Vortical structures and pressure pulsations in draft tube of a Francis-99 turbine at part load: RANS and hybrid RANS/LES analysis

Gavrilov, A. A.; Sentyabov, A. V.; Дектерев, А. А.; Hanjalić, K.

doi:10.1016/j.ijheatfluidflow.2016.05.007

Cited by 32 publications

(11 citation statements)

References 16 publications

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Section: Mathematical Model and Numerical Methodsmentioning

confidence: 99%

“…Standard wall function was used in case of eddy viscosity model and a blended technique [13] was used in case of RSM model. The simulations were performed by means of in-house CFD code SigmaFlow [12,13] which is developed in the Institute of thermophysics, Novosibirsk. The code was designed for solving of hydrodynamics and thermophysics problems in industrial applications and scientific investigations in the field of numerical simulation of turbulence, cavitation, non-Newtonian flow and heat transfer.…”

Section: Mathematical Model and Numerical Methodsmentioning

confidence: 99%

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Steady state operation simulation of the Francis-99 turbine by means of advanced turbulence models

Gavrilov

Дектерев

Минаков

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. The paper presents numerical simulation of the flow in hydraulic turbine based on the experimental data of the II Francis-99 workshop. The calculation domain includes the wicket gate, runner and draft tube with rotating reference frame for the runner zone. Different turbulence models such as k-ω SST, ζ-f and RSM were considered. The calculations were performed by means of in-house CFD code SigmaFlow. The numerical simulation for part load, high load and best efficiency operation points were performed.

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Section: Mathematical Model and Numerical Methodsmentioning

confidence: 99%

Section: Mathematical Model and Numerical Methodsmentioning

confidence: 99%

Steady state operation simulation of the Francis-99 turbine by means of advanced turbulence models

Gavrilov

Дектерев

Минаков

et al. 2017

J. Phys.: Conf. Ser.

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“…The stability of turbine operation is directly related to the safety of power station (Gavrilov et al 2016;Romero-Gomez et al 2017). The vibration generated during the operation of the unit mainly comes from two reasons: mechanical vibration caused by manufacturing and installation errors and hydraulic vibration caused by unstable internal flow of the unit.…”

Section: Introductionmentioning

confidence: 99%

Effect of Guide Vane Pitch Circle Diameter on Pressure Fluctuation in Vaneless Zone of Francis Turbine

2020

JAFM

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In a Francis turbine, the guide vanes are arranged in the direction of flow behind the stay vanes. And as it is generally believed that the outlet angle of water after it flows through the spiral case and stay vanes is fixed, the flow and flow circulation are altered by changing the opening of the guide vanes so as to change the output of the turbine. The rotor-stator interaction effect induced by the interaction between the guide vanes and the runner of the Francis turbine was one of the main causes of the pressure fluctuation. The effect of guide vanes placement on pressure fluctuation in vaneless zone of Francis turbine was studied. In this study, the commercial software ANSYS CFX16.0 was used for the three-dimensional numerical simulation of the whole flow passage of a Francis turbine model in a power station. The turbulence model used in the calculation was the shear stress transport (SST) model. The independence between the total number of computational meshes and the timestep was verified to ensure the reliability of the calculation results. Five schemes with different diameters of the guide vanes distribution circle were proposed including D0/D1 (guide vane pitch circle diameter /diameter of runner inlet) equaling to 1.119, 1.128, 1.138, 1.144, and 1.15. The steady calculation results showed that, when the turbine was operating under the design condition, D0/D1 increased from 1.119 to 1.15, and the turbine efficiency and output showed a monotonically increasing trend, with the efficiency increased by 0.17 percentage point and output increased by 3.91kw. Twenty monitoring points were set up in the vaneless zone between the guide vanes and the runner to collect pressure fluctuation signals in the vaneless zone. By analyzing the characteristics of unsteady pressure fluctuations in the vaneless zone under design conditions of the five schemes, the optimal position of the guide vanes was determined. The numerical results showed that the pressure fluctuation amplitude at monitoring points in the same axial direction increased gradually from the top cover to the bottom ring. When the unit operated under the design conditions, by increasing the guide vane pitch circle diameter, the rotor-stator interaction between the guide vanes and the runner domain was weakened, and the pressure fluctuation amplitude in the vaneless zone between the guide vanes and the runner was reduced, thereby the stability of unit operation was improved.

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“…The researchers attempted to analysis the pressure fluctuations in the rotating part and the non-rotating part. These studies are helpful for a deeper understanding of the pressure oscillations mechanisms in a Francis turbine with splitter blades [10][11][12]. However, more work is needed to further demonstrate the cavitating rope on the Francis-99 draft tube core and the improvement of cavitating characteristics in the runner with splitter blades.…”

Section: Introductionmentioning

confidence: 99%

Simulation and Analysis of Cavitating Flow in the Draft Tube of the Francis Turbine with Splitter Blades at Off-Design Condition

Tran

Long

2019

Teh. vjesn.

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Hydraulic plants are required to operate with wider operating range to cover the variants of power outputs into the electrical grid. Although there have been many studies of off-design conditions, studies of cavitating draft tube vortices at the Francis turbine with splitter blades are limited, and the cavitating property is not yet well comprehended. This study presents a prediction of the cavitating characteristics in the Francis-99 draft tube obtained by numerical analysis using the Zwart mass transfer model and shear-stress transport (SST) model. The shape characteristics of two types of cavitating vortex rope (spiral and columnar) and its influence on the cavitation development in the runner blades are analyzed. The link between cavitation with the vorticity is further highlighted by the vorticity transport equation (VTE). The result indicates that the runner cavitating is symmetric for both types of cavitating vortex ropes, and cavitation is significantly improved when a runner with splitter blade is used.

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Vortical structures and pressure pulsations in draft tube of a Francis-99 turbine at part load: RANS and hybrid RANS/LES analysis

Cited by 32 publications

References 16 publications

Steady state operation simulation of the Francis-99 turbine by means of advanced turbulence models

Steady state operation simulation of the Francis-99 turbine by means of advanced turbulence models

Effect of Guide Vane Pitch Circle Diameter on Pressure Fluctuation in Vaneless Zone of Francis Turbine

Simulation and Analysis of Cavitating Flow in the Draft Tube of the Francis Turbine with Splitter Blades at Off-Design Condition

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