Aircraft Electric Propulsion Engine Flexible Driveshaft
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Solution Overview
Problem
Conventional aircraft propulsion systems face inefficiencies due to drag, which is not adequately reduced by existing boundary layer ingestion systems that reintroduce slow-moving air into turbofan jet engines, leading to nonuniform velocity profiles and efficiency losses.
Innovation Solution
The proposed propulsion system incorporates an electric motor, power gearbox, and fan with a flexible driveshaft and torsional dampers to accommodate vibrations and misalignments, and a boundary layer ingestion (BLI) fan mounted at the aft end of the aircraft to ingest boundary layer air, reducing drag while maintaining engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If boundary layer ingestion systems route slow moving air into turbofan jet engines, then drag on the aircraft is reduced, but the velocity profile becomes nonuniform causing efficiency loss
Solution Approach 1:
The inlet is divided into multiple segments with individual controllable elements (such as adjustable guide vanes or flow control mechanisms) that can independently regulate airflow from different portions of the boundary layer. This segmentation allows the system to ingest beneficial slow-moving air for drag reduction while selectively managing nonuniform flow regions to maintain engine efficiency.
Solution Approach 2:
The inlet configuration incorporates dynamically adjustable components that can change their position or orientation in response to varying flight conditions and boundary layer characteristics. This dynamic adaptation enables the system to optimize the balance between drag reduction and flow uniformity delivery to the engine across different operating regimes.
2Device complexity
If rigid connection is used between electric motor and power gearbox, then structural simplicity is maintained, but vibrations and misalignments cause reliability issues
Solution Approach 1:
A flexible coupling element connects the electric motor to the power gearbox, allowing this flexible connection to accommodate vibrations and misalignments between the two components. The flexible coupling may incorporate elastomeric materials, flexible membranes, or compliant mechanical structures that absorb dynamic disturbances while transmitting torque, thereby maintaining reliability without significantly increasing structural complexity.
Solution Approach 2:
An intermediary component (such as a flexible coupling or damping element) is introduced between the electric motor and power gearbox to mediate the transmission of power while isolating vibrations and misalignments. This intermediary acts as a buffer that protects the connected components from harmful dynamic effects while maintaining the overall simplicity of the drivetrain structure.
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 effectively reduces aircraft drag by optimizing airflow and accommodating operational vibrations, thereby enhancing propulsion efficiency without compromising engine performance.
Implementation Method 1
The driveshaft includes a flexible element for accommodating a misalignment between the electric motor and the power gearbox
Implementation Method 2
The propulsion system incorporates an electric motor, power gearbox, and fan with a flexible driveshaft and torsional dampers to accommodate vibrations and misalignments
Implementation Method 3
a boundary layer ingestion (BLI) fan mounted at the aft end of the aircraft to ingest boundary layer air, reducing drag
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A propulsion system 100 for an aircraft 10 includes an electric propulsion engine configured to be mounted to the aircraft 10 at an aft end of the aircraft 10. The electric propulsion engine includes a fan 304 rotatable about a central axis 302 of the electric propulsion engine. The fan 304 includes a fan shaft 330 mechanically coupled to a power gearbox 336. The electric propulsion engine also includes an electric motor 334 having a driveshaft, with the electric motor 334 coupled to the power gearbox 336 through the drive shaft 332. The electric motor 334 rotates the fan 304 through the power gearbox 336. The driveshaft includes a flexible element for accommodating a misalignment of the electric motor 334 and the power gearbox 336.