Experimental study on influence of sharkskin denticles structure on the hydrodynamic performance of airfoil

Abstract

The hydrodynamics properties of sharkskin have been studied for the past few decades, demonstrating the drag-reducing effect of the sharkskin surface denticle structure. This study explores the influence of the sharkskin denticles structure on the hydrodynamic performance of airfoil and the drag reduction mechanism using time-resolved particle image velocimetry (TR-PIV) by arranging the sharkskin denticles on the National Advisory Committee for Aeronautics (NACA) 0012 airfoil. The change in lift and drag of the airfoil was measured by a six-dimensional force sensor. The effects of angle of attack, sharkskin denticles location, Reynolds number, and arrangement on the hydrodynamic performance of the airfoil were mainly analyzed. The results show that for the single-row sharkskin denticles structure, the closer the bionic structure is arranged to the trailing edge of the airfoil, the better the drag reduction effect is. The maximum drag reduction is up to 25.4% by arranging the bionic denticles at 0.38L of the airfoil, when Re = 1.62 × 105 (U = 0.8 m/s) and α = 0°. For the double-row sharkskin denticles structure, the staggered arrangement is less effective in reducing drag than the aligned arrangement due to the influence of form resistance. The velocity field of the turbulent boundary layer on the airfoil surface was obtained by TR-PIV. The experiment results show that the sharkskin denticles structure can change the boundary layer of the airfoil, and the static flow area formed at the tail can reduce the disturbance of the airfoil by the turbulent flow.