Experimental Investigation On Aerodynamic Characteristics Of MIRA Model Group In Wind Tunnel

Automotive aerodynamic characteristic, the premise and theoretical basis for theautomobile body styling, is not only an important indicator to evaluate automobileperformance, but also significantly affects the power performance, fuel efficiency,handling stability, comfort and safety of an automoblie. Currently, the wind tunnelexperiment is an important method of automotive aerodynamic reaearch. A largenumber of important results are obtained from the experiments. On account of thebasic research for automotive aerodynamics starting later, especially experimentresearch for aerodynamic characteristics in the wind tunnel, discuss about themechanism of aerodynamic coefficient change and the factors which influent the dataaccuracy, it has become one of main technological bottlenecks of constrainingautomotive research independence. Therefore, the research on wind tunnel experimentof automotive aerodynamics has very practical significance.In this paper, based on the test which is carried in HD-2wind tunnel in HunanUniversity, the research on the aerodynamic characteristics of three different tails ofMIRA models is done.To begin with, demonstrate the theory about wind tunnel test, such as types andconfiguration of wind tunnel, technical requirements for the wind tunnel test, thecorrect method of wall interference. Describe the test equipment, instruments and theirprinciple and instruction in detail.Then, measure the aerodynamic force and moment of the MIRA model group,analyze the superiority of aerodynamic performance of each model, and the measureddata was compared with domestic and foreign wind tunnel test data and calibrated;measure the pressure distribution of the model group in symmetry by ElectronicPressure Scanner Valve(EPSV). Analyze the distribution characteristics of thecoefficients of surface pressure on the model in symmetry; meanwhile, quantitativelymeasure the model external flow field in symmetry by Particle Image Velocimetry(PIV), compare the velocity and vortices characteristics of the rear part of the modelgroup, and analyze the cause mechanism of how the tail flow field influences theaerodynamic coefficient.Finally, the HD-2wind tunnel ground layer thickness and suction system areanalyzed, and the correction formula about HD-2wind tunnel ground layer thickness is deduced. The results of this paper help understand the influence and mechanism ofcar three classic tails on aerodynamic characteristics, significant to evaluate andoptimize the car tail modelling in the future.