Patterned Abradable Seal Ridges for Gas Turbine Leakage
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Solution Overview
Problem
Current abradable seal systems in turbomachines face challenges in optimizing blade tip/seal clearance, leading to air leakage, excessive wear, material transfer, and heat generation, which complicates the design and requires expensive blade tipping processes to maintain efficiency.
Innovation Solution
A turbomachine sealing component with a patterned abradable/abrasive layer featuring discrete or continuous ridges, formed in the bondcoat or additional layer, which includes metallic alloys, intermetallics, or ceramic materials, and has varying thickness and porosity to effectively cut into blade tips, reducing the need for expensive blade tipping processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform abradable seal coating is used, then the seal provides continuous contact with the blade tip, but this leads to excessive wear, material transfer, and heat generation
Solution Approach 1:
The seal coating is segmented into discrete ridges separated by gaps, transforming the continuous contact interface into a discontinuous one. This segmentation allows the ridges to make selective contact with the blade tip, reducing overall wear and heat generation while maintaining sealing effectiveness through the concentrated contact points.
Solution Approach 2:
The seal coating exhibits local quality variations through different ridge heights, thicknesses, and material compositions within the same coating layer. This allows different regions of the seal to have tailored properties - some areas with higher abrasiveness for cutting into the blade, others with better wear resistance - thereby reducing harmful wear and heat effects while maintaining reliability.
2Manufacturing precision
If the abradable material is made softer to improve blade tip cutting, then sealing effectiveness improves, but excessive wear and material transfer increase
Solution Approach 1:
The seal coating uses composite materials combining abradable components (for blade tip cutting) with abrasive components (for wear resistance). This composite structure allows the softer abradable material to effectively cut the blade tip while the harder abrasive material prevents excessive wear and material transfer, resolving the contradiction between sealing effectiveness and material loss.
Solution Approach 2:
The material composition parameters are optimized by controlling the ratio and size of abrasive particles within the abradable matrix. By adjusting these parameters, the coating achieves the right balance of softness for blade cutting and hardness for wear resistance, thereby improving clearance control while reducing material transfer.
3Reliability
If expensive blade tipping processes are used to prevent wear, then blade durability improves, but manufacturing cost and complexity increase
Solution Approach 1:
The seal coating is designed to be self-servicing by automatically forming a protective interface with the blade tip through controlled wear of the ridges. As the ridges wear during operation, they self-adjust to maintain optimal contact and sealing while protecting the blade from excessive wear, eliminating the need for expensive periodic blade tipping processes.
Solution Approach 2:
The seal coating performs preliminary action by pre-forming the sealing interface and protective layer before the blade requires tipping. The abradable/abrasive coating progressively shapes the contact interface during initial operation, preventing the conditions that would later require expensive blade tipping interventions.
4Strength
If the seal coating is made more abrasive to reduce wear, then erosion resistance improves, but blade tip wear and heat generation increase
Solution Approach 1:
The seal coating applies partial action through discrete ridges rather than continuous contact. The ridges provide localized abrasive action for erosion resistance where needed, while the gaps between ridges reduce overall heat generation by limiting the contact area and allowing cooling airflow, thereby balancing erosion resistance with heat management.
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 patterned abradable/abrasive layer improves gas path sealing and durability by forming knife-edge like seals that preferentially wear select areas, reducing air leakage and eliminating the need for costly blade tipping processes, while maintaining structural integrity and thermal performance.
Implementation Method 1
The abradable material couples vary depending on location in the engine and typically must achieve a balance of properties such as abradability, erosion resistance, thermal properties
Implementation Method 2
U.S. Patent 8,017,240, to Strock, September 13, 2011, 'Ternary carbide and nitride thermal spray abradable seal material'
Data Source
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AI summary
A turbomachine sealing component has: a substrate having circumferential surface; and a coating on the circumferential surface. The coating or a layer thereof is patterned to form circumferential sealing ridges.