Variable-Pitch Propeller Vane Bulb-Cup Attachment for Wear Control
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Solution Overview
Problem
Existing propeller vanes with variable pitch face issues such as premature wear and increased mass due to conventional attachment methods, which are not suitable for large span and wide chord blades, leading to vibratory excitation and frictional damage.
Innovation Solution
A propeller vane assembly with a bulb-shaped root featuring a recess in the free end and a protuberance on the cup, allowing for a more secure and lightweight attachment by reversing the conventional configuration, reducing the overall footprint and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional broached attachment method is used for the vane root, then the vane can be securely mounted, but the root moves rigidly in its slot causing frictional damage to the blade and wedge in just a few cycles
Solution Approach 1:
Instead of the vane root moving within a slot (conventional approach), the invention inverts the mechanism by having the cup rotate within a fixed recess in the vane root. This reversal eliminates the rigid movement and frictional damage between the root and wedge, while maintaining secure mounting through the bulb-shaped root geometry engaged in the cup.
2Reliability
If a bulb fastener is used to reduce ball-jointing, then premature wear is reduced, but the protuberance in the free end of the root represents significant mass
Solution Approach 1:
The invention inverts the conventional bulb fastener configuration by moving the protuberance from the free end of the root (where it adds mass) to the bottom wall of the cup (where it serves as a counterweight and balance element). This reversal maintains the anti-ball-jointing function while minimizing the mass penalty, as the protuberance is now positioned to counterbalance aerodynamic forces rather than adding to the vane's operational mass.
3Force
If the pitch of the vanes is increased to generate thrust, then the resulting force displaces towards the propeller plane increasing drag and decreasing thrust
Solution Approach 1:
The invention enables dynamic pitch adjustment of the vane blades through the cup mechanism that allows rotational movement. This dynamic capability allows the propeller to optimize its pitch angle according to operating conditions, maximizing thrust generation while minimizing drag by adapting the blade angle to the required power output, rather than being fixed in a single configuration.
Data Source
AI summary
An assembly including a propeller blade and a system for angularly setting the pitch of the blade for an aircraft turbomachine, the blade having a root extending from an upper end connected to an airfoil of the blade to a free lower end, the root having a bulging segment, which bulging segment is referred to as the “bulb”, the system for angularly setting the pitch of the blade including a cup which is radially defined by an annular wall and which includes a lower bottom closed by a bottom wall and an upper opening through which the bulb is intended to be axially inserted into the cup, the bottom wall including a protrusion which engages with a cavity having a complementary shape in the free end of the root.