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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Thermal protection system trade studies on ablators and reuseable surface insulation

Analytical trade studies are presented that consider passive TPS configurations using the following material categories: (1) reuseable surface insulation - surface-coated rigidized ceramic fiber; (2) low density charring ablators; and (3) carbon-carbon and high density ablators for leading edge areas. Emphasized are effects on TPS weight by variations in entry trajectories and material thermal characteristics.

Strouhal, G.↗
NASA NTRS1972

Status of reusable surface insulation thermal protection system technology programs

The development of three low-density rigidized insulation materials for the shuttle TPS application is reported. These materials consist of one high purity silica system and two systems based on mullite, an aluminum silicate. Both systems consist of fibers joined together with appropriate binders to obtain a rigidized insulation composite. Both material systems require the application of a glassy coating to provide a wear resistant, high emittance surface and to prevent the absorption of water by the fiber matrix. The technology program has addressed the development of water impervious coatings, methods of assembling the materials in design concepts while minimizing the thermal stress in the insulation, achieving compatibility between the RSI material and the structural system, and test evaluations to demonstrate the feasibility of the surface insulation concept.

Greenshields, D. H.↗
NASA NTRS1972

Refurbishment cost study of the thermal protection system of a space shuttle vehicle, phase 2

Labor costs and techniques associated with the refurbishment of representative TPS and their attach concepts suitable for space shuttle application have been identified on the basis of experimental tests. Ablative and reusable surface insulation TPS configurations were designed, fabricated, and tested on a full-scale mockup. The TPS attachment methods investigated included pi-strap, multiple mechanical fasteners, key/keyway, and direct bond concepts. Techniques for performing installation, inspection, repair and replacement of TPS components were studied by examining a variety of shop procedures. Major problem areas associated with these procedures and the designs to which they were applied were analyzed for several significant parameters such as handling, gaskets between joints, repair techniques, ablator plugs, etc. Results of time and motion studies of specific maintenance tasks, simulating operational procedures, were obtained. Using these data, refurbishment labor cost projections were generated for a representative Space Shuttle orbiter.

Haas, D. W.↗
NASA NTRS1972

Advanced extravehicular protective systems for shuttle, space station, lunar base and Mars missions.

Advances in extravehicular life support system technology will directly influence future space mission reliability and maintainability considerations. To identify required new technology areas, an appraisal of advanced portable life support system and subsystem concepts was conducted. Emphasis was placed on thermal control and combined CO2 control/O2 supply subsystems for both primary and emergency systems. A description of study methodology, concept evaluation techniques, specification requirements, and selected subsystems and systems are presented. New technology recommendations encompassing thermal control, CO2 control and O2 supply subsystems are also contained herein.

Heimlich, P. F.↗
NASA NTRS1972

Development of dispersion-strengthened Ni-Cr-ThO2 alloys for the space shuttle thermal protection system.

An improved manufacturing process has been developed for TD-NiCr that provides sheet of improved quality, better gage control, and reproducible properties. A standard manufacturing process has been developed for the alternate alloy, DS-NiCr, produced by pack-chromizing Ni-2ThO2 sheet. Extension of forming and joining technology for TD-NiCr is in process. Formability criteria are being established for basic sheet forming processes related to the manufacture of Shuttle TPS panels. They include brake forming, corrugation forming, joggling, dimpling, and beading. Joining processes applicable to TPS panels are being optimized with emphasis on establishment of joint efficiencies. Resistance spot welding (fusion and solid state), resistance seam welding, solid-state diffusion welding, and brazing are included in the joining programs. Development of improved manufacturing technology for TD-NiCr fasteners is also being accomplished. Mechanical and physical properties of TD-NiCr are being characterized to provide design-allowable data.

Blankenship, C. P.↗
NASA NTRS1972

High temperature insulation materials for reradiative thermal protection systems

Results are presented of a two year program to evaluate packaged thermal insulations for use under a metallic radiative TPS of a shuttle orbiter vehicle. Evaluations demonstrated their survival for up to 100 mission reuse cycles under shuttle acoustic and thermal loads with peak temperatures of 1000 F, 1800 F, 2000 F, 2200 F and 2500 F. The specimens were composed of low density refractory fiber felts, packaged in thin gage metal foils. In addition, studies were conducted on the venting requirements of the packages, salt spray resistance of the metal foils, and the thermal conductivity of many of the insulations as a function of temperature and ambient air pressure. Data is also presented on the radiant energy transport through insulations, and back-scattering coefficients were experimentally determined as a function of source temperature.

Hughes, T. A.↗
NASA NTRS1972

Thermal elastoplastic structural analysis of non-metallic thermal protection systems

An incremental theory and numerical procedure to analyze a three-dimensional thermoelastoplastic structure subjected to high temperature, surface heat flux, and volume heat supply as well as mechanical loadings are presented. Heat conduction equations and equilibrium equations are derived by assuming a specific form of incremental free energy, entropy, stresses and heat flux together with the first and second laws of thermodynamics, von Mises yield criteria and Prandtl-Reuss flow rule. The finite element discretization using the linear isotropic three-dimensional element for the space domain and a difference operator corresponding to a linear variation of temperature within a small time increment for the time domain lead to systematic solutions of temperature distribution and displacement and stress fields. Various boundary conditions such as insulated surfaces and convection through uninsulated surface can be easily treated. To demonstrate effectiveness of the present formulation a number of example problems are presented.

Chung, T. J.↗
NASA NTRS1971

Degradation and reuse of radiative thermal protection system materials for the space shuttle

Three silicide coated columbium alloys and two cobalt alloys were subjected to identical simulated reentry profiling exposures in both static (controlled vacuum leak) and dynamic (hypersonic plasma shear) environments. Primary emphasis in the columbium alloy evaluation was on the Cb752 and C129Y alloys with a lesser amount on FS85. Commercial silicide coatings of the R512E and VH109 formulations were used. The coated specimens were intentionally defected to provide the types of coating flaws that are expected in service. Temperatures were profiled up to peak temperatures of either 2350 F or 2500 F for 15 minutes in each cycle.

Bartlett, E. S.↗
NASA NTRS1973

Design of thermal protection system for 8 foot HTST combustor

The combustor in the 8-foot high temperature structures tunnel at the NASA-Langley Research Center has encountered cracking over a period of 50-250 tunnel tests within a limited range of the required operating envelope. A program was conducted which analyzed the failed combustor liner hardware and determined that the mechanism of failure was vibratory fatigue. A vibration damper system using wave springs located axially between the liner T-bar and the liner support was designed as an intermediate solution to extend the life of the current two-pass regenerative air-cooled liner. The effects of liner wall thickness, cooling air passage height, stiffener ring geometry, reflective coatings, and liner material selection were investigated for these designs. Preliminary layout design arrangements including the external water-cooling system requirements, weight estimates, installation requirements and preliminary estimates of manufacturing costs were prepared for the most promissing configurations. A state-of-the-art review of thermal barrier coatings and an evaluation of reflective coatings for the gasside surface of air-cooled liners are included.

Moskowitz, S.↗
NASA NTRS1973

Development of high temperature silicone adhesive formulations for thermal protection system applications

Trade-off studies and screening evaluations were made of commercial polymers and silicone foam sheet stock. A low modulus, low density 0.26 gm/cc modification was developed of the GE-RESD PD-200 system based upon GE RTV-560 silicone polymer. The bond system modification was initially characterized for mechanical and thermal properties, evaluated for application methods, and its capability demonstrated as a strain arrestor bond system.

Hockridge, R. R.↗
NASA NTRS1973

Environmental testing of REI-Mullite thermal protection system for the space shuttle orbiter

Tests conducted to evaluate performances in the natural environments of salt spray, humidity, rain, vacuum, and cryogenic temperatures have shown the ceramic mullite fiber is completely compatible and that these environments have no adverse effects on subsequent mission performance. Rain erosion testing has indicated a damage threshold that must be accounted for in the final design. Tests conducted to evaluate the performance of ceramic mullite fiber to induced acoustic, re-entry, and structural load environments again have shown complete capability to fulfill mission environments. Although minor cracking of the sidewall coating was seen to occur throughout the induced environment test program, sidewall designs configured to provide increased flexibility have been successfully tested.

Gluck, R.↗
NASA NTRS1973

Reusable surface insulation thermal protection systems test evaluation status

Changes in coating morphology of mullite, silica, and ceramic mullite fiber at two heating rates are described followed by a discussion of the changes in surface chemistry that occur during convective heating tests. Subsequently, the surface chemistry changes observed are compared to similar data obtained from radiantly heated coatings and the significance of the difference between the results is discussed. Finally, the changes in chemistry of the coatings in cross section before and after convectively heated cyclic testing are discussed and the significance of surface chemistry changes are described. Results indicate that the thermal conductivity of mullite surface insulation is higher than that of silica insulation, based on thermal response data. Acoustic excitation of cracked silica tiles does not lead to catastrophic failure such as spallation or tile loss. Cracks in mullite material after thermal exposure lead to fracturing of the coating and surface insulation material after acoustic excitation.

Strouhal, G.↗
NASA NTRS1973

Catalysis study for space shuttle vehicle thermal protection systems

Experimental results on the problem of reducing aerodynamic heating on space shuttle orbiter surfaces are presented. Data include: (1) development of a laboratory flow reactor technique for measuring gamma sub O and gamma sub N on candidate materials at surfaces, T sub w, in the nominal range 1000 to 2000, (2) measurements of gamma sub O and gamma sub N above 1000 K for both the glass coating of a reusable surface insulation material and the siliconized surface of a reinforced pyrolyzed plastic material, (3) measurement of the ablation behavior of the coated RPP material at T sub w is greater than or equal to 2150 K, (4) X-ray photoelectron spectral studies of the chemical constituents on these surfaces before and after dissociated gas exposure, (5) scanning electron micrograph examination of as-received and reacted specimens, and (6) development and exploitation of a method of predicting the aerodynamic heating consquences of these gamma sub O(T sub w) and gamma sub N(T sub w) measurements for critical locations on a radiation cooled orbiter vehicle.

Breen, J.↗
NASA NTRS1973

Evaluation of coated columbium alloy heat shields for space shuttle thermal protection system application. Volume 2, phase 2: Subsize heat shield and small size TPS evaluation

Initially a trade study was conducted of seven heat shield configurations. These were evaluated for structural reliability, fabricability, weight, inspectability, and refurbishability. Two concepts, a tee-stiffened and an open corrugation, were selected as offering the most potential for system success. Fourteen subsize heat shields of a full scale section were fabricated from C-129Y and Cb-752 and silicide coated with R-512E. These subsize panels were subjected to a simulated flight profile representing temperature, local surface pressures, and applied pressure differential loads. All corrugated panels of both alloys sustained 100 cycles without structural or coating failure. All Cb-752/R-512E panels performed well with one panel being successfully repaired after 66 cycles and completing 100 cycles. As a result of this evaluating the Cb-752/R-512E system was selected for hardware application during the subsequent phases. In addition, the tee-stiffened configuration was selected for further development and application in Phase III. This selection was based on an overall assessment of relative weight, cost, and structural performance of the tee-stiffened and open corrugation TPS.

Black, W. E.↗