Experimental Investigation of Leading-Edge Tubercled Hydrofoils attached to a ship: Underwater Noise and Hydrodynamic Performance

Abstract

Hydrofoils installed upstream of a ship propeller offer opportunities to modify underwater noise and vessel performance, but the benefits of leading-edge tubercles in this arrangement remain unclear. This study experimentally investigates smooth and tubercled hydrofoils mounted ahead of the propeller of a KVLCC2-type model tanker. Thirty configurations, varying mounting position, wingspan, chord length and tubercle number, were evaluated over 147 runs against a bare-hull reference.

Hydrofoils installed upstream of a ship propeller offer opportunities to alter underwater noise and ship hydrodynamics, but this has rarely been proven in experiments and the underlying mechanisms remain unclear. This study experimentally investigates hydrofoils, inspired by whales’ tubercled flippers, mounted ahead of the propeller of a KVLCC2-type model tanker. Thirty configurations, varying mounting position, wingspan, chord length and tubercle number, were evaluated over 147 runs against a bare-hull reference. Underwater pressure spectra were analysed at 13 selected frequency bands, and vessel advance performance was characterised by distance per revolution (DPR). Across the tested configurations, the largest observed reduction in sound pressure spectral density level at an individual target frequency was 7.03 dB,corresponding to approximately an 80.2% reduction in pressure power spectral density at that frequency, while the highest configuration-mean DPR reached 22.03 mm/rev, representing a 7.8% increase over the bare-hull reference. These maxima represent separate acoustic and advance-performance outcomes rather than a simultaneous improvement by one configuration. Many configurations also increased spectral levels or reduced DPR, and no configuration demonstrated a consistent advantage across both performance measures and all selected frequency bands. Tubercle effects were strongly geometry-dependent: adding five tubercles to hydrofoils with a 40 mm wingspan lowered the mean spectral level by 1.85 dB at a 20 mm chord but raised it by 1.17 dB at a 40 mm chord relative to the corresponding smooth hydrofoils. These findings prove the potential benefits of this application for noise control and hydrodynamic enhancement, motivating further investigations into the physics.