In this study the aerodynamic characteristics of 1/32 scale truck and trailer model were examined in a wind tunnel. The acting drag force to model truck and trailer combination is calculated and aerodynamic drag coefficient is determined. The wind tunnel tests were carried out in the range of 159 000 -453 000 Reynolds numbers. In order to improve the aerodynamics structure of truck-trailer, one spoiler, one passive air channel and three different redirector is produced in three dimensional printer. These aerodynamic parts respectively added to base truck-trailer model and obtaining aerodynamic improvement rates compared. According to wind tunnel test results, the aerodynamic improvement rates are respectively 14.78%, 18.06%, 23.15%and 20.70%. The lowest drag coefficient was determined as 0,584on model-3 of truck-trailer model.

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