Brush Seal Pressure Plate Segmentation for Friction Reduction
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Solution Overview
Problem
Existing brush seals in turbomachines face challenges with leakage due to pressure drop-induced bristle deformation and frictional engagement, which limits their effectiveness at higher-pressure differentials and temperatures, and are costly to manufacture with complex pressure balancing features.
Innovation Solution
A circumferentially extending brush seal design featuring a bristle pack with radially extending and circumferentially spaced slots, a pressure plate with grooves that connect inner and outer radial slots for uniform pressure distribution, and a bristle pack backing plate for enhanced support, reducing frictional engagement and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a pressure plate is used to provide lateral support for the bristles on the downstream side, then bristle stiffness is increased, but frictional engagement with the pressure plate increases causing wear and heat generation
Solution Approach 1:
The pressure plate is segmented into multiple regions with different functions: a first region with grooves that allow pressure communication and reduced friction, and a second region that provides lateral support. This segmentation allows the pressure plate to simultaneously reduce frictional engagement while maintaining necessary bristle stiffness.
Solution Approach 2:
Different regions of the pressure plate have different local properties: the first region has grooves that create low-friction zones for pressure balancing, while the second region has a smooth surface that provides lateral support. This local differentiation allows each region to optimize its function without compromising the other.
2Reliability
If multiple grooves are introduced in the pressure plate to balance pressure, then pressure distribution is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The pressure plate is divided into two functional regions: a first region with grooves for pressure balancing and a second region for lateral support. This segmentation achieves pressure balancing with a minimal number of grooves rather than complex multi-groove patterns, reducing manufacturing complexity.
Solution Approach 2:
The pressure balancing function is extracted and concentrated into the first region with grooves, while the lateral support function is assigned to the second region. This separation allows each function to be optimized independently with simpler structures.
3Reliability
If the brush seal is designed to maintain contact with the rotor during operation, then sealing performance is improved, but pressure drop across the bristles causes bristle deformation
Solution Approach 1:
The pressure plate acts as an intermediary between the bristle pack and the downstream low-pressure region. It balances pressure across the bristle pack by allowing pressure communication through grooves in the first region, preventing excessive pressure drop that would cause bristle deformation while maintaining contact with the rotor for sealing.
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 design achieves balanced pressure distribution across the bristle pack, reducing frictional engagement and bristle deformation, enhancing sealing performance and durability while being cost-effective and suitable for high-pressure and temperature applications.
Implementation Method 1
the bristles tend to deform under the influence of the pressure drop... the restoring forces provided by the inherent resilience of the bristles
Implementation Method 2
generally a pressure plate may be used to provide lateral support for the bristles on the downstream side
Implementation Method 3
the pressure drop that exists across the bristle pack may cause the bristles to have a frictional engagement with the face of the pressure plate, and thus increases bristle stiffness and causes wear
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A circumferentially extending brush seal positioned between static 102 and rotary components 104 of a machine and, during operation of the machine, the brush seal 200 having a higher pressure region 106 at an upstream side and a lower pressure region at a downstream side 108. The brush seal 200 may include a plurality of bristles forming a bristle pack 110 carried by the static component 102 and cantilevered toward the rotary component 104 such that tips of at least some of the bristles engage the rotary component 104. The brush seal 200 further may include a pressure plate 114 and a bristle pack backing plate 206. The bristle pack backing plate 206 may include a plurality of radially extending and circumferentially spaced slots 208, 210 opening through opposite sides thereof. The slots 208, 210 may be disposed on an inner radial edge 212 and an outer radial edge 214 of the bristle pack backing plate 206.