Numerical modeling of flow in the Francis-99 turbine with Reynolds stress model and detached eddy simulation method

Минаков, А. В.; Sentyabov, A. V.; Platonov, D. V.; Дектерев, А. А.; Gavrilov, A. A.

doi:10.1088/1742-6596/579/1/012004

Cited by 16 publications

(18 citation statements)

References 3 publications

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“…Doerfler [2], Alligne et al [6], comprehensive experimental data for hydroturbines are still scarce, apart from mean velocity and second-moment turbulence statistics measured at selected locations in laboratory models of some popular turbine types [7][8]. On the other hand, there are still many open questions regarding the numerical simulation of flows in turbines of realistic configuration and practical relevance.…”

Section: Introductionmentioning

confidence: 99%

Francis-99 turbine numerical flow simulation of steady state operation using RANS and RANS/LES turbulence model

Минаков

Platonov

Sentyabov

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. We performed numerical simulation of flow in a laboratory model of a Francis hydroturbine at three regimes, using two eddy-viscosity-(EVM) and a Reynolds stress (RSM) RANS models (realizable k-ε, k-ω SST, LRR) and detached-eddy-simulations (DES), as well as large-eddy simulations (LES). Comparison of calculation results with the experimental data was carried out. Unlike the linear EVMs, the RSM, DES, and LES reproduced well the mean velocity components, and pressure pulsations in the diffusor draft tube. Despite relatively coarse meshes and insufficient resolution of the near-wall region, LES, DES also reproduced well the intrinsic flow unsteadiness and the dominant flow structures and the associated pressure pulsations in the draft tube.

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Section: Introductionmentioning

confidence: 99%

Francis-99 turbine numerical flow simulation of steady state operation using RANS and RANS/LES turbulence model

Минаков

Platonov

Sentyabov

et al. 2017

J. Phys.: Conf. Ser.

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“…The obtained results are then rotated with the runner rotation speed and as such imposed as the inflow field as the inlet into the draft tube. The earlier test calculations proved that this approach is credible for describing the integral flow characteristics including the dominant flow pulsations [4,10,11]. A comparison with the computationally more demanding method using sliding meshes showed that for this type flows with a focus on draft tube dynamics the results are almost the same.…”

Section: Turbulence Models Consideredmentioning

confidence: 88%

“…The models were benchmarked against the experimental data (partly reported by Minakov et al 2014), as well as against the present reference LES, run on a fine grid with 19.3 million cells. We discuss the flow patterns and vortical structure in the turbine draft tube (DT) and its impact on flow stability and pressure pulsations, especially at part loads characterized by unsteady twin helix ropes.…”

Section: Introductionmentioning

confidence: 99%

Vortex ropes in draft tube of a laboratory Kaplan hydroturbine at low load: an experimental and LES scrutiny of RANS and DES computational models

Минаков

Litvinov

Шторк

et al. 2017

Journal of Hydraulic Research

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-We performed numerical simulation complemented by experiments of flow in a 60:1 scaled-down laboratory model of a Kaplan hydroturbine at a part load of about 40% nominal flowrate, using two eddyviscosity-(EVM) and a Reynolds stress (RSM) RANS models (realizable k-, k- SST, LRR) and detachededdy-simulations (DES), all on 2M (million) and 6M grid cells, as well as large-eddy simulations (LES) on 6M and 19.3M grids. Unlike the linear EVMs, the RSM, DES (on 2M grid), and LES (on 6M grid) reproduced well the mean velocity components, the rsm of their fluctuations and pressure pulsations in the diffusor draft tube. Despite relatively coarse meshes and insufficient resolution of the near-wall region, LES, DES and RSM also reproduced well the intrinsic flow unsteadiness and the dominant flow structures, all capturing a twin-rope pattern and the associated pressure pulsations in the draft tube. The EVM URANS on 2M grid could not maintain unsteady solution, but did so on a finer grid of 6 M, resulting in improved mean-flow patterns, but still failing to capture the twin-helix structures and the associated pressure pulsations.

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“…The maximum mesh density for the complete turbine generated approximately 48 million nodes [8]. Total nine research groups [6,[9][10][11][12][13][14][15][16] have performed their own mesh scaling test as stated in Table 3, "Mesh scaling test". The simulations were performed after the mesh scaling test.…”

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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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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Numerical modeling of flow in the Francis-99 turbine with Reynolds stress model and detached eddy simulation method

Cited by 16 publications

References 3 publications

Francis-99 turbine numerical flow simulation of steady state operation using RANS and RANS/LES turbulence model

Francis-99 turbine numerical flow simulation of steady state operation using RANS and RANS/LES turbulence model

Vortex ropes in draft tube of a laboratory Kaplan hydroturbine at low load: an experimental and LES scrutiny of RANS and DES computational models

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

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