An experimental study on drag coefficient of a cam-shaped tube with different aspect ratios

An experimental study has been conducted to show the effect of aspect ratio on pressure drag of a cam-shaped tube in cross-flow of air. The aspect ratio varies between 1.35 ≤ L/D ≤ 3.13 and Reynolds number based on equivalent diameter changes in the range of 2.5×103 to 5.5×103. Studies were carried out at the angles of attack of 0 and 180 degrees. Results show that by increasing the aspect ratio, the drag coefficient decreases. The drag coefficient at the angle of attack zero degrees is about 54 to 82 percent lower than the circular tube with the same equivalent diameter. Also, the drag coefficient at the angle of attack 180 was about 42 to 82 percent lower than the circular tube with the same equivalent diameter. It was found that the cam-shaped tube with L/D=3.13 has a minimum drag coefficient which is about 82% lower than a circular tube with equivalent diameter.