喷气推进航行体空泡流的尺度效应研究

The scale effect of natural cavitating flow and exhausted gas of an underwater vehicle

基于Reynolds平均N-S方程和Mixture模型,耦合自然空化模型,运用气、汽、液多相空泡流动的数值模拟方法,模拟了水下航行体自然空泡和尾部燃气射流发展的非定常过程。对于六种模型尺度,计算分析了自然空泡和燃气射流的尺度效应。计算结果表明:随着模型尺度减小,相应的雷诺数也缩小,水流紊动减弱,空泡的脱体点后移,航行体头部低压区范围减小,导致压差阻力系数增大。同时,雷诺数越小意味着黏性力影响越显著,相应的黏性阻力系数增大。模型缩尺对于尾部燃气射流的发展影响较小,不同尺度模型的马赫数分布与阻力系数分布基本相同。

Based on the Reynolds-Averaged N-S equations and Mixture multiphase model,coupled with the natural cavitation model,the evolution of the natural cavity and combustion gas of an underwater vehicle was solved by numerical simulation on the multiphase cavitating flow of gas,vapour and water.The scale effects on the natural cavity and combustion gas jet were analysed for six model scales.The numerical results indicates that the Reynolds number,the flow turbulence and the incipient cavitation number is falling with the decrease of model scale.As a result,the detachment point of the cavity moves backwards,the area of low pressure on the vehicle head reduces and the pressure drag coefficient increases,And the frictional drag also increases due to the enhances of viscous action.The model scale has littler infection on the combustion gas.The Mach number and pressure distribution for different model scale are very close.