Face Seal Assembly With Damping Elements for Rub-Free Turbomachinery
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Solution Overview
Problem
Designing a seal for turbomachines where the center of fluid pressure always passes through the geometrical center is challenging, leading to pressure moment coupling between radial and axial vibrations. This causes significant reduction in axial gap, catastrophic rubs, and increased wear, limiting the seal's useful life.
Innovation Solution
Incorporating tuned mass damper elements into the face seal ring design, with features on the seal slider to accommodate circumferential mass segments, spring, and damper elements in both axial and radial directions. This maintains the seal centered radially and isolates it from radial vibrations, preventing rubs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional seal design is used, then the seal structure is simple, but radial vibrations cause pressure moment coupling leading to reduced axial gap and catastrophic rubs
Solution Approach 1:
A damping element is introduced as an intermediary component between the seal ring and the stator. This damping element absorbs radial vibrations and prevents them from coupling with the fluid pressure, thereby eliminating the harmful pressure moment coupling while maintaining seal reliability. The damping element acts as a mediator that isolates the seal from vibrational disturbances.
Solution Approach 2:
The damping element provides beforehand cushioning by being pre-installed in the seal assembly to counteract radial vibrations before they can cause catastrophic rubs. The damping element is positioned in advance to absorb and dissipate vibrational energy, preventing the coupling between radial and axial vibrations that would otherwise lead to seal failure.
2Duration of action of stationary object
If damping elements are added to reduce radial vibrations, then wear is reduced and useful life is extended, but the seal structure becomes more complex
Solution Approach 1:
The damping element is segmented into multiple independent damping structures distributed around the seal assembly. Each segment independently absorbs radial vibrations, and the segmented design allows for easier integration into the existing seal structure without requiring complete redesign. This segmentation approach extends seal life while minimizing the increase in overall structural complexity.
Solution Approach 2:
The damping element utilizes flexible damping material that can be integrated as a thin film or shell within the seal assembly. This flexible structure absorbs radial vibrations effectively while occupying minimal space and adding little structural complexity. The thin film damping element maintains the seal's original compact design while providing vibration protection.
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 introduction of damping elements allows for reliable, rub-free operation of the seal even under significant radial vibrations of the stator, extending the seal's useful life by reducing wear and maintaining the axial gap.
Implementation Method 1
at least one damping element arranged with the ring carrier for maintaining the seal assembly centrally in a radial direction in the turbomachine
Implementation Method 2
the at least one damping element comprises at least one spring element and at least one mass element
Data Source
AI summary
A seal assembly for a turbomachine includes a rotating component, a non-rotating component having a ring carrier, a face seal ring, and a joint disposed between the ring carrier and the non-rotating component. The non-rotating component is arranged with the rotating component at a sealing interface. The joint is capable of linear and tilt displacement to allow the non-rotating component to displace with respect to the rotating component. The sealing interface defines a gap between the face seal ring and the rotating component. The seal assembly also includes at least one damping element arranged with the ring carrier for maintaining the seal assembly centrally in a radial direction in the turbomachine. Further, the damping element(s) includes at least one mass element.