Near-Wakes of Elliptic Cylinders in Subcritical Flow

The near-wake aerodynamics of a set of two-dimension al, stationary, elliptic cylinders is studied experimentally during the organized wake condition (Reynolds number = 68,000) as a function of the cylinder eccentricity and angle of attack, An extensive scanning of the pressure field provides useful information concerning the vortex formation region, longitudinal and lateral spacings between the vortices, the classical wake geometry ratio, and the vortex velocity. A flow visualization study through the Schlieren technique in conjunction with high-speed photography gives preliminary information about location of the separating shear layers, their oscillations, and position of the first vortex. The rise and decay of the unsteady pressure in the vortex formation region appears to substantiate the visual observation concerning the first vortex. = mean static pressure coefficient, (p-p^0 = ratio of the maximum fluctuating pressure (average amplitude) at a transverse station in the wake to the corresponding value on the surface of the model for a given angle of attack, PH/(Pm)max = longitudinal spacing between vortices = Reynolds number, V.^2a/v — Strouhal number based on the projected height of the model, Nomenclature CDh = mean drag coefficient based on the projected height, pressure