STOCHASTIC ASPECT OF THE TRANSITION FROM COMBUSTION TO DETONATION

The transition from combustion to detonation in a stoichiometric propane-oxygen mixture is statistically investigated by using soot film traces. The probabilities for the detonation initiation and the triple shock formation are estimated from the distributions of the detonation initiation positions and the intervals between two successive triple shocks. The phenomena are explained by these probabilities. The detonation is initiated by an intense explosion behind the shock wave produced by the combustion wave. The shock wave propagates from the explosion position, enlarging the detonation region where many triple shocks are formed. The results also suggest that the triple shocks accompanied by an anomalously high pressure are formed in detonation not by collisions of pressure waves, but by spontaneous ignition which proceeds almost isochorically. © 1979 IOP Publishing Ltd.