Dimensional study of flexible protection device based on methane explosion protection mechanism

Flexible materials deform during flame propagation, altering their blockage ratio and the force exerted on the fluid due to various influencing factors. This affects gas explosion characteristics, changes the flame structure, and reduces explosion overpressure and flame speed. To determine the impact of flexible protective devices on the protection mechanism against gas explosions, this experiment used flexible obstacles (polyurethane sponge) as the protective apparatus. Employing a self-built explosion experiment platform, the research investigated methane explosion flame evolution, flame propagation speed, and explosion overpressure under various sizes of pre-positioned flexible obstacles. The study focused on observing the morphological evolution of methane explosion flames, the speed of flame spread, and the explosion overpressure in scenarios with pre-positioned obstacles of different sizes. The results showed that inserting flexible obstacles effectively reduced explosion overpressure and flame front propagation speed. Based on the working conditions set up in this experiment, the maximum rate of decrease in explosion overpressure exceeds 50% and the maximum rate of decrease in flame front velocity is around 20%. With pre-positioned flexible obstacles, as the blockage ratio of the flexible obstacle increased, the severity of deflagration also increased, with both explosion overpressure and flame front speed rising with the blockage ratio. Explosion overpressure and flame front speed also increased with the thickness of the flexible obstacle; simultaneously, the flame front position advanced with the thickness of the flexible obstacle. When constructing close-range protection devices, the height of the protection device should be lower than the protected object (H < h), and the thickness of the protection device should not be too thick.