Study On High-Speed Aerodynamic Stability Of Vehicle Under Overtaking Or Meeting Conditions Based On AMC Two-way Coupling Method

The surrounding flow field formed by the vehicles in the overtaking or meeting maneuver is complex,and changes drastically.The transient aerodynamic loads on the vehicle body interfering with each other changes rapidly,which has a great influence on the high-speed aerodynamic stability of the vehicles.Simultaneously,with the rapid development of the automobile industry,light weight has been further emphasized,which will also lead to more widespread and severe problems of high-speed instability of automobiles,and the importance of high-speed aerodynamic stability is highlighted.However,the previous research on aerodynamic stability of vehicles in overtaking or meeting maneuver mostly limited to the aerodynamics of the vehicles,but in fact,the change of the vehicle's trajectory and the attitude will affect the aerodynamic load.Therefore,in order to thoroughly study the aerodynamic stability of the vehicles under overtaking or meeting conditions,in this paper,the two-way coupling of aerodynamics and multibody dynamics coupling(AMC)model is studied,to analyzes the aerodynamic stability of a car and a coach under overtaking and meeting maneuver with different conditions.It has important engineering application value.The main research contents of this paper are as follows:1.Comparing different numerical simulation grid strategies,using the overset mesh based on Star-CCM+ to establish the vehicle aerodynamic model,and adopting the wind tunnel test of the car to provide experimental data for the verification of the aerodynamic model.The multi-body dynamics virtual prototype of the vehicle is established based on Adams/Car.Then the robustness of the model under aerodynamic interference is proved.2.The control logic of fluid analysis software Star-CCM+ and multi-body dynamics software Adams/Car is studied.A two-way coupling method between the two software is established.Secondly,by analyzing the wind spectrum of a natural wind measured data,a natural wind model with wind speed and direction changing with time is constructed.Through the comparison of one-way coupling and two-way coupling method under natural crosswind,it is proved that it is necessary to apply the AMC two-way coupling method to study the aerodynamic stability of vehicles.3.The main influencing factors of the aerodynamic stability of the vehiclesunder overtaking conditions are analyzed.The numerical simulation scheme of the high-speed aerodynamic stability of the vehicle under overtaking conditions is established and verified.Then the one-way and two-way coupling method under the different lateral spacing in the overtaking maneuver are studied,the influence of lateral spacing on the aerodynamic stability of the car in overtaking is analyzed,and the necessity of two-way coupling research on the overtaking problem is proved.Then the aerodynamic stability of overtaking process under different conditions are studied by AMC two-way coupling method.4.Firstly,the main influencing factors of the aerodynamic stability of the car under the meeting condition are analyzed,and the numerical simulation scheme of the high-speed aerodynamic stability of the car is established.Then the one-way and two-way coupling method under the different lateral spacing in the meeting conditions are studied and the numerical simulation scheme is verified.The influence of the lateral spacing on the aerodynamic stability of the car in meeting conditions with a coach is analyzed,and the significance of two-way coupling methods is proved.Then the AMC two-way coupling method is used to study the influence of the different relatives speed and absolute speeds,as well as crosswinds on the aerodynamic stability of the car meeting maneuver.