Metallic Seal Ring Geometry for Dynamic Turbine Sealing
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Solution Overview
Problem
Existing piston seal rings (PSR) in gas turbine engines face challenges in maintaining effective sealing under dynamic and pressure loading conditions, particularly due to their small cross-section and split design, which provide limited hoop strength and twist resistance.
Innovation Solution
A turbine engine rotor design featuring a seal ring with a central axial cross-section that forms a loop and an extension, providing multiple contact points with the groove and outer member, and having an overall axial length that is at least 130% of the loop's axial length, enhancing sealing efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the seal ring has a small cross-section to be compliant, then the seal ring can accommodate small excursions and dynamic loading, but the hoop strength and twist resistance are reduced
Solution Approach 1:
The seal ring cross-section is segmented into multiple regions (first region, second region, third region, fourth region) with different radial spans and contact characteristics. This segmentation allows each region to contribute differently to compliance and strength, resolving the contradiction by distributing functions across segments rather than requiring uniform dimensions throughout the seal ring.
Solution Approach 2:
The seal ring employs an asymmetric cross-sectional design where different regions have different radial spans relative to the groove. The first and second regions have different radial spans than the third and fourth regions, creating an asymmetric structure that optimizes both compliance in certain areas and strength in others, thereby addressing the contradiction between adaptability and strength.
2Ease of manufacture
If the seal ring is split for assembly purposes, then the seal ring can be installed and allow radial expansion, but the hoop strength is reduced
Solution Approach 1:
The seal ring design incorporates local quality variations in the cross-section, with specific regions having optimized radial spans and contact characteristics. This localized optimization compensates for the strength reduction caused by the split, allowing the seal ring to maintain adequate hoop strength in critical areas while preserving assembly advantages.
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 proposed seal ring design effectively accommodates small excursions and dynamic loading conditions, ensuring reliable sealing performance by increasing the axial length and radial span, thereby enhancing the seal's compliance and contact area.
Implementation Method 1
The proposed seal ring design effectively accommodates small excursions and dynamic loading conditions, ensuring reliable sealing performance by increasing the axial length and radial span, thereby enhancing the seal's compliance and contact area.
Data Source
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AI summary
A metallic seal ring has a cross-section of a "6" or "9" shape with an open loop and an extension therefrom. The open loop is seated in a groove (100) of an inner member (98) and, in cross-section has three spaced contact locations (70', 74', 78') with the groove (100) at a first sidewall surface (102), a second sidewall surface (104), and a base surface (106), respectively with gaps between the contact locations (70', 74', 78'). The seal extension has a fourth contact location (72') with an inner surface (110) of an outer member (112) axially beyond a span (LG, L'SB) between the first and second sidewall surface contact locations (74', 78').