Modal behavior of a reduced scale pump turbine impeller. Part II: Numerical simulation

A numerical simulation has been carried out to analyze the modal behavior of a reduced scale pump-turbine impeller. The simulation has been done using FEM method, in air and in water. The same boundary conditions than in the experiment were considered: free body in air and free body submerged in a reservoir of water. A sensitivity analysis to determine the influence of the number of elements was done. The influence of the input parameters was also taken into account. Finally, a mesh with 165000 elements for the impeller in air and of 508676 for the impeller in water was used. The results obtained with the simulation have been compared with the experimental ones (paper 1). Both the natural frequency values and the mode-shapes were compared. The numerical results showed small deviation from experiment in the first modes in modes with low modal density. In some coupled modes been found. With the updated model the mode-shapes have been analyzed. Some modes with high modal density have been found. As indicated in the experiment, the effect of the added mass reduces the natural frequencies and also changes the characteristics of the coupled modes.


Published in:
25th Symposium on Hydraulic Machinery and Systems, 1, 1-9
Presented at:
25th IAHR Symposium on Hydraulic Machinery and Systems, Timisoara, Romania, September 20-24, 2010
Year:
2010
Publisher:
International Association For Hydraulic Research
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 Record created 2018-05-19, last modified 2019-08-12

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