Drag-reduction Characteristics Of Form Bionic Combination Vehicle

Due to restrictions of the body structure,layout and ergonomics,etc,the overall shape of the combination vehicles must be presented in the form of square boxes,and thus its pneumatic resistance coefficient is generally high.China’s combination vehicle holdings increased year by year,the corresponding energy and environmental issues have gradually become a heated issue.The positive pressure in the front of the cab and the negative pressure in the rear of the cargo are the main source of the differential pressure resistance of the combination vehicle.Therefore,it is important to improve the air flow structure of the two area to reduce the vehicle pneumatic resistance coefficient.In the design of the transportation,the method of reducing the aerodynamic resistance is often achieved by bionic design.But in the field of automotive design,the research object of bionic design is more confined to the passenger car.Aiming at the key position of the pneumatic resistance of the combination vehicle,like the cab front end,gap between the cab and container and the rear of the vehicle.The feasibility of the pneumatic resistance reduction of the combination vehicle is discussed in this paper from bionic design,focusing on the analysis of aerodynamic characteristics of the combination vehicle after bionic design.The main contents of the paper are as follows:(1)Numerical simulation of the original models of combination vehicle and verification of wind tunnel experiments.Based on a Simplified digital model of a combination vehicle,the numerical simulations under different velocities were carried out by using the Reynolds-averaged method SST k-ω model.Based on the wind tunnel test,the measurement of the indexes of the same flow velocities are carried out by using the balance force method,and the PIV method respectively.It is found that the simulation results are in good agreement with the simulation results,and this validated the accuracy and creditability of the numerical simulation method used in this paper.(2)Extraction of bionic form.Based on the shape proportion and styling style of the combination vehicle The side-looking shape of the cheetah’s head and the back profile are used as the prototype of the vehicle bionic design.The curves of the two parts were respectively extracted,simplified and evolved to suit the subsequent cab and box shape design.(3)Research on aerodynamic characteristics of bionic cab in combination vehicle.The extracted cheetah head side profile is applied to the flat head cab design,to form the ‘Vehicle Nose’ cab shape in which the original engine compartment position protrudes forward.It was found that the convex position formed a vortex,which had a ‘Vortex Cushion’ effect on the upper airflow.This phenomenon reduced the area of the positive pressure zone and the pressure value of ‘front face’,and also reduced the aerodynamic drag coefficient of the combination vehicle The influence of the length of protruding part,the angle between the convex part and the A column on the aerodynamic drag of the model is studied too.(4)Research on aerodynamic characteristics of bionic streamlined container for combination vehicle.The back profile of the cheetah is applied to the GTS model container design.Carry on the numerical simulations to obtains the reasonable shape parameter and the drag reduction effect preliminarily.According to the results of GTS model verification test,design the bionic streamlined of the container of combination vehicle and conducted the numerical simulations.The study found that the streamlined top of the container design can effectively control the air separation,diminishes the degree of separation,reduces the resistance of the low pressure zone in the tail of the container,decreases the pressure drag,and also reduces the aerodynamic drag coefficient of the combination vehicle(5)The overall bionic design of the combination vehicle.After the verification of drag reduction of bionic combination vehicle design.The shape of the cheetah’s eyes profile and the black lines beside the corner are extracted,simplified and evolved with the guidance of Visual Dynamics.The inlet profile,inlet grille style,and lights are all designed with the reference of original combination.The vehicle styling method combined with the bionic design and the Visual Dynamics is feasibility.