Study On Influence Of The Flow Field Around Wheels To The External Flow Field Around Vehicle Based On A SUV

With the increasingly stringent fuel consumption regulations,the study of automotive aerodynamics is increasingly important.The wheel as an important part of the vehicle,has a great impact on the aerodynamics force,the contribution of wheels for the aerodynamic drag force of the streamlined car is even more than 50%.Firstly,studying the flow field around wheels can help people to understand the distribution of the flow field around wheels and know its influence to the vehicle.Secondly,it can help people to optimize the flow field around the vehicle and enhance the level of aerodynamics characteristic of vehicle.In this paper,the main study method is numerical simulation.Firstly,using CATIA to carry out the reverse engineering to get the 1:1 model,then,using HYPERMESH to divide the surface meshes,last,using STARCCM+ to set the boundary conditions,generate the volume meshes and finish calculating the model.To ensure the accuracy of numerical simulation,the results of numerical simulation are compared with the experimental results.The results show that the model is accurate.Secondly,the difference of the flow field around vehicle in conditions of rotating wheels and static wheels is analyzed,this study shows that rotating wheels effect the flow field around vehicle,especially effect the local flow around wheels,the flow field of bottom and tail.Comparing to rotating wheels,the coefficient of drag and lift of static wheels is bigger.Finally,according to the analysis of local flow field of wheels,the seven factors that effect the flow field around wheels are determined and their levels are also ascertained,The uniform design experiment method is used to design thirty different models and the simulation calculation is carried out.In the process of establishing models and simulation calculation,the methods of CATIA secondary development and Windows batch processing is used,these methods are simplified the flow progress of the study.MINITAB is used to analyze the influence of different factors for aerodynamic drag coefficient and search the best parameters for the original model.The best model is established as the best parameters and it is calculated.Compare the original model with the best model,the aerodynamic drag coefficient of the vehicle is reduced about 0.062,decreasing range is 15.9%,the study shows that the influence of the flow field around wheels to the external flow field around vehicle is big and aerodynamics drag reduction based on wheels can get the aim of drag reduction for whole vehicle.