Brush Seal Bristle Patterning for Wear and Heat Reduction
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Solution Overview
Problem
Brush seals in gas turbine engines experience wear and heat generation due to pressure differentials, leading to reduced sealing effectiveness over time.
Innovation Solution
An annular brush seal design with varying bristle lengths and a circumferentially repeating pattern, combined with a backing plate featuring radial grooves, to manage pressure differentials and reduce frictional forces, thereby controlling wear rates and enhancing sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform bristle lengths are used in the brush seal, then the seal structure is simple and easy to manufacture, but wear rates increase and sealing effectiveness decreases during initial operation
Solution Approach 1:
The brush seal employs bristles with varying lengths arranged in different patterns (gradual transition, circumferentially repeating, or random distribution) across the sealing face. This local variation in bristle length creates zones with different contact characteristics, reducing initial wear rates and improving sealing effectiveness without requiring complex overall structural changes.
2Reliability
If the bristle pack is subjected to pressure differential forcing tips against the rotor, then sealing effectiveness is maintained, but wear and heat generation increase
Solution Approach 1:
The invention modifies the physical parameters of the bristle pack by implementing non-uniform bristle length distributions. This parameter change alters the contact pressure distribution and friction characteristics, reducing wear rates and heat generation while maintaining the pressure differential sealing mechanism.
3Reliability
If longer bristles are used throughout the sealing face, then sealing effectiveness is improved, but frictional forces and wear increase during initial operation
Solution Approach 1:
The brush seal implements local quality variation by having different bristle lengths in different regions of the sealing face. This creates zones with optimized contact characteristics, reducing frictional forces and wear in high-stress areas while maintaining adequate sealing contact where needed.
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 reduces wear and friction-induced heating, maintaining effective sealing by optimizing hydrodynamic and hydrostatic lift, thus extending the seal's operational lifespan and reducing fuel consumption.
Implementation Method 1
The circumferentially repeating pattern may be configured to generate hydrodynamic lift when the brush seal seals a rotating member such as a shaft of a gas turbine engine.
Implementation Method 2
During operation, a pressure differential across the brush seal may act on the bristles of the brush seal, forcing the tips of the bristles against the adjacent component
Implementation Method 3
The at least one radially extending groove is configured to permit the application of a pressure force between the downstream bristles of the bristle back and the surface of the backing plate facing the bristle pack. This reduces frictional forces acting between the most downstream bristles and the backing plate
Data Source
AI summary
An annular brush seal includes a bristle pack formed of bristles and a bristle pack support, which supports the bristle pack. The bristle pack has an upstream face, a downstream face and a sealing face. The sealing face includes an upstream portion and a downstream portion that is adjacent to the upstream portion. A length of at least a fraction of the bristles of the upstream portion is shorter than a length of the bristles of the downstream portion to form a circumferentially repeating pattern at an interface between the upstream portion of the sealing surface and the upstream surface.