Numerical and experimental studies of hydrodynamic performance of bionic leading-edge tubercle airfoil

This paper studies the bionic tubercle airfoils based on the NACA 0020 prototype airfoil, with 7 models derived from different designs of the span-chord ratios and different tubercle types, along with the option of the wave airfoil surface matching the leading-edge tubercle. Open water experiments are conducted to test the airfoil profile at a Reynolds number of 3×105 and an angle of attack of 0°–30°. Data are recorded by a four-component force balance and the resulted lift, drag, and force moment are analyzed. From the analysis of the hydrodynamic characteristics and the flow field characteristics, it is shown that the stall of the tubercle airfoils is milder without an evident stalling angle as compared with that of the normal airfoil profile. The lift coefficient of the optimized airfoil is significantly elevated at the angle where the NACA 0020 airfoil is in the stall condition. The lift-drag ratio is also markedly improved at the same angle. The optimal airfoil profile is finally identified and a further optimization plan is proposed based on the comparison results against the CFD numerical simulation.