基于声场精细积分算法的潜艇流激噪声预报

建立了Suboff潜艇流场、结构场和声场耦合模型,对其水下航行时流激引起的艇体低频结构振动及水下辐射噪声进行了研究。采用CFD方法对潜艇三维流场进行非定常计算,以此得到艇体表面的脉动力,并通过数据映射将该脉动力加载到潜艇有限元模型进行响应分析。以潜艇壳体响应结果为边界条件,采用声场精细积分算法对潜艇流激引起的水下辐射噪声进行预报,该算法可对Helmholtz边界积分方程(HBIE)中的弱奇异积分系数及近场积分系数进行自适应求解,当细化步数达到6时,积分以10-4的残差单调收敛。结果表明,流激作用下,潜艇水下辐射声功率及声辐射效率皆出现明显峰值,其中流激的线谱成份引起艇体受激强迫振动,辐射较强水声,宽带谱成份则引起艇体结构共振,可辐射更强的水声。因此,降低潜艇的流激噪声,需同时优化艇体型线及内部结构以改善伴流,降低湍流强度,重点是避免流激共振。

Flow-excited submarine structure acoustic prediction based on a refined integral algorithm

Based on the coupling CFD/BEM/FEM model of the Suboff submarine,the flow-excited submarine low-frequency vibration and underwater radiated noise were studied.Firstly,the transient flow of the submarine 3D fluid field was calculated via CFD tool,and the fluctuated exciting forces on submarine hull were abstracted and loaded onto the FE model via data projection for harmonic analysis.Then the flow-excited noise was calculated via a refined integration algorithm of sound field with the hull responses boundary condition.In this algorithm,the singular and near-field integral coefficients in HBIE were calculated via a self-adaptive quadrature scheme until converged at the error of 10^-4 when the refined level up to 6.Results show that,both the sound power and sound radiation efficiency appear distinct peak value,and the line spectrum of the flow excitation induces hull compulsive vibration and enlarge underwater noise,while band spectrum induces structure resonance and stronger underwater noise.So,to reduce the flow-excited hull radiated noise,both the shape of the hull and its interior structures should be optimally designed to improve the wake of the hull and reduce the turbulent intensity,and the key point is to avoid resonance.