考虑气泡非均匀耗散的矩形反应器声流场数值模拟及结构优化

Numerical simulation and optimization of acoustic streaming considering inhomogeneous bubble cloud dissipation in rectangular reactor

声流效应能够有效强化声反应器内的传质过程,大型声反应器中声流驱动力主要来源于声波非线性耗散。以大型壁面式声反应器作为研究对象,采用考虑气泡非均匀分布的非线性声学模型预测声场,耦合声体积力求解三维声流场分布,通过粒子图像测速技术验证模型准确性,研究了超声功率、反应器宽度和液位高度对声流效应的影响规律。结果表明,提高超声功率能够显著提升声流效果,但密集的空化气泡会产生强烈的耗散,导致空化能量的转化率降低;狭窄空间严重阻碍声流发展,反应器空间过于宽阔无益于扩大高流速区域,反而会降低整体的声流强化性能,变化曲线表明40 kHz、60 W驱动条件下能达到最优声流效果的最佳响应宽度和高度分别在200 mm和100 mm左右。

The acoustic flow effect can effectively enhance the mass transfer process in the acoustic reactor,and the driving force of the acoustic flow in the large acoustic reactor mainly comes from the nonlinear dissipation of acoustic waves.A nonlinear acoustic model combined with non-uniform bubbles distribution was employed to predict the acoustic field in a bath-type scale-upsonoreactor.Volume force was coupled with the acoustic field to predict the three-dimension acoustic streaming field.The accuracy of the numerical model was verified through particle image velocimetry.The influence of ultrasonic power,reactor width,and liquid level on acoustic streaming was studied.The results show that while increasing ultrasonic power improved acoustic streaming,it also intensified dissipation,reducing the conversion rate of cavitation energy.The narrow space seriously hinders the development of acoustic flow.While oversized reactor is not conducive to high velocity region volume,but even degrades performance of acoustic streaming effect.The variation curves indicate that under an ultrasonic input of 60 W at 40 kHz,the optimal reactor size and liquid level are about 200 mm and 100 mm,respectively.