The experimental and numerical drag minimization of a bus model by passive flow control method

In this study, the drag coefficient of 1/33 scaled bus model were decreased by using passive flow control methods. The studies were conducted in wind tunnel and Computational Fluid Dynamics (CFD) method. The experimental tests were performed at 6 different free stream velocities (13.54 m/s ÷ 28.05 m/s), between the range of 3.8×105÷7.9×105 Reynolds numbers. The drawing data of bus model and flow control rod were obtained in SolidWorks program. Two different triangular flow control rods (D/H = 0.1 and 0.2) designed and mounted on the front of the bus model in the same L/H rates. The maximum drag reduction was obtained as 14.50% and 5.74% by using triangular structured flow control rod in wind tunnel. To determine detailed flow structure around bus model, CFD flow analyses were performed at the same wind tunnel conditions for base model bus and best result. Also the numerical flow analyses supports experimental results and drag reductions with 1–4% error margin. In this study, the maximum drag reduction was obtained as 14.50% in triangular flow control rod L/H: 0.15. This drag minimization decrease on fuel consumption is about 7% at the high vehicle speeds. Key words: aerodynamic, bus model, drag force coefficient, wind tunnel,CFD, RNG κ?ε turbulence model, fluent, Navier–Stokes, passive flow control method