Influence of geometry on the galloping instability of rectangular cylinders in the Reynolds number range 1,000–10,000

Abstract

Wind tunnel experiments were used to investigate the effects of geometry on the transverse galloping behavior of nominally rectangular cylinders at Reynolds numbers from 1,000 to 10,000. Static measurements of the lift and the drag forces were used to determine the variation of the normal force coefficient with angle-of-attack, in accordance with the typical quasi-steady description of galloping. Cylinders with unity chord-to-thickness ratio (side ratio) were found to vary from unstable, to neutrally stable, to stable as the corner radius was increased from sharp, to half-round, to fully-round, with this effect diminishing with decreasing Reynolds number. Cylinders with side ratios of 2 or 3 demonstrated either stability over the entire Reynolds number range, or a transition from unstable to stable with increasing Reynolds number, depending on corner radius. The results demonstrated that in general, increasing the corner radius had a stabilizing effect.