One-Piece CMC Turbine Ring Assembly with Deformable Tabs
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Solution Overview
Problem
The assembly of turbine rings made from ceramic matrix composite (CMC) materials in gas turbines is complex due to differences in expansion coefficients between CMC and metal components, leading to leakage issues and increased cooling requirements.
Innovation Solution
A simplified assembly using a complete one-piece CMC ring supported by non-segmented metallic annular supports with elastically deformable tabs or frustoconical surfaces for centering and locking, minimizing leakage and allowing differential expansion, and incorporating a layer of abradable material for reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a complete one-piece CMC ring is used, then assembly complexity is reduced and leakage is minimized, but differential expansion between CMC and metal supports must be accommodated
Solution Approach 1:
The patent changes the physical parameters of the support structure by introducing elastically deformable tabs that can change their deformation state based on thermal conditions. These tabs are designed with specific elastic properties allowing them to deform radially to accommodate differential expansion between the CMC ring and metal supports while maintaining structural integrity and simple assembly.
Solution Approach 2:
The support structure incorporates dynamic elements - the elastically deformable tabs can change their configuration from a restrained state during assembly to a deformed state during thermal operation. This dynamic adaptation allows the structure to respond to thermal expansion differences without requiring complex segmented designs, thus reducing assembly complexity while accommodating expansion.
2Manufacturing precision
If elastically deformable tabs are used for centering, then centering precision is improved, but the structure complexity increases
Solution Approach 1:
The elastically deformable tabs are designed to automatically center the CMC ring through their own elastic deformation properties. When the tabs deform radially under thermal load, they naturally maintain the ring in a centered position relative to the metal supports. This self-centering mechanism eliminates the need for additional complex centering devices or adjustment mechanisms, achieving precision without proportional complexity increase.
3Reliability
If a layer of abradable material is applied to the CMC ring, then blade tip contact resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies a layer of abradable material (such as ceramic or metal coating) onto the CMC ring surface. This creates a composite structure where the CMC provides structural integrity and thermal resistance, while the abradable layer provides controlled wear characteristics that protect blade tips during thermal expansion contact. The coating process is a standard manufacturing technique that adds minimal complexity while significantly improving reliability.
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 simplifies the assembly of CMC turbine rings, reduces gas leaks, and decreases cooling requirements by using a self-healing CMC material with a fibrous reinforcement and environmental barrier coating.
Implementation Method 1
The elastically deformable tabs can rest in recesses formed on the surface of the CMC ring, to help lock the CMC ring in rotation, and can extend in the circumferential direction
Implementation Method 2
the centering of the CMC ring is achieved by frustoconical bearing surfaces formed on the side faces of the CMC ring and the internal side faces of the metal annular supports
Implementation Method 3
Such a material has in fact mechanical properties making it suitable for constituting structural elements as well as the ability to retain these properties at high temperature, while having a density much lower than that of the metallic materials commonly used for such an application
Implementation Method 4
a turbine ring is provided on its inner face with a layer of abradable material with which the blade tips can come into contact without significant damage under the effect of dimensional variations of thermal origin or resulting centrifugal force
Data Source
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AI summary
The invention relates to a turbine ring assembly for a gas turbine, that comprises a full ring (10) made of a single piece and of a composite material having a ceramic matrix, a metal structure for holding the CMC ring including metal annular holders (20, 30) between which the CMC ring is provided while allowing for a differential expansion at least in the radial direction between the CMC ring and the annular holders, a means (40-42) for centring the CMC ring, and at least one member for rotatingly blocking the CMC ring about the axis thereof.