Vortex Wake from Tapered and Stepped Circular Cylinders in a Uniform Flow.

Abstract

This paper presents an experimental study on the flow around tapered and stepped circular cylinders and the structure of the shedding vortices. The surface pressure distributions on the cylinder and the spectra of the wakes were measured for them. The main results are as follows. (1) In the case of the tapered circular cylinder, the shedding vortices are connected within some spanwise width. The break points of the cell appear in a spanwise surface pressure distribution before the separation point. (2) In the case of the stepped circular cylinder, the Strouhal number is larger than that of the straight circular cylinder in the region where the pressure balances spanwise in the wake. (3) In the case of the stepped circular cylinder, the shedding vortices from small and big cylinders are connected with each other for a diameter ratio of more than 0.64 and are broken for a diameter ratio of less than 0.56.