CMC Turbine Nozzle Abradable Ring Attachment
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Solution Overview
Problem
Attaching abradable material to turbine nozzles and compressor diffusers made of ceramic matrix composite (CMC) materials poses challenges due to differential thermal expansions and dimensional variations.
Innovation Solution
A metal abradable material support ring is designed with upstream and downstream attachment tabs and hooks that engage with the CMC nozzle or diffuser sectors, allowing for elastic deformation and sliding contact to accommodate thermal variations, ensuring proper centering and support without fastening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the abradable material support ring is fastened to the CMC nozzle sectors, then the attachment is secure and stable, but the differential thermal expansions between metal and CMC materials cause mechanical stress and potential damage
Solution Approach 1:
The attachment system transitions from a static fastened connection to a dynamic engagement where the metal support ring sectors can move relative to the CMC nozzle sectors. The hooks engage with the attachment tabs to provide stability while allowing differential thermal expansion through controlled movement and elastic deformation, preventing mechanical stress accumulation.
Solution Approach 2:
The engagement geometry between hooks and attachment tabs is designed to accommodate parameter changes during thermal cycling. The V-shaped profile and elastic deformation capacity allow the system to adapt to dimensional variations caused by temperature changes, maintaining attachment stability without generating excessive mechanical stress.
2Ease of manufacture
If the abradable material support ring is made of metal sectors with attachment tabs, then the attachment to CMC nozzles is simplified, but the differential thermal expansion between metal and CMC materials causes dimensional variations
Solution Approach 1:
The attachment tabs and hooks are designed with dynamic engagement characteristics that accommodate dimensional variations. The elastic deformation capacity of the engagement surfaces allows the system to absorb thermal expansion differences while maintaining proper alignment and centering, ensuring functional precision despite manufacturing and thermal dimensional changes.
Solution Approach 2:
The engagement surfaces between attachment tabs and hooks act as intermediaries that mediate the dimensional variations caused by differential thermal expansion. The V-shaped profile and elastic deformation capability of these engagement surfaces allow controlled movement while maintaining proper positioning, reconciling the simplicity of metal attachment with the need for dimensional consistency.
3Adaptability or versatility
If the engagement surfaces have elastic deformation capacity, then thermal dimensional variations are accommodated, but the attachment strength is reduced compared to fastened connections
Solution Approach 1:
The engagement system utilizes dynamic elastic deformation of the attachment tabs and hooks to accommodate thermal dimensional variations. This dynamic capability provides thermal adaptability while maintaining sufficient attachment strength through the engagement geometry and material properties, achieving a balance between flexibility and strength without requiring fasteners.
4Reliability
If the abradable material support ring is centered and aligned with the CMC nozzle, then the sealing performance is improved, but the alignment must accommodate thermal expansions without fastening
Solution Approach 1:
The alignment mechanism utilizes dynamic engagement between the V-shaped attachment tabs and hooks, allowing the metal support ring to self-center and align with the CMC nozzle while accommodating thermal expansions. The elastic deformation capacity of the engagement surfaces provides automatic alignment adjustment, maintaining sealing performance without complex alignment mechanisms or fastening systems.
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
This solution enables effective attachment and alignment of the abradable material support ring with CMC turbine nozzles and compressor diffusers, accommodating thermal expansions and maintaining sealing integrity while reducing mechanical stress.
Implementation Method 1
the contact is between portions in the form of hooks and tabs that therefore present capacity for elastic deformation, thus making it possible to accommodate differential variations in dimensions that are of thermal origin
Implementation Method 2
Differential variations in dimensions in the radial direction and in the axial direction can thus be compensated by sliding along the engagement surfaces
Data Source
AI summary
A turbine nozzle or a compressor diffuser includes sectors made of CMC material, each having an inner platform, an outer platform, and airfoils. An abradable material support ring is made up of sectors, each presenting upstream and downstream attachment tabs. Each inner platform presents on the inside an upstream hook and a downstream hook, and the abradable material support ring is supported by the nozzle or the diffuser by mutually engaging without fastening together firstly the end portions of the upstream attachment tabs and the upstream hooks and secondly the end portions of the downstream attachment tabs and the downstream hooks.