瓦斯爆炸数值模拟研究

Study on Numerical Simulation of Gas Explosion

对瓦斯爆炸传播进行了理论分析,并借助通用CFD软件模拟了点火源球形压力波的传播过程以及压力波的反射与相交;模拟了直管道以及变截面管道压力波传播过程。发现在压力波的相交处会出现局部高压,而压力波的不断叠加使弱压缩波成为激波。前驱冲击波会随着不断传播而逐渐衰竭,当火焰阵面追上前驱冲击波阵面达到同步时,会形成爆轰波,而爆轰波的压力值与传播速度均有大幅提高。还验证了在截面积突然缩小时,火焰传播的最大速度不在截面突然缩小处,而是向后推移了一段距离;这是因为最大湍流度不是在截面突然缩小处,而是向后推移至某一断面,这也反映了湍流对瓦斯爆炸传播的影响。通过数值模拟也发现通用CFD软件在计算爆炸场时,其收敛性与稳定性方面仍然有待提高。

In this paper,theoretical analysis on gas explosion propagation was carried out.The propagation process of ignition source sphere pressure wave and the reflection and superimposition of pressure wave were stimulated with the aid of the universal CFD software.The propagation process of pressure wave in straight pipeline and cross-section-variable pipeline was also stimulated.It was found that partial high pressure appeared in the intersect region of the pressure wave and the unceasing superimposition of pressure wave made the weak compressive wave becoming shock wave.The fore-shock wave gradually crocked up with its propagation and formed detonation wave when flame surface caught up the fore-shock wave surface and achieved synchronization,and the pressure value and propagation velocity of detonation wave enormously increased.The maximum flame propagation velocity did not appear in the sudden-reducing section,but pushed backward a certain distance while the pipeline cross-section suddenly reduced,this is because the maximum turbulence degree did not appeared in sudden-reducing section,but pushed backward to a cross-section.This reflected the influence of turbulence function on the gas explosion propagation.It was found by numerical simulation that the astringency and stability of the universal CFD software need to be improved when it is used for computing the explosion field.