Research On Tire Aerodynamic Characteristics And Contour Optimization Method

When the vehicle speed reaches 60km/h or above,the aerodynamic drag will become one main source of the vehicle driving drag,and the energy consumption of the aerodynamic drag is more than 50%of the vehicle energy consumption.Therefore,reducing the aerodynamic drag of the vehicle is considered to be an important way to promote the development of energy-saving and environmental protection vehicles.When the optimal design of automobile drag reduction hits the bottleneck,the tire aerodynamic drag,which can accounts for up to 30%of automobile aerodynamic drag,will become the key point to break through the development of energy-saving,environmental protection and low aerodynamic drag automobile.In this thesis,the passenger car tire 185/65R14 is taken as the research object.By virtual of the finite element analysis method,the deformation characteristics of the loaded tire are obtained.Then the 3D printing technology is used to reproduce the deformation characteristics of the loaded tire.After then,the wind tunnel test method is used to conduct the aerodynamic characteristics of the tire.On this basis,the deformed contour of the loaded tire is extracted as the simulation object,and the tire virtual wind tunnel model is established.The accuracies of SST k-ω,LES and DES turbulence models for tire aerodynamic characteristics are compared and analyzed.The results show that different turbulence models have significant influences on tire flow field,and the DES model is the closest to the tire surface pressure coefficient of the test results.Different tread patterns affect the air flow characteristics in the tire area,and this would have a significant effects on the vortex structure around the tire.By comparing the effects of vertical pattern,axisymmetric pattern and point symmetrical pattern on tire aerodynamic characteristics,it is found that the arrangement of transverse groove angle has a significant effect on tire aerodynamic characteristics.By analyzing the flow characteristics in the groove,it is found that improving the stability of the flow in the groove can reduce the wake vortex and the aerodynamic drag.The differences of vortex structure of tire under static and rotating conditions are analyzed.The influences of tire contours on tire aerodynamic drag and flow field structure are explored.The contribution degrees of different regions of tire contour to aerodynamic drag are obtained.Combined with the analysis of tire aerodynamic characteristics and flow characteristics,taking improving flow stability as the design concept,five parameters,which are the sidewall height H,tread radiuses of curvature R₁ and R₂,tread width L₂,shoulder radius R,are selected as the design variables.The Optimal Latin Hypercube method,Kriging Approximation model and Adaptive Simulated Annealing optimization algorithm are used to optimize the tire contour structure,and based on the virtual wind tunnel model to compare the tire and automobile aerodynamic drag changes before and after tire optimization.The results show that the optimized tire contour can effectively improve the wake structure of the tire,and reduce the flow separation,thereby improve the wake of tire and the vehicle,and reduce the tire aerodynamic drag,and improve the car aerodynamics characteristics.