An experimental study of rime ice accretion on bundled conductors

The dynamic ice accretion process on bundled electrical power conductors and icing-induced effects on the aerodynamic forces acting on the conductors were examined experimentally. An Icing Research Tunnel was used to generate a typical atmospheric rime icing condition experienced by power transmission cables. Two pieces of Aluminum-Conductor-Steel-Reinforced (ACSR) cables were mounted in the icing wind tunnel with different spacing and angular displacements with respect to the incoming airflow. While ice accretion was found to take place primarily on the frontal surfaces of the bundled conductors, the accreted ice layers resembled well the twisted outer strands of the ACSR conductors. Averaged outer profiles of the iced conductors were elliptical with the semi-minor axis being the radius of the conductors and the semi-major axis passing through the foremost frontal points of the accreted ice layers. The icing process on the windward conductor was almost unaffected by the existence of the leeward conductor. The ice accretion and resultant aerodynamic force acting on the leeward conductor were found to vary significantly, depending on the spacing and angular displacements between the bundled conductors. The windward conductor was found to induce a "shadowing effect" by intercepting airborne supercooled water droplets to prevent them from impinging onto the leeward conductor, resulting in much less ice accretion and smaller aerodynamic drag acting on the leeward conductor. The aerodynamic force measurements were correlated with the acquired ice accretion images and wake flow field around the bundled conductors to elucidate the underlying physics.