Primary study on return flow of the central wake area of horizontal axis wind turbine

Through applying PIV(Particle Image Velocimetry) test on center wake of the horizontal-axis wind turbine in low-speed blow down wind tunnel and reveal the regularities of distribution of air flow passing the blades at relative velocity under the design wind speed. At the same wind speed, with the increase of tip-speed ratio λ the influence region of backflow decreases; Meanwhile at the same tip-speed ratio λ, with the increase of wind speed the influence region of backflow decreases; In a certain range, with the increase of X/R axial velocity decrease, with the increase of Y/R radial velocity increase; The backflow and the air flow passing the blades collect in certain areas and form a clear dividing boundary.