Study of the impact of turbulent anisotropy on the airfoil turbulent boundary layer trailing edge noise

The impact of turbulence anisotropy on airfoil turbulent boundary layer trailing edge noise is investigated by a new source correlation model. The key of the new source correlation model is to utilize the Reynolds stresses for the amplitude function and different correlation length scales in streamwise and transverse directions respectively. A RANS-based noise prediction method is employed to study the impact of turbulence anisotropy on the broadband turbulent boundary layer trailing edge noise of NACA0012 airfoil. The Reynolds stresses calculated by a linear Reynolds stress model and four nonlinear anisotropic stress models are compared quantitatively with experimental data. It shows that the nonlinear Reynolds model by Gatski can achieve satisfied accuracy for Reynolds stresses in both linear and nonlinear models tested. Furthermore, the far field noise spectrum predicted by the anisotropic source correlation model based on Gatski’s Reynolds stress is in very good agreement with experiment data. In particular, the predicted spectrum by the anisotropic source model has improved significantly comparing with the results by the isotropic source correlation model at high frequency range. Further analysis also indicates that the radiated far field turbulent boundary layer trailing edge noise is mostly contributed by the streamwise Reynolds normal stress.