Aircraft Hybrid Engine Geared Ring Fan Torque Control
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Solution Overview
Problem
Conventional hybrid propulsion systems for aircraft require oversized electric motors for maximum power conditions and necessitate a specific powerful generator, leading to inefficiencies and complexity in engine design.
Innovation Solution
A propulsion engine with multiple fan units, each encased in a geared ring, where a gas turbine engine drives one fan and an electric machine with a storage device drives another, allowing for torque transmission and reversible operation as a motor or generator, eliminating the need for a direct electric connection and specific generator, with a controller managing power distribution and charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional hybrid propulsion systems use a specific powerful generator on the jet engine to drive the electric motor, then the maximum power requirement is met, but the electric motor becomes oversized for cruise conditions and efficiency decreases
Solution Approach 1:
The propulsion system is divided into two independent fan units: a first fan directly driven by the gas turbine engine, and a second fan driven by an electric motor connected to an electric storage device. This segmentation allows each fan to be optimized for different operating conditions, with the first fan handling maximum power requirements and the second fan providing supplemental thrust, thereby avoiding the need for an oversized electric motor that would operate inefficiently during cruise.
Solution Approach 2:
The electric storage device serves multiple functions: it provides electrical energy to the electric motor during take-off and climb phases, and can be recharged during cruise phases when the first fan operates independently. This multi-functionality allows the system to meet maximum power requirements while maintaining efficiency during lower-power operations, as the electric motor is not continuously overloaded.
2Power
If the engine core is oversized for take-off requirements, then maximum power is achieved, but the engine is inefficient during cruise operations
Solution Approach 1:
The propulsion system separates the functions of maximum power generation and efficient cruise operation into two distinct fan units. The first fan, directly coupled to the gas turbine engine, provides efficient cruise operation, while the second fan, driven by the electric motor and storage device, supplements power during take-off and climb. This allows the gas turbine engine to be optimized for fuel efficiency during cruise rather than being oversized for maximum power.
Solution Approach 2:
The system dynamically changes operational parameters by switching between different propulsion configurations: during cruise, only the first fan operates at efficient parameters; during take-off and climb, the second fan is activated to provide additional thrust. This parameter change allows the engine core to operate at optimal efficiency points for each flight phase rather than maintaining oversized capacity throughout.
3Power
If a hybrid propulsion system uses electric motors to drive fans during take-off and climb, then power requirements are met, but the system requires complex generator and motor configurations
Solution Approach 1:
The system is segmented into two independent propulsion units, each with its own fan and drive mechanism. The first unit uses direct mechanical coupling between the gas turbine engine and fan, while the second unit uses an electric motor connected to an electric storage device. This segmentation simplifies the overall system architecture by avoiding the need for a single complex generator-motor system, making each subsystem more manageable and easier to control independently.
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
Enables efficient power management across various flight conditions, reducing the need for oversized components, improving fuel efficiency, and allowing for silent operation by optimizing the use of both thermal and electric power sources.
Implementation Method 1
a geared ring connected to a second shaft operatively coupled to an electric machine... The geared rings are configured to transmit torque between the fans
Implementation Method 2
The electric machine of the second propulsion unit is arranged for actuating, in combination with the electric storage device, whether as an electric motor extracting energy from the electric storage device to drive the second shaft or as an electric generator extracting the mechanical energy of the second shaft
Data Source
AI summary
A propulsion engine comprising at least a first propulsion unit including a first fan encased by a geared ring and a gas turbine engine driving a first shaft connected to the first fan, at least a second propulsion unit including a second fan encased by a geared ring connected to a second shaft operatively coupled to an electric machine and at least an electric storage device connected to the electric machine. The geared rings are configured to transmit torque between the fans so that they can rotate in conjunction (directly or through an intermediate gear) when they are driven by at least one of said first and second shafts. The propulsion engine is arranged for controlling the torque to be supplied to the assembly of the first and second fans by the gas turbine engine and/or by the electric machine acting as a motor or as a generator.