水下弹体空化流动的数值模拟

Numerical simulation of cavitation flow field for under water projectile

采用均质流模型对水下弹体的空化流动进行了数值模拟,控制方程的求解采用有限体积法,对流项采用迎风通量差分格式,时间步的推进则采用了LU-SGS隐式方法.使用质量传输模型模拟汽-液之间的质量转换.为了更好的计算低速流动,在计算中对对流项进行了预处理,并对质量传输源项进行了点隐式处理.对绕圆柱钝头体空化流动进行了模拟,雷诺数Re=136 000,计算得到了圆柱形钝头体在空化数σ=0.1,0.2,0.3时的壁面压力系数,并与试验结果进行了对比,符合良好.在此基础上研究了弹体带尾迹的超空化现象,空化数σ=0.2,0.1,0.06,在σ=0.06下得到了水下弹体的超空化尾迹.

A homo-equilibrium model was used to compute the hydrodynamic cavitation flow field over an axisymmetric projectile by solving the incompressible Navier-Stokes equations. The governing equations were resolved in a finite volume manner, the convective fluxes were treated by an upwind differencing scheme and the time was integrated using the LU-SGS approach. A mass transfer model introduced by Kunz was implemented in a viscous Navier-Stokes solver. A preconditioning method was used for the low-speed computations and the point implicit method for the mass transfer source terms. The computations were performed for the cavitati- on flow of an axisymmetric projectile under the Reynold number of 136 000 and the cavitation number of 0.1, 0.2 and 0.3. The wall pressure coefficients on the axisymmetric projectile were obtained and compared with experimental data, the agreements were excellent. And then, the super-cavitation phenomena were studied for v= 0. 2 ,0.1,0. 06 , and the super-cavitation flow-field was obtained for cavitation number v=0.06.