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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Comparison of visualized turbine endwall secondary flows and measured heat transfer patterns

Various flow visualization techniques were used to define the seondary flows near the endwall in a large heat transfer data. A comparison of the visualized flow patterns and the measured Stanton number distribution was made for cases where the inlet Reynolds number and exit Mach number were matched. Flows were visualized by using neutrally buoyant helium-filled soap bubbles, by using smoke from oil soaked cigars, and by a few techniques using permanent marker pen ink dots and synthetic wintergreen oil. Details of the horseshoe vortex and secondary flows can be directly compared with heat transfer distribution. Near the cascade entrance there is an obvious correlation between the two sets of data, but well into the passage the effect of secondary flow is not as obvious. Previously announced in STAR as N83-14435

Gaugler, R. E.↗
NASA NTRS1984

Aerothermodynamic environment and thermal protection for a Titan aerocapture vehicle

This paper presents thermal protection system (TPS) requirements for a potential Titan aerocapture vehicle. Shock-layer solutions are obtained for a nominal trajectory through the current Titan model atmosphere. Fully laminar and fully turbulent solutions are presented along the blunted fore-cone in the windward symmetry plane of a bent-biconic vehicle. Using these solutions to define the aerothermodynamic environment, transient material-response solutions are obtained for a Galileo-type TPS with a carbon-phenolic ablator heat shield. Shock-layer results indicate that turbulent flow is the more realistic flow condition. They also show that the lengthy aerocapture heating pulse is dominated by convective heating. The TPS results show that the required insulation thickness is uniformly about 4 cm along the fore-cone because of the long heat-soak period. The total heat-shield thickness is 6.4 cm at the stagnation point, and 4.7 cm near the end of the fore-cone. These TPS requirements are greater than those presented in a previous Titan aerocapture study.

Green, M. J.↗
NASA NTRS1984

Topological reaction rate measurements related to scuffing

A ball-on-plate (both consisting of hardened M-50 steel) sliding elastohydrodynamic contact was run with trimethylolpropane triheptanoate (TMPTH) with and without tricresyl phosphate (TCP). The contact area of the plate was optically profiled with a phase-locked interference microscope (PLIM) both before and after exposure to alcoholic hydrochloric acid. As scuffing was approached, the profile within the contact region changed more rapidly after the acid treatment; after scuffing, it assumed a constant high value. A metallurgical phase found in the scuff mark was apparently responsible for the high reactivity. The microscopic profile changes (sensitivity, + or - 3 nm (+ or - A) in depth) involved primarily the small asperities (radius, 3 microns); the larger ones were unaffected. Soaking the steel in TCP smoothed the fine structure of the surface profile but increased its reactivity toward alcoholic hydrochloric acid before sliding was started. Thus it would appear that PLIM examination could be used for screening potentially scuff-resistant materials.

Lauer, J. L.↗
NASA NTRS1986

Development of flight ready fifty-micron-thick silicon solar cell array module technology

The development of ultrathin silicon solar cell array modules from initial design to flight testing is discussed. Three 80-cell modules were subjected to the thermal soak test, the LEO thermal cycle test, and the solar array flight experiment, and six 48-cell welded modules were evaluated in the geosynchronous orbit thermal cycle test. It is observed that the electrical performance of the modules was not affected by the different environmental conditions. The automatic assembly of the cell modules, in particular the welding and solar cell glassing operation, is described. The specific power capabilities of Kapton, Kapton-Kevlar-Kapton, Kapton-graphite-Kapton, and Kapton-graphite-aluminum honeycomb-graphite solar array designs are assessed.

Patterson, R. E.↗
NASA NTRS1985

Development of heat flux sensors for turbine airfoils

The objectives of this program are to develop heat flux sensors suitable for installation in hot section airfoils of advanced aircraft turbine engines and to experimentally verify the operation of these heat flux sensors in a cylinder in a cross flow experiment. Embedded thermocouple and Gardon gauge sensors were developed and fabricated into both blades and vanes. These were then calibrated using a quartz lamp bank heat source and finally subjected to thermal cycle and thermal soak testing. These sensors were also fabricated into cylindrical test pieces and tested in a burner exhaust to verify heat flux measurements produced by these sensors. The results of the cylinder in cross flow tests are given.

Atkinson, William H.↗
NASA NTRS1988

Effects of moisture, elevated temperature, and fatigue loading on the behavior of graphite/epoxy buffer strip panels with center cracks

The effects of fatigue loading combined with moisture and heat on the behavior of graphite epoxy panels with either Kevlar-49 or S-glass buffer strips were studied. Buffer strip panels, that had a slit in the center to represent damage, were moisture conditioned or heated, fatigue loaded, and then tested in tension to measure their residual strength. The buffer strips were parallel to the loading direction and were made by replacing narrow strips of the 0 deg graphite plies with Kevlar-49 epoxy or S-glass epoxy on a 1-for-1 basis. The panels were subjected to a fatigue loading spectrum. One group of panels was preconditioned by soaking in 60 C water to produce a 1 percent weight gain then tested at room temperature. One group was heated to 82 C during the fatigue loading. Another group was moisture conditioned and then tested at 82 C. The residual strengths of the buffer panels were not highly affected by the fatigue loading, the number of repetitions of the loading spectrum, or the maximum strain level. The moisture conditioning reduced the residual strengths of the S-glass buffer strip panel by 10 to 15 percent below the ambient results. The moisture conditioning did not have a large effect on the Kevlar-49 panels.

Bigelow, C. A.↗
NASA NTRS1987

Thermal properties and effects for Li/BCX (thionyl chloride) cells

New NASA requirements for the screening of lithium cells for space applications involve thermal soaks at elevated temperatures (149 C). The currently qualified Li/BCX cells and three design modifications have been evaluated showing that a design incorporating a shortened electrode stack met this test condition while continuing to satisfy the performance and safety requirements for cells used on NASA manned space vehicles. Information was also developed to show that measured heat capacities for the BCX D size cells correlated well with the heat generated from cells discharged in an insulated environment. Calculated heat capacities based on the amounts and types of materials in a cell were low compared to these values. This information provides the basis for the design of battery packs in the highly insulating environment of outer space.

Takeuchi, E. S.↗
NASA NTRS1988

Iodine sorption study on the proposed use of Viton A in a shuttle galley water accumulator

The installation of a Viton A accumulator in the Shuttle galley has been proposed to prevent overpressurization of the hot water supply system. A laboratory study has been conducted to determine if there would be any interaction between the Viton A material and the iodine used to disinfect the water. Coupons of Viton A were exposed for 24 hours to aqueous iodine solutions similar in quality to the Shuttle's potable water. Changes in the iodine residual were monitored to determine the rate of iodine sorption by the coupon. Total organic carbon (TOC) was monitored to determine the rate of desorption of organic materials from the Viton A. The same coupons were then soaked in reagent-grade water for 24 hours, and iodine was monitored to determine the rate of iodine desorption. The coupons were again exposed to iodine solutions for 24 hours and iodine and TOC were monitored. No significant change in the iodine sorption rate was detected between the first and second exposures. A triangle taste test indicated at a 1 percent confidence level that the water exposed to Viton A had a different taste which was less acceptable to the panelists.

Gibbons, Randall E.↗
NASA NTRS1988

A study of thermal transitions in a new semicrystalline thermoplastic polyimide

A polyimide derive from 4,4'-isophthaloyl diphthalic anhydride (IDPA) and 1,3-bis (4-aminophenoxy 4'-benzoyl) benzene (1,3-BABB) having semicrystalline behavior was prepared and characterized by differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). Thus a poly(amic acid) film cured in air for one hour each at 100 and 200 C displayed an endotherm at 286 C, followed by a crystallization exotherm at 317 C, and a second melting transition at 350 C. The 286 C melting point appeared to result from earlier solvent-induced crystallization. Films cast from DMAc, air dried, and soaked in methylene chloride could not be induced into semicrystallinity. The fully cured polyimide has a Tg of 216 C. Films heated to temperatures as high as 100 C for one hour in air were transparent and light yellow in color. Those films heated to or above 125 C were translucent. Polarized light microscopy revealed the presence of spherulites 608 micrometers in diameter in a sample cured to 275 C in air. Two film samples, one cured to 275 and the other to 325 C, were evaluated for tensile and ultimate strength, modulus, and percent elongation at 25 and 200 C. These values remained essentially constant at each test temperature.

Pratt, J. Richard↗
NASA NTRS1989

Advanced APS impacts on vehicle payloads

Advanced auxiliary propulsion system (APS) technology has the potential to both, increase the payload capability of earth-to-orbit (ETO) vehicles by reducing APS propellant mass, and simplify ground operations and logistics by reducing the number of fluids on the vehicle and eliminating toxic, corrosive propellants. The impact of integrated cryogenic APS on vehicle payloads is addressed. In this system, launch propulsion system residuals are scavenged from integral launch propulsion tanks for use in the APS. Sufficient propellant is preloaded into the APS to return to earth with margin and noncomplete scavenging assumed. No propellant conditioning is required by the APS, but ambient heat soak is accommodated. High temperature rocket materials enable the use of the unconditioned hydrogen/oxygen in the APS and are estimated to give APS rockets specific impulse of up to about 444 sec. The payload benefits are quantified and compared with an uprated monomethylhydrazine/nitrogen tetroxide system in a conservative fashion, by assuming a 25.5 percent weight growth for the hydrogen/oxygen system and a 0 percent weight growth for the uprated system. The combination of scavenging and high performance gives payload impacts which are highly mission specific. A payload benefit of 861 kg (1898 lbm) was estimated for a Space Station Freedom rendezvous mission and 2099 kg (4626 lbm) for a sortie mission, with payload impacts varying with the amount of launch propulsion residual propellants. Missions without liquid propellant scavenging were estimated to have payload penalties, however, operational benefits were still possible.

Schneider, Steven J.↗
NASA NTRS1988

Characterization of cobalt(II) chloride-modified condensation polyimide films

The effect of solvent extraction on the properties of cobalt(II) chloride-modified polyimide films was investigated. Solvent-cast films were prepared from solutions of cobalt chloride in poly(amide acid)/N,N-dimethylacetamide (DMAc) and were subsequently dried and cured in static air, forced air, or inert gas ovens with controlled humidity. The films were extracted by either of the three processes (1) soaking in a tray with distilled water at room temperature, (2) soxhlett extraction with distilled water, or (3) soxhell extraction with DMAc. Extraction with DMAc was found to remove both cobalt and chlorine from the films and to slightly increase bulk thermal stability and both surface resistivity and electrical resistivity.

Rancourt, J. D.↗
NASA NTRS1988

Growth and characterization of large YBa2Cu3O(7-x) single crystals

Centimeter-sized crystal plates of YBa2Cu3O(7-x) have been obtained using a bulk composition and method described by Schneemeyer at al. (1987) modified for growth in a pure oxygen atmosphere. A porous MgO crucible and long soak time promote large crystals. Mg was not detectable in the crystals. Electron microbeam analysis using a 60 A monochromator crystal for the oxygen determination gave the composition Y(1.05)Ba(2.02)Cu(2.94)O(6.52 + or - 0.06). As-grown crystals from the melt surface exhibit a fairly sharp Tc with zero resistance at 80 K, and show complex twinning and crack patterns. Optical micrographs of a lightly polished surface normal to the c-axis of a 3-mm crystal delineate twinning and fine scale microcracking; this crystal surface now has a zero resistance at 68 K. Microhardness measurements and microfracture observations indicate intrinsic properties that may inhibit or impede large scale manufacture of electronic ceramics.

Keester, Kenneth L.↗
NASA NTRS1988

Improved Li/BCX (thionyl chloride) cells for space applications

New NASA requirements for the screening of lithium cells for space applications involve thermal soaks at elevated temperatures (149 C). The BCX DD and C size cells have been redesigned to pass this test with only marginal losses in capacity as was done previously for the D cells. In addition, the pressure increases in cells subjected to this high temperature environment have been characterized showing that the earlier designs failed this exposure due to lack of void volume. An improve BCX chemistry has been demonstrated which significantly improves voltage delay problems encountered after partial discharge and storage of the cells.

Clark, W. D. K.↗
NASA NTRS1989

Development and characterization of PdCr temperature-compensated wire resistance strain gage

A temperature-compensated resistance static strain gage with potential to be used to 600 C was recently developed. Gages were fabricated from specially developed palladium-13 w/o chromium (Pd-13Cr) wire and platinum (Pt) compensator. When bonded to high temperature Hastelloy X, the apparent strain from room temperature to 600 C was within 400 microstrain for gages with no preheat treatment and within 3500 microstrain for gages with 16 hours prestabilization at 640 C. The apparent strain versus temperature relationship of stabilized PdCr gages were repeatable with the reproducibility within 100 microstrain during three thermal cycles to 600 C and an 11 hours soak at 600 C. The gage fabrication, construction and installation is described. Also, the coating system used for this compensated resistance strain gage is explained. The electrical properties of the strain sensing element and main characteristics of the compensated gage including apparent strain, drift and reproducibility are discussed.

Lei, Jih-Fen↗
NASA NTRS1989

Advanced APS Impacts on Vehicle Payloads

Advanced auxiliary propulsion system (APS) technology has the potential to both, increase the payload capability of earth-to-orbit (ETO) vehicles by reducing APS propellant mass, and simplify ground operations and logistics by reducing the number of fluids on the vehicle and eliminating toxic, corrosive propellants. The impact of integrated cryogenic APS on vehicle payloads is addressed. In this system, launch propulsion system residuals are scavenged from integral launch propulsion tanks for use in the APS. Sufficient propellant is preloaded into the APS to return to earth with margin and noncomplete scavenging assumed. No propellant conditioning is required by the APS, but ambient heat soak is accommodated. High temperature rocket materials enable the use of the unconditioned hydrogen/oxygen in the APS and are estimated to give APS rockets specific impulse of up to about 444 sec. The payload benefits are quantified and compared with an uprated monomethyl hydrazine/nitrogen tetroxide system in a conservative fashion, by assuming a 25.5 percent weight growth for the hydrogen/oxygen system and a 0 percent weight growth for the uprated system. The combination and scavenging and high performance gives payload impacts which are highly mission specific. A payload benefit of 861 kg (1898 lbm) was estimated for a Space Station Freedom rendezvous mission and 2099 kg (4626 lbm) for a sortie mission, with payload impacts varying with the amount of launch propulsion residual propellants. Missions without liquid propellant scavenging were estimated to have payload penalties, however, operational benefits were still possible.

Schneider, Steven J.↗
NASA NTRS1990

Production of superconductor/carbon bicomponent fibers

Certain materials are unable to be drawn or spun into fiber form due to their improper melting characteristics or brittleness. However, fibrous samples of such materials are often necessary for the fabrication of intricate shapes and composites. In response to this problem, a unique process, referred to as the piggyback process, was developed to prepare fibrous samples of a variety of nonspinnable ceramics. In this technique, specially produced C-shaped carbon fibers serve as micromolds to hold the desired materials prior to sintering. Depending on the sintering atmosphere used, bicomponent or single component fibers result. While much has been demonstrated worldwide concerning the YBa2Cu3O(7-x) superconductor, fabrication into unique forms has proven quite difficult. However, a variety of intricate shapes are necessary for rapid commercialization of the superconducting materials. The potential for producing fibrous samples of the YBa2Cu3O(7-x) compound by the piggyback process is being investigated. Various organic and acrylic materials were investigated to determine suspending ability, reactivity with the YBa2Cu3O(7-x) compound during long term storage, and burn out characteristics. While many questions were answered with respect to the interfacial reactions between YBa2Cu3O(7-x) and carbon, much work is still necessary to improve the quality of the sintered material if the fibers produced are to be incorporated into useful composites or cables. Additional research is necessary to evaluate quality of the barrier layer during long soakings at the peak temperature; adjust the firing schedule to avoid microcracking and improve densification; and increase the solids loading in the superconductive suspension to decrease porosity.

Wise, S. A.↗
NASA NTRS1991

Investigation of welding and brazing of molybdenum and TZM alloy tubes

This effort involved investigating the welding and brazing techniques of molybdenum tubes to be used as cartridges in the crystal growth cartridge. Information is given in the form of charts and photomicrographs. It was found that the recrystallization temperature of molybdenum can be increased by alloying it with 0.5 percent titanium and 0.1 percent zirconium. Recrystallization temperatures for this alloy, known as TZM, become significant around 2500 F. A series of microhardness tests were run on samples of virgin and heat soaked TZM. The test results are given in tabular form. It was concluded that powder metallurgy TZM may be an acceptable cartridge material.

Lundblad, Wayne E.↗
NASA NTRS1991

Effects of water on the strength of Zerodur

An experimental design matrix was constructed to determine the effects of time and temperature water soak on the strength of Zerodur glass-ceramic. It was found that strength does increase in a nonlinear manner which is consistent with existing theories of crack tip blunting and residual stress reduction.

Tucker, Dennis S.↗