Parametric study of hydrogen concentration on detonation initiation by shock focusing

Abstract

Previous studies indicated that shock focusing is an effective way leading to detonation initiation. Hydrogen concentration as an operating condition is crucial to detonation initiation when the combustible gas is a mixture of hydrogen-air. To discuss the effect of hydrogen concentration, simulations of initiation by shock focusing with different hydrogen concentrations are performed. This paper provides an analysis of initiation by fuel in different amounts (in rich, stoichiometric, and lean). The initiation behaviors of shock focusing with different hydrogen concentrations (range from 20 vol% to 60 vol%) are discussed. The results show that high hydrogen concentration on initiation is significantly effective in accelerating the attenuation of overdriven detonation, which is conducive to initiating a quick and stable detonation initiation. An examination also shows that detonation failure is more likely caused by lean fuel mixtures. As to rich and stoichiometric fuel, there is the same physical mechanism for detonation initiation.