Distortion of anisotropic turbulence spectrum in the vicinity of aerofoil leading edge

This work numerically investigates the distortion of turbulence spectrum in the vicinity of aerofoil leading edge, which has a significant impact on the turbulence-aerofoil interaction noise. By applying different degrees of anisotropy in the incident turbulence spectrum, the effects of aerofoil thickness and angle of attack on distorted turbulence spectrum and interaction noise are investigated in the computational aeroacoustics simulations. It is shown that the turbulent eddies stretched in the streamwise direction have the slightest distortion of turbulence spectrum for symmetric aerofoils at zero incidence, compared with the isotropic case and the transversely stretched case. In addition, the increase of angle of attack has a significant impact on the anisotropic turbulence-aerofoil interaction noise, leading to the noise increase in the axially stretched case and noise reduction in the transversely stretched case. Finally, a modified far field noise prediction model is proposed by using the distorted turbulence spectrum in the vicinity of aerofoil leading edge, in order to account for the effect of real aerofoil geometries.