Variable Pitch Fan Blade Feathering Mechanism
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Solution Overview
Problem
Existing ducted fan propulsion systems face challenges in reducing the hub ratio, which affects propulsive efficiency and fuel consumption, due to the traditional location and design of blade feathering devices.
Innovation Solution
A blade feathering device with a lever articulated around a fixed axis, featuring a flyweight that moves under centrifugal force to impose a feathered position on the blades, reducing the ring space and hub ratio by utilizing the available distance within the annular space between the shroud and the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the traditional blade feathering device is located radially between the blade pitch control device and the blade pivots, then the feathering function is achieved, but the outer shell diameter is increased, resulting in a higher hub ratio and reduced propulsive efficiency
Solution Approach 1:
The feathering device is repositioned from a radial arrangement to an axial arrangement within the annular space between the rotor and shroud. This dimensional change allows the feathering mechanism to occupy axial space rather than radial space, thereby reducing the outer shell diameter and hub ratio while maintaining the feathering function.
Solution Approach 2:
The invention uses a dynamic flyweight mechanism that moves under centrifugal force to engage the feathering function only when needed. The flyweight is positioned outside the annular space during normal operation and moves into the annular space under centrifugal force to impose the feathered position, allowing the device to be compact while maintaining full feathering capability.
2Productivity
If the hub ratio is reduced by extending the suction section, then the treated flow and propulsive efficiency are improved, but the blade feathering device requires more space, making reduction of the outer shell diameter difficult
Solution Approach 1:
The flyweight mechanism provides a dynamic solution where the feathering components are positioned outside the annular space during normal operation and only occupy the annular space when needed. This dynamic positioning allows the annular space to be minimized for high productivity while maintaining full feathering capability when required.
Solution Approach 2:
The flyweight is extracted from the annular space during normal operation and positioned outside it, allowing the annular space to be minimized. The flyweight is only introduced into the annular space when centrifugal force triggers the feathering function, thus separating the feathering capability from the normal operational space requirements.
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 enhances the bypass ratio and reduces fuel consumption by minimizing the hub ratio, improving the fan's performance and specific flow rate.
Implementation Method 1
a flyweight is fixed to the first end and the second end is coupled to said bearing, and where the flyweight, by centrifugal force, can move into a position in which said bearing imposes a feathered position to the blades
Data Source
AI summary
Fan module with variable-pitch blades for a propulsion system that includes:a rotor supporting the blades, and including an internal shaft and an external shroud, defining between them a space;a pitch control device (22) of the blades that includes a load transfer bearing;a feathering device of the blades;said feathering device includes at least one lever that is articulated around a fixed axis (A) in relation to the rotor, where said lever features a first end located outside said space and a second end located inside said space, and where a flyweight is fastened to the first end and the second end is coupled to said bearing.