Predicting the performance of a high head Francis turbine using a fully implicit mixing plane

Amstutz, O; Aakti, B; Casartelli, Ernesto; Mangani, Luca; Hanimann, Lucian

doi:10.1088/1742-6596/579/1/012009

Cited by 7 publications

(9 citation statements)

References 5 publications

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“…Summary of the applied modeling approaches, meshing, and dimensionless node distance from the boundary (y + ) and the mesh quality. A hexahedral mesh was created in the labyrinth seals by two research groups to investigate the flow leakage losses in the turbine [8,11,13]. Figure 7 shows the mesh of the upper and lower labyrinth seals of the turbine runner.…”

Section: Mesh Creation and Qualitymentioning

confidence: 99%

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Experimental and Numerical Studies of a High-Head Francis Turbine: A Review of the Francis-99 Test Case

2016

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Hydraulic turbines are widely used to meet real-time electricity demands. Computational fluid dynamic (CFD) techniques have played an important role in the design and development of such turbines. The simulation of a complete turbine requires substantial computational resources. A specific approach that is applied to investigate the flow field of one turbine may not work for another turbine. A series of Francis-99 workshops have been planned to discuss and explore the CFD techniques applied within the field of hydropower with application to high-head Francis turbines. The first workshop was held in December 2014 at the Norwegian University of Science and Technology, Norway. The steady-state measurements were conducted on a model Francis turbine. Three operating points, part load, best efficiency point, and high load, were investigated. The complete geometry, meshing, and experimental data concerning the hydraulic efficiency, pressure, and velocity were provided to the academic and industrial research groups. Various researchers have conducted extensive numerical studies on the high-head Francis turbine, and the obtained results were presented during the workshop. This paper discusses the presented numerical results and the important outcome of the extensive numerical studies on the Francis turbine. The use of a wall function assuming equilibrium between the production and dissipation of turbulence is widely used in the simulation of hydraulic turbines. The boundary layer of hydraulic turbines is not fully developed because of the continuously-changing geometry and large pressure gradients. There is a need to develop wall functions that enable the estimation of viscous losses under boundary development for accurate simulations. Improved simulations and results enable reliable estimation of the blade loading. Numerical investigations on leakage flow through the labyrinth seals were conducted. The volumetric efficiency and losses in the seals were determined. The seal leakage losses formulated through analytical techniques are sufficient.

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Section: Mesh Creation and Qualitymentioning

confidence: 99%

“…The maximum difference between the experimental and numerical values is observed for the unsteady pressure amplitude. Thus, the pressure amplitudes were found to be sensitive to the mesh density, time step sizing, turbulence modeling, discretization order, and boundary conditions [6,8,9,11,13,16,20]. [20].…”

Section: Pressurementioning

confidence: 99%

Experimental and Numerical Studies of a High-Head Francis Turbine: A Review of the Francis-99 Test Case

2016

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“…Meshes were created in the labyrinth seals to investigate the flow leakage losses in the turbine by some of the researchers: Amstutz [7], Jošt [8] and Čelič [5]. Close to the labyrinth seals wall, fine mesh was created for improving the velocity profile from the solid boundary by Čelič [5], who used 63 million nodes.…”

Section: Meshmentioning

confidence: 99%

“…The numerical solvers failed to capture harmonic frequency of 15 in the vaneless space at the BEP, observed in the measurement. The pressure amplitudes were found to be sensitive to the mesh density, time step sizing, turbulence modelling, discretization order, and boundary conditions; Čelič [5], Nicolle [6], Amstutz [7], Jošt [8], Buron [11], Stefan [12] and Minakov [13].…”

Section: Pressure Loadingmentioning

confidence: 99%

State of the art in numerical simulation of high head Francis turbines

Trivedi

Cervantes

2016

Renew. Energy Environ. Sustain.

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The Francis-99 test case consists in a high head Francis turbine model, which geometry together with meshes and detailed experimental measurements is freely available at www.francis-99.org. Three workshops were initially planned to exchange experience on numerical investigations of the test case concerning steady state operating conditions, transient operating conditions and fluid structure analysis. The first workshop was held in Trondheim, Norway in December 2014. Some results of the 14 contributions are presented. They are concerned with the influence of the near wall space discretization and turbulence modelling in order to capture hydraulic efficiency, torque, pressure and velocity with a good uncertainty at three operating conditions.

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“…However, a large part of the design of hydraulic turbines still involves steady state simulations due to time constraints For a high head Francis turbine, both the global parameters such as efficiency, torque, etc., and local parameters including pressure fluctuations due to rotor stator interactions are important to the design. In the numerical simulations and design of hydro turbines, several efforts have been devoted [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Blade passage modeling strategy for hydraulic turbine

Gong

Trivedi

Dahlhaug

et al. 2017

IJFMS

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CFD has played a significant role to investigate the performance and improve the design of hydraulic turbines; however, the improvement of CFD method demands powerful computer resources including time, CPU, memory, and commercial licenses. In present work, both global and local parameters of a high head Francis turbine were studied using several geometrical and interface modelling approaches. The aim of the work is to find suitable strategy for designers to simulate the hydraulic turbines to balance the numerical accuracy and the requirement of computational resources. The geometrical modelling approaches include combinations of turbine components such as, spiral casing, distributor, runner and draft tube. The interface modelling approaches includes, stage, Frozen rotor and transient rotorstator types. The study showed that the proper combinations of both approaches can effectively reduce the numerical error.

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Predicting the performance of a high head Francis turbine using a fully implicit mixing plane

Cited by 7 publications

References 5 publications

Experimental and Numerical Studies of a High-Head Francis Turbine: A Review of the Francis-99 Test Case

Experimental and Numerical Studies of a High-Head Francis Turbine: A Review of the Francis-99 Test Case

State of the art in numerical simulation of high head Francis turbines

Blade passage modeling strategy for hydraulic turbine

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