Analysis of POD and EPOD for Unsteady Flow Field of Wind Turbine Airfoil

Abstract

The profile flow around the wind turbine airfoil has a significant impact on the overall performance and the noise of a wind turbine. In this paper, a combination method of large eddy simulation (LES) and the solution of Ffowcs Williams and Hawkings (FW-H) equation is used to obtain the unsteady flow field and the far-field aeroacoustic noise of a wind turbine airfoil. The dominant modes of the unsteady vorticity at the angle of attack of 8° are extracted by the proper orthogonal decomposition (POD). The modal structure of the dominant modes indicates that the trailing edge vortices and the laminar separation bubble are the main unsteady feature of the airfoil flow. The modal structures most related to the far-field aeracoustics noise are obtained by the extend proper orthogonal decomposition (EPOD). The modal results show that the vortices in the boundary layer and the large-scale vortices in the wake are most relevant to the generation and propagation of the aeracoustics noise.

Keywords

• profile flow
• large eddy simulation (les)
• aeroacoustic noise
• proper orthogonal decomposition (pod)