Turbine Mobile Sealing Ring Anti-Rotation Flange Design
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Solution Overview
Problem
Turbine turbomachine assemblies with movable sealing rings face issues of flange opening due to thermal gradients and centrifugal forces, leading to reduced service life, mechanical stress, and potential leaks, as well as challenges in maintaining effective sealing and cooling.
Innovation Solution
An anti-rotation system is implemented using a rotor disc fastening flange with circumferentially distributed teeth and a movable ring fastening flange with lugs, which engages to prevent rotation of the movable ring relative to the rotor discs, reducing thermal and centrifugal stresses, and a ventilation system is integrated to enhance cooling and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the movable ring is fastened to the bolted connection, then the sealing function is ensured, but the thermal gradient causes high stresses at the fastening flanges leading to flange opening and reduced service life
Solution Approach 1:
The movable ring is extracted from the bolted connection assembly, being fastened independently to the downstream shroud. This separation removes the movable ring from the thermal gradient zone of the bolted connection, eliminating the thermal stresses that caused flange opening while preserving the sealing function through the independent wiper mechanism.
Solution Approach 2:
The downstream shroud acts as an intermediary element between the movable ring and the rotor disc assembly. By fastening the movable ring to the shroud rather than directly to the bolted connection, the shroud mediates the thermal and mechanical loads, protecting the bolted connection from thermal gradient-induced stresses.
2Reliability
If the movable ring is subjected to high temperatures, then the sealing contact with fixed vane is maintained, but the thermal gradient between outer and inner annular portions causes deformation and creeping
Solution Approach 1:
The movable ring is extracted from the bolted connection structure and fastened independently to the downstream shroud. This repositioning removes it from the high-temperature zone near the fixed vane contact, reducing the thermal gradient across the ring and preventing deformation and creeping while maintaining sealing contact through proper positioning.
3Strength
If the bolted connection is subjected to centrifugal forces, then the rotor discs remain assembled, but the screw crown extends radially causing flange deformation and potential leaks
Solution Approach 1:
The assembly is segmented into separate functional zones: the bolted connection maintains rotor disc assembly integrity, while the movable ring fastened to the downstream shroud handles sealing independently. This segmentation prevents the transmission of centrifugal-induced deformations from the bolted connection to the sealing interface.
4Adaptability or versatility
If the movable ring is allowed to rotate relative to rotor discs, then the sealing wipers can adapt to vane position changes, but rotation generates wear and reduces service life
Solution Approach 1:
The movable ring is designed to self-adjust its radial position through the interaction between its wipers and the fixed vanes, maintaining sealing contact without requiring rotation. The independent fastening to the downstream shroud provides stable radial positioning, allowing the wipers to adapt to vane position changes through elastic deformation rather than rotational movement, thereby reducing 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 anti-rotation system significantly increases the service life of turbomachine turbines by minimizing flange opening, maintaining mechanical strength, ensuring effective sealing, and simplifying maintenance, while the ventilation system reduces thermal gradients and enhances cooling efficiency.
Implementation Method 1
a rotor disc fastening flange having a plurality of teeth distributed circumferentially around the longitudinal axis of the turbomachine, and a movable ring fastening flange having a plurality of lugs distributed circumferentially around the longitudinal axis of the turbomachine, the engagement of the rotor disc fastening flange with the movable ring fastening flange ensuring, via the teeth and the lugs, the anti-rotation of the movable ring relative to the rotor discs
Implementation Method 2
a ventilation system is integrated to enhance cooling and sealing
Implementation Method 3
the outer annular portion of the movable ring 28 is subjected to very high temperatures due to the circulation of hot air within the flow path 14. This results in a strong thermal gradient between the outer annular portion of the ring 28 and its inner annular portion
Implementation Method 4
The radial wipers 32 of the movable ring 28 cooperate with the inner annular surface of the fixed vane 12 opposite said ring 28, and thus ensure the sealing between a successive upstream cavity and downstream cavity of the flow path 14 of the turbine
Implementation Method 5
the bolted connection 26 is subjected to centrifugal forces related to the rotation of the rotor discs 20a, 20b. These forces act on the screw crown of the bolted connection 26 which tends to extend radially so as to increase its radius
Data Source
AI summary
The invention relates to an assembly (1) for a turbine of a turbomachine, comprising: a first rotor disk (20a), a second rotor disk (20b), a part forming a mobile ring (28), comprising a system for preventing rotation of the mobile ring (28) relative to the rotor disks (20a, 20b), said system comprising: a rotor disk securing flange (222) having a plurality of teeth (224) that are distributed circumferentially about the turbomachine longitudinal axis (X-X), and a mobile ring securing flange (282) having a plurality of lugs (284) that are distributed circumferentially about the turbomachine longitudinal axis (X-X), the engagement of the rotor disk securing flange (222) with the mobile ring securing flange (282) ensuring, by means of the teeth (224) and the lugs (284), that the mobile ring (28) does not rotate relative to the rotor disks (20a, 20b).