Labyrinth Seal Mobile Component Thermal Expansion Clearance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional labyrinth seals in rotating machines face challenges in maintaining low clearance during hot operation due to differential thermal expansions, leading to increased gas leaks and potential machine damage, as reducing clearance is constrained by transient and steady-state variations.
Innovation Solution
A labyrinth seal design featuring a mobile component with a conical interface and a spring, where the mobile component has a lower thermal expansion coefficient than the static parts, allowing for reduced clearance through sliding contact and the use of a liquid sealing surface that replaces abradable material, maintaining contact and preventing disjunction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the clearance is reduced to improve sealing performance, then gas leaks are reduced and pressure loss is minimized, but differential thermal expansion during transient states causes negative clearance leading to seal destruction
Solution Approach 1:
The sealing component is made mobile rather than fixed, allowing it to dynamically adjust its position in response to thermal expansion variations. The component can move axially to maintain positive clearance during transient states while achieving minimal clearance during steady-state cruising, thus preventing seal destruction while minimizing gas leaks and pressure loss
Solution Approach 2:
The invention changes the clearance parameter dynamically rather than maintaining a fixed value. By allowing the sealing component to move, the clearance varies between a minimum value during steady-state cruising (reducing leaks) and a larger value during transient states (preventing negative clearance and seal destruction)
2Loss of energy
If the clearance is reduced at steady-state cruising rate, then gas leaks are minimized, but a minimum clearance must be maintained for seal mounting which limits how small the clearance can be
Solution Approach 1:
The mobile sealing component allows the clearance to be dynamically adjusted: a larger clearance is provided during mounting and transient operations to facilitate assembly and prevent negative clearance, while the clearance automatically reduces to a minimal value during steady-state cruising to minimize gas leaks
3Reliability
If abradable material is used to prevent seal destruction during negative clearance, then seal integrity is maintained, but wear of abradable material increases gas leaks when clearance returns to normal
Solution Approach 1:
Instead of using abradable material that wears down, the invention uses a mobile component that actively moves to maintain positive clearance. This dynamic adjustment prevents the need for sacrificial abradable material, thereby avoiding the trade-off between seal protection and increased gas leaks from material wear
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 gas leaks by maintaining a low clearance at steady-state cruising rates, preventing seal destruction and machine damage, while the liquid sealing surface avoids wear and maintains a smooth sealing surface, significantly reducing air leakage.
Implementation Method 1
a spring maintaining said mobile component against the conical face of the collar by a thrust along the axis of rotation
Implementation Method 2
the mobile component and the collar have different thermal expansion coefficients
Data Source
AI summary
One of the components (15), opposite a labyrinth seal (12), is arranged sliding on a conical interface (18) of its support (7, 19) and constructed from a material with different thermal expansions, so as to reduce the clearance with the component face to face (13, 14), at steady state, at high temperature. The sealing surface (25) may be assured by a circulation of oil.