Sectorised CMC Gas Turbine Combustor Walls
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Solution Overview
Problem
The production of annular combustion chamber walls for gas turbines using ceramic matrix composite materials (CMCs) faces challenges in tool complexity, space optimization during densification, and differential thermal expansion issues between metal and CMC components, leading to increased manufacturing costs and assembly complexities.
Innovation Solution
The combustion chamber walls are divided into circumferentially segmented sectors that fold outward to form U-sections, connected to metal casings via elastically deformable elements, allowing for flexible assembly and thermal expansion compensation, with connecting elements arranged in gaps to be cooled by air flow and sealed with fibrous structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the combustion chamber walls are produced as a single complex annular structure, then the structural integrity is maintained, but the manufacturing complexity and tool requirements increase significantly
Solution Approach 1:
The combustion chamber walls are divided into multiple linear ceramic panels instead of being produced as a single complex annular structure. Each panel can be manufactured separately using simpler linear tools, then assembled to form the complete annular wall. This segmentation reduces manufacturing complexity while maintaining structural integrity through proper joining of panels.
2Productivity
If the preforms occupy the maximum space in the densification furnace, then the furnace loading is optimized, but the flexibility for tool design and preform arrangement is reduced
Solution Approach 1:
The combustion chamber walls are divided into multiple linear preforms that can be arranged flexibly within the densification furnace. This segmentation allows optimized space utilization while providing flexibility in tool design and preform arrangement. The linear preforms can be positioned to maximize furnace loading efficiency while accommodating various tool configurations.
3Stability of the object's composition
If rigid connecting elements are used to support the ceramic tiles, then the structural stability is improved, but the ability to accommodate differential thermal expansion between metal and ceramic components is lost
Solution Approach 1:
Flexible connecting elements are used to support the linear ceramic panels instead of rigid connections. These flexible elements can accommodate differential thermal expansion between the metal casings and ceramic panels while maintaining structural stability. The flexibility allows the assembly to adapt to thermal stresses without compromising the integrity of the combustion chamber.
4Reliability
If additional casing is added to provide sealing, then the sealing effectiveness is improved, but the assembly complexity and device volume increase
Solution Approach 1:
The sealing function is integrated into the existing connecting elements that attach the ceramic panels to the metal casings, rather than requiring a separate additional casing. This merging of sealing and structural functions maintains effective sealing while reducing assembly complexity and minimizing device volume.
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 approach reduces manufacturing costs, effectively absorbs thermal expansion differences, and optimizes the assembly process by simplifying the shape complexity and tooling requirements, while maintaining efficient thermal management through air cooling of the connecting elements.
Implementation Method 1
elastically deformable, which make it possible to absorb the differences in dimensional variations of thermal origin between metal parts and CMC parts
Implementation Method 2
The connecting elements are arranged in the gap between the chamber walls and the metal casings where they are cooled by the air flow bypassing the chamber
Implementation Method 3
The gaseous route is chemical infiltration in the gaseous phase or CVI ('Chemical Vapor Infiltration') which consists in placing the preform in an oven into which is introduced a reaction gaseous phase which diffuses within the preform and, under predetermined conditions in particular temperature and pressure, forms a solid ceramic deposit on the fibers by decomposition of a ceramic precursor contained in the gaseous phase
Implementation Method 4
The liquid route consists in impregnating the preform with a liquid composition containing a precursor of the ceramic matrix to be produced, the precursor typically being a resin in solution, then in carrying out a pyrolysis heat treatment after crosslinking
Data Source
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AI summary
The assembly has an annular combustion chamber with a chamber base (30) connected to annular internal and external walls (10, 20) made of ceramic matrix composite material. The walls are circumferentially divided into adjacent sectors (100, 200) along longitudinal edges. The sectors are folded towards the exterior of the chamber at the edges to form U-sectioned parts terminated by returns (102, 202) spaced from outer surfaces of the walls, respectively. Elastically deformable connection elements in the form of omega shaped bridges, are connected to the walls by fixation on the returns.