Numerical and experimental investigation of the flow separation over NREL's S822 aerofoil and its control by suction and blowing

摘要

In this study, a numerical and experimental investigation for the flow separation over 170 mm chord, the NREL S822 aerofoil low Reynolds number wind turbine blade aerofoil section has been investigated at 15.8 m/s wind speed using suction and blowing techniques for the locations between 0.15 and 0.41 of the chord to improve aerodynamic characteristics of a wind turbine rotor blade. In a numerical study, two-dimensional aerofoil (i.e. NREL S822), using Shear Stress Transport (SST (- Re_)) turbulence model, is presented. Careful selection for the number of mesh was considered through an iterative process to achieve the optimum mesh number resulted in optimum values for the ratio of lift to drag coefficients (C_L/C_D). Values of the lift coefficient, drag coefficient, and separation location were investigated at an angle of attack 18. Flow separation is monitored and predicted within the numerical results at the tested angles, which has been compared with the experimental results and should a fair agreement. The results revealed that the aerodynamic characteristics of NERL S822 aerofoil would be improved using the suction technique more than the suction and blowing techniques and there is a delay of flow separation with the increase of blowing or suction volumetric flow rate. Using these two techniques and careful selection of the mesh numbers with the right angle of attack can improve the aerofoil characteristics and therefore lead to improve the turbine performance characteristics.