Research Of Aerodynamic Drag Reduction Of Van-body Truck Based On Porous Media

In today’s society of promoting energy-saving and emission reduction, the drag reduction technology research of truck is significant important. With the rapid development of highway transportation in our country, highway truck speed increases continuously. Fuel consumption of high speed truck is mainly used to overcome aerodynamic drag, which makes the drag reduction technology research vital. Arranging the porous media on the surface of the truck container to research aerodynamic drag reduction solutions will effectively improve the fuel efficiency, and achieve energy savings and reduce emissions.The research mainly includes the following four sections: the first section explores the method of simulation, design experiment to obtain the parameters for numerical simulation of porous media; the second section simulates the three-dimensional model of simplified truck with the arranged porous media on the surface of the container; the third section analyzes the effect of porous media on the flow field, studying the mechanism of drag reduction; the fourth section applies the best drag reduction scheme to the real truck model, and is verified via wind tunnel test.Based on the porous media module of FLUENT, the simulation method is studied by adopting a two-dimensional square column model in the first section. The simulation parameters can’t be obtained from the database directly. In order to solve this problem, the impeller and PSI pressure scanning equipment are used to conduct an experiment, through which the velocity data of the air across the porous media and pressure drop data are obtained. Then the simulation parameters are calculated by mathematical method. Via the comparison with previous scholars’ simulation results, the feasibility of the simulation method is confirmed.The second section is to analyze 75 simulation cases of various porous material arrangements on the surface of the truck container. The 75 simulation cases are combined by three kinds of porous material properties, five kinds of positions, and five kinds of porous material thicknesses. Numerical simulation results show that the optimal scheme of drag reduction rate is 11.26%, via arranging fiber material with 40 mm thickness on the top surface of the container. By data analysis, the connection and affiliation between the drag reduction rate and material properties, positions, material thickness are obtained.In the third section, the effect of porous media on the flow field around the truck is analyzed and the drag reduction mechanism of porous materials is explored. The drag reduction mechanisms of five positions are not identical; however, the drag reduction mechanisms of different thicknesses and different material properties are similar. Hence, the focus is the effect of positions on the flow field. The post-processing shows that: 1.The porous media makes the wall shear stress decrease significantly; therefore, the viscous friction decreases. 2. Porous media changes the pressure distribution around itself, thereby affecting the pressure field of the whole truck. 3. Porous media can reduce the separation of the vortex scale on the top and side surfaces of the container, so that the flow reattaches ahead of time and suppresses the effect of the vortex.The best drag reduction scheme is applied to the real truck model, and the numerical simulation result is verified by wind tunnel test in the fourth section. The error between experiment and simulation is within the permissible error, so the reliability of the numerical simulation is verified.By the method of numerical simulation and wind tunnel test, the effects of all parameters of the porous materials on the drag reduction rate are obtained. The effect of porous media on the flow field around the truck and the mechanism of the drag reduction are discussed. The best drag reduction scheme is applied to the scale model of a real truck; the numerical simulation is verified by wind tunnel test. It provides some guidance for the application of porous media on aerodynamic drag reduction of high-speed truck.