Aircraft Propulsion Power Transfer for Contrail Mitigation
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Solution Overview
Problem
Conventional aircraft propulsion systems result in contrails that contribute significantly to climate warming, with varying impacts due to interaction with wingtip vortices, and there is a need to manage contrail formation to reduce this impact.
Innovation Solution
An aircraft propulsion system with electrical power transfer between engines and adjustable fuel flow to maintain total thrust, optimizing contrail formation by altering fuel flow and electrical power distribution based on ambient and operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If fuel flow to engines is increased to maintain thrust during contrail formation, then contrail optical depth increases, but climate warming impact increases
Solution Approach 1:
The system dynamically adjusts fuel flow rates to individual engines based on real-time operating conditions and contrail formation risk assessment. The controller continuously monitors engine parameters, ambient conditions, and contrail likelihood, then modulates fuel flow dynamically to minimize contrail formation while maintaining required thrust levels, rather than using static fuel flow management
Solution Approach 2:
The system changes operational parameters (fuel flow rate, engine thrust distribution) in response to varying contrail formation conditions. When contrail formation is detected or predicted, the controller adjusts fuel flow parameters to reduce exhaust temperature and water vapor content, thereby reducing contrail optical depth and climate impact while compensating with electrical power
2Object-affected harmful factors
If electrical power is transferred from one engine to another to reduce contrail formation, then contrail optical depth decreases, but system complexity increases
Solution Approach 1:
The electrical machines serve multiple functions: they can operate as generators during normal operation to produce electrical power, and as motors during contrail reduction mode to receive power from other engines. This multi-functionality allows the system to use existing components for contrail management without adding dedicated hardware, thereby limiting the increase in system complexity
Solution Approach 2:
The system uses its own electrical machines and power generation capability to manage contrail formation. Rather than requiring external power sources or complex dedicated systems, the propulsion system itself generates and redistributes electrical power between engines to control exhaust characteristics and reduce contrail optical depth
3Object-affected harmful factors
If fuel flow is reduced to minimize contrail formation, then contrail persistence decreases, but total thrust may be insufficient
Solution Approach 1:
Electrical power acts as an intermediary to compensate for thrust loss when fuel flow is reduced. When the controller reduces fuel flow to minimize contrail formation, the electrical machines convert electrical energy to mechanical power to make up the thrust difference, ensuring total thrust requirements are met while still reducing contrail persistence
Solution Approach 2:
The system replaces purely mechanical thrust generation (fuel combustion) with a hybrid approach where electrical power substitutes for some mechanical thrust production. During contrail reduction mode, electrical machines provide a portion of the required thrust, allowing fuel flow to be reduced for contrail management while maintaining adequate total thrust through electrical assistance
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
Reduces the negative climate impact of contrails by managing their formation and characteristics, minimizing optical depth and spatial extent through controlled exhaust plume interaction with wingtip vortices.
Implementation Method 1
an electrical machine coupled to a spool of the first engine and to a spool of a second engine
Implementation Method 2
Contrail ice particles entrained in the vortices are subject to adiabatic heating due to descent of the vortex. As a result, ice mass can be lost from the surface of the entrained ice particles via sublimation
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
An aircraft propulsion system comprises first and second engines (100, 200) and first (134) and second electrical machines coupled to the first and second engines respectively. The first electrical machine is arranged to be driven by electrical power in order to at least partially drive the first engine. The second electrical machine is arranged to be driven by the second engine to generate electrical power. An electrical network (31) allows transmission of electrical power between the electrical machines. A controller (25) is arranged to selectively reduce fuel flow to the first engine and provide electrical power from the second electrical machine to the first electrical machine to drive the first electrical machine, based on expected properties of contrails formed in an exhaust plume of the first engine and/or the second engine. The system allows the formation of contrails by the engines to be managed in order to mitigate climatewarming effects of the contrails.