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CFD Simulation: MEXICO Rotor Wake

CFD Simulation: MEXICO Rotor Wake. EWEC: 2009 Andreas Bechmann & Niels Sørensen Risø DTU ∙ National Laboratory for Sustainable Energy andh@risoe.dtu.dk. Outline:. Background MEXICO Experiment CFD Simulations Conclusion. Background 1/3.

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CFD Simulation: MEXICO Rotor Wake

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  1. CFD Simulation: MEXICO Rotor Wake EWEC: 2009 Andreas Bechmann & Niels Sørensen Risø DTU ∙ National Laboratory for Sustainable Energy andh@risoe.dtu.dk

  2. Outline: • Background • MEXICO Experiment • CFD Simulations • Conclusion CFD Simulation of the MEXICO Rotor Wake

  3. Background 1/3 “Today, siting of wind turbines in wind farms is based on power output considerations” TOPFARM project: Optimization of wind farm topology based on power output and turbine loads. WP1: Internal flow model Model to describe the flow inside the wind farm CFD Simulation of the MEXICO Rotor Wake

  4. Background 2/3 How to validate the model? Wind farm Single wind turbine Wind tunnel CFD Simulation of the MEXICO Rotor Wake

  5. Background 3/3 • The MEXICO Experiment • Controlled conditions • PIV measure. 1.3D downstream • Open wind tunnel – tunnel effects? Objectives: To make a “clean” dataset for validating wake models Method: Extract wake data from the MEXICO experiment Compare measurements with high resolution CFD Combine measurements and CFD results in a dataset for validating wake models Wind tunnel CFD Simulation of the MEXICO Rotor Wake

  6. Outline: • Background • MEXICO Experiment • CFD Simulations • Conclusion Title of the presentation

  7. MEXICO Exp. 1/4 MEXICO Info: (pictures by ECN, NLR) Model Experiments in Controlled Conditions Purpose: ”measurements on wind turbine model including the near wake” Large tunnel of DNW used Many groups participated: ECN was coordinator The Vindtunnel: Open section 9.5×9.5m Max. air speed 30 m/s Balance (3 forces/moments) CFD Simulation of the MEXICO Rotor Wake

  8. MEXICO Exp. 2/4 The Rotor: 4.5m diameter 3 airfoils for each blade: 1. Root: DU 91-W2-250 2. Mid: RISØ A1-21 3. Tip: NACA 63-418 Zig-zag tape at 5% chord Pitch angle -2.3 degrees No signal from strain gages? (global rotor forces are estimated from the balance) Pressure at 5 sections (25%,35%,60%,82%,95%) CFD Simulation of the MEXICO Rotor Wake

  9. MEXICO Exp. 3/4 Earlier CFD findings • 1/10 scale of DNW wind tunnel • Clear tunnel effects in the far wake • Tunnel effects limited at the rotor Niels N. Sørensen, Risø/DTU MEXICO, 3. Progress Meeting, Athens 28-29 Nov. 2001 Doeke Rozendal Flow field measurements on a small scale wind turbine model in the DNW PLST wind tunnel NLR-CR-2003-485 The PIV measurements: • PIV measuring sheet (34×40cm) placed horizontally at 270 deg azimuth • In phase with rotor (freq=3 rotor revolutions) for 40s (100 samples) • Axial traverse at r/R=0.82 • Radial traverses from r/R=0.5-0.9 -0.6D -0.4D 0.3D 1.0D -1.0D 1.3D CFD Simulation of the MEXICO Rotor Wake

  10. MEXICO Exp. 4/4 Selected data: 100 GB of data Axi-symmetric cond. No yaw Pitch angle -2.3 degree 425 rpm (tip speed 100m/s) Wind speed: 10, 15, 24 m/s (tip speed ratio 10, 6.7, 4.2) CFD Simulation of the MEXICO Rotor Wake

  11. Outline: • Background • MEXICO Experiment • CFD Simulations • Conclusion CFD Simulation of the MEXICO Rotor Wake

  12. The Simulations 1/5 CFD solver: EllipSys3D RANS: SST k-ω model Fully turbulent Steady-state simulations Surface mesh: All 3 blades meshed 256×64 cells on each Volume mesh: 256 cells in normal direction (~7 rotor diameters) Wake resolved approx 3D Wind tunnel is not included CFD Simulation of the MEXICO Rotor Wake

  13. The Simulations 2/5 Rotor forces: Thrust. Estimated tower drag subtracted from balance force Pressure distributions. CFD Simulation of the MEXICO Rotor Wake

  14. The Simulations 3/5 CFD Simulation of the MEXICO Rotor Wake

  15. The Simulations 4/5 Wake results: -0.6D -0.4D 0.3D 1.0D -1.0D 1.3D CFD Simulation of the MEXICO Rotor Wake

  16. The Simulations 5/5 Validation dataset : Tunnel effects removed Expands further downstream Airfoil characteristics has been extracted which includes 3D effects CFD Simulation of the MEXICO Rotor Wake

  17. Outline: • Background • MEXICO Experiment • CFD Simulations • Conclusions CFD Simulation of the MEXICO Rotor Wake

  18. Conclusions • Wake data extracted from MEXICO database • CFD simulations of MEXICO wake were performed • Measurements and simulations compare well • Only the near-wake was simulated (~3D) (due to mesh topology) • Simulations with laminar–turbulent transition could be interesting • A new validation dataset for wake models without tunnel effects Thank you for listening! CFD Simulation of the MEXICO Rotor Wake

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