鱼雷发射管跟随流体射流噪声的数值计算

Numerical research on jet flow noise induced by torpedo tube exit flow

为了定量分析鱼雷出管后形成的瞬态射流噪声在总的发射噪声中的贡献程度,采用计算流体力学和计算声学相结合的混合模拟方法对两种速度下的定常射流噪声进行了预报和分析.射流噪声模拟时考虑艇体壁面限定影响,湍流涡捕捉采用大涡模拟方法,声传播计算采用边界元数值声学方法.结果表明:射流束集中穿过艇体壁面上的防波板出口,仅有少数流体在发射水舱内折转涌动;艇体壁面存在破坏了发射水舱内射流束与周围流体之间剪切层的形成,艇体壁面外湍流涡结构与射流混合区理论形状一致;射流噪声主要贡献频带位于100Hz以内和300Hz^1kHz范围内,且以低频段为主;偏离射流轴向方向时,辐射噪声显著减小;电磁式鱼雷发射装置的声学优化空间显著.

To obtain deep insight into the contribution of transient jet flow noise on overall launching noise of torpedo,the numerical predictions of underwater jet flow noise with two constant velocities were addressed by using computational fluid dynamics-computational acoustics weak coupling method.The effect of submarine hull on limiting the jet flow field evolution was included into computational fluid dynamics calculation.Large eddy simulation was used to simulate the turbulent vortex structures,following which,the boundary element numerical acoustics method was used to calculate the sound propagation in frequency domain.Results show that potential core of jet flow mainly goes straight through the inflatable wall exit on submarine hull,and only a little of streamline turns around within this process.The turbulent shear layer developed from interactions of jet flow core and the ambient water is suppressed in launching water tank due to submarine hull exist.The captured turbulent vortex structure outside submarine hull is consistent with the theoretical shape of jet mixing region.The jet flow noise mainly concentrates in frequency band within 100 Hz and 300Hz^1kHz,and the low frequency contribution is obvious.The radiated noise decreases with far away from the axial direction.The small jet flow noise caused by the followed water behind torpedo hull presents a tremendous scope for sound performance improvement of torpedo launching equipment by electromagnetic launcher.