Properties of Karman Vortex and Motion-induced Aerodynamic Forces on Rectangular Cylinders with Side Ratios of 1 and 2

Abstract

In this study, unsteady aerodynamic lift forces of rectangular cylinders of side ratio B/D=1 and 2 were measured under the forced vibration condition, and the relation between the Karman vortex and galloping are discussed. As a result, for the B/D=1 section, the Karman vortex-induced vibration and galloping must occur continuously and the onset velocity of galloping should be 1/St. But the conventional Karman vortex-induced vibration may occur only at very small vibration amplitude region. On the other hand, for the B/D=2 section, it seems that the conventional Karman vortex-induced vibration never occurs and the onset velocity of galloping is higher than 1/St. And also, the onset of galloping seems to be related to certain vortex effects, and then further investigations must be needed.