Elliptical Ceramic Core for Gas Turbine Cooling Holes
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Solution Overview
Problem
Existing ceramic cores used in investment casting for gas turbine engines are fragile and prone to breakage during fabrication and metal casting, especially when creating intricate cooling passages, limiting their stability and effectiveness.
Innovation Solution
The use of a core element with an investment core body made of ceramic material, featuring an extension with an elliptical cross-section and a connection portion, which provides greater stability and durability by preventing breakage during the casting process, allowing for the creation of more robust cooling holes that enhance air flow tuning and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing ceramic cores with long thin rods are used to simulate machined cylindrical holes, then cooling passages can be formed in turbine components, but the cores are fragile and prone to warpage and breaking during fabrication and metal casting
Solution Approach 1:
The patent replaces long thin cylindrical rods with spherical or ball-shaped core elements. This geometric transformation eliminates the structural weakness of thin rods while maintaining the ability to form cooling passages. The spherical shape provides inherent structural stability and resistance to warpage and breaking during fabrication and casting processes.
Solution Approach 2:
The patent employs ceramic materials with specific compositional characteristics to enhance core strength while maintaining stability. The ceramic composition is selected and formulated to provide both the necessary strength to prevent breakage and the stability to maintain geometric integrity throughout the manufacturing process.
2Ease of manufacture
If fragile ceramic cores are used, then investment casting can proceed, but the cores break during fabrication and metal casting limiting their effectiveness
Solution Approach 1:
The spherical geometry of the core elements provides structural robustness that enables them to withstand the mechanical stresses of fabrication and casting operations. This shape maintains integrity throughout the manufacturing process, ensuring reliable production of turbine components with cooling passages.
3Reliability
If stable cooling holes are created, then air cooling performance is enhanced, but the core structure becomes more complex
Solution Approach 1:
The spherical core elements provide stable, break-resistant structures that maintain their geometry throughout manufacturing, ensuring consistent cooling hole formation. This geometric simplicity actually reduces overall system complexity compared to fragile rod-based systems that require careful handling and assembly procedures.
Data Source
AI summary
A core element of an investment core for use in a casting process used to produce an airfoil includes an investment core body, an extension connected to and protruding from the investment core body, and a connection portion connected to the investment core body and to the extension. The investment core body includes a ceramic material. A shape of the extension includes a tube with a centerline axis passing through a center of the extension. A shape of a cross-section of the extension taken along a plane perpendicular to the extension centerline axis includes an ellipse. The extension is connected to the investment core body by the connection portion.