Numerical prediction of envelope oscillation phenomena of shock-induced combustion

The envelope oscillation phenomenon, in which both high and low frequency oscillations are observed in the flowfields, of the shock-induced combustion is numerically investigated. The unsteady oscillation mode is classified by the induction time, and axisymmetric flow simulations are carried out. The classification reveals that the period of the envelope oscillation is essentially a low frequency oscillation. Histories on the stagnation streamline of the flow simulations show the low frequency oscillation, but several peaks are observed in one period of the low frequency oscillation. Moreover, the reaction front is always away from the bow shock wave, and the detonable reaction front is not established. The undeveloped detonable reaction front does not erase the corrugated pattern of the reaction boundary. Therefore, both high and low frequency oscillations are observed in the experimental and computational flowfields.