Dual Open-Rotor Propeller Layout for Flexible Power Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbomachines of open rotor type face limitations in power efficiency and mechanical power extraction, particularly during varying thrust requirements, leading to degraded performance and increased compressor dimensions for electrical aircraft applications.
Innovation Solution
A turbomachine architecture with two open-rotor propellers, where the first propeller is driven by a low-pressure shaft and the second propeller is driven by an electric motor, with adjustable shimming and operating modes to optimize power distribution and efficiency, including power storage and reversal capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a counter-rotating open rotor (CROR) turbomachine with twin counter-rotating propellers is used, then propulsive efficiency is improved and outer dimensions are reduced, but device complexity increases due to dual pitch setting systems and rotating casings
Solution Approach 1:
The invention divides the propulsive system into two independent propellers (first and second propellers) with separate drive systems. The first propeller is driven by the low-pressure shaft while the second propeller is driven by an electric motor, allowing independent control and simplification of each subsystem compared to a fully coupled CROR system
Solution Approach 2:
The invention replaces the mechanical coupling system of traditional CROR (with rotating casings and dual pitch setting systems) with an electrically-driven second propeller. This substitution eliminates the need for complex mechanical transmission systems while maintaining the benefits of counter-rotating propellers
2Device complexity
If the gas generator and propulsive parts operate with one-on-one correspondence, then system simplicity is maintained, but overall performance degrades during thrust reduction phases due to low power levels
Solution Approach 1:
The invention introduces dynamic adaptability by enabling the second propeller to be driven by an electric motor independently of the gas generator's power output. This allows the system to optimize performance across varying thrust requirements by adjusting the electric motor's power contribution, preventing all components from operating at inefficient low power levels during cruise and idle phases
Solution Approach 2:
The second propeller serves multiple functions: it can be driven by the electric motor for primary propulsion, by the low-pressure shaft for mechanical power extraction, or in combination of both. This multi-functionality allows the system to maintain high efficiency across different operating conditions while providing flexibility in power distribution
3Power
If mechanical power is extracted from the shafts of the turbomachine, then power for electrical aircraft systems is provided, but compressor operability is impacted and compressor dimensions must be increased
Solution Approach 1:
The invention introduces an electric motor as an intermediary power source for the second propeller. This intermediary allows mechanical power to be extracted from the low-pressure shaft for electrical generation without directly impacting the compressor's operational requirements, as the electric motor can compensate for any power extraction effects
Solution Approach 2:
The invention segments the power extraction function from the compressor system by using the low-pressure shaft (downstream of the compressors) as the source for driving the electric motor. This segmentation isolates the power extraction process from the compressors, allowing them to be optimized for their primary function without being overdimensioned to accommodate power extraction 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 configuration enhances the overall performance of the turbomachine by optimizing power usage and reducing compressor load, improving efficiency and reducing noise levels while enabling effective mechanical power extraction for electrical aircraft systems.
Implementation Method 1
a low-pressure turbine configured to rotationally drive a low-pressure shaft
Implementation Method 2
the second propeller being rotationally driven by an electric motor
Implementation Method 3
a first propeller; and a second propeller downstream of the first propeller
Data Source
AI summary
A turbomachine of an aircraft comprising an outer casing delimiting with an inner hub, a flow path of a gas stream in which is disposed a low-pressure turbine configured to rotationally drive a low-pressure shaft; said turbomachine comprising, in the direction of flow of the gas stream, a first propeller; and a second propeller downstream of the first propeller, the first propeller being rotationally driven by said low-pressure shaft and the second propeller being rotationally driven by an electric motor, the second propeller being further disposed at a distance between 1.5 and 4 cord lengths from the first propeller defined between the respective axes of shimming of each of the first and second propellers.