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为了研究发动机水下排气气泡运动特性,从工程应用问题出发,分析气泡水下运动及演化特性.考虑重力、浮力、黏性阻力及表面张力作用,运用VOF(流体体积法)方法对气液两相界面进行追踪,对单气泡运动特性进行模拟计算,提出一种计算气泡形心坐标、运动轨迹、速度大小的方法;基于对菲克定律中扩散通量的求解模拟了单气泡在水中的溶解特性.结果表明:气泡在水下上升过程中底部持续向内凹陷,形状由球形变为扁椭球形或帽形;单气泡在水中的运动轨迹初始为直线,随后开始左右摆动上升,摆动幅度逐渐变大,为类S曲线;x方向速度从零开始增大,并在Vx=0这条直线上下波动,幅度逐渐增大;y方向速度经历了由零到快速增长、近似恒定、急剧减小的过程.
In order to study the motion characteristics of bubbles in underwater exhaust of engine, the bubble underwater motion and evolution characteristics are analyzed from the engineering application.Considering the effect of gravity, buoyancy, viscous resistance and surface tension, Two-phase interface is traced to simulate the movement characteristics of single bubble. A new method to calculate bubble centroid coordinate, motion trajectory and velocity is proposed. Based on Fick’s law, the diffusion flux is simulated to simulate the single bubble in water The results show that the bottom of the bubble continues to be inwardly concave and the shape changes from spherical to oblate ellipsoid or hat shape. The movement of single bubble in water is initially straight and then begins to swing left and right, Gradually become larger, which is the S-shaped curve. The velocity in x direction increases from zero and fluctuates upward and downward at the straight line Vx = 0, and the amplitude increases gradually. The velocity in y direction goes through zero to rapid growth, Small process.