Explosion accidents have become the main threat for the high-efficiency use of cleaner gas energy sources, such as natural gas. During an explosion, obstacle causing flame acceleration is the main reason for the increase of the explosion overpressure, which still remains to be fully understood. In this research, field experiments were conducted in a 1 m³ cubic frame apparatus to investigate the effect of built-in obstacles on unconfined methane explosion. Cage-like obstacles were constructed using square steel rods with different cross section size. The results demonstrated that the flame could get accelerated due to the hydrodynamic instability and obstacle-induced turbulence, which enhanced the explosion overpressure. In the near field, the overpressure wave travelled slower and the maximum overpressure could almost keep constant. Reducing the cross section size, or increasing the obstacle height or the obstacle number per layer could determine the rise of the maximum overpressure, the maximum pressure rising rate and the overpressure impulse. For uniformly constructed obstacles, self-similar theory was chosen to measure the influence of the hydrodynamic instability, and a parameter β was adopted to measure the flame acceleration caused by obstacle-induced turbulence, the value of which was 2 in this research. Based on the acoustic theory, an overpressure prediction model was proposed and the predicted results agreed with the measured values better than previous models, such as TNT equivalency model and TNO multi-energy model.

爆炸事故已成为高效利用清洁气体能源（例如天然气）的主要威胁。在爆炸过程中，导致火焰加速的障碍物是爆炸超压增加的主要原因，这仍有待充分理解。在这项研究中，现场实验是在1 m ³立方框架设备，以研究内置障碍物对无限制甲烷爆炸的影响。笼状障碍物是使用具有不同横截面尺寸的方形钢棒构造的。结果表明，由于流体动力学的不稳定性和障碍物引起的湍流，火焰可以加速，从而增加了爆炸的超压。在近场中，超压波传播较慢，最大超压几乎可以保持恒定。减小横截面尺寸，或增加障碍物高度或每层障碍物数量可以确定最大超压，最大压力上升速率和超压冲量的上升。对于均匀构造的障碍物，选择自相似理论来测量流体动力失稳的影响，并使用一个参数β被用来测量由障碍物引起的湍流引起的火焰加速度，在本研究中其值为2。基于声学理论，提出了一种超压预测模型，其预测结果与实测值吻合较好，优于TNT等效模型，TNO多能模型。