High-Clearance Seal Assembly for Shaft Offset and Low Wear
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Solution Overview
Problem
Shaft offset in turbomachines affects the performance of circumferential seals by increasing friction and wear, as existing seal designs struggle to maintain effective sealing with radial movement and clearance changes.
Innovation Solution
A seal assembly with a housing featuring circumferential pressure grooves and a smooth radial sealing surface, allowing for increased radial clearance while maintaining sealing engagement, reduces frictional forces and wear by distributing pressure evenly across the seal contact surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If radial clearance between shaft and seal is increased, then friction and wear are reduced, but sealing performance deteriorates
Solution Approach 1:
The seal body is divided into multiple segments that can move independently relative to each other. This segmentation allows the seal to adapt to shaft offset conditions while maintaining contact with the shaft surface, thereby reducing friction and wear without compromising sealing performance.
Solution Approach 2:
The seal segments are designed to be dynamically adjustable, allowing them to move radially and axially to maintain optimal sealing contact despite shaft offset. This dynamic adaptation enables the seal to operate effectively with increased radial clearance while preserving sealing integrity.
2Adaptability or versatility
If shaft offset occurs, then radial clearance changes, but sealing effectiveness deteriorates
Solution Approach 1:
The segmented seal structure allows each segment to independently adjust its position in response to shaft offset, maintaining sealing effectiveness despite changes in radial clearance caused by misalignment.
Solution Approach 2:
The seal design incorporates parameters that can change in response to shaft offset, such as segment positioning and contact pressure, allowing the seal to adapt to varying clearance conditions while maintaining sealing effectiveness.
3Object-generated harmful factors
If seal segments are used with lift ramps, then friction is reduced during dynamic operation, but manufacturing complexity increases
Solution Approach 1:
The seal is constructed from separate segments that can be manufactured independently using standard machining processes, avoiding the need for complex integrated lift ramp structures while achieving similar friction reduction through segment movement.
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 solution effectively reduces friction and wear on the seal by allowing increased radial clearance without compromising sealing performance, enhancing the durability and efficiency of the seal assembly.
Implementation Method 1
A seal assembly with a housing having circumferential pressure grooves and a smooth radial sealing surface, allowing for increased radial clearance while maintaining sealing engagement, reduces frictional forces and wear by distributing pressure evenly across the seal contact surface.
Implementation Method 2
Certain circumferential seals include a segmented body having lift ramps formed on the seal inner surface, which cause the segments of the seal to displace radially outwardly during dynamic operation to reduce friction between the shaft and seal.
Data Source
AI summary
A seal assembly includes a seal disposed about a shaft and having an annular body with a radial sealing surface and an inner circumferential sealing surface engageable with the shaft. A housing is disposed about the shaft and has a first inner circumferential surface defining a first annular chamber about the shaft, the seal being disposed within the first annular chamber, a second inner circumferential surface spaced radially inwardly from the first inner circumferential surface and spaced from the outer surface of the shaft by a radial clearance so as to define a second annular chamber. A radial seal contact surface extends between the first and second inner circumferential surfaces and is sealingly engageable by the sealing surface of the seal to prevent flow between the two chambers, and circumferential pressure groove(s) are formed in the seal contact surface and are fluidly coupled with the first chamber.