Experimental investigation of the vortex-induced vibration of tapered light poles

Abstract

To investigate the vortex-induced vibration (VIV) of a tapered light pole with a weld, experimental tests were carried out using a simplified aeroelastic model and a static sectional model in a wind tunnel. The VIV characteristics and aerodynamic performance of the light pole were investigated with and without considering the weld on the surface. It was found that the light pole can experience second-order mode VIV and multi-mode vibrations at different incoming wind speeds. For the second-order mode VIV, the cross wind vibration amplitudes were approximately twice that of the along wind, and the motion trajectory exhibited a steady ellipse shape. For the multi-mode vibration, no stable vibration trajectory was observed in the time history, and the higher modes vibration tended to occur at higher wind speeds. The weld had a dramatic effect on the VIV characteristics and aerodynamic performance of the light pole. The weld could increase or depress the VIV of the light pole, depending on its position relative to the wind direction. Furthermore, the aerodynamic force, Karman vortex shedding, Strouhal number, and distribution of the wind pressure were highly sensitive to the weld position. Different flow patterns could be triggered when the weld is located in certain positions, which may eventually result in different aerodynamic performance of light poles in the field.