000231158 001__ 231158
000231158 005__ 20181203024826.0
000231158 022__ $$a1814-2079
000231158 0247_ $$a10.1080/00221686.2017.1356758$$2doi
000231158 02470 $$2DOI$$a10.1080/00221686.2017.1356758
000231158 037__ $$aARTICLE
000231158 245__ $$aNew insight in Francis turbine cavitation vortex rope: role of the runner outlet flow swirl number
000231158 260__ $$c2018-05-04
000231158 269__ $$a2018-05-04
000231158 336__ $$aJournal Articles
000231158 520__ $$aAt part load operation, Francis turbines experience the development of a cavitation vortex rope in the draft tube, whose precession acts as a pressure excitation source. In case of resonance, the resulting pressure pulsations lead to unacceptable torque and power fluctuations on the prototype machine, putting at risk the system stability. However, the accurate prediction of resonance conditions at the prototype scale remains challenging since it requires a proper hydro-acoustic modelling of the draft tube cavitation flow. Furthermore, both the head and discharge values have an impact on the precession frequency of the vortex and the natural frequency of the system. The present paper demonstrates for the first time that the influence of both parameters on the frequencies of interest can be represented by a single parameter, the swirl number. Its analytical expression is derived as a function of the operating parameters of the machine. It is used to establish empirical laws enabling the determination of both frequencies and finally the operating parameters in resonance conditions on the complete part load operating range at the model scale. The methodology presented in this paper represents a decisive step towards the prediction of resonances on the complete part load operating range of the prototype.
000231158 6531_ $$aCavitation
000231158 6531_ $$aFrancis turbine
000231158 6531_ $$ahydro-acoustic resonance
000231158 6531_ $$apart load
000231158 6531_ $$aswirl number
000231158 6531_ $$avortex rope
000231158 700__ $$aFavrel, Arthur
000231158 700__ $$g183522$$aGomes Pereira Junior, Joao$$0249112
000231158 700__ $$g170545$$aLandry, Christian$$0245304
000231158 700__ $$aMüller, Andres
000231158 700__ $$aNicolet, Christophe
000231158 700__ $$aAvellan, François
000231158 773__ $$j56$$tJournal of Hydraulic Research$$k3$$q367-379
000231158 8560_ $$ffrancois.avellan@epfl.ch
000231158 909C0 $$xU10309$$0252135$$pLMH
000231158 909CO $$pSTI$$particle$$ooai:infoscience.tind.io:231158
000231158 917Z8 $$x104417
000231158 937__ $$aEPFL-ARTICLE-231158
000231158 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000231158 980__ $$aARTICLE