Karman Vortex Effect on the Aerodynamic Forces to Rectangular Cylinders

<jats:p>Standing on the back-ground associated with the complicated bluff body aerodynamics affected by Karman vortex, the fundamental wind tunnel tests have been carried out to clarify the role of Karman vortex on the aerostatic forces and the aerodynamic forces of 2D rectangular cylinders with various side ratios in the range from B/D=0.3 to B/D=15. For mitigation of Karman vortex, a splitter plate with suitable size was installed in a wake center. As far as stationary drag force, the sharp peak in CD-B/D diagrams, completely disappear by a splitter plate installation. On the other hand, the value of dCL/dα is significantly sensitive to the Karman vortex, in particular, even its sign changes in the range from B/D=0.6 to B/D=0.7 and B/D=3.0 to B/D=4.0, which means the significant role of the Karman vortex on the galloping instability, from the point of quasi-steady theory. Furthermore, the flutter derivatives are also drastically affected by Karman vortex in the rather wide reduced velocity far from the Karman vortex resonant reduced velocity. In summary, it would be emphasized that the substantial bluff body flow might be characterized by the side ratio of cylinders, and these fundamental flows should be significantly or slightly affected by Karman vortex depending on their side ratios of cylinders.</jats:p>