An experimental study of detonation propagation and re-initiation for acetylene–air mixtures in a narrow channel

Abstract

Detonation propagation, re-initiation, and flame propagation in acetylene–air mixtures were investigated in a channel with a transverse dimension that is comparable with the width of the detonation cell. Experiments were carried out in a channel with a square cross-section of 5 mm $$\times $$ 5 mm. The detonation wave passed from the driver section into the transparent test section. The trajectories of the propagation of glowing combustion products (high-speed image sequences) were recorded, and high-speed schlieren image sequences of the reaction zone and shock waves were obtained. The flame front velocity was measured. The intensity of the shock waves was measured with piezoelectric pressure transducers. Depending on the equivalence ratio ER, four modes of combustion propagation were detected: (1) steady detonation; (2) decay and re-initiation of detonation; (3) detonation decay and flame acceleration; and (4) detonation decay and the absence of flame acceleration. Quantitative evaluation of the boundary layer thickness was carried out. The intensity of the shock wave and the flame front velocity were analysed for different modes. It was shown that the re-initiation of detonation in a mixture of acetylene and air with $$\text {ER} = 1.6$$ is characterized by a spatial interval of $$1000\pm 50$$ mm and a time interval of $$1300\pm 100~\upmu \hbox {s}$$ .