Abstract:To study the applicability for designs of the offshore bonded oil pipeline, the hydrodynamic characteristics of the cylinder with various submerged depths are studied in the towing tank. In the experiment, three kinds of rigid cylinders with different diameters are used to simulate the oil pipeline. The trailer is towed at five different speeds, and the hydrodynamic force on the cylinder is measured at five different submerged depths. The Reynolds number range was 4.6 × 104 ~ 7 × 105. The experimental results show that there are great differences in drag force coefficients at different submerged depths. For the same kind of cylinder, the drag coefficient increases with the depth when the Reynolds number is constant. In addition, the phenomenon of "drag crisis" is observed in the experiment, which is related to the Reynolds number of the flow field. The drag coefficient obtained from the experiment has a certain guiding significance for the actual offshore oil engineering.