Nested Seal Structure for CMC Vane Arc Segment Leakage Control
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Solution Overview
Problem
Implementing ceramic matrix composite (CMC) materials in gas turbine engine airfoils poses challenges due to unique thermal and structural requirements, particularly in sealing and supporting vane arc segments effectively to maintain pressure and withstand high temperatures.
Innovation Solution
A seal and support system for vane arc segments in a gas turbine engine that includes a vane support arc segment piece with a radially open socket and reaction surfaces to transmit loads, and a seal with disjointed corners and nested seal sections to prevent cooling air leakage, utilizing ceramic materials for thermal buffering and load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are used in airfoils to extend temperature resistance, then high temperature resistance is improved, but sealing and structural support challenges worsen
Solution Approach 1:
The seal is divided into multiple discrete sections (first seal section and second seal section) that can independently conform to the CMC airfoil surface. Each seal section has disjointed corners that allow independent movement and adaptation, ensuring reliable sealing contact with the CMC material while maintaining sealing integrity under thermal expansion and contraction.
Solution Approach 2:
The seal incorporates disjointed corners at specific locations where contact with the CMC airfoil is required, while other portions of the seal maintain structural continuity. This local differentiation allows the seal to adapt to the unique thermal and structural characteristics of CMC materials at the sealing interface while preserving overall seal strength.
2Reliability
If a seal structure is added to maintain pressure in CMC airfoils, then sealing integrity is improved, but device complexity worsens
Solution Approach 1:
The second seal section is nested within the first seal section, with the second seal section positioned to seal the disjointed corners created by the first seal section. This nested arrangement provides multi-layer sealing protection while using a compact, space-efficient structure that minimizes overall complexity.
Solution Approach 2:
Instead of creating a continuous solid seal structure, the design uses disjointed corners with gaps that are sealed by the nested second seal section. This inverted approach of sealing through discontinuities rather than continuity simplifies the overall structure while maintaining effective sealing.
3Adaptability or versatility
If disjointed corners are used in seal sections to conform to CMC surfaces, then adaptability is improved, but manufacturing precision requirements worsen
Solution Approach 1:
The disjointed corners are designed to be flexible and adaptable rather than rigid, allowing each corner to independently conform to the CMC airfoil surface geometry. This dynamic design accommodates thermal expansion and contraction of the CMC material while maintaining sealing contact, reducing the need for extremely tight manufacturing tolerances.
Solution Approach 2:
The seal sections are designed with three-dimensional curvature and depth variations that allow them to conform to the complex geometry of CMC airfoils. By incorporating dimensional variations in multiple directions, the seal can adapt to surface irregularities without requiring ultra-precise manufacturing of each individual feature.
Data Source
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AI summary
A gas turbine engine support system (60) includes a vane arc segment (64), a vane support arc segment piece (62) configured to engage the vane arc segment (64), and a seal (74) disposed radially between the vane arc segment (64) and the vane support arc segment piece (62). The seal (74) includes first and second seal sections (76, 78). The first seal section (76) has a floor wall (76a) and first and second side walls (76b) that project from the floor wall (76a). The first and second side walls (76b) converge to define a disjointed corner (80). The second seal section (78) nests with the first seal section (76) and seals the disjointed corner (80).