Bulbed Dead Ended Rib for Gas Turbine Cooling
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Solution Overview
Problem
Current gas turbine engine cooling circuits with dead ended ribs experience high stress concentrations due to centrifugal forces, which limits their Low Cycle Fatigue life and overall durability.
Innovation Solution
The implementation of a bulbed rib profile with a rib draft and variable sized blend in the dead ended rib geometry to reduce stress concentrations, facilitating a smoother transition and distributing stress away from the rib, thereby enhancing the durability of actively cooled components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dead ended rib is used in serpentine cooling passages, then the cooling circuit can be effectively implemented, but stress concentrations occur due to centrifugal forces
Solution Approach 1:
The rib profile is modified to include a curved transition zone instead of sharp angles, creating a more spherical/curved geometry at the rib root and dead-ended portion. This curvature distributes stress more evenly and eliminates stress concentration points, directly resolving the contradiction between maintaining cooling effectiveness and reducing stress.
Solution Approach 2:
The rib geometry parameters are optimized by varying the rib height, thickness, and curvature radius along its length. The dead-ended portion is designed with specific dimensional parameters that reduce stress concentration while maintaining structural integrity and cooling function, transforming the rib from a simple geometric feature to an optimized stress-distributing structure.
2Reliability
If current dead ended rib designs are used, then cooling passages can be formed, but Low Cycle Fatigue life is limited due to stress concentrations
Solution Approach 1:
The curved transition zones and optimized rib profile eliminate sharp corners and stress concentration points, creating a smoother stress distribution that significantly extends fatigue life. The spherical/curved geometry at critical locations prevents crack initiation and propagation, directly addressing the fatigue life limitation while preserving cooling passage functionality.
Solution Approach 2:
Specific geometric parameters of the rib structure are modified to optimize fatigue performance. The rib thickness, height, and curvature radii are adjusted to create a geometry that minimizes stress concentration factors, thereby extending Low Cycle Fatigue life while maintaining the structural and thermal functions of the cooling passages.
3Ease of manufacture
If conventional rib geometry is used in cooling circuits, then manufacturing is simplified, but fracture life is reduced due to stress concentrations
Solution Approach 1:
The curved transition zones and optimized rib profile eliminate sharp corners and stress concentration points, creating a smoother stress distribution that significantly extends fatigue life. The spherical/curved geometry at critical locations prevents crack initiation and propagation, directly addressing the fatigue life limitation while preserving cooling passage functionality.
Solution Approach 2:
Specific geometric parameters of the rib structure are modified to optimize fatigue performance. The rib thickness, height, and curvature radii are adjusted to create a geometry that minimizes stress concentration factors, thereby extending Low Cycle Fatigue life while maintaining the structural and thermal functions of the cooling passages.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces stress concentrations, increasing the Low Cycle Fatigue life and fracture life of gas turbine engine components with dead ended ribs, leading to improved durability and performance.
Implementation Method 1
turbine vanes and turbine blades are typically internally cooled with compressor air bled from a compressor section through one or more internal cooling passages
Implementation Method 2
Hot combustion gases flow along the stator vanes and the turbine blades such that the turbine vanes and turbine blades are typically internally cooled
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A component (32) within a gas turbine engine includes a dead ended rib (56) which at least partially defines an internal cooling circuit flow path (26), the dead ended rib defines a bulbed rib profile (58).