Blade Outer Air Seal Silicon Coating Thermal Stability
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Solution Overview
Problem
Existing blade outer air seal arrangements in gas turbine engines face challenges in maintaining effective sealing across varying temperatures and operational conditions, particularly when using ceramic matrix composite (CMC) materials.
Innovation Solution
A blade outer air seal assembly featuring a silicon metal coating on the seal segments, which are machined to provide a smooth sealing surface and precise dimensional control. The coating is applied to both the first and second walls of the seal segments and extends onto the base portion, ensuring a secure and efficient seal. Additionally, a W-seal is used between the support structure and the seal plate to maintain axial alignment and minimize leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic matrix composite materials are used for blade outer air seal segments, then thermal stability is improved, but sealing performance deteriorates due to surface roughness
Solution Approach 1:
The patent applies a silicon metal coating over the ceramic matrix composite base material. This composite structure combines the thermal stability of CMC with the smooth sealing surface and thermal conductivity of silicon metal, resolving the contradiction between thermal stability and sealing performance
Solution Approach 2:
The silicon metal coating is applied selectively to the sealing surfaces (first and second walls) while the base portion maintains its CMC structure. This local application provides smooth sealing contact surfaces where needed while preserving the thermal stability of the CMC material in the bulk structure
2Temperature
If ceramic matrix composite materials are used for seal segments, then heat resistance is improved, but manufacturing precision deteriorates
Solution Approach 1:
The silicon metal coating layer serves as a precision surface that can be machined to tight tolerances, compensating for the difficulty of achieving precise dimensions directly in CMC material while maintaining the heat resistance of the underlying CMC structure
Solution Approach 2:
The coating is applied to specific surfaces requiring precision (sealing walls) and then machined separately, allowing high-precision machining of the coating layer without compromising the thermal properties of the CMC base material
3Manufacturing precision
If a coating is applied to seal segments, then sealing surface quality is improved, but device complexity increases
Solution Approach 1:
The silicon metal coating on CMC substrate creates a functionally graded structure that provides both the smooth sealing surface and thermal stability in a single integrated component, avoiding the need for separate sealing elements and reducing overall assembly complexity
Solution Approach 2:
The silicon metal coating performs multiple functions simultaneously: providing a smooth sealing surface, improving thermal conductivity at the sealing interface, and protecting the CMC material. This multi-functionality reduces the need for additional components
Data Source
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AI summary
A flow path component assembly (104; 204) includes a flow path component having a plurality of segments (105) that extend circumferentially about an axis and mounted in a support structure (110; 210). At least one of the plurality of segments (105) have a first wall (120) and a second wall (122) that extend radially outward from a base portion (124). The first wall (120) is axially spaced from the second wall (122). A coating is on a portion of the first wall (120) and a portion of the second wall (122). The coating is in contact with a feature (142; 242) on the support structure (110; 210).