Effect of Wavy Leading Edge with Various Aspect Ratios on a Rectangular Wing

Learning from nature, the humpback whale can swim faster than other baleen whales. The humpback whale has the flipper with wavy leading edges (WLE), which has an improvement of hydrodynamic performance. The WLEs have the function to generate vortices to maintain lift and to prevent stall at high angles of attack. This research aim is to find out the WLE effect on hydrodynamic performance in different wing aspect ratios (AR), whose profile is the rectangular wing of NACA 0018 as a baseline wing. The WLE profile was designed by a sinusoidal function. We focused on steady flow conditions in both the experiments and numerical simulations. The experimental work was conducted in the circular water channel at Hiroshima University, Japan. Meanwhile, the numerical work was employed using RANS simulation with SST k-ω turbulence model. Based on the results, we clarified that the increase of AR could possess a higher lift coefficient (Cl), and then physically interpreted the WLE effect on various aspect ratios. This knowledge could be expanded into the application of eco-friendly energy-saving devices such as fin stabilizers of ships and wind turbines to improve hydrodynamic performance.