Performance of Biologically Inspired Flapping Foils

1
Performance of Biologically Inspired Flapping
Foils

• Melissa Read
• January 31, 2007

2
Motivation
Goal Determine relevant design parameters for
operation of UAVs at low and variable Reynolds
numbers.
3
Achieving Maximum Thrust Three Zone Theory
Images from Anderson
4
Hypothesis and Research Plan

• Hypothesis Peak Thrust Strouhal Number and
  Boundaries of Three Zones are a
  function of Reynolds Numbers
• Research completed
• 1) Confirm Three Zones exist at low Reynolds
  number cases
• 2) Identify Boundaries of Three Zones for
  multiple Reynolds Numbers
• 3) Determine Peak Thrust Strouhal Number as a
  function of Reynolds number

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Section 1Confirm Three Zones for Low Re

• 1a) Identify wake structures in previous
  literature
• Discovered competing theories
• 1b) Design of Fluorescent Dye Visualizations to
  determine wake structure
• 1c) Execution of Fluorescent Dye Visualizations
• Discussion of Results with regard to Three
  Zones
• Aside Comparison to each of the two competing
  theories identified in previous literature

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Confirm Three Zones for low Re Previous
Literature

• Two opposing theories
• 1)Von Ellenrieder (right top, right bottom)
• -Fluorescent Dye Visualization
• -Shows secondary
• filamentary arms
• -Does not agree with Three
• Zones
• 2) Blondeaux (bottom)
• -CFD experiment
• -Shows agreement with Three Zones

von Ellenrieder
von Ellenrieder
Blondeaux
Blondeaux
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Confirm Three Zones for low Re Fluorescent
Dye Visualization

• Experiment Design
• NACA 0030 foil
• c19mm
• h08.5mm
• s57mm
• Re161.5
• St0.2 - 0.4
• ?00 - 20
• F60 - 120
• h(t)h0sin(2pft)
• ?(t)?0sin(2pft F)

8
Confirm Three Zones for low Re Pitching and
Heaving Mechanism

• 80/20 Al Frame
• 600 mm tank (Breeder 40)
• Forward Motion Lead Screw
• Pitching and Heaving Scotch-Yoke Mechanism

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Confirm Three Zones for low Re Pitching and
Heaving Mechanism
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Confirm Three Zones for low Re Dye
Application
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Confirm Three Zones for low Re Experimental
Setup
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Confirm Three Zones for low Re Dye
Visualization Data
Planform
Wingtip
Isometric
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Confirm Three Zones for low Re Dye
Visualization Results
?
St0.2
St0.4
Re161.5
14
Confirm Three Zones for low Re Comparison to
CFD, Wingtip

Top Dye Visualizations Bottom Blondeaux CFD
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Confirm Three Zones for low Re Comparison to
CFD, Planform
Top Dye Visualizations Bottom Blondeaux CFD
16
Confirm Three Zones for low Re Comparison to
CFD, Isometric

Top Dye Visualizations Bottom Blondeaux CFD
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Confirm Three Zones for low ReResults of Dye
Visualizations

• Confirmation of zones 1 and 2
• Dye unable to operate in Zone 3
• Data confirmed by Blondeaux CFD
• Questions raised about the effect of the dye
• PIV needed to further verify results

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Section 2Identifying Boundaries of Three Zones

• 2a) Discussion of Particle Image Velocimetry
• 2b) Verification of Fluorescent Dye Visualization
  results
• 2c) Qualitative Results of PIV Three Zones
  Boundary Locations

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Identify Boundaries of Three Zones Particle
Image Velocimetry
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Identify Boundaries of Three Zones Particle
Image Velocimetry
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Identify Boundaries of Three Zones Comparison
to Blondeaux
Top PIV results Bottom Blondeaux CFD
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Identify Boundaries of Three Zones Results
Re161.5
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Identify Boundaries of Three Zones Results
Re750
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Identify Boundaries of Three Zones Results
Re1000
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Identify Boundaries of Three Zones Results
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Section 3Determine StPT as a function of Re

• 3a) Calculating thrust using a control volume
  method
• 3b) Results
• 3c) Discussion of how these results fit in with
  prior results and trends

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Determine StPT as a function of ReControl
Volume Method
U
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Determine StPT as a function of ReExperimental
Results
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Determine StPT as a function of ReExperimental
Data
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Determine StPT as a function of ReExperimental
DataAnderson Data
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Determine StPT as a function of ReExperimental
DataFish Data
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Determine StPT as a function of ReTrends
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Conclusions

• Three Zones Exist for Re 102105
• Boundaries of Three Zones Shift to lower
  Strouhal Numbers as Reynolds Number increases
• Peak Thrust Strouhal number decreases as Reynolds
  number increases
• More data needed to determine exact relationship
  between Peak Thrust Strouhal number and Reynolds
  number

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Acknowledgements

• Professor Alexandra Techet
• Cha Ling OConnell, Matthew Krueger, David Tobias
• Experimental Hydrodynamics Group, including Tadd
  Truscott, Brendan Epps, and Matthew Weldon

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Experimental Parameters
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Fish Tail Motion
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Velocity Profiles Re161.5
St0.2 St1.1
St1.5
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Velocity Profiles Re750
St0.2 St0.5
St1.1
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Velocity Profiles Re1000
St0.2 St0.5
St0.8
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Dye Selection

Freymouth, 1989
Read, 2006
Von Ellenrieder, 2003
Read, 2006
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Flapping Foil Mechanism
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Dye Visualization Experiment Considerations

• Smooth Mechanism
• Separate heave and pitch motors (Von Ellenrieder)
• Scotch Yoke Style Mechanism (Anderson)
• Achieving Constant Forward Velocity
• Tow Tank (Anderson)
• Water Tunnel (Von Ellenrieder)
• Clear, non interfering visualization medium
• Coating (Freymouth)
• Injection (von Ellenrieder)

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Determining Wake Dynamics at Low Reynolds Numbers

• Fluorescent Dye Visualization
• Shows 3D wake structure in one experiment
• Potentially alters flow by introducing a
  different fluid into the boundary layer of the
  foil
• Particle Image Velocimetry
• Non Interfering vorticity measurement
• Detriments 2D (3D equipment not available)

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Parameters Used to Vary Ct with Respect to St
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Parameter Definitions
U
ho
?o
c