Influence of boundary layer flow suction on trailing edge noise generation
Influence of boundary layer flow suction on trailing edge noise generation
复制标题
边界层流吸力对后缘噪声产生的影响
DOI：
10.1016/j.jsv.2020.115276
复制
发表时间：
2020
影响因子：
4.7
通讯作者：
M. Azarpeyvand
中科院分区：
文献类型：
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作者：
Máté Szőke;D. Fiscaletti;M. Azarpeyvand
本文从气动声学的角度研究了均匀斜流抽吸对平板上发展的平衡湍流边界层的影响。同时测量流向速度与热线风速仪，表面压力波动，使用齐平安装的麦克风进行了在不同位置的流量控制处理下游。本文讨论了流动抽吸对描述边界层的湍流量的影响，以及相关的流体动力压力场，以评估流动抽吸对后缘噪声产生的影响。改变两个参数，即流动抽吸速度（α）和流动抽吸强度（σ）的倾斜度。前者是相对于自由流的流动抽吸角（α= 30°、50°、70°和90°），后者是边界层内的动量亏损与流动抽吸动量的比值（σ= 2.5-9.1）。流动抽吸降低了边界层的高度，这导致平均剪切的增加。在边界层内的流动能量含量减少的吸力与最显着的减少量是在对数区域内观察。在缓冲层中观察到适度的能量增加。这些影响随着吸力强度的增加而加强，直到σ ≥ 6。在这一点以上，观察到湍流量没有进一步的变化。对数层的尺寸和能量含量的减少是负责在中频的表面压力波动的减少，而在缓冲层中的能量含量的增加增加在高频的压力谱内容。远场后缘噪声的估计表明，流抽吸导致在中频处的噪声降低，在低频和高频处观察到惩罚。在α= 70°和σ = 6的角度下的气流抽吸在降低估计的远场总体噪声水平方面表现出最佳性能。在该点以上，进一步增加流动抽吸强度不会提供任何额外的降噪益处。
The effect of uniform inclined flow suction on an equilibrium turbulent boundary layer developing over a flat plate is experimentally investigated for aeroacoustic purposes. Simultaneous measurements of streamwise velocity with hot-wire anemometry, and surface pressure fluctuations using flush-mounted microphones were performed at various locations downstream of the flow control treatment. The paper discusses the effects of flow suction on the turbulent quantities describing the boundary layer, and the associated hydrodynamic pressure field to assess the effects of flow suction on trailing edge noise generation. Two parameters were varied, the inclination of the flow suction velocity (α) and the flow suction severity (σ). The former is the angle of flow suction with respect to the free-stream flow (α= 30°, 50°, 70° and 90°), while the latter is the ratio of momentum deficit within the boundary layer to the momentum of flow suction (σ= 2.5–9.1). Flow suction reduces the height of the boundary layer, which results in an increase of mean shear. The flow energy content within the boundary layer is reduced by suction with the most significant amount of reduction is observed within the logarithmic region. A moderate energy increase is observed in the buffer layer. These effects strengthen with growing suction severity untilσ≈ 6. Above this point, no further changes are observed in the turbulent quantities. The reduction in the size and energy content of the logarithmic layer is responsible for the reduction of the surface pressure fluctuations at mid-frequencies, while the increased energy content in the buffer layer increases the pressure spectral content at high frequencies. The estimates of the far-field trailing edge noise show that flow suction leads to a noise reduction at mid-frequencies with penalties observed at low and high frequencies. Flow suction at an angle ofα= 70° andσ≈ 6 exhibits the best performance in reducing the estimated far-field overall noise levels. Above this point, further increasing the flow suction severity does not provide any additional noise reduction benefits.