3-D CMC Turbine Airfoil Integral Textile Structure
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Solution Overview
Problem
Ceramic matrix composite (CMC) structures for turbine airfoils face limitations in through-thickness strength and susceptibility to delamination, especially at sharp trailing edges, and conventional methods for forming cooling holes damage the reinforcing fibers, leading to strength loss.
Innovation Solution
A 3-D fiber architecture with an integral textile structure featuring a top and bottom wall made from an angle-interlock weave, where the warp and weft fiber tows are radial and circumferential, respectively, and the weft tows are interlocked through the thickness to inhibit delamination, allowing for thin trailing edges and integrated cooling channels without the need for machining or drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multi-ply 2-D layups of reinforcing fibers are used, then the airfoil structure can be manufactured, but the through-thickness strength is low and delamination susceptibility increases
Solution Approach 1:
The patent transitions from conventional 2-D fabric layups to a 3-D woven architecture where fibers are interlaced in three dimensions. This dimensional change allows fibers to traverse through the thickness of the airfoil structure, creating interlocking patterns that mechanically bond layers together and prevent delamination while maintaining manufacturing feasibility
Solution Approach 2:
The patent employs a composite fiber architecture combining organic fibers (such as carbon or glass) with a ceramic matrix material. This composite structure provides both the mechanical strength of the organic fibers and the high-temperature stability of the ceramic matrix, enabling the airfoil to withstand extreme thermal and mechanical conditions while maintaining structural integrity
2Ease of manufacture
If laser drilling is used to form cooling holes, then cooling channels can be created, but reinforcing fibers are destroyed and strength is lost
Solution Approach 1:
The patent incorporates cooling channels directly into the 3-D woven fiber preform before the final ceramic matrix infiltration process. By pre-forming the cooling channel pathways as void spaces within the fiber architecture, the need for subsequent laser drilling is eliminated, preserving the integrity of the reinforcing fibers and maintaining the composite's strength while still providing effective cooling functionality
Solution Approach 2:
The cooling channels are nested within the 3-D fiber structure during the preform fabrication stage. The fiber tows are arranged and woven around predefined channel pathways, creating a nested configuration where the cooling channels are embedded within the structural matrix. This integrated approach allows cooling functionality to be incorporated without compromising the load-bearing fiber network
3Shape
If thin trailing edges are designed, then aerodynamic performance is improved, but structural integrity and resistance to delamination decrease
Solution Approach 1:
The 3-D woven architecture enables thin trailing edges by distributing structural reinforcement throughout the thickness direction rather than relying on stacked 2-D plies. The interlaced fiber pattern creates a mechanically interlocked structure that maintains strength even when the overall thickness is reduced, allowing aerodynamically optimal thin trailing edges without sacrificing structural integrity
Data Source
AI summary
An integral textile structure for 3-D CMC turbine airfoils includes top and bottom walls made from an angle-interlock weave, each of the walls comprising warp and weft fiber tows. The top and bottom walls are merged on a first side parallel to the warp fiber tows into a single wall along a portion of their widths, with the weft fiber tows making up the single wall interlocked through the wall's thickness such that delamination of the wall is inhibited. The single wall suitably forms the trailing edge of an airfoil; the top and bottom walls are preferably joined along a second side opposite the first side and parallel to the radial fiber tows by a continuously curved section in which the weave structure remains continuous with the weave structure in the top and bottom walls, the continuously curved section being the leading edge of the airfoil.