Design approach and hydrodynamic characteristics of a novel bionic airfoil

Airfoil is the basic structure in the field of fluid machinery and is widely used in aerospace, petrochemical, and hydraulic machinery. In this study, three nonbionic airfoils (S-down, S-level, and S-up) in the side direction of sturgeon and three bionic airfoils (S-top1, S-top2, and S-top3) in the top direction of sturgeon were established via the B-spline curve-fitting technique. Different schemes were simulated by applying large eddy simulation. The simulation results are consistent with the experimental results. The lift coefficient of an asymmetric bionic airfoil is significantly greater than that of a symmetric airfoil, with S-down scheme having the largest lift coefficient. The vortex region is related to velocity fluctuation and Reynolds stress distribution. When the vortex region is close to the tail edge, it has a minimal effect on the mainstream. The leading edge of the asymmetric bionic airfoil is prone to vortices, and the vortex area is associated with the upwarping angle of the leading edge. The leading edge of the symmetric bionic airfoil tends to form a stable vortex structure; as the stable vortex area expands, the lift coefficient increases correspondingly. These findings can provide theoretical support for the design of hydraulic blades.