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RISS 인기검색어
- 검색키워드
- 저자 : Xavier Escaler (검색결과 2 건)
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Experimental and numerical study on the detection of fatigue failure in hydraulic turbines
Xavier Sánchez-Botello,Adolfo de la Torre,Rafel Roig,Esteve Jou,Oscar de la Torre,Javier Ayneto,Xavier Escaler 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10
Detecting fatigue cracks in hydraulic turbine runners is costly, as it requires stopping the unit, emptying it of water and accessing the runner for inspection. Thus, an alternative way based on monitoring the changes of the structural modal response induced by the formation and growth of a crack was investigated. To do so, the crack propagation induced by a resonance was numerically predicted and experimentally machined on a disk-like structure that resembles a Kaplan turbine runner. The analysis of the results shows how the different stages of the fatigue crack growth can be monitored based on the change of the natural frequencies and mode shapes of several specific modes. Based on the obtained results, a structural health monitoring system is being designed to monitor the turbine runner modes of vibration without the need to stop and inspect the unit.
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Dynamic Analysis of Francis Runners - Experiment and Numerical Simulation
Lais, Stefan,Liang, Quanwei,Henggeler, Urs,Weiss, Thomas,Escaler, Xavier,Egusquiza, Eduard Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.4
The present paper shows the results of numerical and experimental modal analyses of Francis runners, which were executed in air and in still water. In its first part this paper is focused on the numerical prediction of the model parameters by means of FEM and the validation of the FEM method. Influences of different geometries on modal parameters and frequency reduction ratio (FRR), which is the ratio of the natural frequencies in water and the corresponding natural frequencies in air, are investigated for two different runners, one prototype and one model runner. The results of the analyses indicate very good agreement between experiment and simulation. Particularly the frequency reduction ratios derived from simulation are found to agree very well with the values derived from experiment. In order to identify sensitivity of the structural properties several parameters such as material properties, different model scale and different hub geometries are numerically investigated. In its second part, a harmonic response analysis is shown for a Francis runner by applying the time dependent pressure distribution resulting from an unsteady CFD simulation to the mechanical structure. Thus, the data gained by modern CFD simulation are being fully utilized for the structural design based on life time analysis. With this new approach a more precise prediction of turbine loading and its effect on turbine life cycle is possible allowing better turbine designs to be developed.
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