通气空泡流中洞壁效应对空化数和压力场影响的研究

文章在均质平衡多相流模型的基础上耦合输运方程型空化模型,通过求解混合介质的RANS方程、RNG k-ε湍流输运方程以及各相的质量输运方程,采用通用CFD软件—FLUENT数值模拟了水洞中带圆盘空化器航行体模型的定常通气空泡流动,研究了圆形截面闭式空泡水洞中洞壁效应对通气空化数和压力场的影响。得到的阻塞空化数线性正比于圆盘水洞直径比,且与三维圆盘自然空泡流的势流近似解基本一致,分析了洞壁效应作用下空化流场内的压力分布特点,并根据计算结果拟合了一定适用条件下通气空泡长度、最大直径和模型阻力系数的近似公式。

Investigation for influence of wall effects on cavitation number and pressure field of ventilated cavitating flows

A natural cavitation model was coupled with the isotropic mixture multiphase model.By solving the RANS equations,RNG k-ε turbulence transport equtations of the mixture and the mass transtport equations of each phase,steady ventilated cavitating flows were simulated in round-section water tunnels for a given underwater vehicle model with a disk cavitator using universal CFD code-FLUENT.The influence of wall effects on the cavitation number and pressure field of ventilated cavitating flows was investagated in closed water tunnels.The gained blocking cavitation number is in direct proportion to the diameter ratio of the disk to the water tunnel,and it was close to the potential solution for a 3D disk in natural cavitating flows.The characteristic of the pressure distribution was studied in ventilated cavitating flowfields under the action of wall effects.According to computational data several approximate formulas in a certain range of validity were put forward for the length and maximum diameter of the ventilated cavity as well as the drag coefficient of the model.