Unducted Single Rotor Engine with Variable Pitch Vanes
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Solution Overview
Problem
Conventional turbofan engines are limited by the size of their bypass fan, which restricts propulsive efficiency due to the increased size and weight of the nacelle with larger fans, while open rotor designs with contra-rotating rotor assemblies face challenges in power transmission to opposing direction rotor blades.
Innovation Solution
A propulsion system featuring a single unducted rotor engine with a vane assembly positioned aft of the rotor assembly, allowing for adjustable blade and vane pitch angles to modify thrust vector and efficiency, and incorporating a controller to execute operations for reverse thrust and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bypass fan size is increased in a conventional turbofan engine, then propulsive efficiency is improved, but the nacelle size and weight increase
Solution Approach 1:
The invention extracts the bypass fan from the enclosed nacelle structure, positioning it externally as an open rotor. This allows the fan to operate independently without being constrained by nacelle size limitations, enabling larger rotor diameters that improve propulsive efficiency while avoiding the weight penalty of an oversized nacelle.
Solution Approach 2:
The invention transitions from a two-dimensional constraint (fan size limited by nacelle cross-section) to a three-dimensional solution (open rotor extending beyond the original nacelle envelope). This dimensional change allows the rotor blades to sweep through a larger volume of air, increasing mass flow and propulsive efficiency without proportionally increasing nacelle weight.
2Productivity
If contra-rotating rotor assemblies are used in an open rotor engine, then propulsive efficiency is improved, but power transmission complexity increases
Solution Approach 1:
The invention merges the functions of two contra-rotating rotor assemblies into a single rotor assembly with variable pitch blades. This consolidation eliminates the need for complex dual-power transmission systems while maintaining the aerodynamic benefits of open rotor operation, thereby reducing mechanical complexity while preserving propulsive efficiency.
Solution Approach 2:
The invention introduces dynamic blade pitch control to a single rotor assembly, allowing the blades to adjust their angle of attack in real-time. This dynamic capability replaces the static contra-rotating configuration, enabling the same rotor to optimize its aerodynamic performance across different flight conditions without requiring a second rotor assembly.
3Productivity
If larger rotor blades are used in an open rotor design, then propulsive efficiency is improved, but structural weight increases
Solution Approach 1:
The invention employs composite materials in the construction of larger rotor blades, enabling the creation of lightweight yet structurally sound components. These composite structures provide the necessary strength and stiffness for larger blade spans while significantly reducing the weight compared to traditional metallic constructions, thereby maintaining propulsive efficiency gains without proportional weight increases.
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
The system achieves increased propulsive efficiency and reduced noise by allowing larger rotor blades to operate effectively, while minimizing the complexity and weight associated with traditional turbofan designs.
Implementation Method 1
a rotor assembly configured to rotate about a longitudinal axis of the engine... One or more blades of the rotor assembly are configured to rotate along a blade pitch angle axis
Implementation Method 2
A vane assembly is positioned in aerodynamic relationship with the rotor assembly. The vane assembly includes one or more vanes, wherein each vane includes a vane pitch angle
Data Source
AI summary
A propulsion system is provided, the propulsion system including a rotor assembly configured to rotate relative to the engine centerline axis, and wherein one or more blades of the rotor assembly are configured to rotate along a blade pitch angle axis. A vane assembly is positioned in aerodynamic relationship with the rotor assembly. The vane assembly includes one or more vanes, wherein each vane includes a vane pitch angle. A controller is configured to execute operations, the operations including moving each blade to a reverse thrust position about its respective blade pitch axis, and adjusting each vane about its respective vane pitch axis when the plurality of blades is in the reverse thrust position to modify an amount of reverse thrust generated by the propulsion system.