Visualization of the flow field and aerodynamic force on a Horizontal Axis Wind Turbine in turbulent inflows

The evaluation of the stall phenomenon around an airfoil of the Horizontal Axis Wind Turbine (HAWT) was investigated experimentally in turbulent inflows. In order to observe the aerodynamic characteristics, pressures acting on a single rotor surface were measured by a multiport scanner. Furthermore, in order to present flow visualization, blade surface tufts and oil film methods were used to gain insight on the flow characteristics of HAWT airfoil. In this experiment, aerodynamic forces and flow visualization were discussed with different turbulence intensities and low Reynolds numbers. As a result, it is clarified that the flow is separated at the blade leading edge. For the case of TI = 0.20% and Re = 2.0 × 105, the flow is reattached at the trailing edge when the angle of attack is 7°. For the cases of TI = 5.0% and 13.9%, flow separation is generated near the trailing edge. For the flow visualization of oil film method, separation bubble is observed at the case of TI = 0.20% and Re = 2.0 × 105. However, separation bubble is not found at the high turbulence intensities of TI = 5.0% and 13.9%. These results are also similar to investigations at the result of pressure distribution.