煤层振荡脉冲流场数值模拟研究

Study on Numerical Simulation of Coal Ceam Oscillating Pulsed Flow Fiel

振荡脉冲流具有强大的破坏力,可将其应用于低渗透煤层强化水力增透效果。理论分析表明流体初始扰动频率f与腔体内自激振荡脉冲频率相同,如果腔体内自激振荡脉冲频率与腔室固定频率成倍数关系,则喷嘴与射流将发生共振现象,从而使得振荡脉冲效果最优。数值模拟分析了脉冲腔内的不同工况条件下的水压分布规律,同时得出振荡器腔体内会形成关于水射流中轴线对称的巨大的空化气囊,振荡器产生的这种断续涡环流结构会使得射流效果远远高于普通射流。

Oscillating pulsed flow has strong destructive power,and can be applied to enhance hydraulic permeability in low permeability coal seam. The theoretical analysis shows that the initial disturbance frequency of the fluid is the same as that of the self-excited oscillation pulse in the cavity. If the frequency of the self-excited oscillation pulse in the cavity is multiplied by the fixed frequency of the cavity,the resonance between the nozzle and the jet will occur,so that the effect of the oscillation pulse is optimal. The distribution of water pressure in the pulse chamber under different working conditions is analyzed by numerical simulation. At the same time,it is concluded that a huge cavitation air bag with symmetrical axis in the water jet will be formed in the oscillator chamber. The intermittent eddy circulation structure produced by the oscillator will make the jet effect much higher than that of the ordinary jet.