Multi-Lobed Cooling Holes for Gas Turbine Engine Walls
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Solution Overview
Problem
Conventional cooling techniques for gas turbine engine components face challenges such as flow separation and increased cooling flow requirements due to high gas path temperatures, leading to reduced efficiency and increased wear, particularly in the hot sections of the compressor, combustor, and turbine.
Innovation Solution
The implementation of multi-lobed cooling holes with specific inlet, metering, diffusing, and outlet geometries that reduce flow separation and enhance film cooling coverage, allowing for improved film effectiveness and reduced cooling fluid requirements, thereby maintaining engine efficiency and extending service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cooling techniques are used in gas turbine engine components, then cooling function is provided, but flow separation occurs and cooling flow requirements increase
Solution Approach 1:
The cooling hole is divided into multiple functional sections: inlet section, metering section, diffusing section, and outlet section. The diffusing section is further segmented into multiple lobes that distribute cooling flow more effectively across the surface, reducing flow separation and improving cooling effectiveness while reducing overall cooling flow requirements.
Solution Approach 2:
The cooling hole geometry transitions from a simple circular cross-section to a multi-lobed diffusing section that expands in the lateral dimension. This dimensional change allows the cooling flow to spread more effectively across the component surface, enhancing film cooling coverage and reducing the quantity of cooling fluid needed.
2Reliability
If conventional cooling holes are used, then cooling is provided, but film cooling coverage is insufficient and flow separation increases
Solution Approach 1:
The diffusing section is segmented into multiple lobes that create multiple discrete cooling jets across the surface. This segmentation prevents large-scale flow separation by distributing the cooling flow into smaller, more manageable streams that attach better to the surface.
Solution Approach 2:
The metering section and diffusing section utilize curved geometries with specific radius ratios to promote smooth flow transition and reduce flow separation. The curved surfaces guide the cooling flow more effectively along the component surface, enhancing film cooling coverage.
3Power
If high gas path temperatures are operated to improve efficiency, then power output increases, but component wear increases and cooling requirements increase
Solution Approach 1:
The cooling hole geometry parameters are optimized to operate effectively at high blowing ratios that correspond to high gas path temperatures. The diffusing section angle, lobe configuration, and metering section dimensions are specifically designed to maintain effective cooling under high-temperature operating conditions, allowing the engine to operate at higher power levels while protecting components from thermal damage.
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
The multi-lobed cooling holes provide enhanced film cooling coverage, reduce the likelihood of flow separation, and operate effectively at high blowing ratios, thus maintaining engine efficiency and extending the service life of gas turbine engine components.
Implementation Method 1
enhance film cooling coverage, allowing for improved film effectiveness
Implementation Method 2
reduce flow separation
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A component for a gas turbine engine includes a wall and a cooling hole extending through the wall. The wall has a first surface and a second surface. The cooling hole includes a metering section extending downstream from an inlet in the first surface of the wall and a diffusion section extending from the metering section to an outlet in the second surface of the wall. The diffusion section includes a first plurality of lobes diverging longitudinally and laterally from the metering section on a first side of a centerline axis of the cooling hole and a second plurality of lobes diverging longitudinally and laterally from the metering section on a second side of the centerline axis.