Spurious wave contaminations may occur in the computations of acoustic far-field directivities in turbulent flows with only surface integrations. Two methods could be used to tackle the problem: (1) to take average of the solutions using multiple integration surfaces based on the Ffowcs-Williams and Hawkings equation that was widely applied to various aeroacoustics problems, and (2) to use the generalized sound extrapolation method based on an indirect acoustic variable to filter out the non-acoustic fluctuations in turbulent flows. The performances of the two methods are investigated by applying to the representative broadband airfoil leading edge noise and turbulent jet noise problems. For the Ffowcs-Williams and Hawkings approach, the prediction accuracy is sensitively influenced by the number and location of the integration surfaces. It often requires more than 10 well-configured surfaces to yield a convergent solution compare to the indirect acoustic variable method. The properties of robust and low computation cost of the indirect acoustic variable method suggest that it is potentially useful for the far-field computations of the aeroacoustics problems.

中文翻译：

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湍流声学远场预测方法的比较

在仅使用表面积分的湍流中的声学远场方向性计算中可能会出现杂散波污染。可以使用两种方法来解决这个问题：(1) 使用基于广泛应用于各种气动声学问题的 Ffowcs-Williams 和 Hawkings 方程的多个积分面对解求平均值，以及 (2) 使用广义声音基于间接声学变量的外推法滤除湍流中的非声学波动。通过应用于具有代表性的宽带翼型前缘噪声和湍流喷射噪声问题来研究这两种方法的性能。对于 Ffowcs-Williams 和 Hawkings 方法，预测精度受积分面的数量和位置的敏感影响。与间接声学变量方法相比，它通常需要 10 个以上配置良好的表面才能产生收敛解。间接声学变量方法稳健且计算成本低的特性表明它对于气动声学问题的远场计算具有潜在的有用性。