Floating Brush Seal Assembly for Rotor Excursion and Bristle Wear
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Solution Overview
Problem
Conventional seal assemblies in gas-turbine engines, such as carbon and labyrinth seals, experience oil leakage issues, leading to imbalance and safety risks, while brush seals offer better sealing but result in unacceptable wear due to bristle interference and thermal growth.
Innovation Solution
A floating brush seal assembly with a radially elastic bristle holder and axial and radial springs that allow for excursion absorption without bristle damage, combined with friction-reducing coatings and anti-rotation features to maintain a robust seal and reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brush seals are used to improve sealing performance, then sealing efficiency is improved, but bristle wear increases to unacceptable levels
Solution Approach 1:
The bristle holder is made radially elastic to allow dynamic movement during rotor excursions. This enables the brush seal to float and absorb radial movements without transferring excessive wear forces to the bristles, resolving the contradiction between maintaining sealing contact and reducing bristle wear.
Solution Approach 2:
The invention changes the mechanical properties of the bristle holder by making it radially elastic rather than rigid. This parameter change allows the holder to deform and absorb excursion forces, protecting the bristles from damage while maintaining sealing effectiveness.
2Stability of the object's composition
If rigid bristle holder is used to maintain seal position, then sealing stability is improved, but wear during rotor excursion increases
Solution Approach 1:
The radially elastic bristle holder provides dynamic stability rather than rigid stability. It can move with rotor excursions to maintain optimal bristle contact while absorbing harmful forces, preventing bristle damage during transient conditions.
Solution Approach 2:
The elastic bristle holder acts as a cushioning element that anticipates and absorbs excursion forces before they reach the bristles. This beforehand cushioning protects the bristles from damage during rotor excursions while maintaining seal stability.
3Reliability
If axial spring force is increased to improve sealing contact, then sealing efficiency is improved, but friction force increases reducing brush seal performance
Solution Approach 1:
The invention optimizes the axial spring force parameter to achieve the minimum necessary contact pressure for effective sealing. By carefully selecting the spring constant and pre-load, the seal maintains adequate contact while minimizing friction forces that would otherwise damage the bristles.
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 floating brush seal assembly effectively minimizes oil leakage, reduces wear on bristles, and maintains a centered position during rotor excursions, enhancing sealing efficiency and safety by balancing spring and friction forces with excursion forces.
Implementation Method 1
an axial spring configured to apply an axial force to the brush seal
Implementation Method 2
a radial spring configured to apply a radial force to the brush seal
Implementation Method 3
a friction reducing coating is provided at points of contact between the bristle holder and the backing plate
Data Source
Figure 1
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Figure 3
AI summary
A floating brush seal assembly includes a ring-shaped housing (34) defining a radially inwardly open internal cavity (36); a brush seal (38) in the cavity (36) and having bristles (42) extending radially inwardly and offset to seal against a rotating body (44); a radial spring (56) positioned to exert a radial inwardly directed force against the brush seal (38) relative to the housing (34); and an axial spring (58) positioned to exert an axially directed force against the brush seal (38) relative to the housing (34).