Some Interfacial Thermodynamics Issues Involved In Water Erosion Project

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• Some Interfacial Thermodynamics Issues Involved
  In Water Erosion Project
• A Presentation For MECH 6661 Course
• Wei (Alex) Chen
• Supervisor Dr. M.
  Medraj
• 05/12/2011

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OUTLINE
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Wetting Angles
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Surface Energy
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Simplifications
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Hydrophobicity For water
Teflon
Ceramic
? 18 dyne/cm
Water ? 73 dyne/cm
Metal
Glass
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Fundamentals Surface Area
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Lotus Effect Bio-mimic Material
Photo Source http//en.wikipedia.org/wiki/FileLo
tus3.jpg.
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Lotus Effect Bio-mimic Material
Lotus Effect
Photo Resource http//www.thenakedscientists.com/
HTML/uploads/tx_naksciimages/lotus_leaf_jpg.jpg
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Ref Shirtcliffe, 2010
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Printing or Etching ? Hydrophobic, even metal
surfaces
Ref Shirtcliffe, 2010
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Turbine Inlet Cooling-- Why there is water?
Stationary Blades
Rotating Blades
Gas Turbine Compressor
Photo Source http//www.wikipedia.org/turbojet
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Droplet Erosion Issues --- droplet size
Secondary Droplets
Air
Compressor
Typical size 5-10 µm (gt50 µm,
cooling effectiveness ?)
Rotating blades
Data Source Khan. 2009.
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Why Why Not?
Why Hydrophobic?
Why Not?
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Dominant Factor Dynamic Load, Momentum
Static Load
Photo Source http//images.google.com
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Dominant Factor Dynamic Load, Momentum
Dynamic Load
Momentum Overwhelms Surface Tension
Photo Source http//images.google.com
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Turbine Inlet Cooling-- Why there is water?
Stationary Blades
Rotating Blades
Impact Speed Up to 500 m/s
Gas Turbine Compressor
Photo Source http//www.wikipedia.org/turbojet
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Non-equilibrium State _at_ Laser Cladding
Dilution ? Laser Power h/b ? 1/ power
Ref Toyserkani, 2005
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Non-equilibrium State _at_ Laser Cladding
Spreading Factor
Laser Power ?
Photo Source Toyserkani, 2005
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Effect of oxidation
Spreading Factor
Oxidation

• Grinding
• (Deoiling)

• Inert gas
• Reduce laser power ?

Data Source Bondi, 1952
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Thank you!