Title:
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Modal behavior of a reduced scale pump-turbine impeller. Part I. Experiments
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Author:
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Escaler Puigoriol, Francesc Xavier; Hutter, J.K.; Egusquiza Estévez, Eduard; Farhat, Mohamed; Avellan, F.
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Other authors:
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Universitat Politècnica de Catalunya. Departament de Mecànica de Fluids; Universitat Politècnica de Catalunya. FLUIDS - Enginyeria de Fluids |
Abstract:
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An experimental investigation has been carried out to quantify the effects of
surrounding fluid on the modal behavior of a reduced scale pump-turbine impeller. The modal
properties of the fluid-structure system have been obtained by Experimental Modal Analysis
(EMA) with the impeller suspended in air and inside a water reservoir. The impeller has been
excited with an instrumented hammer and the response has been measured by means of
miniature accelerometers. The Frequency Response Functions (FRF’s) have been obtained
from a large number of impacting positions in order to ensure the identification of the main
mode shapes. As a result, the main modes of vibration have been well characterized both in air
and in water in terms of natural frequency, damping ratio and mode shape. The first mode is
the 2 Nodal Diameter (ND), the second one is the 0ND and the following ones are the 3ND
coupled with the 1ND. The visual observation of the animated mode shapes and the level of the
Modal Assurance Criterion (MAC) have permitted to correlate the homologous modes of
vibration of the fluid-structure system in air and in water. From this comparison the added
mass effect on the natural frequencies and the fluid effect on the damping ratios have been
quantified for the most significant modes. With the surrounding water, the natural frequencies
decrease in average by 10%. On the other hand, the damping ratios increase in average by
0.5%. In any case, the damping ratio appears to decrease with the frequency value of the mode |
Subject(s):
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-Àrees temàtiques de la UPC::Enginyeria mecànica::Mecànica de fluids -Àrees temàtiques de la UPC::Enginyeria mecànica::Mecànica de fluids::Màquines hidràuliques i de fluids -Fluid mechanics and its applications -Hydraulic turbines -Mecànica de fluids -Turbines |
Rights:
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Attribution-NonCommercial-NoDerivs 3.0 Spain
http://creativecommons.org/licenses/by-nc-nd/3.0/es/ |
Document type:
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Article - Published version Conference Object |
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