The strong pressure wave in gas explosion accident could cause great casualties and property loss, which has become the main threat to safety of chemical process and further popularization of clean energy. In this research, unconfined explosion experiments under different methane concentrations at 27 m³ scale were performed with internal and external obstacles. The results showed that the flame buoyant effect was more obvious for the rich-fuel flame due to the excess methane accumulation. The reflection of the pressure wave could cause higher overpressure near the ground and the external obstacle enhanced the overpressure in the neighborhood. For 27 m³ scale explosion, the critical flame radius for the flame acceleration was larger than 1 m³ scale, because of the longer travelling distance for the reflection wave from the bottom. In addition, the acceleration exponent rose to 1.5 due to the full development of the hydrodynamic instability. The flame radius for peak overpressure, R_M, was found to be at a certain distance from the outer obstacle bar center, which was 1.8 for N_b = 6, 1.35 for N_b = 4 and 0.9 for N_b = 2. The predicted results of peak overpressure agreed well with the experimental results, which extended the prediction model to the larger scale.

瓦斯爆炸事故中的强压力波会造成巨大的人员伤亡和财产损失，已成为化工过程安全和清洁能源进一步普及的主要威胁。在本研究中，在具有内部和外部障碍物的情况下，在27 m ³规模下进行了不同甲烷浓度下的无侧限爆炸实验。结果表明，由于甲烷积累过多，富燃料火焰的火焰浮力效应更为明显。压力波的反射会导致地面附近更高的超压，而外部障碍物则增强了附近的超压。对于27 m ³规模的爆炸，火焰加速度的临界火焰半径大于1 m ³规模，因为从底部反射波的行进距离更长。此外，由于水动力不稳定性的充分发展，加速度指数上升到 1.5。火焰半径为峰值的过压，R_中号，被认为是在从外障碍物杆中心有一定的距离，这是1.8对于N _b = 6，1.35对于N _b = 4和0.9对于N _b = 2预测峰值超压结果与实验结果吻合较好，将预测模型推广到了更大规模。