Research On Key Technologies Of Electric Green Taxi System With Powered Wheel Drive For Large Civil Aircraft

Green aviation has become an urgent topic of concern in the field of international aviation.Since the taxi time of the civil aircraft has been rising significantly for many years and will still rise in the future,electric green taxi system with powered wheel drive for large civil aircraft is designed,as it uses auxiliary power unit to actuate the powered wheels in nose landing gear or main landing gears,which aims to allow the aircraft to begin pushback and taxi forward fully autonomously without using its main engines.The benefits of electric green taxi system include saving of fuel burn and repair costs,reduction of carbon emission and noise pollution,improvement of safety on apron and optimization of precision maneuvering etc.The overall architecture of electric green taxi system is established,in order to solve the problems of engine low efficiency,high fuel consumption and high pollution of the single-aisle civil aircraft C919 during the taxi process.The powered wheel drive and integrated control strategy of electric green taxi system are studied.The components and subsystems of electric green taxi system are initially designed and integrated.A new type of powered wheel drive system suitable for civil aircraft wheel is designed,as an electric traction motor with high power and high torque density is selected,and the parameters of the planetary gear assembly of the powered wheel are designed and optimized.In order to replace the actual vertical load of the power wheel of civil aircraft during the taxi process,two test schemes using moment of inertia and resistance loading are designed: The first scheme uses the mass block to simulate the mass of the small general aircraft;The second scheme uses free wheels with variable moment of inertia to simulate the mass of large civil aircraft.Powered wheel drives equipped with traction motors can provide taxi capability without the use of main engines or a tractor.The ground handling characteristic of aircraft with electric green taxi system is analyzed.The new mathematic model of aircraft ground maneuver is established,considering the six-degree-freedom aircraft body and the flexible main strut and the powered wheel.Quasi-steady method is applied to calculate tire lateral force and self-aligning torque,in order to determine the side slip.The simulation for the ground steering response of aircraft with electric green taxi system is done by employing co-simulation platform,and the dynamic responses of aircraft ground steering is simulated.Four different taxi conditions including simultaneous main wheel mode,only outside main wheel mode,only nose wheel mode,differential main wheel mode are compared.Three conclusions are obtained: Electric green taxi system can help the civil aircraft turn on the spot;Differential powered main wheel mode has the minimum turning radius while turning-circle with uniform velocity,and it has smaller difference between two vertical loads of main landing gears than powered nose wheel mode;In the case of the same steering angle,the extreme velocity of differential powered main wheel mode before the side slip is larger than powered nose wheel mode.Powered wheel drives equipped with traction motors can provide capability of main wheel pre-rotation before touchdown.The mathematic model of landing is established,considering the six-degree-freedom aircraft and the flexible main strut and the powered wheel.The dynamic responses of landing gear spin-up and spring back are simulated.Different landing conditions considering the different peripheral velocities of powered main wheels are compared.Three conclusions are obtained: Electric green taxi system pre-rotates powered main wheels to decrease spin-up and spring back drag load;The pre-rotation of wheels decreases probability of strut binding especially at the moment of first touchdown;The multi-body dynamic model considering flexible deformation of struts causes higher frequency vibration of force curves than the rigid dynamic model.