Cavitation flow and noise reduction design of bionic hydrofoil based on orthogonal optimization

Abstract

Hydrofoils hold considerable academic and practical significance in the realms of marine science, energy generation, and water-based engineering. They offer enhanced speed, efficiency, stability, and maneuverability. Bionic structures have emerged as potent tools for reducing energy losses and noise in hydraulic machinery, making bionic hydrofoils a hotbed of research activity. While prominent scholars have historically directed their bionic investigations toward airfoils, operating in compressible flow fields, recent research has shifted its focus to hydrofoils. The hydrofoil's operating environment is characterized by water instead of air, featuring incompressible flow, relatively low Reynolds and Mach numbers, and notably, cavitating flow. This study presents the bionic optimization design of a wavy leading edge for the hydrofoil, employing orthogonal experimental theory. The authors establish rankings for structural parameters of bionic hydrofoils and identify optimal parameter combinations, offering an optimization strategy for selecting bionic configurations. Subsequently, the authors conduct a numerical investigation into cavitating flow, integrating the FW–H (Ffowcs Williams and Hawkings) equation for the analysis of cavitation-induced noise. Notably, this research delves into the underlying mechanisms responsible for the efficacy of bionic structures in enhancing hydrodynamic performance, particularly in the reduction of cavitation-induced noise within cavitating flow, an area scarcely explored in formal publications. The results reveal that the amplitude of the wavy leading edge exerts the most significant influence on the lift-to-drag ratio, as well as the far-field sound pressure level, followed closely by the wavelength. When compared with a baseline hydrofoil, the optimized bionic hydrofoil demonstrates a substantial 45% reduction in maximum cavity volume and a noteworthy 1.3 dB reduction in far-field noise sound pressure level. These findings underscore the capacity of the optimized bionic hydrofoil to effectively suppress cavitation and its associated noise. The established optimization strategy, focused on cavitation suppression and noise reduction, lays a robust foundation for subsequent studies involving complex working conditions.