Vane Arc Segment Radial Flanges for CMC Stress Management
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Solution Overview
Problem
Implementing ceramic matrix composite (CMC) materials in gas turbine engine airfoils is challenging due to unique material stress and thermal limitations, requiring a suitable support scheme that avoids concentrating stresses and maintains manufacturability.
Innovation Solution
The use of flanges on airfoil fairings, specifically first, second, and third flanges, which serve as exclusive support features to transmit tangential, axial, and radial loads to support hardware, facilitating a low-stress mounting scheme and maintaining aerodynamic efficiency while being manufacturable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic matrix composite materials are used in airfoils to achieve high temperature resistance, then temperature capability is improved, but manufacturing complexity and stress management difficulty increase
Solution Approach 1:
The airfoil is divided into distinct functional zones: the airfoil section maintains aerodynamic shape while the platforms provide structural support. The flanges are segmented to specifically handle different load directions (radial, tangential, axial), allowing each component to be optimized for its specific function while simplifying the overall support scheme.
Solution Approach 2:
The flanges act as intermediary elements between the airfoil section and the support hardware. These intermediate structures transmit and distribute stresses from the aerodynamic loads to the support system, protecting the CMC airfoil material from direct stress concentration while maintaining the high temperature resistance benefit.
2Strength
If flanges are added to transmit aerodynamic loads to support hardware, then load transmission capability is improved, but structural complexity increases
Solution Approach 1:
The flanges are designed to perform multiple functions simultaneously: they transmit radial loads, tangential loads, and axial loads; they provide attachment surfaces for support hardware; and they distribute stresses to prevent concentration. This multi-functionality reduces the need for separate components, simplifying the overall structure despite the added complexity of the flange features themselves.
Solution Approach 2:
The flanges are positioned and dimensioned to specifically address stress distribution in critical locations. The radial flanges handle circumferential stresses while the axial flanges manage longitudinal loads, with each feature's geometry optimized for its specific load transmission function, thereby improving overall strength without uniformly increasing structural complexity throughout the entire airfoil.
3Reliability
If exclusive flanges are used as support features, then stress concentration is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The flanges are designed with uniform radial height and consistent geometry across all platforms, creating equipotential attachment surfaces for the support hardware. This standardized approach ensures uniform stress distribution while simplifying manufacturing by using repeated geometries rather than custom-shaped flanges for each platform, thereby reducing precision requirements.
Data Source
AI summary
A vane arc segment includes an airfoil fairing that has first and second platforms and an airfoil section. The platforms have first and second openings that open into the airfoil section. The platforms each define first and second circumferential mate faces, forward and aft sides, a gaspath side, a non-gaspath side. The first platform has a first flange that projects radially from the non-gaspath side aft of the first opening and a second flange that projects radially from the non-gaspath side forward of the first opening. The first and second flanges are exclusive flanges on the first platform. The second platform has a third flange that projects radially from the non-gaspath side aft of the second opening.