Graded Abradable Seal Structure for Gas Turbine Leakage Control
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Solution Overview
Problem
The existing methods for fabricating abradable seals for gas turbine engines are complex and expensive due to the need for separate processes, as investment casting is not suitable for forming abradable seals on airfoils, and existing seal systems do not effectively control abradability to optimize sealing performance.
Innovation Solution
The abradable seal features a cellular structure with cell walls and cores made of different materials, such as metallic and ceramic, with varying abradability characteristics by locality, allowing for tailored wear patterns and enhanced sealing, achieved through additive manufacturing processes that enable compositionally graded and porous structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If abradable seals are fabricated using separate processes (not investment casting), then the seals can be formed on airfoils, but the fabrication complexity and cost increase
Solution Approach 1:
The patent combines the airfoil and abradable seal into a single integrated component manufactured through additive manufacturing. The seal is built directly on the airfoil surface in one continuous process, eliminating the need for separate fabrication and assembly steps. This merging of components resolves the technical contradiction by maintaining adaptability while reducing fabrication complexity.
Solution Approach 2:
The patent utilizes additive manufacturing parameters (layer thickness, infill density, material composition) to directly form the abradable seal geometry on the airfoil surface. By changing manufacturing parameters during the additive process, the seal structure is adapted to the airfoil contour without requiring separate tooling or assembly operations, thus reducing overall fabrication complexity.
2Ease of manufacture
If uniform material composition is used in abradable seal, then manufacturing is simpler, but sealing performance cannot be optimized through controlled wear patterns
Solution Approach 1:
The patent implements local quality variations within the abradable seal by incorporating regions of different material composition, porosity, or hardness at specific locations. The additive manufacturing process enables spatial variation of material properties, creating zones with different abradability characteristics that produce controlled wear patterns for optimized sealing performance while maintaining relatively simple overall manufacturing.
Solution Approach 2:
The patent employs composite materials with varying compositions (e.g., metal matrix composites, ceramic-polymer blends) within the abradable seal structure. Different composite formulations are deposited in specific regions during additive manufacturing to achieve desired wear characteristics, balancing manufacturing simplicity with precise sealing performance control through material heterogeneity.
3Reliability
If tight clearance gap is achieved through abrasion, then flow leakage is reduced, but the seal material must be consumable and wear away
Solution Approach 1:
The patent designs the abradable seal with the understanding that certain material will be consumed through controlled wear to achieve the tight clearance gap. The additive manufacturing process compensates for this material loss by building the seal with excess material that progressively wears down to the optimal sealing dimension, ensuring reliable sealing while accounting for the necessary material discarding.
Solution Approach 2:
The patent incorporates additional material volume in the additively manufactured seal structure that serves as a cushion for future wear. This excess material is deliberately built during manufacturing to compensate for the material that will be consumed during operation, ensuring that the seal maintains its sealing effectiveness over time while managing the expected material loss.
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
This approach simplifies the fabrication process, reduces costs, and optimizes sealing performance by controlling abradability to create desirable wear patterns, thereby enhancing engine efficiency and reducing flow leakage.
Implementation Method 1
Abradable seals can be fabricated with a porous material that, when abraded by a mating structure, wears away to form a groove or wear pattern that provides the tight clearance gap
Implementation Method 2
Abradable seals can be fabricated with a porous material that, when abraded by a mating structure, wears away to form a groove
Data Source
Figure 1~6
Figure 2~5
AI summary
An abradable seal (64; 164; 264) for a gas turbine engine includes a seal body (66) that has a seal side (66a) and a non-seal side (66b). The seal body (66) includes an abradability characteristic that varies by locality, wherein the abradability characteristic is selected from the group consisting of a graded composition, a graded porosity, a non-uniform geometric cell structure and combinations thereof.