环形通道内爆轰波的起爆机制

The design of annular combustion chamber and pre-detonation tube of rotary detonation engines is the key factor affecting the ignition performance of the engines. In order to obtain the detonation initiation mechanism in an annular combustion chamber, the multi-frame short-time shutter-opening method was used in experiment to study the propagation process and mode of the detonation wave of acetylene and oxygen with different argon dilutions entering an annular channel tangentially through a straight pipe. We focus on the mechanism of detonation wave failure and reinitiation. By analyzing the cellular mode, it is found that the propagation mode of the detonation wave in the annular channel can be divided into three states: subcritical, critical and supercritical. The detonation wave in the annular channel propagates clockwise and counterclockwise at the same time. Depending on the initial pressure and the width of the channel, there can be a mode of complete detonation, a mode of detonation-reignition, and a mode of no detonation at all, corresponding to subcritical, critical and supercritical states. The order in which the three states appear in the clockwise and counterclockwise directions are not consistent, and the counterclockwise propagation is more likely to be extinguished. The study also found that reinitiation is achieved in two ways. One is by decoupling the reflection of the detonation wave from the inner wall surface and the subsequent lateral detonation wave, and the other is by burning to detonation. By analyzing the critical tube diameter of the straight tube, it is found that the critical tube diameter approaches the unstable detonation in the classical diffraction problem as the width of the channel increases, regardless of whether the detonation wave of acetylene and oxygen is diluted by high concentration or low concentration of argon gas. The experimental results can provide technical support for the structural design of the combustion chamber and pre-detonation tube of rotary detonation engines.