Secondary Seal Assembly With Wear Interface for Leakage Control
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Solution Overview
Problem
Current seals in turbomachinery, such as gas turbine engines, face challenges with leakage and wear due to clearance issues and aerodynamic losses, particularly in large and high-pressure systems, where existing seals are not efficient enough to maintain performance and longevity.
Innovation Solution
A seal assembly comprising a primary seal with circumferentially spaced shoes, spring elements, and a secondary seal with a harder material interface to reduce wear and leakage, where the secondary seal acts as a wear component that can be replaced, using materials like cobalt or nickel alloys or coatings like Tribaloy ™, to minimize component wear and maximize seal effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a labyrinth seal is used to seal the circumferential gap, then sealing capability is provided, but radial clearance must be tightly controlled and the seal is sensitive to clearance changes
Solution Approach 1:
A secondary seal made of wear-resistant material is introduced as an intermediary component between the primary seal and the rotating component. This secondary seal acts as a mediator that absorbs wear and protects the primary seal, allowing larger clearances while maintaining sealing effectiveness.
Solution Approach 2:
The invention changes the material parameter of the secondary seal to be harder and more wear-resistant than the primary seal. This parameter change allows the system to tolerate larger clearances and wear without compromising sealing capability.
2Reliability
If clearance between rotating and stationary components is increased to accommodate thermal expansion and shaft motion, then component reliability is improved, but leakage increases and aerodynamic losses worsen
Solution Approach 1:
The secondary seal is designed as a sacrificial, replaceable component that absorbs wear over time. By using a cheaper, harder material for the secondary seal, the system can tolerate larger clearances and more wear without replacing expensive primary seal components, thereby reducing energy losses while maintaining reliability.
Solution Approach 2:
The seal assembly uses composite material strategy with two different materials: a softer primary seal material and a harder secondary seal material. This composite approach allows the secondary seal to protect the primary seal from wear, enabling larger clearances that improve component reliability while the primary seal maintains low leakage.
3Strength
If a harder material is used for the secondary seal interface, then wear resistance is improved, but the secondary seal becomes a replaceable wear component
Solution Approach 1:
The secondary seal is intentionally designed as a sacrificial component made of harder, more wear-resistant material. It is engineered to wear faster than the primary seal, serving as a disposable element that protects more expensive components. This approach improves overall wear resistance while accepting that the secondary seal will need periodic replacement.
4Reliability
If straight-thru labyrinth seals are used, then sealing is provided, but large clearances result in carryover effect and increased vibration
Solution Approach 1:
The secondary seal acts as an intermediary that fills and protects the clearance space between the labyrinth seal and the rotating component. By maintaining better clearance control through the wear-resistant secondary seal, the harmful carryover effect and vibration are reduced while preserving the sealing performance of the labyrinth structure.
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 seal assembly effectively reduces leakage and wear, enhancing the operational efficiency and longevity of turbomachinery components by limiting radial movement and utilizing a replaceable wear component, thus addressing the limitations of existing seals in large and high-pressure environments.
Implementation Method 1
at least one spring element positioned radially outward from the slot in the shoe
Implementation Method 2
A harder material is introduced at the interface of the mid plate and the front plate with the at least one secondary seal
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A seal assembly (10) for sealing a circumferential gap (11) between a first machine component (38) and a second machine component (40) which is rotatable relative to the first machine component 5 (38) about a longitudinal axis (42). The seal assembly (10) includes a seal carrier (36), a primary seal (26), a mid plate (22), at least one secondary seal (14), and a front plate (12). The at least one secondary seal (14) interfaces with the front plate (12) and the mid plate (22). A harder material is introduced at the interface (80) of the mid plate (22) and the front plate (12) with the 10 at least one secondary seal (14), that is made from a more wear resistant material than the other components at the interface (80), to provide the other component/s as a wear component that is replaced more often.