Analysis Of The Wheel Structural Parameters And Its Aerodynamic Accessories Influence On Car Wind Resistance

With the increasingly serious problems of energy crisis and environmental pollution,energy saving and emission reduction have become the only way for the development of the automobile industry.When the car is running at high speed,the energy consumption used to overcome the wind resistance is as high as more than 50% of the energy consumption of the whole vehicle.Among them,the air resistance generated by the wheel accounts for 25% of the wind resistance of the whole vehicle.The wheel structure needs to be finely designed.However,the complexity of the flow field in the rotating wheel area and the lack of a high-precision simulation method to predict the flow field in this area make the design of the low wind resistance wheel mostly rely on the wind tunnel test method,which will greatly increase the development cost and cycle.This Paper aims to find out the high-precision simulation method of the external flow field of the vehicle with rotating wheels and the influence of the wheel structure and the wheel aerodynamic kit on the wind resistance of the vehicle,so as to provide guidance for the refined design of the wheels with low wind resistance.It is of great engineering significance to promote the development strategy of energy saving and emission reduction of automobiles.First,based on the CAERI Aero Model 1:1 sedan-back vehicle model,Numerical simulation and wind tunnel test were used to compare the simulation accuracy of Realizable k-ε URANS,SST k-ω URANS,LES,and DES four unsteady turbulence models on vehicle aerodynamic drag,body surface pressure,and wheel regional cross-section flow field.Compare the ability of steady-state and unsteady RANS methods to capture the contribution of vehicle wind resistance.Then,based on the surrogate model method,the influence of rim closed gap,wheel width and rim diameter on the wind resistance of the vehicle is studied.Finally,the CFD model of the whole vehicle with rotating wheels established in this Paper is used to study the influence of the front wheel spoiler,air curtain and wheel arch cover on the wind resistance of the whole vehicle.The function principle and drag reduction effect of full-encircle,semi-encircle and wedge-shaped front spoiler are analyzed.The function principle and drag reduction effect of the air curtain are analyzed.The influence of the distance D between the wheel and the inner wall of the wheelhouse on the wind resistance of the vehicle is discussed.The drag reduction effect of designing the chamfer structure at the end of the wheelhouse is discussed,and the influence of the chamfer size L on the wind resistance of the vehicle is studied.The results show: The steady-state simulation method using the MRF+RW hybrid rotation simulation method and the Realizable k-ε turbulence model can meet the accuracy requirements of solving the vehicle wind resistance contribution,and improve the calculation efficiency.When the rim closed gap D2=30mm,the wind resistance of the whole vehicle is the smallest,and with the increase of the rim closed gap,the wind resistance increases.With the increase of the wheel width,the wind resistance of the whole vehicle shows an upward trend.When the rim diameter is from 14 " to 15" wind resistance is reduced.However,when the rim diameter is from 15 " to 21",the variation law of wind resistance will vary with the wheel width W.When the wheel widths are W=175mm,W=185mm,and W=195mm,the wind resistance keeps increasing.When the wheel width is W=205mm,W=215mm,W=225mm,W=235mm,the wind resistance keeps increasing for the rim diameter increases from 15 " to 18".The wind resistance keeps decreasing for the rim diameter increases from18 " to 21".The wedge-shaped front spoiler has the best effect and can reduce drag by5counts;After installing the air curtain,the drag can be reduced by 7 counts;The distance D between the wheel and the inner wall of the wheel arch will affect the flow field under the vehicle,thereby affecting the aerodynamic resistance of the chassis and rear wheels;With the decrease of D,the wind resistance of the whole vehicle shows a decreasing trend;The chamfered structure at the end of the wheel arch can effectively reduce the wind resistance of the vehicle.With the increase of the chamfering depth L,the wind resistance of the whole vehicle first decreases and then increases.When the chamfering depth L=40mm,the wind resistance of the whole vehicle is the smallest.