Prediction of the precessing vortex core in the Francis-99 draft tube under off-design conditions by using Liutex/Rortex method  

作　　者：Cong Trieu Tran Xin-ping Long Bin Ji Chaoqun Liu 

机构地区：[1]State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan 430072,China [2]School of Power and Mechanical Engineering,Wuhan University,Wuhan 430072,China [3]Facullty of Hydraulic Engineering National University of Civil Engineering,55 GiaiPhong,Hanoi,Vietnam [4]Department of Mathematics,University of Texas at Arlington,Arlington 76019,USA

出　　处：《Journal of Hydrodynamics》2020年第3期623-628,共6页水动力学研究与进展B辑（英文版）

摘　　要：The turbulent flow in the draft tube of a Francis turbine is very complicated while working under off-design conditions. Although the off-design conditions were widely studied, the vortex core line in the draft tube of a Francis turbine with splitter blades is not well understood, especially the vortex rope property. This letter presents a prediction of the behavior of the vortex rope in the draft tube of the Francis-99 turbine obtained by the computational fluid dynamics (CFD), where the Liutex/Rortex method, as the most recent vortex definition, is applied to analyze the periodical precession of the vortex rope in the draft tube cone. The advantage of this Liutex/Rortex method is shown by its enhanced ability to represent the vortex rope structurewith the vortex-core lines. Furthermore, since it seems to be very hard to define a sharp boundary surface for the whole vortex structure, it is advantageousfocusing only on the vortex core line,by which different vortex structures can be clearly differentiated. The evolution of the vortex core and the process of the vortex breakdown in the draft tube are revealed, which might help to comprehend the development of the turbulent flow in the draft tube.

关 键 词：Cavitating vortex rope Francis turbine Liutex/Rortex method off-design condition vortex core line 

分 类 号：TV13[水利工程—水力学及河流动力学]