CMC Vane Radial Seal for Cooling Air Leakage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Implementing ceramic matrix composite (CMC) materials in gas turbine engine airfoils faces challenges due to thermal expansion differences between CMCs and metallic components, leading to potential leakage of cooling air and retention issues of seals in varying temperature conditions.
Innovation Solution
A ceramic matrix composite (CMC) vane arc segment with internal through-cavity and metallic vane supports, featuring a seal radially located between platforms and supports to limit cooling air leakage, utilizing rope or tadpole seals secured by fasteners or eyelets to maintain sealing despite thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are used in airfoils to extend temperature capability, then temperature resistance is improved, but thermal expansion differences cause seal retention issues
Solution Approach 1:
The seal is designed to change its physical state from a compressed condition during assembly to an expanded condition during operation. The compression member compresses the seal in the radial direction during assembly, but thermal expansion during operation causes the seal to expand and contact the CMC airfoil, maintaining the seal despite thermal expansion differences between CMC and metallic components.
Solution Approach 2:
The seal transitions from a static compressed state during assembly to a dynamic state where thermal expansion actively engages the seal with the airfoil surface. This dynamic adaptation allows the seal to maintain contact and sealing effectiveness across varying temperature conditions.
2Reliability
If seals are installed to prevent cooling air leakage, then sealing performance is improved, but thermal expansion causes potential leakage
Solution Approach 1:
The seal's physical dimensions change in response to temperature. During operation, thermal expansion causes the seal to expand radially, ensuring continuous contact with the CMC airfoil surface and preventing cooling air leakage despite the thermal expansion differences between materials.
Solution Approach 2:
The seal system provides automatic feedback adjustment through thermal expansion. As temperature increases, the seal naturally expands to maintain contact pressure with the airfoil, self-regulating the sealing force without external intervention.
3Manufacturing precision
If compression members are used to secure seals, then seal positioning is improved, but thermal variations cause retention issues
Solution Approach 1:
The compression member is designed to allow thermal expansion of the seal while maintaining positioning. The member provides initial compression for precise positioning during assembly, then accommodates thermal expansion during operation, preventing seal retention issues under thermal variations.
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
The solution effectively reduces cooling air leakage and maintains seal integrity by compressively loading seals, accommodating thermal variations, and ensuring proper positioning and retention, enhancing the sealing performance of CMC airfoils.
Implementation Method 1
The seal circumscribes the platform outlet port to limit leakage of the cooling air between the CMC vane and the metallic vane support
Implementation Method 2
thermal expansion differences between CMCs and metallic components, leading to potential leakage of cooling air and retention issues of seals in varying temperature conditions
Data Source
AI summary
A gas turbine engine includes a ceramic matrix composite (CMC) vane arc segment that has first and second platforms and an airfoil section that extends radially therebetween. The airfoil section includes an internal through-cavity, and the first and second platforms include, respectively, platform inlet and outlet ports connected to the internal through-cavity for conveying cooling air. The CMC vane arc segment is radially mounted between first and second metallic vane supports. The second metallic vane support includes a plenum and a plenum inlet port connected with the platform outlet port for receiving the cooling air from the internal through-cavity. There is a seal located radially between the second platform and the second metallic vane support. The seal circumscribes the platform outlet port to limit leakage of the cooling air between the second platform and the second metallic vane support.