鸮翼前缘非光滑形态消声降噪机理

长耳鸮扑翼噪声测量试验表明,其翼前缘圆弧齿状非光滑形态对其飞行降噪影响显著。应用逆向重构技术,对长耳鸮翼前缘非光滑形态特征几何信息进行量化,并建立仿生类比模型。采用计算气动声学方法,对仿生前缘非光滑模型的降噪特性进行了数值模拟,并通过分析仿生非光滑形态对模型表面流场的影响,对仿生非光滑形态气流噪声控制机理进行了研究。结果表明,仿生非光滑模型与光滑模型相比,可降低气流噪声5～10 dB,且具备一定的增升作用;仿生前缘非光滑形态具有整流及控制气流分离的特性,可减少由于翼表面气流压力脉动及涡流脱离引发的气流噪声。

Noise reduction mechanism of non-smooth leading edge of owl wing

The winging noise of the long-eared owl was measured,and the results indicated that the circular-arc tooth shaped non-smooth leading edge of its wings has remarkable influence on its flight noise reduction.Applying the reverse reconstruction technique to quantify the geometry information about the non-smooth leading edge shape of the long-eared owl wing,a bionic analogy air foil model was built.A numerical simulation on the noise reduction characterstic of the bionic non-smooth leading edge airfoil model by computational aeroacoustics method was performed.The airflow noise control mechanism of the bionic non-smooth airfoil model was studied through the analysis of the influence of the bionic non-smoothness on the model surface flow field.It was found that comparing with the smooth airfoil model,the bionic non-smooth airfoil model can reduce the airflow noise level by 5～10 dB,and increase the lift of the airfoil.The reasoons may consist in that the non-smooth leading edge of the airfoil can rectify the flow around the airfoil and control the boundary layer strippping,reduce the airflow noise from the airflow pressure fluctuation on the airfoil surface and the turbulence breakaway.