Numerical analysis of noise reduction mechanisms of serrated trailing edges under zero lift condition
Numerical analysis of noise reduction mechanisms of serrated trailing edges under zero lift condition
复制标题
零升力条件下锯齿状后缘降噪机理数值分析
DOI：
10.2514/6.2017-4173
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
D. Ragni
中科院分区：
文献类型：
--
作者：
W. V. D. Velden;F. Avallone;D. Ragni
研究了锯齿形和梳齿形尾缘存在时的远场噪声与流场的关系，解释了相关的降噪机理。这两种锯齿几何结构都改装成了NACA 0018机翼。计算是通过求解完全显式的、瞬变的、可压缩的格子Boltzmann方程进行的，而声学远场是通过Ffowcs-Williams和Hawking积分解得到的。提出了远场噪声与产生噪声的相关流动参数之间的联系。结果表明，表面压力脉动的强度沿流向变化，大部分低频噪声产生在锯齿的根部。结果表明，使用梳子的额外降噪效果是由于减少了根部的外流运动。此外，表面压力波动沿边缘方向的关联长度和对流速度是影响降噪强度和频率范围的两个统计流动参数。研究发现，较大的沿边缘方向的相关长度通过在沿倾斜边缘散射的压力波之间产生相消干涉而有助于降低噪声。
The relation between the far-field noise and the flow field, in presence of serrated and combed-serrated trailing edge, is studied to explain the associated noise reduction mechanisms. Both serration geometries are retrofitted to a NACA 0018 wing. Computations are carried out by solving the fully explicit, transient, compressible Lattice Boltzmann equation , while the acoustic far-field is obtained by means of the Ffowcs-Williams and Hawking integral solution. A link between the far-field noise and the relevant flow parameters that contribute to noise generation is proposed. It is confirmed that the intensity of the surface pressure fluctuations varies in the streamwise direction, and that most of the low-frequency noise is generated at the root of the serrations. It is concluded that the additional noise reduction achieved by the use of combs is due to the mitigation of the outward flow motion at the root. Furthermore, it is shown that the edge-oriented correlation length and the convection velocity of the surface pressure fluctuations are the two statistical flow parameters that influence both the intensity and the frequency range of noise reduction. It is found that a larger edge-oriented correlation length contributes to noise reduction, by generating destructive interference between the pressure waves scattered along the slanted edge.
影响因子：
3.7
作者：
L. E. Jones;R. Sandberg
通讯作者：
L. E. Jones;R. Sandberg