Study of cavitation and noise characteristics of hydrofoil with bionic groove–nodule leading edge structure

Cavitation in fluid machinery degrades hydrodynamic performance and generates severe vibration and noise. Inspired by humpback whale pectoral flipper tubercles, this study proposes a bionic groove–nodule leading-edge structure for the NACA0009 hydrofoil to synergistically suppress cavitation and radiated noise. A steady-state RANS simulation based on the Shear Stress Transport k–ω model provides the initial flow field, followed by large eddy simulation (LES) coupled with the Schnerr–Sauer cavitation model to resolve the unsteady cavitating flow. All results are derived from the transient LES data at an angle of attack of 10° and cavitation number σ = 1.07, corresponding to the optimal design point from a preliminary parametric screening. The bionic structure modifies the pressure distribution and delays suction-surface flow separation, achieving up to 66% reduction in vapor volume. The groove–nodule leading edge disrupts sheet cavitation into complex three-dimensional vortex systems, fragmenting large-scale vortical structures into smaller dissipative clusters. This reduces surface dipole source strength and, as inferred from coherence analysis, relatively increases quadrupole source contributions with lower radiation efficiency. Within the 300–600 Hz critical band, the bionic hydrofoil achieves an average far-field sound pressure level (SPL) reduction of 10.2 dB, with a peak overall SPL decrease in 7.07 dB. Coherence analysis confirms a 21.6% reduction in flow–acoustic coupling strength across the entire frequency band. This study demonstrates the dual efficacy of the bionic design in simultaneously suppressing cavitation and broadband noise, offering biomimetic insights for high-performance, low-noise hydraulic blades.