收缩扩张形喷嘴内外流场的数值模拟
Numerical Simulation of Internal and External Flow Field of Contraction and Expansion Nozzle

为了探究不同工况下的收缩扩张形喷嘴对空化射流的影响，利用ICEM网格划分软件、FLUENT流体仿真软件，采用多相流模型、空化模型、可实现的湍流模型对喷嘴内外流场进行数值模拟，得出了流场中空化的分布区域，验证了空化产生的原因是由于液体中形成了局部低压，并以气泡体积分数的大小作为判断空化强弱的标准，分析入口压力、喉部直径、水深等参数对水利空化的影响，结果表明：入口压力、喉部直径、水深都对空化形成有较大影响，其中入口压力和喉部直径与空化强度呈正相关，水深与空化强度呈负相关。此次淹没环境下的空化数值模拟结果能够为其它空化喷嘴的设计提供一定的理论支持。
In order to explore the influence of contraction and expansion nozzle on cavitation jet under dif-ferent working conditions, ICEM mesh generation software and FLUENT fluid simulation software were used to simulate the flow field inside and outside the nozzle by using multiphase flow model, cavitation model and realizable turbulence model, and the distribution area of cavitation in the flow field was obtained. It was verified that the cavitation was caused by the formation of local low pressure in the liquid, and the bubble volume fraction was used as the criterion to judge the cavi-tation strength. The effects of inlet pressure, throat diameter and water depth on cavitation are analyzed. The results show that inlet pressure, throat diameter and water depth all have great in-fluence on cavitation formation, in which inlet pressure and throat diameter are positively corre-lated with cavitation intensity, while water depth is negatively correlated with cavitation intensity. The numerical simulation results of cavitation in submerged environment can provide theoretical support for the design of other cavitation nozzles.