Finite Aspect Ratio Effects on Vortex Shedding Behind Two Cylinders at Angles of Incidence

Wind tunnel tests were undertaken at subcritical Reynolds numbers to determine the vortex shedding characteristics behind a pair of finite circular cylinders at distances from one to six diameters apart and at all angles to one another. In addition, individual finite cylinders with aspect ratios 0.67 ≤ L/D ≤ 11.33 were examined to determine the effect of aspect ratio on shedding frequency, and to measure the frequency of the tip vortex when it is present. Aspect ratio was found to be a significant factor in the difference between shedding frequencies of the two cylinders at oblique angles. It was also found that “lock-on” of the two frequencies occurred when longer aspect ratio cylinders were upstream of shorter ones, but not in the reverse case.