Unducted Propeller Spanwise Load Distribution
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Solution Overview
Problem
Open rotor gas turbine engines with contra-rotating rotor assemblies face challenges in simplifying design complexity while maintaining propulsive efficiency, as they require complex power transmission to opposing rotor assemblies.
Innovation Solution
An unducted thrust producing system with a single rotating propeller assembly and stationary vanes, where the rotating element has a load distribution that maintains a high ΔRCu value across its span, ensuring efficient thrust production and reduced complexity by using a drive mechanism to power the rotating element and vanes to manage swirl energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contra-rotating rotor assemblies are used to improve propulsive efficiency, then larger fan blades can act upon a larger volume of air, but the design complexity increases due to the need for complex power transmission to opposing rotor assemblies
Solution Approach 1:
The patent merges the function of two contra-rotating rotor assemblies into a single rotating propeller assembly with a specific spanwise load distribution. This combines the thrust-producing capability of multiple rotors while eliminating the complex power transmission system required to drive them in opposite directions, thereby reducing design complexity while maintaining propulsive efficiency
2Device complexity
If a single rotating propeller assembly is used to reduce design complexity, then power transmission is simplified, but achieving equal or better propulsive efficiency compared to contra-rotating designs becomes challenging
Solution Approach 1:
The patent applies local quality by implementing a specific spanwise load distribution on the propeller blades where the load is concentrated in the inner 30% of the blade span. This non-uniform distribution optimizes the aerodynamic performance of each section of the blade, allowing a single rotating assembly to achieve propulsive efficiency comparable to or exceeding contra-rotating designs while maintaining simpler mechanics
3Loss of energy
If uniform ΔRCu distribution is maintained across the rotating element to minimize exit swirl, then kinetic energy loss is reduced, but the blade design becomes more constrained
Solution Approach 1:
The patent changes the key parameter of blade loading from a conventional uniform or tip-concentrated distribution to a specific spanwise distribution where 60% or more of the total load is carried within the inner 30% of the blade span. This parameter change enables uniform ΔRCu distribution and minimized exit swirl while providing clear design guidance for manufacturing
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 high propulsive efficiency and reduced complexity by maintaining a uniform ΔRCu distribution across the rotating element, minimizing exit swirl and kinetic energy loss, and offering noise reduction through the use of a partial duct to shield noise-generating interactions.
Implementation Method 1
The rotating element includes a plurality of blades each having a blade root proximal to the axis, a blade tip remote from the axis, and a blade span measured between the blade root and the blade tip. The rotating element has a load distribution such that at any location between the blade root and 30% span the value of ΔRCu in the air stream is greater than or equal to 60% of the peak ΔRCu in the air stream.
Implementation Method 2
An unducted thrust producing system with a single rotating propeller assembly and stationary vanes, where the rotating element has a load distribution that maintains a high ΔRCu value across its span, ensuring efficient thrust production and reduced complexity by using a drive mechanism to power the rotating element and vanes to manage swirl energy.
Data Source
AI summary
An unducted thrust producing system has a rotating element with an axis of rotation and a stationary element. The rotating element includes a plurality of blades, each having a blade root proximal to the axis, a blade tip remote from the axis, and a blade span measured between the blade root and the blade tip. The rotating element has a load distribution such that at any location between the blade root and 30% span the value of ΔRCu in the air stream is greater than or equal to 60% of the peak ΔRCu in the air stream.