-point convective heat transfer in base gases and gas mixtures was derived and is a function of the mass fraction, the molecular weight, and a transport parameter of the base gases. The relation compares well with present boundary-layer computer results and with other analytical and experimental results. In addition, the analysis verified that the convective heat transfer in gas mixtures can be determined from a summation relation involving the heat transfer coefficients of the base gases. The basic technique developed for the prediction of stagnation-point convective heating to an axisymmetric blunt body could be applied to other heat transfer problems.

Sutton, K.↗
NASA NTRSDate not supplied

Stagnation Point Convective Heating Correlations for Entry Into H2/He Atmospheres

New convective heating correlations have been developed over a broad range of entry conditions into H2/He atmospheres. The correlations are based on calculations of stagnation point convective heat fluxes over a large range of velocities, densities, and effective nose radii. The heat fluxes and corresponding flowfields are computed using NASA’s hypersonic computational fluid dynamics code, DPLR. Cases in this study have been computed using both a temperaturelimited, radiative equilibrium wall and a cold wall temperature boundary condition. The results for the scaled heat flux, as a function of the difference in freestream and wall enthalpies, show a clear deviation from the linear trend predicted by the method of Sutton and Graves. Therefore, updated non-linear correlations are proposed for the prediction of stagnation point convective heat fluxes. Generally, these updated correlations predict lower heat loads and therefore smaller required TPS thicknesses when compared to previous correlations for a range of test cases in the Neptune, Saturn, and Uranus atmospheres.

Alex T. Carroll↗
NASA NTRSDate not supplied

Stagnation Point Convective Heating Correlations for Entry Into H2/He Atmospheres

New convective heating correlations have been developed over a broad range of entry conditions into H2/He atmospheres. The correlations are based on calculations of stagnation point convective heat fluxes over a large range of velocities, densities, and effective nose radii. The heat fluxes and corresponding flow fields are computed using NASA’s hypersonic computational fluid dynamics code, DPLR. Cases in this study have been computed using both a temperature limited, radiative equilibrium wall and a cold wall temperature boundary condition. The results for the scaled heat flux, as a function of the difference in freestream and wall enthalpies, show a clear deviation from the linear trend predicted by the method of Sutton and Graves. Therefore, updated non-linear correlations are proposed for the prediction of stagnation point convective heat fluxes. Generally, these updated correlations predict lower heat loads and therefore smaller required TPS thicknesses when compared to previous correlations for a range of test cases in the Neptune, Saturn, and Uranus atmospheres.

Alex T. Carroll↗
NASA NTRS1980

STS-1 Nominal Cycle 3 March/April Launch, Ascent Base Convective Heating Environments

Ascent base convective heating environments were determined for the nominal ascent trajectory for the STS-1 Cycle 3 March/April launch period. Both first and second stage environments are defined for all base heating DFI locations and design body points of interest. An identical format to the STS-1 dispersed trajectory environment was followed throughout. As expected, STS-1 nominal environments are generally less severe than those determined for the high loft and low loft dispersed trajectory conditions. The reduction in cold wall heating with the nominal trajectory varies for each base location analyzed, but, in general, was approximately twenty percent.

Bender, R. L., Jr.↗
NASA NTRS1973

Chemical and morphological changes of reusable surface insulation coatings as a function of convectively heated cyclic testing

The effects of convective heating upon reusable surface insulation coatings were studied utilizing scanning electron microscopy, X-ray fluorescence, and X-ray diffraction. Samples of coated silica, mullite, and ceramic mullite fiber were cycled in an arc plasma stream up to 15 times for 15 minutes per cycle at surface temperatures simulating those on the space shuttle vehicle. The surfaces of ceramic mullite fiber and mullite coatings were roughened substantially by the convectively heated environment while the silica was significantly smoothed after testing. Scanning electron microscopy also showed surface cracking of varying degrees in all of the coatings. The surface chemistry of the coatings as examined by X-ray fluorescence revealed that significant changes in composition were occurring during cycling, particularly within the mullite coating.

Leiser, D. B.↗
NASA NTRS1993

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

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

Kim, K.↗
NASA NTRS1978

SSV Generic OFT first stage ascent base convective heating environments

Space Shuttle Vehicle (SSV) base convective heating environments during the recirculated flow time segment of first stage ascent were determined for the Generic OFT trajectory and performance conditions. These environments are presented in the attachments as cold wall convective heat transfer coefficients for individual or groups of design points for all affected SSV base surfaces. Two gas recovery temperatures applicable to upper and lower base region surfaces are also included. The environments were based upon magnitudes and trends from analysis of data taken during Base Heating Tests IH-39, IH-75, and IH-83. The plume heating trajectory and performance data were supplied by Rockwell International for both the OFT-1 Generic Mission A and Mission C.

Bender, R. L., Jr.↗
NASA NTRS1994

An axisymmetric analog two-layer convective heating procedure with application to the evaluation of Space Shuttle Orbiter wing leading edge and windward surface heating

A numerical procedure for predicting the convective heating rate of hypersonic reentry vehicles is described. The procedure, which is based on the axisymmetric analog, consists of obtaining the three-dimensional inviscid flowfield solution; then the surface streamlines and metrics are calculated using the inviscid velocity components on the surface; finally, an axisymmetric boundary layer code or approximate convective heating equations are used to evaluate heating rates. This approach yields heating predictions to general three-dimensional body shapes. The procedure has been applied to the prediction of the wing leading edge heating to the Space Shuttle Orbiter. The numerical results are compared with the results of heat transfer testing (OH66) of an 0.025 scale model of the Space Shuttle Orbiter configuration in the Calspan Hypersonic Shock Tunnel (HST) at Mach 10 and angles of attack of 30 and 40 degrees. Comparisons with STS-5 flight data at Mach 9.15 and angle of attack of 37.4 degrees and STS-2 flight data at Mach 12.86 and angle of attack of 39.7 degrees are also given.

Wang, K. C.↗