Sound signature of propeller tip vortex cavitation. (November 2015)

• Record Type: Journal Article
• Authors: Pennings, Pepijn; Westerweel, Jerry; van Terwisga, Tom
• Is Part Of: Journal of physics. Number 656(2015)
• Publication Date: 2015-11
• Subjects: Physics -- Congresses; 530.5
• DOI: 10.1088/1742-6596/656/1/012186
• Languages: English
• ISSNs: 1742-6588

Abstract

Abstract: The design of an efficient propeller is limited by the harmful effects of cavitation. The insufficient understanding of the role of vortex cavitation in noise and vibration reduces the maximum efficiency by a necessary safety margin. The aim in the present study is to directly relate propeller cavitation sound to tip vortex cavity dynamics. This is achieved by a dedicated experiment in a cavitation tunnel on a specially designed two-bladed propeller using a high-speed video camera and a hydrophone. The sound signature of a tip vortex cavity is not evidently present in the sound spectrum above the tunnel background. The addition of a simulated wake inflow results in a high amplitude broadband sound. With a decrease in the free-stream pressure the centre frequency of this sound decreases as a result of a larger vortex cavity diameter. In the near future each blade passage in the high-speed video will be analyzed in detail. The frequency content of the cavity dynamics can then be directly related to the measured sound. An analytic model for vortex cavity dynamics resulting in a cavity eigenfrequency using a vortex velocity model can finally be evaluated as a design instrument for estimation of broadband sound from propeller cavitation.