Effects of Vehicle Types on Aerodynamics of Three Vehicle Platooning

Abstract:

The effects of three MIRA bodies， i.e.， squareback， fastback， and notchback， on the aerodynamic resistance of three vehicles in platooning are numerically explored at one-vehicle spacing. A detailed analysis of the resistance of the whole vehicles and individual parts as well as inter-vehicle flow under 27 different platooning configurations shows that the back pressure of the head vehicle rises due to the blockage of the middle vehicle. All three types of head vehicle can achieve resistance reduction for themselves. The resistance of the middle vehicle will be affected by the back pressure rebound， weakening of the front positive pressure and front edge arc negative pressure due to the combined effect of the head， middle， and trailing vehicles. Thus， some cases of the middle vehicle in platooning have a low resistance and some have a high resistance. The pressure and resistance changes of the trailing vehicle is similar to those of the middle vehicle in view of the combined effect of the middle and the trailing vehicle types. The low-speed wake region of the preceding vehicle is beneficial to the resistance reduction of the following vehicle， but it will also reduce the suction of the arc at the front edge of the following vehicle， which has a negative effect on the platooning drag reduction， and even increases the whole resistance. The best configuration of the three-vehicle platooning is the fastback head vehicle， squareback middle vehicle， and the notchback trailing vehicle with a resistance reduction of up to 0.12（120 counts）.

Key words:vehicles platooning;aerodynamic drag reduction, MIRA model;wake