Fluidelastic response of a tube in eccentric annular flows

Experimental measurements are reported on the dynamic response of a circular cylindrical tube located concentrically and eccentrically in a circular water-flow channel. Acceleration components in two perpendicular directions are measured at the midpoint of the test element using a pair of accelerometers. The investigation includes determinations of natural frequencies, damping factors, and rms displacements, and the variations of the above dynamic quantities with eccentricity and mean axial flow velocity. The experimental data are processed into statistical forms, including power spectral density function and root-mean-square values. The results show the following: (1) the natural frequency of the tube shifts as the eccentricity or flow velocity increases, (2) the damping in flowing water is greater than that in stationary water and increases with increasing flow velocity and eccentricity, and (3) the rms displacement increases as the eccentricity and/or flow velocity increases