鼓泡床中超声驻波的模拟及其对气泡的调制机理

采用计算流体动力学（CFD）的方法，数值生成了鼓泡床中一对声换能器以16kHz高频振动引发的超声场。数值计算是基于包括粘性影响的可压缩流体基本守恒方程，并耦合了水的状态方程。模拟结果表明，在本研究所用的几何布置和换能器与时间相关的速度入口边界条件下，反应器中形成了一个稳定的驻波声场；由于波的非线性以及水的粘性，压力波节点呈现出轻微的时间漂移性。模拟结果与前人的实验结果定性吻合。在模拟的声压分布的基础上，分析了驻波声场调制气泡的机理。如比较熟知，气泡在驻波声场作用下或者向压力波节点运动或者向压力波腹点运动，取决于气泡尺寸与共振尺寸的关系。

Simulation of ultrasonic standing wave in a bubble column and mechanism for its bubble modulation

A computational simulation is carried out to generate the acoustic standing wave induced by a pair of acoustic transducers oscillating with frequency of 16kHz in a bubble column by means of CFD method. The numerical simulation is based on the fundamental hydrodynamic conservation equations including viscous effects for compressible fluid, coupled with the equation of state for water. The simulated results show that a stable acoustic standing wave is formed in bubble column under the geometric arrangements and the transducer boundary condition employed in this study. Due to the nonlinear behavior of the resonant wave and viscosity of water, there is a temporal shift at pressure nodes. The simulation results agree with the experimental ones qualitatively Based on the distribution of sound pressure, the mechanism for bubble modulation is analyzed. A gas bubble moves towards either the pressure node or the pressure anti-node, depending on the relation between the bubble actual size and its resonant size.