EFFECT OF NONISENTROPIC PROCESSES ON TRANSITION FROM COMBUSTION TO DETONATION IN COMBUSTIBLE MIXTURES

The problem of spontaneous combustion of a compressible reacting gas i n a wall boundary layer behind a single shock wave in a tube with an a diabatic wall is examined. The possibility of leading spontaneous comb ustion of the gas in the boundary layer compared with spontaneous comb ustion in the flow core is shown in an approximation of a one-stage ch emical reaction. Explosion in the boundary layer occurs locally, and i n the vicinity of the exploding gas particle there is a finite gradien t of the spontaneous-combustion induction time. The calculated velocit y of the spontaneous-combustion (spontaneous-flame) wave is close to t he local sound velocity, which indicates the possibility of the genera tion of a strong blast wave. With consideration of the nonadiabatic ch aracter of the wall, the investigated effect is manifested as a result of multiple compression of the the reacting mixture by shock waves or simple compression waves, as well as for a wall made of a material wi th a low thermal conductivity.