Spring-Biased Vane Face Seal for CMC Airfoil Gap Sealing
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Solution Overview
Problem
Implementing ceramic matrix composites (CMCs) in gas turbine airfoils presents unique challenges due to their high temperature resistance, requiring improved sealing mechanisms to maintain structural integrity and reduce wear.
Innovation Solution
A spring device is integrated into the gas turbine assembly to bias seals, using finger springs that distribute force evenly and stabilize the seal, reducing wear and maintaining proper positioning of airfoil fairings, thereby enhancing the sealing capability of CMC airfoils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are used in airfoils to extend temperature capability, then temperature resistance is improved, but sealing reliability deteriorates due to dimensional variations
Solution Approach 1:
The patent applies parameter changes by introducing a spring device that dynamically adjusts sealing force to compensate for dimensional variations in CMC airfoils. The spring mechanism modifies the contact pressure parameter between seal and airfoil, maintaining reliable sealing despite thermal expansion or contraction of the CMC material.
Solution Approach 2:
The spring device acts as an intermediary element between the seal and the CMC airfoil. It mediates the dimensional variations by providing a compliant mechanical interface that absorbs dimensional changes while maintaining consistent sealing contact, thereby preserving sealing reliability.
2Device complexity
If conventional seal assemblies are used without spring devices, then device complexity is reduced, but seal stability deteriorates leading to increased wear
Solution Approach 1:
The spring device introduces dynamics to the seal assembly by replacing rigid mounting with elastic compliance. The spring fingers can deflect and adapt to dimensional variations, providing dynamic stability to the seal position and reducing wear through controlled motion rather than rigid constraint.
Solution Approach 2:
The spring device provides beforehand cushioning by pre-loading the seal with appropriate contact pressure. This pre-compression cushions the seal against sudden dimensional changes and reduces impact loads during operation, thereby enhancing seal stability and reducing wear.
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 spring device effectively biases seals to compensate for dimensional variations and maintains proper positioning, reducing wear and stress on CMC airfoils, thus improving the sealing efficiency and durability of the turbine components.
Implementation Method 1
a spring device (78) integrated into the gas turbine assembly to bias the seal (76)
Implementation Method 2
The spring device effectively biases seals to compensate for dimensional variations and maintains proper positioning
Data Source
Figure 1
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AI summary
An assembly (60) includes first and second core gaspath walls (66). Each of the core gaspath walls (66) defines a core gas path side (66a) and a non-core gas path side (66b). The first and second core gaspath walls (66) are arranged next to each other and define a gap (G) therebetween. There is a seal (76) arranged on the non-core gas path (66b) side that bridges over the gap (G) to seal (76) the gap. A spring device (78; 178; 278) has a plurality of spring elements (82). The spring elements (82) bias the seal (76) against the non-core gas path sides (66b) of the first and second core gaspath walls (66).