Tailored Cooling Holes with Metering and Diffuser Portions
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Solution Overview
Problem
Gas turbine engine components within the mainstream hot gas flow path face challenges in efficient cooling due to high temperatures, leading to potential overheating and mechanical issues, necessitating improved film cooling mechanisms.
Innovation Solution
The implementation of gas turbine engine components with a plurality of cooling holes featuring a metering portion of constant cross-sectional area and a diffuser portion extending from the metering portion to the external surface, designed to enhance the effectiveness of the cooling film on the surface by directing cooling air laterally and diffusing it for improved heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cooling holes are used in turbine components, then the component structure is simple and easy to manufacture, but the film cooling effectiveness is insufficient leading to overheating and reduced component life
Solution Approach 1:
The cooling hole is divided into distinct functional segments: a metering portion with constant cross-sectional area for flow control, and a diffuser portion with expanding cross-section for flow diffusion. This segmentation allows each portion to optimize its specific function, improving overall cooling effectiveness while maintaining manufacturability
Solution Approach 2:
Different portions of the cooling hole are given different geometric properties tailored to their specific functions. The metering portion has a constant cross-section with offset maximum height for stable flow metering, while the diffuser portion has an expanding cross-section for flow diffusion. This local differentiation optimizes cooling performance without requiring complete redesign of the entire hole structure
2Reliability
If cooling air is ducted through internal passages and vented through holes, then the component can be cooled, but the cooling distribution is non-uniform and film cooling effectiveness is limited
Solution Approach 1:
The cross-sectional area parameter of the cooling hole is varied along its length to achieve desired flow characteristics. The metering portion maintains constant cross-sectional area for stable flow, while the diffuser portion expands the cross-section to diffuse the cooling air laterally, creating more uniform cooling distribution and improved film coverage on the component surface
3Ease of manufacture
If simple cylindrical cooling holes are used, then the manufacturing process is simple, but the cooling air is not effectively directed laterally for film cooling
Solution Approach 1:
The cooling hole geometry is made asymmetric with respect to the component surface, featuring an offset maximum height in the metering portion. This asymmetry directs the cooling air flow laterally upon exit, improving film cooling effectiveness by positioning the cooling jet closer to the surface and enhancing lateral spread, while still being manufacturable using standard drilling and machining processes
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 enhances film cooling effectiveness, leading to a more uniform cooling distribution and reduced temperature on the surface, potentially doubling the service life of the components by improving film cooling by over 20% compared to traditional designs.
Implementation Method 1
a metering portion with a constant cross-sectional area
Implementation Method 2
a diffuser portion extending from the metering portion to the external surface of the body
Implementation Method 3
vent the cooling air through holes formed in the airfoil... provide a film of cooling air over portions of the airfoil
Data Source
AI summary
An engine component includes a body having an internal surface and an external surface, the internal surface at least partially defining an internal cooling circuit. The component further includes a plurality of cooling holes formed in the body and extending between the internal cooling circuit and the external surface of the body. The plurality of cooling holes includes a first cooling hole with a metering portion and a diffuser portion extending from the metering portion to the external surface of the body.