Cavitation volume behaviour derived from full-scale pressure fluctuations

ABSTRACT

This study uses measurements of pressure fluctuations of a full-scale ship for the calculation of the cavitation volume based on an acoustical model. The sound pressure signal had been recorded by pressure sensors mounted above the propeller of a 3600 TEU container vessel, combined with a synchronous tachometer signal from the propeller shaft. An acoustic monopole is used to model the unsteady sheet cavitation as a sound source. The analysis comprises intermediate high-pass filtering and integration followed by post-processing the resulting volume time signal. The cavitation volume evolution produced by consecutive blade passages shows well-recognisable steady growth and rapid collapse phases. By means of shape-dependend and time-synchronous sequencing and averaging methods, a representative volume signal of one blade passage has been deduced and several influential parameters have been identified. This allows modelling and manipulating the volume evolution and thus enables further investigations of the associated noise generation by propellers.

KEYWORDS:

• propeller cavitation noise
• sheet cavitation
• pressure fluctuations
• cavitation volume
• shipping noise

Acknowledgements

The analysed raw data of pressure fluctuations and shaft speed were kindly provided by DW-ShipConsult GmbH from its own measurements.

Disclosure statement

No potential conflict of interest was reported by the authors.