STG Symposium "Selected Topics on Strength, Vibrations and Noise"

Experimental Parameters Influencing the Cavitation Noise of an Oscillating NACA0015 Hydrofoil

Leonie Föhring, Fachhochschule Kiel

The strong increase of anthropogenic underwater noise along the worldwide shipping routes has caused a growing intention to design quieter ships. A cavitating, oscillating 2D NACA0015 hydrofoil is analysed in a cavitation tunnel as a simplified and manipulatable representative of a propeller blade in a ship’s wake field for the identification of major influencing parameters on the radiated noise. Three different asymmetrical courses of the angle of attack are tested with various cavitation numbers. The combination of a moderate angle increase and a rapid decrease is found to generate significantly higher pressure peaks compared to symmetrical angular courses. Considering that the rapid change of the angle of attack caused by the inhomogeneous wake field behind the hull is the core of the cavitation occurrence, the understanding of its influence may contribute to the design of quieter ships in the future while still allowing for the necessary high propeller efficiency.