Multistage Brush Seal Venting for Balanced Last-Stage Pressure Drop
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Solution Overview
Problem
Multistage brush seals in turbomachinery face uneven pressure drop distribution, leading to increased wear and failure of downstream brush seal pieces, which reduces overall sealing performance and reliability and increases maintenance costs.
Innovation Solution
A last-stage pressure drop-adjustable multistage brush seal structure with a stator casing, gears, vent holes, and a brush wire beam that balances inter-stage pressure by transferring torsion moments and controlling gas flow through strategically positioned vent holes, reducing axial pressure drop and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the downstream brush seal piece bears high inter-stage pressure drop to maintain low leakage, then sealing effectiveness is improved, but the brush wires are more likely to be damaged, causing short-term failure
Solution Approach 1:
The vent holes provide beforehand cushioning by creating pressure relief pathways before the downstream brush seal pieces are subjected to excessive pressure. This preventive measure reduces the peak pressure experienced by the brush wires, preventing damage and extending service life while maintaining sealing effectiveness during normal operation.
Solution Approach 2:
The patent changes the pressure distribution parameters by introducing vent holes that modify the inter-stage pressure differential. This parameter change reduces the excessive pressure on downstream brush seal pieces, allowing the brush wires to operate within safe stress limits and extend their service life without compromising sealing performance.
2Reliability
If vent holes are added to balance pressure drop, then downstream brush seal reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the stator casing by introducing discrete vent holes at specific locations. This segmentation approach allows pressure relief to be achieved through simple, localized modifications rather than complex overall structural changes. The vent holes are strategically positioned to target specific high-pressure zones, providing effective pressure balance with minimal added complexity.
Solution Approach 2:
The vent holes represent a simple, low-cost structural modification compared to more complex pressure balancing mechanisms. By using simple hole features rather than complex mechanical components, the patent achieves pressure balance with minimal impact on device complexity and manufacturing cost.
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 solution effectively balances pressure drop across the multistage brush seal, enhancing reliability, durability, and reducing maintenance costs by controlling vent amount and leakage, ensuring long-term stable operation.
Implementation Method 1
when the rotor occurs the instantaneous radial migration, elastic yielding will be produced by the flexibility of brush wires
Implementation Method 2
When the rotor is restored from an eccentric position, the brush wires will follow the rotor in time under the action of elastic restoring force
Implementation Method 3
The downstream brush seal piece vent through holes are formed in the upper side of the downstream brush seal piece and are communicated with the stator casing vent holes to connect upstream gas with downstream gas of the downstream brush seal piece
Data Source
AI summary
A last-stage pressure drop-adjustable multistage brush seal structure. The seal structure comprises a stator casing, gears, gear shafts, stator casing vent holes, a brush wire beam, downstream brush seal piece vent through holes, downstream brush seal upper side gear teeth, and the like. The stator casing is stationary. An upstream brush seal piece is fixedly mounted on the inner side of the stator casing. According to the last-stage pressure drop-adjustable multistage brush seal structure, reverse driving force moment in an inclined direction of brush wires is given to the gear shafts, torsion moment is transferred to the gears through the gear shafts, and the downstream brush seal piece gear teeth are engaged with the downstream brush seal piece and transfer the torsion moment to the downstream brush seal piece, such that the downstream brush seal piece rotates around a rotor.