S. Huang - School of Energy and Power Engineering, University of Shanghai for Science and Technology ۲, Shanghai, ۲۰۰۰۹۳, China
H. Qiu - Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong
Y. Wang - School of Energy and Power Engineering, University of Shanghai for Science and Technology ۲, Shanghai, ۲۰۰۰۹۳, China

To further improve the lift-rising effect of the attached flap on an airfoil, based on the unique movement pattern of a fluke when a dolphin moves forward, this paper puts forward a novel attached split flap model with variable curvature. The lift-type vertical axis wind turbine's typical blade airfoil NACA ۰۰۱۸ is taken as the research object. First, the aerodynamic performance of the two-dimensional airfoil is simulated based on the SST k-ω turbulence model. The contrast between the simulation and the experimental results proves the correctness of the numerical simulation methods in this paper. Then, the effectiveness of split flap is verified, and the lift-rising principle is briefly analyzed. Finally, the parametric study is carried out based on the flap model with variable curvature proposed in this paper, and the lift-rising principle of the variable curvature split flap is analyzed in detail. The results indicate that, with the rise of the flap's curvature index, the airfoil's lift coefficient (Cl) integrated with the flap gradually increases accordingly and tends to a constant value. The bionic research in this paper can provide a comprehensive reference for the aerodynamic shape design of airfoil trailing edge flap and the further optimization of energy efficiency of rotating machinery or aviation.

Split flap, Variable curvature, Vertical axis wind turbine, Flow control, Parameter optimization