Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

Mössinger, Peter; Jester-Zürker, Roland; Jung, Alexander

doi:10.1088/1742-6596/782/1/012001

Cited by 19 publications

(19 citation statements)

References 6 publications

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“…Li et al [4] conducted CFD analysis of the pressure pulsations in a prototype pump-turbine in turbine mode with different blade numbers. Mössinger et al [5] investigated axial velocity distribution and pressure pulsations in the turbine during two load changes and turbine shutdown processes. Chalghoum et al [6] analyzed the effect of the impeller diameter and number of blades on the pressure evolution in a centrifugal pump during startup process.…”

Section: Introductionmentioning

confidence: 99%

Research on Unsteady Hydraulic Features of a Francis Turbine and a Novel Method for Identifying Pressure Pulsation Transmission Path

Wang

Zhang

Yin

et al. 2019

Water

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It is of significant value to understand the unsteady hydraulic features and pressure pulsation transmission path in the flow channel through a turbine for providing technical support for turbine design and optimization, as well as laying a foundation for analysis of the stability and the coupled vibration of the hydropower house. In this paper, a three-dimensional mechanics–hydraulics–concrete structure coupled numerical model was established to accurately simulate Francis hydraulic machinery, including the high-rotating turbine runner and fixed guide vane, the unsteady flowing water, the structure of the entire flow channel, as well as the dynamic interaction between them. Turbulent hydraulic features of flow condition and pressure pulsation in design operation were explored using the detached eddy simulation (DES) turbulence model. Then, a novel method was proposed to identify the fluid pressure pulsation transmission path based on the time-delayed transfer entropy method and wavelet theory. On basis of time and frequency analysis of pressure calculation results, investigation into identification of pressure pulsation transmission path was performed using the method of traditional transfer entropy and the method adopted in this paper. The pressure pulsation transmission features in the entire flow channel were revealed during operation of the large-scale Francis turbine. The research method and results could not only lay a basis for exploring the structural vibration regularity of the hydropower house but also provide a scientific reference for vibration reduction design of the hydropower house.

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Section: Introductionmentioning

confidence: 99%

Research on Unsteady Hydraulic Features of a Francis Turbine and a Novel Method for Identifying Pressure Pulsation Transmission Path

Wang

Zhang

Yin

et al. 2019

Water

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“…In order to mimic the GVs motion in the simulations, either mesh deformation [28] or re-meshing techniques [29] are usually employed. In this study, the mesh deformation technique was used to rotate the GVs.…”

Section: Guide Vanes Motionmentioning

confidence: 99%

“…Menter's k − ω SST (shear stress transport) model [31] was used to model turbulence. This turbulence model has shown satisfactory results in terms of robustness, stability, and accuracy in several previous hydraulic turbine studies [28,[32][33][34] and transient flow simulations in pipes [35,36]. The automatic near-wall treatment developed by CFX was employed, which automatically switches from a low-Re formulation to wall-functions when the grid is not refined enough near the wall [30].…”

Section: Governing Equations and Boundary Conditionsmentioning

confidence: 99%

Numerical Study of the Winter–Kennedy Flow Measurement Method in Transient Flows

et al. 2020

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This paper explores the possibility of using the Winter–Kennedy (WK) method for transient flow rate measurement in hydraulic turbines. Computational fluid dynamic (CFD) analysis of a numerical model of an axial turbine was carried out for accelerating and decelerating flows. Those were obtained by linearly opening and closing of the guide vanes, respectively, while retaining the inlet pressure constant during the simulations. The behavior of several WK configurations on a cross-sectional plane and along the azimuthal direction of the spiral casing was studied during the transients. The study showed that there are certain WK configurations that are more stable than others. The physical mechanism behind the stability (or instability) of the WK method during transients is presented. Using the steady WK coefficient obtained at the best efficiency point (BEP), the WK method could estimate the transient flow rate with a deviation of about 7.5% and 3.5%, for accelerating and decelerating flow, respectively.

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“…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%

“…Several numerical studies on hydro-turbines have been reported by considering full or partial computational domains, various time-step for transient analysis, and different turbulence models. One way to perform numerical analysis on a hydro-turbine is by considering the complete turbine model, i.e., including the spiral casing, the distributor domain with stay vanes, guide vanes, runner domain, and draft tube [7,[9][10][11][12][13][14][15][16][17][18]. The literature review presented in Table 1 indicates that the standard k-ε turbulence model can predict the numerical results in the complete hydro-turbine model, especially for the Francis turbine.…”

Section: Introductionmentioning

confidence: 99%

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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Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

Cited by 19 publications

References 6 publications

Research on Unsteady Hydraulic Features of a Francis Turbine and a Novel Method for Identifying Pressure Pulsation Transmission Path

Research on Unsteady Hydraulic Features of a Francis Turbine and a Novel Method for Identifying Pressure Pulsation Transmission Path

Numerical Study of the Winter–Kennedy Flow Measurement Method in Transient Flows

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

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