Turbine Exhaust Diffuser Seal Reduces Out-of-Round Deformation
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Solution Overview
Problem
Gas turbine engines with split exhaust diffusers experience high out of round conditions due to thermal stresses and radial flanges, affecting aero-performance and efficiency.
Innovation Solution
An outer forward seal system with a detachable seal base and dowel locking mechanism is introduced, reducing the radial height of the diffuser and minimizing out of round conditions while maintaining effective sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a split diffuser is used to provide operational flexibility and access to components, then ease of operation is improved, but out of round conditions increase due to thermal stresses on tall radial flanges
Solution Approach 1:
The diffuser is divided into multiple segments that can be separated from each other, allowing access to internal components while reducing the size of individual flanges. The segments are connected via sealing interfaces that maintain structural integrity without requiring tall radial flanges, thereby reducing thermal stress and out-of-round conditions.
Solution Approach 2:
The sealing interface transitions from a radial flange configuration to an axial sealing arrangement. The seal base and seal member are positioned axially within the diffuser segment, eliminating the need for tall radial flanges and reducing the moment arm for thermal stresses.
2Ease of manufacture
If tall radial flanges are used for sealing and attachment in split diffusers, then ease of manufacture is improved, but stress on the diffuser skin increases due to thermal gradients
Solution Approach 1:
The sealing mechanism is repositioned from a radial flange interface to an axial sealing arrangement using a seal base and seal member. This dimensional change reduces the lever arm for thermal stresses and concentrates sealing forces in the axial direction, minimizing bending moments on the diffuser skin.
Solution Approach 2:
A flexible seal member is introduced to accommodate thermal expansion and contraction of the diffuser segments. The flexible seal compensates for dimensional changes due to thermal gradients, reducing stress concentrations on the rigid diffuser skin while maintaining effective sealing.
3Ease of manufacture
If a continuous 360 degree diffuser is used, then manufacturing ease is improved, but operational flexibility is reduced compared to split diffusers
Solution Approach 1:
The continuous diffuser is segmented into multiple sections that can be separated axially or radially. The segments are equipped with sealing interfaces using seal bases and seal members, allowing the diffuser to function as a continuous structure during operation while enabling access to internal components when separated for maintenance or inspection.
4Shape
If the radial height of the diffuser is reduced to minimize out of round conditions, then shape stability is improved, but sealing effectiveness may be compromised
Solution Approach 1:
A flexible seal member is positioned within a seal base that extends axially into the diffuser segment. The flexible seal can deform to accommodate radial and axial movements, maintaining effective sealing even with reduced radial height. The seal member compensates for dimensional variations and ensures reliable sealing without requiring tall radial flanges.
Solution Approach 2:
A seal base acts as an intermediary structure between the diffuser segment and the seal member. The seal base provides a stable mounting position for the seal member and distributes sealing forces over a larger area, ensuring effective sealing while allowing the overall radial height of the diffuser to be reduced.
Data Source
AI summary
The present application provides an exhaust diffuser. The exhaust diffuser may include an outer diffuser section with a forward portion. An outer forward seal system may be positioned on the forward portion. The outer forward seal system may include a seal base removably positioned in a seal pocket.