Biomimetic Nano-Surface Creation

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Biomimetic Nano-Surface Creation for Drag
Reduction in Fluid Power Systems
Stephen M. Moran August 9th, 2007
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THE CONCEPT

• Lotus leaves exhibit super-hydrophobicity due to
  their nano-scale surface geometry combined with
  an exterior chemistry with low surface energy

• Flow resistance decreases because of air-water
  interface
• Apply concept to fluid transmission lines in
  fluid power systems

Water droplets bead
CCEFP UROPCS S. Moran
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PREVIOUS STUDIES
50 nm
300 nm
2 µm
100 nm
2 µm
(P. Joseph et al, 2006)
(T. Lin et al, 2005)

• (J. Kim et al, 2002)
• Surface
• Nano-turf using silicon etching
• Experiment
• Water droplets and channel flow

• (A. Balasubramanian et al, 2003)
• Chemically treated foil

(C. Henoch, 2006)

• Nano-particle spray coatings

• Nano-grass using silicon etching

• Carbon nano-tube forest

• Water pipe flow

• Free surface water flow

• Water channel flow

• Water droplets

theory ? smooth surface 30 µm microposts
of spacing ? 15 µm 30 µm ? 60 µm
? 150 µm

• 10-50 pressure drop reduction with water
  achieved
• No oil flows and very few pipe flows
• No high pressure systems or flexible surfaces

CCEFP UROPCS S. Moran
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THE APPROACH

• First, research nano-coating effectiveness in
  increasing contact angle and decreasing sliding
  angle of liquid droplets

50 nm

• Concurrently, determine optimal surface geometry
  using photolithography to fully control surface
  shape and scale
• Currently impractical construction method for
  fluid lines
• Modified nano-molding method may be possible

• Finally, apply working surfaces to flow setup and
  investigate effectiveness in reducing friction
  loss in fluid transmission lines by comparing
  pressure drop measurements of lines with and
  without nano-texturing

CCEFP UROPCS S. Moran
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EXPERIMENTAL SETUP

• Setup for droplet experiments
• Goniometer contact angle
  measurement
• Droplet sliding angle measurement

CCEFP UROPCS S. Moran
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EXPERIMENTAL SETUP

• Initial Experiments with Droplets
• Control LEXAN plate cleaned of particles
• Textured 6 weight of TiO2 nanoparticles
• 8 weight of Zonyl 8740
• 86 weight of distilled water
• spray coated from 30 cm distance
• 2 coats
• Liquid 1 distilled water
• Liquid 2 Mobil DTE 11M hydraulic oil
• Liquid 3 Mobil DTE 18M hydraulic oil
• (viscosity approx 10x greater than 11M)
• Measure contact angle vs. droplet size

CCEFP UROPCS S. Moran
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RESULTS

• CONTACT ANGLE RESULTS
• 8.0 µL water droplet and 3.4 µL oil droplet (Bond
  numbers of water and oil droplet made equivalent)
• Oil-water contact angles not equal ? liquid-solid
  surface tension effects must be taken into account

CCEFP UROPCS S. Moran
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RESULTS

• CONTROL SURFACE

CCEFP UROPCS S. Moran
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RESULTS

• CONTROL SURFACE

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RESULTS

• TEXTURED SURFACE

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RESULTS

• TEXTURED SURFACE

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RESULTS

• SLIDING ANGLE RESULTS

CCEFP UROPCS S. Moran
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RESULTS

• SLIDING ANGLE RESULTS

CCEFP UROPCS S. Moran
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ONGOING WORK

• Setup for flow experiments

Peristaltic Pump
Pulse Dampener
Test Section
Hydraulic Oil
?p
Differential Pressure Transmitter
CCEFP UROPCS S. Moran
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ONGOING WORK

• Flow Setup Scaling
• Verify that flow parameters scale properly for
  smooth pipe
• Viscosity
• Length
• Cross-sectional area
• Flow rate
• More Surface Work
• Apply effective nano-surfaces to flow setup and
  investigate pressure drop reduction
• Investigate and apply various fluorinated polymer
  films and Self-Assembling Monolayer (SAM)
  coatings to lower surface energy
• Repel oil droplet staining because at first,
  sliding oil droplets left a trailing stain on
  nano-textured surfaces

CCEFP UROPCS S. Moran
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THANK YOU

• Thank you NASA ISGC, The Boeing Company, NSF,
  CCEFP for their financial support.

• Special thanks to Dr. Eric Loth and graduate
  student Adam Steele.

CCEFP UROPCS S. Moran
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QUESTIONS
CCEFP UROPCS S. Moran