Instability of wave complex resulting from oblique detonation decoupling

Oblique detonation wave (ODW) has been investigated widely for application in ramjet-type engines, but there are less works concerning its instability in a confined space. Recently, a wave complex induced by ODW decoupling has been observed, and this study investigates the instability of this wave complex featuring a recirculation zone. Numerical results show that the wave complex with recirculation zone oscillates, but the oscillations are found to be periodic rather than random, never reported before. The dependence of the period and frequency on the corner location and angle are analyzed in detail, with very irregular motion tracks of recirculation zone cores. Further quantitative analysis by Fast Fourier transformation reveals two origins of instability: one is the basic oscillation of the recirculation zone associated with the movement of surrounding wave complex; the other is self-excitation inside the recirculation zone, which makes its motion tracks more complicated than the external wave configuration.