CMC Heat Shield Interference Fit for Gas Turbine Bulkhead
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Solution Overview
Problem
Existing gas turbine engine combustor bulkheads face issues with heat-resistant coatings oxidizing and shortening the combustor's lifespan due to extreme temperatures, and traditional fasteners can weaken ceramic matrix composite (CMC) heat shields by introducing faults during assembly.
Innovation Solution
A combustor design featuring a ceramic matrix composite (CMC) heat shield panel with an interference fit to a metallic bulkhead panel, eliminating the need for fasteners and utilizing a high heat tolerance machinable material like silicon to enhance durability, along with a bulb-shaped interference fit feature for secure positioning and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fasteners are used to attach the heat shield to the bulkhead, then the heat shield can be securely positioned, but the fasteners introduce faults that weaken the CMC material and reduce reliability
Solution Approach 1:
The patent removes fasteners entirely from the heat shield attachment system. Instead of using mechanical fasteners to secure the heat shield to the bulkhead, the design relies on an interference fit between the heat shield and bulkhead surfaces, eliminating the source of faults that fasteners introduce to the CMC material.
Solution Approach 2:
The patent replaces the mechanical fastening system with a friction-based interference fit system. The heat shield is secured through contact pressure and friction between mating surfaces rather than through mechanical fasteners, substituting a mechanical connection system with a surface-contact-based system that avoids introducing faults into the CMC.
2Temperature
If metallic bulkhead panels are coated with heat resistant coating, then resistance to extreme temperatures is improved, but the coating oxidizes under extreme heat conditions and shortens combustor lifespan
Solution Approach 1:
The patent employs a composite structure consisting of a metallic bulkhead panel combined with a CMC heat shield. The CMC material provides superior heat resistance without the oxidation problems that affect metallic coatings under extreme temperature conditions, extending the combustor's operational lifespan.
Solution Approach 2:
The patent applies heat shield protection specifically to the bulkhead panel areas exposed to extreme combustion temperatures. The CMC heat shield is positioned to provide localized thermal protection where it is most needed, rather than coating the entire bulkhead, allowing the metallic bulkhead to maintain its structural properties while the CMC handles the thermal exposure.
3Ease of manufacture
If the heat shield panel uses uniform thickness throughout, then manufacturing is simplified, but cooling efficiency and structural optimization are compromised
Solution Approach 1:
The patent implements variable thickness in the heat shield panel, with different axial thicknesses at different locations. The first axial thickness and second axial thickness are optimized for their respective positions to provide enhanced cooling efficiency and structural performance in high-heat zones while maintaining manufacturability through controlled variation rather than complete uniformity.
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 effectively protects the bulkhead from extreme temperatures, reduces the risk of heat shield failure, and extends the combustor's lifespan by maintaining the heat shield's integrity without the weaknesses introduced by traditional fasteners, while providing a cooling effect through airflow.
Implementation Method 1
at least one heat shield panel interior to the combustor region, the at least one heat shield panel is connected to the bulkhead panel via an interference fit
Implementation Method 2
the at least one heat shield panel is connected to the bulkhead panel via an interference fit
Data Source
AI summary
A heat shield for a combustor includes a ring shaped body including a central opening defining a radially inner edge of the ring shaped body. The ring shaped body is at least partially made of a ceramic material. The heat shield includes a shaped portion designed to enhance an interference fit.