000231247 001__ 231247
000231247 005__ 20190812210002.0
000231247 0247_ $$2doi$$a10.1088/1742-6596/813/1/012022
000231247 037__ $$aCONF
000231247 245__ $$aExperimental investigation of the mass flow gain factor in a draft tube with cavitation vortex rope
000231247 269__ $$a2017
000231247 260__ $$c2017
000231247 336__ $$aConference Papers
000231247 520__ $$aAt off-design operating operations, cavitating flow is often observed in hydraulic machines. The presence of a cavitation vortex rope may induce draft tube surge and electrical power swings at part load and full load operations. The stability analysis of these operating conditions requires a numerical pipe model taking into account the complexity of the two-phase flow. Among the hydroacoustic parameters describing the cavitating draft tube flow in the numerical model, the mass flow gain factor, representing the mass excitation source expressed as the rate of change of the cavitation volume as a function of the discharge, remains difficult to model. This paper presents a quasi-static method to estimate the mass flow gain factor in the draft tube for a given cavitation vortex rope volume in the case of a reduced scale physical model of a ν = 0.27 Francis turbine. The methodology is based on an experimental identification of the natural frequency of the test rig hydraulic system for different Thoma numbers. With the identification of the natural frequency, it is possible to model the wave speed, the cavitation compliance and the volume of the cavitation vortex rope. By applying this new methodology for different discharge values, it becomes possible to identify the mass flow gain factor and improve the accuracy of the system stability analysis.
000231247 700__ $$aLandry, C
000231247 700__ $$aFavrel, A
000231247 700__ $$aMüller, A
000231247 700__ $$aYamamoto, K
000231247 700__ $$aAlligné, S
000231247 700__ $$aAvellan, F
000231247 7112_ $$dFebruary 2-3, 2017$$cPorto, Portugal$$aHYPERBOLE Conference
000231247 773__ $$j813$$tJournal of Physics: Conference Series$$k1$$q012022
000231247 909C0 $$xU10309$$pLMH$$0252135
000231247 909CO $$pconf$$pSTI$$ooai:infoscience.tind.io:231247
000231247 917Z8 $$x104417
000231247 937__ $$aEPFL-CONF-231247
000231247 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000231247 980__ $$aCONF