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TECHNICAL PAPERS

Bubble-Induced Unsteadiness on A Wind Turbine Airfoil

[+] Author and Article Information
E. A. Mayda, C. P. van Dam

Department of Mechanical and Aeronautical Engineering, University of California, Davis, Davis, CA 95616

J. Sol. Energy Eng 124(4), 335-344 (Nov 08, 2002) (10 pages) doi:10.1115/1.1510525 History: Received March 01, 2002; Revised July 01, 2002; Online November 08, 2002
Copyright © 2002 by ASME
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References

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Figures

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Lift curves of NACA 641-012 for a range of Reynolds numbers, free transition 2
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Time-averaged laminar separation bubble 7
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Simplified model of bubble effect on surface pressure distribution 8. S=separation,T=transition,R=reattachment
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Streamlines for steady separated flow over flat plate 11
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Instantaneous streamlines for unsteady separated flow over flat plate (F=2.0×10−4)11
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Leading- and trailing edge locations of separation bubble for steady (---) and unsteady (–) conditions; F=1.25×10−4 (x),F=1.4×10−4 (o),F=2.0×10−4 (▵) 11
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C-type grid around S809 airfoil
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Close-up of grid around S809
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Close-up of grid in S809 leading-edge region
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Comparison of computed steady surface pressures on baseline, intermediate and fine grids at α=4°,Re=1.0×106,M=0.2, and transition fixed at xu/c=0.407,xl/c=0.383.
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Comparison of computed unsteady and mean surface pressures (baseline grid, fully laminar) and measured surface pressures 27, α=4°,Re=1.0×106,M=0.2
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Comparison of computed unsteady and mean surface pressures (intermediate grid, fully laminar) and measured surface pressures 27, α=4°,Re=1.0×106,M=0.2
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Comparison of computed unsteady and mean surface pressures (fine grid, fully laminar) and measured surface pressures 27, α=4°,Re=1.0×106,M=0.2
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Comparison of computed unsteady and mean surface pressures (baseline grid, transition @xu/c=0.557,xl/c=0.533), and measured surface pressures 27, α=4°,Re=1.0×106,M=0.2
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Comparison of computed unsteady and mean surface pressures (intermediate grid, transition @xu/c=0.557,xl/c=0.533) and measured surface pressures 27, α=4°,Re=1.0×106,M=0.2
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Instantaneous streamlines for unsteady separated flow over S809 airfoil (intermediate grid, α=4°,Re=1.0×106,M=0.2, transition @xu/c=0.557,xl/c=0.533)
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Comparison of computed unsteady and mean surface pressures (fine grid, transition @xu/c=0.557,xl/c=0.533) and measured surface pressures 27, α=4°,Re=1.0×106,M=0.2
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Instantaneous pressure contours depicting bubble-induced vortex shedding (fine grid, transition @xu/c=0.557,xl/c=0.533),α=4°,Re=1.0×106,M=0.2
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Comparison of computed unsteady and mean surface pressures (intermediate grid, transition @xu/c=0.557,xl/c=0.533, Baldwin-Barth model) and measured pressures 27, α=4°,Re=1.0×106,M=0.2
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Computed lift and drag (baseline grid, transition @xu/c=0.557,xl/c=0.533),α=4°,Re=1.0×106,M=0.2
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Mesh size dependence of global (lift) and local (unsteady bubble pressure) oscillatory frequencies. Cell length is defined as the square root of the average cell area for each mesh.

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