Design of an experimental arrangement to study the wind loads on transmission towers due to downbursts

摘要

High intensity winds (HIW) are associated with severe wind loading patterns on transmission lines and tower failures. These HIWs namely tornadoes and downbursts, are often short-lived, highly energetic, flow fields that are difficult to reproduce for investigative procedures. However, this work outlines an experimental facility for studying the behaviour and characteristics of a downburst in both still air and a cross flow. It is shown that the downburst model produces the three stages of a typical downburst, that is, the contact, an outburst and a cushion stage. The growth of the ensuing ring vortex is captured and initial measurements shows that it expands faster in the radial sense than vertically. In addition to the experimental studies, a finite element analysis has been performed on two geometrically different towers. Although the work is still in progress, early results show that a heavier pylon type of tower is less likely to be affected by non-linearity, whereas a lighter weight, guyed, type of tower may be subjected to buckling modes of failure.