The aerodynamics involved in the galloping of lightly-iced transmission lines were studied in a series of wind tunnel experiments. A representative section of a lightly-iced conductor produced in an outdoor freezing rain simulator was used throughout. In the first set of experiments aerodynamic loads were measured on a static model at different wind speeds and angles of attack. These experiments showed that the well-established den Hartog criterion does not predict an instability at wind speeds associated with transmission line galloping. A second set of experiments examined the effects of different steady rotational motions on the aerodynamic loads. Automated controls were used to rotationally oscillate the model in a repeatable manner at various angles of attack and rotational amplitudes as well as frequencies. The drag remained consistent with quasi-steady values, while the lift was affected by the rotational motion. This rotation-induced lift was enhanced by ice surface irregularities, but further studies were needed to fully assess its importance.

This content is only available via PDF.
You do not currently have access to this content.