Aeroacoustic Simulation of a Flow around a 2-D Aerofoil (1st Report, Validation of a Large Eddy Simulation of Separated and Transitional Flow around an Aerofoil)

Abstract

A flow around a 2-D aerofoil that has a NACA 0012 cross-section is simulated by large eddy simulation with the dynamic Smagorinsky model on a high-resolution C-type mesh that consists of approximately 8 million hexahedral elements. The Reynolds number based on the chord length of the aerofoil and the uniform-flow velocity is 2.0×105 and the angle of attack is set to 9 degrees that nearly corresponds to the maximum lift condition at this Reynolds number. The results show that the boundary layer on the suction-side surface separates just downstream of the leading edge and reattaches on the surface approximately at 8% chord length downstream of the leading edge with transition to turbulence being initiated around the reattachment point. In order to investigate the accuracy of the fluctuating quantities predicted by the LES, distributions of surface pressure and wake velocity are compared with measured equivalents in terms of time-average, intensity of the fluctuations and their power spectra. The results show that the present LES is capable of predicting the separation-transition process of the boundary layer and providing accurate sound sources for the numerical prediction of aerodynamic sound.