Research On Aerodynamic Characteristics And Stability Of Vehicle Under Crosswind Effects

When the vehicle runs at high speed,it is easily affected by the crosswind.The crosswind changes the flow field around the body,destroys the symmetry of the flow field,changes the aerodynamic force and torque of the vehicle,and have a great influence on the handling stability and safety of the vehicle.Dangerous behavior can even cause traffic accidents.At the same time,the streamlined and lightweight of the car shape increased the crosswind sensitivity of the car.Therefore,studying the stability of vehicle under crosswind is of practical significance for improving the active safety of vehicle.In this paper,based on the principle of relative motion,the research scheme of the aerodynamic characteristics of the automobile is determined.Based on the LBM numerical simulation method,we obtain the six component parameters of the flow field and aerodynamic force.A parameterized vehicle dynamic model is set up,and the aerodynamic six force coefficient obtained in the study of aerodynamic characteristics is carried out in the open loop,closed loop and multi condition virtual experiments.The stability of the vehicle under the influence of the crosswind is analyzed and evaluated,which provides a reference for the comprehensive prediction of the impact of the crosswind on the stability of the car.And doing simulation research on vehicle crosswind handling stability based on active control model.The calculation results show that:1.The aerodynamic six component force increases with the increase of crosswind speed,which affects the acceleration performance,fuel economy,handling stability and driving safety of vehicle.The larger the crosswind speed,the more turbulent the flow field around the car body is,the more vortex is generated,resulting in the change of aerodynamic six components.2.When vehicle runs in the straight line,the aerodynamic side force and yaw moment will change the original driving track and the lateral force of the tire.they have a negative impact on the tire wear,which leads to the driving maneuverability and affect road traffic safety.The influence of aerodynamic roll moment on vehicle not only changes the lateral velocity,but also makes the overturning of vehicle during the driving process.3.The driver model will be beneficial to the stability of the vehicle crosswind and improve the driving state of the car.But the driver's preview time should not be too short,which will increase the possibility of vehicle overturning in the crosswind.4.The larger the vehicle speed and wind speed is,the larger the vehicle's lateral offset distance is,the more the vehicle will shake,which will increase the possibility of vehicle overturning.Increasing speed in the side wind will reduce the driving stability especially in severe gusty wind.The more severe the gust changes,the greater deteriorative the stability and safety of the vehicle will be,the higher the swing frequency of the body is.The results of Joint simulation test show that active safety control technology can effectively improve vehicle handling stability.In conclusion,the influence of the side wind on the aerodynamic characteristics of the vehicle and its influence on the vehicle handling and stability is revealed in this paper,which provides an important reference for the deep-study of the stability of the automobile side wind.