CMC Edge Seal Offset Ply Protrusion Recess Leakage
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Solution Overview
Problem
Existing edge seal technologies for gas turbine engine components, such as blades and vanes, face challenges in effectively sealing edges to reduce fluid flow and leakage, particularly in ceramic matrix composite materials.
Innovation Solution
The implementation of an offset ply layup method to create integral projections and recesses in ceramic matrix composite components, forming a tortuous path for fluid leakage, which can be machined or formed during fabrication processes, to enhance sealing between gas turbine engine components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sealing methods are used for CMC components, then assembly is simplified, but fluid leakage between components increases
Solution Approach 1:
The edge seal is segmented into multiple plies with different orientations and properties. The first ply extends beyond the second ply to create a protrusion, while the second ply forms a recess area. This segmentation allows each ply to contribute differently to the sealing function, creating tortuous paths for fluid leakage while maintaining overall structural integrity.
Solution Approach 2:
Different regions of the edge seal are given different local qualities through the ply configuration. The first ply provides a protruding sealing lip in one area, while the second ply creates a recess in another area. This local differentiation enables the seal to adapt to varying stress and fluid flow conditions at different locations along the edge.
2Reliability
If offset plies are used to create projection and recess, then fluid leakage is reduced, but manufacturing complexity increases
Solution Approach 1:
The offset ply configuration is built into the structure during the preliminary layup process rather than being added later. The first and second plies are positioned with their offsets during initial assembly, creating the projection and recess features before infiltration. This preliminary action simplifies the overall manufacturing process by combining sealing feature creation with the base structure fabrication.
Solution Approach 2:
The edge seal utilizes composite material construction with multiple plies of fiber reinforcement embedded in matrix material. The different plies can have varying fiber orientations, material compositions, and thicknesses, allowing optimization of both sealing performance and manufacturability through material selection and layering strategies.
3Reliability
If integral projection and recess are formed, then tortuous paths for fluid leakage are created, but local bending stresses increase
Solution Approach 1:
The sealing mechanism transitions from a two-dimensional flat interface to a three-dimensional structure with protrusions and recesses. By adding the dimension of depth through offset plies, the seal creates tortuous paths that fluid must navigate, significantly reducing leakage potential while the distributed ply structure helps manage the resulting stresses.
Solution Approach 2:
The multi-ply construction allows the edge seal to exhibit dynamic behavior under load. The different plies can deform independently to some extent, allowing the structure to flex and adapt to thermal and mechanical stresses while maintaining the sealing geometry. This dynamic capability helps distribute bending stresses more evenly throughout the structure.
Data Source
AI summary
A gas turbine engine ceramic matrix composite (CMC) component includes first and second outer layers of plies, and an intermediate layer of plies between the first and second outer layers of plies. The intermediate layer of plies is offset relative to the first and second outer layers of plies. The offset forms a protrusion on one side of the CMC component and a recess in an opposite side of the CMC component such that when two CMC components are assembled together, the protrusion of the one CMC component engages the recess of the other CMC component to form an edge seal between the CMC components.