CMC Flange Cooling Cavities for Lower Thermal Stress
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Solution Overview
Problem
CMC components with flanges, such as blade outer air seals, face challenges in cooling due to increased material thickness under flanges, leading to higher thermal gradients and thermal stresses, which existing manufacturing methods fail to adequately address.
Innovation Solution
Incorporating cooling cavities beneath flanges during the layup or densification of CMC components, with dedicated cooling fluid inlet and outlet passages, to facilitate effective cooling and reduce thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If CMC components use flanges with increased material thickness for load bearing, then structural strength is improved, but thermal conductivity deteriorates leading to higher thermal gradients and stresses
Solution Approach 1:
The flange structure is segmented by introducing cooling cavities that divide the solid material into regions separated by cooling channels. This segmentation allows cooling fluid to flow through the flange, creating internal heat dissipation pathways that reduce thermal gradients while preserving the external load-bearing structure.
Solution Approach 2:
Cooling fluid is introduced as an intermediary substance that flows through the cavities within the flange structure. This fluid acts as a heat transfer medium, absorbing thermal energy from the thick flange regions and carrying it away, thereby reducing thermal gradients without compromising structural integrity.
2Temperature
If cooling cavities are introduced beneath flanges, then thermal gradient is reduced, but manufacturing complexity increases
Solution Approach 1:
The cooling cavities are formed during the preform layup stage before final densification. Tooling or sacrificial materials are positioned between plies to create cavity spaces, and these cavities are then sealed and integrated into the flange structure during subsequent processing steps, avoiding the need for post-manufacturing modifications.
Solution Approach 2:
The formation of cooling cavities is merged with the existing preform fabrication process. The same layup techniques and equipment used to create the CMC structure are also used to create the cooling cavities, combining two functions (structural formation and cooling system integration) into a single manufacturing workflow.
3Temperature
If cooling cavities are formed during layup using tooling or sacrificial material, then cooling effectiveness is improved, but manufacturing steps increase
Solution Approach 1:
Cooling cavities are formed during the preform layup stage before final densification. Tooling or sacrificial materials are positioned between plies to create cavity spaces, and these cavities are then sealed and integrated into the flange structure during subsequent processing steps.
Solution Approach 2:
The same preform fabrication equipment and processes used for creating the CMC structure are also used to create the cooling cavities. The layup process simultaneously forms both the structural plies and the cooling cavity spaces, making the manufacturing process multi-functional and avoiding dedicated separate operations.
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 implementation of cooling cavities and passages effectively reduces thermal gradients and stresses in CMC components with flanges, enhancing their operational lifespan and performance.
Implementation Method 1
The region beneath such flanges has an increased material thickness in comparison to other portions of the component. These greater thicknesses render cooling more difficult and result in the formation of higher thermal gradients which in turn result in higher through-thickness and in-plane thermal stresses.
Implementation Method 2
To increase their operational lifespans, precautions can be taken to cool CMC components by subjecting the components to a flow of cooling fluid (e.g., air).
Data Source
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AI summary
A method is described for introducing cooling cavities (180) into CMC components (100) beneath flanges (115, 116) such as T-shaped flanges (115, 116) within the CMC components (100). During layup, a base (110) of the CMC component (100) from a plurality of ceramic fiber plies (110a, 110b) in which a cooling cavity (180) is formed below the connection region between the flange (115, 116) and the base (110). Cooling fluid inlet passages (150, 160) are provided to permit cooling fluid to enter the cooling cavity (180) and thereby cool the internal region of the CMC component (100) to reduce formation of thermal stresses.