无轴泵喷叶片流激共振产生机理及其抑制

Generation mechanism and noise suppression for the flow-excited resonance of shaftless pumpjet impellers

针对无轴泵喷异常高频梳状线谱噪声,本文研究了梳状线谱的产生原因及其噪声抑制特点。基于推进器实测噪声谱、振动谱梳状特征,初步定位梳状线谱与泵喷叶轮密切相关;进一步采用单向流固耦合分析方法,验证了无轴泵喷高频线谱来源于流激引起的叶轮面内2弯模态共振,并提出了一种在叶轮过流通道增设环筋以提高叶片支撑刚度的方案。流固耦合仿真及实测结果表明:带有环筋加强的泵喷叶轮对流激振动与噪声有明显抑制作用,梳状线谱噪声降幅达25.2~30.2 dB,且未向其他频段转移。

To cope with abnormal shaftless pumpjet noise with a high-frequency comb spectrum,we studied the cause and noise suppression characteristics of such a comb spectrum.First,by analyzing the comb spectrum of the radiated noise and the direction pattern of the thruster vibration,the source of the comb spectrum was confirmed to be closely related to the pumpjet impeller.Second,a one-way fluid-structure coupling analysis verified that the ab-normal spectrum at high frequency was generated by the two-bend in-plane bending modal resonance of the impeller because of flow excitation.Third,a scheme for welding a circular plate in the impeller passages was chosen to strengthen the blade.The results from fluid-structure interaction analysis and experimental measurement show that the sound and vibration levels of a shaftless pumpjet with a strengthened impeller were considerably reduced,and the abnormal comb spectrum was suppressed.Compared with the original design,the noise level was reduced from 25.2 to 30.2 dB at different frequencies,and no noise transfer to another frequency range was observed.