Experimental investigation of methane-oxygen detonation propagation in tubes

In this study, the detonation behaviors of methane-oxygen with five equivalence ratios (phi = 0.5, 0.667, 1, 1.333, 2) were investigated experimentally. Two 32-mm inner diameter round tubes were used, i.e., a smooth tube and a porous tube, to study the effect of different walls on the detonation limits. Fiber optical sensors was employed to capture the signals of the detonation wave, from which the velocity can be determined. Smoked foils were inserted into the smooth to register the cellular structure. The results indicate that in the smooth tube, the detonation propagates at a steady velocity within the limit. The stable spinning detonation is observed in a range of the initial pressure. Below the limits, no steady velocity and cell structure can be observed. In the porous tube, the detonation limits are elevated significantly. Within the limits, the detonation propagates at a velocity more than 0.70V(CJ). Below the limits, the decoupled deflagration can hold a steady velocity at about 0.4V(CJ) similar to 0.5V(CJ). The failure condition for the mixture at phi = 0.5 is d/lambda approximate to 6. For other mixtures, the detonation fails at d/lambda approximate to 4. (C) 2017 Published by Elsevier Ltd.