Effect Of Active Grille Shutter On Dynamic Characteristics Of Hybrid Vehicle

Active grille shutteris the optimization of traditional intake grille.While inheriting the full functions of the former,it has become the choice of more and more automobile manufacturers because of its flexibility and better adaptability to different working conditions and environments.Active grille shutter can actively select the angle of opening and closing by sensing the vehicle's driving information,such as speed and distance,so as to reduce the driving resistance of the vehicle,improve fuel economy and handling stability.By comparing the aerodynamic performance indexes such as aerodynamic drag and aerodynamic lift under two critical conditions of the opening and closing of the intake grille of a vehicle,this paper obtains the influence of the active closing of the intake grille on the dynamic performance,handling stability and other factors of the vehicle under complex conditions,such as meeting and overtaking,and obtains the optimal control strategy of the opening and closing of the intake grille,that is,the optimal control strategy of the opening and closing of the intake grille.For different speeds and different working conditions,the intake grille can be actively closed to ensure the safety of the vehicle.Firstly,the transient numerical simulation of a van truck traveling at 33m/s speed is carried out to obtain the variation law of its aerodynamic parameters and the distribution of the flow field around the body.By comparing with the experimental data of the predecessors,the feasibility of the research method is verified,which lays a foundation for the selection and comparative analysis of the follow-up research methods.Using the same numerical simulation scheme as above,the transient numerical simulation of the car intake grille opening and closing conditions is carried out respectively.When the aerodynamic coefficients are different,the following conclusions are drawn:the closing of the intake grille can reduce the vehicle drag coefficient by 13.8%and lift coefficient by 15.1%.The sliding interface and dynamic mesh technology are used to simulate the variation of aerodynamic parameters and the flow field distribution of the vehicle when the intake grille is opened and closed,and the vehicle passes ahead at 120 km/h and 60 km/h respectively.The results show that when the vehicle exceeds 1.5 times the length of the truck,the aerodynamic drag coefficients of the truck reach their peak values When the intake grille is closed,the drag coefficient,lift coefficient and lateral force coefficient will decrease by 16%,24%and 20%respectively.The theoretical analysis shows that,compared with the opening of grille,the closing of grille will increase the steering wheel load by about 2%due to the reduction of lift coefficient.At the same time,the closing of grille will reduce the lateral force by 20%at the dangerous time of overtaking.Considering the sideslip characteristics of the tire,the closure of the intake grille will reduce the sideslip angle of the tire by about 23%.Using the same method,the influence of grille closure on the aerodynamic coefficients of vehicles at dangerous time of meeting is studied.It is found that the dangerous time of meeting occurs when the distance between two vehicles is zero.Closing the grille will reduce the lift coefficient and the lateral force coefficient by 0.18.5 and 0.33,respectively,and make the sideslip angle of the vehicle affected by the lateral force relative to the grille opening.Down 34%.This paper mainly studies the opening and closing state of the intake grille and its influence on the main aerodynamic characteristics of automobiles in complex conditions such as meeting and overtaking.It summarizes the changing law of the aerodynamic coefficients under various conditions.It is proved from numerical simulation and theoretical analysis that the use of the active grille shutter improves the active safety of automobiles,which not only makes the active safety of automobiles more diversified,but also makes the active safety of automobiles more diversified It provides a basis for integrating it into the automatic driving system.