Turbine Blades

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Turbine Blades

• Terry Andersen
• Nathan Stastny
• ME 372
• Brigham Young University
• Fall 2001

2
Overview

• Applications
• Design Considerations
• Material Considerations
• Manufacturing Processes
• Review
• Questions

3
Applications

• Gas Turbine Generators
• Jet Engines

4
Rolls Royce
Turbine Blades
Rolls Royce Trent
5
Design Considerations

• Geometry
• Cooling Vanes
• Attachment Interface
• Safety Factors

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Geometry

• Strength / Fatigue Life
• Each row will be different
• Air Flow (CFD Package)
• Machineability

General Turbine Blade Shape
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Cooling Vanes

• Blades must be kept cool
• Often operate near the metal melting point
• An increase of only 17 ?C can decrease the engine
  life by half
• Cool (300 ?C ) air is run out of the blades
  through small holes (vanes), keeping the blades
  from melting.

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Pic
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Attachment

• Keep Stress Concentrations Low
• Fir Tree Attachment
• Reduced stress
• concentrations
• Easy replacement
• Also known as the
• Christmas Tree

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Safety Factors

• Higher S.F. is usually the best.
• But what if the engine runs out of control at
  speeds higher than intended?
• The energy of the rotating blades goes up with ?2
• What happens if the blades brake at 10 overload?
  20, 30, 40, 50 ?
• Too much energy and the blades might break
  through the engine shroud and into the fuselage.

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Quick VideoBoeing 777Engine Test
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Material Considerations

• Environment
• Creep
• Current Materials Used
• Materials In Research

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Environment

• Air Temperature Between 850 and 1600 C
• Melting Temperature
• Steel1400?C
• Nickel Alloy 1200?C
• Titanium1650?C
• Turbine RPM Appx. 20,000 rpm

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Creep

• Turbine blades elongate during their life
• Tip clearance
• Result of environment and grain structure
• Soft abradable lining
• Directional solidification (cooling)
• Single crystal structure

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Current Materials Used

• Initially Steel
• Nickel Alloys
• Most common material is Titanium
• Laser peening
• Ceramic Coatings

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Material In Research

• Ceramic blades
• Carbon composite blades
• Noise reduction
• Light weight

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Manufacturing Processes

• Machining (not too common)
• Investment Casting
• Secondary machining
• Electro-Chemical Machining
• Single operation

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Design Sites

• www.pccsmp.com (manufacturing)
• www.turboblades.com (manufacturing)
• www.giverin.demon.co.uk/NewFiles/HTWTurbines.html
  (information)
• www.gas-turbines.com/begin (information)
• www.pratt-whitney.com (engine manufacturer)

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Review

• Applications
• Jet Engines
• Gas Turbine Generators
• Design Factors
• Geometry
• S.F.
• Materials
• Very high temperatures
• Titanium
• Manufacturing

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Questions
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Dr. Chase Squadron Commander
Nathan
Terry
Special thanks to all those who didnt believe in
us, but whom weve proved wrong.