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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Aeroheating Testing of the Mars Sample Return Earth Entry System with Surface Roughness

The Mars Sample Return Earth Entry System is a mission concept which would be the first NASA entry vehicle to utilize a woven thermal protection system as well as a 52.5 degree sphere-cone forebody geometry. Due to its novel design, historic experimental data sets were insufficient to validate the models used to characterize the expected aerothermal environment. A wind tunnel test campaign was funded by the Mars Sample Return Earth Entry System project in the NASA Langley 20-Inch Mach 6 Air Tunnel in order to obtain validation data. The December 2023 test entry of this campaign sought to obtain thermographic data to capture the impact of supersonic flow near woven surface roughness elements on convective heating augmentation, which was the largest remaining uncertainty in aerothermal design of the Earth Entry System. Data obtained were in family with prior results obtained on identical woven patterns without supersonic flow present at roughness elements, and it was found that this presence of supersonic flow did not have a noticeable effect on surface convective heating augmentation. Data were directly leveraged to support the NASA Mars Sample Return flight program and this data set is valuable for validating computational solutions on roughness-resolved grids.

Mars Sample Return↗
NASA NTRSDate not supplied

Aeroheating Testing of the Mars Sample Return Earth Entry System with Surface Roughness

The Mars Sample Return Earth Entry System is a mission concept which would be the first NASA entry vehicle to utilize a woven thermal protection system as well as a 52.5 degree sphere-cone forebody geometry. Due to its novel design, historic experimental data sets were insufficient to validate the models used to characterize the expected aerothermal environment. A wind tunnel test campaign was funded by the Mars Sample Return Earth Entry System project in the NASA Langley 20-Inch Mach 6 Air Tunnel in order to obtain validation data. The December 2023 test entry of this campaign sought to obtain thermographic data to capture the impact of supersonic flow near woven surface roughness elements on convective heating augmentation, which was the largest remaining uncertainty in aerothermal design of the Earth Entry System. Data obtained were in family with prior results obtained on identical woven patterns without supersonic flow present at roughness elements, and it was found that this presence of supersonic flow did not have a noticeable effect on surface convective heating augmentation. Data were directly leveraged to support the NASA Mars Sample Return flight program and this data set is valuable for validating computational solutions on roughness-resolved grids.

Mars Sample Return↗
NASA NTRS1984

Bearing tester fit analysis

A NASTRAN model of the Bearing Tester was developed to determine the fit of its components while in use. The model was executed for three loading conditions involving appropriate thermal and pressure loading throughout: rotation (30,000 rpm), rotation with 5000 lb axial shaft loading, and rotation with 2000 lb lateral shaft loading. A 30 deg slice of the Bearing Tester was modeled with solid isoparametric elements (CIHEX). Five more slices were generated to form a 180 deg symmetrical half. Each component was modeled separately for two reasons: (1) in the heat transfer version each component required covering with appropriate heat transfer coefficient elements, and (2) for the displacement version each component required independent radial expansion with respect to adjacent components. The components are connected at fastener and bearing locations axially and/or tangentially. Differences in radial displacements of adjacent cylindrical surfaces were calculated and added to those differences calculated for 180 deg opposite locations to determine the diametric change.

Source record↗
NASA NTRS1972

Thermal volatilization studies on lunar samples.

The results of thermal volatilization studies on lunar basalts, breccias, and soils, carried out to measure the depletion of selected elemental abundances during heating under vacuum, are evaluated. The kinetics of K, Rb, and Pb loss are found to be sufficiently fast to permit vaporization and loss of these elements during the production of impact glasses. There is little probability that lunar basalt flows have lost a significant percentage of K, Rb, and Na by volatilization, unless the flow is extensively stirred. The uniformly low Na concentrations of mare basalts cannot be attributed to post eruption vaporization and loss on Na.

Gibson, E. K., Jr.↗
NASA NTRS2012

Thermal Stir Welder

A welding apparatus is provided for forming a weld joint between first and second elements of a workpiece. The apparatus heats the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding mixer, to remove any dendritic-type weld microstructures introduced into the interface material during heating.

Ding, R. Jeffrey↗
NASA NTRS1982

Heater Composite Measures Heat Transfer

Composite consisting of commercially available elements has been developed to measure heat transfer. Composite provides a simple, convenient, low-cost device for use in heat-transfer work for rapid evaluation of thermal performance of both flat and simply curved objects. Device utilizes available off-the-shelf materials and provides a convenient method, with good resolution of local temperatures and heat transfer, with measurement accuracy at near-normal room conditions.

Hippensteele, S. A.↗
NASA NTRS1994

Transportation of volatile elements in thermally evolving planetesimals: An important role of metallic iron

Ordinary chondrites are considered to have experienced thermal metamorphism in small bodies. We are interested in behaviors of volatile elements in such a kind of thermally evolving planetesimals. Volatile elements generally have high vapor pressures at high temperature. In porous bodies, with a high gas permeability, volatile elements are transported efficiently over a long range. Behavior of volatile elements transported by permeable gas flow can be handled by an equation whose form is similar to that of the equation of thermal diffusion. We can follow transportation of heats and volatile elements in planetesimals, when parameters in these equations, initial conditions and chemical behavior of volatile elements are given. Recently, we discovered that nitrogen in equilibrated H-chondrites is mainly trapped in taenite (f.c.c. Fe-Ni), probably dissolved in interstitial sites. Fegley suggests that metallic iron cannot trap nitrogen in the solar nebula gas due to its very low nitrogen partial pressure. Approximately 1 bar of nitrogen pressure is required to explain the nitrogen content in taenite. We may expect high nitrogen gas partial pressure (possibly produced by vaporization of nitrogen-bearing solids such as organic materials) at the interior of thermally evolving planetesimals. Kinetic behavior of nitrogen in taenite suggests that it can easily be equilibrated with the ambient nitrogen gas at temperatures of approximately 500 C or higher. We consider that nitrogen is trapped in taenite through a nitrogen redistribution process occurred during the thermal metamorphic event.

Hashizume, K.↗
NASA NTRSDate not supplied

Improved Heat Transfer Prediction for High-Speed Flows over Blunt Bodies using Adaptive Mixed-Element Unstructured Grids

Aerothermodynamic prediction is important for the design and analysis of many aerospace vehicles. Computational Fluid Dynamics (CFD) tools used for these predictions commonly rely on structured shock-aligned grids due to the strong shocks exhibited at high speeds. This work details the incorporation of an improved HLLE++ scheme for both perfect gas and thermochemical nonequilibrium flows which robustly captures shock waves on both non-shock-aligned and shock-aligned grids. The HLLE++ scheme reduces the impact of eigenvalue limiting on flow solutions which is required for Roe's scheme for high Mach number flows. An adapted grid approach is also demonstrated using mixed-element unstructured grids to improve heat prediction. Thin prismatic boundary layers are used with tetrahedra in the farfield and for capturing shock waves. Various results are presented for hypersonic flows over blunt bodies including cylinders, spheres, and capsules.

CFD↗
NASA NTRSDate not supplied

Improved Heat Transfer Prediction for High-Speed Flows over Blunt Bodies using Adaptive Mixed-Element Unstructured Grids

Aerothermodynamic prediction is important for the design and analysis of many aerospace vehicles. Computational Fluid Dynamics (CFD) tools used for these predictions commonly rely on structured shock-aligned grids due to the strong shocks exhibited at high speeds. This work details the incorporation of an improved HLLE++ scheme for both perfect gas and thermochemical nonequilibrium flows which robustly captures shock waves on both non-shock-aligned and shock-aligned grids. The HLLE++ scheme reduces the impact of eigenvalue limiting on flow solutions which is required for Roe's scheme for high Mach number flows. An adapted grid approach is also demonstrated using mixed-element unstructured grids to improve heat prediction. Thin prismatic boundary layers are used with tetrahedra in the farfield and for capturing shock waves. Various results are presented for hypersonic flows over blunt bodies including cylinders, spheres, and capsules.

CFD↗
NASA NTRS1980

Subcontracted activities related to TES for building heating and cooling

The subcontract program elements related to thermal energy storage for building heating and cooling systems are outlined. The following factors are included: subcontracts in the utility load management application area; life and stability testing of packaged low cost energy storage materials; and development of thermal energy storage systems for residential space cooling. Resistance storage heater component development, demonstration of storage heater systems for residential applications, and simulation and evaluation of latent heat thermal energy storage (heat pump systems) are also discussed. Application of thermal energy storage for solar application and twin cities district heating are covered including an application analysis and technology assessment of thermal energy storage.

Martin, J.↗
NASA NTRS2011

Non-Venting Thermal and Humidity Control for EVA Suits

Future EVA suits need processes and systems to control internal temperature and humidity without venting water to the environment. This paper describes an absorption-based cooling and dehumidification system as well as laboratory demonstrations of the key processes. There are two main components in the system: an evaporation cooling and dehumidification garment (ECDG) that removes both sensible heat and latent heat from the pressure garment, and an absorber radiator that absorbs moisture and rejects heat to space by thermal radiation. This paper discusses the overall design of both components, and presents recent data demonstrating their operation. We developed a design and fabrication approach to produce prototypical heat/water absorbing elements for the ECDG, and demonstrated by test that these elements could absorb heat and moisture at a high flux. Proof-of-concept tests showed that an ECDG prototype absorbs heat and moisture at a rate of 85 W/ft under conditions that simulate operation in an EVA suit. The heat absorption was primarily due to direct absorption of water vapor. It is possible to construct large, flexible, durable cooling patches that can be incorporated into a cooling garment with this system. The proof-of-concept test data was scaled to calculate area needed for full metabolic loads, thus showing that it is feasible to use this technology in an EVA suit. Full-scale, lightweight absorber/radiator modules have also been built and tested. They can reject heat at a flux of 33 W/ft while maintaining ECDG operation at conditions that will provide a cool and dry environment inside the EVA suit.

Izenson, Mike↗
NASA NTRS1972

An out-of-core thermionic-converter system for nuclear space power.

Reexamination of designs of nuclear thermionic space power systems with the converter outside the reactor in the perspective of recent advances in heat-transfer methods, materials, converter performance, and radiation design. The 40- to 70-kW(e) power range is treated. The configuration is found to meet the constraints of readily available launch vehicles. It allows for off-design operation including startup, shutdown, and possible emergency conditions; provides tolerance of failure by extensive use of modular, redundant elements; incorporates and uses heat pipes in a fashion that reduces the need for extensive in-pile testing of system components; and uses thermionic converters, nuclear fuel elements, and heat-transfer devices in a geometrical form adapted from existing incore thermionic system designs.

Breitwieser, R.↗
NASA NTRS2012

Radiation Coupling with the FUN3D Unstructured-Grid CFD Code

The HARA radiation code is fully-coupled to the FUN3D unstructured-grid CFD code for the purpose of simulating high-energy hypersonic flows. The radiation energy source terms and surface heat transfer, under the tangent slab approximation, are included within the fluid dynamic ow solver. The Fire II flight test, at the Mach-31 1643-second trajectory point, is used as a demonstration case. Comparisons are made with an existing structured-grid capability, the LAURA/HARA coupling. The radiative surface heat transfer rates from the present approach match the benchmark values within 6%. Although radiation coupling is the focus of the present work, convective surface heat transfer rates are also reported, and are seen to vary depending upon the choice of mesh connectivity and FUN3D ux reconstruction algorithm. On a tetrahedral-element mesh the convective heating matches the benchmark at the stagnation point, but under-predicts by 15% on the Fire II shoulder. Conversely, on a mixed-element mesh the convective heating over-predicts at the stagnation point by 20%, but matches the benchmark away from the stagnation region.

Wood, William A.↗
NASA NTRS1979

Efficiency optimization of a thermionic converter array

Intensive study of the outer planets of the solar system requires the use of nuclear power for electric propulsion of spacecraft. Among the power conversion devices being considered for this application are thermionic converters. This paper presents the results of computer modeling of thermionic converters to identify the major design variables and select an optimum size for each of the thermionic converters for the power conversion system under consideration. Among the variables investigated were electrical and thermal losses in electrodes, leads and heat chokes. Those elements which minimized the electrical losses tended to increase thermal losses and system weight. Overall mechanical design and relative positioning of components also had impacts on converter efficiency and the power subsystem weight. Numerical calculations were made using the computer heat transfer code SINDA coupled with electrical loss parameters. The results of the computations are presented in this paper.

Kuo, Y. S.↗
NASA NTRS1982

Study of a heat rejection system for the Nuclear Electric Propulsion (NEP) spacecraft

Two different heat pipe radiator elements, one intended for use with the power conversion subsystem of the NASA funded nuclear electric propulsion (NEP) spacecraft, and one intended for use with the DOE funded space power advanced reactor (SPAR) system were tested and evaluated. The NEP stainless steel/sodium heat pipe was 4.42 meters long and had a 1 cm diameter. Thermal performance testing at 920 K showed a non-limited power level of 3560 watts, well in excess of the design power of 2600 watts. This test verified the applicability of screen arteries for use in long radiator heat pipes. The SPAR titanium/potassium heat pipe was 5.5 meters long and had a semicircular crossection with a 4 cm diameter. Thermal performance testing at 775 K showed a maximum power level of 1.86 kW, somewhat short of the desired 2.6 kW beginning of life design requirement. The reduced performance was shown to be the result of the inability of the evaporator wall wick (shot blasted evaporator wall) to handle the required liquid flow.

Ernest, D. M.↗
NASA NTRS1987

Use of a liquid-crystal, heater-element composite for quantitative, high-resolution heat transfer coefficients on a turbine airfoil, including turbulence and surface roughness effects

Local heat transfer coefficients were measured along the midchord of a three-times-size turbine vane airfoil in a static cascade operated at roon temperature over a range of Reynolds numbers. The test surface consisted of a composite of commercially available materials: a Mylar sheet with a layer of cholestric liquid crystals, which change color with temperature, and a heater made of a polyester sheet coated with vapor-deposited gold, which produces uniform heat flux. After the initial selection and calibration of the composite sheet, accurate, quantitative, and continuous heat transfer coefficients were mapped over the airfoil surface. Tests were conducted at two free-stream turbulence intensities: 0.6 percent, which is typical of wind tunnels; and 10 percent, which is typical of real engine conditions. In addition to a smooth airfoil, the effects of local leading-edge sand roughness were also examined for a value greater than the critical roughness. The local heat transfer coefficients are presented for both free-stream turbulence intensities for inlet Reynolds numbers from 1.20 to 5.55 x 10 to the 5th power. Comparisons are also made with analytical values of heat transfer coefficients obtained from the STAN5 boundary layer code.

Hippensteele, Steven A.↗