Influence of obstacles on shock wave propagation of gas explosion

In order to study the influence of non-flame area blocking plate on gas explosion pressure in different positions in the pipeline, an 18 m long arch pipe test platform was established, besides, based on FLUENT software, the gas explosion pressure and flame change at 6.75 m and 11.25 m positions without blocking plate and with 0.2 blocking rate in non-flame area were simulated and analyzed.This paper studies the change of the gas explosion pressure peak value at different measuring points by the blocking plate in the non-flame area, qualitatively analyzes the influence law of the three blocking rates on the pressure peak value at 6.75 m, and analyzes the action mechanism of the blocking plate on the gas explosion in the non-flame area.The results show that under the condition of no blocking plate, the peak pressure of each measuring point in the pipeline increases first, then decreases and then increases with the increase of distance, and the peak pressure at 11.25 m is greater than that at 6.75 m.When the blocking plate is added in the non-flame area, the maximum pressure in the pipeline appears ahead of time to 6.5 m due to the joint action of shock wave and reflected wave.When the blocking plate with blocking ratio of 0.2 is increased, the pressure peak at 6.75 m in the pipeline is increased.When the blocking ratio is 0.6,the flame propagation of gas explosion is restrained by reflected waves.Compared with 0.2 and 0.4 blocking rates, the maximum pressure in the pipeline decreases obviously.The peak pressure of gas explosion at 6.75 m increases first and then decreases with the increase of blocking ratio.When ignition occurs at 0.25 m, two reaction groups appear in the pipeline, the gas mass after 0.25 m has a great influence on the explosion pressure, and the reaction speed at 0-0.25 m is slow.Due to the limitation of pipe shape and ignition position, the flame propagation speed at the lower end of arch pipe is faster, and the blocking plate with 0.2 blocking rate is added.The simulation results show that the flame contraction time point is 15 ms ahead of time, and the pressure drop trend at No.4 and No.7 measuring points becomes slow.In the simulation results, the pressure changes obviously after the blocking plate, and the influence of the simulated shock wave reflection on the flame is limited.