Localized water mist method enabling superior premixed hydrogen-methane-air deflagration mitigation in semi-confined space

To effectively mitigate hydrogen-methane-air deflagrations in semi-confined space, we propose a Localized Water Mist (LWM) method. The results demonstrate that when the 8-μm LWM is sprayed near the igniter, the flame velocity and overpressure decrease by 38.8 % and 30.1 %, respectively. However, the 45-μm LWM exhibits enhanced effect. When the 45-μm LWM is sprayed near the obstacle, it shows superior deflagration mitigation capabilities. Reciprocally, the 8-μm LWM has few mitigation effect. Subsequently, the deflagration mitigation mechanism of LWM is analyzed. The small-diameter LWM has large surface area, sufficient interaction with the flame surface and minimal turbulence interference near the igniter. In contrast, large-diameter LWM is broken into small-size particles by the shock wave near the obstacle, which are able to enter vortex flames absorbing heat quickly. Additionally, vaporized WM mitigates deflagration by reducing the generation rate of the main radicals (OH, H, and O) through reactions R1, R3, R50, R86, R119, and R120.