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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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13 records
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NASA NTRS1977

Fracture control of H-O engine components

An investigation was made to obtain the material characterization and fatigue crack propagation data necessary to establish the salient characteristics of a Ti-6Al-2.5Sn(ELI) alloy fuel pump impeller to be used in a cryogenic service environment. Testing variables considered were: coupon orientation, frequency, load range ratio, and temperature. Data analysis correlated crack propagation data from conventional laboratory coupons with data from a parallel sided rotating disk used to model rotor stresses. Four major design recommendations when bore regions of fuel pump impellers to be operated in cryogenic environments are to be relatively highly stressed are discussed.

Ryder, J. T.↗
NASA NTRS1994

The Twenty-Fifth Lunar and Planetary Science Conference. Part 2: H-O

Various papers on lunar and planetary science are presented, covering such topics as: planetary geology, lunar geology, meteorites, shock loads, cometary collisions, planetary mapping, planetary atmospheres, chondrites, chondrules, planetary surfaces, impact craters, lava flow, achondrites, geochemistry, stratigraphy, micrometeorites, tectonics, mineralogy, petrology, geomorphology, and volcanology.

Source record↗
NASA NTRS2002

C-H Hot Bands in the Near-IR Emission Spectra of Leonids

The reported infrared (IR) emission spectra from 1999 Leonid fireballs show a 3.4 micron C-H emission band and unidentified bands at longer wavelengths. Upon atmospheric entry, the Leonid meteorites were flash-heated to temperatures around 2400K, which would destroy any organics on the surface of the meteorite grains. We propose that the nu(sub )CH emission band in the Leonid emission spectra arises from matrix-embedded C(sub n)-H-O entities that are protected from instant pyrolysis. Our model is based on IR absorption nu(sub )CH bands, which we observed in laboratory-grown MgO and natural olivine single crystals, where they arise from C(sub n)-H-O units imbedded in the mineral matrix, indicative of aliphatic -CH2- and -CH3 organics. Instead of being pyrolyzed, the C(sub n)-H-O entities in the Leonid trails become vibrationally excited to higher levels n = 1, 2, 3 etc. During de-excitation they emit at 3.4 microns, due to the (0 => 1) transition, and at longer wavelengths, due to hot bands. As a first step toward verifying this hypothesis we measured the C-H vibrational manifold of hexane (C6H14). The calculated positions of the (2 => l ) , (3 => 2), and possibly (4 => 3) hot bands agree with the Leonid emission bands at 3.5, 3.8 and 4.l microns.

Freund, F. T.↗
NASA NTRS1982

On the use of a global hydrogen-air combustion model in the calculation of turbulent reacting flows

A two-step global model describing the combustion of hydrogen in air at one atmosphere pressure is developed by comparing the temperature histories obtained from a 28-reaction H-O mechanism. Using criteria discussed herein, good agreement is obtained in the range of initial mixture temperatures from 1000K to 2000K and in the range of equivalence ratios from 0.2 to 2.0. The two-step global model is compared with the results obtained using an eight-step, H-O reaction mechanism in a computer program describing the turbulent diffusion of hydrogen in supersonic, axisymmetric and two-dimensional reacting flows. Comparisons of profiles of temperature, fuel mass flux, and pitot pressure are presented. The global model is judged to be adequate in flows which are not dominated by long ignition delay times.

Rogers, R. C.↗
NASA NTRS1991

Technology readiness assessment of advanced space engine integrated controls and health monitoring

An evaluation is given for an integrated control and health-monitoring (ICHM) system that is designed to be used with hydrogen-oxygen rocket engines. The minimum required ICHM functions, system elements, technology readiness, and system cost are assessed for a system which permits the operation of H-O engines that are space-based, reusable, and descent-throttleable. Only the advanced sensors and some engine-dependent software are not found to be ready for applications to laboratory demonstration. Other systems related to the minimum functions are more developed, bringing the total system readiness to the conceptual design stage. Based on the evaluation of the H-O ICHM, it is estimated that the minimum system requirements for demonstration on an engine system testbed will require an investment of 30-45 million dollars over 6 years.

Millis, Marc G.↗
NASA NTRS1991

Technology readiness assessment of advanced space engine integrated controls and health monitoring

An evaluation is given for an integrated control and health monitoring system (ICHM) system that is designed to be used with hydrogen-oxygen rocket engines. The minimum required ICHM functions, system elements, technology readiness, and system cost are assessed for a system which permits the operation of H-O engines that are space-based, reusable, and descent throttleable. Based on the evaluation of the H-O ICHM, it is estimated that the minimum system requirements for demonstration on an engine system testbed will require an investment of 30 to 45 million dollars over six years.

Millis, Marc G.↗
NASA NTRS1968

Lunar power systems - A long view.

Lunar surface power plants, considering weight constraint for various systems using nuclear power, solar cell/fuel cells and H-O reactant regeneration

Schulman, F.↗
NASA NTRS1972

Aerodynamic stability and drag characteristics of a parallel burn/SRM ascent configuration at Mach numbers from 0.6 to 4.96

Experimental aerodynamic investigations were conducted in the NASA/MSFC 14-inch trisonic wind tunnel during March 1972 on a .003366 scale model of a solid rocket motor version of the space shuttle ascent configuration. The configuration consisted of a parallel burn solid rocket motor booster on an external H-O centerline tank orbiter. Six component aerodynamic force and moment date were recorded over an angle of attack range from -10 to 10 deg at zero degrees sideslip and over a sideslip range from -10 to 10 deg at 0, +6, and -6 deg angle of attack. Mach number ranged from 0.6 to 4.96. The performance and stability characteristics of the complete ascent configuration and build-up, and the effects of variations in tank diameter, orbiter incidence, fairings and positioning of the solid rocket motors and tank fins were determined.

Sims, J. F.↗
NASA NTRS1985

Theoretical Thermodynamics of Mixtures at High Pressures

The development of an understanding of the chemistry of mixtures of metallic hydrogen and abundant, higher-z material such as oxygen, carbon, etc., is important for understanding of fundamental processes of energy release, differentiation, and development of atmospheric abundances in the Jovian planets. It provides a significant theoretical base for the interpretation of atmospheric elemental abundances to be provided by atmospheric entry probes in coming years. Significant differences are found when non-perturbative approaches such as Thomas-Fermi-Dirac (TFD) theory are used. Mapping of the phase diagrams of such binary mixtures in the pressure range from approx. 10 Mbar to approx. 1000 Mbar, using results from three-dimensional TFD calculations is undertaken. Derivation of a general and flexible thermodynamic model for such binary mixtures in the relevant pressure range was facilitated by the following breakthrough: there exists an accurate nd fairly simple thermodynamic representation of a liquid two-component plasma (TCP) in which the Helmholtz free energy is represented as a suitable linear combination of terms dependent only on density and terms which depend only on the ion coupling parameter. It is found that the crystal energies of mixtures of H-He, H-C, and H-O can be satisfactorily reproduced by the same type of model, except that an effective, density-dependent ionic charge must be used in place of the actual total ionic charge.

Hubbard, W. B.↗
NASA NTRS1986

Benchmark full configuration-interaction calculations on H2O, F- and F

Full configuration-interaction calculations are reported, and compared to other methods, for H2O at its equilibrium geometry and at two geometries with the H-O bonds stretched. Since the percentage of the self-consistent field (SCF) reference in the full configuration-interaction (FCI) wave function decreases greatly with the bond elongation, the accuracy of techniques based on a single reference do not compare well with the FCI results. However, the results from a complete active space SCF/multireference configuration-interaction (CASSCF/MRCI) treatment are in good agreement with the FCI. Correlation effects in F compared to Ne are far more similar than for F- compared to Ne, despite F- and Ne being isoelectronic. Since the importance of higher than double excitations is more important for F- than F, a very high percentage of the correlation must be obtained to accurately compute the electron affinity. In a CASSCF/MRCI treatment the higher than quadruple excitations contribute 0.02 eV to the electron affinity (EA), even for modest basis sets.

Bauschlicher, C. W., Jr.↗
NASA NTRS1986

Benchmark full configuration-interaction calculations on H2O, F, and

Full configuration-interaction calculations are reported, and compared to other methods, for H2O at its equilibrium geometry and at two geometries with the H-O bonds stretched. Since the percentage of the self-consistent field (SCF) reference in the full configuration-interaction (FCI) wave function decreases greatly with the bond elongation, the accuracy of techniques based on a single reference do not compare well with the FCI results. However, the results from a complete active space SCF/multireference configuration-interaction (CASSCF/MRCI) treatment are in good agreement with the FCI. Correlation effects in F compared to Ne are far more similar than for Fcompared to Ne, despite F- and Ne being isoelectronic. Since the importance of higher than double excitations is more important for F- than F, a very high percentage of the correlation must be obtained to accurately compute the electron affinity. In a CASSCF/MRCI treatment the higher than quadruple excitations contribute 0.02 eV to the electron affinity (EA), even for modest basis sets.

Bauschlicher, C. W., Jr.↗
NASA NTRS1993

Collision cross sections and diffusion parameters for H and D in atomic oxygen

Modeling the behavior of H and D in planetary exospheres requires detailed knowledge of the differential scattering cross sections for all of the important neutral-neutral and ion-neutral collision processes affecting these species over their entire ranges of interaction energies. In the upper atmospheres of Earth, Venus, and other planets as well, the interactions of H and D with atomic oxygen determine the rates of diffusion of escaping hydrogen isotopes through the thermosphere, the velocity distributions of exospheric atoms that encounter the upper thermosphere, the lifetimes of exospheric orbiters with periapsides near the exobase, and the transfer of momentum in collisions with hot O. The nature of H-O and D-O collisions and the derivation of a data base consisting of phase shifts and the differential, total, and momentum transfer cross sections for these interactions in the energy range 0.001 - 10 eV are discussed. Coefficients of mutual diffusion and thermal diffusion factors are calculated for temperatures of planetary interest.

Hodges, R. R., Jr.↗
NASA NTRS1994

Monte Carlo simulation of the terrestrial hydrogen exosphere

Methods for Monte Carlo simulation of planetary exospheres have evolved from early work on the lunar atmosphere, where the regolith surface provides a well defined exobase. A major limitation of the successor simulations of the exospheres of Earth and Venus is the use of an exobase surface as an artifice to separate the collisional processes of the thermosphere from a collisionles exosphere. In this paper a new generalized approach to exosphere simulation is described, wherein the exobase is replaced by a barometric depletion of the major constitents of the thermosphere. Exospheric atoms in the thermosphere-exosphere transition region, and in the outer exosphere as well, travel in ballistic trajectories that are interrupted by collisons with the background gas, and by charge exchange interactions with ionospheric particles. The modified simulator has been applied to the terrestrial hydrogen exosphere problem, using velocity dependent differential cross sections to provide statistically correct collisional scattering in H-O and H-H(+) interactions. Global models are presented for both solstice and equinox over the effective solar cycle range of the F(sub 10.7) index (80 to 230). Simulation results show significant differences with previous terrestrial exosphere models, as well as with the H distributions of the MSIS-86 thermosphere model.

Hodges, R. Richard, Jr.↗