Abstract
The specific aim of this work is to develop a new technique to control vortex excitations of a circular cylinder by utilizing interference of a downstream strip-plate in cruciform arrangement. In the previous paper, it is show that two longitudinal vortices, trailing vortex and necklace vortex, shed near the crossing of a fixed circular cylinder/strip-plate system. In this paper, influence of the strip-plate on vortex excitation was investigated by wind tunnel experiment. The strip-plate suppresses Karman vortex excitation effectively compared with a downstream circular cylinder. A wider strip-plate has a larger suppression effect. The trailing vortex induces vortex excitation when gap-to-diameter ratio s/d less than 0.3. When the strip-plate width equals to the upstream circular cylinder diameter, the velocity range for longitudinal vortex excitation is 5 times wider than the case of the downstream circular cylinder. Longitudinal vortex excitation by downstream strip-plate occurs over a wide velocity range, and it can be easily controlled by s/d adjusting.
