Study on the flow characteristics in the non-detonation reaction zones of wedge-induced oblique detonation transitions

Abstract

Wedge-induced oblique detonation transitions are simulated numerically to investigate the non-detonation reaction zone structures that include induction and deflagration regions. Compressible reactive Euler equations are solved using a seventh-order Weighted Essentially Non-Oscillatory (WENO) scheme on an adaptive mesh. Quasi-one-dimensional primitive variables along the streamline of oblique detonation are used to study the flow characteristics inside the non-detonation reaction zones of different types of initiation structures. For a smooth transition, the fluid along the streamline of the entire non-detonation zone is in an expansion state. The gradual increase in the oblique shock angle during the pressure wave's upward movement is the primary reason for the reaction length reduction along the y-direction. For a weak abrupt-type transition, the fluid near the wedge surface is in a state of expansion. Along the y-direction, the gradual increase in the oblique shock angle and the compressibility of the fluid ahead of the main reaction zone are the two main reasons for the reduction in reaction length. For a strong-abrupt transition, the fluid near the wedge surface is still in a state of expansion. Along the y-direction, the sharp increase in the degree of compressibility ahead of the main reaction zone is the main reason for the reduction in reaction length. Comparing the reaction length of the theoretical analysis with the simulation results, it is found that the hypothesis of constant pressure combustion (CPC) along the inclined wedge surface is more appropriate than the hypothesis of constant volume combustion (CVC).