Smith, Tom;
Grech La Rosa, Andrea;
McMorran, Solomon M;
Piggott, Giles;
Joao, Gaivota AN;
(2025)
Cavitation on small craft propellers and its contribution to underwater radiated noise.
In:
Proceedings of the 8th Underwater Acoustics Conference and Exhibition (UACE 2025).
Underwater Acoustics Conference and Exhibition: Halkdiki, Greece.
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Abstract
Cavitation is a major contributor to underwater radiated noise (URN) from commercial ships but less is known about the dynamics, inception speed, and contribution of cavitation to URN for small vessels. Small vessels often use propellers located very close to the free surface and which turn at high speeds. This means that the cavitation dynamics are likely to be different from those on larger ships. Many small vessels are powered by internal combustion outboard engines, which typically expel exhaust gases through the hub, leading to a bubbly hub vortex. In this work, acoustic data from small boat trials are presented alongside underwater camera footage to show how cavitation develops on small high speed propellers and how it contributes to the acoustic signature. The results show that the cavitation inception speeds are typically 5-6 knots, and this is accompanied by a sharp rise in noise across a broad frequency range. Visual footage shows that tip vortex cavitation dominates at low speeds. Results are also presented that provide insights into how the material state of the propeller can influence the cavitation dynamics. Whilst rough and fouled propellers might be assumed to cavitate earlier and hence be louder than their smooth counterparts, it is shown here that this is not always the case. When tip vortex cavitation dominates, small amounts of roughness can actually reduce URN levels by disrupting the formation of the tip vortex.
| Type: | Proceedings paper |
|---|---|
| Title: | Cavitation on small craft propellers and its contribution to underwater radiated noise |
| Event: | 8th Underwater Acoustics Conference and Exhibition (UACE 2025) |
| Open access status: | An open access version is available from UCL Discovery |
| Publisher version: | https://www.uaconferences.org/ |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | propeller cavitation, underwater radiated noise |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10210145 |
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