Results 221 to 230 of about 10,024 (247)

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
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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
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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
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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
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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
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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
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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
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Study of Pressure Shock Caused by a Vortex Ring Separated From a Vortex Rope in a Draft Tube Model

Journal of Fluids Engineering, 2017
Operating hydraulic turbines under part- or over-load conditions leads to the development of the precessing vortex rope downstream of the turbine runner. In a regime close to the best efficiency point (BEP), the vortex rope is very unstable because of the low residual swirl of the flow.
S. G. Skripkin, M. A. Tsoy, P. A. Kuibin, S. I. Shtork   +3 more
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Two-Dimensional Numerical Simulation of Vortex Shedding of Multiple Stranded Ropes

Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology, 2019
Abstract The stranded rope is one of the important components of the fishery aquaculture equipment. We investigate the fluid flow through two-dimensional stranded rope by direct simulation of the Navier-Stokes equations. We show that for different kinds of stranded rope structures, there are significant differences in hydrodynamic ...
Xinxin Wang, Liuyi Huang, Yanli Tang, Fenfang Zhao, Peng Sun   +4 more
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Mitigation of swirling flow with a vortex rope by passive installations—Theory, simulations, and experiments

Physics of Fluids, 2022
This work is focused on reduction of swirling in cases from hydraulic machinery and, thus, mitigation of instabilities associated with swirling flow. We study this problem analytically using the torque integral equation, numerically using computational fluid dynamics (CFD) simulations, and experimentally using a swirl generator that generates swirling ...
Ondřej Urban, Michaela Kurková, František Pochylý   +2 more
openaire   +1 more source