水下航行体首部边界层转捩噪声源定位研究

Research on localization of noise sourcesin boundary layer transition at the bow of underwater vehicle

为研究水下航行体首部边界层转捩区的噪声特性及声源位置,本文采用缩比SUBOFF模型在高速水洞中开展了试验研究。水洞试验段来流速度为3~7 m/s,基于模型长度的雷诺数为10^(7)量级,首部表面布置14支脉动压力传感器,测量了首部层流边界层、转捩和湍流边界层的脉动压力场。为定位声源位置,采用传声器阵列进行了水下航行体首部主要噪声源的三维声源定位,定位方法为基于小波变换的函数波束形成方法。试验结果表明:随着来流速度增大,首部边界层转捩起始位置不断向前移动,同时脉动压力频谱中的中频分量显著增加。声源定位结果表明:水下航行体首部主要噪声源呈三维环形分布,且声源所在流向位置与边界层转捩区位置基本重合,表明边界层转捩区是水下航行体首部的主要噪声源。

The boundary layer transition at the bow of an underwater vehicle(UV)is one ofthe major sources of the fairing self-noise.To study the noise characteristics of the boundary layertransition at the bow of UV and the sound source locations,a scaled SUBOFF model was adoptedfor the experimental study in a high-speed water tunnel.The inflow velocity of the water tunneltest section was 3–7 m/s,and the Reynolds number based on the model length was about 10^(7).Inaddition,fourteen dynamic pressure sensors were arranged on the bow surface to measure thefluctuating pressure field within the region of laminar,transition and turbulent boundary layers.A phased microphone array was employed to locate the three-dimensional sound source at thebow of SUBOFF.The localization method adopts a functional beamforming method based ontime-frequency transformation.The experimental results demonstrate that the transition position of the bow boundary layer moves forward synchronously with the increase of the incoming flowspeed.Meanwhile,the amplitude of the mid-frequency component of the fluctuating pressurespectrum significantly rise.Furthermore,the results of sound source location show that the three-dimensional sound source presents a ring shape,and the streamwise position of the sound sourcealmost coincides with the transition position of the boundary layer.This indicates that thetransition region of the boundary layer is the main noise source in the bow region of theunderwater vehicle.