Descriptions of Hydrogen-Oxygen Chemical Kinetics for Chemical Propulsion
CALIFORNIA UNIV SAN DIEGO LA JOLLA DEPT OF THE AEROSPACE AND MECHANICAL ENGINEERING SCIENCES
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There are many propulsion applications for which hydrogen and oxygen are attractive as fuel and oxidizer. These include liquid-propellant rocket motors with high specific impulse, air-breathing ramjets with supersonic combustion and certain types of pulse-detonation engines. Detailed knowledge of the chemical kinetics of combustion of hydrogen and oxygen is needed for rational design of combustors for such applications. Since there are only twenty-some steps in hydrogen-oxygen combustion chemistry, it is possible to ascertain all of the relevant rate parameters for this system much more accurately than for other fuel-oxidizer combinations. Although the relevant rate parameters are now rather well known, there are still some notable uncertainties that deserve further investigation. These include the falloff behavior at high pressures and chaperon efficiencies of various third bodies. More than twenty different mechanisms are currently available in the literature, some quite new. Predictions of these different mechanisms are in good agreement for most processes. There are, however, notable differences in predictions of autoignition induction times near crossover, where the rate of H O2 - OH O equals the rate of H O2 M - HO2 M. Even certain very recent mechanisms are in poor agreement with experiment in this respect. A mechanism is given here that agrees well with experiment. A very simple mechanism consisting of only six irreversible elementary steps actually provides excellent agreement for autoignition delays over a very wide range of conditions. Simplifications of this type can be useful in computational fluid dynamics of reacting flows and in various practical propulsion calculations.
- Inorganic Chemistry
- Liquid Propellant Rocket Engines