CMC Turbine Blade Damper Land for Smooth Vibration Transfer
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Solution Overview
Problem
Ceramic matrix composite (CMC) blades in gas turbine engines have poorer surface qualities due to undulations, residual porosity, and inherent roughness, which interfere with the smooth attachment of dampers, leading to inefficient vibratory force transfer.
Innovation Solution
A damper land with a smoother outward-facing surface, made of materials like rare earth silicates or yttria-stabilized zirconia, is applied to the CMC blade platform and machined to a surface roughness of less than 100 ra microinches, facilitating efficient damper attachment and vibratory force control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC blade material is used for high-temperature applications, then temperature resistance is improved, but surface quality deteriorates due to undulations, residual porosity, and inherent roughness
Solution Approach 1:
The patent applies a damper land coating specifically to the platform surface where the damper interfaces, rather than the entire blade. This localized treatment provides the smooth surface quality needed for damper attachment while maintaining the CMC material's high-temperature properties in the airfoil and other critical sections.
Solution Approach 2:
The patent creates a composite structure by applying a damper land coating (made of materials like mullite, hafnon, or zircon) over the CMC blade platform. This composite approach combines the high-temperature resistance of CMC with the smooth surface and machinability of the coating material.
2Reliability
If damper attachment is implemented on rough CMC surface, then vibratory force control is improved, but attachment efficiency deteriorates due to poor surface contact
Solution Approach 1:
The damper land coating is applied only to the specific platform area where damper attachment occurs, providing a locally optimized smooth surface that enhances attachment efficiency without affecting the overall blade structure or vibratory force control functionality.
Solution Approach 2:
The damper land coating acts as an intermediary layer between the rough CMC blade surface and the damper. This intermediate layer provides a machinable, smooth interface that improves contact and attachment while allowing the damper to function effectively for vibratory force control.
3Manufacturing precision
If damper land coating is applied to improve surface smoothness, then surface finish is improved, but device complexity increases due to additional manufacturing steps
Solution Approach 1:
The coating is applied only to the platform surface area required for damper attachment, minimizing the amount of material applied and reducing processing time and complexity compared to coating the entire blade.
Solution Approach 2:
The patent specifies target surface roughness parameters (Ra less than 100 microinches, preferably 20-100 microinches) to guide the coating and machining process, providing clear quantitative targets that simplify process control and inspection.
Data Source
AI summary
A gas turbine engine blade includes a platform; an airfoil section extending from the platform in a first direction; a mount extending from the platform in a second direction opposite the first direction; a damper land on the platform, the damper land having a relatively smoother outward-facing surface than the platform; and a damper interfacing with the outward-facing surface of the damper land. A method of making a gas turbine engine blade is also disclosed.