Experimental investigations of detonation initiation by hot jets in supersonic premixed flows

A new method to initiate and sustain the detonation in supersonic flow is investigated. The reaction activity of coming flow may influence the result of detonation initiation. When a hot jet initiates a detonation wave successfully, there may exist two types of detonations. If the detonation velocity is greater than the velocity of coming flow, there will be a normal detonation here. Because of the influence of boundary layer separation, the upstream detonation velocity is much greater than the Chapman-Jouguet (CJ) detonation velocity. On the other hand, if the detonation velocity is less than the velocity of coming flow, an oblique detonation wave (ODW) will form. The ODW needs a continuous hot jet to sustain itself. If the pressure of jet is lower than a certain value, the ODW will decouple. In contrast the normal detonation wave can sustain itself without the hot jet.