Dynamic characteristics of marine risers conveying fluid

The lateral vibration differential equation for a marine riser conveying fl uid is derived by use of the small deflection theory, and the effect of int ernal flow velocity and top tension on the natural frequency of the riser i s studied by use of FEM. At the same time, the preliminary relationship bet ween the natural Frequency and riser span under different internal flow vel ocities is obtained, the effect of riser supports on the vibration frequenc y is computed. It is found that the natural frequency of the marine riser i ncreases with the increase of top tension, however decreases with the incre ase of internal flow velocity. In addition, the Frequency decreases drastic ally with the increase of riser span.