000205214 001__ 205214
000205214 005__ 20190812205825.0
000205214 02470 $$2ISI
000205214 0247_ $$a10.1088/1755-1315/22/3/032035$$2doi
000205214 02470 $$a000347441900093
000205214 037__ $$aCONF
000205214 245__ $$aHydro-acoustic resonance behavior in presence of a precessing vortex rope: observation of a lock-in phenomenon at part load Francis turbine operation
000205214 260__ $$c2014$$bIop Publishing Ltd$$aBristol
000205214 269__ $$a2014
000205214 300__ $$a9
000205214 336__ $$aConference Papers
000205214 490__ $$aIOP Conference Series-Earth and Environmental Science$$v22
000205214 520__ $$aFrancis turbines operating at part load condition experience the development of a cavitating helical vortex rope in the draft tube cone at the runner outlet. The precession movement of this vortex rope induces local convective pressure fluctuations and a synchronous pressure pulsation acting as a forced excitation for the hydraulic system, propagating in the entire system. In the draft tube, synchronous pressure fluctuations with a frequency different to the precession frequency may also be observed in presence of cavitation. In the case of a matching between the precession frequency and the synchronous surge frequency, hydro-acoustic resonance occurs in the draft tube inducing high pressure fluctuations throughout the entire hydraulic system, causing torque and power pulsations. The risk of such resonances limits the possible extension of the Francis turbine operating range. A more precise knowledge of the phenomenon occurring at such resonance conditions and prediction capabilities of the induced pressure pulsations needs therefore to be developed. This paper proposes a detailed study of the occurrence of hydro-acoustic resonance for one particular part load operating point featuring a well-developed precessing vortex rope and corresponding to 64% of the BEP. It focuses particularly on the evolution of the local interaction between the pressure fluctuations at the precession frequency and the synchronous surge mode passing through the resonance condition. For this purpose, an experimental investigation is performed on a reduced scale model of a Francis turbine, including pressure fluctuation measurements in the draft tube and in the upstream piping system. Changing the pressure level in the draft tube, resonance occurrences are highlighted for different Froude numbers. The evolution of the hydro-acoustic response of the system suggests that a lock-in effect between the excitation frequency and the natural frequency may occur at low Froude number, inducing a hydro-acoustic resonance in a random range of cavitation numbers.
000205214 542__ $$fCC BY
000205214 700__ $$aFavrel, A.
000205214 700__ $$aLandry, C.
000205214 700__ $$aMüller, Andres$$0244116
000205214 700__ $$aYamamoto, K.
000205214 700__ $$aAvellan, F.$$0241012$$g104417
000205214 7112_ $$dSeptember 22-26, 2014$$cMontréal, Québec, Canada$$a27th IAHR Symposium on Hydraulic Machinery and Systems (IAHR 21014)
000205214 7112_ $$dSeptember 22-26, 2014$$cMontréal, Canada$$a27th IAHR Symposium on Hydraulic Machinery and Systems 
000205214 720_1 $$aDesy, N$$eed.
000205214 720_1 $$aDeschenes, C$$eed.
000205214 720_1 $$aGuibault, F$$eed.
000205214 720_1 $$aPage, M$$eed.
000205214 720_1 $$aTurgeon, M$$eed.
000205214 720_1 $$aGiroux, Am$$eed.
000205214 773__ $$j22$$tProceedings of the 27th IAHR Symposium on Hydraulic Machinery and Systems (IAHR 2014)
000205214 8564_ $$uhttps://infoscience.epfl.ch/record/205214/files/Hydro-acoustic%20resonance%20behavior%20in%20presence%20of%20a%20precessing%20vortex%20rope%3A%20observation%20of%20a%20lock-in%20phenomenon%20at%20part%20load%20Francis%20turbine%20operation.pdf$$s371771
000205214 8564_ $$xpdfa$$uhttps://infoscience.epfl.ch/record/205214/files/Hydro-acoustic%20resonance%20behavior%20in%20presence%20of%20a%20precessing%20vortex%20rope%3A%20observation%20of%20a%20lock-in%20phenomenon%20at%20part%20load%20Francis%20turbine%20operation.pdf?subformat=pdfa$$s1661029
000205214 8560_ $$femilie.reynaud@epfl.ch
000205214 909C0 $$xU10309$$pLMH$$0252135
000205214 909CO $$ooai:infoscience.tind.io:205214$$qGLOBAL_SET$$pconf$$pSTI
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000205214 917Z8 $$x104417
000205214 937__ $$aEPFL-CONF-205214
000205214 973__ $$rREVIEWED$$aEPFL
000205214 980__ $$aCONF