Effect of nonisentropic processes on transition from combustion to detonation in combustible mixtures

The problem of spontaneous combustion of a compressible reacting gas in a wall boundary layer behind a single shock wave in a tube with an adiabatic wall is examined. The possibility of leading spontaneous combustion of the gas in the boundary layer compared with spontaneous combustion in the flow core is shown in an approximation of a one-stage chemical reaction. Explosion in the boundary layer occurs locally, and in the vicinity of the exploding gas particle there is a finite gradient of the spontaneous-combustion induction time. The calculated velocity of the spontaneous-combustion (spontaneous-flame) wave is close to the local sound velocity, which indicates the possibility of the generation of a strong blast wave. With consideration of the nonadiabatic character of the wall, the investigated effect is manifested as a result of multiple compression of the reacting mixture by shock waves or simple compression waves, as well as for a wall made of a material with a low thermal conductivity.