Effects of Variable Total Pressures on Instability and Extinction of Rotating Detonation Combustion

Instability, extinction and re-initiation of rotating detonation in a two-dimensional Rotating Detonation Engine (RDE) configuration are numerically investigated, and the emphasis is laid on the effects of variable total pressures on the above combustion dynamics. Two conditions, i.e. different constant pressures and time-varying pressures, are considered to investigate the combustion instability in RDE. It is seen that under constant pressure condition the rotating detonation is more prone to instability at low pressure, due to the instability from the deflagrative surface. The intrinsic frequency for the unstable cases with different pressures is close, and maybe related to the RDE configuration and/or fuel properties. For the time-varying pressures with various specified frequencies, the RDE shows the different levels of instability characterized by multiple frequencies. The dominant frequencies vary, depending on the competition between the forced external frequency and the intrinsic one induced by the RDE system. About the extinction of continuously rotating detonation, it can be found that when the total pressure is reduced to a relatively lower value the detonation is quenched and left with deflagrative combustion. Furthermore, when the total pressure is increased based on the extinguished flow fields, detonation fronts are re-initiated due to the local high pressure. The stochasticity in RDE re-initiation has been found, in terms of the location and number of initial detonation front, the propagation direction, their interaction and final stabilization.