Flow control devices for drag reduction in ground vehicles: DrivAer with fastback configuration

Abstract

Nowadays, the shortage of fossil fuels and the effects of their consumption on the environment make it necessary to optimize the aerodynamics of vehicles in order to minimize fuel consumption and CO2 emissions. This is the reason why this project studies the aerodynamics of the generic DrivAer model, adding passive devices to reduce its aerodynamic drag and therefore fuel consumption and CO2 emissions. The model chosen to carry out the study is the fastback DrivAer with smooth underbody, and the simulation conditions are without moving ground nor wheel rotation. The Reynolds with which the simulations have been performed is 4.87M, using the RANS method with the k-omegaSST turbulence model. The model has been validated with an error of less than 4% by comparing the results with other experimental and numerical studies. The passive control elements added to the base geometry are a rear low spoiler configuration and two deltashaped vortex generators configurations, one placing 11 units in parallel and the other placing 10 pairs of vortex generators tilted 15 degrees right and left consecutively with respect to the car’s plane of symmetry. The rear spoiler reduces drag by 7% and the set of vortex generators up to 2%. With both mechanisms applied to the car, the aerodynamic drag reduction achieved is 7.5%.