Research on aerodynamic performance of a novel dolphin head-shaped bionic airfoil

Highlights: • Head shape of fastest swimming Phocoenoides dalli is the bionic object for airfoil. • Dolphin head-shaped airfoils are produced based on bionics and hydrodynamics. • Aerodynamic analysis of dolphin head-shaped airfoils are carried out numerically. • Dolphin head-shaped airfoils with various deflection angles are analyzed. Based on the special streamline profile of the Phocoenoides dalli head, this paper innovatively proposes to transform the NACA 0018 airfoil into a novel airfoil whose leading edge is similar to the streamline profile of the Phocoenoides dalli head, and makes corresponding minor adjustments to this new airfoil according to the dolphin's motion behavior, and eventually obtains three kinds of dolphin head-shaped new airfoils including the Original Dolphin Airfoil, the Smooth Transition Dolphin Airfoil and the Deflected Dolphin Airfoil. Due to different deflection angles, the Deflected Dolphin Airfoil is then subdivided into five different types. The aerodynamic performances of these three dolphin head-shaped new airfoils as well as the NACA 0018 airfoil are simulated by using the SST k-ω model at Re = 1.6 × 10⁵. The results show that: Compared with the NACA 0018 airfoil, firstly, the aerodynamic performances of three kinds of dolphin head-shaped airfoils are quite different from each other because of the change of the curvature and the radius of the leading edge. Secondly, by comparing the lift and drag coefficients of the Deflected Dolphin Airfoils with five deflection angles, it is speculated that there is an optimal deflection angle for the Deflected Dolphin Airfoil under the conditions of this paper. Eventually, the deflection angle of 24° is found to be the optimal value among these five different deflection angles. The results of this study can provide reference for improving the performance of blade design, such as the rotating mechanical blades, the aeronautical blades, etc.