Dual Wall Liner Shell Design for Gas Turbine Burn Through Tolerance
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Solution Overview
Problem
As gas turbine engines operate at higher firing temperatures to increase efficiency, the metal components, such as combustion shells and panels, face significant temperature extremes and degradation from oxidizing and corrosive environments, leading to challenges in maintaining optimal temperatures and preventing oxidation and corrosion.
Innovation Solution
A dual wall liner design for gas turbine engines featuring a shell with a thermal barrier coating (TBC) on one side and a metallic layer with enhanced oxidation resistance, where the TBC has lower thermal conductivity than the shell material, and includes heat transfer augmentation features like panel studs and holes to direct cooling air effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the firing temperature of the turbine is increased to improve efficiency, then the power output increases, but the metal temperature of combustion components increases leading to oxidation and corrosion degradation
Solution Approach 1:
A thermal barrier coating (TBC) is applied to the combustion shell to act as an intermediary layer between the hot gas path and the metal shell. The TBC has lower thermal conductivity than the shell material, reducing heat transfer to the metal and protecting it from oxidation and corrosion while allowing higher firing temperatures for improved power output
Solution Approach 2:
The combustion shell is designed with a composite structure consisting of a metallic layer and a thermal barrier coating layer. The metallic layer provides structural strength and oxidation resistance, while the TBC layer provides thermal insulation. This composite structure enables the shell to withstand higher temperatures without degradation
2Reliability
If a thermal barrier coating is applied to the combustion shell to protect from heat, then the oxidation resistance improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The oxidation resistance function is extracted and concentrated in a separate metallic layer that is applied to the shell surface. This metallic layer is at least twice as resistant to oxidation as the base shell material, providing enhanced protection without requiring complex multi-layer coating systems
Solution Approach 2:
The thermal barrier coating and metallic layer are combined into a single integrated coating system. The TBC is disposed over the metallic layer, creating a unified structure that provides both thermal insulation and oxidation resistance in one application process, reducing manufacturing complexity
3Temperature
If cooling air flow is directed to the shell surface to reduce metal temperature, then the temperature control improves, but the heat transfer efficiency decreases due to smooth surface geometry
Solution Approach 1:
Heat transfer augmentation features are applied locally to specific areas of the shell surface where cooling is most needed. These features include protrusions, recesses, or extended surfaces that increase the local surface area and disrupt the boundary layer, enhancing heat transfer from the hot gas path to the cooling air without requiring overall surface redesign
Solution Approach 2:
The heat transfer augmentation features utilize curved and irregular surface geometries instead of smooth flat surfaces. These curved features promote turbulence and improve convective heat transfer coefficients, allowing more effective cooling of the shell metal surface
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 dual wall liner design effectively protects the engine components from high temperatures and oxidation, extending their lifespan by managing heat transfer and corrosion, while maintaining efficiency and reducing weight and cost associated with thermal coatings.
Implementation Method 1
the TBC comprises a lower thermal conductivity than that of the shell material
Implementation Method 2
the metallic layer is at least twice as resistant to oxidation as the shell material
Data Source
AI summary
A dual wall liner for a gas turbine engine may comprise a shell having a first side and a second side, a panel contacting the shell, the panel at least partially defining a hot gas path through which a hot gas flows, wherein the first side of the shell faces the panel, wherein the shell includes a thermal barrier coating (TBC) disposed on the first side of the shell. The TBC may thermally protect the shell from heat from a hot gas path.