Experimental Study on the Effect of Disturbed Tube on the Propagation Mechanism of Methane-Oxygen Detonation

Abstract

The detonation experiments of unstable mixture CH4 + 2O2 were carried out in smooth and disturbed tube under different initial pressures(P 0) to study the effects of inner tube disturbance(d) on the propagation velocity of detonation wave and the characteristics of cellular structure. The results show that these are mainly affected by the initial pressure and boundary conditions (confined wall). With the increase of P 0, the change trend of cell size remains unchanged whether there is disturbance or not. However, when P 0 rises to 15kPa, it can not offset the detonation failure caused by the d = 60mm tube. While, the turbulence effect caused by d = 20mm tube maintains the wave propagation through the flow fluctuation of leading shock wave and the interaction of boundary layer. When P 0 increases to 14kPa, the shear wave intensity of the detonation wave increases. The high initiation energy leads to the instability of the detonation wave front. A relatively fine secondary cellular structure is observed near the main cellular structure. So after inserting the inner tube disturbance, the decrease of cell size is due to the generation of secondary cellular structure, and the size of main cellular structure actually becomes larger.