Counter-Rotating Turbofan Torque Cancellation
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Solution Overview
Problem
Conventional turbofan engines apply torque in the same direction, requiring additional structural support to counteract the reaction torque, which can lead to increased weight and reduced aerodynamic efficiency in aircraft design.
Innovation Solution
The configuration of two turbofan engines with fans rotating in opposite directions, utilizing a star gearset and planetary gearset transmissions to transmit rotation from turbines to fans, allowing the torque from one fan to counteract the torque of the other, thereby minimizing the net torque applied to the aircraft frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fans of turbofan engines rotate in the same direction, then the engine configuration is simple, but additional structural support is required to counteract reaction torque, increasing aircraft weight
Solution Approach 1:
The patent applies the inversion principle by making the second fan rotate in the opposite direction to the first fan. This reverses the typical configuration where both fans rotate in the same direction, thereby generating counteracting torques that eliminate the need for additional structural support to counteract net torque, reducing aircraft weight.
Solution Approach 2:
The patent implements the counterweight principle by configuring the second fan to rotate in the opposite direction, creating a counter-torque that balances the torque from the first fan. This counterbalancing effect eliminates the net torque that would otherwise require additional structural support, effectively using one component's output to offset another's harmful effect.
2Device complexity
If fans of turbofan engines rotate in the same direction, then the transmission system is simple, but aerodynamic efficiency is reduced due to increased drag from additional structural support
Solution Approach 1:
The patent applies inversion by configuring the second fan to rotate in the opposite direction to the first fan. This eliminates the need for additional structural support elements that would create aerodynamic drag, thereby improving aerodynamic efficiency while maintaining transmission system manageability through the use of epicyclic gearsets.
Solution Approach 2:
The patent uses the counterweight principle to balance torques from oppositely rotating fans, eliminating the need for additional structural support. This removal of unnecessary structural elements reduces aerodynamic drag and improves overall aerodynamic efficiency.
3Weight of moving object
If fans rotate in opposite directions, then structural support requirements are reduced, but the transmission system complexity increases
Solution Approach 1:
The patent introduces an intermediary mechanism - the epicyclic gearset - to mediate between the turbines and fans. This gearset efficiently transmits and reverses rotation direction while providing compact integration, managing the complexity of opposite-rotation configuration without proportionally increasing overall system complexity.
Solution Approach 2:
The patent merges multiple functions into the epicyclic gearset, which simultaneously transmits power, reverses rotation direction, and integrates compactly within the engine assembly. This consolidation manages transmission system complexity by combining several functions into a single integrated component.
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 reduces the need for additional structural support to counteract torque, resulting in a more aerodynamic and lightweight aircraft design with reduced drag and improved performance.
Implementation Method 1
The first transmission may include a star gearset, and the second transmission may include a planetary gearset. The star gearset may include a sun gear coupled to the first turbine for rotation therewith, a plurality of planet gears intermeshed with the sun gear and mounted to a carrier grounded to a case, and a ring gear intermeshed with the plurality of planet gears and coupled to the first fan for rotation therewith.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An aircraft including a frame, a first turbofan engine coupled to the frame, and a second turbofan engine coupled to the frame is disclosed. The first turbofan engine includes a first turbine, a first fan coupled to the first turbine to be driven by rotation of the first turbine, and a first transmission coupled between the first turbine and the first fan to transmit rotation from the first turbine to the first fan. The second turbofan engine includes a second turbine, a second fan coupled to the second turbine to be driven by rotation of the second turbine, and a second transmission coupled between the second turbine and the second fan to transmit rotation from the second turbine to the second fan.