Gap effect on the initiation of detonation of gas mixtures in cylindrical combustion chambers

A new mechanism is proposed for the occurrence of a number of phenomena in combustible gas mixtures described in the literature. This mechanism takes into account the possibility of reaction-zone propagation by pathways that were not envisaged in designing experimental setups. The process discovered more than 25 yr. ago and identified previously as autoignition of a shock-heated gas is considered in detail. This process has recently been used as experimental evidence for the existence of spontaneous (gradient and induction) flames. It is shown that this process actually involves mixture ignition by hot reaction products which issue into the chamber from the side of the detonation wave rather than combustible-mixture autoignition.