Vane Airfoil Assembly Radial Tabs Thermal Mismatch
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Solution Overview
Problem
Gas turbine engine vanes face challenges in thermal expansion mismatch between ceramic matrix composite (CMC) airfoil pieces and metallic spar pieces due to differing thermal expansion rates, leading to heat conduction and increased temperature gradients, particularly at radially inner and outer ends.
Innovation Solution
A vane airfoil assembly featuring a hollow airfoil section with a collar projection and radial tabs that interact with a metallic spar piece, where the collar projection extends past the airfoil platforms and includes radial tabs to transfer structural loads and minimize heat conduction by providing additional surface area for load transfer while reducing heat conduction surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a CMC airfoil piece is joined to a metallic spar piece, then the airfoil achieves high temperature resistance and oxidation resistance, but thermal expansion mismatch causes heat conduction and increased temperature gradients
Solution Approach 1:
The collar projection acts as an intermediary element between the CMC airfoil piece and the metallic spar piece. It provides a transition zone that manages the thermal expansion mismatch between the two materials, reducing heat conduction from the hot airfoil to the cooler spar while maintaining structural integrity.
Solution Approach 2:
The invention uses a composite structure combining CMC material for the airfoil piece with a metallic spar piece. The CMC provides high-temperature resistance and oxidation resistance, while the metallic spar provides structural support. The collar projection bridges these two different material systems to manage their incompatible thermal properties.
2Strength
If the collar projection provides load transfer surface area, then structural loads are effectively transferred, but heat conduction increases due to larger contact area
Solution Approach 1:
The collar projection features radial tabs that concentrate load transfer at specific localized areas rather than distributing it uniformly across the entire collar surface. This localizes the mechanical interaction to discrete points (the tabs) while minimizing the overall heat conduction path between the airfoil and spar.
Solution Approach 2:
The radial tabs extend in a radial direction from the collar projection, adding a dimensional element that optimizes load transfer geometry. This radial arrangement allows efficient force transmission from the tangential loads to the axial spar while maintaining minimal thermal contact area.
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 effectively manages thermal expansion mismatch and reduces temperature gradients by transferring structural loads through radial tabs, enhancing the durability and thermal performance of the vane assembly.
Implementation Method 1
thermal expansion mismatch between ceramic matrix composite (CMC) airfoil pieces and metallic spar pieces due to differing thermal expansion rates
Implementation Method 2
leading to heat conduction and increased temperature gradients
Data Source
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AI summary
An airfoil piece includes a first vane platform (66), a second vane platform (68), and a hollow airfoil section (70) that joins the first vane platform (66) and the second vane platform (68). The hollow airfoil section (70) includes a collar projection (74) which extends past the first vane platform (66). The collar projection (74) includes at least one radial tab (75) projecting therefrom. An airfoil assembly and a method of assembling a vane are also disclosed.