Dynamic responses of a pair of circular tubes subjected to liquid cross flow

This paper presents the results of two experimental investigations of a pair of circular tubes subjected to liquid cross flow: (1) two tubes in a plane normal to the flow stream; and (2) two tubes in tandem. Tube response characteristics, including natural frequencies, damping, displacements and vibration orbits, are measured and reported. Results of this study provide additional insight into the interaction of pairs of tubes in liquid flow, including such phenomena as flow velocity-dependent damping and the frequency “lock-in” region of tube motion in the drag direction.