Drag reduction of a heavy vehicle using a modified boat tail with lower inclined air deflector

The improvement of the fuel efficiency of heavy vehicles has received considerable attention. Thus, various flow-control devices have been implemented to reduce aerodynamic drag exerting on heavy vehicles. In this study, we proposed noble boat tail with lower inclined air deflector (LIAD), as a passive flow-control device on attached at the rear end of heavy vehicles. The aerodynamic performance of the modified boat tail with LIAD is experimentally examined by measuring the drag force, side force exerting on a real-shaped heavy vehicle model at various yawing angles. As a result, the maximum drag reduction effect of the boat tail with LIAD (θ = 45°) is about 9.02% compared to the result without the boat tail, although the length of the bottom tail is half of that of four-way boat tail. Furthermore, particle image velocimetry velocity field measurements were conducted to investigate the modified flow structure are by the attachment of various boat tails. Consequently, the LIAD effectively suppresses the formation of large-scale recirculating zone in the wake behind the rear body of the vehicle, as an effective guide of the underbody flow.Graphical Abstract