Cooled Turbine Airfoil Geometry for Precise Thin-Wall Cooling
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Solution Overview
Problem
In gas turbine engines, existing airfoil designs face challenges in achieving both efficient aerodynamics and internal cooling with small wall thicknesses, as manufacturing precision is compromised by differential thermal expansion during the casting process, leading to large tolerances in cooling channels.
Innovation Solution
A cooled airfoil design with a specific geometry and manufacturing method where the mold and core are aligned to minimize thermal expansion effects, allowing for thin wall thicknesses and precise cooling channel placement, with straight and bent sections that follow the leading and trailing edge shapes, enabling efficient coolant use and improved structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the wall thickness is reduced to improve cooling efficiency, then coolant use efficiency is improved, but manufacturing precision deteriorates due to differential thermal expansion
Solution Approach 1:
The patent changes the geometric parameters of the core, specifically designing straight and bent sections with specific radius ratios (R1/R2 between 0.5-2.0) to compensate for differential thermal expansion. This allows the core to maintain dimensional stability during casting while enabling thin wall thicknesses for efficient cooling
Solution Approach 2:
The patent explicitly addresses thermal expansion by designing the core geometry to accommodate differential thermal expansion between the mold and core materials. The curved sections with specific radius ratios allow the core to expand differently than the mold without compromising the precision of the cooling channels
2Productivity
If the airfoil geometry is adapted to axially divergent flow to improve aerodynamics, then aerodynamic efficiency is improved, but manufacturing complexity increases due to 3D curved and twisted geometry
Solution Approach 1:
The patent segments the airfoil geometry into distinct sections: a hub-side section with straight leading and trailing edges, and a tip-side section with curved geometry. This segmentation allows the complex 3D aerodynamic shape to be achieved while maintaining manufacturing simplicity in the hub region where cooling channels are most critical
Solution Approach 2:
The patent applies different geometric characteristics to different parts of the airfoil: the hub-side section has straight edges for manufacturing simplicity and structural integrity, while the tip-side section has curved geometry for optimal aerodynamics. This local differentiation resolves the contradiction between aerodynamic efficiency and manufacturing complexity
3Loss of energy
If the wall thickness is reduced to follow cooling channel geometry, then cooling efficiency is improved, but structural integrity deteriorates
Solution Approach 1:
The patent optimizes the wall thickness parameter to a specific range (2.5-2.9mm at leading edge, 1.3-1.5mm at trailing edge) that balances cooling efficiency with structural integrity. The straight hub-side geometry further reinforces structural strength while maintaining thin walls for effective cooling
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 solution enables improved aerodynamic properties and efficient coolant use while reducing wall thickness deviations by up to 601% compared to 3D designs, enhancing engine efficiency and cooling performance.
Implementation Method 1
Differential thermal expansion between a mold provided to generate the outer airfoil geometry and a core provided to generate the internal cooling channels result in comparatively large wall thickness tolerances
Data Source
AI summary
Disclosed is a cooled airfoil having a hub end and tip, an airfoil height being defined between the hub end and the tip. The airfoil has a leading edge, trailing edge, suction side and pressure side. The airfoil has a first airfoil height section adjacent the hub end and extending towards the tip, wherein, in a meridional view, the leading edge and trailing edge are straight along the first airfoil height section. The airfoil has a second airfoil height section adjacent the tip and extending towards the hub end, wherein, in a meridional view, the airfoil is concavely shaped at the leading edge and is convexly shaped at the trailing edge along the second airfoil height section. At least one cooling channel has a length principally extending along the airfoil height, extends straight in a first cooling channel length section, and is bent in a second cooling channel length section.