Jacketed Core for Gas Turbine Internal Passages
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Solution Overview
Problem
Existing methods for forming components with internal passages are hindered by fragile ceramic cores, high production costs, and the inability to efficiently create complex passage curvatures, particularly in high-temperature applications like gas turbines, due to the fragility of ceramic cores and time-consuming drilling processes.
Innovation Solution
A jacketed core is used, comprising a hollow structure from a first material that is partially absorbable by the molten component material, with an inner core positioned within the mold to define the passage, providing structural reinforcement and allowing for the formation of complex passage shapes without the fragility issues of unjacketed cores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional ceramic cores are used to form internal passages, then the internal passages can be formed in the component, but the cores are fragile and difficult/expensive to produce and handle without damage
Solution Approach 1:
The patent applies nesting by placing a sturdy outer shell around a fragile inner core. The outer shell is formed from material that provides structural support, while the inner core defines the internal passage geometry. This nested structure allows the fragile core to be handled and processed without damage while still achieving the desired internal passage formation.
Solution Approach 2:
The patent uses composite materials by combining an outer shell material with an inner core material. The outer shell is made from a material that is absorbable by molten metal (such as a sugar-based or starch-based material), while the inner core is made from a different material that provides the structural definition for the internal passage. This composite approach allows each material to contribute its specific properties to the overall system.
2Manufacturing precision
If ceramic cores are used in investment casting, then internal passages can be formed, but the cores lack sufficient strength to withstand injection of wax material
Solution Approach 1:
The outer shell is injected with wax material during the investment casting process, and the inner core is nested within this shell. The shell provides the necessary strength to withstand the injection pressure, while the inner core remains protected and intact to define the internal passage geometry. This resolves the contradiction by separating the load-bearing function (shell) from the geometry-defining function (core).
Solution Approach 2:
The outer shell acts as an intermediary between the wax injection process and the inner core. It absorbs the mechanical stress of the injection process, protecting the inner core from damage while still allowing the core to fulfill its geometry-defining role. The shell mediates the interaction between the injection process and the core material.
3Manufacturing precision
If drilling processes are used to form internal passages, then passages can be created in components, but the process is time-consuming and expensive
Solution Approach 1:
The internal passage geometry is pre-defined by the inner core before the component is formed. The core is placed in the mold cavity, and the component material is formed around it, creating the internal passage in a single casting operation. This eliminates the need for subsequent drilling or machining operations, significantly reducing production time and cost while maintaining manufacturing precision.
Solution Approach 2:
The patent merges the internal passage formation process with the component forming process. Instead of forming the component and then creating the passage separately (drilling), both operations are combined into a single casting process. The inner core serves as a permanent mold for the internal passage, allowing simultaneous formation of both the component exterior and the internal passage.
4Manufacturing precision
If drilling processes are used to form internal passages, then passages can be created, but complex passage curvatures cannot be produced
Solution Approach 1:
The inner core can be manufactured with complex curved geometries that define the desired internal passage shape. Unlike drilling, which is limited to relatively simple geometries, the core can be formed with any curvature or complex shape using molding or additive manufacturing techniques. This allows the internal passage to match the exact desired geometry, including complex curvatures, directly from the core design.
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 method reduces production costs and fragility risks, enables the creation of longer, heavier, and more complex internal passages, and allows for the integration of passage wall features, enhancing the structural integrity and performance of components like rotor blades and stator vanes in gas turbines.
Implementation Method 1
the component material in the molten state at least partially absorbs the first material from a portion of the jacketed core within the cavity
Data Source
AI summary
A method of forming a component having an internal passage defined therein includes positioning a jacketed core with respect to a mold. The jacketed core includes a hollow structure formed from a first material, and an inner core formed from an inner core material disposed within the hollow structure. The method also includes introducing a component material in a molten state into a cavity of the mold, such that the component material in the molten state at least partially absorbs the first material from a portion of the jacketed core within the cavity. The method further includes cooling the component material in the cavity to form the component, and removing the inner core material from the component to form the internal passage.