带脊状结构风力机翼型的噪声特性研究

采用大涡模拟和声类比的方法,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约为8.0×10⁴和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翼型的流场和声场。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,同时能提高翼型的气动性能。逆压梯度段脊状结构可有效减小频率在0~3000 Hz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主导。

AERODYNAMIC AND NOISE CHARACTERISTICS OF AIRFOIL WITH RIDGED STRUCTURE

Using large eddy simulation and acoustic analogy method,the NACA0018 airfoil was taken as the research object to study the influence of ridge structure on airfoil far-field noise. To simulate the airfoil flow field with ridge structures,choosing the flow speed of12 and 24 m/s respectively and the attack angle of 6°,and the corresponding Reynolds number based on chord length was approximately8.0×10⁴ and 1.6×10⁵. The FW-H equation was used to calculate the sound source term extracted by the large eddy simulation,so the flow field and acoustic field of Riblet-Q and Riblet-H airfoil were acquired. The calculation results of unsteady flow field show that:under the attack angle of 6°,Riblet-H airfoil can improve the boundary layer separation of airfoil and suppress the shedding of vortex structures,thus reducing the pressure fluctuation of the airfoil surface and the sound pressure fluctuation at the receiving point,and improving the aerodynamic performance of the airfoil at the same time. 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 dominated the vortex shedding noise caused by the boundary layer.