Technical gazette, Vol. 26 No. 6, 2019.
Original scientific paper
https://doi.org/10.17559/TV-20190316042929
Simulation and Analysis of Cavitating Flow in the Draft Tube of the Francis Turbine with Splitter Blades at Off-Design Condition
CongTrieu Tran
; (1) State Key Lab of Water Resources and Hydropower Engineering Science, School of Power and Mechanical Engineering, Wuhan University, Hubei 430072, China / (2) Hubei Key Laboratory of Waterjet Theory and New Technology, Wuhan University, Wuhan 430072, Ch
Bin Ji
; (1) State Key Lab of Water Resources and Hydropower Engineering Science, School of Power and Mechanical Engineering, Wuhan University, Hubei 430072, China / (2) Hubei Key Laboratory of Waterjet Theory and New Technology, Wuhan University, Wuhan 430072, Ch
Xinping Long*
; (1) State Key Lab of Water Resources and Hydropower Engineering Science, School of Power and Mechanical Engineering, Wuhan University, Hubei 430072, China / (2) Hubei Key Laboratory of Waterjet Theory and New Technology, Wuhan University, Wuhan 430072, Ch
Abstract
Hydraulic plants are required to operate with wider operating range to cover the variants of power outputs into the electrical grid. Although there have been many studies of off-design conditions, studies of cavitating draft tube vortices at the Francis turbine with splitter blades are limited, and the cavitating property is not yet well comprehended. This study presents a prediction of the cavitating characteristics in the Francis-99 draft tube obtained by numerical analysis using the Zwart mass transfer model and shear-stress transport (SST) model. The shape characteristics of two types of cavitating vortex rope (spiral and columnar) and its influence on the cavitation development in the runner blades are analyzed. The link between cavitation with the vorticity is further highlighted by the vorticity transport equation (VTE). The result indicates that the runner cavitating is symmetric for both types of cavitating vortex ropes, and cavitation is significantly improved when a runner with splitter blade is used.
Keywords
cavitating vortex rope; Francis turbine; numerical simulation; off-design condition; splitter blades
Hrčak ID:
228511
URI
Publication date:
27.11.2019.
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