Numerical Simulation of Surface Roughness Effect on Wind Turbine Thick Airfoils

The full two-dimensional Navier-Stokes algorithm and the k-omega SST turbulence model were used to investigate incompressible viscous flow past the wind turbine two-dimensional airfoils under clean and roughness surface conditions. The NACA 63-430 airfoil is chosen to be the subject, which is widely used in wind turbine airfoil and generally located at mid-span of the blade with thickness to chord length ratio of about 0.3. The numerical simulation of the airfoil under clean surface condition was done. As a result, the numerical results had a good consistency with the experimental data. The wind turbine blade surface dust accumulation according to the operation periods in natural environment was taken into consideration. Then, the lift coefficients and the drag coefficients of NACA 63-430 airfoil were computed under different roughness heights. The role that roughness plays in promoting premature transition to turbulence and flow separation has been verified by the numerical results. The trend of the lift coefficients and the drag coefficients with the roughness increasing was obtained, and the critical value of roughness height was proposed. Furthermore, the effect of the different roughness locations on the performance of NACA 63-430 airfoil was studied, and the critical value of roughness location was proposed.