CMC Intersegment Seal for Blade Outer Air Seal Gap Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gas turbine engine blade outer air seal technologies face challenges in ensuring effective sealing while maintaining structural integrity and efficiency, particularly in high-temperature environments and varying thermal conditions.
Innovation Solution
A blade outer air seal assembly utilizing a ceramic matrix composite intersegment seal with a curved inner surface and a flat or curved outer surface, secured by a metallic clip with spring-loaded tabs, which biases the seal radially inward and self-centers over the intersegment gap, reducing material waste by reusing densified ceramic material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional metallic seals are used, then structural strength is improved, but weight increases and thermal capability decreases
Solution Approach 1:
The patent employs a composite structure combining ceramic matrix composite (CMC) material for the seal body with a metallic clip assembly for mechanical retention. The CMC portion provides high-temperature capability and weight reduction, while the metallic clip provides structural strength and elastic biasing force. This composite approach resolves the contradiction by assigning different material functions to different components of the sealing system.
2Weight of moving object
If ceramic matrix composite material is used, then weight is reduced and thermal capability is improved, but structural rigidity decreases
Solution Approach 1:
The hybrid CMC-metalic clip structure provides the necessary structural rigidity that CMC alone cannot achieve. The metallic clip acts as a reinforcement element that maintains the sealing force and positional stability while allowing the CMC seal body to provide weight reduction and thermal resistance.
Solution Approach 2:
The metallic clip is strategically positioned to provide localized structural support and elastic biasing force where needed, while the CMC material is used in regions requiring thermal resistance and weight reduction. This spatial differentiation of material properties resolves the rigidity-weight-thermal capability triangle.
3Reliability
If the intersegment seal is biased radially inward, then sealing effectiveness is improved, but the risk of delamination increases
Solution Approach 1:
The spring-loaded radial tabs provide a controlled, elastic biasing force that can be adjusted through the spring rate and preload. This allows optimization of the radial inward force to achieve adequate sealing while maintaining sufficient compressive stress distribution to prevent delamination of the CMC layers.
Solution Approach 2:
The elastic spring elements in the radial tabs provide a cushioning effect that absorbs thermal expansion and contraction stresses, preventing excessive localized stresses that could cause delamination while maintaining continuous sealing contact.
4Ease of manufacture
If densified ceramic material is reused, then manufacturing cost is reduced, but manufacturing complexity increases
Solution Approach 1:
The densification of ceramic material is performed in advance during the manufacturing process, creating a pre-densified ceramic body that can be subsequently machined and assembled. This preliminary densification step enables cost-effective reuse of ceramic material while simplifying subsequent manufacturing operations.
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 provides a lightweight, cost-effective, and thermally capable sealing solution that self-centers and maintains structural rigidity, reducing the risk of delamination and weight compared to traditional metallic seals, while ensuring effective sealing across varying thermal conditions.
Implementation Method 1
The radial tab is a spring loaded tab
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A blade outer air seal assembly (104) includes a blade outer air seal (106) that has a plurality of segments (105) that extend circumferentially about an axis and are mounted in a carrier (112). At least two of the plurality of segments (105) have a first wall (120) and a second wall (122) circumferentially spaced from one another and a base portion (124) that extends from the first wall (120) to the second wall (122). The base portion (124) extends circumferentially outward past the first and second walls (120, 122) to form first and second sealing surfaces (125, 127). An intersegment seal (150) has a curved surface (152). The curved surface (152) is engaged with the first and second sealing surfaces (125, 127) between the at least two segments.