Method of bionic wavy tip on vortex and cavitation suppression of a hydrofoil in tidal energy

The tip leakage vortex (TLV) has a detrimental effect on the energy performance and operation stability of bulb turbines, which is the core component of energy conversion in tidal power stations. A hydrofoil with tip clearance is selected as the research object, the novel method of the bionic wavy tip on vortex and cavitation suppression is proposed, then the vortex structure, streamline, pressure and cavitation are analyzed numerically. The results show that the vortex structure mainly includes the tip separation vortex and TLV. A low-pressure region appears in the tip wall and suction surface (SS) and induces cavitation. The bionic wavy tip can increase the resistance of the tip leakage flow passing through the tip clearance by increasing the vertical wall shear stress at the blade tip. The large-scale TLV is divided into small-scale TLVs, which dissipate quickly. The pressure at the center of the vortex core increases, and the low-pressure region decreases. In addition, the bionic wavy tip can effectively suppress cavitation, and the cavitation volume decreases by 44%. The TLV cavitation almost disappears. However, the bionic wavy tip increases the pressure on the SS, resulting in an increase in drag and a decrease in the lift-drag ratio.