Experiment And Simulation Research Of Vehicle Aerodynamic Lift

With the rapid growth of high-grade highway traffic mileage, the average speed ofautomotive is greatly improved. Vehicles are often “waving” at high speed, the directreason for “waving” is that aerodynamic lift hold up the vehicle perpendicular to theground overcoming the gravity which making the adhesiveness worse. As one of themost important evaluating indicator of aerodynamic performance, aerodynamic lift notonly directly affects the safety of the automotive, but also indirectly affects theautomotive’s fuel economy. So the aerodynamic lift coefficient is very important in theprocess of automotive aerodynamics design which influencing stability and safety ofvehicle.Through a large number of simulation and experiment, the effects of vehicleshape on aerodynamic lift are researched and a real car is optimized. Then, parametersof wind tunnel suction system are optimized to enhance the suction effect of suctionsystem. At last, the transient characteristics of aerodynamic lift are investigated whichprovide a reference for the study of transient motion of vehicle. Therefore, starting theexperimental and computational study on aerodynamic lift is not only of greattheoretical significance, but also conducting the project development.First of all, CFD methods are applied to investigate effects of different shapes ofthe bottom and rear of vehicle on aerodynamic lift. Velocity stream line and pressuredistribution of different vehicle shapes are obtained to research the relationshipbetween the structure of rear wake vortex and aerodynamic lift.Secondly, this paper introduces modem optimization algorithm to theoptimization of wind tunnel suction system. Based on the original suction system, thethickness and porosity of ground and the suction rate of suction system are optimizedthrough the method combines with the approximate model and genetic algorithm. Afterthat, the thickness of boundary layer is reduced, the effect of suction system isimproved, and wind tunnel test is more accurate.Thirdly, the seal plate, spoiler lip and non-smooth surface are applied on thebottom of “ZhongQi” model so that aerodynamic lift of the model is improved and thehigh-speed driving stability of the model is raised.Finally, at present, the research condition on aerodynamic lift is almost steadyinlet, but the wind speed in the nature constantly changing, that makes the aerodynamic lift pulse diversification. LES method is applied to study transientcharacteristic of aerodynamic lift under the unsteady inlet condition.In this paper, many kinds of additional devices are designed to make vehicles witha low drag and lift. And then optimum combinations of wind tunnel suction systemparameters are proposed. Finally, this paper reveals the transient characteristics ofaerodynamic. This will not only provide a reference for automotive shape designingand modification, but also can help to understand the transient aerodynamiccharacteristic so as to provide a theoretical basis for the automotive safety andautopilot technology. Meanwhile, numerical optimization methods can be applied toautomotive wind tunnel designing so that it can save cost and reduce developmenttime.