Knife Edge Seal Geometry for Crack-Resistant Turbine Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing knife edge seals in gas turbine engines are prone to cracking, which reduces their sealing efficiency and necessitates premature replacement, leading to inefficiencies and increased maintenance costs.
Innovation Solution
A modified knife edge seal design featuring a larger angle between the knife edge and the pedestal, with additional material away from the tip to slow crack propagation and act as a heat sink, using nickel-chromium alloys, and a smaller tip size to maintain sealing effectiveness while reducing mass and manufacturing limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional knife edge seal design is used, then the sealing function is provided, but cracks develop and propagate reducing reliability
Solution Approach 1:
The knife edge seal is divided into distinct functional zones: a tip portion for sealing contact and a body portion with additional material for crack resistance. This segmentation allows each zone to be optimized for its specific function while working together as an integrated component.
Solution Approach 2:
Additional material is strategically placed in specific locations away from the tip to create local reinforcement zones that slow crack propagation. The material distribution is non-uniform, with higher concentration in regions prone to crack initiation and propagation, while maintaining a sharp tip for sealing effectiveness.
2Reliability
If the knife edge seal material is increased to prevent cracks, then crack resistance improves, but the tip size increases reducing sealing effectiveness
Solution Approach 1:
The seal structure is segmented into a minimal tip portion for sealing and a reinforced body portion for crack resistance. This allows the tip to remain small and sharp for effective sealing while the body provides additional material for crack propagation resistance.
Solution Approach 2:
Material is added locally in specific regions away from the tip rather than uniformly throughout. This creates zones of enhanced crack resistance without increasing the critical tip dimensions that affect sealing performance.
3Reliability
If the knife edge seal operates in high temperature environment, then sealing function is maintained, but crack propagation accelerates
Solution Approach 1:
Additional material is incorporated in advance in regions where cracks are likely to initiate and propagate under thermal stress. This pre-positioned material acts as a buffer or cushion against crack propagation, slowing damage accumulation before it reaches critical levels.
Solution Approach 2:
The knife edge seal is made from nickel-chromium alloys, which are composite materials combining nickel and chromium elements. These alloys provide enhanced resistance to both high temperature environments and crack propagation, offering superior durability compared to single-element materials.
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 modified seal design enhances crack resistance and sealing efficiency, prolonging the component's life and reducing maintenance needs by mitigating crack propagation and maintaining effective sealing performance.
Implementation Method 1
additional material away from the tip to slow crack propagation and act as a heat sink
Data Source
Figure 1
Figure 2
AI summary
A knife edge seal includes a pedestal and a knife edge with a tip and a base. The base rests on the pedestal. The base has a first width and the tip has a second width, and the ratio of the first width to the second width is in the range of 5:1 to 15:1. A gas turbine engine and a method of sealing a high pressure area from a low pressure area are also disclosed.