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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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NASA NTRS1987

Catalytic, hollow, refractory spheres

Improved, heterogeneous, refractory catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitable formed of a shell (12) of refractory such as alumina having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be itself catalytic or a catalytically active material coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

Wang, Taylor G.↗

NASA NTRS1989

Catalytic, hollow, refractory spheres, conversions with them

Wang, Taylor G.↗

NASA NTRS1974

Slip conditions with wall catalysis and radiation for multicomponent, nonequilibrium gas flow

The slip conditions for a multicomponent mixture with diffusion, wall-catalyzed atom recombination and thermal radiation are derived, and simplified expressions for engineering applications are presented. The gas mixture may be in chemical nonequilibrium with finite-rate catalytic recombination occurring on the wall. These boundary conditions, which are used for rarefied flow regime flow field calculations, are shown to be necessary for accurate predictions of skin friction and heat transfer coefficients in the rarefied portion of the space shuttle trajectory.

Hendricks, W. L.↗

NASA NTRS1973

Wall boundary equations with slip and catalysis for multicomponent, nonequilibrium gas flows

Boundary equations obtained for a low Reynolds number, high enthalpy gas flow in regions of velocity slip and temperature jump are presented. The formulation treats, through a first-order distribution function used to include multicomponent diffusion, a multicomponent gas mixture that may be in nonequilibrium with finite-rate catalytic recombination occurring on the wall. In the boundary equations, which are obtained for use in flow-field calculations applicable to low-density flow regimes, a simplified gas/wall interaction is assumed wherein individual atoms or molecules either reflect specularly off the wall or stick and are fully accommodated. Fluxes in terms of evaluated integrals over the distribution function and integrals necessary for determining fluxes are given.

Scott, C. D.↗

NASA NTRS1986

Heat and mass transfer in a dissociated laminar boundary layer of air with consideration of the finite rate of chemical reaction

A numerical investigation of heat and mass transfer in a dissociated laminar boundary layer of air on an isothermal flat plate is carried out for different degrees of cooling of the wall. A finite-difference chemical model is used to study elementary reactions involving NO2 and N2O. The analysis is based on equations of continuity, momentum, energy, conservation and state for the two-dimensional viscous flow of a reacting multicomponent mixtures. Attention is given to the effects of both catalyticity and noncatalyticity of the wall.

Oyegbesan, A. O.↗

NASA NTRS1989

The use of atmospheric braking during Mars missions

The use of a high-lift, winged atmospheric entry-glide vehicle by an early Mars manned mission lasting 14-16 months allows the effective use of atmospheric braking to decelerate upon arrival at Mars. Following nearly-constant deceleration, the vehicle skips out of the atmosphere into a low planetary orbit. The maximum atmospheric heating rate thus generated is of the order of 100 W/sq cm at the stagnation point for a fully catalytic surface; the corresponding equilibrium wall temperature was 2150 K. The vehicle envisioned could be radiatively cooled to an entry speed of over 8 km/sec.

Tauber, M. E.↗

NASA NTRS1990

Cooling system and insulation concept for a Mach 5 turbo-ramjet aircraft

A cooling system and insulation concept for a Mach 5 cruise aircraft, using non-cryogenic fuel is presented. Catalytic endothermic reaction of petroleum fuel is used as the heat sink for engine cooling. A secondary closed-loop coolant circuit removes heat from the engine and transfers this heat to the catalytic reactor. Insulation on the engine flow path surfaces reduces the cooling requirements. A high temperature insulation system, which is capable of a surface temperature of 4,000 F, is used for the combustor and nozzle. A complete closed-loop cooling system design is shown in detail. Main features of this system include a fuel preheater, a catalytic fuel reactor, and engine wall cooling panels. A silicone-based liquid polymer, designed for extended use at 750 F, is used as the coolant. The preheater and reactor design are based on the results of recent experimental work. The cooling panels are designed using a thermal fluid analysis computer program, which was originally developed for the National Aero-Space Plane (NASP). Major components are analyzed structurally as well as thermally and weights are presented.

Jones, S. C.↗

NASA NTRS1993

Computation of nonequilibrium shock layers for the comet sample return vehicles

This paper contains computational results for the flow around the body of the 'Rosetta' spacecraft. The flow is computed for the predicted trajectory point of maximum heating, using a Navier-Stokes solver coupled to the chemical kinetics. The calculations are performed for catalytic and non-catalytic boundary conditions at the wall, and with a systematic grid sensitivity study. The calculations verify some of the assumptions made in an early study, and predict the location of peak convective heating.

Cambier, Jean-Luc↗

NASA NTRS2009

Improvements in Production of Single-Walled Carbon Nanotubes

A continuing program of research and development has been directed toward improvement of a prior batch process in which single-walled carbon nanotubes are formed by catalytic disproportionation of carbon monoxide in a fluidized-bed reactor. The overall effect of the improvements has been to make progress toward converting the process from a batch mode to a continuous mode and to scaling of production to larger quantities. Efforts have also been made to optimize associated purification and dispersion post processes to make them effective at large scales and to investigate means of incorporating the purified products into composite materials. The ultimate purpose of the program is to enable the production of high-quality single-walled carbon nanotubes in quantities large enough and at costs low enough to foster the further development of practical applications. The fluidized bed used in this process contains mixed-metal catalyst particles. The choice of the catalyst and the operating conditions is such that the yield of single-walled carbon nanotubes, relative to all forms of carbon (including carbon fibers, multi-walled carbon nanotubes, and graphite) produced in the disproportionation reaction is more than 90 weight percent. After the reaction, the nanotubes are dispersed in various solvents in preparation for end use, which typically involves blending into a plastic, ceramic, or other matrix to form a composite material. Notwithstanding the batch nature of the unmodified prior fluidized-bed process, the fluidized-bed reactor operates in a continuous mode during the process. The operation is almost entirely automated, utilizing mass flow controllers, a control computer running software specific to the process, and other equipment. Moreover, an important inherent advantage of fluidized- bed reactors in general is that solid particles can be added to and removed from fluidized beds during operation. For these reasons, the process and equipment were amenable to modification for conversion from batch to continuous production.

Balzano, Leandro↗

NASA NTRS1990

Thermal management for a Mach 5 cruise aircraft using endothermic fuel

The present thermal management system for a carrier-based Mach 5 cruise-capable aircraft whose propulsion system does not entail cryogenic fuels is predicated on the use of the catalytic endothermic reaction of a petroleum-derived hydrocarbon fuel as the heat sink for engine cooling. The insulation of engine flowpath surfaces reduces cooling requirements. The primary elements of this closed-cycle cooling system are a fuel preheater, a catalytic fuel reactor, and engine wall-cooling panels; a silicone-based liquid polymer is used as the coolant. Structural, weight, and thermal analysis results are presented for each of the primary components.

Petley, Dennis H.↗

NASA NTRS2006

Transparent and Electrically Conductive Carbon Nanotube-Polymer Nanocomposite Materials for Electrostatic Charge Dissipation

In recent years, nanocomposite materials have been extensively studied because of their superior electrical, magnetic, and optical properties and large number of possible applications that range from nano-electronics, specialty coatings, electromagnetic shielding, and drug delivery. The aim of the present work is to study the electrical and optical properties of carbon nanotube(CNT)-polymer nanocomposite materials for electrostatic charge dissipation. Single and multi-wall carbon nanotubes were grown by catalytic chemical vapor deposition (CCVD) on metal/metal oxide catalytic systems using acetylene or other hydrocarbon feedstocks. After the purification process, in which amorphous carbon and non-carbon impurities were removed, the nanotubes were functionalized with carboxylic acid groups in order to achieve a good dispersion in water and various other solvents. The carbon nanostructures were analyzed, both before and after functionalization by several analytical techniques, including microscopy, Raman spectroscopy, and X-Ray photoelectron spectroscopy. Solvent dispersed nanotubes were mixed (1 to 7 wt %) into acrylic polymers by sonication and allowed to dry into 25 micron thick films. The electrical and optical properties of the films were analyzed as a function of the nanotubes' concentration. A reduction in electrical resistivity, up to six orders of magnitude, was measured as the nanotubes' concentration in the polymeric films increased, while optical transparency remained 85 % or higher relative to acrylic films without nanotubes.

Dervishi, E.↗

NASA NTRS2007

Re-Entry Aeroheating Analysis of Tile-Repair Augers for the Shuttle Orbiter

Computational re-entry aerothermodynamic analysis of the Space Shuttle Orbiter s tile overlay repair (TOR) sub-assembly is presented. Entry aeroheating analyses are conducted to characterize the aerothermodynamic environment of the TOR and to provide necessary inputs for future TOR thermal and structural analyses. The TOR sub-assembly consists of a thin plate and several augers and spacers that serve as the TOR fasteners. For the computational analysis, the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) is used. A 5-species non-equilibrium chemistry model with a finite rate catalytic recombination model and a radiation equilibrium wall condition are used. It is assumed that wall properties are the same as reaction cured glass (RCG) properties with a surface emissivity of epsilon = 0.89. Surface heat transfer rates for the TOR and tile repair augers (TRA) are computed at a STS-107 trajectory point corresponding to Mach 18 free stream conditions. Computational results show that the average heating bump factor (BF), which is a ratio of local heat transfer rate to a design reference point located at the damage site, for the auger head alone is about 1.9. It is also shown that the average BF for the combined auger and washer heads is about 2.0.

Mazaheri, Ali R.↗

NASA NTRS1977

Process of forming catalytic surfaces for wet oxidation reactions

A wet oxidation process was developed for oxidizing waste materials, comprising dissolved ruthenium salt in a reactant feed stream containing the waste materials. The feed stream is introduced into a reactor, and the reactor contents are then raised to an elevated temperature to effect deposition of a catalytic surface of ruthenium black on the interior walls of the reactor. The feed stream is then maintained in the reactor for a period of time sufficient to effect at least partial oxidation of the waste materials.

Jagow, R. B.↗

NASA NTRS1984

Catalytic surface effect on ceramic coatings for an aeroassisted orbital transfer vehicle

Surface catalytic efficiencies of glassy coatings were determined from a reaction boundary layer computation and arc-jet data. The catalytic efficiencies of the various coatings examined are discussed in terms of their reaction-rate constants. These constants are a function of the wall temperature (1290 K to 2000 K). In addition, the advantage of a thermal protection system for a bent biconic, aeroassisted orbital transfer vehicle with a low surface catalytic efficiency is discussed.

Steward, D. A.↗

NASA NTRS2000

New genes and new biological roles for expansins

Expansins are extracellular proteins that loosen plant cell walls in novel ways. They are thought to function in cell enlargement, pollen tube invasion of the stigma (in grasses), wall disassembly during fruit ripening, abscission and other cell separation events. Expansins are encoded by two multigene families and each gene is often expressed in highly specific locations and cell types. Structural analysis indicates that one expansin region resembles the catalytic domain of family-45 endoglucanases but glucanase activity has not been detected. The genome projects have revealed numerous expansin-related sequences but their putative wall-loosening functions remain to be assessed.

NASA Program Fundamental Space Biology↗

NASA NTRS1999

Lightweight Exhaust Manifold and Exhaust Pipe Ducting for Internal Combustion Engines

An improved exhaust system for an internal combustion gasoline-and/or diesel-fueled engine includes an engine exhaust manifold which has been fabricated from carbon- carbon composite materials in operative association with an exhaust pipe ducting which has been fabricated from carbon-carbon composite materials. When compared to conventional steel. cast iron. or ceramic-lined iron paris. the use of carbon-carbon composite exhaust-gas manifolds and exhaust pipe ducting reduces the overall weight of the engine. which allows for improved acceleration and fuel efficiency: permits operation at higher temperatures without a loss of strength: reduces the "through-the wall" heat loss, which increases engine cycle and turbocharger efficiency and ensures faster "light-off" of catalytic converters: and, with an optional thermal reactor, reduces emission of major pollutants, i.e. hydrocarbons and carbon monoxide.

Northam, G. Burton↗

NASA NTRS2002

Carbon Nanotubes Growth on Graphite Fibers

Carbon nanotubes (CNT) were synthesized on graphite fibers by thermal Chemical Vapor Deposition (CVD). On the fiber surface, iron nanoparticles are coated and act as catalysts for CNT growth. The growth temperature ranges from 550 to 1000 C at an ambient pressure. Methane and hydrogen gases with methane contents of 10% to 100% are used for the CNT synthesis. At high growth temperatures (greater than 800 C), the rapid inter-diffusion of the transition metal iron on the graphite surface results in a rough fiber surface with no CNT grown on the surface. When the growth temperature is relatively low (650 - 800 C), CNT are fabricated on the graphite surface with catalytic particles on the nanotube top ends. Using micro Raman spectroscopy in the breath mode region, single-walled or multi-walled CNT can be determined, depending on methane concentrations.

Zhu, Shen↗

NASA NTRS1971

Solutions for Reacting and Nonreacting Viscous Shock Layers with Multicomponent Diffusion and Mass Injection

Numerical solutions are presented for the viscous shocklayer equations where the chemistry is treated as being either frozen, equilibrium, or nonequilibrium. Also the effects of the diffusion model, surface catalyticity, and mass injection on surface transport and flow parameters are considered. The equilibrium calculations for air species using multicomponent: diffusion provide solutions previously unavailable. The viscous shock-layer equations are solved by using an implicit finite-difference scheme. The flow is treated as a mixture of inert and thermally perfect species. Also the flow is assumed to be in vibrational equilibrium. All calculations are for a 45 deg hyperboloid. The flight conditions are those for various altitudes and velocities in the earth's atmosphere. Data are presented showing the effects of the chemical models; diffusion models; surface catalyticity; and mass injection of air, water, and ablation products on heat transfer; skin friction; shock stand-off distance; wall pressure distribution; and tangential velocity, temperature, and species profiles.

Moss, J. N.↗