Turbine Cooling Passage Cap Geometry for Leading-Edge Film Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in turbine component cooling lies in the difficulty of creating complex film cooling passage geometries, especially at the leading edge, where traditional manufacturing methods fail to achieve effective coolant coverage and efficiency due to the small radius of curvature, and the need to reduce coolant usage while maintaining part temperature, which is exacerbated by the susceptibility of thermal barrier coatings to spalls.
Innovation Solution
The method involves forming a cooling passage with a metering section and a diffuser area, where a metal cap element is used to close the diffuser area, creating a diffusion section that extends to the external surface, allowing for customized coolant flow and increased coverage, and enabling the use of single crystal alloys or other materials not feasible with conventional drilling or additive manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional drilling methods are used to create cooling passages at the leading edge, then manufacturing is simpler, but cooling effectiveness is reduced due to radial orientation and sharp turns
Solution Approach 1:
The cooling passage is divided into multiple sections: a metering section with radial orientation for simple manufacturing, and a diffusion section with complex geometry for high cooling effectiveness. This segmentation allows each section to be optimized independently - the metering section can be drilled traditionally while the diffusion section provides the required flow control and surface coverage.
Solution Approach 2:
A cap element is introduced as an intermediary component that forms the diffusion section of the cooling passage. This cap element contains the complex internal geometry that would be difficult to manufacture directly in the airfoil, while the metering section can be manufactured using conventional drilling methods.
2Loss of energy
If the number of cooling passages is reduced to decrease coolant usage, then turbine efficiency increases, but cooling coverage must be increased per passage
Solution Approach 1:
The diffusion section changes the flow parameters of the coolant by diffusing it laterally across the surface. This diffusion process increases the lateral coverage of each cooling passage, allowing fewer passages to achieve the same overall cooling effect, thereby reducing total coolant consumption while maintaining cooling effectiveness.
3Manufacturing precision
If shaped diffusion exit holes are used to improve cooling effectiveness, then cooling performance increases, but manufacturing becomes difficult due to small leading edge radius
Solution Approach 1:
The cooling passage is divided into a metering section that can be manufactured with conventional radial drilling, and a diffusion section that provides the complex shaped geometry for improved cooling. This segmentation allows the difficult diffusion geometry to be manufactured separately and assembled, rather than requiring complex drilling at the leading edge.
Solution Approach 2:
The cap element acts as an intermediary that contains the complex diffusion geometry. Instead of drilling complex shapes directly into the airfoil at the difficult leading edge location, the cap element is manufactured separately with the required geometry and then installed, simplifying the overall manufacturing process.
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 enhances averaged film cooling effectiveness and coolant coverage, increasing turbine efficiency and part durability by allowing more complex shaped cooling passages, even at the leading edge, and enabling adaptive cooling during operation.
Implementation Method 1
the coolant creates a cooling film, i.e., a flow across and close to the surface of the airfoil, which extends downstream along a surface of the airfoil
Implementation Method 2
Airfoils are typically covered with a high concentration of a thermal barrier coating (TBC)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Methods of forming a cooling passage on a turbine component 200 having a component wall with an internal surface 212 and an external surface 214, are disclosed. An opening 220 is formed passing through the component wall and fluidly connecting the internal and external surfaces. The opening includes a metering section 222 extending from the internal surface to a metering end, and a diffuser area 226 extending from the metering end to the external surface. A preformed cap element is added to close a portion of the diffuser area to form the cooling passage with a diffusion section 242 extending from the metering end to the external surface. The preformed metal cap element includes a projection 244 extending internally of the external surface and into the diffusion area to define an internally facing section of the diffusion section. The cooling passage extends through the component wall and fluidly connects the internal surface and the external surface.