Airfoil Cooling Holes Lobed Diffuser Film Cooling
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Solution Overview
Problem
Gas turbine engines face challenges in efficiently cooling their hot sections due to high gas path temperatures and pressures, leading to thermal mechanical fatigue and oxidation erosion wear, which conventional cooling designs struggle to mitigate effectively.
Innovation Solution
The design incorporates cooling holes with specific geometries, featuring a metering section and a diffusing section with lobed portions and ridge surfaces, which enhance film cooling performance by increasing the meter-to-diffuser area ratio and reducing flow separation, thereby improving the lateral spreading and effectiveness of the cooling film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cooling designs are used, then cooling coverage is achieved, but cooling effectiveness is insufficient due to flow separation and limited lateral spreading
Solution Approach 1:
The cooling hole is divided into distinct functional sections: a metering section with constant cross-sectional area and a diffusing section with expanding area. This segmentation allows independent optimization of flow control and lateral spreading, improving cooling effectiveness while reducing flow separation.
Solution Approach 2:
Different sections of the cooling hole have different geometric properties tailored to specific functions: the metering section maintains uniform flow, while the diffusing section promotes lateral spreading. The outlet geometry is specifically designed to match the airfoil surface, enhancing local cooling quality where it is most needed.
2Reliability
If cooling air flow is increased, then cooling effectiveness improves, but engine efficiency decreases due to higher cooling air requirements
Solution Approach 1:
The cooling hole geometry parameters are optimized to achieve better cooling performance with reduced flow. The meter-to-diffuser area ratio and diffusing section angle are specifically designed to maximize lateral spreading and minimize flow separation, allowing effective cooling with lower cooling air requirements, thus preserving engine efficiency.
3Reliability
If cooling hole geometry is optimized for lateral spreading, then film cooling performance improves, but manufacturing complexity increases
Solution Approach 1:
The complex cooling hole geometry is segmented into two manageable sections: a simple cylindrical metering section and an expanding diffusing section. This segmentation simplifies the manufacturing process while maintaining the optimized geometry needed for superior film cooling performance and lateral spreading.
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 reduces the cooling air flow requirements, increases the durability of hot section components, and maintains or enhances engine efficiency by creating a robust and effective film cooling layer that protects the components from high temperatures.
Implementation Method 1
enhance film cooling performance by increasing the meter-to-diffuser area ratio and reducing flow separation, thereby improving the lateral spreading and effectiveness of the cooling film
Implementation Method 2
cooling hole defines a fluid path through the component wall from the inlet to the outlet
Data Source
AI summary
Component for gas turbine engines are described. The components include a component wall having an inner wall surface and an outer wall surface and a cooling hole formed within the component wall. The cooling hole has an inlet formed in the inner wall surface and an outlet formed in the outer wall surface and defines a fluid path through the component wall. The cooling hole has a metering section extending from the inlet to a transition point and a diffusing section extending from the transition point to the outlet. The metering section is defined by a uniform geometry and the diffusing section is defined by a lobed portion that extends from the transition point toward the outlet. The lobed portion has a first lobe and a second lobe divided by a ridge surface and each lobe defines continuous curved surfaces along the length of the ridge surface.