Flow induced vibration (FIV) of a pentagonal cylinder with high mass-damping ratio

In this study, fluid structure interactions of a fixed and oscillating pentagonal cylinder are studied using experimental approaches. Specifically, flow induced vibration (FIV) of a pentagonal cylinder is studied with six different incidence angles (𝛼) in a recirculating wind tunnel at fixed mass damping ratios. A series of free oscillation experiments are carried out in order to explore galloping behaviour as well as the lock-in region for vortex induced vibration (VIV). It is found that VIV for a pentagonal cylinder is substantially stronger than for a circular cylinder with a similar mass ratio. VIV maximum amplitude changes non-monotonically with incidence angle, and is smaller for incidences where galloping is dominant. Also, galloping was found to be substantially stronger where the stiffness of the system is lower.