Galloping instability and flow field of rectangular cylinder with side openings

Abstract

This research investigated the relationship between the size of side openings and the aerodynamic performance. To simplify the discussion, the rectangular cylinder with a side ratio of 2 was applied. For the different opening area ratio (OR), the aerodynamic performance was monitored through vertical one degree of freedom (1DOF) free vibration tests, forced vibration test and aerodynamic force test. To further investigate characteristics of the flow field around the model, time-averaged streamline was calculated through flow visualization experiments and PIV analysis. With the increase of OR, the critical wind velocity gradually increased. Meanwhile, the aerodynamic damping increased with the increase of OR from 0 to 0.75 and then decrease with OR. It can be explained by that the shear layer approached the trailing edge of the model with the increase of OR and finally reattached on the side surface from OR = 0.875.