Adaptive Labyrinth Seal Clearance Using Elastic Pressure Chambers
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Solution Overview
Problem
Labyrinth seals in turbomachines face challenges in maintaining optimal clearance under varying operating conditions, leading to leakage and potential contact damage, with existing solutions either being expensive or prone to material damage.
Innovation Solution
A device with two sealing elements, where the second sealing element has projections defining a labyrinth seal and is connected to the first sealing element through an elastic element, allowing clearance adjustment via fluid dynamic forces and pressure chambers to adapt to different operating conditions, using elastic deformation and mechanical stops for precise gap control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the clearance between labyrinth seal teeth and rotor is decreased to reduce leakage, then sealing performance is improved, but the risk of contact and material damage increases
Solution Approach 1:
The labyrinth seal is designed with elastic elements that allow the seal teeth to dynamically adjust their position relative to the rotor. The clearance varies from static to dynamic, enabling small clearances during normal operation for low leakage while automatically increasing clearance during vibrations or contact events to prevent damage
Solution Approach 2:
Elastic elements are pre-installed in the labyrinth seal structure to provide cushioning before contact occurs. These elements absorb impact energy and protect the rigid seal teeth and rotor from damage during transient contact events, allowing the use of smaller clearances without increasing damage risk
2Reliability
If the clearance is increased to avoid contact during critical speeds, then reliability is improved, but leakage increases under full load operating conditions
Solution Approach 1:
The seal transitions from a static clearance design to a dynamic one where the elastic elements allow the seal teeth to move closer to the rotor under normal operating conditions (reducing leakage) while maintaining sufficient clearance during critical speed passages (preventing contact)
3Reliability
If stator labyrinth seals are made of softer material like aluminium to preserve the rotor, then reliability is improved, but the teeth suffer damage and clearances increase leading to performance loss
Solution Approach 1:
Elastic elements are built into the stator seal structure to absorb impact energy before it reaches the seal teeth. This cushioning mechanism protects the hard seal teeth from damage during contact events, eliminating the need to use softer, more damage-prone materials
4Reliability
If alternative materials like thermoplastics are used to absorb shock, then reliability is improved, but the cost and manufacturing complexity increase
Solution Approach 1:
The elastic elements can be manufactured from the same material as the stator seal body, eliminating the need for expensive thermoplastic materials. This homogeneous material approach maintains shock absorption capability while simplifying manufacturing and reducing costs
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 leakage and prevents contact damage by automatically adjusting clearance based on fluid dynamic forces and pressure, ensuring optimal performance across various operating conditions while being cost-effective and easy to manufacture.
Implementation Method 1
The outer part of the second sealing element is connected to the first sealing element through an elastic element to allow the distance between the first sealing element and the second sealing element to vary depending on the fluid dynamic forces acting on the turbomachine components
Implementation Method 2
The device may comprise one or more pressure chambers located between the first sealing element and the second sealing element and configured to be in fluid communication with the processing fluid of the turbomachine to derive from such fluid communication a force acting on the outer part of the second sealing element in the direction of gap closure
Data Source
AI summary
A device configured to seal a circumferential gap between a first turbomachine component and a second turbomachine component mutually rotatable about a longitudinal axis. The device is provided with a first sealing element connected to the first turbomachine component and with a second scaling element having an inner part provided with a plurality of projections extending towards the second machine component to define the teeth of a labyrinth seal between the high pressure region and the low pressure region of the turbo machine. The outer part of the second sealing element is connected to the first sealing element through an clastic element. One or more pressure chambers located between the first sealing element and the second sealing element are in fluid communication with the processing fluid of the turbomachine to derive a force acting on the outer part of the second scaling element in the direction of gap closure.