Multi-Lobe Cooling Holes for Gas Turbine Film Cooling
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Solution Overview
Problem
Conventional gas turbine engines face challenges in effectively regulating the operating temperature of turbine components due to high temperatures, leading to potential mechanical issues and reduced component lifespan, as existing film cooling methods often require high cooling air flow rates.
Innovation Solution
The implementation of gas turbine engine components with a plurality of cooling holes featuring a cylindrical upstream portion transitioning into a multi-lobed downstream portion, which enhances film cooling by maintaining cooling air attachment to the surface and minimizing mixing with mainstream gas flow, thereby providing a more uniform and efficient cooling effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cylindrical cooling holes are used, then the structure is simple and easy to manufacture, but high cooling air flow rates are required to achieve satisfactory temperature control
Solution Approach 1:
The cooling hole is divided into multiple functional sections: an upstream cylindrical portion and a downstream multi-lobed portion with 2-5 lobes. This segmentation allows the cooling air flow to be distributed across multiple lobes, improving cooling effectiveness and reducing the total cooling air flow rate required while maintaining manufacturing feasibility
Solution Approach 2:
The cooling hole transitions from a simple cylindrical shape to a multi-lobed cross-sectional shape in the downstream portion. This dimensional change creates multiple cooling jets that spread cooling air more effectively across the surface, reducing the overall cooling air demand while improving temperature control
2Temperature
If high cooling air flow rates are used, then satisfactory temperature control is achieved, but radial velocity of cooling air increases causing surface separation and reduced cooling efficiency
Solution Approach 1:
By dividing the cooling hole into upstream and downstream portions with different geometries, the multi-lobed downstream section creates multiple lower-velocity jets that reduce radial velocity and prevent surface separation while maintaining effective temperature control
Solution Approach 2:
The geometry parameters of the cooling hole are changed from a uniform cylinder to a multi-lobed configuration with specific lobe counts (2-5 lobes) and defined transition lengths. This parameter change optimizes the velocity distribution of cooling air, reducing radial velocity and preventing flow separation
3Ease of manufacture
If uniform cooling holes are formed along a line parallel to the leading edge, then the cooling air distribution is straightforward, but the adiabatic effectiveness and uniformity of cooling are insufficient
Solution Approach 1:
The cooling hole is segmented into upstream and downstream portions with the downstream multi-lobed section creating multiple cooling streams that improve cooling uniformity and adiabatic effectiveness across the component surface
Solution Approach 2:
The transition to a multi-lobed cross-sectional shape adds complexity to the hole geometry, improving cooling uniformity and adiabatic effectiveness by distributing cooling air across multiple lobes that contact different areas of the component surface
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 configuration reduces radial velocity of cooling air, prevents surface separation, and promotes a smoother transition, resulting in improved film cooling and extended component lifespan by optimizing the distribution and adiabatic effectiveness of cooling air.
Implementation Method 1
maintaining cooling air attachment to the surface and minimizing mixing with mainstream gas flow
Implementation Method 2
Film cooling attempts to maintain the airfoils at temperatures that are suitable for their material and stress level
Data Source
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AI summary
An engine component includes a body; and a plurality of cooling holes formed in the body, at least one of the cooling holes having a multi-lobed shape with at least a first lobe, a second lobe, and a third lobe.