Acoustic testing of the vortex structure produced by an air flow about an array of cylinders

Results of experiments on the scattering of a plane ultrasonic wave from a vortex wake formed in an air flow behind a lattice of vertical cylinders are presented. The lattice is periodic in the direction perpendicular to the oncoming flow. The experiments are performed in a wind tunnel for two values of the Reynolds number, namely, Re = 75 and 500, and for lattices with different numbers of cylinders and with different lattice periods g = (2.5–15)d (where d is the diameter of the cylinders). The measured parameters of the scattered waves are used to estimate the degree of transverse correlation between the vortex wakes formed behind the cylinders for flows with different Reynolds numbers. The results obtained from an analysis of the characteristics of the scattered sound are compared with the results of direct hot-wire anemometer measurements and with the data obtained by other researchers.