Gas Turbine Face Seal Carrier Geometry for Lightweight Retention
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Solution Overview
Problem
Face seal assemblies in gas turbine engines face challenges in designing a lightweight yet strong seal carrier that withstands the stresses of the interference fit of carbon seals and avoids bending due to spring load, while maintaining proper fit with surrounding hardware, which leads to increased wear and heat generation.
Innovation Solution
A face seal assembly with a seal carrier featuring a main plate portion, a cylindrical body, and a seal retention structure including a first, second, and base seal wall defining a groove, where the second seal wall extends radially to a non-uniform location, and the geometry allows the seal to be installed in a single orientation, reducing mass and preventing incorrect installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seal retaining feature is integral to the seal carrier, then the seal is retained securely, but the mass of the carrier increases
Solution Approach 1:
The second seal wall is divided into multiple segments arranged circumferentially around the groove, with gaps between them. This segmentation reduces the total material required while maintaining the seal retention function, as the segments collectively provide the necessary structural support without requiring a continuous, heavy wall structure.
Solution Approach 2:
The seal retention structure uses non-uniform radial extension of the second seal wall segments, creating varying wall thicknesses and structural properties at different circumferential locations. This allows the carrier to have sufficient strength where needed while minimizing mass in less critical areas, optimizing the balance between reliability and weight.
2Strength
If the carrier mass is increased to withstand interference fit stresses, then the structural strength is improved, but the wear rate and heat generation increase
Solution Approach 1:
By segmenting the second seal wall into multiple circumferential sections with gaps between them, the carrier achieves the necessary structural strength to withstand interference fit stresses while reducing overall mass. The segmented structure distributes mechanical loads effectively across multiple support points, preventing excessive wear and heat generation that would occur with a heavier, monolithic design.
3Weight of moving object
If the seal carrier is made lightweight, then the wear and heat generation are reduced, but the carrier may bend under spring load and interference fit stresses
Solution Approach 1:
The second seal wall segments extend radially outwardly to non-uniform radial locations, creating a structure with varying local stiffness. This allows the carrier to be lightweight overall while maintaining sufficient rigidity in critical areas to resist bending under spring loads and interference fit stresses, optimizing the strength-to-weight ratio.
Solution Approach 2:
The seal retention structure utilizes the radial dimension by extending the second seal wall segments outwardly from the groove, creating a three-dimensional structure that provides both weight reduction and bending resistance. The radial extension of segments adds structural stability without significantly increasing the axial or circumferential dimensions of the carrier.
4Manufacturing precision
If the second seal wall extends to a non-uniform radial location, then the seal alignment is improved, but the manufacturing complexity increases
Solution Approach 1:
The second seal wall is divided into multiple segments that can be manufactured separately and then assembled into the carrier. This segmentation simplifies the manufacturing of each individual segment, allowing for easier machining of the non-uniform radial locations, while the final assembled structure provides the precise seal alignment required for proper function.
Data Source
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AI summary
A face seal assembly includes a seal (62). The assembly also includes a seal carrier (60) including a first seal wall, (82) a second seal wall (84) and a base seal wall (86), the first seal wall, the second seal wall and the base seal wall defining a groove (88) for receiving the seal (62) therein, the second seal wall (84) extending radially outwardly to a non-uniform radial location.