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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Fully Implicit Ablation and Thermal Response Program for Spacecraft Heatshield Analysis

A fully implicit ablation and thermal response program has been developed for the simulation of one-dimensional transient transport of thermal energy in a multilayer stack of isotropic materials and structure which can ablate from a front surface and decompose in-depth. Equations and numerical procedures for solution are described. Solutions are compared with those of Aerotherm Charring Material Thermal Response and Ablation Program, and with the arcjet data. The code is numerically more stable, and solves much wider range of problems compared with the existing explicit code. Applications of the code for the analysis of aeroshell heatshields of Stardust, Mars 2001, and Mars Microprobe using the advanced Light Weight Ceramic Ablators developed at the NASA Ames Research Center are presented and discussed in detail.

Chen, Y. K.↗
NASA NTRS1987

Using the thermal infrared multispectral scanner (TIMS) to estimate surface thermal responses

A series of measurements was conducted over the H.J. Andrews, Oregon, experimental coniferous forest, using airborne thermal infrared multispectral scanner (TIMS). Flight lines overlapped, with a 28-min time difference between flight lines. Concurrent radiosonde measurements of atmospheric profiles of air temperature and moisture were used for atmospheric radiance corrections of the TIMS data. Surface temperature differences over time between flight lines were used to develop thermal response numbers (TRNs) which characterized the thermal response (in KJ/sq m/C, where K is the measured incoming solar radiation) of the different surface types. The surface types included a mature forest (canopy dominated by dense crowns of Pseudosuga menziesii, with a secondary canopy of dense Tsuga heterophylla, and also a tall shrub layer of Acer circinatum) and a two-year-old clear-cut. The temperature distribution, within TIMS thermal images was found to reflect the surface type examined. The clear-cut surface had the lowest TRN, while mature Douglas fir the highest.

Luvall, J. C.↗
NASA NTRS1982

Advances in Moire interferometry for thermal response of composites

An experimental technique for the precise measurement of the thermal response of both sides of a laminated composite coupon specimen uses Moire interferometry with fringe multiplication which yields a sensitivity of 833 nm (32.8 micro in.) per fringe. The reference gratings used are virtual gratings and are formed by partially mirrorized glass prisms in close proximity to the specimen. Results are compared with both results obtained from tests which used Moire interferometry on one side of composite laminates, and with those predicted by classical lamination theory. The technique is shown to be capable of producing the sensitivity and accuracy necessary to measure a wide range of thermal responses and to detect small side to side variations in the measured response. Tests were conducted on four laminate configurations of T300/5208 graphite epoxy over a temperature range of 297 K (75 F) to 422 K (300 F). The technique presented allows for the generation of reference gratings for temperature regimes well outside that used in these tests.

Brooks, E. W., Jr.↗
NASA NTRSDate not supplied

LOFTID Aeroshell Thermal Response Uncertainty Analysis Utilizing the End-to-End Monte Carlo Approach

A probabilistic thermal margin process has been performed to design the flexible thermal protection system (FTPS) and select entry trajectory constraints given an acceptable risk level for the Low-Earth Orbit Flight Test of and Inflatable Decelerator (LOFTID) project. Uncertainties exist in atmospheric entry aeroheating environments and the predicted thermal response of thermal protection system (TPS) material. Entry vehicle TPS is often over-sized to mitigate uncertainty by combining conservative bounding scenarios together. The probabilistic thermal margin process allows engineers to make informed aeroshell design, flight design, and FTPS performance risk trades while preventing excessive FTPS margin from being applied. This paper describes the uncertainty analysis methodology used to carry out a probabilistic thermal margin process used for LOFTID’s aeroshell and explains how the calculated probability of exceeding flight allowable temperatures is used to design the FTPS and establish nominal flight design constraints. This probabilistic thermal margin process had never been applied to entry, decent, and landing design for a flown entry vehicle and it is one of the LOFTID project’s goals to demonstrate its merits.

Steven Andrew Tobin↗
NASA NTRS1982

An analysis of thermal response factors and how to reduce their computational time requirement

Te RESFAC2 version of the Thermal Response Factor Program (RESFAC) is the result of numerous modifications and additions to the original RESFAC. These modifications and additions have significantly reduced the program's computational time requirement. As a result of this work, the program is more efficient and its code is both readable and understandable. This report describes what a thermal response factor is; analyzes the original matrix algebra calculations and root finding techniques; presents a new root finding technique and streamlined matrix algebra; supplies ten validation cases and their results.

Wiese, M. R.↗
NASA NTRS1981

Thermal response of the F region ionosphere in artificial modification experiments by HF radio waves

The thermal response of the nighttime F region ionosphere to local heating by HF radio waves has been observed with the incoherent scatter radar at Arecibo, Puerto Rico. The observations consist of high-resolution space and time variation of the electron temperature as a high-power HF transmitter is switched on and off with a period 240 s. As soon as the HF transmitter is turned on, the electron temperature begins to rise rapidly in a narrow altitude region near 300 km, below the F2 layer peak. The electron temperature perturbation subsequently spreads over a broader altitude region. The observations are compared with the anticipated thermal response of the ionosphere based on numerical solutions of the coupled time-dependent heat conduction equations for the electron and composite ion gases and are found to be in good agreement over the entire altitude region covered by the observations.

Mantas, G. P.↗
NASA NTRS1988

Thermal Response Of Composite Insulation

Engineering model gives useful predictions. Pair of reports presents theoretical and experimental analyses of thermal responses of multiple-component, lightweight, porous, ceramic insulators. Particular materials examined destined for use in Space Shuttle thermal protection system, test methods and heat-transfer theory useful to chemical, metallurgical, and ceramic engineers needing to calculate transient thermal responses of refractory composites.

Stewart, David A.↗
NASA NTRS1992

Thermal response of rigid and flexible insulations and reflective coating in an aeroconvective heating environment

Described here is the thermal performance of rigid and flexible thermal protection systems considered for potential use in future Aeroassist Space Transfer Vehicles. The thermal response of these materials subjected to aeroconvective heating from a plasma arc is described. Properties that were measured included the thermal conductivity of both rigid and flexible insulations at various temperatures and pressures and the emissivity of the fabrics used in the flexible insulations. The results from computerized thermal analysis models describing the thermal response of these materials subjected to flight conditions are included.

Kourtides, D. A.↗
NASA NTRS1978

Thermal response behavior of boundary-layer flows

This paper presents an approximate, but general, analysis for the thermal response behavior of incompressible, constant property, laminar boundary layer flow over a smooth object of arbitrary shape. It encompasses the classic time-dependent Leveque problem as its special case. Comparisons with available data show that, for fluids with Prandtl number of the order of unity or larger, this analytical solution is able to provide reasonably accurate results for most engineering applications. Under certain restrictive conditions, it can also be used to predict the thermal response of a compressible boundary layer flow.

Lin, F. N.↗
NASA NTRS1979

Transient thermal response of ablating bodies

A numerical study of transient thermal response of a blunt-nosed axisymmetric body made of Teflon is presented using a two-layer thermal model. It is shown that phase change and transverse heat conduction have a considerable effect on the internal temperature field. Comparison of the numerical results with experimental data shows that the single-layer thermal model does not predict the real feature of the thermal field, whereas the results of the two-layer thermal model agree reasonably well with the experiment.

Arai, N.↗
NASA NTRS2016

Thermal Response of the Mars Science Laboratory Spacecraft During Entry, Descent and Landing

NASA’s Mars Science Laboratory (MSL) spacecraft successfully performed its Entry, Descent & Landing (EDL) phase on August 6, 2012. This paper presents the thermal response of the MSL spacecraft from EDL Initialization (5 days prior to Entry) to Rover touchdown on the surface of Mars. Temperature telemetry recorded during EDL is used to reconstruct the thermal response of the spacecraft to each EDL event. Temperature profiles for the Descent Stage and Rover hardware are presented and explained in the context of the changing EDL environments (aerothermal heating and convective cooling) and power states.

Novak, Keith S.↗
NASA NTRS1991

Thermal response of large area high temperature superconducting YBaCuO infrared bolometers

Thermal analysis of large area high temperature superconducting infrared detector operating in the equilibrium mode (bolometer) was performed. An expression for the temperature coefficient beta = 1/R(dR/dT) in terms of the thermal conductance and the thermal time constant of the detector were derived. A superconducting transition edge bolometer is a thermistor consisting of a thin film superconducting YBaCuO evaporated into a suitable thermally isolated substrate. The operating temperature of the bolometer is maintained close to the midpoint of the superconducting transition region where the resistance R has a maximum dynamic range. A detector with a strip configuration was analyzed and an expression for the temperature rise (delta T) above the ambient due to a uniform illumination with a source of power density was calculated. An expression for the thermal responsibility depends upon the spatial modulation frequency and the angular frequency of the incoming radiation. The problem of the thermal cross talk between different detector elements was addressed. In the case of monolithic HTS detector array with a row of square elements of dimensions 2a and CCD or CID readout electronics the thermal spread function was derived for different spacing between elements.

Khalil, Ali E.↗
NASA NTRS1985

Thermal Response of an Aeroassisted Orbital Transfer Vehicle with a Conical Drag Brake

As an aeroassisted orbital transfer vehicle (AOTV) goes through an aerobraking maneuver a significant amount of heat is generated. In this paper, the thermal response of a specific AOTV to this aerobrake heating is examined. The vehicle has a 70-deg, Conical drag-brake heat shield attached to a cylindrical body which contains the payload. The heat shield is made of ceramic fabric its thickness is varied from that of a thin cloth to a 1.5-cm blanket. The fabric thickness, the radiation absorptivity of the vehicle surface materials, and radiation from the wake are all significant parameters in the thermal response to the heating produced by the braking maneuver. The maximum temperatures occur In the vicinity of the interface between the body and the conical heat shield.

Pitts, W. C.↗
NASA NTRS1984

Thermal response of an aeroassisted orbital-transfer vehicle with a conical drag brake

As an aeroassisted orbital-transfer vehicle (AOTV) goes through an aerobraking maneuver, a significant amount of heat is generated. In this paper, the thermal response of a specific AOTV to this aerobrake heating is examined. The vehicle has a 70 deg, conical drag-brake heat shield attached to a cylindrical body which contains the payload. The heat shield is made of silica fabric. The heat-shield thickness is varied from that of a thin cloth to a 1.5-cm blanket. The fabric thickness, the radiation absorptivity of the vehicle surface materials, and radiation from the wake are all significant parameters in the thermal response to the heating produced by the braking maneuver. The maximum temperatures occur in the vicinity of the interface between the body and the conical heat shield.

Pitts, W. C.↗
NASA NTRS2009

Validation of PICA Ablation and Thermal-Response Model at Low Heat Flux

Phenolic Impregnated Carbon Ablator (PICA) was the forebody heatshield material on the Stardust sample-return capsule and is also a primary candidate material for the Mars Science Lander (MSL), the Orion Crew Module, and the SpaceX Dragon vehicle. As part of the heatshield qualification for Orion, physical and thermal properties of virgin and charred PICA were measured, and an ablation and thermal response model was developed. We validated the model by comparing it with recession and temperature data from stagnation arcjet tests conducted over a wide range of stagnation heat flux of 107 to 1102 W/sq cm. The effect of orthotropic thermal conductivity was evident in the thermal response of the arcjet models. In general, model predictions compared well with the data; however, the uncertainty of the recession prediction was greatest for heat fluxes below 200 W/sq cm. More recent MSL testing focused on the low heat flux regime of 45 to 250 W/sq cm. The new results confirm the recession uncertainty, especially for pressures below 6 kPa. In this work we focus on improving the model predictions for MSL and Orion tests below 250 W/sq cm.

Milos, Frank S.↗
NASA NTRS2012

An Analytical Solution for Transient Thermal Response of an Insulated Structure

An analytical solution was derived for the transient response of an insulated aerospace vehicle structure subjected to a simplified heat pulse. This simplified problem approximates the thermal response of a thermal protection system of an atmospheric entry vehicle. The exact analytical solution is solely a function of two non-dimensional parameters. A simpler function of these two parameters was developed to approximate the maximum structural temperature over a wide range of parameter values. Techniques were developed to choose constant, effective properties to represent the relevant temperature and pressure-dependent properties for the insulator and structure. A technique was also developed to map a time-varying surface temperature history to an equivalent square heat pulse. Using these techniques, the maximum structural temperature rise was calculated using the analytical solutions and shown to typically agree with finite element simulations within 10 to 20 percent over the relevant range of parameters studied.

Blosser, Max L.↗
NASA NTRS2007

The Use of the Airborne Thermal/Visible Land Application Sensor (ATLAS) to Determine the Thermal Response Numbers for Urban Areas

Although satellite data are very useful for analysis of the urban heat island effect at a coarse scale, they do not lend themselves to developing a better understanding of which surfaces across the city contribute or drive the development of the urban heat island effect. Analysis of thermal energy responses for specific or discrete surfaces typical of the urban landscape (e.g., asphalt, building rooftops, vegetation) requires measurements at a very fine spatial scale (i.e., < 15m) to adequately resolve these surfaces and their attendant thermal energy regimes. Additionally, very fine scale spatial resolution thermal infrared data, such as that obtained from aircraft, are very useful for demonstrating to planning officials, policy makers, and the general populace the benefits of the urban forest. These benefits include mitigating the urban heat island effect, making cities more aesthetically pleasing and more habitable environments, and aid in overall cooling of the community. High spatial resolution thermal data are required to quantify how artificial surfaces within the city contribute to an increase in urban heating and the benefit of cool surfaces (e.g., surface coatings that reflect much of the incoming solar radiation as opposed to absorbing it thereby lowering urban temperatures). The TRN (thermal response number)(Luvall and Holbo 1989) is a technique using aircraft remotely sensed surface temperatures to quantify the thermal response of urban surfaces. The TRN was used to quantify the thermal response of various urban surface types ranging from completely vegetated surfaces to asphalt and concrete parking lots for several cities in the United States.

Luvall, Jeffrey C.↗