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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Similarity tests of turbine vanes, effects of ceramic thermal barrier coatings

The role of material thermal conductivity was analyzed for its effect on the thermal performance of air-cooled gas turbine components coated with a ceramic thermal barrier material when tested at reduced temperatures and pressures. It is shown that the thermal performance can be evaluated reliably at reduced gas and coolant conditions; however, thermal conductivity corrections are required for the data at reduced conditions. Corrections for a ceramic thermal barrier coated vane are significantly different than for an uncoated vane. Comparison of uncorrected test data, therefore, would show erroneously that the thermal barrier coating was ineffective. When thermal conductivity corrections are applied to the test data these data are then shown to be representative of engine data and also show that the thermal barrier coating increases the vane cooling effectiveness by 12.5 percent.

Gladden, H. J.↗
NASA NTRS1980

Similarity tests of turbine vanes - Effects of ceramic thermal barrier coatings

The role of material thermal conductivity was analyzed for its effect on the thermal performance of air-cooled gas turbine components coated with a ceramic thermal barrier material when tested at reduced temperatures and pressures. This study shows that the thermal performance can be evaluated reliably at reduced gas and coolant conditions. However, thermal conductivity corrections are required for the data at reduced conditions. These corrections for a ceramic thermal barrier coated vane are significantly different than the corrections for an uncoated vane. Comparison of uncorrected test data, therefore, would show erroneously that the thermal barrier coating was ineffective. When thermal conductivity corrections are applied to the test data these data are then shown to be representative of engine data and also show that the thermal barrier coating increases the vane cooling effectiveness by 12.5 precent.

Gladden, H. J.↗
NASA NTRS2014

Fundamental Property Requirements for Thermal and Mechanical Response Analysis of Thermal Protection Materials and Systems

Spacecraft that are designed to reenter the Earth's atmosphere, or enter the atmosphere of another planet, require Thermal Protection Systems (TPS) in order to survive the extreme thermal environments during the atmospheric flight. Analytical modeling of thermal and mechanical response is a fundamental aspect of the design of TPS and development of TPS materials. The analyses are used to understand the response of the materials and systems under representative environments. Performing these analyses, and evaluating the results, requires a variety of fundamental inputs, including: thermal and mechanical material properties; predicted or measured ground test and flight environments; and information about adjacent structure or attachments. We explain the nature of the analyses, highlight the essential fundamental data that are required, and describe the impact of the accuracy in the input data on the final results. We also describe the important priorities in material characterization testing in support of analyses.

Squire, Thomas↗
NASA NTRS1998

Method for Molding Planar Billet of Thermally Insulative Material Into Predetermined Non-Planar Shape

A method and apparatus is discussed for molding thermal protection system (TPS) tiles for spacecraft. The apparatus and method include a bottom mold member defining a mold surface shaped like a surface of the spacecraft, e.g., the nose cap of wing leading edge, sought to be thermally protected. A flat billet of TPS material is positioned over the periphery of the mold surface, and a hollow weight element that has a periphery configured like the periphery of the mold surface is positioned on the billet. The billet is then heated in accordance with a predetermined heating regime, and during the heating process the weight of the weight element causes the billet to deform to assume the shape of the mold surface. If desired, a TUFI coating is impregnated into the billet prior to heating, and the coating is sintered to the billet during heating. After heating, a composite matrix material, e.g., a graphite or fiberglass cloth which is impregnated with epoxy or polimide, is bonded to the now-shaped tile to support the tile. Silicone can then be impregnated into the now-formed tile to provide flexibility of the tile.

Kolodziej, Paul↗
NASA NTRS2005

Lightweight Nonmetallic Thermal Protection Materials Technology (LNTPMT) Project

Contents include the following: Exploration systems research and technology program structure. Project objective. Overview of project. Candidate thermal protection system (PS) materials. Definition of reference missions and space environments. Technical performance metrics (TPMs).Testing (types of tests). Conclusion.

Flynn, Kevin↗
NASA NTRS1988

Fluoride salts as phase change materials for thermal energy storage in the temperature range 1000-1400 K

Eutectic compositions and congruently melting intermediate compounds in binary and ternary fluoride salt systems were characterized for potential use as latent heat of fusion phase change materials to store thermal energy in the temperature range 1000-1400 K. The melting points and eutectic compositions for many systems with published phase diagrams were experimentally verified and new eutectic compositions having melting points between 1000 and 1400 K were identified. Heats of fusion of several binary and ternary eutectics and congruently melting compounds were experimentally measured by differential scanning calorimetry. For a few systems in which heats of mixing in the melts have been measured, heats of fusion of the eutectics were calculated from thermodynamic considerations and good agreement was obtained between the measured and calculated values. Several combinations of salts with high heats of fusion per unit mass (greater than 0.7 kJ/g) have been identified for possible use as phase change materials in advanced solar dynamic space power applications.

Misra, Ajay K.↗
NASA NTRS1977

Intumescent-ablators as improved thermal protection materials

Nitroaromatic amine-based intumescent coatings were improved with regard to their thermal protection ability by adding endothermic decomposing fillers with endotherms at or near the exothermic reaction of the intumescent agent, since the effectiveness of the intumescent coatings without fillers is reduced by the exothermic behavior of the coatings during thermal activation. Fillers were dispersed directly in the base coating. Potassium fluoborate, ammonium fluoborate, zinc borate, and ammonium oxalate function as endothermic ablative materials at specific temperature regions, and also enhance the char formation during the intumescent process.

Sawko, P. M.↗
NASA NTRS2016

Cooling Rate Study of Nickel-Rich Material During Thermal Treatment and Quench

To investigate quench cracking that results from water quenching after heat treatment of binary and Ni-rich material, cooling rates of specimens were measured during quenching and hardness post-thermal treatment. For specific applications binary Ni-Ti is customarily thermally treated and quenched to attain desired mechanical properties and hardness. However, one problem emerging from this method is thermal cracking, either during the heat treatment process or during the specimen's application. This can result in material and equipment failure as well as financial losses. The objective of the study is to investigate the internal cooling rate of 60-NiTi during quenching and determine possible factors causing thermal cracking. Cubic (1 in.3) samples of both material were heat treated in air at 1000 deg C for 2 hrs and quenched in room temperature water using two methods: (1) dropped in the water and (2) agitated in the water. Hardness of the two fore-mentioned methods was measured post heat treatment. Results indicate that the quenching method had an effect on cooling rate during quenching but hardness was observed to be essentially the same through the thickness of the samples.

Thermal Crack↗
NASA NTRS1993

Flexible thermal protection materials for entry systems

Current programs addressed in aeroassist flight experiment are: (1) evaluation of thermal performance of advanced rigid and flexible insulations and reflective coating; (2) investigation of lighter than baseline materials; (3) investigation of rigid insulations which perform well; (4) study of flexible insulations which require ceramic coating; and (5) study of reflective coating effective at greater than 15 percent. In National Aerospace Plane (NASP), the programs addressed are: (1) high and low temperature insulations; and (2) attachment/standoff methodology critical which affects thermal performance.

Kourtides, Demetrius A.↗
NASA NTRS1976

Environmental charging of spacecraft-tests of thermal control materials for use on the global positioning system flight space vehicle. Part 2: Specimen 6 to 9

The NASA/USAF program on the Environmental Charging of Spacecraft Surfaces consists, in part, of experimental efforts directed toward evaluating the response of materials to the environmental charged particle flux. Samples of thermal blankets of the type to be used on the Global Positioning System Flight Space Vehicles were tested to determine their response to electron flux. The primary result observed was that no discharges were obtained with the quartz-fiber-fabric-covered multilayer insulation specimen. The taped aluminized polyester grounding system used on all specimens did not appear to grossly deteriorate with time; however, the specimens require specific external pressure to maintain constant grounding system resistance.

Stevens, N. J.↗
NASA NTRS1976

Environmental charging of spacecraft surfaces: Tests of thermal control materials for use on the global positioning system flight space vehicle. Part 1: Specimens 1 to 5

The NASA/USAF program on Environmental Charging of Spacecraft Surfaces consists of experimental efforts directed toward evaluating the response of materials to the environmental charged particle flux. Samples of thermal blankets and second surface mirrors of the type to be used on the Global Positioning System Flight Space Vehicle were tested to determine their response to electron flux. The primary result observed was that the ground connection of the metal layers of the blanket, as made by the baseline grounding technique using serrated washers and grommets, deteriorated with time at test. The discharges observed on the blankets were the glow type, not the 'lightning' strike observed on past specimens. Testing was performed at ambient laboratory temperatures.

Stevens, N. J.↗
NASA NTRS1997

New Low Thermal Conductivity Materials for Thermoelectric Applications

A low lattice themal conductivity is one of the conditions required to achieve high thermoelectric figures of merit. Several low themal conductivity materials were identified and developed over the past few years at JPL, including filled skutterudites and Zn (sub 4) Sb (sub 3) - based materials.

Thermal Conductivity phonon scattering themoelectr↗
NASA NTRS1996

Surface Catalytic Efficiency of Advanced Carbon Carbon Candidate Thermal Protection Materials for SSTO Vehicles

The catalytic efficiency (atom recombination coefficients) for advanced ceramic thermal protection systems was calculated using arc-jet data. Coefficients for both oxygen and nitrogen atom recombination on the surfaces of these systems were obtained to temperatures of 1650 K. Optical and chemical stability of the candidate systems to the high energy hypersonic flow was also demonstrated during these tests.

Stewart, David A.↗
NASA NTRS1998

Results of Two-Stage Light-Gas Gun Development Efforts and Hypervelocity Impact Tests of Advanced Thermal Protection Materials

Gun development efforts to increase the launching capabilities of the NASA Ames 0.5-inch two-stage light-gas gun have been investigated. A gun performance simulation code was used to guide initial parametric variations and hardware modifications, in order to increase the projectile impact velocity capability to 8 km/s, while maintaining acceptable levels of gun barrel erosion and gun component stresses. Concurrent with this facility development effort, a hypervelocity impact testing series in support of the X-33/RLV program was performed in collaboration with Rockwell International. Specifically, advanced thermal protection system materials were impacted with aluminum spheres to simulate impacts with on-orbit space debris. Materials tested included AETB-8, AETB-12, AETB-20, and SIRCA-25 tiles, tailorable advanced blanket insulation (TABI), and high temperature AFRSI (HTA). The ballistic limit for several Thermal Protection System (TPS) configurations was investigated to determine particle sizes which cause threshold TPS/structure penetration. Crater depth in tiles was measured as a function of impact particle size. The relationship between coating type and crater morphology was also explored. Data obtained during this test series was used to perform a preliminary analysis of the risks to a typical orbital vehicle from the meteoroid and space debris environment.

Cornelison, C. J.↗
NASA NTRSDate not supplied

Stochastic Reconstruction of Thermal Protection Material Properties from Arc-Jet Experiments

Material response models are used to assess reliability using variances in the bond-line temperature predictions based on uncertainties in trajectory, aerothermal environment, and material properties. A key deficiency in the current approach is that input uncertainties are too often subjective, empirical, or ad-hoc, and are not rigorously linked to the arc-jet test data used to develop the TPS material model. While materials such as PICA are well understood, future missions may require more novel materials such as HEEET where unknown uncertainties have real consequences on the ability to assess reliability. A quantifiable estimate of reliability requires an iterative methodology where the parameters driving the variance in bond-line temperature (for example) are systematically identified. A test campaign to collect data or develop new models can then be identified to reduce those input uncertainties. A Bayesian inference loop defines these connections mathematically, i.e., prior knowledge about uncertainty is updated based on observation. While these concepts are well known (and often applied intuitively in a non-rigorous approach), only recent advances in reduced-order modelling have made them computationally viable methods for engineering. By replacing deterministic inverse methods with stochastic approaches, the hope is new materials proposed for future missions can more rapidly be developed with a greater understanding of the TPS material reliability. Two additional steps for the analysis of arc jet test data are discussed. The first is ability to construct a reduced-order model using material response simulations (Icarus/US3D) of the arc-jet test articles, and the second is the inclusion of this surrogate model in the Bayesian inversion process. Both capabilities will be demonstrated using prior PICA arc-jet test data. The quality of a surrogate model will be investigated and the variances on the calibrated material properties will be compared to our current understanding of the PICA material model.

Material response↗
NASA NTRS2005

High-Temperature Structures, Adhesives, and Advanced Thermal Protection Materials for Next-Generation Aeroshell Design

The next generation of planetary exploration vehicles will rely heavily on robust aero-assist technologies, especially those that include aerocapture. This paper provides an overview of an ongoing development program, led by NASA Langley Research Center (LaRC) and aimed at introducing high-temperature structures, adhesives, and advanced thermal protection system (TPS) materials into the aeroshell design process. The purpose of this work is to demonstrate TPS materials that can withstand the higher heating rates of NASA's next generation planetary missions, and to validate high-temperature structures and adhesives that can reduce required TPS thickness and total aeroshell mass, thus allowing for larger science payloads. The effort described consists of parallel work in several advanced aeroshell technology areas. The areas of work include high-temperature adhesives, high-temperature composite materials, advanced ablator (TPS) materials, sub-scale demonstration test articles, and aeroshell modeling and analysis. The status of screening test results for a broad selection of available higher-temperature adhesives is presented. It appears that at least one (and perhaps a few) adhesives have working temperatures ranging from 315-400 C (600-750 F), and are suitable for TPS-to-structure bondline temperatures that are significantly above the traditional allowable of 250 C (482 F). The status of mechanical testing of advanced high-temperature composite materials is also summarized. To date, these tests indicate the potential for good material performance at temperatures of at least 600 F. Application of these materials and adhesives to aeroshell systems that incorporate advanced TPS materials may reduce aeroshell TPS mass by 15% - 30%. A brief outline is given of work scheduled for completion in 2006 that will include fabrication and testing of large panels and subscale aeroshell test articles at the Solar-Tower Test Facility located at Kirtland AFB and operated by Sandia National Laboratories. These tests are designed to validate aeroshell manufacturability using advanced material systems, and to demonstrate the maintenance of bondline integrity at realistically high temperatures and heating rates. Finally, a status is given of ongoing aeroshell modeling and analysis efforts which will be used to correlate with experimental testing, and to provide a reliable means of extrapolating to performance under actual flight conditions. The modeling and analysis effort includes a parallel series of experimental tests to determine TSP thermal expansion and other mechanical properties which are required for input to the analysis models.

Collins, Timothy J.↗