Flow Simulation of a Maple Seed Jake Holden Thomas Caley Dr. Mark Turner

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

Timeline Task 1 2 3 4 5 6 7 8 9 10 11 12 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

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

CT Scans 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

3D Geometry CT scanning time takes about 1.5 hours, then final model must be constructed in proprietary software *All geometry thanks to Exact Metrology donating time and expertise

High-Speed Data (1 of 2) Species 1 Species 2 Species 3

High-Speed Data (2 of 2) Species 1 Species 2 Species 3

Flow Physics

Computational Fluid Dynamics Workflow Geometry (CT Scans) Grid Fluid Volume Establish Models & Assumptions Run CFD Solver Post Process Solution

Assumptions/Model Pressure outlet wall and rotating seed body Incompressible Flow Steady Flow Three-Dimensional Turbulence Modeling (k-ε) No structural deflection (rigid body)

CFD Simulation (1 of 8) Cylindrical Domain Grid Generation ≈ 2 million pts

CFD Simulation (2 of 8) Relative Velocity Stream tubes extended in both directions to show fluid as seen by the seed

CFD Simulation (3 of 8) Relative Velocity Stream tubes on Pressure (bottom) and Suction (top) sides

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

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) Suction Side (Top) Pressure Side (Bottom) Seed Static Pressure Contours

CFD Simulation (8 of 8) Outlet Inlet 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

Performance Analysis (2 of 2)

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

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/