Inhibition effect and mechanism of ultra-fine water mist on CH4/air detonation: Quantitative research based on CFD technology

Abstract

As an effective depressant, ultra-fine water mist has broad application prospects in reducing the loss caused by a gas detonation. Ultra-fine water mist can be sprayed into coal mine roadways or natural gas pipelines when detecting the radiation spectrum signal of the explosion, to prevent further expansion of the explosion. A two-dimensional pipeline model was designed to study the effect and mechanism of methane detonation suppression by monodisperse ultra-fine water mist with a diameter of 10 μm. The methane detonation at the stoichiometric concentration (9.5 %) will decay to a deflagration under the suppression of fine water mist of 160 g/m3. When the concentration of fine water mist is less than 160 g/m3, the detonation wave has a slight attenuation in the water mist area, while it returns to a stable detonation state after passing through the mist area. The results also indicate that a water mist above 800 g/m3 can effectively suppress detonation and eventually lead to flame extinguishment. The critical transition concentration of ultra-fine water mist that can decay a methane detonation to a deflagration and the critical extinction concentration of ultra-fine water mist that completely suppresses a detonation within the explosion limit were obtained, providing a visual reference for the suppression of methane explosion accidents in coal mine tunnels or pipelines.