Featherseal Tab Locking Mechanism for Turbine Leakage Control
Solution Overview
Problem
Existing featherseals in gas turbine engines require expensive hardcoating and bending operations to prevent wear and leakage, which increases manufacturing costs and can lead to premature wear and increased fluid leakage.
Innovation Solution
A blade outer air seal assembly featuring a featherseal with first and second lateral tabs that create a tab space engaging a post, eliminating the need for hardcoating and bending, and providing a locking mechanism to prevent fore-aft movement and minimize fluid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hardcoating operation is applied to the radial tab, then wear resistance is improved, but manufacturing cost increases and surface roughness increases leading to increased leakage
Solution Approach 1:
The patent replaces the expensive hardcoated radial tab with an inexpensive axial tab made of the same material as the featherseal body. The axial tab is designed to be replaceable and less critical, allowing the use of cheaper materials and manufacturing methods while maintaining adequate service life for the application.
Solution Approach 2:
The patent changes the orientation of the tab from radial to axial, and modifies the engagement mechanism from bending-based to insertion-based through a transverse slot. This parameter change eliminates the need for hardcoating while maintaining wear resistance through proper material selection and geometric design.
2Strength
If hardcoating operation is applied to the radial tab, then wear resistance is improved, but fluid leakage increases due to rough surface
Solution Approach 1:
The axial tab is made from the base material without expensive hardcoating, accepting that it may wear faster but is replaceable. The smooth surface of the uncoated tab reduces fluid leakage compared to the rough hardcoated surface, and the tab can be replaced when wear occurs.
Solution Approach 2:
Changing the tab orientation to axial and using a transverse slot engagement mechanism allows the tab to maintain wear resistance through material selection and geometry rather than surface coating, resulting in a smoother surface that reduces fluid leakage.
3Ease of manufacture
If radial tab is not hardcoated, then manufacturing cost decreases, but wear resistance decreases leading to rapid wear and component failure
Solution Approach 1:
The featherseal is segmented into the main body and a separate axial tab component. This allows the tab to be optimized for low cost and ease of manufacture while the main body maintains the sealing function. The tab can be replaced independently when worn, extending the overall service life of the sealing system.
Solution Approach 2:
The engagement mechanism is made dynamic with the transverse slot allowing the axial tab to be inserted and locked in place. This provides adequate retention during operation while allowing for easy replacement when wear occurs, optimizing the balance between service life and manufacturing cost.
4Ease of manufacture
If radial tab is not hardcoated, then manufacturing cost decreases, but featherseal stability decreases due to rapid wear
Solution Approach 1:
By segmenting the featherseal into body and tab components with independent replaceability, the system maintains stability through the permanent body while allowing the tab to be refreshed. This segmentation enables cost reduction without sacrificing overall assembly stability.
Solution Approach 2:
The dynamic insertion and locking mechanism through the transverse slot provides sufficient stability during operation while enabling easy replacement. The design achieves an optimal balance between operational stability and ease of manufacture/replacement.
Data Source
Figure 1
Figure 2A
Figure 2B~3
AI summary
An air seal assembly (10) includes a featherseal (76) engaged between adjacent turbine engine components (54) to close a gap therebetween. The featherseal (76) includes a first lateral tab (80) and a second lateral tab (82) which defines a tab space (84) therebetween. The tab space (84) locks the featherseal (76) into the turbine engine component (54) to prevent fore-aft movement thereof.