Seal Segment Structure for Floating Seals With Flutter Resistance
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Solution Overview
Problem
The existing shaft seal devices in rotary machines face challenges in restricting the flow of thin plate seal pieces in divided portions, leading to reduced floating performance and potential fluttering of the seal pieces.
Innovation Solution
The implementation of a seal segment design with second thin plate seal pieces having greater rigidity, thickness, or length than the first thin plate seal pieces, strategically positioned to enhance fluttering resistance and maintain floating characteristics, includes a structure where the number and thickness of second thin plate seal pieces can be adjusted to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thin plate seal pieces are made thinner to improve floating characteristics, then the floating performance is enhanced, but the fluttering resistance is reduced
Solution Approach 1:
The patent applies different plate thicknesses to different portions of the seal body. Specifically, the end portions (circumferential ends) have a first plate thickness optimized for fluttering resistance, while the intermediate portions have a second plate thickness optimized for floating characteristics. This local differentiation allows each region to perform its intended function without compromising the other.
Solution Approach 2:
The seal body is segmented into multiple thin plate seal pieces arranged in series. Each piece can have different thickness characteristics, allowing the overall seal to exhibit both fluttering resistance (from the end portions) and floating characteristics (from the intermediate portions) simultaneously.
2Stability of the object's composition
If the plate thickness is increased to enhance fluttering resistance, then the stability is improved, but the floating characteristics are degraded
Solution Approach 1:
The patent implements local quality by assigning different thickness values to different spatial locations within the seal body. The end portions use thicker plates for stability, while the intermediate portions use thinner plates for floating performance. This resolves the contradiction by making the thickness a spatially varying property rather than a uniform one.
3Reliability
If the thin plate seal pieces are made longer in the radial direction to improve sealing, then the sealing efficiency is enhanced, but the fluttering occurs more easily
Solution Approach 1:
The patent applies local quality by differentiating the radial length of thin plate seal pieces at different locations. The end portions have a first radial length that provides adequate sealing while maintaining fluttering resistance, while the intermediate portions have a second radial length optimized for sealing efficiency. This spatial differentiation resolves the contradiction between sealing performance and fluttering resistance.
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
This design effectively suppresses performance deterioration and fluttering of thin plate seal pieces, ensuring improved sealing efficiency and longevity by enhancing rigidity and adjusting plate thickness and length to maintain optimal floating characteristics.
Implementation Method 1
a flow in which the thin plate seal pieces easily float
Data Source
Figure 1
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Figure 3
AI summary
A seal segment (11) includes a retainer extending in a circumferential direction (Dc) of a rotary shaft on an outer circumferential side of the rotary shaft; a first seal body (13) which has a plurality of first thin plate seal pieces (20) extending inward in a radial direction (Dr) from the retainer and laminated in the circumferential direction (Dc); a high-pressure side plate (23) and a low-pressure side plate which are supported so as to be sandwiched between the first seal body (13) and the retainer, and cover one side in an axial direction (Da) of the first seal body (13) over the circumferential direction (Dc); and a second seal body (33) having a plurality of second thin plate seal pieces which are laminated at an end portion of the retainer (21) in the circumferential direction (Dc), extend inward in the radial direction (Dr), and have fluttering resistance higher than the first thin plate seal piece (20). The high-pressure side plate (23) and the low-pressure side plate cover at least a part of the second seal body (33) in the circumferential direction (Dc).