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Introduction
1-4
abnormality in the flow path. Adoption of proven aviation technology has minimized leakage
paths and has improved clearance control. These aviation to industrial transfer technology
trends, which can be considered low to medium risk with respect to product reliability include:
• Advanced compressor designed flow paths
− Controlled diffusion airfoils
− Multiple circular arc airfoils
− Double circular arc airfoils
− 2D and 3D aerodynamics
− Variable vanes
− Shrouded stators with improved labyrinth seals
− Increased surge margins
− Exit (outlet) guide vanes
• Active and Passive Clearance and leakage control
Advanced Aero Technology Trends Transferred to Industrial Combustion
Turbines: Medium to High Risk
Hot end technology transferred to industrial turbines with firing temperatures in the
2300
o
- 2600
o
F (1260
o
– 1427
o
C) range has been a challenge because of the duty cycle imposed
on the land-based turbine. The advanced materials (e.g. single crystal [SC] castings), exotic
cooling schemes, advanced coatings, and clearance control all had to be scaled to the sizes
utilized in the larger frame sized combustion turbine. Designing the 3D aerodynamic flow path
and providing adequate cooling for all the required blade and vane rows without exceeding base
metal temperature was required while maintaining durability, acceptable stress levels, and
vibratory characteristics.
The manufacturing of turbine blades and vanes with single crystal technology and the
development of appropriate coatings and bond coatings for these materials is a challenge for the
designers and manufacturers and currently should be classified as medium to high risk due to the
current level of experience in the field. These advanced aviation to industrial transfer technology
trends, which can be considered medium to high risk with respect to product reliability include:
• Turbine flow path
• 2D and 3D aerodynamics
• Advanced cooling technology*
− Convection cooling schemes
− Impingement cooling schemes
− Film cooling schemes