Vane Arc Segment Seal for CMC Airfoil Cooling
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Solution Overview
Problem
Implementing ceramic matrix composite (CMC) materials in gas turbine airfoils poses challenges due to their high temperature resistance, particularly in sealing and cooling air flow effectively within the complex geometries of vane arc segments.
Innovation Solution
The vane arc segment design includes an airfoil fairing with a hollow section, a spar leg, and baffles with impingement holes, along with seals and support platforms to create plenum and impingement spaces for efficient cooling, where a baffle divides the gap between the spar leg and airfoil wall, and seals prevent leakage between the airfoil wall and spar leg.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are used in airfoils for high temperature resistance, then temperature capability is improved, but sealing and cooling air flow becomes more difficult due to complex geometries
Solution Approach 1:
The airfoil is divided into modular CMC segments that can be assembled together, allowing the complex geometry to be managed in discrete, manufacturable units while maintaining high temperature resistance. The segmentation also facilitates integration of cooling channels and sealing features in each module.
Solution Approach 2:
A seal is introduced as an intermediary component between the airfoil wall and spar leg to prevent cooling air leakage. This mediator element enables effective sealing in the complex CMC geometry without requiring direct metal-to-metal contact or complex machining.
2Temperature
If cooling air is directed onto the airfoil wall through impingement holes, then cooling efficiency is improved, but cooling air may escape through gaps reducing effectiveness
Solution Approach 1:
The harmful leakage path is extracted and isolated by introducing a seal that specifically targets the gap between the spar leg and airfoil wall. This removes the energy loss pathway while preserving the beneficial impingement cooling effect.
Solution Approach 2:
The seal is positioned in advance to prevent cooling air leakage before it can escape through the gap. By establishing the seal beforehand, the system ensures that cooling air remains contained and directed onto the airfoil wall through the impingement holes, maintaining cooling effectiveness.
3Ease of operation
If a baffle is used to divide the gap into plenum and impingement spaces, then cooling air flow control is improved, but device complexity increases
Solution Approach 1:
The baffle introduces a spatial dimension to separate the cooling air flow into distinct functional zones. By creating vertical separation between the plenum space (for air distribution) and impingement space (for cooling action), the system achieves precise flow control without requiring complex valve or actuator systems.
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 enhances the cooling efficiency of CMC airfoils by directing cooling air effectively onto the airfoil wall through impingement holes and maintains a sealed environment to prevent cooling air from escaping, thereby improving the thermal management and performance of gas turbine engines.
Implementation Method 1
A baffle is disposed in the first gap. The baffle is spaced apart from the airfoil wall and the spar leg so as to divide the first gap into a plenum space between the spar leg and the baffle and an impingement space between the baffle and the airfoil wall. The baffle has impingement holes directed toward the airfoil wall and connects the plenum space with the impingement space.
Implementation Method 2
A seal is disposed between the airfoil wall and the spar leg. The seal seals the impingement space from the second gap.
Data Source
Figure 1~2
Figure 3~4
Figure 5~9
AI summary
A vane arc segment (60) includes an airfoil wall (63) that defines first and second fairing platforms (66, 68) and a hollow airfoil section (64). A spar leg (72b) extends through the hollow airfoil section (64) and has an end portion that protrudes from the hollow airfoil section (64). The spar leg (72b) is spaced from the airfoil wall (63) in the hollow airfoil section (64) such that there is a first gap (78). There is a support platform (74) adjacent the second fairing platform (68) and a second gap (84) therebetween. A baffle (80) is disposed in the first gap (78) and is spaced apart from the airfoil wall (63) and the spar leg (72b) so as to divide the first gap (78) into a plenum space (78a) between the spar leg (72b) and the baffle (80) and an impingement space (78b) between the baffle (80) and the airfoil wall (63). A seal (86) is disposed between the airfoil wall (63) and the spar leg (72b) to seal the impingement space (78b) from the second gap (84).