SIMULATION OF THE GALLOPING VIBRATION OF A 2-DIMENSIONAL ICED CABLE SHAPE

Galloping of power transmission line conductors is a wind-induced vibration phenomenon not completely explained yet. One of the difficulties which delays a satisfactory and complete explanation is that the ice accretion shape and direction are random but at the same time are critical to the onset of the vibration. For the purpose of studying the galloping properties of different cross sections, a two-degree-of-freedom model of a typical two-dimensional shape was verified in a wind tunnel and also modelled numerically so that a computer simulation could be performed. Wind forces and moment are measured using a quasi-static approach and the expressed numerically as a function of the angle of attack. The model is developed using the bondgraph technique and includes the non-linear inertial coupling of the torsional and vertical forces and moment. The numerical simulation is obtained using a dynamic systems simulation program (TUTSIM). Results of the computer simulation agree with wind tunnel measurements in predicting galloping for a range of initial angles of attack. In these cases, the simulation shows that the inertial non-linear coupling between the rotational and vertical modes is not responsible for the initial instability resulting in galloping vibrations.