水力空化气液混溶器中空化流场的数值模拟研究

Numerical Investigation of Cavitating Flow in A Hydrodynamic Cavitation Gas-liquid Reactor

采用二维轴对称模型,对船舶压舱水和饮用水处理装置中应用的水力空化气液混溶器的空化流场进行了数值模拟,研究了不同压力比值条件下,空化数、流量系数、含气率和气相质量交换率变化及分布情况.研究结果表明：当压力比值小于等于0. 7时,水力空化气液混溶器中能够产生稳定的空化现象.空化发生时,流量稳定,不受压力比值变化影响.在空化流动中,含气率呈现振荡状态并逐渐趋于某一稳定值.仅当压力比值为0. 2时,含气率呈周期性振荡.空化溃灭总是发生在尾流区域,因此水力空化水处理过程主要发生在空化泡尾流区域.研究结果为船舶压舱水和饮用水处理装置高级氧化工艺优化和设计提供了技术参考.

The flow characteristics were simulated and analyzed with two-dimensional axial model for a cavitation gas-liquid reactor applied in ballast water and drinking water treatment system. The change and distribution of cavitation number,flow coefficient,volume fraction and mass exchange rate were investigated under various pressure ratios. Simulation results indicate that the cavitation phenomenon occurred when the pressure ratio was smaller than 0. 7,meanwhile the flow coefficient became constant and independent on pressure ratio. In cavitation flow field,the vapor volume fraction became stable after the initial oscillation. Only when the pressure ratio is 0. 2,the vapor volume fraction exhibited periodic oscillation. The cavitation bubbles always collapsed in the wake region,in where the effect of hydrodynamic cavitation on water treatment was achieved. The results can provide technical supports for the design and optimization of advanced oxidation process in the ballast water and drinking water treatment system.