Numerical investigation of a high head Francis turbine under steady operating conditions using foam-extend

Lenarcic, Markus; Eichhorn, Markus; Schoder, Stefan; Bauer, Christian

doi:10.1088/1742-6596/579/1/012008

Cited by 10 publications

(6 citation statements)

References 3 publications

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“…The variation is attributed to the omission of the seal leakage losses. Often, numerical results are misleading because the torque and head are over-predicted with an inlet flow boundary condition; see Lenarcic et al [12]. Since the torque generated by the turbine and the available head are related to each other, the hydraulic efficiency is fairly well predicted.…”

Section: Discussionmentioning

confidence: 99%

“…Based on the results presented at the workshop, the differences in quantities, such as head, discharge, and torque were greater than the differences in hydraulic efficiency under the corresponding operating conditions compared to the experimental data. The torque and head values were over-predicted by 13.9% and 19.5% at the BEP, respectively [12]. The hydraulic efficiency showed a difference of´3.9% (see Table 4).…”

Section: Efficiencymentioning

confidence: 94%

“…The final solution can be constructed in time by computing the perturbations at a given time using Equation (12) and adding them to the time-averaged flow. This operation allows obtaining an approximation of the unsteady flow field.…”

Section: Interface Modeling Techniquesmentioning

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: Discussionmentioning

confidence: 99%

Section: Efficiencymentioning

confidence: 94%

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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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“…Based on the results presented in the workshop, the difference in the quantities such as head, discharge, and torque was larger than the difference in hydraulic efficiency at the corresponding operating condition compared to the experimental data. The torque and head values were over-predicted by 13.9% and 19.5% at the BEP, respectively Lenarcic [10]. The hydraulic efficiency showed a difference of À3.9%.…”

Section: Hydraulic Efficiencymentioning

confidence: 90%

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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“…There are several recent studies in literature in which the interactions between runner-guide vane and runner-draft tube are included via frozen rotor interface. For example, Lenarcic et al [16] simulated incompressible turbulent flow for a high head Francis turbine under steady operating conditions which is computed using an open source code. Influences of the coupling methods are compared with each other and with experimental data.…”

Section: Methodsmentioning

confidence: 99%

Rehabilitation of Francis Turbines of Power Plants with Computational Methods

Çelebioğlu¹,

Aradağ²,

Ayli³

et al. 2018

Hittite J. Sci. Eng.

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R ehabilitation of hydraulic turbines of existing power plants is an important topic because of the low performance, poor reliability, frequent maintenance intervals and undesirable cavitation properties of old turbines at the plants. Rehabilitation projects increased worldwide to improve turbine designs and to reach the desired performance characteristics, especially with the improvements in computational power and Computational Fluid Dynamics (CFD) technology. However, rehabilitation of old power plants is often more difficult than the design of the turbines for new power plants since most of the existing parts cannot be altered because some of the parts are buried and the space is limited with the size of the old turbine.Both experimental and numerical methods are common in the design [1] Su et al. [4] computed the three-dimensional turbulent flow in Francis turbines using Large Eddy Simulations (LES). They used unstructured meshes for the spiral case and the runner, while structured meshes were utilized for the remaining components. They found out that cavitation was observed at the suction side of the blade under partial load conditions. Patel et al.[5] also performed three-dimensional, unsteady CFD simulations for Francis turbines. They investigated the effect of partial loading on turbine performance. The A B S T R A C T R ehabilitation of existing hydroelectric power plants (HEPP) by redesigning the hydraulic turbines is usually more elaborate than designing a tailor-made turbine for a new plant. Some of the parts are buried and the space is limited with the size of the old turbine; therefore, this increases the number of constraints imposed on the design. This article presents a Computational Fluid Dynamics (CFD) based rehabilitation procedure involving the state of the art redesign of the turbine of a hydroelectric power plant for better performance at design and off-design conditions of several head and flow rates. Runner and guide vanes of the Francis turbine are designed per the design head and flow rates available for the turbine at the site. The simulations for the designed parts are performed both separately and using all turbine parts as full turbine analyses. Both the design and off-design conditions are simulated for the newly designed and existing turbines for comparison purposes. Cavitation performance of the new design is also determined. The proposed methodology is applicable to any Francis type turbine and any HEPP that needs rehabilitation.

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Numerical investigation of a high head Francis turbine under steady operating conditions using foam-extend

Cited by 10 publications

References 3 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

Rehabilitation of Francis Turbines of Power Plants with Computational Methods

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