Flow characteristics over a tractor-trailer model with and without vane-type vortex generator installed

•Flow separation over tractor-trailers might be control using vortex generators.•VGs installed at the trailer front show stronger effects in affecting the wake flow.•VGs installed at the trailer back show limited effects in affecting the wake flow.•The size of wake vortex in tractor-trailers might be controlled by vane-type VGs.

An experimental study has been conducted to investigate the effects of vane-type vortex generators in affecting the flow pattern of the wake region using a 1:20 scale tractor-trailer model. The de Haviland wind tunnel of the University of Glasgow was employed in this study. Surface oil flow visualisation, smoke visualisation and two-component time-averaged particle image velocimetry measurements were used for flow diagnostics. Experimental data showed that putting the vortex generators near the front end of the trailer model could reduce the size of the vortex in the wake region. In addition, it was observed that the use of the vane-type vortex generators at the front of the trailer model might change the shear layer angle so that a smaller wake region was formed downstream of the trailer. No obvious effects of wake flow control could be observed by placing the vortex generators near the rear end of the trailer model. Finally, it was found that the vane-type vortex generator with the vane height of 6 mm is more effective in achieving wake flow control than the one with the vane height of 4 mm.