隔离墙作用下欠膨胀射流氢气点火爆炸的实验研究

Experimental study on the effect of barrier wall on under expanded hydrogen jet ignition and explosion

为了降低欠膨胀射流氢气点火爆炸的危险性,通过改变隔离墙与喷嘴间距离、隔离墙长度,开展欠膨胀射流氢气点火爆炸时火焰行为和超压变化规律的实验研究。采用高速相机拍摄火焰形态,采用压力传感器测量超压。结果表明:在点火爆炸初期,火焰前锋在点火位置以扇形向外扩散;随后受射流影响,逐渐演变成三角形;火焰前锋到达墙面后逐渐熄灭;形成的射流火焰沿墙体向上、下2个方向铺展且速度基本一致;墙体长度为70cm时即可有效防止火焰向墙后蔓延;爆炸受隔离墙和地面影响,超压出现3个峰值;随着隔离墙与喷嘴间距离的增加,第一超压峰值在一定范围内波动,第二超压峰值逐渐减小;随着墙体长度的增加,最大超压呈现先增大后减小的趋势。

For alleviatingthe hazards of underexpanded hydrogen jet ignition and explosion,the flame behaviors and overpressure evolutions were investigated experimentally by changing the distance between barrier wall and nozzle,as well as the length of barrier wall.The results show that at the initial stage of ignition and explosion,the flame front spreads outwards in a flabelliform shape at the ignition position.Affected by the jet,a triangular flame front is gradually evolved.The flame front is quenched when it reaches the wall.Finally,the jet flame gradually forms and spreads over the wall.The jet flame spreads upward and downward along the wall and those speeds are almost same.When the length of wall is 70cm,the flame can be effectively prevented from spreading behind the wall.The explosion is affected by the wall and the ground,resulting in three peaks of overpressure.As the distance between the wall and the nozzle increases,the first overpressure peak fluctuates within a certain range,while the second overpressure peak gradually decreases.As the length of wall increases,the maximum overpressure shows a tendency of first increasing and then decreasing.