High resolution numerical simulation of methane explosion in bend ducts

In this paper we developed a parallel code, adopting a fifth-order weighted essentially non-oscillatory (WENO) scheme with a third-order TVD Runge-Kutta time stepping method for the two-dimensional reactive Euler equations, to investigate the propagation process of methane explosion in bend ducts. In the simulations, an inverse Lax-Wendroff procedure is adopted to construct a high order boundary in order to treat the complex boundaries. The numerical results show that when the bend angle is 30° and 45°, it cannot inhibit the propagation of the detonation wave; while when the angle reaches 60° and 75°, the detonation wave finally attenuates to the shock wave. It indicates that the propagation of the detonation wave can be inhibited. Furthermore, the temperature and the pressure at the entrance of the bend are low. When the angle arrives at 90°, the detonation wave evolves into cellular detonation when it passes through the bend. When the angle is larger than 90°, the detonation wave dramatically attenuates at the diffracting point, and later some hot spots can be formed, which can ignite the combustible gas nearby. Thus the second explosion occurs and finally the detonation is formed. When the angle is larger than or equal to 90°, the temperature and the pressure at the entrance of the bend is too high that the rescue efforts in the methane explosion accidents will encounter great difficulties. Hence, the laneway with 60° and 75° bend can inhibit the propagation of the detonation wave, and the temperature and the pressure at the entrance of the bend is not too high as well. All the results above can provide an important basis for the design and optimization of the mine laneway.