Variable Vane Case Flowpath Repair With Plasma Coating
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Solution Overview
Problem
Gas turbine engines experience wear on the flow path surfaces due to the rotation of variable stator vanes, leading to efficiency loss, increased drag, and misalignment of vanes, necessitating a repair method to restore the design dimensions of the flow path surface.
Innovation Solution
A method involving measuring wear depth, machining to remove lips from wear recesses, and applying a nickel-aluminum plasma coating using a double-wire feed and plasma arc additive manufacturing process to restore the flow path surface to its original dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable stator vanes rotate to optimize compressor operability, then compressor efficiency is improved, but wear to the flow path surface of the case increases
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical properties of the flow path surface through plasma coating. A nickel-aluminum alloy coating is deposited onto the worn flow path surface, changing its material composition, hardness, and wear resistance properties. This allows the surface to withstand continued vane rotation and compression operations without further wear, thereby maintaining compressor efficiency over extended service intervals.
2Manufacturing precision
If wear recesses are formed in the flow path surface, then vane alignment becomes misaligned, but restoring the surface requires complex repair procedures
Solution Approach 1:
The patent replaces complex mechanical repair procedures with a plasma coating process. Instead of mechanically removing wear recesses and re-machining the flow path surface to restore original dimensions, the invention uses plasma arc additive manufacturing to deposit material that fills the wear recesses. This substitution of mechanical removal with thermal deposition simplifies the repair process while achieving the same alignment restoration goal.
Solution Approach 2:
The patent applies preliminary action by measuring the wear depth at multiple locations before applying the coating. This pre-assessment allows the coating thickness to be precisely controlled to match the wear profile, ensuring that the restored surface is substantially coplanar with the surrounding flow path surface. The preliminary measurement and planning eliminate the need for extensive post-repair machining or alignment adjustments.
3Loss of energy
If coating is applied to wear recesses to restore flow path surface, then drag is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements feedback control in the plasma coating process by continuously monitoring the coating thickness during deposition. The system uses the previously measured wear depth data to adjust coating parameters in real-time, ensuring that the deposited material precisely fills the wear recesses without creating excessive buildup or thin spots. This feedback mechanism maintains the required manufacturing precision while achieving drag reduction through proper surface restoration.
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 method effectively repairs the flow path surface, reducing drag, improving efficiency, and preventing further wear by ensuring optimal vane alignment and reducing frictional loads on the actuation system.
Implementation Method 1
applying a coating to the wear recess using a double-wire feed and plasma arc additive manufacturing process
Implementation Method 2
applying a coating to the wear recess using a double-wire feed and plasma arc additive manufacturing process
Data Source
AI summary
A method for repairing a flow path surface of a case for a variable vane assembly includes measuring a wear depth at a location within a wear recess formed in the flow path surface of the case, determining a coating thickness corresponding to the wear depth at the location, and repairing the flow path surface of the case by applying a coating to the wear recess, where the coating has the coating thickness at the location.