Composite Piston Ring Seal for Translating Annular Ducts
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Solution Overview
Problem
Gas turbine engines face challenges in maintaining effective gas-flow stream separation due to varying relative motion between annular cowls, which can cause seals to tear or become ineffective, particularly when the cowl moves diagonally across finger seals.
Innovation Solution
The implementation of a split ring seal system with a composite piston made of glass fiber-reinforced polymer (GFRP) or aramid fiber-reinforced polymer (AFRP) and a bumper bonded to the inner duct, featuring an annular geometry and a spring mechanism to maintain separation between the inner and outer ducts, preventing metal-to-metal contact and ensuring effective sealing during axial and circumferential translation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If finger seals are used to separate gas-flow streams between annular cowls, then gas-flow separation is achieved, but the seals are prone to tearing and becoming ineffective when the cowl moves diagonally across the fingers
Solution Approach 1:
The seal system is divided into multiple circumferential segments (fingers) that can independently deflect and maintain contact. Each finger segment acts as an independent sealing element that can accommodate diagonal movement without compromising the overall seal integrity, preventing the tearing issue associated with rigid continuous seals.
Solution Approach 2:
The finger seals are designed to be flexible and capable of dynamic deflection in response to relative motion between the annular cowls. The fingers can bend and adjust their position to maintain sealing contact even when diagonal movement occurs, transforming the seal from a static rigid structure to a dynamic adaptive system that absorbs movement without failure.
2Reliability
If a piston seal system is implemented to accommodate axial and circumferential translation, then gas-flow separation is maintained, but the device complexity increases with additional components
Solution Approach 1:
The piston seal system performs multiple functions simultaneously: it maintains radial sealing contact between ducts, accommodates axial translation through piston movement, and handles circumferential translation through circumferential flexibility. This multi-functionality reduces the need for separate sealing mechanisms for each type of motion, simplifying the overall system despite the piston structure.
Solution Approach 2:
The piston seal incorporates flexible circumferential elements that can bend and deform to accommodate relative motion between the annular ducts. This flexibility allows the seal to maintain effectiveness during both axial and circumferential translation without requiring complex mechanical joints or multiple sealing components, thereby managing device complexity.
3Weight of moving object
If composite materials are used for the piston instead of metal, then weight is reduced, but wear resistance may be compromised
Solution Approach 1:
The piston is constructed from composite materials that combine the benefits of low density with enhanced mechanical properties. The composite structure provides sufficient wear resistance for the sealing application while maintaining the weight advantage over metal pistons, resolving the contradiction between weight reduction and wear resistance.
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 solution effectively maintains gas-flow stream separation and prevents fluid leaks by using composite materials with favorable wear characteristics and mechanical resistance, ensuring reliable sealing even during movement, while being lighter in weight compared to metal pistons.
Implementation Method 1
A spring may be disposed in the groove. The piston may be configured to bottom in the groove and locate the inner duct separate from the outer duct.
Implementation Method 2
The implementation of a split ring seal system with a composite piston made of glass fiber-reinforced polymer (GFRP) or aramid fiber-reinforced polymer (AFRP)... using composite materials with favorable wear characteristics and mechanical resistance
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A seal system is provided. The seal system may comprise a first duct 14a, 190having an annular geometry, a second duct 14b overlapping the first duct in a radial direction, and a seal disposed between the first duct and the second duct. The seal may comprise a groove 168 defined by the first duct and a piston configured to slideably engage the groove 168.