Investigation of Hull Excitation Characteristics on CFAV QUEST
Technical memo no. 98/208
DEFENCE RESEARCH ESTABLISHMENT ATLANTICDARTMOUTH (NOVA SCOTIA)
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The NSMB Co-operative Research Ships organization is investigating various aspects of hull excitation from highly skewed propellers. As part of this effort DREA measured hull excitations and made concurrent cavitation observations onboard CFAV QUEST. Results from these are presented and discussed. Varying amounts of sheet, leading edge vortex, tip vortex and hub vortex cavitation were observed. Bursting of the vortex cavitation was prominent in many cases. As ship speed and the amount of cavitation increased, so did the level of the higher harmonics of blade rate in the hull excitation spectra. There was some limited correlation between the appearance of the different forms of cavitation and the appearance of specific harmonics in the hull excitation. There was also data that indicated that no simple correlation would be possible. For instance, the harmonics at five and six times blade rate depended on the amount rather than the nature of the cavitation.
- Marine Engineering