Combustion Chamber Subassembly for Steel-CMC Expansion Mismatch
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Solution Overview
Problem
The expansion coefficient mismatch between steel and Ceramic Matrix Composite (CMC) materials in turbomachine combustion chamber components leads to relative movement and leakage in their connection.
Innovation Solution
A turbomachine subassembly design featuring clamping lugs on a structural element made of steel that cooperate with a CMC component to maintain axial support and gas tightness, utilizing a radial rib with alternating hollows and solids to accommodate differential expansion, allowing for axial and rotational assembly adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel and CMC components are sealed together to form a combustion chamber, then the structural integrity and temperature resistance are improved, but the different coefficients of thermal expansion cause relative displacement and break the seal
Solution Approach 1:
The patent employs flexible lip seals positioned within grooves on the radial walls of the CMC component. These lip seals are made of elastomeric material that can deform and maintain contact with the steel component's sealing surface, compensating for relative displacement caused by differential thermal expansion while preserving seal integrity
Solution Approach 2:
The invention introduces flexible flanges as intermediary elements between the steel and CMC components. These flanges act as a buffer zone that absorbs the dimensional changes from thermal expansion differences, allowing the rigid steel and CMC parts to remain connected without direct sealing contact that would fail under differential movement
2Reliability
If flexible flanges and lip seals are introduced to compensate for thermal expansion differences, then the seal tightness is maintained, but the device complexity increases
Solution Approach 1:
The patent integrates the sealing function directly into the radial wall structure of the CMC component by incorporating grooves that house the lip seals. This merging of structural and sealing functions eliminates the need for separate sealing assemblies, reducing overall complexity while maintaining reliability
Solution Approach 2:
The lip seals are designed to automatically compensate for thermal expansion differences through their inherent elasticity. The seals self-adjust their position and contact pressure in response to dimensional changes, eliminating the need for external adjustment mechanisms or complex control 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 design effectively maintains a watertight connection between steel and CMC components despite their differing expansion coefficients, ensuring reliable operation under high-temperature conditions.
Implementation Method 1
the two components are made of materials having different coefficients of expansion
Implementation Method 2
the clamping lugs are elastically deformed along the axial direction by cooperation with the radial rib
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a turbomachine subassembly comprising a first component (10) forming a portion of a wall of a combustion chamber of the turbomachine and a second component (12) forming a connecting member connecting the first component (10) to a structural element of the combustion chamber, wherein the two components (10, 12) are made from materials having different coefficients of expansion, and wherein the two components (10, 12) are elements of revolution coaxial with a main axis A of the subassembly, and each comprising an annular radial wall (16, 24), the radial walls (16, 24) facing one another and bearing against one another axially in a first direction, characterized in that the second component (12) comprises a plurality of clamping tabs (28), with the clamping tabs (28) collaborating with the first component (10) in order to produce an axial force causing the radial walls (16, 24) to bear against one another.