Slotted Labyrinth Seal Radial Clearance Variation
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Solution Overview
Problem
Current sealing systems in gas turbine engines, such as labyrinth and carbon seals, face challenges with radial leakage, high manufacturing costs, and reduced efficiency at high radii, leading to increased bearing load, heat generation, and reduced component lifespan due to fluctuations in pressure and temperature.
Innovation Solution
A slotted labyrinth seal with varying radial clearance and a unique fin configuration that adjusts based on shaft speed, allowing for effective sealing while minimizing rotor load and maintaining fluid flow, even with axial movement of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If labyrinth seals use a stair-step configuration to discretize radial cavities into quasi axial cavities, then radial leakage between concentric streams of fluid is reduced, but extremely accurate manufacturing and assembly techniques are required which are expensive and time consuming
Solution Approach 1:
The patent changes the geometric parameters of the seal fins, specifically varying the radial clearance between fins at different radii. The inner fins have smaller radial clearances while outer fins have larger radial clearances, optimizing sealing effectiveness across different regions without requiring uniform high-precision manufacturing throughout the entire seal structure.
Solution Approach 2:
The patent applies different radial clearance values to fins at different radial positions. Inner fins have tighter clearances for better sealing where pressure differentials are higher, while outer fins have larger clearances, creating a non-uniform seal structure that addresses local sealing needs rather than applying a uniform design throughout.
2Reliability
If carbon seals are used for low radius shaft or sump air-oil seal applications, then sealing is achieved, but cooling is required usually with oil and they become less effective at higher radii
Solution Approach 1:
The patent divides the seal into multiple discrete fins positioned at different radii, with each fin segment handling sealing at its specific radial location. This segmented approach allows optimization of each fin's characteristics for its local conditions, enabling effective sealing across a wide radial range from inner to outer fins.
Solution Approach 2:
The patent transitions from a single-plane sealing approach to a multi-radial-dimension sealing structure. By positioning fins at multiple radii and varying their clearances, the seal operates effectively in three-dimensional space, accommodating both low and high radius sealing requirements simultaneously.
3Reliability
If fins are positioned at multiple radii in a labyrinth seal, then sealing is improved, but load is applied to both rotating members of the seal due to pressure in the cavity between the fins
Solution Approach 1:
The patent varies the radial clearance parameter of fins at different radii to optimize the pressure distribution in the cavities between fins. By carefully selecting clearance values, the pressure forces acting on the fins and consequently on the bearings are controlled, balancing sealing effectiveness with load management.
4Adaptability or versatility
If the distance between abutting surfaces of the labyrinth seal changes due to mechanical and thermal movements, then relative movement of sealed components occurs, but the air flow through the seal can be restricted to an unacceptable level
Solution Approach 1:
The patent creates a dynamic seal system where the varying radial clearances of fins at different radii provide different compliance characteristics. When thermal or mechanical movements change the distance between abutting surfaces, the multi-clearance fin structure allows the seal to adapt and maintain acceptable air flow, preventing complete flow restriction that would occur with a single uniform clearance design.
Data Source
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AI summary
A seal for use in a machine, such as a machine with rotating members, includes a labyrinth seal with multiple fins. The seal is slotted and is designed to limit fluid flow to the desired amount from the high pressure side of the seal to the low pressure side of the seal inside partially or exclusively radially extending cavities between two rotating members. The rotating members may operate at different speeds with a common axis of rotation. The seal remains effective when the rotating members move axially in relation to one another despite the fins having a component parallel to the axis of rotation.