航速对舰船气泡尾流几何特性的影响

为了了解航速对舰船气泡尾流几何特性的影响,探索不同尺度的气泡在尾流中的作用规律,为气泡尾流的声探测以及鱼雷的尾流自导提供理论依据,该文采用抛物化的雷诺平均纳维斯托克斯（PRaNS）方程、气泡输运方程及k-ε两方程湍流模式,对2类典型船型的远场气泡尾流场进行了建模与分析,数值估算了舰船尾流中气泡数密度的分布特征,比较了不同航速下气泡尾流几何特性的差异,并与实测结果进行了比较,二者吻合得较好。计算结果表明,航速对气泡尾流的几何分布形状影响不大,但对尾流中气泡浓度的大小影响明显。航速越大,相同尾龄时的气泡数密度也越大,尾流特征越明显;在尾流不同尺度的气泡中,半径10μm的气泡尾流浮升角最大;半径52μm的气泡尾流浮升角最小,半径30~50μm的气泡存活时间最长,所以对气泡尾流的探测应以半径30~50μm的气泡为主。

Effect of Ship Speed on Bubble Wake Geometry Characters

In order to understand the effect of ship speed on bubble wake geometry characters, explore the effect law of different scale bubbles on wake, and provide theoretical basis for acoustic detection of ship bubble wake and torpedo wake homing, this study adopts parabolic Reynolds-averaged Navier-Stokes （PRaNS） equations, the bubble transport equation and the k-ε turbulence model are used to estimate the bubble number density distribution in ship＇s far field wakes, numerically simulates the ship bubble wake geometry characters under different speeds for two typical ships, and the results agree well with the experiments. It shows that ship speed has little effect on bubble wake geometry distribution, hut has significant effect on bubble number density in ship wakes. The faster the speed of ship, the higher the bubble number density in the ship wakes with same wake age, and the clearer the wake character. The bubbles with 10 μm radius have the largest elevation, the bubbles with 52 μm radius have the smallest elevation, and the bubbles with radius between 30 -50 μm live longest. So the wake detection should be focused on the bubbles with radius between 30 - 50 μm.