Manipulation of the swirling flow instability in hydraulic turbine diffuser by different methods of water injection
V. Kaplan Dept. of Fluid Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, Brno 61669, Czech Republic
2 Research Group in Fluid Dynamics, School of Mechanical Engineering, Universidad del Valle, Calle 13 No. 100-00, Cali, Colombia
* Corresponding author: firstname.lastname@example.org
Published online: 4 June 2018
Vortex rope, which induces substantial pressure pulsations, arises in the draft tube (diffuser) of Francis turbine for off-design operating conditions. Present paper focuses on mitigation of those pulsations using active water jet injection control. Several modifications of the original Susan-Resiga’s idea were proposed. All modifications are driven by manipulation of the shear layer region, which is believed to play important role in swirling flow instability. While some of the methods provide results close to the original one, none of them works in such a wide range. Series of numerical experiments support the idea that the necessary condition for vortex rope pulsation mitigation is increasing the fluid momentum along the draft tube axis.
© The Authors, published by EDP Sciences, 2018
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