Turbomachine Blade Root Seals Preventing Buckling
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Solution Overview
Problem
Conventional U-shaped feather seals in turbomachines tend to buckle under operational stress, leading to leaks between blade stages and reduced efficiency due to the inward pressure of their legs on the cross-portion, which is not effectively addressed by existing designs.
Innovation Solution
The design incorporates a blade root with dove-tail slots and separate, axially extending cross member slots that are radially outboard of leg slots, featuring variable thickness and bends to accommodate the cross member seal, preventing buckling and enhancing sealing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional U-shaped feather seals are used in blade roots, then the sealing structure is simple and easy to manufacture, but the seals buckle under operational stress leading to leaks and reduced efficiency
Solution Approach 1:
The blade root seal structure is segmented into multiple independent components: a cross member seal and multiple leg seals (forward leg seal and aft leg seal). Each seal is positioned in its own dedicated slot, allowing them to function independently without buckling into each other. This segmentation resolves the technical contradiction by improving reliability through independent seal operation while managing device complexity through modular design.
Solution Approach 2:
The seal slots are arranged in different spatial dimensions and orientations. The cross member slot extends axially while the leg slots extend radially, creating a three-dimensional seal configuration. This dimensional arrangement prevents the seals from buckling into each other under operational stress, improving reliability while the systematic arrangement keeps the overall structure manageable.
2Strength
If separate cross member slots and leg slots are used with variable thickness, then the seals resist deformation better, but the manufacturing complexity increases
Solution Approach 1:
The leg slots feature variable thickness with different sections having different thicknesses. The thickness varies along the radial extent of the leg slots, providing enhanced structural support where needed while maintaining flexibility in other areas. This local quality variation improves the seals' resistance to deformation under operational stress, addressing the strength requirement while the systematic variation pattern facilitates manufacturing.
Data Source
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AI summary
A turbomachine blade assembly (100a) comprises at least two blades (100) assembled adjacent each other and defining a gap (G) as well as three feather seals (207, 209a, 209b), each blade including a blade root (101) defining three feather seal slots on a lateral portion thereof. The seal slots include two leg slots (109a, 109b), each leg slot extending radially, and a cross member slot (107) extending axially. An airfoil portion (103) extends radially from the blade root.