Abstract: In order to reduce the aerodynamic drag coefficient of a van type truck, different types of bionic cab spoiler, tail fairing and bionic non-smooth surface structure are designed. Then their effects on the aerodynamic drag coefficient of the truck are analyzed, with their drag reduction mechanism discussed in detail. Finally, the overall drag reduction effect is studied with different drag reduction devices installed on the same truck model. The results show that the drag reduction effect of bionic cab spoiler is better than that of traditional one, and with the increase of the extension length of cab spoiler‘s side skirt, the drag coefficient of the truck gradually reduces. When the inclination angle of the lower deflector of tail fairing is around 45°, the drag coefficient of the model gets a minimum value. Based on the bionic drag reduction theory for biological surface, both semi-spherical pits and semi-ellipsoidal pits arranged on the side of the truck have good drag reduction effect. The combination of three types of drag reducing devices on truck model can get a drag reduction rate of up to 22.7%.

Key words: van type truck, bionic cab spoiler, tail fairing, bionic non-smooth surface, combined drag reducing device