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May 24, 2011
05/11
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Alexander, M. J.; Holton, James R
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A two-dimensional cloud-resolving model is used to examine the possible role of gravity waves generated by a simulated tropical squall line in forcing the quasi-biennial oscillation (QBO) of the zonal winds in the equatorial stratosphere. A simulation with constant background stratospheric winds is compared to simulations with background winds characteristic of the westerly and easterly QBO phases, respectively. In all three cases a broad spectrum of both eastward and westward propagating...
Topics: CROSS FLOW, STOVL AIRCRAFT, LIFT, IMPINGEMENT, HOVERING, PRESSURE RATIO, PRESSURE DEPENDENCE, AIR...
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231
Jul 23, 2010
07/10
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Holdeman, J. D.; Reynolds, R.; White, C
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An analytical program was conducted to assemble and assess a three-dimensional turbulent viscous flow computer code capable of analyzing the flow field in the transition liners of small gas turbine engines. This code is of the TEACH type with hybrid numerics, and uses the power law and SIMPLER algorithms, an orthogonal curvilinear coordinate system, and an algebraic Reynolds stress turbulence model. The assessments performed in this study, consistent with results in the literature, showed that...
Topics: COMBUSTION, OXIDATION, OXIDES, FRICTION, IGNITION, METALS, OXYGEN, PRESSURE DEPENDENCE, TEMPERATURE...
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May 29, 2011
05/11
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Freeman, Jon C
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This short paper is in response to one that appeared in this journal a few years ago [2]. The article was a comment on a previous paper [1], which presented the transformation equations between the standard two-port parameters. The equations were stated to be valid for complex terminations; which are useful when S-parameters are treated. The authors in [2] made some incorrect conclusions concerning the concept of ''generalized scattering parameters'', and this paper seeks to clarify the...
Topics: VAPORS, SENSITIVITY, SUPERSATURATION, THERMAL DIFFUSION, CLOUD CHAMBERS, CONTINUITY EQUATION,...
Fan designs are often constrained by envelope, rotational speed, weight, and power. Aerodynamic performance and motor electrical performance are heavily influenced by rotational speed. The fan used in this work is at a practical limit for rotational speed due to motor performance characteristics, and there is no more space available in the packaging for a larger fan. The pressure rise requirements keep growing. The way to ordinarily accommodate a higher DP is to spin faster or grow the fan...
Topics: NASA Technical Reports Server (NTRS), CENTRIFUGAL FORCE, FAN BLADES, MECHANICAL ENGINEERING,...
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251
Jun 1, 2011
06/11
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Wallner, Lewis E.; Saari, Martin J
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As part of an investigation of the performance and operational characteristics of the TG-100A gas turbine-propeller engine, conducted in the Cleveland altitude wind tunnel, the performance characteristics of the compressor and the turbine were obtained. The data presented were obtained at a compressor-inlet ram-pressure ratio of 1.00 for altitudes from 5000 to 35,000 feet, engine speeds from 8000 to 13,000 rpm, and turbine-inlet temperatures from 1400 to 2100R. The highest compressor pressure...
Topics: EJECTORS, COMPRESSIBLE FLOW, PRESSURE DEPENDENCE, TEMPERATURE DISTRIBUTION, AIRCRAFT ENGINES,...
When a jet STOVL aircraft is hovering, or in a crossflow, while close to the ground wall jets flowing radially outward from the impingement points of the jets are generated. An upflow, or fountain, is generated where the wall jets from adjacent jets meet on the ground surface. The induced lift and suckdown generated by the impingement of the fountain on the lower surface of the configuration has been the subject of previous studies. This study analyzes the limited available pressure and force...
Topics: NASA Technical Reports Server (NTRS), CROSS FLOW, STOVL AIRCRAFT, LIFT, IMPINGEMENT, HOVERING,...
The recovery of hydrogen from such metal hydrides as LiH, MgH2, TiH2, CaH2 and FeTiH compounds is studied, with the aim of evaluating the viability of the technique for the storage of hydrogen fuel. The pressure-temperature dependence of the reactions, enthalpies of formation, the kinetics of the hydrogen absorption and desorption, and the mechanical and chemical stability of the metal hydrides are taken into account in the evaluation. Economic aspects are considered. Development of portable...
Topics: NASA Technical Reports Server (NTRS), ECONOMIC ANALYSIS, HYDROGEN FUELS, METAL HYDRIDES, STORAGE...
A method has been developed for machining MgO crystal blocks into forms for containing metallic and silicate liquids at temperatures up to 2,400 C, and pressures up to at least 320 kilobars. Possible custom shapes include tubes, rods, insulators, capsules, and guides. Key differences in this innovative method include drilling along the crystallographic zone axes, use of a vibration minimizing material to secure the workpiece, and constant flushing of material swarf with a cooling...
Topics: NASA Technical Reports Server (NTRS), FABRICATION, MACHINING, MAGNESIUM OXIDES, SINGLE CRYSTALS,...
A basic, experimental study on the hydrochlorination of silicon tetrachloride and metallurgical grade silicon with hydrogen gas to form trichlorosilane was carried out to greatly expand the range of reaction conditions. The equilibrium constant, K sub p, for the hydrochlorination reaction was measured as a function of temperature, pressure and concentration. The variation of the equilibrium constant as a function of temperature provided the measurement on the heat of reaction, delta H, by the...
Topics: NASA Technical Reports Server (NTRS), CHEMICAL EQUILIBRIUM, HYDROCHLORIDES, SILANES, SILICON...
It is shown that the most general second order tensor B sub ij which is zero for i not = j is proportional to the Kronecker delta (Delta sub ij). By a slight modification of that argument, the known result was obtained that the most general second order isotropic tensor is also proportional to Delta sub ij. These results are useful for instance in obtaining the stress tensor for a viscous fluid.
Topics: NASA Technical Reports Server (NTRS), CARTESIAN COORDINATES, PRESSURE DEPENDENCE, STRESS TENSORS,...
A composite nut is shown which permits a fastener to be inserted or removed from either side with an indicator of fastener engagement. The nut has a plurality of segments, preferably at least three segments, which are internally threaded, spring loaded apart by an internal spring, and has detents on opposite sides which force the nut segments into operative engagements with a threaded member when pushed in and release the segments for quick insertion or removal of the nut when moved out. When...
Topics: NASA Technical Reports Server (NTRS), LOCKING, NUTS (FASTENERS), ORBITAL ASSEMBLY, SPACE TOOLS,...
Tests in which metals were rubbed against themselves in oxygen have revealed that increasing oxygen pressure does not always increase the potential for ignition. It is believed that there exists a specific pressure above which convective heat loss due to higher oxygen density will overcome the potential increase in the oxidation rate afforded by the increase in oxygen pressure. Test results have shown that, once a specific oxygen pressure is exceeded, greater rates of frictional energy were...
Topics: NASA Technical Reports Server (NTRS), COMBUSTION, FRICTION, IGNITION, METALS, OXYGEN, PRESSURE...
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303
Jun 2, 2011
06/11
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Brooker, John E.; Ruff, Gary A
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The performance of five thermal mass flow meters, MKS Instruments 179A and 258C, Unit Instruments UFM-8100, Sierra Instruments 830L, and Hastings Instruments HFM-200, were tested on the KC-135 Reduced Gravity Aircraft in orthogonal, coparallel, and counterparallel orientations relative to gravity. Data was taken throughout the parabolic trajectory where the g-level varied from 0.01 to 1.8 times normal gravity. Each meter was calibrated in normal gravity in the orthogonal position prior to...
Topics: BALLOONS, STRESS-STRAIN RELATIONSHIPS, HISTOGRAMS, PRESSURE DEPENDENCE, CCD CAMERAS, OPTICAL...
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219
Jun 2, 2011
06/11
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Hooey, Becky; Foyle, David C.; Andre, Anthon
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The Taxiway Navigation and Situation Awareness (T-NASA) system is a suite of cockpit displays (com- posed oi a head-up display (HUD), and an electronic moving map (EMM) as shown in figure 1) designed in support of the Aero-Space Technology Enterprise research objective to maintain safety while tripling throughput in all weather conditions. The T-NASA taxi HUD uses scene-linked symbology, superimposed on the forward scene, to present taxi route information, situational awareness information, and...
Topics: EARTH ATMOSPHERE, PRESSURE DEPENDENCE, RADIATION ABSORPTION, SPECTRAL BANDS, INFRARED SPECTROSCOPY,...
A thermomechanical model for upper mantle convection was constructed such that the thickness and the structure of the lithosphere are determined self consistently by the heat transported by convection. In this study of the interaction between the lithosphere and upper mantle, strongly temperature and pressure dependent rheologies for both Newtonian and non-Newtonian creep mechanisms are employed. For a strictly temperature dependent rheology an insignificant amount of heat, less than 12.5 mW/sq...
Topics: NASA Technical Reports Server (NTRS), CONVECTIVE HEAT TRANSFER, MODELS, RHEOLOGY, GEOPHYSICS, HEAT...
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The following reports from the 2003 Air Transport Research Society (ATRS) World Conference were included for processing into the NA&SD database:The Yield of Emigration - Ethnic Air Transport as an Overlooked Customer Segment; Simulated Consumer Decisions: An Appication of Synthetically Generated Consumer Profiles; The Analyzing of Airport Accessibility in Incheon International Airport; Future Requirments and Concepts for Cabins of Blended Wing Body Configurations - A Scenario Based...
Topics: AEROSOLS, PLANETARY BOUNDARY LAYER, OPTICAL FIBERS, PRESSURE DEPENDENCE, REMOTE SENSING, WATER...
The mechanism of insulator-insulator triboelectric (contact) charging is being studied by the Electrostatics and Surface Physics Laboratory at KSC. The hypothesis that surface ion exchange is the primary mechanism is being tested experimentally. A two-phase model based on a small partial pressure of singly charged ions in an ambient ideal gas in equilibrium with a submonolayer adsorbed film will provide predictions about charging as a function Of ion mass, pressure, temperature, and surface...
Topics: NASA Technical Reports Server (NTRS), INSULATORS, PRESSURE DEPENDENCE, ELECTRIC CONTACTS,...
Most engineering materials, including some metals, most notably aluminum, burn in homogeneous combustion. 'Homogeneous' refers to both the fuel and the oxidizer being in the same phase, which is usually gaseous. The fuel and oxidizer are well mixed in the combustion reaction zone, and heat is released according to some relation like q(sub c) = delta H(sub c)c[((rho/rho(sub 0))]exp a)(exp -E(sub c)/RT), Eq. (1) where the pressure exponent a is usually close to unity. As long as there is enough...
Topics: NASA Technical Reports Server (NTRS), HETEROGENEITY, METAL COMBUSTION, FLAMMABILITY, BURNING RATE,...
No abstract available
Topics: NASA Technical Reports Server (NTRS), BURNING RATE, TITANIUM, COMBUSTION, FLAMMABILITY, DIAMETERS,...
Direct measurements of reaction rate constants and branching fractions for elementary reactions necessary in the modeling of the troposphere or stratosphere are provided. Details of reaction mechanisms are elucidated by studying pressure and temperature dependences of reactions, as well as by use of isotopic labels. Measurement techniques are improved for radical species in the laboratory. Progress and results in each area are given.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC CHEMISTRY, REACTION KINETICS, RECOMBINATION...
No abstract available
Topics: NASA Technical Reports Server (NTRS), AEROSPACE ENVIRONMENTS, LOW PRESSURE, LITHIUM BATTERIES,...
Membrane filtration such as Reverse Osmosis (RO) removes ions, proteins, and organic chemicals which are generally very difficult to remove using conventional treatment. Moreover, membrane is an absolute filtration method, so its treatment efficiency and performance are stable and predictable. We are currently working on the development of rotating RO membrane system. Dynamic rotating membrane filtration, which can produce a high shear rate, may be helpful to obtain high rejection of organic...
Topics: NASA Technical Reports Server (NTRS), REVERSE OSMOSIS, WASTE WATER, INORGANIC COMPOUNDS, ORGANIC...
Reaction kinetic measurements on the hydrochlorination of SiCl4 and metallurgical grade (m.g.) silicon metal were made at a wide range of experimental variables. The effect of pressure on the reaction rate was studied at 25 psig, 100 psig, 150 psig and 200 psig, respectively. Results of these experiments show a large pressure effect on the hydrochlorination reaction. As expected, higher pressures produce a higher equilibrium SiHC13 conversion, since the hydrochlorination reaction results in a...
Topics: NASA Technical Reports Server (NTRS), CHLORINATION, CHLORINE COMPOUNDS, HYDROGENATION, REACTION...
The flammability in oxygen-enriched atmospheres of commercially pure (CP) titanium rods as a function of diameter and test gas pressure was determined. Test samples of varying diameters were ignited at the bottom and burned upward in 70% O2/balance N2 and in 99.5+% O2 at various pressures. The burning rate of each ignited sample was determined by observing the apparent regression rate of the melting interface (RRMI) of the burning samples. The burning rate or RRMI increased with decreasing test...
Topics: NASA Technical Reports Server (NTRS), BURNING RATE, COMBUSTION, DIAMETERS, FLAMMABILITY, GAS...
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May 24, 2011
05/11
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Dibb, J. E.; Talbot, R. W.; Klemm, K. I.; Gregory, G. L.; Singh, H. B.; Bradshaw, J. D.; Sandholm, S. T
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Aerosol samples collected over the western Pacific during the NASA/Global Tropospheric Experiment Pacific Exploratory Mission (PEM-West A) expedition (September - October 1991) revealed mean Pb-210 concentrations in the free troposphere in the 5-10 fCi m(exp -3) STP range. Most soluble ionic aerosol-associated species were near detection limits [much less than 40 parts per trillion by volume (pptv)] in these same samples. The altitude distribution of O3 near Asia closely resembled that of...
Topics: ELECTROMAGNETIC ABSORPTION, THERMODYNAMICS, SCALE EFFECT, ENERGY LEVELS, AIR FLOW, COMPRESSIBLE...
Shock metamorphic features are the prime indicators for recognizing impact phenomena on Earth and other planetary bodies. Although the pressure dependence of shock features is well known, information about the influence of the preshock temperature is almost lacking. Especially in the case of large-scale impacts like Sudbury, it is expected that deep-seated crustal rocks were subjected to shock at elevated temperatures. Therefore, we continued to perform shock experiments at elevated...
Topics: NASA Technical Reports Server (NTRS), METAMORPHISM (GEOLOGY), METEORITE COLLISIONS, QUARTZ, SHOCK...
Development of a procedure to join the components of the Cassegrainian concentrator photovoltaic cell stack assembly was studied. Diffusion welding was selected as the most promising process, and was concentrated on exclusively. All faying surfaces were coated with silver to promote welding. The first phase of the study consisted of developing the relationship between process parameters and joint strength using silver plated steel samples and an isostatic pressure system. In the second phase,...
Topics: NASA Technical Reports Server (NTRS), DIFFUSION WELDING, FEASIBILITY ANALYSIS, GALLIUM ARSENIDES,...
Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and Earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or laboratory measurements...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, MICROWAVE ATTENUATION, PLANETARY...
Temperatures of CaAl2Si2O8 (anorthite glass) shocked to pressures between 48 and 117 GPa were measured in the range from 2500 to 5600 K, using optical pyrometry techniques. The pressure dependence of the shock temperatures deviates significantly from predictions based on a single high pressure phase. At least three phase transitions, at pressures of about 55, 85, and 100 GPa and with transition energies of about 0.5 MJ/kg each (approximately 1.5 MJ/kg total) are required to explain the shock...
Topics: NASA Technical Reports Server (NTRS), ANORTHOSITE, PRESSURE DEPENDENCE, TEMPERATURE MEASUREMENT,...
The influence of pressure on the autoignition characteristics of homogeneous mixtures of hydrocarbon fuels in air is examined. Autoignition delay times are measured for propane, ethylene, methane, and acetylene in a continuous flow apparatus featuring a multi-point fuel injector. Results are presented for mixture temperatures from 670K to 1020K, pressures from 1 to 10 atmospheres, equivalence ratios from 0.2 to 0.7, and velocities from 5 to 30 m/s. Delay time is related to pressure,...
Topics: NASA Technical Reports Server (NTRS), FIRING (IGNITING), IGNITION, PRESSURE DEPENDENCE, SPONTANEOUS...
In a microgravity environment vapor bubbles generated at a boiling surface tend to remain near it for a long time. This affects the boiling heat transfer and in particular promotes an early transition to the highly inefficient film boiling regime. This paper describes the physical basis underlying attempts to remove the bubbles by means of pressure radiation forces.
Topics: NASA Technical Reports Server (NTRS), BUBBLES, MICROGRAVITY, HEAT TRANSFER, ACOUSTIC PROPERTIES,...
Metal - metal and metal - insulator contact or triboelectric charging are well known phenomena with good theoretical understanding of the charge exchange mechanism. However, insulator - insulator charging is not as well understood. Theoretical and experimental research has been performed that shows that the surface charge on an insulator after triboelectric charging with another insulator is rapidly dissipated with lowered atmospheric pressure. This pressure discharge is consistent with surface...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC CHARGE, INSULATORS, PRESSURE DEPENDENCE, VAPOR...
All major classes of chondrites show signs of alteration on their parent bodies (asteroids). The prevalence of oxidation and hydration in alteration pathways implies that water was the major reactant. Sublimation and melting of water ice, generation of gases, formation of aqueous solutions, alteration of primary minerals and glasses and formation of secondary solids in interior parts of asteroids was likely to be driven by heat from the radioactive decay of short-lived radionuclides. Progress...
Topics: NASA Technical Reports Server (NTRS), THERMODYNAMICS, AQUEOUS SOLUTIONS, ASTEROIDS, PRESSURE...
Foams are extremely important in a variety of industrial applications. Foams are widely used in fire-fighting applications, and are especially effective in fighting flammable liquid fires. In fact the Fire Suppression System aboard the Space Shuttle utilizes cylinders of Halon foam, which, when fired, force a rapidly expanding foam into the convoluted spaces behind instrument panels. Foams are critical in the process of enhanced oil recovery, due to their surface-active and highly viscous...
Topics: NASA Technical Reports Server (NTRS), FOAMS, MECHANICAL PROPERTIES, MICROGRAVITY, RHEOLOGY,...
The purpose of this paper is to examine the key parameters that affect the bubble point pressure for screen channel Liquid Acquisition Devices in cryogenic liquid oxygen at elevated pressures and temperatures. An in depth analysis of the effect of varying temperature, pressure, and pressurization gas on bubble point is presented. Testing of a 200 x 1400 and 325 x 2300 Dutch Twill screen sample was conducted in the Cryogenics Components Lab 7 facility at the NASA Glenn Research Center in...
Topics: NASA Technical Reports Server (NTRS), BUBBLES, CRYOGENICS, LIQUID OXYGEN, TEMPERATURE EFFECTS,...
During assembly of the International Space Station, the Internal Thermal Control Systems in adjacent modules are connected by jumper hoses referred to as integrated hose assemblies (IHAs). A test of an IHA has been performed at the Marshall Space Flight Center to determine whether the pressure in an IHA filled with heat transfer fluid would exceed the maximum design pressure when subjected to elevated temperatures (up to 60 C (140 F)) that may be experienced during storage or transportation....
Topics: NASA Technical Reports Server (NTRS), INTERNATIONAL SPACE STATION, THERMAL EXPANSION, WORKING...
In an on-going effort to increase the safety and efficiency of turbine engines, the National Aeronautics and Space Administration is exploring lightweight alternatives to the metal containment structures that currently encase commercial jet engines. Epoxy reinforced with braided carbon fibers is a candidate structural material which may be suitable for an engine case. This paper reports flat-coupon mechanical-property experiments performed to compliment previously reported subcomponent impact...
Topics: NASA Technical Reports Server (NTRS), BRAIDED COMPOSITES, EPOXY RESINS, NASA PROGRAMS, TENSILE...
We report measurements of the depression of the superfluid transition temperature by a heat current (1 less than or = Q less than or = 100 microW/sq cm) along the lambda-line (SVP less than or = P less than or = 21.6 bar). At P = 21.6 bar, measurements were also performed in a reduced gravity (0.2g). Experimental results show that the pressure dependence of the depression and the gravity effect on the measurements are small, in qualitative agreement with theoretical predictions. Keywords:...
Topics: NASA Technical Reports Server (NTRS), PRESSURE DEPENDENCE, TRANSITION TEMPERATURE, TEMPERATURE...
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251
May 23, 2011
05/11
by
Taktakishvili, A.; Lopez, R. E.; Goodrich, C. C
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In this study we examine observations made by AMPTE/CCE of energetic ion bursts during seven substorm periods when the satellite was located near the neutral sheet, and CCE observed the disruption cross-tail current in situ. We compare ion observations to analytic calculations of particle acceleration. We find that the acceleration region size, which we assume to be essentially the current disruption region, to be on the order of 1 R(sub E). Events exhibiting weak acceleration had either...
Topics: ETHYL ALCOHOL, PRESSURE GRADIENTS, PRESSURE DEPENDENCE, REGENERATIVE COOLING, TUBES, WALL...
Differently oriented single crystal quartz was shocked experimentally at pressures of 20 to 32 GPa and pre-shock temperatures up to 630 C. Based on this systematic investigation, we can demonstrate that the orientation of planar deformation features in quartz is not only dependent on shock pressure but also on pre-shock temperature and shock direction. Moreover, the orientation of Planar Deformation Features (PDF's) is strongly influenced by the set-up in recovery experiments. PDF's in quartz...
Topics: NASA Technical Reports Server (NTRS), PLANAR STRUCTURES, PRESSURE DEPENDENCE, QUARTZ, SHOCK LOADS,...
A research program is being undertaken to develop rate dependent deformation and failure models for the analysis of polymer matrix composite materials. In previous work in this program, strain-rate dependent inelastic constitutive equations used to analyze polymers have been implemented into a mechanics of materials based composite micromechanics method. In the current work, modifications to the micromechanics model have been implemented to improve the calculation of the effective inelastic...
Topics: NASA Technical Reports Server (NTRS), POLYMER MATRIX COMPOSITES, DEFORMATION, STRAIN RATE, FAILURE...
The reactions, BrO + ClO yields Br + ClOO (1a) yields Br + OClO (1b) yields BrCl + O2 (1c) and ClO + ClO yields Cl + CiOO (2a) yields Cl + OClO (2b) yields Cl2 + O2 (2c) yields (ClO)2 (2d) have assumed new importance in explaining the unusual springtime depletion of ozone observed in the Antarctic stratosphere. The mechanisms of these reactions involve the formation of metastable intermediates which subsequently decompose through several energetically allowed products providing the motivation...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC CHEMISTRY, BROMIDES, CHLORINE COMPOUNDS, OZONE...
Lorentz air-broadened half widths, pressure-induced shifts and their temperature dependences have been measured for over 430 transitions (allowed and forbidden) in the v4 band of (CH4)-12 over the temperature range 210 to 314 K. A multispectrum non linear least squares fitting technique was used to simultaneously fit a large number of high-resolution (0.006 to 0.01/cm) absorption spectra of pure methane and mixtures of methane diluted with dry air. Line mixing was detected for pairs of A-, E-,...
Topics: NASA Technical Reports Server (NTRS), ABSORPTION SPECTRA, METHANE, PRESSURE DEPENDENCE, FOURIER...
Direct numerical simulation was used to study the formation and growth of a hairpin vortex in a flat-plate boundary layer and its later development into a young turbulent spot. Fluid injection through a slit in the wall triggered the initial vortex. The legs of the vortex were stretched into a hairpin shape as it traveled downstream. Multiple hairpin vortex heads developed between the stretched legs. New vortices formed beneath the streamwise-elongated vortex legs. The continued development of...
Topics: NASA Technical Reports Server (NTRS), DIRECT NUMERICAL SIMULATION, HORSESHOE VORTICES, TURBULENCE,...
The behavior of chemical elements during metal/silicate segregation and their resulting distribution in Earth's mantle and core provide insight into core formation processes. Experimental determination of partition coefficients allows calculations of element distributions that can be compared to accepted values of element abundances in the silicate (mantle) and metallic (core) portions of the Earth. Tungsten (W) is a moderately siderophile element and thus preferentially partitions into metal...
Topics: NASA Technical Reports Server (NTRS), CHEMICAL COMPOSITION, EARTH MANTLE, PARAMETERIZATION,...
Many volatile metal hydroxides form by reaction of the corresponding metal oxide with water vapor. These reactions are important in a number of high temperature corrosion processes. Experimental methods for studying the thermodynamics of metal hydroxides include: gas leak Knudsen cell mass spectrometry, free jet sampling mass spectrometry, transpiration and hydrogen-oxygen flame studies. The available experimental information is reviewed and the most stable metal hydroxide species are...
Topics: NASA Technical Reports Server (NTRS), HIGH TEMPERATURE, OXIDES, WATER VAPOR, CHEMICAL REACTIONS,...
A review of the equations used to determine the 1-D vapor transport in the thermal diffusion cloud chamber (TDCC) is presented. These equations closely follow those of the classical Stefan tube problem in which there is transport of a volatile species through a noncondensible, carrier gas. In both cases, the very plausible assumption is made that the background gas is stagnant. Unfortunately, this assumption results in a convective flux which is inconsistent with the momentum and continuity...
Topics: NASA Technical Reports Server (NTRS), VAPORS, THERMAL DIFFUSION, CLOUD CHAMBERS, CONTINUITY...
Hydrogen reduction of the lunar regolith simulants JSC-1A and LHT-2M is investigated in this paper. Experiments conducted at NASA Johnson Space Center are described and are analyzed utilizing a previously validated model developed by the authors at NASA Glenn Research Center. The effects of regolith sintering and clumping, likely in actual production operations, on the oxygen production rate are studied. Interpretations of the obtained results on the basis of the validated model are provided...
Topics: NASA Technical Reports Server (NTRS), LUNAR ROCKS, PARTICLE DIFFUSION, HYDROGEN, REGOLITH, SPECIES...
The formation of volatile Si-O-H species from silica occurs in water-vapor containing environments such as combustion environments. In this paper the pressure and temperature dependence of known Si-O-H species are surveyed. Trends based on the number of water molecules incorporated in the Si-O-H species are identified. Larger molecules (more OH groups) tend to have a higher pressure dependence and lower temperature dependence. These trends are then used to identify possible unknown species...
Topics: NASA Technical Reports Server (NTRS), TEMPERATURE DEPENDENCE, FUEL COMBUSTION, PRESSURE DEPENDENCE,...
In support of the U.S. Department of Energy's Stirling Engine Highway Vehicle Systems program, the NASA Lewis Stirling engine performance code was evaluated by comparing code predictions without engine-specific calibration factors to GPU-3, P-40, and RE-1000 Stirling engine test data. The error in predicting power output was -11 percent for the P-40 and 12 percent for the Re-1000 at design conditions and 16 percent for the GPU-3 at near-design conditions (2000 rpm engine speed versus 3000 rpm...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, ENGINE CONTROL, HYSTERESIS,...
