Detailed mechanism of the unsteady combustion around hypersonic projectiles

Flow features of an unsteady shock-induced combustion around projectiles are numerically studied using a finite difference method. The large-disturbance regime of the unsteady combustion, characterized by a low-frequency and high-amplitude oscillation, is investigated by a series of simulations considering an oxygen-hydrogen combustion mechanism under the same condition as the experiment. The time-evolving flowfield is obtained in the simulation, and the mechanism of the unsteady phenomenon is investigated. The mechanism on the stagnation streamline agrees with our previously proposed model using a simplified chemical reaction model. Several detailed features characterizing the large-disturbance regime of unsteady combustion are revealed in the computations, and an improved mechanism is proposed. The grid refinement study is carried out to confirm that the flow features obtained are grid independent and are not fictitious.