期刊名称：IOP Conference Series: Earth and Environmental Science
印刷版ISSN：1755-1307
电子版ISSN：1755-1315
出版年度：2019
卷号：240
期号：2
页码：1-9
DOI：10.1088/1755-1315/240/2/022053
出版社：IOP Publishing
摘要：When operating under high load conditions, Francis turbines tend to develop a typical central vortex located under the runner cone. Usually, this central vortex has an axisymmetric main part with helicoidal tail. Under cavitating conditions, this central vapor cavity may become unstable, generating synchronic pressure pulsations (known as self-excited oscillations) which propagate into the entire machine. The volume of the vapor cavity is a relevant feature as it influences the frequency of these pressure pulsations. Numerical flow simulations together with model test measurements and visualizations allow the characterization of the high load vortex pattern developed under different operating and Sigma plant conditions. In this work, model tests and transient two-phase CFD simulations were carried out for a medium-head Francis model scale operating under high load conditions. The vortex instability zone measured and numerical simulated on model scale is presented.
