Development of a methane-air deflagration-driven blast wave simulator Ⅱ: blast wave evolution and experimental design

The design of blast wave simulators for prototype or large-scale engineering structures and components must carefully balance safety, cost, and performance. To address this challenge, a blast wave simulator driven by methane-air deflagration was developed in this study. Numerical models of methane-air deflagration in large-scale tubes were established using the CFD software OpenFOAM and validated against experimental data. On the basis of the validated model, numerical simulations were performed to investigate the effects of gas cloud length, venting conditions, and obstacle configurations on overpressure loads, thereby revealing the mechanisms of blast wave and flame propagation in the methane-air deflagration-driven simulator. A testing scheme was subsequently proposed to generate different levels of blast loading. The results show that the developed numerical model can reasonably predict the overpressure time histories and spatial distributions of gas explosions in large-scale tubes. In the simulator, increasing the gas cloud volume and placing obstacles near the ignition zone of the driven section can significantly intensify the deflagration of methane-air mixtures. Moreover, side venting effectively separates the pressure wave from the flame, thereby preventing high-temperature effects in the loading area. An optimized loading configuration was proposed, in which four obstacles (1×50% blockage ratio and 3×25% blockage ratio, spaced at 3 m intervals) were arranged, and different blast load levels were achieved by varying the gas cloud length from 1.5 m to 6 m in the driven section. Trial tests of the developed simulator showed that the measured peak overpressures agree well with the numerical predictions, with deviations less than 12%, and the results exhibit good uniformity and high repeatability. These findings demonstrate that the proposed methane-air deflagration-driven blast wave simulator is suitable for blast testing of structural components such as reinforced concrete slabs.