Expandable Piston Seal Structure for Symmetric Turbine Sealing
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Solution Overview
Problem
Existing gas turbine engine seals face challenges with asymmetric deflection under centrifugal forces, leading to locationally varied leaks, thermal loads, vibrations, and seal loads, which affect sealing performance and durability.
Innovation Solution
A diametrically expandable and collapsible seal with a tortuous seal wall and interconnected spring ligaments, made of metallic material, that can elastically expand for installation clearance and collapse into an annular channel, featuring axial through-channels and a flexible sealant to ensure symmetric sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional rigid seal is used, then the seal structure is simple and easy to manufacture, but the seal experiences asymmetric deflection under centrifugal forces leading to locationally varied leaks and reduced sealing performance
Solution Approach 1:
The seal transitions from a rigid static structure to a dynamic structure with spring ligaments that can deflect and adapt to centrifugal forces. The interconnected spring ligaments allow the seal to dynamically respond to operational conditions, maintaining symmetric contact with the seal surface while accommodating rotational forces that would cause asymmetric deflection in rigid seals.
Solution Approach 2:
The seal incorporates flexible spring ligaments that form a tortuous seal wall structure. These flexible elements allow the seal to deform elastically under centrifugal loading while maintaining its sealing function, preventing the asymmetric deflection that occurs with rigid seals and thereby eliminating locationally varied leaks.
2Stability of the object's composition
If the seal is made rigid to maintain structural stability, then manufacturing is easier, but thermal loads and vibrations increase due to asymmetric deflection
Solution Approach 1:
The spring ligament structure provides flexibility that allows the seal to absorb thermal expansion and vibration-induced movements without developing asymmetric deflections. This flexibility reduces thermal loads and vibrations by allowing the seal to adapt to temperature changes and dynamic conditions while maintaining structural integrity.
Solution Approach 2:
The seal combines metallic spring ligaments with flexible sealant materials to create a composite structure that provides both structural stability and flexibility. This composite approach allows the rigid metallic framework to provide overall structural support while the flexible sealant fills gaps and accommodates thermal expansion, reducing thermal loads and vibrations.
3Ease of operation
If the seal is made expandable for installation clearance, then ease of installation improves, but the seal structure becomes more complex
Solution Approach 1:
The seal incorporates dynamic expansion and collapse capabilities through its spring ligament structure. During installation, the seal can be expanded diametrically to clear the shaft, then collapses into the annular seal channel when installed, providing ease of installation without requiring complex assembly mechanisms. The same spring ligaments that provide operational flexibility also enable this installation advantage.
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 seal provides enhanced symmetric leakage, thermal loads, vibration, and seal loads, improving sealing performance and durability by preventing asymmetric deflection and maintaining consistent contact with the seal surface.
Implementation Method 1
the seal is elastically diametrically expandable for installation clearance around the shaft and, once on the shaft, elastically diametrically collapsible into the annular seal channel
Data Source
AI summary
A gas turbine engine includes a rotor that has a seal surface and a shaft that is rotatable about an engine central axis. The shaft has an annular seal channel that opens to the seal surface. There is a seal for sealing against the seal surface. The seal has channels formed therein that define a tortuous seal wall with interconnected spring ligaments such that the seal is elastically diametrically expandable for installation clearance around the shaft and, once on the shaft, elastically diametrically collapsible into the annular seal channel.