Experimental study on gas explosions of methane-air mixtures in a full-scale residence building

The field tests were carried out in a full-scale residence building with volume of 105 m(3) to reveal the hazards and mechanism of methane-air mixture explosions. The real layout and variations of gas concentration, initial state and ignition position are considered in the explosion tests. The pressure-time histories and flame development of each test were recorded and analyzed. The concentration distribution was also measured by using the fixed concentration sensors and mobile robots. It is found that when the methane diffuses freely in the resident buildings, concentration stratification can be observed in the vertical direction and the concentration of region with height of 0.64 similar to 2.38 m is within the explosive limit in the 9.5 vol% case. In the real scenario, the maximum overpressure of gas explosions in residence buildings is less than 10 kPa due to the effective venting of doors and windows. The concentration of 9.5 vol%, uniform gas distribution and ignition position in room 2 can bring about more intensive gas explosions and in turn result in higher overpressure loads and stronger external flame propagation. What is more, the acoustic oscillation is significantly restrained by the disturbance on the acoustic field caused by the effective venting, gas stratification and obstacle distribution in residence buildings.