Micro-porous Abradable Seal for Gas Turbine Aerodynamic Efficiency
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Solution Overview
Problem
Existing abradable seals in gas turbine engines with large pores cause aerodynamic efficiency losses due to air leakage and acoustic damping, and require abrasive blade tips for effective sealing, leading to reduced efficiency and potential damage.
Innovation Solution
An abradable seal with small pores (1-10 microns) formed using MCrAlY alloy and a fugitive filler, which reduces air leakage and wear on compressor blades, improving aerodynamic efficiency and preventing damage by reflecting acoustic pressure waves and minimizing blade tip wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If large pores (400-1800 microns) are used in the abradable seal, then the seal material is easier to abrade and form, but air leakage increases causing aerodynamic efficiency losses
Solution Approach 1:
The patent changes the pore size parameter from large (400-1800 microns) to small (1-10 microns), transforming the seal from highly porous to micro-porous. This parameter change maintains abradability while dramatically reducing air leakage and improving aerodynamic efficiency by blocking airflow paths that caused energy losses.
Solution Approach 2:
The patent uses a composite material system comprising MCrAlY alloy combined with fugitive filler particles. This composite structure allows the seal to have both the abradability needed for forming and the micro-porous structure needed to prevent air leakage, resolving the contradiction between ease of manufacture and energy efficiency.
2Ease of manufacture
If large pores are used in the abradable seal, then the seal is easier to form, but acoustic damping effects increase causing additional aerodynamic losses
Solution Approach 1:
By changing the pore size parameter to 1-10 microns, the patent eliminates the acoustic damping effects caused by large pores. The small pore size prevents the pressure fluctuations and airflow instabilities that generate harmful acoustic damping, while still allowing the seal to form properly through abradability.
3Loss of energy
If hard and dense material is used to fill porosity and increase efficiency, then aerodynamic efficiency improves, but blade tip wear increases requiring hard or abrasive materials
Solution Approach 1:
Instead of using hard dense material, the patent changes the pore size parameter to micro-scale (1-10 microns). This creates a seal that is sufficiently dense to prevent air leakage and improve efficiency, yet the micro-porous structure combined with MCrAlY alloy provides controlled abradability that reduces blade tip wear compared to hard dense materials.
Solution Approach 2:
The patent uses controlled micro-porous materials rather than dense hard materials. The MCrAlY alloy with 1-10 micron pores provides a balance between density for efficiency and controlled porosity for reduced wear, allowing the seal to be abraded smoothly without requiring hard blade tip materials.
4Loss of energy
If the gap at blade tips is set very small to minimize leakage, then aerodynamic efficiency improves, but blade tips engage and rub against the seal causing potential damage
Solution Approach 1:
The patent changes the pore size parameter to micro-scale (1-10 microns), which allows the seal to maintain effectiveness at smaller blade tip gaps. The micro-porous structure prevents air leakage even when the gap is minimized, while the MCrAlY alloy provides controlled abradability that protects blade tips from damage by allowing smooth rubbing without severe wear.
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 seal significantly reduces aerodynamic losses and oil leakage, maintaining efficiency while preventing damage to compressor blades through optimized surface smoothing and erosion resistance.
Implementation Method 1
The outer air seal 36 provides improved aerodynamic efficiency and a lower density by including small pores within the microstructure of the outer air seal 36
Implementation Method 2
The abradability of the seal material prevents damage to the blades while the seal material itself wears to generate an optimized mating surface and thus reduce the leakage of air
Implementation Method 3
improving aerodynamic efficiency and preventing damage by reflecting acoustic pressure waves
Implementation Method 4
The outer air seal 36 is formed of MCrAlY
Data Source
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AI summary
An abradable seal (36) for a gas turbine engine includes a metal alloy and a plurality of pores in the metal alloy. The plurality of pores have a diameter of approximately 1 to 10 microns.