Unducted Fan Rotor With Sectorized Crown And Annular Groove
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Solution Overview
Problem
Current propeller designs for turbomachines with unducted propellers face rapid deterioration due to high centrifugal forces transmitted through fragile screw threads, limiting the propeller's lifespan.
Innovation Solution
The propeller design features a sectorized crown that interlocks with an annular groove on the blade support plate, using large annular support surfaces to transmit forces instead of threads, with each crown sector engaging in a radial translation to secure the crown within the groove, ensuring the forces are absorbed by the bearing and distributed effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If screw threads are used to transmit forces between blade support plate and crown, then the structure is simple, but the threads are fragile and deteriorate rapidly under high centrifugal forces
Solution Approach 1:
The crown is divided into multiple crown sectors that are fitted onto the plate body. Each crown sector is engaged in the housing from the inside and moved in radial translation so that its internal part fits into an annular groove of the plate body, distributing the force transmission across multiple segmented components rather than relying on fragile threads.
Solution Approach 2:
The screw threads are completely removed from the force transmission path. The connection between plate and crown is achieved through an annular groove and crown sectors with large annular support surfaces, extracting the problematic threaded connection while maintaining structural integrity.
2Reliability
If large annular support surfaces are used to transmit forces, then the propeller lifespan increases, but the device complexity increases due to sectorized crown and groove engagement
Solution Approach 1:
The crown sectors are merged with the housing structure, where each sector is engaged in the housing from the inside and integrates with the internal rim bearing structure. This merging reduces the number of separate components while maintaining the force distribution benefits.
Solution Approach 2:
The crown sectors automatically engage and lock into the annular groove of the plate body through radial translation. The design allows self-alignment and self-securing through the interlocking geometry of the groove and crown sector internal parts, reducing the need for additional fastening mechanisms.
3Strength
If crown sectors are engaged from the inside in radial translation, then the force transmission is improved, but the manufacturing precision requirements increase for groove and sector alignment
Solution Approach 1:
The design incorporates bearings between the crown sectors and the internal rim of the housing, as well as between the plate and housing. These bearings provide cushioning and accommodate minor misalignments, protecting the precise groove-sector interface from excessive stress and reducing the severity of precision requirements.
Solution Approach 2:
The annular groove acts as an intermediary feature that mediates the connection between the plate body and crown sectors. The groove provides a predetermined engagement path that guides the crown sectors into proper alignment, reducing the need for extremely tight tolerances in the final positioned alignment.
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
This design significantly increases the propeller's lifespan by distributing high centrifugal forces through robust annular surfaces and bearings, reducing the risk of premature failure.
Implementation Method 1
the centrifugal forces applied to the blade in operation are taken up by the part of the crown fitted in the groove of the plate and transmitted by the bearing to the rotor element
Data Source
Figure 1~2
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Figure 6~7
AI summary
The invention relates to a non-streamlined propeller having blades with a variable setting for a turbine engine, the blades of the propeller being rotatably mounted about the axes thereof in radial recesses (136) of a rotor element (124), and each blade being supported by a plate (144) held in a recess by a sectored ring (150), and including an inner portion (160) mounted, by interlocking, in a groove (162) of the plate, the ring sectors being inserted into the recess from the inside and locked by a nut (170) screwed onto the plate.