Optimization of aerodynamic braking systems in high-speed transportation vehicles

In this study, unlike previous research in the literature, the change of drag coefficient depending on the distance change with 3 different plates of (thickness)x(height)x(width) dimensions of (0.2x2x50), (0.3x3x50) and (0.5x5x50) cm respectively was investigated at speeds of 15, 20, 25 and 30 m/s in a closed system wind tunnel test chamber of (50x50x100) cm. The designed single-axis drag force measurement device was used to measure the drag force generated by the empty system, followed by the drag force generated by a single plate. Then, two plates were placed in the system, and the change in drag force was examined depending on the distance between them. The wind tunnel test chamber was 100 cm long, the distance between the plates was a, and the plate height was h. Using the distance change a/h = 0-1-2-3…45, the drag force was measured by placing double plates at distances up to a/h = 18 for 0.5 cm thick plates, up to a/h = 30 for 0.3 cm thick plates, and up to a/h = 45 for 0.2 cm thick plates. The study concluded that, in line with literature, the drag force increases with increasing plate height. The drag force is affected by the change in plate spacing, decreasing continuously from a/h=0 to a/h=6, and increasing continuously after a/h=6. At a distance of a/h=11, the double plate drag coefficient barely reaches the drag coefficient of a single plate. In other words, it was observed that a double plate placed at a/h=11 and before did not generate as much aerodynamic drag as a single plate. On the other hand, it was observed that the drag force of the double plate increases continuously from a/h=11 to a/h=45. Experiments were conducted up to a/h=45 due to the dimensions of the wind tunnel test chamber. This study is expected to contribute significantly to aerodynamic braking optimization studies, particularly in high-speed transportation vehicles.