Vortex shedding from two circular cylinders of equal diameter in a staggered configuration was studied experimentally in the subcritical Reynolds number regime, for Re = 3.2×104–7.4×104. The dimensionless centre-to-centre pitch ratio of the staggered cylinders was ranged from P/D = 1.125–4.0, and the incidence angle was varied in small increments from α = 0°–90°. The behaviour of the Strouhal number measurements was broadly classified according to whether the cylinders were closely, moderately, or widely spaced, corresponding to P/D < 1.5, 1.5 ≤ P/D ≤ 2.5, and P/D > 2.5, respectively. For closely spaced staggered configurations, the flow around the cylinders is similar to a single bluff body, and only a single Strouhal number is measured. For moderately spaced cylinders, two distinct Strouhal numbers are measured when α > 30°, but there is considerable scatter in the Strouhal data when α < 30°. For widely spaced cylinders, the Strouhal numbers remain close to that of a single circular cylinder, in contrast to the behaviour of the aerodynamic forces. Evidence of the outer lift peak is seen in the power spectra for the downstream cylinder.

This content is only available via PDF.
You do not currently have access to this content.