Combustion Chamber Subassembly for Differential Thermal Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The differing coefficients of expansion between steel and Ceramic Matrix Composite (CMC) materials in turbomachine combustion chamber components lead to relative movement and loss of tightness in their connection, posing a challenge for maintaining a secure bond.
Innovation Solution
The use of axisymmetric components with clamping tabs that apply axial force to maintain contact between radial walls, including a radial rib with alternating recesses and solid portions, allows for elastic deformation and stable axial and rotational assembly, ensuring a tight connection despite material expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel and CMC components are connected directly to maintain structural integrity, then strength is improved, but relative movement occurs due to different expansion coefficients causing loss of tightness
Solution Approach 1:
The patent employs flexible sealing elements (gaskets or seals) positioned between the steel and CMC components. These flexible elements can accommodate the differential thermal expansion between the two materials while maintaining the sealing function, thus preserving both connection strength and tightness reliability under thermal cycling conditions.
2Reliability
If flexible flanges and lip seals are inserted to compensate for relative movement, then tightness is improved, but device complexity increases
Solution Approach 1:
Instead of making the entire connection structure flexible or complex, the patent applies flexibility only at the specific sealing interface where differential expansion occurs. The rigid structural portions remain simple and strong, while a localized flexible sealing element handles the thermal expansion compensation, thus maintaining reliability without significantly increasing overall device complexity.
3Reliability
If clamping tabs are used to apply axial force pressing radial walls together, then tightness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The clamping tabs are designed with elastic deformation capability, allowing them to dynamically adjust the clamping force as thermal expansion occurs. This dynamic adaptation compensates for dimensional variations and assembly tolerances, maintaining reliable tightness without requiring extremely high manufacturing precision. The elastic tabs absorb dimensional variations through their compliance.
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 effectively maintains the axial bearing of radial walls against each other, ensuring a secure and stable connection between steel and CMC components, even with varying expansion rates, thereby maintaining the integrity of the turbomachine's combustion chamber.
Implementation Method 1
the clamping tabs are elastically deformed according to the axial direction by cooperation with the radial rib
Implementation Method 2
a cooling air flow passes through these walls and the material of the walls has been adapted so that at least one portion thereof are made of a material known as CMC
Data Source
AI summary
A turbomachine subassembly including a first component forming a portion of a wall of a combustion chamber of the turbomachine and a second component forming a connecting member connecting the first component to a structural element of the combustion chamber, wherein the two components are made from materials having different coefficients of expansion, and wherein the two components are elements of revolution coaxial with a main axis A of the subassembly, and each including an annular radial wall, the radial walls facing one another and bearing against one another axially in a first direction, wherein the second component includes a plurality of clamping tabs, with the clamping tabs collaborating with the first component in order to produce an axial force causing the radial walls to bear against one another.