The Study of Propeller Cavitation Noise Using Cross-Correlation Methods,
DEFENCE RESEARCH ESTABLISHMENT ATLANTIC DARTMOUTH (NOVA SCOTIA)
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This paper presents a technique for the study of the mechanisms responsible for the generation of noise from cavitating propellers. The experimental method, which involves the cross-correlation of the pressure gradient in the near-field of the propeller with far-field sound, allows the determination of the spatial distributuion of acoustic source strength on and near the cavitating propeller. Cross-Correlations performed at a number of points along a track parallel to the axis of the propeller indicate that the majority of noise from propellers producing vortex cavitation originates from the region of vortex collapse. A bubble cavitation propeller showed a region of relatively constant source strength distribution from the propeller disk region downstream to the point of vortex collapse. All propellers tested showed a slow decay of acoustic source strength with downstream distance after vortex collapse. This result may be indicative of significant amounts of sound being produced by bubble rebounds in the propeller wake.
- Marine Engineering