开口型管道内瓦斯爆炸冲击波动压的数值模拟

Simulation on dynamic pressure of premixed methane/air explosion in open-end pipes

为了研究瓦斯爆炸冲击波的动压演化规律,利用数值模拟软件模拟开口型管道内的爆炸。结果表明:动压与流速在时间上存在较好的对应关系,基本同时出现正向和反向的峰值;动压在3个方向上不仅伴随传播距离的增大而不断增大,也伴随传播时间的延长而增大;沿管道方向(火焰传播方向)上的最大动压值是其他2个方向(管道径向)上的数千倍;相比爆炸超压而言,管道径向上的动压对爆炸破坏效应的影响较小,而沿管道方向上的动压造成的破坏效应不能忽视;验证了动压与流速的平方呈正比关系,同时通过分析给出了动压基于管道几何尺寸和流速的经验公式。

In order to study the evolution of dynamic overpressure of deflagration, a simulation was carried out in an open end pipe. It was found that the dynamic pressure was closely correlated with the gas velocity so that they always arrive at the peak value at the same time. In addition, the first posi- tive peak of the dynamic pressure was almost several times greater than that of the second. This may indicate that the blast wave has a greater influence on the dynamic pressure than the flame does. An empirical prediction equation was given to calculate the first and second positive peaks based on the propagation time. Maximum dynamic pressures were increased with the propagation distance in all the three directions （x, y and z）, and so was with time. The maximum dynamic pressure value in the x direction was almost several thousand times greater than those in the other two directions. Compared with the explosive overpressure, the influence on the explosive damage by the dynamic pressure in the y and z direction was quite small. Three empirical formulas were given to calculate the maximum dy- namic pressures in different directions. The relationship between the dynamic pressure and the square of the gas velocity was verified. An empirical formula of the dynamic overpressure was also given based on the length-diameter ratio and the gas velocity. The results may provide a reference for the study on the gas explosion in the limited Spaces.