Segmented Finger Seal Assembly for Turbine Seal Intersection Leakage
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Solution Overview
Problem
Finger seal assemblies in gas turbine engines experience significant undesired leakage at the intersection of individual seals due to thermal and pressure-induced deflections, leading to inefficiencies in sealing between static and dynamic components.
Innovation Solution
A seal assembly design incorporating a first and second finger seal assembly with offset slots, secured by an arc-shaped segment finger seal assembly, utilizing joining strips to overlap seams and prevent leakage, formed from corrosion-resistant materials like nickel chromium, allowing for flexible sealing across varying operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional finger seal assemblies are used with intersecting seals, then sealing is provided between components, but significant undesired leakage occurs at the intersection of individual seals due to thermal and pressure-induced deflections
Solution Approach 1:
The seal assembly is divided into multiple separate seal segments (first seal segment, second seal segment, third seal segment) arranged in series around the bypass duct, eliminating the problematic intersection points where leakage occurs. Each segment is a discrete component that can be independently positioned and secured, preventing the leakage issue that arises when seals intersect in traditional designs.
Solution Approach 2:
Joining strips are introduced as intermediary elements between adjacent seal segments to maintain sealing continuity without creating intersection points. These joining strips overlap with the seal segments and provide a bridging mechanism that prevents leakage at the interfaces between segments, solving the problem of leakage at intersections while maintaining the benefits of segmented construction.
2Reliability
If multiple layers of thin sheet metal are nested to form finger seal assemblies, then sealing between static and dynamic components is achieved, but geometric tolerances and operational deflections reduce sealing effectiveness
Solution Approach 1:
The seal segments are designed with inherent flexibility, allowing them to dynamically adapt to thermal and pressure-induced deflections during operation. The segmented construction with joining strips enables the seal assembly to flex and maintain contact with the mating surfaces despite geometric tolerances and operational deflections, maintaining sealing effectiveness under varying conditions.
Solution Approach 2:
The seal segments are constructed from flexible materials (thin sheet metal layers) that can deform to accommodate geometric tolerances and thermal expansion. This flexibility allows the seals to maintain effective contact with the bypass duct and rotor assembly surfaces despite manufacturing variations and operational deflections, ensuring reliable sealing.
3Reliability
If seal assemblies are designed to accommodate thermal and pressure-induced deflections, then sealing effectiveness is maintained under varying conditions, but device complexity increases
Solution Approach 1:
The seal assembly is divided into multiple discrete segments that can be independently manufactured and assembled, simplifying the overall design while accommodating deflections. Each segment is a relatively simple component that can flex independently, and the modular construction reduces the complexity of designing a single complex seal structure capable of handling all deflection scenarios.
Solution Approach 2:
Joining strips serve as simple intermediary elements that connect seal segments while accommodating relative movement and deflection. These joining strips add minimal complexity to the overall assembly while effectively maintaining sealing continuity under thermal and pressure-induced deflections, providing a simple solution to a complex problem.
Data Source
Figure 1
Figure 1A
Figure 2~2B
AI summary
A seal assembly (70) for a gas turbine engine, including: a first finger seal assembly (72), the first finger seal assembly including two layers (96, 98) each being secured to each other, the two layers each having a plurality of slots (100) that are offset from each other when the two layers of the first finger seal assembly are secured to each other; a second finger seal assembly (74), the second finger seal assembly including two layers (96, 98) each secured to each other, the two layers each having a plurality of slots (100) that are offset from each other when the two layers of the second finger seal assembly are secured to each other; and an arc-shaped segment finger seal assembly (104) located between the first finger seal assembly (72) and the second finger seal assembly (74), the arc-shaped finger seal assembly including two layers (96, 98) each secured to each other, the two layers each having a plurality of slots (100) that are offset from each other when the two layers of the arc-shaped finger seal assembly are secured to each other.