Computational Aerodynamic Analysis Of Flatback Airfoils By Coupling N-S Equations And Transition Prediction Codes
Free (open access)
45 - 54
L. Deng, Y. W. Gao & J. T. Xiong
Flatback (Blunt Trailing Edge) airfoils are adopted for the inboard region of large wind turbine blade due to their structural and aerodynamic performance advantages. Very limited experimental data at high Reynolds Number makes it difficult for wind turbine designers to design and use these section shapes because the wind tunnel experiments are limited by the Reynolds Number and the solid blockage. In this study, a 2-D Reynolds-Average Navier- Stokes Solver coupled with a transition prediction based on the eN method is used to CFD computation of blunt trailing edge airfoils. A new coupling structure with a timeaccurate transition prediction model taking the unsteady flow as a result of the bluff-body vortex shedding into account is developed. The computational grid is C-Grid generated by the tool of Gridgen, and the vertical angle at the blunt trailing edge is smoothed slightly to increase the grid quality. An airfoil of DU97-Flat modified by DU97-W-300 airfoil for wind turbine application is calculated and effects of grid points are investigated. The aerodynamic performance of DU97-W-300 is calculated and comparisons between the results from literature and wind tunnel experimental data are performed, and the results show that the method in present study can obtain the aerodynamics performance with much less grid numbers while agreeing better with the wind tunnel experimental data than the literature. One issue that requires attention is the prediction of maximum lift and the failure to accurately capture stall behaviour by the various computational techniques used in this study. Keywords: wind turbine, airfoil, flatback airfoil, couple, transition prediction.
wind turbine, airfoil, flatback airfoil, couple, transition prediction