DESIGN AND INVESTIGATION OF THE HYDRAULIC PERFORMANCE OF BIONIC HYDROFOIL BASED ON THE GEOMETRIC FEATURES OF STURGEONS

The airfoils designed by the National Advisory Committee for Aeronautics (NACA) are currently adopted in the blades of hydraulic machinery (pump, water turbine). However, the NACA series are designed on the basis of the aerodynamics theory, so their performance are inevitably affected when they are applied directly to hydraulic machinery. Thus, the mechanism affecting the hydrodynamic characteristics of a hydrofoil based on aquatic organisms must be further investigated. In this study, a sturgeon hydrofoil based on the water environment was designed by using a 3D laser scanner, and the hydrodynamic performance of the hydrofoil was integrated by numerical simulation. A k–? SST model was adopted at Reynolds numbers 1E6, 3E6, and 5E6 under 0°–27° angle of attack for the analysis of the lift and drag coefficients, tip vortices, and pressure distribution on the upper surface of the sturgeon hydrofoil as compared with those of the NACA0012 and NACA0015 hydrofoils. Results show that the lift coefficients of the sturgeon hydrofoil are greater than those of the NACA0012 and NACA0015 hydrofoils at different Reynolds numbers. The NACA0012 and NACA0015 hydrofoils generate and spread tip vortices easier than the sturgeon hydrofoil, but the sturgeon hydrofoil generates a larger lift force before reaching the stall angle of attack, especially in the maximum-thickness region on the upper surface. Conclusions obtained in the study have important implications for designing a bionic airfoil suitable for hydraulic machinery. Keywords: Bionics hydrofoil, Fluid flow, Tip vortices, Pressure distribution, Hydrodynamic performance