Turbulent uniform flow around cylinders of finite length

Experimental results are presented which demonstrate the effects of the free end of a circular cylinder on the mean and fluctuating pressures, mean drag force, and the phenomenon of vortex shedding when the cylinder was exposed to uniform flow. The work was carried out at Reynolds number of 0.7 x 105, and turbulence level of 0.9%. The results of the pressure measurements indicated the presence of a suppressed two-dimensional region on the lower part of the cylinder. The functional relationship between the absolute maximum fluctuating pressure coefficient and cylinder length/diameter ratio was obtained. The accuracy of the drag measurements was checked by integrating the pressure profiles, and excellent agreement between the integrated pressure data and the direct measurement was obtained. The vortex shedding measurements suggested the possible existence of three distinct sets of vortex rows with different frequencies. In the lower region, vortex loops were shed with a frequency such that it yielded a Strouhal number appropriate to an infinitely long cylinder.