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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 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Kinetic limitations on the diffusional control theory of the ablation rate of carbon.

It is shown that the theoretical maximum oxidation rate is limited in many cases even at temperatures much higher than 1650 deg K, not by oxygen transport, but by the kinetics of the carbon-oxygen reaction itself. Mass-loss rates have been calculated at air pressures of 0.01 atm, 1 atm, and 100 atm. It is found that at high temperatures the rate of the oxidation reaction is much slower than has generally been assumed on the basis of a simple linear extrapolation of Scala's 'fast' and 'slow' rate expressions. Accordingly it cannot be assumed that a transport limitation inevitably must be reached at high temperatures.

Maahs, H. G.↗
NASA NTRS1972

Continuing development of the short-pulsed ablative space propulsion system.

Major advancements have been made in solid propellant pulsed plasma propulsion technology. A LES-6 microthruster has operated for 8900 hours in orbit. Millipound thrustors have been developed and tested at performance levels of as low as 112 watts/mlb. Efficiencies of up to 50% and specific impulse values up to 5000 sec have been measured. An improved microthrustor has operated at 207 watts/mlb continuously for 1440 hours. Correlations of design and performance data exist to allow thrustors to be built to meet a particular level of performance.

Palumbo, D. J.↗
NASA NTRS1974

Glass fiber addition strengthens low-density ablative compositions

Approximately 15% of E-glass fibers was added to compositions under test and greatly improved char stability. Use of these fibers also reduced thermal strains which, in turn, minimized char shrinkage and associated cracks, subsurface voids, and disbonds. Increased strength allows honeycomb core reinforcement to be replaced by equivalent amount of glass fibers.

Chandler, H. H.↗
NASA NTRS1974

Interaction of gases with ablative composites. I - Ar, CO2, and N2

The sorption of argon, carbon dioxide, and nitrogen on two heat shield composites (SLA-561 and SLA-561V) and on the SLA components was measured over the pressure range of 0.001 to 760 torr and in the temperature range of 30 to 50 C. The sorption of the gases by both the composites and the components varied directly with pressure. The sorption of CO2 by the phenolic spheres and the silicone elastomer and of Ar by the silicone elastomer varied inversely with temperature. The mechanism involved in the gas sorption was primarily absorption.

King, C. A.↗
NASA NTRS1975

Chemical equilibrium of ablation materials including condensed species

Equilibrium is determined by finding chemical composition with minimum free energy. Method of steepest descent is applied to quadratic representation of free-energy surface. Solution is initiated by selecting arbitrary set of mole fractions, from which point on free-energy surface is computed.

Stroud, C. W.↗