Numerical study of oblique detonation initiations with chain-branching kinetics

Abstract

Oblique detonations induced by semi-infinite wedge are simulated by solving Euler equations with chain branching kinetics. Numerical results show the initiation can be triggered by either the abrupt transition or smooth transition, dependent on incident Ma M in and wedge angle θ, and then their effects on the oblique detonation angle β and initiation length L ini are analyzed. When θ increases, L ini decreases monotonically but β has a minimum value, corresponding to θ = 29° in this study. When M in decreases, both L ini and β increases monotonically until M in decreases below certain critical value, M in = 9.2 in this study. Then low inflow Ma effects generate the maximum L ini , with the complex of ODW (oblique detonation wave), SODW (secondary oblique detonation wave) and SIDW (selfignition deflagration wave). The transient process is observed, demonstrating the structure can self-adjust to find a proper position. The wave structure suggests two wave/heat release process determining the detonation initiation. In the cases with high M in featured by SIDW, the oblique-shock induced self-ignition dominates, and L ini increases when M in decreases. In the cases with low M in featured by SODW, the interaction of ODW and SODW dominates, and L ini decreases when M in decreases.