Decaying modes of propagation of detonation and flame front in acetylene–air mixture

Abstract

Decaying modes of a flame front propagation in narrow channel for acetylene–air mixtures were investigated experimentally using optical methods of diagnostics. Experiments were carried out using an open detonation channel of square cross section with transverse dimension of 3 mm and length of 1000 mm. It was connected to the detonation tube of 20 mm diameter and length of 3000 mm. A galloping decaying propagation of the combustion inside the narrow channel after the entry of a steady Chapman–Jouguet detonation into the channel was registered. It was shown that the propagation of detonation-like galloping combustion is possible in channels of subcritical size. Evolution of the flame front velocity was obtained. The time intervals of gallops and distance intervals were measured. After the decay of the detonation wave, the average velocity of the flame front decreases first to 1000 m/s, and then to 200 m/s.