Numerical study of reflector configuration design on shock wave focusing detonation initiation process

Numerical simulation research was carried out to study the effect of the parabolic cavity shape on detonation initiation process for shock wave focusing engine with kerosene as fuel. The results showed that the peak pressure in the cavity was decreased significantly as the depth of the cavity was enhanced. An umbrella-shaped aerodynamic structure which is composed by the expansion of the fan and two vortices was generated under the K–H instability effect when the supersonic jet entered into the cavity. When the inlet jet temperature was at ambient temperature (300 K) or set as 500 K, nearly no ignition was generated for all the three cavity configurations. As the jet temperature was increased to 600 K, the flame can be formed and stay in the cavity for all of these three cavities. However, the coupling between the flame propagation and the reflected shock wave is not close that detonation was not generated as well. As the inlet jet temperature was further increased to 700 K, the hot spot at the bottom of the cavity could be coupled with the reflected shock wave and detonation wave was successfully formed for all of these three cavity configurations.