Gas Turbine Cooling Hole with Embedded Lobes
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Solution Overview
Problem
Gas turbine engine components exposed to high temperatures require effective cooling methods to prevent damage from hot combustion gases, but existing cooling holes often lead to vortex formation, reducing the effectiveness of film cooling.
Innovation Solution
The design incorporates cooling holes with embedded lobes and a curved transition portion, which diverge and converge to minimize vortex formation, allowing cooling air to remain on the outer skin for a longer period and provide more effective film cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cooling holes are used, then the structure is simple and easy to manufacture, but vortex formation occurs that reduces film cooling effectiveness
Solution Approach 1:
The cooling hole is divided into multiple functional sections: a metering section with constant cross-sectional area and a diffusion section with varying cross-sectional area. This segmentation allows each section to perform its specific function - the metering section controls flow rate while the diffusion section reduces velocity and extends cooling air residence time, thereby improving film cooling effectiveness without excessive complexity
Solution Approach 2:
The diffusion section incorporates a curved transition portion with a specific curvature radius that is at least 10% of the diffusion section length. This curved geometry smoothly transitions the flow from the metering section, reducing flow separation and vortex formation while maintaining effective film cooling along the outer skin surface
2Duration of action of stationary object
If cooling air is discharged to provide film cooling, then the component is protected from hot gases, but the cooling air remains on the outer skin for a short duration reducing cooling efficiency
Solution Approach 1:
The diffusion section is designed with a varying cross-sectional area that dynamically adapts to the flow conditions. The area increases along the diffusion section length, which dynamically reduces the cooling air velocity while maintaining mass flow rate. This dynamic area change allows the cooling air to remain on the outer skin for an extended period, improving residence time and cooling effectiveness
3Reliability
If the diffusion section extends into the coating layer, then the cooling hole integration is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The design specifies parameter ranges rather than fixed values to accommodate manufacturing variations. The curvature radius is defined as at least 10% of the diffusion section length, and the diffusion angle is specified within a range of 10° to 60°. These parameter specifications provide manufacturing flexibility while ensuring reliable integration with the coating layer and effective cooling performance
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 design enhances the duration of cooling air on the outer skin, improving the film cooling efficiency and protecting components from extreme temperatures.
Implementation Method 1
existing cooling holes often lead to vortex formation, reducing the effectiveness of film cooling
Implementation Method 2
The film cooling air provides a barrier that protects the underlying substrate of the component from the hot combustion gases
Implementation Method 3
The film cooling air provides a barrier that protects the underlying substrate of the component from the hot combustion gases that are communicated along the core flow path
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A component for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a wall having an internal surface, an outer skin and a cooling hole having an inlet extending from the internal surface and merging into a metering section, and a diffusion section downstream of the metering section that extends to an outlet located at the outer skin. At least two lobes are embedded within the diffusion section of the cooling hole. At least one surface of each of the at least two lobes is at least partially cylindrical.