N_(2)/超细水雾抑制甲烷爆炸点火和火焰传播特性

Inhibition effect on the ignition and flame propagation characteristic of methane explosion by N_(2)/ultrafine water mist

为了提高细水雾的抑爆效果,采用定容燃烧弹和点火能精密控制仪,通过改变N_(2)/超细水雾浓度,研究了单一抑制剂和两者共同作用对甲烷/空气爆炸最小点火能、火焰传播行为及不稳定性的影响,并采用化学动力学软件对其抑爆机理进行了探讨.结果表明:加入N_(2)/超细水雾后,甲烷/空气预混气最小点火能显著增大,爆炸超压和最大压升速率降低,压力峰值来临时间和火焰形成时间延长,火焰明显上浮,火焰胞格数量减少,马克斯坦长度增加,降低火焰传播速度的能力显著提高,说明N_(2)/超细水雾共同作用时能更好地抑制甲烷/空气爆炸初期火焰不稳定性,对火焰传播的抑制效果优于单一抑制剂,有效预防火焰加速甚至爆轰.N_(2)/超细水雾可以有效降低H·,O·,·OH等活泼自由基的生成速率峰值和摩尔分数,温度敏感性系数绝对值大幅度降低,说明二者共同作用时能有效降低预混气的爆炸敏感性和爆炸强度,有效抑制甲烷/空气预混气的点燃与爆炸链式反应的进行.

In order to improve the explosion suppression effect of water mist,the effects of a single inhibitor and their combination on the minimum ignition energy,flame propagation behavior and instability of methane/air explosion were studied by varying the N_(2)/ultrafine water mist concentration using a constant volume combustion bomb and a precise ignition energy control instrument. The explosion suppression mechanism was discussed by using chemical dynamics software. The results show that after adding N_(2)/ultra-fine water mist,the minimum ignition energy of methane/air premixed gas is significantly increased. The explosion overpressure and the maximum pressure rise rate are reduced,the arrival time of pressure peak and the time of flame formation are prolonged,the flame floats obviously,the number of flame cells are reduced,the length of Maxstein is increased,and the flame propagation speed is significantly increased,which indicating that the combination of N_(2)/ultra-fine water mist can better inhibit the flame instability at the initial stage of methane/air explosion,and the inhibition effect on flame propagation is better than that of a single inhibitor,which can effectively prevent flame acceleration and even detonation. N_(2)/ultrafine water mist can effectively reduce the peak value of production rate and molar fraction of active radicals such as H·,O·,·OH,and the absolute value of temperature sensitivity coefficient is greatly reduced,which indicating that the combination of N_(2)/ultra-fine water mist can effectively reduce the explosion sensitivity and intensity of methane/air premixed gas,and effectively inhibit the ignition of methane/air premixed gas and the process of explosive chain reaction.