基于扇声源理论的螺旋桨负载噪声频域预报

Predicting Loading Noise of Propeller Based on Fan

关键词:  螺旋桨  负载噪声  扇声源理论  边界元法  计算流体力学

Key words:  Propeller  Loading noise  Fan noise theory  Boundary element method  Computational fluid dynamic

摘要:

为了准确计算螺旋桨噪声，以均匀进流条件下船用E779A螺旋桨为研究对象，采用扇声源方法结合边界元方法对螺旋桨的负载噪声进行了数值预报，研究了扇声源方法中等效偶极子不同划分方案对螺旋桨负载噪声计算精度的影响。结果表明:采用扇声源方法结合边界元方法能够准确预报螺旋桨的负载噪声，在低频处计算值与文献值相差最大不超过4dB；不同频率对应的指向性均呈现8字形分布，其中叶频和二倍叶频对应的指向性在桨轴方向声压级最大，而三倍叶频对应的指向性在径向方向声压级最大；叶片等效的旋转偶极子越多，低频噪声的计算精度越高，在叶频和二倍叶频处的计算值与文献值相差最大不超过1.2dB。

Abstract:

In order to predict propeller noise precisely，taking the marine propeller of E779A under uniform flow as object，the loading noise of propeller is numerically calculated by fan noise model in the frequency domain combined with boundary element method. The effects of different segmentations of equivalent dipole in fan noise model on computational precision of the loading noise of propeller are studied. The results show that the loading noise of propeller can be calculated accurately by fan noise model in the frequency domain combined with the boundary element method. The biggest difference between numerical results and reference results is no more than 4 dB in low frequency domain. The directivity of different frequencies present 8 shape distribution. Sound pressure level(SPL)is the biggest in axial direction for the directivity corresponding to blade passing frequency(BPF)and 2BPF，while SPL is the biggest in radial direction for the directivity corresponding to 3BPF. The more rotating equivalent dipole in one blade is，the better computational precision of low frequency noise is. The biggest difference between numerical results and reference results in BPF and 2BPF is no more than 1.2 dB.