Characteristics of Turbulent Wakes Generated by Twin Parallel Cylinders

Abstract

This research aims to study the characteristics of the wake generated by twin cylinders. The cylinders are arranged in parallel side-by-side and staggered arrangements. The mainstream velocity is varied between 18 m/s and 20 m/s, which are equivalent to cylinder Reynolds numbers between 4750 and 5300. The cross-stream spacing ratios are 2, 3, 4, and 6 times the cylinder's diameter for the side-by-side arrangements. For the staggered arrangement, the cross-stream and streamwise spacing were varied between 2 and 4 times the cylinder diameter. The results show that the spacing ratio s/d has a significant effect on the wake development and interactions. The wakes of the side-by-side cylinders tend to merge into a single wake for cross-stream spacing of 2d and 3d at early stations, equivalent to 15 and 30 times the cylinder diameter, respectively, and merge completely at 50 and 100 times the cylinder diameter for 4d and 6d, respectively. Velocity measurements are used to develop a correlation that relates the wake merging distance to the cylinder spacing. Turbulence measurements are used to develop a correlation between the turbulence intensity and the streamwise distance. The comprehensive survey of the results and the correlations developed are provided in order to facilitate numerical model development and evaluation.