DIYALA JOURNAL OF ENGINEERING SCIENCES

Abstract

Improving road vehicles performance needs to deep understanding the science of aerodynamics, in order to control flow field by means of active and passive control techniques. The airflow behavior when passes over the road vehicles surfaces will be changes in patterns and resulting in different pressure regions. This pressure region causes drag force and thereby increases in fuel consumption of the road vehicles.
This paper include experimental study to investigate the effect of road vehicles for three most common rear end configurations design such as (square, notch and fastback) on drag force, drag coefficient and pressure distribution. The experiments were carried out an open, low speed, and three dimensional wind-tunnel, on geometrical similarity to the prototype (Audi 80 1987) in scale down (1:18) wooden models for four different velocities (11.31, 13.86, 17.89 and 22.98) m/sec.
The results obtained from the wind-tunnel investigations showed that the drag force increases with the increasing of free-stream velocities. The minimum drag coefficient can be achieved with fastback configuration, comparing with the other tested models and result in approximately 16% and 48% lower than that for notch and square back configurations, respectively. These results are demonstrated by the pressure distribution curves which provide a deep understanding of the flow behavior above the tested models.