Mean aerodynamic forces acting on a pair of circular cylinders in cross-flow

Abstract

Two circular cylinders of equal diameter in a staggered configuration, with a centre-to-centre pitch ratio of PID = 2.0, were tested in the subcritical Reynolds number regime. The incidence angle of the cylinder configuration was varied from a = 0° to 90° and the aerodynamic forces were measured on both the upstream and downstream cylinders. The forces acting upon the upstream cylinder did not show significant variation with the incidence angle despite the marked changes in the vortex shedding behaviour associated with this cylinder. The aerodynamic forces on the downstream cylinder were sensitive to the tendency towards shear layer reattachment at small incidence angles. The inner lift peak for the downstream cylinder, at a = 9°, was attributed to the loss of shear layer reattachment observed at lower incidence angles, while the minimum drag force experienced by the downstream cylinder occurred under shear layer reattachment conditions. Within the range of Reynolds number examined, no apparent Reynolds number effects were noticed.