Composite Labyrinth Seal Rings for Rotor Rubbing Damage
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Solution Overview
Problem
Rotary machines face issues with sealing efficiency due to thermal expansion and centrifugal forces, leading to potential damage from rubbing between rotor and stator components, especially when the sealing gap is too small, and existing resilient sealing segments are not effective in preventing major damage.
Innovation Solution
The labyrinth seal design incorporates sealing rings made of a softer material, such as aluminum alloys, with a narrow connecting surface to the base material, which has a higher rigidity, and includes a solid lubricant like graphite or α-boron nitride to minimize abrasion, and an adhesion-promoting intermediate layer for a durable connection, ensuring the sealing rings are easier to repair or replace than the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If sealing rings are made of soft material to reduce rubbing damage, then ease of repair is improved, but thermal expansion compatibility deteriorates
Solution Approach 1:
The sealing rings are made of composite construction with a soft outer layer (aluminum alloy or polymer) for rubbing protection and a rigid inner layer (steel) for structural integrity and thermal expansion compatibility. This composite structure allows the soft material to absorb rubbing damage while the rigid core maintains dimensional stability under thermal and centrifugal loads.
Solution Approach 2:
Different regions of the sealing ring have different material properties: the outer surface facing the rotor is made soft for rubbing resistance, while the inner region connected to the base is made rigid for thermal stability. This local differentiation allows each region to perform its specific function optimally.
2Reliability
If sealing rings are made of soft material to absorb rubbing damage, then reliability is improved, but rigidity deteriorates
Solution Approach 1:
The sealing rings combine soft outer material (aluminum alloy or polymer) for rubbing damage absorption with a rigid inner material (steel) for structural strength. This composite construction allows the soft outer layer to deform and absorb rubbing impacts while the rigid inner layer maintains overall structural integrity and prevents excessive deformation.
3Reliability
If connecting surface between base and sealing rings is made narrow to reduce thermal stress, then thermal expansion compatibility is improved, but manufacturing precision deteriorates
Solution Approach 1:
An intermediate layer is introduced between the base and the sealing rings to act as a transition zone. This intermediate layer accommodates the thermal expansion differences between the base and sealing rings, reducing thermal stresses while providing a sufficient bonding surface area for reliable attachment. The intermediate layer effectively mediates the conflicting requirements of narrow connection for thermal stress reduction and adequate surface area for manufacturing precision.
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
This design reduces rubbing damage by allowing the softer sealing rings to absorb deformation, minimizing material removal and maintenance needs, while maintaining a strong and durable connection between materials, thus preventing rotor distortion and maintaining efficiency.
Implementation Method 1
allowing the softer sealing rings to absorb deformation, minimizing material removal
Implementation Method 2
includes a solid lubricant like graphite or α-boron nitride to minimize abrasion
Implementation Method 3
an adhesion-promoting intermediate layer for a durable connection
Implementation Method 4
sealing rings which are molded onto the base and protrude into a sealing area, forming labyrinth valleys between them
Data Source
Figure 1
AI summary
The invention relates to a labyrinth seal (2) for sealing a sealing region between a rotor (6) and a stator (8) of a rotary machine, comprising a base (16) and sealing rings (18) integrally molded on the base (16) and protruding into the sealing region. The sealing rings form labyrinth valleys (24) therebetween, which are delimited laterally by the sealing rings (18) and at the bottom of the valley (22) by the base (16). In order to minimize rubbing against the rotor, at least one section of the sealing rings (18) consists of at least one material (28) that is different than the base (16).