限制式与非限制式结构雾化气体动力学分析

Dynamic analysis on atomized gas in limited and unlimited structures

针对两种典型雾化结构:限制式和非限制式结构,对其各自的雾化气体流场进行了数值模拟.根据模拟结果,分析了两种结构雾化器气体流场的分布情况及轴线处各参数变化规律,并通过对比指出了两种结构气体行为的同异之处.结果表明:两种结构均能形成回流区,但回流区形貌不同,且限制式结构回流强度更高,回流区温度降低更明显;回流区的下方存在一个速度为0的滞止点,但滞止点并非气场中压力最大值点,压力最大值点在滞止点的下方区域,是射流中心主流的交汇点.在喷射过程中,雾化气流会以振荡形式运动,限制式结构气流振荡幅度较大,随喷射距离增加,气流的振荡减弱.

The numerical simulation for the flow field of atomized gas in two typical atomizing structures,namely limited and unlimited structures,was performed.According to the simulation results,the distribution of atomization gas flow field in two structures and the change rule of individual parameter on the axial line were analyzed.In addition,the same and different points of gas behavior in two structures were pointed out through performing the comparison.The results show that the backflow regions can form in two structures,but the morphologies of backflow regions are different.Moreover,the backflow strength in the limited structure is higher,and the decrease in the temperature of backflow region is more obvious.A stagnation point with zero velocity appears below the backflow region,but is not the maximum pressure point in the gas field.The maximum pressure point locates at the region below the stagnation point,and is the convergent point of main flow at the jet-flow center.In the spaying process,the atomized gas flow will move in an oscillation mode,and the oscillation amplitude of the gas flow in the limited structure is bigger.With increasing the spaying distance,the oscillation of the gas flow weakens.