Results 181 to 190 of about 448 (209)

Experimental Investigation Of Couple Precessing Vortex Ropes In A Hydraulic Vortex

Siberian Journal of Physics, 2016
The work is devoted to the experimental study of the interaction of the precessing vortex pair in the hydrodynamic vortex chamber. Swirling flow was created by a 12 tangentially directed rectangular nozzles. Design swirl number was varied in the range 0÷6.6 based on the geometry of the swirl device.
Sergey Skripkin, Sergey Dremov, Sergey Shtork, Ivan Kabardin   +3 more
openaire   +1 more source

Numerical Simulation of the Rotating Vortex Rope with Code_Saturne

2019 International Conference on ENERGY and ENVIRONMENT (CIEM), 2019
The paper presents numerical simulations of the rotating vortex rope (RVR) inside a Francis turbine draft tube. The computational fluid dynamics (CFD) calculations were carried out using the Code_Saturne software. The geometry of the turbine was obtained from the Francis-99 workshops. The mesh files provided for the Francis-99 workshop II were modified
Robert Mitrut, Diana Maria Bucur, Georgiana Dunca, Michel J. Cervantes   +3 more
openaire   +1 more source

Part Load Vortex Rope as a Global Unstable Mode

Journal of Fluids Engineering, 2017
Renewable energy sources (RES) have reached 23.7% of the worldwide electrical generation production in 2015. The hydraulic energy contribution amounts to 16.6% and comes mainly form large-scale hydropower plants, where Francis turbines represents 60% of the generating units. However, the future massive development of RES will require more advanced grid
Pasche, Simon, Avellan, François, Gallaire, François   +2 more
openaire   +2 more sources

Simulations and Measurements of Pressure Oscillations Caused by Vortex Ropes

Journal of Fluids Engineering, 2006
Pressure oscillations caused by vortex rope were measured in the draft tube of a prototype Francis turbine. The three-dimensional, unsteady Reynolds-averaged Navier-Stokes equations with the RNG κ−ϵ turbulence model were solved to model the flow within the entire flow path of the prototype hydraulic unit including the guide vanes, the runner, and the ...
Zhengwei Wang, Lingjiu Zhou
openaire   +1 more source

Effect of water jet area on mitigation of vortex rope in a Francis turbine

Physics of Fluids, 2023
The rotating vortex rope (RVR) is normally formed at part load operating conditions, which develops flow instability in the draft tube (DT) cone of a Francis turbine. The detrimental effects of RVR reduce the life and performance of the turbine. The present work mitigates RVR through axial water jet injection in the DT cone.
Sandeep Kumar, Bhupendra K. Gandhi
openaire   +1 more source

Spatio-temporal evolution mechanism of cavitation vortex ropes in a swirling flow

Physics of Fluids, 2021
Cavitation vortex rope widely occurs in hydraulic machinery, leading to the decrease in performance characteristic and increase in pressure fluctuation. The objective of this study was to explore the generation and transformation of cavitation vortex ropes in a swirling flow.
Deyou Li, Zhipeng Ren, Liang Yu, Qi Yang, Hongjie Wang   +4 more
openaire   +1 more source

Model for Vortex Rope Dynamics in Francis Turbine Outlet

1996
The present communication deals with the simulation of the vortex rope present in the outlet of a Francis turbine when operating at partial load regimes This approach is not devoted to the analysis of a complete turbomachinery system but rather to develop a rigorous mathematical analysis for a local phenomenon of practical relevance, We synthesise the ...
G. Pedrizzetti, G. Angelico
openaire   +1 more source

Cavitating vortex rope in a diffuser at different operation conditions

Physics of Fluids
A self-induced instability known as vortex rope enhanced by cavitation usually occurs at part load operation conditions in the draft tube and negatively affects the normal operation of Francis turbines. In the present study, the Francis turbine draft tube was simplified and modeled as a diffuser with swirling flow to analyze and understand the flow ...
Diana Puga, Chen Geng, Ziyang Wang, Xianwu Luo   +3 more
openaire   +1 more source

Vortex Rope Formation in a High Head Model Francis Turbine

Journal of Fluids Engineering, 2017
Francis turbine working at off-design operating condition experiences high swirling flow at the runner outlet. In the present study, a high head model Francis turbine was experimentally investigated during load rejection, i.e., best efficiency point (BEP) to part load (PL), to detect the physical mechanism that lies in the formation of vortex rope. For
Rahul Goyal, Michel J. Cervantes, B. K. Gandhi   +2 more
openaire   +1 more source

Optimal Control of Part Load Vortex Rope in Francis Turbines

Journal of Fluids Engineering, 2019
The mitigation of the precessing vortex core developing in the draft tube of Francis turbines operating under part load conditions is crucial to increase the operation flexibility of these hydraulic machines to balance the massive power production of intermittent energy sources.
Pasche, Simon, Avellan, François, Gallaire, François   +2 more
openaire   +2 more sources