Experimental Study of External Flame Evolution and Temperature Characteristics after a Methane Explosion in a Rectangular Chamber

[Image: see text] A series of methane-vented explosions were experimentally investigated in a 4.5 m(3) rectangular chamber at P(0) = 100 kPa and T(0) = 298 K, and the effects of ignition positions and vent areas on the external flame and temperature characteristics were studied. The results indicate that the vent area and ignition position significantly affect external flame and temperature changes. The external flame is portioned into three stages: an external explosion, a violent flame jet with a blue flame, and a yellow flame venting. The temperature peak first rises and then reduces with increasing distance. Rear ignition produces the largest flame lengths and highest temperature, while front ignition leads to the shortest flame and smallest temperature peak. The maximum flame diameter occurs at central ignition. As vent areas increase, the coupling effect of the pressure wave and the internal flame front weakens and the diameter and peak of the high-temperature peak increase. These results can offer scientific guidance for designing disaster prevention measures and evaluating explosion accidents in buildings.