Measurements of Fluctuating Air Loads on a Circular Cylinder

Measurements were made of the unsteady air loads, both lift and drag, developed on a circular cylinder when exposed to flow in the supercritical Reynolds number range from 0.38 x 106 to 0.75 x 106. The three dimensional nature of the flow, which is a consequence of the flow separation effects, is recognized. The statistical character of spatially varying random type fluctuating air loads is presented in the form of cross-spectral densities and cross-correlation coefficients. Information of this type has application to the problem of determining the response of a cylindrical structure when exposed to air loads. The extreme sensitivity of the flow to surface irregularities in the supercritical Reynolds number region is reported including the effects upon the local and spatial character of the fluctuating loads. Local values of steady state lift could be induced by suitably orienting surface disturbances on the forward portion of the cylinder.