Gas Turbine Rotor Blade Cooling Aperture Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current cooling methods for gas turbine engine rotor blades, particularly high pressure turbine blades, require significant amounts of coolant air, which reduces engine efficiency and is not effectively distributed for optimal heat transfer, especially at the leading and trailing edges where cooling is most challenging.
Innovation Solution
The design incorporates aerofoils with non-linear centerlines for coolant apertures, featuring elliptical entries and circular or elliptical exits, angled to direct coolant flows perpendicularly onto the chamber walls, enhancing the pressure ratio and heat transfer efficiency while minimizing coolant usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling methods (internal convection and external films) are used for rotor blades, then cooling coverage is provided, but coolant air consumption is excessive and engine efficiency deteriorates
Solution Approach 1:
The cooling system is segmented into multiple functional zones: impingement cooling zones with arrays of holes for intense localized cooling, and serpentine passage zones for distributed cooling. This segmentation allows different cooling methods to be applied to different blade regions, optimizing coolant usage while maintaining effective temperature control.
Solution Approach 2:
The patent applies impingement cooling with high-velocity jets at specific locations (leading edges, trailing edges, and suction surfaces) where heat flux is highest, while using serpentine passages in other regions. This local quality approach concentrates cooling resources where most needed, reducing overall coolant consumption while maintaining blade integrity.
2Temperature
If separate chambers or cavities with impingement air are configured for leading and trailing edges, then cooling is provided to difficult-to-cool areas, but device complexity increases
Solution Approach 1:
The patent merges the impingement cooling function and serpentine passage cooling into a single integrated cooling structure within the blade. The impingement holes and serpentine passages share common coolant supply channels and are structurally integrated, eliminating the need for separate chambers and reducing overall device complexity while maintaining effective cooling of leading and trailing edges.
3Reliability
If higher pressure ratios across impingement holes are used to improve cooling effectiveness, then heat transfer improves, but feed pressure requirements increase and coolant leakage increases
Solution Approach 1:
The patent employs arrays of small-diameter impingement holes that create high-velocity dynamic jets from moderate pressure differentials. The dynamic nature of these jets provides intense cooling without requiring excessively high feed pressures, thereby reducing coolant leakage while maintaining high cooling effectiveness through the kinetic energy of the impingement flows.
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 increases the impingement pressure ratio without increasing feed pressure, achieving focused heat transfer and improved cooling effectiveness, leading to reduced aerofoil leading edge temperatures and increased durability, thus allowing higher gas temperatures and improved engine efficiency.
Implementation Method 1
a plurality of feed apertures is defined in the divider wall to supply the coolant to impinge on the chamber wall
Implementation Method 2
achieving focused heat transfer and improved cooling effectiveness
Implementation Method 3
internal convection and external films have been utilised as the primary methods for cooling rotor blades
Implementation Method 4
the coolant air temperature will be in the order of 700 to 1,000 K whilst the gas temperature in the high pressure turbine stage will be in excess of 2,100 K
Data Source
AI summary
Cooling within aerofoils (30, 47, 67, 87) is a requirement in order that the materials from which the aerofoil (30, 47, 67, 87) is created can remain within acceptable operational parameters. Traditionally static pressure as well as enhanced dynamic pressure impingement flows have been utilized but there are problems with regard to achieving a necessary over pressure to avoid hot gas ingestion or reduced cooling effect. It will be appreciated that fluid flows and in particular coolant fluid flows must be used most appropriately in order to maintain operational efficiency. By providing a plurality of feed apertures (41, 61, 81) which are shaped to have an entry portion (51, 71, 91) which is generally elliptical and an exit portion (52, 72, 92) it is possible to grab and turn a proportion of a feed flow (44, 64, 84) for substantially perpendicular or other angular presentation to an opposed surface of a cooling chamber (42, 62, 82) within which cooling is required.