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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
Unsteady Rotor-Stator Simulation of the U9 Kaplan Turbine Model
Olivier Petit, Håkan Nilsson Chalmers University
6th OpenFOAM workshop
Penn State University, USA
13-16 June 2011
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• Develop OpenFOAM as the future first choice for industrial CFD in water turbine applications ( validate new implementations useful for Turbomachinery applications)
• Interact with the experimental project, in order to improve the flow in the U9 model
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• Prototype located in Porjus, consist in a Kaplan turbine.
• Designed to be able to perform detailed measurements on a real scale turbine/generator unit.
• 1:3.1 scale model of the U9 turbine is set up at Vattenfall Research and Development in Älvkarleby.
U9 unit, Porjus, Sweden
U9 scale model, Älvkarleby, Sweden
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• Create a detailed measurements database that can be used to validate future numerical simulations.
• Investigate the impact on the flow of the curved pipe at the inlet of the spiral casing.
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• U9 spiral casing: mesh of 5 millions cell, block structured hexaedral, realized with ICEM-HEXA.
• Y+ value between 50-100.
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• U9 Runner: mesh of 100 000 cell, block structured hexaedral, realized with ICEM-HEXA.
• Y+ value between 50-100.
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• U9 draft tube: mesh of 1 million cell, block structured hexaedral, realized with ICEM-HEXA.
• Y+ value between 50-100.
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
A
A
A-A
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• At the inlet of the spiral casing, velocity profiles measured with LDA technique at 5 horizontal profiles(Py 1-5), and 1 vertical (Pz). • Results presented in dimesionless form using Rinlet=0.316m, and vBulk=Q/Ainlet , Q=0.71 m.s-1
• Comparison between experimental and numerical results are shown for the best efficiency point, Q=0.71 m/s, and alpha=26° (angle of the guide vanes)
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
![Page 11: Unsteady Rotor-Stator Simulation of the U9 Kaplan …...Unsteady Rotor-Stator Simulation of the U9 Kaplan Turbine Model Olivier Petit, Håkan Nilsson Chalmers University 6th OpenFOAM](https://reader036.vdocuments.site/reader036/viewer/2022062506/5f0bc5627e708231d432224a/html5/thumbnails/11.jpg)
Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• Similar behaviour between experimental and numerical results.
• Difference between numerical and experimental prediction of the flow can be due to the turbulence model: the k-ε model is not accurate enough to give a good prediction of the flow in a curved pipe.
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• Reference point is at the wall for both windows.
SI SII
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
Inlet boundary conditions
• The reference point is located on the centreline. • Axi-symmetric profile is taken at the inlet from experimental data provided by Berhanu Mulu
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
P1_a P1_c
P3_a P3_c
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• Inlet boundary condition needs to include the unsteadiness of the wakes to predict accurately the flow in the draft tube • Radial velocity must be included to get a good approximation of the flow • Better turbulence model should predict more accurately the flow features.
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• mesh of 12 million cell, block structured hexaedral, realized with ICEM-HEXA.
• 7 GGI interfaces, linking different part of the U9 model
• TransientSimpleDyMFoam, OpenFOAM-1.5-dev, k-ε model
• Inlet boundary condition: plug flow with Q=0.71 m/s
• Turbulence parameters calculated so that I=0.1, and νT/ν=10.
• CFD tool is OpenFOAM. Pressure and velocity probes are created to monitor the flow in the spiral casing and in the draft tube.
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• The prediction of the flow before the runner is rather accurate
• A separation of the flow occurs after the runner blades, pushing the flow against the shroud . The y-plus value needs to be lowered in the runner area.
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Chalmers University of Technology
Svensk Vattenkraft Centrum - SVC
• Focus on the U9 runner to get proper y+ value, and proper flow behaviour
• Pressure, velocity analysis of the whole U9 model and comparison with the measurement data.
Thank you for your attention!