Abstract:

ESDU 79026 gives curves obtained by correlating experimental data drawn from a wide range of sources in the literature. The graphs give the drag in uniform two-dimensional flow of regular polygonal sections with from four (square-section) to 20 sides, single- and double-wedge sections, elliptical sections and a 12 sided elliptical section. The effect of corner rounding between the extremes of sharp-edged to the inscribed circle is considered. Factors are included to correct the data for turbulence (and a table gives values of the appropriate turbulence parameters in a wide range of conditions both atmospheric or in internal flow), the effect of aspect ratio, and the effect of shear flow and taper. A method of calculating the centre of pressure and hence the overturning moment is also given. For the elliptical section, data are included for the situation when the section is not aligned with the flow. A comprehensive worked example illustrates the application of the data to a multi-sided pylon supporting a power cable.