Computation of surface acoustic characteristics of NACA0012 airfoil with smooth rime ice on the leading edge

Ice accretion can change the shape of airplane aerodynamic surface. Not only it can result in the degradation of aerodynamic performance, but also it can lead to the variation of aeroacoustic characteristics. In order to explore the effect of ice accretion on the aerodynamic noise, the surface acoustic characteristics of NACA0012 airfoil with smooth rime ice on the leading edge is studied numerically by the computational fluid dynamics method (CFD). C-type topology grids are generated to distribute the computational domain of iced airfoil. The incompressible Reynolds-averaged Navier-Stokes equations are used to simulate the viscous flow field around the iced airfoil. The broadband noise model based on Proudman theory and the Curle surface integral method are adopted to predict the surface acoustic parameters of the iced airfoil. The surface acoustic power and surface acoustic power level distribution along iced airfoil chordwise are obtained emphatically. It is shown that the flow transition or flow separation near the rime ice model on the leading edge results in high surface acoustic power of iced airfoil at zero or small angle of attack. Flow separation or flow transition appears in the region near the trailing edge, which can increase the surface acoustic power along the trailing edge at high angle of attack, further increasing surface acoustic power of the iced airfoil. The flow transition and flow separation on iced airfoil caused by the rime ice on the leading edge are the main reason for increasing aerodynamic noise.