Force Optimization Of Pipeline Back-end For Air Refueling And Anti-disturbance Docking

With the development of modern military technology,the requirements of air operations on aircraft performance are getting higher and higher.In this case,engineers try to extend the flight time and distance of fighter aircraft by air refueling technology.Therefore,aerial refueling has been paid much attention by the researchers of the world’s military power,and various air refueling systems have been designed to improve the efficiency of refueling.Hose-drogue refueling occupies a place in the field of aerial refueling research because of its low cost and simple way.In the research of hose-drogue refueling system,docking process is a very important part.Docking control force and docking safety are two important indexes to evaluate its performance.Taking this as the starting point,this paper mainly studies the characteristics of the flexible air refueling hose-drogue and the docking control of the refueling machine and the oil receiver.In the aspect of the characteristics of the hose-drogue,the stress condition and the aerodynamic characteristics of the cone sleeve are analyzed.Firstly,the mathematical model between the airspeed of the tanker and the aerodynamic drag of the hose-drogue is established by using the method of catenary and dimensional analysis.Then,the optimal stability umbrella suitable for high speed and low speed refueling is determined by analyzing the aerodynamic characteristics of drogue.In the aspect of docking control,it is mainly accomplished through two aspects: the determination of cone trajectory and the tracking control of oil receiver.Firstly,based on fully studying the research on the movement characteristics of hose and drogue both at home and abroad,combined with the flight test data,the forces and influence factors of the hose-drogue in the docking stage are analyzed in detail.A new resistance prediction formula is proposed by combining catenary method and dimensional analysis.The calculation results are compared with the experimental data to verify the reliability of the method.Secondly,the influence of umbrella angle and number of umbrella braces on the drag coefficient of cone stabilizing umbrella is studied,and the shape of the optimal stable umbrella is determined.The six three dimensional models of different umbrella angle and number of braces are first established by SOLIDWORKS.Then,the relationship between the number of braces and the number of braces and the drag coefficient of the parachute is obtained by numerical simulation using Fluent.Finally,the optimal shape of the stable umbrella with high speed and low speed refueling is determined.Finally,the multi-body dynamics model of the hose-drogue is established,and the external characteristics of the hose-drogue and the trajectory of the drogue are obtained.The integrated docking system of the refueling machine and the oil receiver is completed through the guidance law and the control law.First,the multi-body model of hose-drogue is established by dynamic and kinematic analysis,and the influence of atmospheric turbulence is added.On the MATLAB/SIMULINK simulation platform,the trajectory of the hose-drogue in the external position is simulated.A reference trajectory is designed based on the relative position between the drogue and the oil receiver.Finally,the LQR-PID trajectory tracking controller is designed on the basis of LQR control.The docking process of the oil receiver and the refueling machine is simulated by the docking control system including the small disturbance linear dynamic model of the oil receiver,the motion trajectory of the drogue,the atmospheric turbulence,the guidance module and the control module.The simulation results show that the docking control system can control the receiver to dock with the tanker quickly and accurately,improve the docking efficiency of hose-drogue refueling,and has certain engineering application value.