On the Aerodynamics of Rear of Vehicle Model with Active Control by Blowing: Computational and Experimental Analysis

Abstract

Aerodynamics related to the generation of drag due to flow separations that occurs at rear parts of vehicles is an important consideration in vehicle design. It includes flow separation, wake formation, and pressures, which, in this paper, are focused on the ones exerted on the model’s rear wall. The pressure reductions could differ significantly between vehicles’ front and rear walls. This pressure difference can generate a phenomenon of backward pull and an increase in drags. The effort to minimize backflow as well as to cater increasing pressure on vehicles’ rear wall can be achieved by applying active control, including attached blowing apparatus. The paper presents the analysis of the effect on the application of blowing active control on the aerodynamics on rear part of vehicles, which is represented by a modified Ahmed body, reversed in flow direction and altered dimensions. The research was conducted using a validated numerical simulation method with laboratory experiments at an upstream air speed of 16.7 m/s and blowing velocities of 0.5 m/s, 1.0 m/s, and 1.5 m/s. The results showed that the application of blowing active control was capable to reduce aerodynamic drag, with the highest decrease achieved in the model with a ratio of velocity UBL3/U0=0.09 of 12.187% for the computational method and 11.556% for the experimental one.