Flow-induced vibration of an inclined flexible cylinder in tandem arrangement

Flow-induced vibration (FIV) of a flexible inclined circular cylinder placed in the wake of a stationary cylinder is studied, experimentally. A highly flexible circular cylinder with an aspect ratio of 47 and a mass ratio of 120 was held fixed at both ends and placed inclined at 45° to the incoming flow in the test-section of a subsonic wind tunnel. The inclined flexible cylinder lied in the wake of an upstream stationary cylinder of equal diameter and inclination. The dynamic response of the downstream cylinder is studied for center-to-center spacing range from 3 to 7 times the cylinder diameter, in the reduced velocity range of U*=3.6-48.5 and the Reynolds number range of Re = 260-3750.

The validity of the independence principle, which states that the behavior of an inclined cylinder is essentially driven by the normal component of the incoming flow velocity, has been previously investigated for a single flexible cylinder. The objective of this study is to examine the effects of inclination on FIV response of cylinders in tandem arrangements. Dynamic response of the inclined flexible cylinder in terms of the excited structural modes, frequencies of oscillations, and modal weight contributions is compared to those of a normal incidence flexible cylinder in tandem arrangement.