Aerodynamics improvement of DU97-W-300 wind turbine flat-back airfoil using slot-induced air jet

Abstract

In the present work, the effect of the passive air-blowing on the near-wake region of DU97-W-300 airfoil with blunt trailing edge is numerically investigated using ANSYS-Fluent. The airfoil was tested at a subcritical Reynolds number Re = 3.33 × 105 and deferent angles of attack, which range from 0 to 20 with an increment of 2. Three different geometrical parameters were considered in this study. These parameters are slot height, slot width, and slot inlet position. The numerical results showed that the present slot design can positively affect the aerodynamic performance of the modified airfoil. The results highlighted that the best slot geometrical design in terms of slot width and the slot inlet position was 4 mm and 0.025%c, respectively. For this design, although the lift coefficient slightly decreased, the drag coefficient significantly reduced especially at high angles of attack α > 16, thus the aerodynamic performance (lift to drag ratio) enhanced. Moreover, in the wake region, the flow domain analysis revealed that a significant reduction in turbulence kinetic energy of the slotted airfoil was achieved compared with the clean blunt trailing edge airfoil. This reduction in the turbulence kinetic energy implies that the near-wake high energy structures are mitigated. As a result, the aerodynamic noise that is directly related to the vortex shedding could be reduced. To confirm the effect of the slot, further experimental investigations on the influence of the slot design on the drag and aerodynamic noise of fixed and rotating blades are needed.

Keywords

• Blunt trailing edge airfoil
• Passive air-jet injection
• Vortex shedding control
• Wind turbine