Airfoil Impingement Cooling With Curved Flex Elements for Thermal Fatigue
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Solution Overview
Problem
Turbomachine hot gas path components face challenges with thermally driven low cycle fatigue (LCF) due to high temperature exposure, particularly when additively manufactured with complex cooling schemes, which also increase manufacturing costs and complexity.
Innovation Solution
An airfoil design with an impingement cooling structure featuring a spaced impingement wall and flex elements with multi-dimensional curvature, allowing for strain relief and efficient cooling, manufactured integrally through additive processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If complex cooling schemes with small cooling passages are used, then cooling efficiency is improved, but fabrication difficulty and manufacturing cost increase
Solution Approach 1:
The cooling structure is divided into multiple discrete cooling elements arranged in an array, where each element contains cooling passages. This segmentation allows for standardized manufacturing of individual elements that can be assembled into the final component, reducing overall fabrication difficulty while maintaining complex cooling functionality.
Solution Approach 2:
The cooling passages are nested within the cooling elements, with internal cooling channels integrated into the structural components themselves. This nesting approach allows complex cooling geometry to be incorporated without adding external complexity, enabling efficient cooling while maintaining manufacturability through additive manufacturing processes.
2Device complexity
If additively manufactured hot gas path components are used, then complex cooling features are achieved, but thermally driven low cycle fatigue increases
Solution Approach 1:
The cooling elements incorporate localized structural variations with different geometries and cooling passage configurations optimized for specific thermal loading conditions. This local quality approach allows the structure to better distribute thermal stresses and reduces hot spots that would otherwise initiate fatigue cracks, thereby improving low cycle fatigue resistance while maintaining complex cooling features.
Solution Approach 2:
The cooling elements are manufactured using additive manufacturing processes that enable integration of multiple materials or graded material properties within single components. This composite approach allows optimization of material properties in different regions to simultaneously achieve complex cooling geometry and improved fatigue resistance through controlled material microstructure and property gradients.
3Ease of manufacture
If traditional cooling structures are used, then manufacturing is simpler, but strain relief and fatigue resistance are reduced
Solution Approach 1:
The cooling elements incorporate flexible or compliant features that allow for thermal expansion and strain relief during thermal cycling. These dynamic features enable the structure to accommodate thermal deformations without generating excessive stresses that would lead to fatigue failure, while still maintaining relatively simple manufacturing 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
The design enhances strain resistance and reduces thermally induced fatigue, enabling cost-effective manufacturing and operation at higher temperatures with improved durability and reduced assembly costs.
Implementation Method 1
a first flex element may include a main portion extending at a first angle along the impingement wall, a terminal portion extending at a second angle along the impingement wall that is different than the first angle, and an arcuate portion extending between the main portion and the terminal portion
Implementation Method 2
air, typically bleed air from the compressor section, is forced through internal cooling passages within the airfoil and then discharged through cooling holes at the airfoil surface to transfer heat from the hot gas path component
Implementation Method 3
at least one flex element of the plurality of flex elements include a main portion extending at a first angle along the impingement wall, a terminal portion extending at a second angle along the impingement wall that is different than the first angle, and an arcuate portion extending between the main portion and the terminal portion
Data Source
AI summary
An airfoil includes an airfoil body having a leading edge, a trailing edge, a suction side, and a pressure side. The airfoil body extends in a radial direction between a base end and a tip end, and the airfoil body defines a chamber. The airfoil further includes an impingement cooling structure positioned within the chamber. The impingement cooling structure includes an impingement wall that is spaced apart from the airfoil body such that a post-impingement cavity is defined between the impingement wall and the airfoil body. The impingement cooling structure further includes a plurality of flex elements that each extend from the impingement wall towards the chamber. At least one flex element of the plurality of flex elements include a main portion, a terminal portion, and an arcuate portion extending between the main portion and the terminal portion.