EXPERIMENTAL STUDY ON VORTEX INDUCED VIBRATION OF SUSPENDED SUBMARINE PIPELINE

Based on the requirements of the hydroelastic similitude criteria, experiments have been conducted on the vortex induced vibration of flexible suspended submarine pipelines with common flow velocities and suspended span heights of in-service submarine pipelines. The strain was measured by strain gauges bonded on the inner surface of the pipeline. The result of Vr <3.0 reveals that the vortex induced vibration of flexible suspended pipelines increases with the increasing of a reduced velocity, Vr, for all experimental gap-diameter ratios, and the vortex induced vibration of flexible suspended pipelines has a rapid reinforcement when the reduced velocity, Vr, is near 2.0. And the vortex induced vibration of flexible suspended pipelines does not vary with the relative span height, e/D, monotonously. The vibration of suspended pipeline is dominated by a vortex shedding frequency and is not affected by the relative span height, when relative span heights are greater than 0.4. And the vibration of suspended pipeline is dominated by the pipeline natural frequency at which the relative span height equals 0.4. Moreover, Strouhal number is near 0.18, calculated by using the dominant frequency of vibration at which the relative span heights is greater than 0.4.