Effect of pipe length on methane explosion in interconnected vessels

A series of experiments have been conducted to study the influence of pipe length on methane-air mixture explosion in linked vessels. Two kinds of setups, that is, a spherical vessel connected to a pipe and two spherical vessels connected by a pipe, are used. The characteristics of explosion pressure and flame propagation speed in linked vessels are obtained. The influence of flame propagation direction and the ignition position on explosion pressure and the flame propagation speed are also analyzed under different pipe lengths. The experimental results show that the maximum explosion pressure and the pressure rising rate in the secondary vessel increase with pipe length. The maximum explosion pressure and pressure rising rate increase most obviously when the small vessel is used as the secondary vessel. Moreover, the pressure oscillation is more violent. However, the primary vessel explosion pressure changes a little when pipe length changed. The flame propagation speed from the primary vessel to the secondary vessel increased with pipe length, but the flame propagation acceleration decreased with pipe length. When the pipe diameter and length is constant, bigger primary vessel causes higher initial flame propagation speed; smaller secondary vessel causes stronger blocking effect during the flame propagation.