Inter-blade Platform Locking Ring for Low Hub Ratio
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Solution Overview
Problem
Current inter-blade platforms in aeronautical turbomachines face challenges in achieving a low hub ratio while ensuring precise fixation to the fan disk, which affects aerodynamic flow and inlet cone centering, particularly due to issues with centrifugal forces and clearance requirements.
Innovation Solution
The design incorporates a locking ring system with a fastening mechanism that includes a pin, sleeve, snap ring, and nut to securely attach the inter-blade platform to the fan disk, allowing for precise axial and radial centering of the inlet cone, and uses a composite material with fibrous reinforcement for structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the platform is taken up upstream and downstream with a bulky upstream attachment to absorb centrifugal forces, then the structural integrity is improved, but the hub ratio increases adversely
Solution Approach 1:
The attachment system is divided into two separate locations: upstream attachment to the disk and downstream attachment to an extension projecting from the disk. This segmentation allows the upstream attachment to be minimized in size while the downstream extension handles the centrifugal force absorption, thereby reducing the hub ratio while maintaining structural integrity.
Solution Approach 2:
The solution extends the attachment system in the radial dimension by adding an extension projecting from the disk. This allows the attachment points to be distributed along the radial direction, enabling the upstream attachment to be compact (improving hub ratio) while the downstream extension provides the necessary leverage for force absorption.
2Length of moving object
If the height between the platform surface and fan disk increases to reduce hub ratio, then the hub ratio is improved, but the platform fixation precision deteriorates
Solution Approach 1:
A locking ring is introduced as an intermediary component between the platform and the disk. The locking ring engages with both the platform and the disk extension, providing a mechanical constraint that maintains precise fixation. This intermediary allows the platform to be positioned at an optimal height for low hub ratio while ensuring accurate and stable fixation through the locking mechanism.
3Ease of operation
If a pin mounting system is used to allow axial mounting of the platform, then the ease of operation is improved, but the clearance requirements increase which may open clearances at the extrados trailing edges
Solution Approach 1:
The locking ring acts as an intermediary that provides axial positioning and retention of the platform. It engages with the platform and the disk extension to maintain precise axial positioning without requiring excessive clearances. This eliminates the need for large clearances that would be required by a simple pin mounting system, while still allowing easy axial mounting and dismounting operations.
4Reliability
If the platform presses against fixing points under centrifugal forces to secure fixation, then the reliability is improved, but the flow path is degraded due to seal degradation and flow disturbances
Solution Approach 1:
The locking ring serves as a mediator that distributes the centrifugal forces across multiple engagement points rather than concentrating them at single fixing points. This distributed force distribution maintains reliable fixation while minimizing localized pressure that could degrade seals and disturb the flow path, thereby preventing flow path degradation while maintaining fixation reliability.
Data Source
Figure 1~2
Figure 3~4a
Figure 4b
AI summary
The invention relates to a turbomachine fan having an axis of revolution and comprising a fan disk (10) having an upstream face and a radial face configured to receive a series of fan blades, an inter-blade platform comprising an upstream end (21), a base (27), at least one stiffener (25) extending radially from the base and configured to cooperate with the fan disk, an inlet cone, and a locking collar cooperating with the platform. The locking collar is attached and fixed on one side to the upstream end (21) of the platform and on the other side to the upstream face of the fan disk. The locking collar comprises a radial ring (31) and a lug (32), extending axially from the radial ring and configured to form a radial stop for the inlet cone.The blower further comprises a yoke (19) extending radially from the radial face of the disk and in which a third orifice (11) is formed, and an additional pin (13). The stiffener (25) comprises a tab in which a fourth through orifice (26) is formed, and the additional pin is configured to penetrate the third and fourth orifices so as to lock the platform relative to the blower disk.