Experimental study on the influence of vibration amplitude on the fluid damping of a submerged disk
Accurate determination of modal parameters for disk-like structures submerged in heavy fluids is a topic of interest in many fields. For instance, some type of hydraulic turbomachinery can be modelled as disk structures due to the similarity in their mode shapes. Although in the recent years many st...
| Autores: | , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2023 |
| 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:2117/396865 |
| Acceso en línea: | https://hdl.handle.net/2117/396865 https://dx.doi.org/10.1016/j.jsv.2023.118099 |
| Access Level: | acceso abierto |
| Palabra clave: | Fluid mechanics Fluid dynamics Vibration Fluid damping Fluid structure interaction Vibrating disk Natural frequency Mode shape Resonance Mecànica de fluids Dinàmica de fluids Vibració Àrees temàtiques de la UPC::Enginyeria mecànica::Mecànica de fluids |
| Sumario: | Accurate determination of modal parameters for disk-like structures submerged in heavy fluids is a topic of interest in many fields. For instance, some type of hydraulic turbomachinery can be modelled as disk structures due to the similarity in their mode shapes. Although in the recent years many studies have analyzed and correctly predicted the fluid added mass effect on the natural frequencies and mode shapes of these types of structures, it is particularly challenging to determine fluid damping and characterize its most influential effects. In this article, the influence of vibration amplitude on the fluid damping ratio of a submerged disk, when the disk gets close to a rigid wall, is analytically and experimentally studied. Particularly, the first diametrical modes of the disk have been analyzed at different vibration amplitudes and at very small distances away from a rigid surface. The disk is put in a resonant state by means of a piezoelectric patch generating a harmonic excitation and the response is measured by means of a Laser Doppler Vibrometer (LDV). The damping ratio is obtained directly from the vibrating free decay following a sudden stop of the excitation. It is shown that the fluid damping ratio values are related to the vibration amplitude: there is a trend of increasing damping ratio as the amplitude of the vibration increases. This effect is found to be much larger for small distances between the disk and the rigid surface. |
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