Investigation of Rotating Vortex Rope formation during load variation in a Francis turbine draft tube

Sotoudeh, Nahale; Maddahian, Reza; Cervantes, Michel

doi:10.1016/j.renene.2019.11.014

Cited by 53 publications

(33 citation statements)

References 33 publications

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“…An alternative approach to mimic the complete turbine model is by considering the flow-passage approach for the distributor and runner domain [18,19]. The distributor domain (with stay vanes and guide vanes) and runner domain (with main and splitter blades) have a cascade-type arrangement that divides the domains into a passage-like domain [3,18,19]. Amstutz et al [18] performed numerical analysis on the Francis-99 turbine with the spiral casing, distributor domain passage, runner domain passage, and draft tube.…”

Section: Authorsmentioning

confidence: 99%

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Reduced Numerical Modeling of a High Head Francis Turbine Draft Tube at Part Load

Joy¹,

Cervantes²,

Raisee³

2021

IJFMS

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In the present study, a reduced model of the Francis-99 model turbine was investigated numerically at part load operating condition. The reduced model consists of a standalone draft tube domain of the Francis-99 model turbine. Numerical studies performed in the past on nearly complete hydro-turbine models (inclusive of the spiral casing, distributor domains, runner, and draft tube) reportedly consist of a large number of computational grids. This may increase the computational costs and data storage required to perform numerical analysis, which could be a setback for future research on new design concepts and optimization study of the draft tube domain. The reduced model was developed by mapping the phase averaged axial, radial, and tangential velocity profiles from the runner exit to the inlet of the standalone draft tube domain. Additionally, turbulent kinetic energy (k) and turbulent eddy dissipation (ε) variables were also considered for better flow prediction inside the draft tube domain. Two methods for mapping inlet boundary conditions were considered in the present study. In the first method, the entire planar profile of the runner-draft tube interface was considered. In the second method, the variables along a radial profile at the runner exit were considered with an axissymmetric flow assumption over the entire draft tube inlet plane. The numerical results obtained from the Francis-99 reduced model turbine were validated against the numerical model of the NVKS Francis-99 model turbine (with available structured mesh) that was also analysed using the passage flow numerical technique and available experimental results. The results were found to be in reasonable agreement, with each other. The present study could be useful for the future mitigation study of rotating vortex rope by modifying the draft tube domain.

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Section: Authorsmentioning

confidence: 99%

“…Table 1 Summary of numerical analysis performed on hydro-turbines. Several validation studies of the experimental data have been performed in the past using CFD tools on hydro-turbines [7][8][9][11][12][13][14][15][16][17][18][19][20]. A summary of numerical studies performed on hydro-turbines are presented in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Reduced Numerical Modeling of a High Head Francis Turbine Draft Tube at Part Load

Joy¹,

Cervantes²,

Raisee³

2021

IJFMS

Self Cite

View full text Add to dashboard Cite

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“…The solid model of impeller and diffuser are shown in Figure 2. on the other hydraulic machines, including Francis turbine [36][37][38], water turbine [39], and tidal turbine [40]. At present, there are relatively few studies on the influence of end clearance on the performance of ESP.…”

Section: Geometry Modelmentioning

confidence: 99%

“…They found that k-ε and k-ω are most suitable for internal flow and performance prediction. Furthermore, as a powerful simulation method, CFD approach was applied on the other hydraulic machines, including Francis turbine [36][37][38], water turbine [39], and tidal turbine [40].…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of a High-Speed Electrical Submersible Pump with Different End Clearances

Zhou

Wang

Hang

et al. 2020

Water

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The end clearance of the impeller is one of the most important structural parameters in the hydraulic design of a high-speed electrical submersible pump (ESP). In this paper, an ESP with a rotating speed of 6000 r/min was taken as the research object. Numerical calculations were carried out for five different end clearance conditions of 0.1 mm, 0.3 mm, 0.6 mm, 0.9 mm, and 1.2 mm, respectively, to obtain the performance and internal flow field under different situation. The simulation results were verified by the pump performance experiment. It showed that the increase of the end clearance led to a decrease of the head and efficiency of the electrical submersible pump. Through the analysis of the internal flow field, it was found that the existence of the end clearance reduced the flow rate and caused free pre-whirl. With the increase of the end clearance, the phenomenon of de-flow in the diffuser passage was aggravated, which further reduced the performance of the electrical submersible pump. Finally, the reasonable recommended value of the end clearance was given, which facilitated the optimization design and engineering application of the high-speed ESP.

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“…Transient regimes can occur in regions with a PVC, so it is of considerable interest to study the mechanisms of PVC formation in various transient regimes. The research [10] focuses on the dynamics of the PVC formation during the load variation employing transient numerical simulations. The results indicate four flow regimes with different characteristics during PVC formation.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Transient Flow Regimes in a Model Hydroturbine Draft Tube

et al. 2021

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Swirling flow with the formation of a precessing vortex core (PVC) in the draft tube model of a hydroturbine was studied. Experiments were performed on an aerodynamic setup under transient operating conditions of the hydroturbine. The turbine operating conditions were varied by continuously changing the flow rate at a constant runner speed. The transition from the partial load regime, when a precessing vortex core is formed, to the best efficiency point without a core is considered. Applied to this task, a comparison of the windowed Fourier transform with wavelet analysis is given. The dependence of the PVC lifetime in the transient regime correlates with the transient time. It is shown that the velocity profiles and the spectrum of pressure pulsations in transient regimes change quasistatically between part-load operation and the best efficiency point of the turbine. The phase-averaged velocity distributions in the transient regimes show that a transient regime is a sequence of quasisteady regimes.

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Investigation of Rotating Vortex Rope formation during load variation in a Francis turbine draft tube

Cited by 53 publications

References 33 publications

Reduced Numerical Modeling of a High Head Francis Turbine Draft Tube at Part Load

Reduced Numerical Modeling of a High Head Francis Turbine Draft Tube at Part Load

Numerical Investigation of a High-Speed Electrical Submersible Pump with Different End Clearances

Experimental Study of Transient Flow Regimes in a Model Hydroturbine Draft Tube

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