Wind Tunnel Study of the Effect Zigzag Tape on Aerodynamics Performance of A Wind Turbine Airfoil

Abstract

A wind tunnel study was performed on the FFA-W-3-270 airfoil, which form a segment of a 1.25 MW wind turbine blade, to examine the effect of fixed roughness height and position using a zigzag tape boundary layer trip strip. Tests were conducted at a Reynolds number of 1×106 over a wide range of angles of attack. The zigzag tape, as an artificial roughness device, not only triggers a premature transition in the flow whereby laminar flow regimes change to turbulent, but also increases the momentum thickness of the turbulent boundary layer and change the airfoil camber. The 60o zigzag tape of 0.5 mm and 1 mm height was placed on the suction side of the airfoil at different chord wise locations. The result indicated that the thicker and the closer the tape to the leading edge had more influence on the boundary layer. Due to a drop in the flow velocity at the tape, the static pressure increased. Consequently, the tripped airfoil developed a lower pressure on the suction side in comparison to the clean airfoil. The maximum lift coefficient decreased by up to 31.5% for the 1 mm tape height located at 5% of the chord and the stall occurs at a lower angle of attack.