Acoustic source distribution on aerofoils and its reconstruction from far-field array measurements
Acoustic source distribution on aerofoils and its reconstruction from far-field array measurements
复制标题
DOI：
10.1016/j.jsv.2020.115786
复制
发表时间：
2021-02
影响因子：
4.7
通讯作者：
Fabio Casagrande Hirono;P. Joseph;F. Fazi
中科院分区：
文献类型：
--
作者：
Fabio Casagrande Hirono;P. Joseph;F. Fazi
本文关注与湍流相互作用的机翼上的声源分布。源分布通常被认为等于翼型上的压力跃变，其行为可以从经典的非定常翼型理论中很好地理解。然而，该源的大部分不会辐射到远场。本文讨论应用傅立叶方法提取完美辐射到远场的机翼上的等效源分布。本文表明，虽然平板上的实际压力跃变在前缘处趋于无穷大，而在后缘处降至零（由于库塔条件），但等效源分布在翼弦上更加均匀，这解释了为什么辐射谱和单频方向性都因翼弦上相干源的干扰而表现出强烈的振荡。本文提出了一种从远场测量阵列中提取远场等效源分布的方法。
This paper is concerned with the acoustic source distribution on aerofoils interacting with a turbulent flow. The source distribution is usually taken to be equal to the pressure jump across the aerofoil, whose behaviour is well understood from classical unsteady aerofoil theory. However, much of this source does not radiate to the far-field. This paper deals with the application of Fourier methods to extract the equivalent source distribution on the aerofoil that radiates perfectly to the far-field. This paper shows that, whilst the actual pressure jump across a flat plate tends to infinity at the leading edge while dropping to zero at the trailing edge (due to the Kutta condition), the equivalent source distribution is more uniform across the aerofoil chord, which explains why the radiation spectrum and single-frequency directivity both exhibit strong oscillations due to interference from coherent sources across the chord. A method for extracting this far-field equivalent source distribution from an array of far-field measurements is proposed in this paper.