鼓泡塔中驻波声场调制大气泡的直接模拟

采用直接数值模拟的方法，同时计笋了鼓泡塔中高频驻波的生成、传播和一个直径5．55mm的大气泡与该驻波相互影响的行为．气液主流场采用考虑表面张力的粘性可压缩流体动力学基本方程和气液两相的状态方程来描述，可压缩气泡的界面行为由Levelset方法耦合界面作用模型来处理，驻波声场通过与时间相关的传感器速度入口边界条件形成．模拟结果显示，反应器中形成了一个稳定的驻波声场；由于气泡的存在，均匀的压力场变成了轴对称分布的压力场；气泡容积以很小的振幅周期性收缩与膨胀．模拟结果还揭示了对于在驻波声场中的大尺寸气泡，Bjerknes力与浮力之比为20％-25％，与实验结果21％基本相符．

Direct simulation of a Large Bubble Modulation with an Acoustic Standing Wave in a Bubble Column

A direct numerical simulation is carried out to calculate the generation and propagation of acoustic wave with a high frequency and the interaction between a 5.55mm large bubble and the acoustic field in a bubble column at the same time. In the simulation, the flow of gas and liquid phases is governed by the compressible hydrodynamic conservation equations including surface tension with the equations of state for two phases. The interface behavior of a compressible gas bubble is treated by the Level-set method coupled with the interface interaction model. An acoustic standing wave is formed in bubble column under the transducer boundary condition of a time dependent velocity inlet. The simulated results show that a stable acoustic standing wave is formed in bubble column and the uniform pressure field is replaced by an axially symmetric pressure distribution in the presence of the bubble. The bubble contracts and expands at small amplitude. The simulation reveals a value of the ratio of the Bjerknes force to the buoyancy force for a single large bubble rising in the acoustic field to be at 20%-25%, close to the experimental value 21%.