Sandwich Composite Airfoil Cellular Core Densification
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Solution Overview
Problem
Ceramic matrix composite (CMC) airfoils for gas turbine engines face challenges in achieving full densification due to the thickness of the preform, leading to partial densification and porosity issues, as the infiltrant materials struggle to flow through thick designs during the densification process.
Innovation Solution
A sandwich composite airfoil design is implemented, featuring a cellular core sandwiched between ceramic fiber ply skins, which allows for thicker walls while ensuring complete densification by providing pathways for the ceramic matrix material to flow through the cellular structure, using materials like honeycomb, foam, or ceramic felt, and optionally filled with monolithic or fibrous ceramic filler materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the preform thickness is increased to achieve thicker wall airfoils, then the mechanical strength and temperature resistance are improved, but the densification completeness deteriorates due to infiltrant material inability to flow through thick designs
Solution Approach 1:
The airfoil preform is segmented into a sandwich composite structure with a cellular core and thin ceramic fiber ply skins. This segmentation allows the infiltrant material to flow through the cellular core structure, achieving complete densification while maintaining thick wall design for mechanical strength and temperature resistance.
Solution Approach 2:
A cellular core structure with porous or open-cell geometry is used as the sandwich composite core. This porous structure provides pathways for infiltrant material flow during densification, enabling complete impregnation even in thick-walled airfoils while maintaining the desired mechanical properties.
2Temperature
If thermal barrier coatings are applied to superalloy airfoils to extend temperature capability, then the temperature resistance is improved, but the device complexity and manufacturing steps increase
Solution Approach 1:
The airfoil is constructed as a ceramic matrix composite (CMC) with a cellular core and ceramic fiber ply skins, inherently providing high temperature resistance without requiring additional thermal barrier coatings. This composite structure achieves temperature capability improvement while avoiding the added complexity of multi-layer coating applications.
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 enables the production of aerodynamically efficient and manufacturable CMC airfoils with thicker walls, eliminating concerns of partial densification and ensuring full densification of the ceramic matrix, thereby enhancing the mechanical properties and performance of the airfoils.
Implementation Method 1
providing pathways for the ceramic matrix material to flow through the cellular structure
Data Source
AI summary
A method for fabricating an airfoil for a gas turbine engine includes providing a core blank made of a cellular material, shaping the core blank into a cellular core, forming a fiber preform that has an airfoil section and a platform by laying-up first and second ceramic fiber ply skins on the cellular core such that in the platform the cellular core is sandwiched radially between the first and second ceramic fiber ply skins, the first and second ceramic fiber ply skins each include at least one 2-D ceramic fiber ply, and densifying the fiber preform with a ceramic matrix.