Compliant Rotor Seal Assembly for Misaligned Annular Gaps
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Solution Overview
Problem
Existing gas turbine engine seal assemblies face challenges in effectively sealing annular gaps between rotating structures, particularly when these structures are misaligned, leading to inefficiencies and potential fluid leakage.
Innovation Solution
A seal assembly is designed with a flexible arm cantilevered from one rotating structure, connected to a seal element that forms a seal interface with a seal land on another rotating structure, accommodating misalignment and utilizing a bearing to support the seal element, thereby ensuring a compliant and effective seal across the annular gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid seal assembly is used between rotating structures, then sealing effectiveness is improved, but adaptability to misalignment deteriorates
Solution Approach 1:
The seal assembly incorporates a flexible arm that can dynamically adjust its position and orientation in response to misalignment between rotating structures. The arm's flexibility allows the seal element to maintain contact with the seal land while accommodating angular and radial deviations, thus preserving sealing effectiveness without requiring perfect alignment.
Solution Approach 2:
The seal assembly uses a flexible arm constructed from compliant materials or with a laminated structure that provides controlled flexibility. This flexible component can bend and deform to accommodate misalignment between rotating structures while maintaining the seal interface, resolving the contradiction between rigid sealing and adaptability.
2Adaptability or versatility
If a flexible seal assembly is used to accommodate misalignment, then adaptability is improved, but sealing effectiveness deteriorates
Solution Approach 1:
The flexible arm is designed with non-uniform stiffness characteristics - stiffer near the mounting point to maintain positioning accuracy, and more compliant near the seal element to accommodate misalignment. This gradient in flexibility allows the structure to adapt to misalignment while maintaining sufficient rigidity at the seal interface to ensure effective sealing.
Solution Approach 2:
The flexible arm provides dynamic adaptation to misalignment while maintaining stable contact at the seal interface. The arm's controlled flexibility allows it to absorb misalignment movements without compromising the seal element's ability to maintain a reliable seal with the seal land.
3Reliability
If the seal element is made rigid to improve seal interface stability, then sealing effectiveness is improved, but ability to accommodate misalignment deteriorates
Solution Approach 1:
The seal assembly is segmented into distinct functional components: a flexible arm for accommodation, a rigid seal element for stable sealing, and a seal land for interface formation. This segmentation allows each component to perform its specific function - the arm absorbs misalignment while the seal element maintains stable, effective sealing contact.
Solution Approach 2:
The seal element is designed with localized rigidity at the sealing surface to ensure stable contact and effective sealing, while the arm portion remains flexible to accommodate misalignment. This spatial variation in mechanical properties resolves the contradiction between interface stability and adaptability.
4Adaptability or versatility
If the arm is made more flexible to improve misalignment accommodation, then adaptability is improved, but structural strength deteriorates
Solution Approach 1:
The flexible arm is constructed using composite materials or a laminated structure that provides controlled flexibility in specific directions while maintaining sufficient structural strength. The composite construction allows the arm to bend and accommodate misalignment without compromising the strength needed to support the seal element and resist operational loads.
Solution Approach 2:
The arm is designed with spatially varying mechanical properties - stiffer near the mounting point to maintain structural integrity and positioning, and more flexible near the seal element to accommodate misalignment. This gradient in stiffness allows the arm to be sufficiently flexible for adaptation while maintaining the structural strength required for operational reliability.
Data Source
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Figure 3~4
AI summary
An assembly for an aircraft includes a first rotating structure (80; 136), a second rotating structure (81; 138) and a seal assembly (134). The seal assembly (134) is configured to seal an annular gap (140) radially between the first rotating structure (80; 136) and the second rotating structure (81; 138). The seal assembly (134) includes an arm (142), a seal element (144) and a seal land (146). The arm (142) is cantilevered from and extends axially along the second rotating structure (81; 138). The seal element (144) is connected to the arm (142) and forms a seal interface with the seal land (146). The seal land (146) is connected to the first rotating structure (80; 136).