基于点源模型的螺旋桨空化噪声频域预报

Prediction of propeller cavitation noise based on point source model in frequency domain

以点源模型为基础,将螺旋桨桨叶空化体积等效为旋转单极源,将旋转单极源离散为均匀分布在旋转轨迹上的有限个固定声源,结合边界元方法可以在频域内计算任意边界条件下的螺旋桨空化噪声.以4148螺旋桨为对象,在已知单个桨叶空化体积的条件下,首先基于点源模型计算了单个桨叶的空化噪声,计算结果同Ffowcs Williams-Hawkings (FW-H)方程计算结果较为相符;然后计算了整桨空化噪声,可见螺旋桨旋转效应对空化噪声的近场声指向性影响较大,对远场声指向性影响可以忽略.

Based on the point source model,the cavitation volume of single propeller blade was equivalent to a rotating monopole,and the rotating monopole was discretized into finite stationary sources distributing along the rotating trace,then the cavitation noise of propeller could be simulated using the boundary element method at arbitrary boundary conditions.Taking the propeller of 4148 as object,under the condition that the single blade cavitation volume was known,the cavitation noise of single blade was calculated based on the point source model.The calculated result agrees well with the result calculated by Ffowcs Williams-Hawkings(FW-H)equation.Then the cavitation noise of propeller was calculated.The rotation effect of propeller has a great influence on the near-field acoustic directivity of cavitation noise,but the influence on the far-field acoustic directivity can be neglected.