Bristle-Damped Bellows Seal Assembly for Vibration Control
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Solution Overview
Problem
Carbon face seals in gas turbine engines experience performance degradation due to vibration modes that cause cyclic load variations and excessive stresses, which existing damping solutions, such as metal damping rings, are inadequate in addressing effectively.
Innovation Solution
A seal assembly featuring resiliently flexible bristles that extend from a bristle holder to interface with the bellows, absorbing and damping excessive vibrational frequencies, thereby reducing mechanical stresses and improving operational life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bellows is used to control axial and radial position of the seal nose, then the seal assembly can accommodate axial travel and maintain sealing contact, but the bellows exhibits vibration modes that cause cyclic load variation and excessive stresses
Solution Approach 1:
A damping ring is introduced as an intermediary component between the bellows and the seal nose. This damping ring absorbs and dissipates vibrational energy, reducing the cyclic load variation and excessive stresses transmitted to the bellows and seal assembly, while allowing the bellows to continue accommodating axial travel.
Solution Approach 2:
The vibration modes of the bellows, which were previously harmful causing cyclic load variation and stress, are converted into a beneficial damping effect. The damping ring utilizes the vibrational energy to generate damping forces that counteract the harmful vibrations, transforming the problem into a solution.
2Ease of operation
If a bellows is used to control axial and radial position of the seal nose, then the seal assembly can accommodate axial travel, but the vibration modes negatively impact seal performance due to cyclic load variation
Solution Approach 1:
The damping ring serves as a mediator that isolates the seal nose from the vibrational effects of the bellows. By absorbing vibrations before they reach the seal interface, the damping ring ensures consistent sealing performance and reduces cyclic load variation that would otherwise compromise reliability.
3Object-affected harmful factors
If a metal damping ring with convolutions is used to damp the bellows, then vibration damping is provided, but the damping effectiveness is inadequate for excessive vibrational frequencies
Solution Approach 1:
The damping characteristics are enhanced by modifying the physical parameters of the damping structure. The damping ring incorporates specific geometric features and material properties that optimize its damping capacity across a broader frequency range, making it effective against excessive vibrational frequencies that the conventional metal damping ring could not handle.
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 bristle-based damping solution effectively reduces mechanical stresses and enhances the operational life of the seal assembly and surrounding components by absorbing vibrational frequencies, ensuring effective sealing and load management.
Implementation Method 1
a plurality of bristles that interface with the bellows to damp vibration of the bellows
Implementation Method 2
the plurality of bristles are resiliently flexible
Data Source
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AI summary
A seal assembly (100; 400A; 400B; 400C; 500A; 500B; 500C) includes a seal nose (105), a bellows (110, 410A; 410B; 410C; 510A; 510B; 510C) and a plurality of bristles (120; 420A; 420B; 420C; 520A; 520B; 520C). The seal nose (105) is configured to be in sealing contact with a rotating seal plate (91), the bellows (110, 410A; 410B; 410C; 510A; 510B; 510C) extends between and couples the seal nose (105) to a support structure (109), and the plurality of bristles (120; 420A; 420B; 420C; 520A; 520B; 520C) extends from the support structure (109) toward the bellows (110, 410A; 410B; 410C; 510A; 510B; 510C), with at least one bristle of the plurality of bristles (120; 420A; 420B; 420C; 520A; 520B; 520C) being in contact with the bellows (110, 410A; 410B; 410C; 510A; 510B; 510C) to damp vibration of the bellows (110, 410A; 410B; 410C; 510A; 510B; 510C).