Hydroelastic response of a circular tube in eccentric annular flows

Abstract

This paper describes an experimental study of the hydroelastic response of a tube located concentrically and eccentrically, respectively, in a circular water-flow channel. Acceleration components in two orthogonal directions were measured at the midpoint of the test element by using a pair of accelerometers. The investigation included determination of natural frequencies, damping factors, rms displacements, and the variations of these dynamic quantities with eccentricity and mean axial flow velocity. The experimental data were processed into statistical forms, including power spectral density function and rootmean-square values. The results show that the natural frequency of the tube shifts as the eccentricity or flow velocity increases, that the damping in flowing water is greater than that in stationary water, and increases with increasing flow velocity and eccentricity, and that the rms displacement increases as the eccentricity and/or flow velocity increases.