圆球型声化学反应器内声场的数值模拟与实验研究

Numerical Simulation and Experimental Investigation of Ultrasound Field in the Spherical Sonochemical Reactor

利用计算流体动力学CFD商业软件-FLUENT,以多相流模型中的混合物模型(Mixture)为基础,并耦合空化模型,对自主开发研制的圆球型超声化学反应器内空化场进行了数值模拟。反应器内空化场为液态水和空化汽泡二相流动问题,研究了空化模型参数的影响,对数值模拟的结果包括超声振动时的压力场、气含率场的分布进行了分析讨论,并与声压测量实验及铝箔空蚀实验结果比较,实验数据和模拟结果基本吻合。空化模型中,不可压缩气体的质量分数越大,水中O点处的气含率越高,压强波动幅度越小;水的饱和蒸汽压越高,O点处的气含量越大,且波动幅度越大,但压强幅值变化程度越小。本项研究表明CFD技术的应用对于超声声场分析具有重要的参考价值,对声化学反应器设计理论的发展具有指导意义。

Using the mixture model and the cavitation model of FLUENT, the ultrasonic cavitation field of an independently developed spherical sonochemical reactor was simulated. The cavitation field in the reactor is a problem about the flow of two-phase fluid consisting of water and cavitating bubbles. The influences of cavitation model factors were studied, and the simulated distributions of pressure field and gas holdup field during ultrasonic vibration were analyzed and discussed. The calculated results were compared with the results of acoustic pressure measurement and the test of aluminium foil degradation, and it shows that they are basically identical. It was found that the higher the incompressible gas mass fraction is, the higher the gas holdup at point O can be, while the pressure fluctuation is smaller. Besides, when the saturated vapor pressure is higher, the gas holdup at point O is higher, and the fluctuation of gas holdup is bigger too, while the pressure amplitude is smaller. This study shows that the CFD simulation is available to be used to predict the ultrasound field, and it will be helpful for improving the design or the modification of the sonochemical reactor.