Airfoil Cooling Passages Using Ceramic Cores
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Solution Overview
Problem
Current airfoil tooling designs with straight cooling holes are limited by manufacturing constraints, restricting the geometry and efficiency of convective cooling, as they cannot accommodate complex angles or desired lengths and shapes, which affects the cooling performance of turbine blades in gas turbine engines.
Innovation Solution
The use of ceramic and refractory metal cores in a mold to cast an airfoil structure with S-shaped cooling passages that interconnect interior and exterior surfaces, allowing for varied geometry and inclusion of trip strips for enhanced heat transfer and pressure control, replacing traditional straight holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If straight cooling holes are used in traditional airfoil tooling designs, then manufacturing is simpler, but cooling efficiency and geometry optimization are limited
Solution Approach 1:
The patent applies curved S-shaped cooling passages instead of straight cooling holes. The S-shaped geometry allows the cooling fluid to follow a curved path through the airfoil, increasing the surface area for heat transfer and improving cooling efficiency while maintaining manufacturability through ceramic core molding techniques.
Solution Approach 2:
The patent transitions from one-dimensional straight holes to three-dimensional S-shaped passages with complex spatial geometry. This dimensional complexity enables better heat transfer by increasing the cooling surface area and optimizing fluid flow paths through the airfoil structure.
2Reliability
If complex S-shaped cooling passages are implemented, then cooling efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The patent uses ceramic cores as intermediary tools to create the complex S-shaped cooling passages. These removable ceramic cores are inserted into the mold cavity in the desired S-shaped configuration, allowing the molten metal to flow around them and form the negative space of the cooling passages. After casting, the ceramic cores are removed, leaving the desired complex geometry without requiring complex mold cavities.
Solution Approach 2:
The ceramic cores are prepared and positioned in advance within the mold before casting. This preliminary action allows the complex S-shaped geometry to be pre-formed using simple mold cavities, reducing the actual manufacturing complexity during the casting process itself.
3Ease of manufacture
If cooling hole angles are restricted to minimal angles with airfoil exterior surface, then drilling is easier, but cooling passage optimization is limited
Solution Approach 1:
The S-shaped cooling passages enable complex angle variations throughout the passage length, allowing optimal entry and exit angles at the airfoil surface while maintaining complex intermediate angles for enhanced cooling. The curved geometry provides flexibility in angle optimization that straight drilling cannot achieve.
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 approach enables more efficient convective cooling by allowing for complex geometries and optimized pressure drops, improving the cooling performance and heat transfer characteristics of turbine blades, thereby enhancing the operational efficiency of gas turbine engines.
Implementation Method 1
Cooling circuits are formed within the airfoil to circulate cooling fluid, such as compressor bleed air. Air flows through the channels and cools the airfoil
Implementation Method 2
Some advanced cooling designs use one or more radial cooling passages arranged between the cooling channels and an airfoil exterior surface that extend from the root toward the tip. The cooling passages provide high convective cooling.
Data Source
Figure 1
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AI summary
An example method of manufacturing an airfoil (30) includes providing a ceramic core (64) corresponding to an interior cooling channel (42). A refractory metal core (66) is provided that corresponds to a cooling passage (46). The cores are arranged in a mold (60). An airfoil structure (30) is cast about the cores to provide a turbine engine airfoil. The turbine engine airfoil (30) includes a wall (44) providing the interior cooling channel (42) and an exterior airfoil surface (34). The cooling passage (46) is provided in the wall (44) and fluidly connects the interior cooling channel (42) to the exterior airfoil surface (34). The cooling passage (46) includes multiple inlets (48) and multiple outlets (50) respectively adjoining the interior cooling channel (42) and the exterior airfoil surface (34). At least one of a first inlet (48) and outlet (50) has a different structural flow characteristic than at least one of a second inlet and outlet (48,50).