Labyrinth Seal Clearance Profiling to Prevent Tooth Rubbing
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Solution Overview
Problem
Labyrinth seals in gas turbine engines face challenges in maintaining uniform seal clearance due to variations caused by tight fit engagements and temperature gradients, leading to potential rubbing between teeth and seal lands.
Innovation Solution
The design incorporates a labyrinth seal with a rotating component secured to a shaft via a tight fit engagement, featuring teeth with varying clearances where a first clearance is greater than a second, with the first clearance located closer to the engagement location, ensuring consistent seal performance across operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tight fit engagement is used to secure the rotating component to the shaft, then the seal reliability is improved, but the seal clearance becomes non-uniform causing rubbing
Solution Approach 1:
The patent applies local quality by varying the clearance of specific teeth based on their location relative to the tight fit engagement. Teeth closer to the engagement location have greater clearance to accommodate deformation, while teeth farther away maintain smaller clearance. This localized adjustment resolves the contradiction by maintaining uniform effective clearance across all teeth despite the non-uniform deformation caused by tight fit engagement.
2Ease of manufacture
If uniform tooth clearance is designed, then manufacturing is simplified, but thermal expansion and tight fit effects cause rubbing during operation
Solution Approach 1:
The patent applies parameter changes by deliberately varying the clearance parameter of teeth based on their axial position. Teeth at different locations have different clearance values, with those closer to the tight fit engagement having larger clearance. This parameter variation compensates for thermal expansion and deformation effects, preventing rubbing while maintaining operational reliability.
3Device complexity
If all teeth have the same clearance, then the seal structure is simpler, but clearance variations due to tight fit and temperature gradients cause performance degradation
Solution Approach 1:
The patent implements local quality by assigning different clearance values to teeth based on their location. The clearance varies axially along the seal, with teeth nearer to the tight fit engagement having greater clearance. This localized differentiation maintains consistent sealing performance across varying operating conditions while avoiding unnecessary complexity in the overall seal structure.
Data Source
AI summary
A labyrinth seal, has: rotating and static components rotatable relative to one another relative to a central axis, the rotating component securable to a shaft via a tight fit engagement at an engagement location on the rotating component, the static component securable to a housing; teeth protruding from one of the rotating and static components towards a seal land defined by the other one of the rotating and static components; and clearances between the teeth and the seal land, a first clearance of the clearances greater than a second clearance of the clearances, the first clearance located closer to the engagement location of the rotating component than the second clearance.