Computation of quadrupole noise using acoustic analogy
Computation of quadrupole noise using acoustic analogy
复制标题
使用声学类比计算四极噪声
作者：
Meng Wang;S. Lele;P. Moin
在二维低马赫数层流背景下，对弦雷诺数为104的NACA 0012翼型进行了旋涡脱落噪声的声学模拟计算。数值求解了不可压缩的N-S方程，给出了近场流动动力学和声源函数的近似描述。基于Curle对Lighthill类比的推广，计算了辐射远场噪声。这项研究强调在大范围尾迹存在的情况下对雷诺应力四极杆的准确评估。提出了一种有效的分离物理噪声源和通过可渗透计算边界的涡流引起的伪边界贡献的方法。文中还研究了震源区域内延迟时间变化的影响。计算结果表明，当自由流马赫数较小时，四极子噪声比升力和阻力偶极子噪声弱。这项研究中开发的技术同样适用于体积四极子作为显著噪声源的流动。
Acoustic analogy computations of vortex shedding noise were carried out in the context of a two-dimensional, low-Mach-number laminar flow past a NACA 0012 airfoil at chord Reynolds number of 10 4 . The incompressible Navier-Stokes equations were solved numerically to give an approximate description of the near-field flow dynamics and the acoustic source functions. The radiated far-field noise was computed based on Curle's extension to the Lighthill analogy. This study emphasizes an accurate evaluation of the Reynolds stress quadrupoles in the presence of an extensive wake. An effective method for separating the physical noise source from spurious boundary contributions caused by eddies crossing a permeable computational boundary is presented. The effect of retarded-time variations across the source region is also examined. Computational solutions confirm that the quadrupole noise is weak compared with the noise due to lift and drag dipoles when the freestream Mach number is small. The techniques developed in this study are equally applicable to flows in which the volume quadrupoles act as a prominent noise source.