Hydrogen-enhanced spray flame propagation.

摘要

Recent interest in high speed aero-propulsion has stimulated consideration of a class of "endothermic fuels" which will serve as an airframe coolant while improving combustion performance. These fuels will thermally decompose and liberate hydrogen as they gain heat from the airframe and it is expected that the hydrogen will enhance combustion of the product hydrocarbon fuel.; In a first effort to investigate hydrogen-enhanced spray combustion, turbulent flame propagation rates were measured in fuel sprays modified by the addition of less than 3.6% hydrogen (by volume) to the combustion air. Experiments were conducted for the hydrocarbon fuels methylcyclohexane, toluene, decalin, and kerosene. For each fuel, flame speed data were obtained for several mixture strengths while varying the spray Sauter mean diameter from 30 to 90 microns.; Results show a surprising increase in flame speed with added hydrogen. The exact nature of the hydrogen-enhanced burning is seen to depend on the liquid fuel volatility. Under some conditions, hydrogen addition was observed to increase the hydrocarbon burning rate by more than a factor of two.