CMC Combustor Liner Attachment for Gas Turbine Engines
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Solution Overview
Problem
The challenge in gas turbine engines is securing ceramic matrix composite (CMC) heat shields to metallic shells without compromising their high-temperature capabilities, as metal fasteners can lose strength and melt at CMC operating temperatures, undermining the desired temperature performance.
Innovation Solution
A combustor design featuring a metallic shell with CMC heat shields and liners, where the liners are segmented and integral with the heat shields, supported by rings to prevent radial movement and allow for thermal growth, and a manufacturing method involving ceramic matrix composite preforms infiltrated with ceramic material to form the heat shields and liners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal fasteners are used to secure CMC heat shields to the metallic shell, then the heat shields can be properly mounted and retained, but the fasteners lose strength and may melt at CMC operating temperatures, undermining the high-temperature capability
Solution Approach 1:
The patent removes the metal fastener from the assembly entirely and replaces it with an integrated CMC attachment feature that is part of the heat shield itself. This extraction eliminates the material incompatibility issue while maintaining the retention function.
Solution Approach 2:
The attachment feature is merged with the heat shield as an integral component, both made from CMC materials. This merging ensures thermal compatibility and eliminates the strength-loss problem at high temperatures while maintaining secure attachment to the metallic shell.
2Strength
If cooling is applied to metal fasteners and surrounding areas to maintain their strength, then the fasteners can retain their structural integrity, but the desired high temperature capability and temperature uniformity of the CMC is compromised
Solution Approach 1:
The patent extracts the metal fastener from the high-temperature CMC environment entirely. By replacing it with an CMC-integrated attachment feature, no cooling is needed to maintain strength, and temperature uniformity across the CMC components is preserved.
3Stability of the object's composition
If segmented liner tiles are used with the heat shield, then thermal growth and manufacturing flexibility are improved, but additional components and assembly complexity are introduced
Solution Approach 1:
The combustor liner is segmented into multiple liner tiles that can independently accommodate thermal growth. Each tile is a separate component that can expand and contract freely, preventing stress buildup while maintaining liner integrity at high temperatures.
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 configuration enhances the high-temperature capability of CMC components, reduces cooling needs, and minimizes undesirable emissions by maintaining structural integrity and temperature uniformity within the combustor.
Implementation Method 1
heat shields made from ceramic matrix composite materials... CMCs may comprise ceramic fibers embedded in a ceramic matrix... The matrix and fibers can include any ceramic material
Implementation Method 2
allow for thermal growth
Data Source
AI summary
A combustor adapted for use in a gas turbine engine includes a combustor shell comprising metallic materials. The combustor shell is formed to define an internal space. The combustor further includes a heat shield mounted to an axially aft surface of the combustor shell within the internal space and a combustor liner arranged to extend along inner surfaces of the combustor shell within the internal space. The combustor liner cooperates with the heat shield to define a combustor chamber.