Integrally Cast CMC Combustor Dome and Liner for Gas Turbine
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Solution Overview
Problem
Gas turbine engines face challenges in accommodating the mechanical properties of ceramic matrix composite (CMC) materials, particularly due to differences in thermal expansion coefficients between CMC and metal materials, leading to complex attachment assemblies that disrupt aerodynamics in combustion chambers.
Innovation Solution
A combustor assembly with a combustor dome and combustion chamber liners formed integrally of CMC materials, extending continuously along the circumferential direction, and featuring transition portions to ensure seamless integration and uniform thermal expansion, along with a bolted attachment for the inner liner, enhancing aerodynamic flow and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are used for combustion chamber liners, then high temperature resistance is improved, but thermal expansion mismatch with metal dome causes attachment complexity
Solution Approach 1:
The patent merges the inner liner and outer liner into a single integrated CMC combustion chamber assembly that attaches to the metal dome as one unit. This integration eliminates the need for separate attachment mechanisms for multiple components, reducing overall attachment complexity while maintaining the high temperature resistance benefits of CMC materials.
Solution Approach 2:
The patent introduces a transition section as an intermediary component between the CMC combustion chamber and the metal dome. This transition section accommodates the thermal expansion mismatch by providing a gradual geometry change and material transition zone, simplifying the attachment process while managing the differential thermal expansion between CMC and metal materials.
2Strength
If complex attachment assemblies are used to join CMC liners to metal dome, then structural integrity is improved, but aerodynamic flow is disrupted
Solution Approach 1:
The patent applies local quality by concentrating the attachment features only at the dome interface where structural connection is needed, while maintaining a smooth, seamless interior surface throughout the combustion chamber. The transition section provides localized geometry changes for attachment purposes without affecting the overall aerodynamic flow path, thus preserving airflow quality while ensuring structural integrity.
Solution Approach 2:
The patent resolves the conflict between attachment complexity and aerodynamic flow by moving attachment features to the exterior dome interface rather than introducing internal structures into the flow path. The transition section manages thermal expansion in the radial and axial dimensions without creating flow-disrupting features in the circumferential flow direction.
3Object-generated harmful factors
If seamless CMC structure is used, then aerodynamic flow is improved, but thermal expansion management becomes challenging
Solution Approach 1:
The patent segments the thermal expansion management function into a dedicated transition section that is geometrically distinct from the main combustion chamber. This transition section handles the thermal expansion accommodation between CMC and metal materials, while the main combustion chamber maintains its seamless structure for optimal aerodynamic flow. The segmentation allows independent optimization of each function.
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 improves aerodynamic flow and thermal management within the combustion chamber by eliminating seams and allowing uniform thermal expansion, reducing pressure drops and enhancing cooling efficiency, while maintaining structural integrity and aerodynamic performance.
Implementation Method 1
CMC materials have different coefficients of thermal expansion than the traditional metal materials. Therefore, the attachment of the inner and outer liners, formed of a CMC material, to the dome, formed of a metal material, may require a fairly complicated attachment assembly.
Data Source
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AI summary
A combustor assembly (100) for a gas turbine engine includes a combustor dome (102) and a combustion chamber liner (104, 106) formed integrally of a ceramic matrix composite (CMC) material. The combustor dome (102) defines a plurality of openings (154) for receiving a respective plurality of fuel air injector hardware assemblies (156) and may extend continuously along a circumferential direction (C).