逆压区域锯齿结构翼型气动噪声特性研究

Aerodynamic noise characteristics of serrated structure airfoil in adverse pressure gradient

为了研究翼型在逆压梯度区域内的流动控制和气动噪声特性,在NACA0018翼型0.45~0.50倍弦长区域内设置三种锯齿结构,应用Lighthill声类比方法对比分析了翼型在不同工况下的近场和远场气动噪声特性。结果表明,逆压梯度区域内锯齿翼型的近壁面湍流强度随锯齿夹角的增大而增大,锯齿翼型流动分离点的位置比干净翼型提前,90°锯齿翼型的动压幅值降低;翼型的主要噪声源分布在翼型吸力面沿至尾流区域,90°锯齿夹角翼型在翼型弦长中点上方和前方0.5 m处的噪声分别降低了约1 dB和3 dB;增大来流速度使翼型近场的最大总声压级方向由0°变为10°;90°锯齿翼型在不同来流速度下近场和远场的降噪效果良好。

In order to study the flow control and aerodynamic noise characteristics of airfoil within its adverse pressure gradient range,three serrated structures were set in the 0.45~0.50 times chord length region of the NACA0018 airfoil,and the near-far-field aerodynamic noise characteristics of the airfoil under different working conditions were analyzed by the Lighthill acoustic analogy method.The results show that,with the increase of the serrated angles,the turbulence intensity of the near-wall surface in the adverse pressure gradient increases continuously.The position of the flow separation point of the serrated airfoil is earlier than that of the clean airfoil,which reduces the dynamic pressure amplitude of the 90°serrated airfoil.The main noise sources of the airfoil are distributed from the suction surface of the airfoil to the wake region.The noise of the 90°serrated angle airfoil is reduced by about 1 dB above the midpoint of the airfoil chord and 3 dB at 0.5 m in front of the airfoil.The increase of the incoming flow changes the direction of the maximum total sound pressure level in the near field of the airfoil from 0°to 10°.The 90°serrated airfoil can play a good noise reduction effect in the near field and far field at different flow speeds.