Research On The Effect Of The Underbody Structure Of Square Back Vehicle On The Contamination Of Rear Window

Rear glass of square back car is more easily contaminated than sedan.As square-back vehicles are becoming more and more popular,in recent years.It is necessary to analyze the mechanism of the rear glass contamination,control its occurrence and improve people's driving experience.In order to study the influence of the underbody structure of vehicle on rear glass contamination,the following three aspects of work were done in this paper:In the first part,the numerical simulation of the rear window pollution of the original model was carried out.And corresponding road experiment has been carried out to verify the numerical simulation.Then the mechanism of the rear glass contamination was analyzed in detail.According to the simulation,the bottom structure of vehicle is an important factor influencing the rear window contamination.And this conclusion paves the way for further research.In the second part,based on the conclusions obtained in the previous section,the ground clearance,the wheelbase and diffuser angle were selected.And design of experiments,numerical simulation and data mining were used to analyze the influence of the ground clearance,the wheelbase and diffuser angle on the rear window contamination and aerodynamic characteristics.From the analysis,these three variables and their interactions both have an impact on the target.There is a competitive relationship between the aerodynamic drag and the rear window contamination,and can not be optimized at the same time.The multi-objective optimization method was used to optimize the combination of these three variables.Three optimization objectives were selected.One is minimum rear glass contamination,other one is minimum aerodynamic drag,the last one is 0N lift force.According to the optimization results,a better parameter combination was selected to analysis the flow field.And the selected vehicle rear window contamination reduced by 56.5 percent,meanwhile the aerodynamic drag increased by only 0.32 percent.In the last part of the paper,two different fenders were selected and corresponding numerical simulation were carried out.And the influence of fenders on the rear window contamination and the aerodynamic performance was analyzed in detail.According to the analysis,the installation of the fender can control the rear window contamination of the car effectively,and improve the aerodynamic lift to a certain extent.While the aerodynamic drag of the vehicle is increased due to the installation of the fender.In this paper,the influence of the bottom structure of square back vehicle on the rear window contamination and aerodynamic characteristics is analyzed,which can provide some reference for the future vehicle design.