Cavitation: Some Full Scale Experience of Complex Structures and Methods of Analysis and Observation

Abstract

The paper discusses some of the more complex cavitation structures that have been encountered in full-scale ship practice and the integration that has been observed to occur between the various substructures of the cavitating regimes. Some comparison with model scale studies is made. The paper, for the most part, concentrates on the dynamics associated with tip vortices, but also recounts, but also recounts experiences with roots and other forms of cavitation. Single, twin and triple screw situations are discussed with ship types ranging from LNG carries through container ships, cruise ships, high-speed patrol craft and small warships. The analysis of hull surface pressure signals originating from cavitation action is also discussed in relation to cavity phenomenological behavior. With regard to observation methods, the currently available and practical techniques are discussed; semicolon comparing and contrasting the techniques and their relevance to problem-solving based on Lloyd’s Register’s full-scale experience. Additionally, a new borescope method, pioneered and developed by Lloyd’s Register, which has successfully been used in a number of full-scale investigations is also presented.