带脊状结构的NACA0018翼型气动噪声特性

为了减少翼型的气动噪声，采用声类比的方法，以NACA0018翼型为研究对象，研究脊状结构对翼型远场噪声的影响。分别模拟来流速度为12 m/s和24 m/s，在6°攻角下布置脊状结构的翼型流场，对应的基于弦长雷诺数大约为1.6×105。通过FW-H方程计算大涡模拟提取的声源项，得到Riblet-Q和Riblet-H翼型的声场。非定常流场计算结果表明：6°攻角下Riblet-H翼型能够改善翼型边界层分离情况，抑制涡结构脱落，从而减小翼型表面压力脉动和接收点处声压波动。逆压梯度段脊状结构可以有效减小频率在0-3000Hz内的噪声。进一步研究表明，该状态下的噪声主要由边界层引起的涡脱落噪声所主导。可见，适当位置的脊状结构可以改善翼型的噪声情况。

Noise Characteristics of Airfoil With Ridged Structure

In order to reduce the aerodynamic noise of the airfoil, acoustic analogy was used. the research object was the NACA0018 airfoil, and the effect of ridge structure on the far-field noise of airfoil was analyzed. To simulate the airfoil flow field with ridge structures, choosing the flow speed of 12 m/s and 24 m/s respectively and the attack angle 6°, and the corresponding Reynolds number based on chord length was about 1.6×105. The sound source extracted by large eddy simulation was calculated through the, so the acoustic field of Riblet-Q and Riblet-H airfoil were acquired. The calculation results of unsteady flow field show that: under the attack angle 6°, Riblet-H airfoil can improve the boundary layer separation of airfoil and suppress the shedding of vortex structures, so as to reduce the pressure pulsation on the airfoil surface and the sound pressure fluctuation at the receiving point. The ridge structures of adverse pressure gradient section can effectively reduce noise when the frequency within 0-3000 Hz. Further research shows that the noise in this state is mainly the vortex shedding noise caused by boundary layer. It is concluded that the ridge structure in the proper position can improve the noise condition of the airfoil.