空化模型在低温流体空化流动三维计算中的应用与评价

Evaluation of cavitation model in three-dimensional computations of cryogenics liquid cavitating flows

为评价不同空化模型对低温流体空化过程流场特性预测的适用性,文章通过对CFX软件的二次开发,将Kubota、Merkle和Kunz三种空化模型和液氮、液氢随温度变化的物性参数引入到CFX求解代码中,同时在求解的能量方程中添加汽化潜热影响,从而在考虑热力学效应条件下,开展了液氮绕水翼空化流动和尖顶拱在液氢中空化流动的三维数值模拟研究,并将计算结果与试验数据进行对比,实现了对不同空化模型适用性的评价。结果表明:三种空化模型计算的空化区域液相分布特性不同,空泡长度和厚度有差别;由于空化模型方程源相体现的质量传输机理不同,导致热力学效应下空化区域压强分布和温降存在差异;Kubota空化模型可有效预测液氮空化流场压强分布,Merkle模型可较好地反映空化区域温降,Kunz模型计算的结果与试验数据差别最大。

This paper aims to evaluate the application of different cavitation models in three-dimensional computations of the cavitating flow characteristics of cryogenics liquids.The aim is realized by implanting the cavitation models and physical properties of liquid nitrogen and liquid hydrogen at different temperatures to the CFX solver code by using the secondary development of CFX software,and considering the effect of latent heat of evaporation in the energy equation,then the 3 D numerical simulation of cavitating flow is conducted around a hydrofoil in liquid nitrogen and ogive in liquid hydrogen.The results show that the liquid phase distribution characteristics of the three different cavitation models at the cavitation region are different,and the length and thickness of the cavity have some differences.Due to the difference of the mass transfer mechanism of the three cavitation models,which leads to the pressure distribution and temperature drop are different under the thermodynamic effects.The applicability of Kubota model is the strongest for predicting the pressure distribution,and the Merkle model can reflect the temperature drop at the cavitation region well,whereas the differences between the numerical results and experimental data of Kunz model are the biggest.