PPTC螺旋桨空化噪声特性及空化发声机理的数值研究

Numerical investigation of PPTC propeller cavitation noise characteristics and sound generation mechanism

  • 摘要:
    目的 旨在有效抑制螺旋桨空化噪声,研究螺旋桨空化噪声特性及空化发声机理。
    方法 基于大涡模拟(LES)与可渗透的FW-H (PFW-H)方程远场解相结合的方法,对PPTC螺旋桨空化流场和声场进行高精度仿真,重点研究空化对远场噪声频谱分布特性的影响及其发声机制。
    结果 模拟的水动力场结果与试验数据吻合较好。研究发现,螺旋桨周围片空化(SC)和梢涡空化(TVC)的演变过程均存在显著的周期性特征,均贡献了高强度的主频噪声。其中,片空化的初生和溃灭演变过程伴随着高强度的瞬时空化体积变化,导致高频宽带噪声加剧;梢涡空化演变时出现体积回弹行为,诱发了高强度的连续声压脉动,导致在高于主频的频率处产生显著的噪声峰值。
    结论 研究结果可为工程中螺旋桨空化噪声控制策略的提出和实现提供理论依据。

     

    Abstract:
    Objectives Cavitation, as one of the most important noise sources around propellers, significantly enhances far-field radiated noise and brings many adverse effects. To effectively suppress propeller cavitation noise, it is necessary to carry out research on its noise characteristics and sound generation mechanism.
    Method In this study, the cavitation noise around a PPTC propeller is simulated using a large eddy simulation (LES) combined with the permeable Ffowcs Williams and Hawkings (PFW-H) equation, focusing on the effect of cavitation on the spectral characteristics of far-field noise and the cavitation noise generation mechanism.
    Results The predicted hydrodynamic results agree well with the experimental data. It is found that there is a significant periodicity in the evolution of both the sheet cavity (SC) and tip vortex cavity (TVC) around the propeller, thus both contribute high intensity dominant frequency noise. SC evolves with incipient and collapsing processes which are accompanied by transient cavity volume variations, leading to an intensification of high-frequency broadband noise. TVC evolves with a volume rebound behavior which induces high-intensity continuous acoustic pressure pulsations and thus induces significant noise peaks at frequencies above the dominant frequency.
    Conclusion This paper provides a theoretical basis for the proposal and implementation of propeller cavitation noise control strategies in engineering.

     

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