000059061 001__ 59061
000059061 005__ 20190812204857.0
000059061 037__ $$aCONF
000059061 245__ $$aIdentification and Modeling of Pressure Fluctuations of a Francis Turbine Scale Model at Part Load Operation
000059061 260__ $$bInternational Association For Hydraulic Research$$c2004
000059061 269__ $$a2004
000059061 300__ $$a17
000059061 336__ $$aConference Papers
000059061 490__ $$aModel testing$$vA7-1
000059061 520__ $$aScale model of high specific speed Francis turbines may present at upper part load operation under low cavitation number pressure fluctuation in the range 2 to 4 times fn, the rotating frequency. In the framework of the FLINDT project, pressure measurements on the draft tube wall of a Francis turbine scale model at 104 locations revealed such phenomenon at a frequency of almost 2.5 fn. The phase shift analysis of the measured pressure fluctuations in the draft tube at this frequency points out a pressure source located in the inner part of the draft tube elbow. The spectral analysis of the pressure signal at this location shows that there is energy uniformly distributed in the range 0 to 7 fn. This results from impacts of the vortex rope during its precession on the draft tube wall. The wave speed along the draft tube is calculated using the experimental results of the phase shifts and allows modeling the entire test rig with SIMSEN. The simulation of the hydro acoustic behavior of the entire test rig, including the scale model and the piping system, and considering white noise excitation at the pressure source location provides eigen frequencies of the full hydraulic system. An eigen frequency at 2.46 fn is identified and the corresponding mode shape agrees well with the experimental results. A forced excitation composed of the synchronous pressure fluctuation measured in the draft tube cone added to pressure impulsion peaks at the vortex rope precession frequency is also simulated. This excitation represents the synchronous part of the vortex rope excitation and the energy provided by the impacts on the draft tube wall. The analysis of the resulting pressure fluctuation in the entire test rig shows significant pressure amplitude mainly at 2.46fn, which evidences the excitation mechanism.
000059061 542__ $$fCC BY
000059061 700__ $$aNicolet, Christophe
000059061 700__ $$aArpe, Jorge
000059061 700__ $$g104417$$aAvellan, François$$0241012
000059061 7112_ $$dJune 29 – July 2, 2004$$cStockholm, Sweden$$a22nd IAHR Symposium on Hydraulic Machinery and Systems
000059061 773__ $$tProceedings of the 22nd IAHR Symposium on Hydraulic Machinery and Systems, Stockholm, Sweden$$q1-17$$j1
000059061 8564_ $$zn/a$$uhttps://infoscience.epfl.ch/record/59061/files/CODYPU_04_1.pdf$$s951171
000059061 8564_ $$uhttps://infoscience.epfl.ch/record/59061/files/Identification%20and%20Modeling%20of%20Pressure%20Fluctuations%20of%20a%20Francis%20Turbine%20Scale%20Model%20at%20Part%20Load%20Operation.pdf$$s981656
000059061 8564_ $$xpdfa$$uhttps://infoscience.epfl.ch/record/59061/files/Identification%20and%20Modeling%20of%20Pressure%20Fluctuations%20of%20a%20Francis%20Turbine%20Scale%20Model%20at%20Part%20Load%20Operation.pdf?subformat=pdfa$$s2083104
000059061 8560_ $$femilie.reynaud@epfl.ch
000059061 909C0 $$xU10309$$pLMH$$0252135
000059061 909CO $$ooai:infoscience.tind.io:59061$$qGLOBAL_SET$$pconf$$pSTI
000059061 937__ $$aLMH-CONF-2004-003
000059061 970__ $$a1445/LMH
000059061 973__ $$rREVIEWED$$aEPFL
000059061 980__ $$aCONF