Ceramic Runner Mount Assembly for Stable Circumferential Sealing
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Solution Overview
Problem
The primary challenge in utilizing ceramic runners within circumferential seals in gas turbine engines is the flexible mount structure, which affects the sealing efficiency and reliability.
Innovation Solution
A runner assembly with a retainer assembly that includes a radially flexible clamp, an axial retainer, and an axial spring provides a resilient mount for the ceramic runner, allowing for minimal impact loads and accommodating axial movement, while maintaining a constant gap with the carbon sealing ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flexible mount structure is used to accommodate thermal and mechanical growth of the ceramic runner, then the sealing performance is improved, but the complexity of the device increases
Solution Approach 1:
The mount structure is divided into separate functional components: a resilient mount assembly with radially flexible clamp and axial retainer, and the ceramic runner itself. This segmentation allows each component to be optimized independently - the resilient mount handles thermal/mechanical growth while the ceramic runner maintains sealing surface integrity.
Solution Approach 2:
The mount structure incorporates dynamic elements including a radially flexible clamp that can deform radially to accommodate thermal expansion, and an axial spring that allows axial movement. This dynamic capability enables the structure to adapt to changing operating conditions without compromising sealing performance.
2Reliability
If a resilient mount with axial spring is used to accommodate axial movement, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The axial spring is pre-loaded to provide cushioning against axial movement before it occurs during operation. This beforehand cushioning protects the ceramic runner from impact loads and accommodates axial thermal growth, improving reliability while using a relatively simple spring element rather than a complex active control system.
3Reliability
If a radially flexible clamp is used to accommodate thermal growth, then the sealing performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The radially flexible clamp functions as a flexible structural element that can deform radially to accommodate thermal growth of the ceramic runner. This flexible design allows the clamp to adapt to dimensional changes without requiring complex adjustment mechanisms, and can be manufactured as an integrated component with appropriate material selection and cross-sectional geometry.
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 ensures a more consistent sealing performance throughout the engine's operating envelope by effectively managing thermal and mechanical growth, reducing fluid leakage, and providing a cost-effective and reliable sealing solution.
Implementation Method 1
an axial spring which provides a clamping load on the inwardly extending mounting flange
Implementation Method 2
A runner assembly with a retainer assembly that includes a radially flexible clamp, an axial retainer, and an axial spring provides a resilient mount for the ceramic runner, allowing for minimal impact loads and accommodating axial movement, while maintaining a constant gap with the carbon sealing ring
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A runner assembly for a circumferential seal assembly includes a runner (70) having an inwardly extending runner mounting flange (78), a flexible mounting structure and a retainer assembly therefor. In one embodiment, a radially flexible clamp (80) engages the flange (78) and an axial retainer (82) traps an axial spring (84) between the axial retainer (82) and the runner (70).