Experimental Study on Flows around Two Rotating Circular Cylinders in Side-by-Side Arrangement at Moderate Reynolds Number

The flow characteristics of two rotating side-by-side circular cylinders are investigated experimentally with particle image velocimetry (PIV) and Hot-wire anemometer in this paper. The Reynolds number, Re, is 950 and the non-dimensional center distances, T/D, are 1.11 and 1.6, respectively, where T and D are the center distance between the two cylinders and the cylinder diameter. The velocity ratio, vertical bar alpha vertical bar, ranges from 0 to 2, where vertical bar alpha vertical bar is the circumferential speed at the cylinder surface normalized by the free stream velocity. Three rotational directions are analyzed. The experimental results show that the first rotation is optimal for weakening the near-wake vorticities. Both the vorticities and turbulence diminish significantly and the time-averaged velocity field is homogenized with increasing vertical bar alpha vertical bar. The second rotation enlarges the vorticity distribution. Under the third type of rotational direction the time-averaged velocity loss deflects from the free stream with the increase of vertical bar alpha vertical bar. Meanwhile, the wake vorticity and turbulence with turbulivity higher than 20% both shift downwards, with the intensity of turbulence and vorticity unchanged.