Abrasive Coating for Gas Turbine Tip Clearance Control
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Solution Overview
Problem
High-temperature gas turbine engines face efficiency losses due to over-tip leakage between blade tips and the surrounding blade track, which existing sealing techniques fail to adequately address, especially under varying temperature conditions.
Innovation Solution
An abrasive coating system is applied to the tips of rotating components, comprising a barrier layer made of materials like hafnium oxide, hafnon, or rare earth silicates, combined with an abrasive material such as silicon carbide, which contacts an abradable layer on the stationary component to control tip clearance and reduce leakage, while maintaining thermomechanical stability and resistance to chemical exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static seal segments are used to seal between blade track and rotating blades, then tip clearance control is achieved, but manufacturing precision and reliability deteriorate under varying temperature conditions
Solution Approach 1:
The seal system transitions from static seal segments to a dynamic abrasive coating system on rotating blade tips. The abrasive coating actively adjusts to temperature variations and maintains optimal tip clearance through controlled abrasion of the abradable layer, providing both sealing reliability and manufacturing precision under varying operating conditions.
Solution Approach 2:
The invention changes the physical and chemical parameters of the sealing interface by applying an abrasive coating system with specific material properties (barrier layer + abrasive material) that responds to temperature changes. This allows the tip clearance to be dynamically controlled through controlled material removal rates, achieving both precision and reliability.
2Reliability
If abrasive coating system is applied to blade tips, then tip clearance control and leakage reduction are improved, but device complexity increases
Solution Approach 1:
The abrasive coating system uses composite materials consisting of a barrier layer (hafnium oxide, hafnon, or rare earth silicates) combined with abrasive material (silicon carbide, molybdenum disilicide, or silicon). This composite structure provides both protective barrier properties and abrasive functionality, achieving effective leakage control without excessive system complexity.
Solution Approach 2:
The abrasive coating system performs multiple functions simultaneously: it controls tip clearance, reduces leakage, protects the blade tip from mechanical and chemical stress, and maintains thermomechanical stability. This multi-functionality justifies the added complexity by delivering multiple performance benefits from a single coating application.
3Productivity
If abrasive coating system is applied to blade tips, then operational efficiency is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The abrasive coating system is designed to self-regulate and self-adjust during operation. The controlled abrasion of the abradable layer by the abrasive coating automatically maintains optimal tip clearance and leakage control without requiring precision manufacturing of the clearance gap itself. The system serves its own function of maintaining sealing effectiveness.
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 abrasive coating system effectively reduces airflow between blade tips and the blade track, enhancing the operational efficiency of gas turbine engines by minimizing clearance and protecting the underlying components from mechanical and chemical stress at high temperatures.
Implementation Method 1
the abrasive coating system contacts a portion of the abradable layer during at least part of a rotation of the gas turbine blade for at least some operating conditions so that the abrasive coating system abrades some of the abradable layer
Data Source
AI summary
A system may include a stationary component including: a substrate and an abradable layer on the substrate. The system also may include a rotating component including a tip and an abrasive coating system on the tip. The abrasive coating system may include a barrier layer and an abrasive material. The barrier layer may include at least one of hafnon, hafnium oxide, a blend of hafnium oxide and silicon or silicon oxide, a rare earth silicate, BSAS, stabilized zirconia, or stabilized hafnia. The blade track or blade shroud and the gas turbine blade are configured so the abrasive coating system contacts a portion of the abradable layer during rotation of the rotating component. The abradable layer is configured to be abraded by the contact by the abrasive coating system.