水雾粒径对超细水雾抑制甲烷/空气爆炸过程的影响

Effect of droplet size on the inhibition of methane/air explosion process by ultrafine water mist

建立了超细水雾作用下甲烷-空气爆炸过程的三维数值模型,采用大涡模拟模型计算爆炸流场瞬态流动过程;考虑了水雾的蒸发、汽化过程以及气液两相间的质量、动量和热量交换,通过欧拉-拉格朗日模型分别对连续相与离散相进行计算,交替求解离散相与连续相的控制方程实现气液两相间的耦合求解;分析了水雾粒径对爆炸火焰反应区作用程度以及热量交换速率的影响;获得了最佳抑爆粒径并解释了粒径导致抑爆效果差异的原因;水雾粒径通过与火焰反应区的作用程度和蒸发速率影响气液两相间的热量交换速率,进而影响火焰传播速率和爆炸强度;为实现爆炸强度的有效抑制,水雾粒径选取的条件应保证水雾在反应区完全汽化。

Three dimensional numerical model of methane-air explosion was established by using the large eddy simulation model.The processes of water mist evaporation and vaporization and the exchanges of the mass,momentum and heat between the gas and liquid phases were considered. The continuous phase and discrete phase were calculated through the Euler-Lagrange model respectively and alternately solving two phases control equation to realize the gasliquid two phases coupling solution.The effects of the mist size on the interaction extent and the heat exchange rate of explosion reaction zone were analyzed,and the optimum size for explosion suppression was obtained and the reason of the suppression effect difference was explained respectively. The effect of mist size on gas-liquid two phase heat exchange rate was affected through the interaction extent of the flame reaction zone,the droplet and the evaporation rate;thereby the flame propagation speed and explosion intensity were affected obviously.The condition of mist size selection was that the mist should be completely vaporized in the reaction zone in order to effectively realize explosion suppression.