Experimental research on cavitating hydrodynamic characteristics of NACA0015 hydrofoil and its biomimetic counterpart

Abstract

The biomimetic hydrofoils are frequently employed to enhance cavitation performance, although the underlying mechanisms remain to be fully elucidated. This study utilizes a cavitation visualization experimental system and mechanical characterization to experimentally investigate the transient cavitation features of a NACA0015 hydrofoil and its biomimetic counterparts with modified lending-edge. The findings demonstrate that, in comparison with the flat hydrofoil, the biomimetic hydrofoil experiences a cavitation morphology transition at a lower cavitation number, with a reduction of up to 0.38. Moreover, the maximum cavity length and the maximum cavitation area are reduced by 17.11%, 17.32%, signifying a reduction in cavitation intensity. Proper orthogonal decomposition (POD) analysis revealed that the primary mechanism for the enhanced cavitation performance of the leading-edge wave structured biomimetic hydrofoil is the suppression of cloud cavitation shedding. At an attack angle of 6°, the biomimetic hydrofoil exhibited the highest lift coefficient increase of 18.56%, corresponding to a lift-to-drag ratio improvement of 9.56%. By analyzing the cavitation patterns of the two hydrofoils, it is evident that the rate of change in the maximum cavity length isolines for the biomimetic hydrofoil is lower than that of the flat hydrofoil. For an equivalent level of cavitation intensity, the biomimetic hydrofoil exhibits a lower cavitation number compared with the flat hydrofoil. These demonstrate that the wavy leading-edge design of the biomimetic hydrofoil effectively reduces the severity of cavitation, thereby confirming the efficacy of the biomimetic hydrofoil in enhancing cavitation performance.