Multi-Plane Brush Seal Structure for Bristle Deflection Control
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Solution Overview
Problem
Brush seals in turbine engines face challenges in maintaining effective sealing in high pressure difference and turbulent air environments, as bristles can flutter or deflect, compromising their sealing ability.
Innovation Solution
A multi-plane annular brush seal design with bristles having distinct lengthwise portions, where the first and third portions are parallel to different planes skewed by an obtuse angle, and the back plate supports the bristles through a transition region, providing enhanced stability and windage protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bristles are used to seal the gap between members, then sealing ability is improved, but bristles can flutter or deflect in turbulent air flow and high pressure difference environments, compromising sealing performance
Solution Approach 1:
The bristle is divided into three distinct lengthwise portions (first, second, and third portions) with different orientations. The first portion extends parallel to a first plane, the second portion is disposed between the first and third portions, and the third portion extends parallel to a second plane that is skewed from the first plane by an obtuse angle. This segmentation allows each portion to independently respond to different forces, preventing overall bristle deflection while maintaining sealing contact.
Solution Approach 2:
The invention transitions from a conventional single-plane bristle configuration to a multi-plane configuration where bristles extend across two skewed planes. By orienting the first and third portions of each bristle parallel to different planes that are skewed by an obtuse angle, the bristle structure gains dimensional complexity that enables it to resist forces from multiple directions simultaneously, thereby maintaining stability in turbulent and high-pressure environments.
2Adaptability or versatility
If bristles are canted at an angle in the direction of rotation to accommodate transient movement, then adaptability is improved, but bristles can still migrate out of position due to turbulent air flow and pressure differences
Solution Approach 1:
The bristle is segmented into three portions with specific orientations: the first portion parallel to a first plane, the second portion between them, and the third portion parallel to a second skewed plane. This segmentation allows the bristle to accommodate transient radial movements through its multi-plane geometry while the back plate's transition region constrains the second portion to prevent excessive migration, thereby maintaining sealing performance in turbulent conditions.
Solution Approach 2:
The back plate with its transition region acts as an intermediary structure that supports the second portion of the bristle. This intermediate support prevents the bristle from migrating out of position due to turbulent air flow and pressure differences, while still allowing the first and third portions to maintain their sealing function against the rotating member surface.
3Reliability
If pressure difference across the seal is increased to improve sealing force, then sealing effectiveness is improved, but bristles deflect under the pressure load, negatively affecting sealing ability
Solution Approach 1:
The bristle is segmented into three portions oriented in different directions. The first portion extends parallel to a first plane, the second portion is disposed between them, and the third portion extends parallel to a second plane skewed by an obtuse angle. This multi-directional segmentation distributes the pressure load across different portions of the bristle, preventing concentrated stress and deflection while maintaining sealing effectiveness.
Solution Approach 2:
Different portions of the bristle have different local qualities in terms of orientation and support. The first portion is supported by the front plate, the second portion is supported by the back plate's transition region, and the third portion is oriented to contact the rotating member surface. This local differentiation allows each portion to optimally resist forces in its specific orientation, enhancing overall bristle strength against pressure-induced deflection.
Data Source
AI summary
A multi-plane annular brush seal is provided. The brush seal includes a plurality of bristles attached to a front plate and a back plate. The back plate has a BP base end, a first BP inner side surface, a BP transition surface, a second BP inner side surface, and a BP tip end. The first BP inner side surface extends from the BP base end to the BP transition surface, and the second BP inner surface extends from the BP transition surface to the BP tip end. At any given circumferential position of the brush seal, the first BP inner side surface extends substantially parallel to a first plane, and the second BP inner side surface extends substantially parallel to a second plane. The first plane is skewed from the second plane by an obtuse angle.