Flow Simulation of a Maple Seed

Jake HoldenThomas CaleyDr. Mark Turner

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Goals & Objectives• Question to answer: “How has time

optimized this natural wind turbine?”• Understand/discover the physical and

rotational properties of the maple seed• Simulate the flow field of a falling maple

seed • Post-process the results to analyze and

understand the flow field• Modify standard conditions and design to

explore wind turbine potentials

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Timeline

Task 1 2 3 4 5 6 7 8 9 10

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Understand goals and review literature

Quantify seed specimens

Learn CFD tools

Simple ducted flow simulations

Full falling seed simulation

Solution analysis and concept testing

Final takeaways and deliverables

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Accomplishments• Collected Seed samples (12)• CT Scans of seeds to acquire 3D model• Recorded falling maple seeds with high-

speed camera at 3000 frames/second• Quantified high-speed data (rotation

speed, angle of rotation, and fluid velocity)• Computational Fluid Dynamics (CFD)

simulation of seed falling in duct to analyze work done by seed

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1. Seeds were placed in foam fixture on their back edge to prevent blade distortion and allow multiple parts per scan.2. Fixture was placed in machine on turntable

CT Scans

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3D Geometry

*All geometry thanks to Exact Metrology donating time and expertise

CT scanning time takes about 1.5 hours, then final model must be constructed in proprietary software

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High-Speed Data (1 of 2)

Species 1 Species 2 Species 3

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High-Speed Data (2 of 2)

Species 1 Species 2 Species 3

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Flow Physics

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Computational Fluid DynamicsWorkflowGeometry (CT

Scans)

Grid Fluid Volume

Establish Models & Assumptions

Run CFD Solver

Post Process Solution

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Assumptions/Model

• Pressure outlet wall and rotating seed body

• Incompressible Flow • Steady Flow• Three-Dimensional• Turbulence Modeling (k-ε)• No structural deflection (rigid body)

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CFD Simulation (1 of 8)

Cylindrical Domain Grid Generation≈ 2 million pts

CFD Simulation (2 of 8)

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Relative Velocity Stream tubes extended in both directions to show fluid as seen by the seed

CFD Simulation (3 of 8)

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Relative Velocity Stream tubes on Pressure (bottom) and Suction (top) sides

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CFD Simulation (4 of 8)

Relative Velocity Stream tubes on Pressure (bottom) and Suction (top) sides

CFD Simulation (5 of 8)

Relative Velocity Stream tubes at Leading Edge

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CFD Simulation (6 of 8)

Relative Velocity Stream tubes looking from tip to seed illustrating Leading Edge incidences

Seed Static Pressure Contours

CFD Simulation (7 of 8)

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Suction Side (Top)

Pressure Side (Bottom)

CFD Simulation (8 of 8)

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InletOutlet

Relative Total Pressure contours on the inlet and outlet of the duct (*notice the average drop in Pt)

Performance Analysis (1 of 2)

• Figures of Merit:– Axial Induction Factor– Lift vs. Weight

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Performance Analysis (2 of 2)

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Next Steps• Balance Lift & Weight by tweaking

flow velocity and rotational velocity• Modify geometry to observe how

specific features impact flow characteristics

• Draw comparisons and continue analyzing in terms of wind turbine performance

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References• Sairam, K. (2013) “The influence of Radial Area Variation on Wind

Turbines to the Axial Induction Factor”, M.S. Thesis, University of Cincinnati, Cincinnati, Ohio

• Normberg, R. A. “Auto-Rotation, Self-Stability, and Structure of Single-winged Fruits and Seeds (Samaras) with Comparative Remarks on Animal Flight” Biology Review 48 (1973), 561-96. Print.

• www.exactmetrology.com/ *Special Acknowledgement to Exact Metrology for scanning images

• http://www.compadre.org/informal/features/featureSummary.cfm?FID=1227

• http://preachrr.wordpress.com/2011/04/07/maple-seed-design-really-%E2%80%9Ctakes-off%E2%80%9D/

• http://apps.carleton.edu/campus/facilities/sustainability/wind_turbine/