Multiwall Airfoil Core Boss Positioning
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Solution Overview
Problem
Traditional methods for controlling location and rib wall thickness in multiwall casting processes, such as using bumpers, lead to uncertainties in cooling flow distribution and often result in holes between cavities, making it difficult to achieve precise cooling flow and rib wall thickness control in turbine systems.
Innovation Solution
The use of bosses extending from a cantilevered core section to the outer profile of a multiwall airfoil core, which provides positional and thickness control during the casting process, eliminating the need for bumpers and ensuring precise positioning and thickness control without forming holes between center plenums and outer cooling passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bumpers are used to control location and rib wall thickness, then positioning control is provided, but holes form between cavities leading to uncertain cooling flow distribution
Solution Approach 1:
The patent removes the bumper component entirely from the core design. Instead of using separate bumpers to control gap distances, the core itself is designed with integrated thickness control features where the core material directly defines the desired gap dimensions between cooling passages and the airfoil wall, eliminating the source of hole formation.
Solution Approach 2:
Rather than using protruding bumpers that can contact and potentially bridge gaps between cavities, the invention inverts the approach by using recessed or integrated thickness control features within the core structure. The core's own geometry, rather than added components, defines the precise spacing and prevents hole formation at critical interfaces.
2Manufacturing precision
If bumpers are used for positioning control, then location control is achieved, but the number of holes formed is unknown creating uncertainty
Solution Approach 1:
The core design is self-sufficient with integrated thickness control features built directly into its structure. The core automatically maintains precise positioning and gap control through its own geometry without requiring external bumpers, ensuring consistent cooling flow paths and eliminating variability in hole formation.
3Ease of manufacture
If traditional casting methods are used, then the process is simple, but expensive MRI measurements are needed to verify rib wall thickness
Solution Approach 1:
The desired rib wall thickness and gap dimensions are pre-built into the core's geometry during core fabrication. By incorporating thickness control features directly into the core design before casting, the final airfoil part achieves the target dimensions without requiring post-casting verification through expensive MRI scanning.
Data Source
Figure 1
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Figure 3
AI summary
A core 10 for an airfoil casting, including: a cantilevered core section 234; and a boss extending 252 from the cantilevered core section to an outer profile of the core.