Compliant Blade Platform for CMC Turbine Blades
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Solution Overview
Problem
Existing approaches for retaining ceramic matrix composite (CMC) turbine blades in gas turbine engines face limitations, including weight-related stress issues due to centripetal forces and abrasive contact with metallic disks, which reduces operational life and increases maintenance costs.
Innovation Solution
A turbine wheel assembly with high-temperature metal or metal alloy blade platforms that provide a compliant interface between CMC turbine blades and a metallic rotatable disk, eliminating direct contact and incorporating dampers for vibration damping, while using high-temperature seals to minimize fluid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If CMC turbine blades are directly retained in metallic disk slots, then the blade weight is reduced, but the blades suffer from abrasive contact with the metallic disk reducing operational life
Solution Approach 1:
A metallic blade platform is introduced as an intermediary component between the CMC turbine blade and the metallic disk slot. The platform provides a compliant interface that prevents direct abrasive contact between the ceramic blade and metallic disk, while the lightweight CMC blade remains attached to the platform. This resolves the contradiction by maintaining blade weight reduction while eliminating abrasive wear through the mediating platform structure.
2Device complexity
If CMC turbine blades are directly retained in metallic disk slots, then the device complexity is reduced, but stress from centripetal forces increases due to lack of compliant interface
Solution Approach 1:
The blade platform incorporates compliant features including dampers and flexible mounting mechanisms that change the mechanical parameters of the retention system. These compliant elements allow the platform to absorb and dampen vibratory stresses induced by centripetal forces during turbine rotation, reducing stress transmission to the CMC blade while maintaining a relatively simple overall structure.
3Reliability
If a compliant interface with dampers is added to reduce vibration, then the operational life is extended, but the device complexity increases
Solution Approach 1:
The dampers, seals, and retention features are merged into an integrated blade platform assembly rather than being separate components. The platform combines multiple functions including vibration damping, sealing, and blade retention into a single structured component, which extends operational life through vibration reduction while minimizing the increase in overall device complexity through functional integration.
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 solution reduces stress and abrasive wear on CMC turbine blades, extending their operational life and lowering maintenance costs by providing a lightweight, compliant interface that minimizes contact stress and fluid leakage.
Implementation Method 1
The blade platform can include one or more dampers to facilitate dynamic damping of turbine blades during periods of high cycle frequency induced vibrations
Implementation Method 2
High temperature seals can also be utilized with the blade platforms to discourage fluid flow leakage from the fluid flow path through gaps between the blade platforms and the turbine blades
Data Source
AI summary
The present disclosure provides for a turbine wheel having a blade platform disposed to compliantly secure ceramic turbine blades to a rotatable disk. The platform includes opposing ends to engage a portion of an airfoil of each turbine blade and radial extensions to engage a portion of a root of each turbine blade.