Numerical Investigation into the Effect of Sound Speed in Attached Cavitation on Hydrofoil Modes of Vibration
It has been found recently that the dynamic behavior of a cavitating hydrofoil is di erent from that in pure water in that, not only are the natural frequencies di erent, but the mode shapes may also change. In order to elucidate the mechanism behind this phenomenon, finite element simulations were...
| Autores: | , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/133639 |
| Acceso en línea: | https://hdl.handle.net/2117/133639 https://dx.doi.org/10.3390/en12091758 |
| Access Level: | acceso abierto |
| Palabra clave: | Turbines Hydrofoil Natural frequencies Mode shapes Sound speed Cavitation Mecànica de fluids Àrees temàtiques de la UPC::Enginyeria mecànica::Mecànica de fluids |
| Sumario: | It has been found recently that the dynamic behavior of a cavitating hydrofoil is di erent from that in pure water in that, not only are the natural frequencies di erent, but the mode shapes may also change. In order to elucidate the mechanism behind this phenomenon, finite element simulations were carried out based on acoustic–structure coupling equations. It was found that the structure and acoustic modes exhibit mode transitions with the variation of the sound speed in the cavity. Further, the mode transition was caused by coupling of the structure with the acoustic modes, which was induced by the vapor mode. The amplitude of the vibration near the mode transition point was high and the mode shape was easily excited. Moreover, with the change of the sound speed in the cavity, the di erent distributions of the acoustic pressure mode resulted in di erent structure mode shapes, even on the same transition line. Considering this, a sheet cavitation was simulated by a small change of the void fraction to 0.999 and the sound speed from 343 to 275 m/s to obtain good agreement with the experimental data. Both results showed that the second bending mode under cavitation conditions became a bending–torsion coupled mode. |
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