Experimental Investigation of Airfoil Turbulence-Impingement Noise Reduction Using Porous Treatment
Experimental Investigation of Airfoil Turbulence-Impingement Noise Reduction Using Porous Treatment
复制标题
多孔处理降低翼型湍流冲击噪声的实验研究
DOI：
--
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
C. Schram
中科院分区：
文献类型：
--
作者：
R. Zamponi;D. Ragni;N. Wyer;C. Schram
目前的工作旨在评估使用多孔材料降低翼型湍流冲击噪声的有效性。为了实现这一目标，我们设计了填充三聚氰胺泡沫的多孔 NACA-0024 型材，以便与实体模型进行比较。构成翼型的多孔介质已得到充分表征，以确定描述材料的参数。这两种型材已在冯卡门流体动力学研究所的消声室中在杆翼型配置中进行了测试。测试中考虑了 30 m/s 的自由流速度（对应于基于弦的雷诺数 3.2·105）和 0° 的迎角。进行了热线风速测量，目的是表征两个翼型周围的边界层，并研究由于多孔处理而发生的最终鼻部缓解机制。此外，还研究了沿两个表面的静压分布，以找出与速度分布的相关性。结果表明，多孔处理的使用导致低频范围内的湍流冲击噪声减少，而高频范围内的湍流冲击噪声增加，这主要是由于表面粗糙度噪声造成的。逆波束形成技术的应用可以对两种情况下不同三分之一倍频程频率下的噪声分布图进行定性比较。此外，对前缘周围矩形区域内每个地图点的压力值进行了求和，以便检索积分的三分之一倍频程频谱。
The present work aims at evaluating the effectiveness of the use of porous materials for reducing airfoil turbulence-impingement noise. To pursue this objective, a porous NACA-0024 profile filled with melamine foam has been designed for comparison with a solid model. The porous media constituting the airfoil has been fully characterized in order to determine the parameters that describe the material. The two profiles have been tested in a rod airfoil configuration in the anechoic chamber of von Karman Institute for Fluid Dynamics. A free-stream velocity of 30 m/s (corresponding to a chord-based Reynolds number of 3.2·105) and an angle of attack of 0◦ have been considered for the tests. Hot-wire anemometry measurements have been performed with the aim of characterizing the boundary layers around the two airfoils and investigating the eventual nose mitigation mechanisms that occur due to the porous treatment. Moreover, the static pressure distributions along the two surfaces have been studied to find correlations with the velocity profiles. The results show that the use of a porous treatment leads to a decrease of turbulence-impingement noise in the low-frequency range and to an increase in the high-frequency one, mostly due to surface roughness noise. The application of an inverse beamforming technique has lead to a qualitative comparison of noise distribution maps at different one-third octave band frequencies for the two cases. Furthermore, the pressure values of each map point within a rectangular region surrounding the leading edge have been summed in order to retrieve the integrated one-third octave band spectra.