Turbine Combustor Insulating Member Attachment for Thermal Stress Relief
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Solution Overview
Problem
Existing attachment configurations in turbine engines with CMC insulating members result in reduced insulating performance due to heat transfer through metallic fasteners and relative motion between CMC and metallic components, leading to increased thermal stresses.
Innovation Solution
An attachment configuration that allows for relative motion between CMC insulating members and metallic structural members, using insulating materials to reduce heat transfer without metallic fasteners, maintaining functional thickness and thermal insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic fasteners are used to attach insulating members to structural members, then the attachment strength is improved, but heat transfer increases and insulating performance deteriorates
Solution Approach 1:
The patent introduces an insulating adhesive as an intermediary substance between the metallic structural member and the CMC insulating member. This adhesive layer serves as a thermal barrier that interrupts the heat conduction path through the attachment joint, thereby reducing heat transfer to the structural member while still providing mechanical attachment. The adhesive acts as a mediator that combines both attachment function and thermal insulation function.
Solution Approach 2:
The attachment system uses a composite approach by combining metallic fasteners or adhesives with insulating materials. The insulating adhesive creates a composite attachment joint that integrates both structural and thermal management functions, allowing the system to achieve both strong attachment and reduced heat transfer simultaneously.
2Stability of the object's composition
If CMC insulating members are rigidly attached to metallic structural members, then attachment stability is improved, but thermal stresses increase due to differential thermal expansion
Solution Approach 1:
The patent employs a compliant or flexible adhesive layer that can dynamically accommodate the differential thermal expansion between CMC and metallic components. The adhesive layer has viscoelastic properties that allow it to deform and relax thermal stresses while maintaining the attachment connection, transforming the rigid attachment into a more dynamic, stress-absorbing joint.
Solution Approach 2:
The insulating adhesive changes its mechanical parameters (such as modulus of elasticity, viscosity) with temperature to accommodate thermal expansion differences. The adhesive becomes more compliant at elevated temperatures, allowing for thermal movement while maintaining attachment stability, thus reducing thermal stress accumulation.
3Device complexity
If the functional thickness of insulating members is reduced to simplify attachment, then device complexity is reduced, but thermal insulation performance deteriorates
Solution Approach 1:
The insulating adhesive performs multiple functions simultaneously: it provides mechanical attachment, acts as a thermal barrier to reduce heat transfer, and accommodates thermal expansion differences. This multi-functionality eliminates the need for separate attachment components that would reduce the functional thickness of the insulating member, thereby maintaining insulation performance while simplifying the overall attachment system.
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
Enhances thermal insulation performance by minimizing heat transfer and reducing thermal stresses, while allowing for differential thermal expansion, thus maintaining efficient operation of turbine engine components.
Implementation Method 1
an insulating member, at least in part defining the combustion chamber, having a functional thickness, and fastened to the at least one structural member without reduction in the functional thickness
Implementation Method 2
An attachment configuration that allows for relative motion between CMC insulating members and metallic structural members
Data Source
AI summary
A combustor for a turbine engine includes a combustion chamber for combustion of fuel and air and the combustion of the fuel and air generates heat. A mixer assembly is disposed at a forward end of the combustor for receiving and mixing the fuel and the air and injecting the fuel and the air into the combustion chamber for the combustion. An insulating member is attached to at least one structural member and the insulating member defines the combustion chamber, at least in part. The insulating member has a functional thickness and is fastened to the at least one structural member without reduction in the functional thickness of the insulating member.