CMC Combustor Dome Tile Segmentation for Thermal Stress
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Solution Overview
Problem
In gas turbine engines, the use of ceramic matrix composite (CMC) components with metallic support structures leads to overheating and thermal stress due to mismatched thermal expansion coefficients, necessitating a solution to shield the metallic support and decouple CMC components from structural loads.
Innovation Solution
A combustor assembly featuring an annular CMC combustor dome formed from multiple tiles, positioned between the support structure and combustion chamber, which shields the metallic support from high temperatures and decouples the CMC dome from structural loads, using an annular frame and bracket system to secure the dome without direct mounting, thereby managing thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If CMC combustor dome is mounted directly to metallic support structure, then structural load path is continuous, but thermal stress increases due to CTE mismatch
Solution Approach 1:
The support structure is segmented into discrete mounting points (annular frame and brackets) rather than continuous attachment, creating isolation zones that break the thermal stress transmission path while maintaining structural support functionality
Solution Approach 2:
The metallic support structure acts as an intermediary element between the CMC dome and engine structure, with the frame and brackets serving as thermal decoupling intermediaries that allow mechanical support while minimizing thermal stress transfer through strategic positioning and geometry
2Strength
If metallic support structure is exposed to combustion chamber, then structural support is provided, but overheating occurs due to high combustion temperatures
Solution Approach 1:
The support structure is segmented into discrete components (annular frame and separate brackets) positioned at specific locations away from the combustion chamber, creating thermal zones that protect the metallic structure from direct exposure to high combustion temperatures while maintaining structural support
Solution Approach 2:
The support structure transitions from potential direct contact in the thermal field to positioning in a different spatial dimension (away from the combustion chamber), using the annular frame and brackets to provide support from a thermally protected zone
3Strength
If CMC combustor dome is formed as single piece, then structural integrity is high, but manufacturing and repair complexity increases
Solution Approach 1:
The CMC combustor dome is segmented into multiple tiles that can be manufactured separately using standard CMC fabrication processes, then assembled into a complete dome structure, reducing manufacturing complexity and enabling targeted repair of individual tiles without replacing the entire dome
4Ease of manufacture
If CMC combustor dome is formed as single piece, then manufacturing is simplified, but natural frequencies become unacceptable causing vibration
Solution Approach 1:
Segmenting the dome into multiple tiles introduces structural discontinuities that alter the natural frequencies of the dome assembly, moving them away from problematic resonance frequencies that would cause vibration, while still maintaining overall structural integrity through proper tile configuration and mounting
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 effectively reduces thermal stress on CMC components, allows higher combustion temperatures, and simplifies manufacturing and repair by segmenting the dome into tiles, enhancing structural integrity and reducing vibration.
Implementation Method 1
the CMC combustor dome shields a metallic support structure from a combustion chamber of the combustor assembly
Implementation Method 2
The first end of each tile of the plurality of tiles disposed within a groove of a frame channel of the annular frame
Data Source
AI summary
Combustor assemblies are provided. An exemplary combustor assembly comprises an annular ceramic matrix composite (CMC) inner liner including an inner liner flange, an annular CMC outer liner including an outer liner flange, and an annular CMC combustor dome comprising a plurality of tiles positioned circumferentially adjacent one another. Each tile has a first end radially opposite a second end. The CMC inner liner, outer liner, and combustor dome form a combustor, and the CMC combustor dome is positioned at a combustor forward end. The combustor assembly also comprises a support structure for supporting the combustor and including an annular frame having a frame channel defining a groove and an inner and outer support flanges. The first end of each tile is disposed within the frame channel groove. The inner liner flange is secured to the inner support flange and the outer liner flange is secured to the outer support flange.