CMC Cooling Hole Geometry for Coating Without Plugging
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Solution Overview
Problem
Implementing ceramic matrix composites (CMCs) in gas turbine engine airfoils faces challenges due to the complexity and cost associated with applying protective coatings over cooling holes without disturbing the film cooling effect, which can lead to coating integrity issues and manufacturing inefficiencies.
Innovation Solution
The use of counterbored cooling holes in CMC components allows for the application of coatings without plugging, maintaining the film cooling effect by designing the cooling holes with a metering and diffuser portion geometry that ensures the coating only covers a portion of the diffuser section, thereby eliminating the need for plugging and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cooling holes are used with plugging for coating application, then coating integrity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The cooling hole is divided into two distinct sections: a metering portion and a diffuser portion. This segmentation allows the coating to be applied only to the diffuser portion while the metering portion remains unplugged, thereby maintaining coating integrity without requiring complete plugging of the cooling hole, thus reducing manufacturing complexity
Solution Approach 2:
Different portions of the cooling hole are given different properties: the metering portion maintains its open structure for proper cooling function, while the diffuser portion is coated for protection. This local differentiation allows coating application without compromising the cooling effect or requiring full plugging
2Reliability
If cooling holes are plugged for coating application, then coating integrity is improved, but film cooling effect is disturbed
Solution Approach 1:
By segmenting the cooling hole into metering and diffuser portions, the invention allows coating to be applied only where necessary (diffuser portion) while leaving the metering portion open to maintain proper cooling flow characteristics, thus preserving the film cooling effect
Solution Approach 2:
Instead of completely plugging the cooling hole for coating application, only the diffuser portion is coated while the metering portion remains functional. This partial action approach maintains coating integrity without excessively interfering with the cooling function
3Reliability
If conventional coating methods are used over cooling holes, then coating coverage is improved, but manufacturing time and cost increase
Solution Approach 1:
The cooling holes are pre-designed with the counterbored geometry (metering and diffuser portions) before coating application. This preliminary structural preparation allows for straightforward coating application to only the diffuser portion, eliminating the need for complex plugging and removal processes, thus improving manufacturing efficiency
Solution Approach 2:
The coating is applied only to the diffuser portion rather than the entire cooling hole, which is sufficient for protection while reducing coating material usage and application time, thereby improving manufacturing efficiency without compromising necessary coverage
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A ceramic matrix composite component (100) includes a ceramic matrix composite wall; a coating (107) disposed on the wall; and a cooling hole (102) formed in the wall. The cooling hole (102) has a metering section (104) defined along a first axis (C1) and a diffuser section (106) defined along a second axis (C2) that is offset from the first axis (C1). The cooling hole (102) has a total length (L) defined along the first axis (C1), the total length (L) being the sum of a length of the metering portion (104) and a length of the diffuser portion (102). The length of the metering portion (104) is between about 40 percent and about 85 percent of the total length (L). A ceramic matrix composite airfoil (100) and a method of applying a coating (107) to a ceramic matrix composite component (100) are also disclosed.