Current knowledge on the noise generation mechanisms of an airfoil subjected to a turbulent flow indicates that an increment to the airfoil thickness leads to a reduction of the leading-edge noise. This effect is generally attributed to the turbulence distortion occurring close upstream the airfoil leading-edge, combined to a reduction in the magnitude of the aerodynamic transfer function. However, current methodologies do not allow to clearly separate the role of those two distinct physical mechanisms. This paper proposes a technique to compute the aeroacoustic transfer function allowing the study of the leading-edge noise radiated by realistic airfoil geometries. This approach is able to account for trailing-edge aerodynamic back-scattering effects and is valid for blades with large spans, general airfoil geometries, high-frequency perturbations and subsonic compressible flows. The proposed technique deals with the possibility of rewriting the linearized potential flow equations as the Helmholtz formulation leading to a boundary value problem prescribed by the linearized airfoil theory. This problem is calculated by an iterative procedure, where the linearized airfoil theory is solved by a boundary element method (BEM). The proposed numerical methodology is verified against analytical results presented by Amiet's theory. In this paper we show the importance to account for the effects of a realistic airfoil geometry in the calculation of the aeroacoustic transfer function to improve leading-edge airfoil noise prediction.
展开▼
