Composite Propeller Cyclic Pitch for Lower Blade 1P Stress
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Solution Overview
Problem
Existing propulsion assemblies for aircraft with high bypass ratios face challenges in mechanical stress (1P stress) due to pressure differentials on propeller blades, leading to increased mass, consumption, and drag, while traditional solutions to improve efficiency, such as using metal blades, exacerbate these issues.
Innovation Solution
A propulsion assembly using composite material blades combined with a cyclic pitch device reduces mechanical loads by adjusting the pitch of each blade individually, allowing for a lighter and more efficient design, and includes a speed reduction device to optimize the rotational speed of the propeller and gas generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bypass ratio is increased to improve propulsive efficiency, then the mass flow rate of secondary air flow increases, but the diameter of the propulsion module increases, resulting in increased mass, consumption and drag
Solution Approach 1:
The patent applies a cyclic pitch device that dynamically adjusts the pitch angle of propeller blades during rotation. This dynamic adjustment allows the propulsion assembly to maintain optimal performance at higher bypass ratios without requiring excessive increases in diameter, thereby managing the trade-off between propulsive efficiency and mass.
Solution Approach 2:
The patent changes the operational parameters of the propeller blades through cyclic pitch adjustment. By varying the pitch angle dynamically during rotation, the system optimizes the interaction between air flow and blades, enabling efficient operation at high bypass ratios without proportionally increasing mass or drag.
2Productivity
If the bypass ratio is increased to improve propulsive efficiency, then the diameter of the propulsion module increases, but this results in increased consumption and drag
Solution Approach 1:
The cyclic pitch device dynamically adjusts blade pitch angles during rotation, allowing the propulsion system to maintain optimal aerodynamic efficiency at higher bypass ratios. This dynamic control reduces energy loss and drag by ensuring blades operate at optimal angles throughout the rotation cycle, preventing the energy penalties associated with larger diameters.
Solution Approach 2:
By changing the pitch angle parameter dynamically during operation, the system optimizes the aerodynamic characteristics of the propeller. This parameter adjustment allows efficient energy transfer at high bypass ratios without the increased consumption and drag that would result from simply increasing diameter.
3Strength
If traditional metal blades are used to resist mechanical stress, then the strength is sufficient, but the mass increases and efficiency decreases
Solution Approach 1:
The patent employs composite material blades that combine materials with different properties to achieve both sufficient strength and reduced mass. These composite blades are designed to withstand the mechanical stresses of high bypass ratio operation while maintaining lower mass than traditional metal blades, thereby improving overall efficiency.
Solution Approach 2:
The cyclic pitch device compensates for the reduced strength-to-weight ratio of composite materials by dynamically adjusting operating parameters. The pitch adjustment ensures that composite blades experience reduced mechanical loads during operation, allowing them to function safely and efficiently without requiring the mass of metal blades.
4Strength
If a cyclic pitch device is added to reduce mechanical stress, then the mechanical loads on blades are reduced, but the device complexity increases
Solution Approach 1:
The cyclic pitch device is designed to automatically adjust blade pitch angles based on operational conditions without requiring complex external control systems. The self-regulating mechanism reduces mechanical stress on blades while minimizing the addition of complexity to the overall propulsion assembly.
Data Source
AI summary
A propulsion assembly for an aircraft extends along an axis and includes a propulsion module having a propeller provided with blades, an outlet guide vane, and a propeller shaft to rotate the propeller. The blades of the propeller are entirely or partially made of composite material. The propulsion assembly further includes a gas generator having a drive shaft; a speed-reduction device rotationally coupling the drive shaft and the propeller shaft to drive the propeller shaft at a rotational speed lower than the rotational speed of the drive shaft; and a cyclic pitch device for the blades of the propeller.