CMC Component Cooling Cavities Green Machining
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Solution Overview
Problem
Ceramic matrix composite (CMC) components in gas turbine engines face challenges in forming complex cooling geometries and require effective cooling features to mitigate the effects of high combustion gas temperatures, which traditional methods struggle to address due to their lower thermal conductivity and intricate geometry requirements.
Innovation Solution
The development of a component with a core and outer enclosure that defines cooling cavities on the exterior surface, fluidly coupled to an air supply, and featuring film holes and cross-over holes for efficient cooling, where the cooling cavities are green machined in a green state to allow for more complex geometries and the use of filler materials to secure the cavities during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are used for turbine components to withstand extreme temperatures, then temperature resistance is improved, but thermal conductivity decreases requiring closer cooling features to the airfoil surface
Solution Approach 1:
The patent performs preliminary action by forming cooling cavities and conduits in the green state (uncured) CMC preform before final curing. This allows complex cooling geometries to be easily shaped and positioned close to the airfoil surface without the difficulty of machining cured ceramic materials, thereby achieving precise cooling feature placement while maintaining the temperature resistance benefits of CMC materials
Solution Approach 2:
The patent applies parameter changes by utilizing the different physical state of CMC materials during manufacturing. The green state preform has different mechanical properties (softer, more formable) compared to the cured state, allowing complex cooling cavities to be formed with high precision. After curing, the material achieves its final temperature resistance properties while retaining the precisely formed cooling features
2Reliability
If cooling cavities with complex geometry are formed in CMC components, then cooling effectiveness is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent performs preliminary action by forming complex cooling cavities and conduits in the green state CMC preform before final curing. This preliminary forming allows intricate geometries to be easily shaped using conventional machining or molding techniques on the uncured material, avoiding the manufacturing difficulties of working with cured ceramic composites. The complex geometry is thus achieved with high manufacturing ease in the green state
Solution Approach 2:
The patent applies parameter changes by exploiting the transition from green state to cured state. In the green state, the CMC preform has softer, more formable properties that enable easy creation of complex cooling geometries. After curing, the material hardens to provide structural integrity while maintaining the complex cooling cavity geometry, thus achieving both cooling effectiveness and manufacturing ease
3Reliability
If cooling features are placed closer to the airfoil surface to compensate for lower thermal conductivity, then cooling effectiveness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent performs preliminary action by forming cooling cavities and conduits in the green state CMC preform before final curing and assembly. This preliminary forming allows precise positioning of cooling features close to the airfoil surface to be achieved during the mold-making or machining stage, when the material is still formable. The precise positioning is thus accomplished with high manufacturing precision without the difficulty of machining cured materials
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 enables the formation of more complex cooling geometries, enhancing film cooling on the component's surface, reducing the need for internal conduits, and improving engine efficiency by minimizing the amount of compressed cool air required from the compressor section.
Implementation Method 1
cooling features for minimizing the effects of the relatively hot combustion gases, such as, e.g., film holes, cooling holes, or slots, that may provide cooling within and/or over the surface of the airfoils
Data Source
AI summary
A component for a gas turbine engine including a core and an outer enclosure. The core includes an exterior surface extending along a length between a first end and a second end and at least partially defines a cooling cavity on the exterior surface extending from the first end along at least a portion of the length. The cooling cavity is fluidly coupled to an air supply at the first end. The outer enclosure includes an outer surface. The outer enclosure is positioned outside the core and extends from the first end of the core along at least a portion of the length of the core and at least partially defines the cooling cavity.