1. 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 Rolls Royce Trent Turbine Blades

5. Design Considerations Geometry Cooling Vanes Attachment Interface Safety Factors

6. Geometry Strength / Fatigue Life Each row will be different Air Flow (CFD Package) Machineability General Turbine Blade Shape

7. 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.

8. Pic

9. Attachment Keep Stress Concentrations Low “Fir Tree” Attachment –Reduced stress concentrations –Easy replacement –Also known as the “Christmas Tree”

10. 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 ω 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.

11. Quick Video Boeing 777 Engine Test

12. Material Considerations Environment Creep Current Materials Used Materials In Research

13. Environment Air Temperature: Between 850 and 1600 °C Melting Temperature: –Steel:1400  C –Nickel Alloy: 1200  C –Titanium:1650  C Turbine RPM: Appx. 20,000 rpm

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

15. Current Materials Used Initially Steel Nickel Alloys Most common material is Titanium Laser peening Ceramic Coatings

16. Material In Research Ceramic blades Carbon composite blades –Noise reduction –Light weight

17. Manufacturing Processes Machining (not too common) Investment Casting –Secondary machining Electro-Chemical Machining –Single operation

18. Design Sites 1.www.pccsmp.com (manufacturing) 2.www.turboblades.com (manufacturing) 3.www.giverin.demon.co.uk/NewFiles/HT WTurbines.html (information) 4.www.gas-turbines.com/begin (information) 5.www.pratt-whitney.com (engine manufacturer)

19. Review Applications: –Jet Engines –Gas Turbine Generators Design Factors: –Geometry –S.F. Materials: –Very high temperatures –Titanium Manufacturing:

20. Questions

21. Terry Nathan Dr. Chase Squadron Commander Special thanks to all those who didn’t believe in us, but whom we’ve proved wrong.