Flow field and heat transfer of a two-dimensional impinging jet disturbed by an elastically suspended circular cylinder

The flow field around a circular cylinder elastically suspended with a cantilever-type plate spring in the jet impingement region was visualized to investigate the mechanism of the impingement heat transfer. The impingement distance H was kept constant at 3 or 5 times as large as the jet slot width, h = 15 mm.The Reynolds number was fixed at 10,000, or 5000 in the case of flow visualization. The self-induced periodic swing motion of the cylinder across the jet axis was caused by the interaction between the jet and the elastically suspended cylinder. It was found that this swing motion has direct effects on the flow and heat transfer characteristics of the stagnation region. The ensemble-averaged values of the flow velocity and its fluctuations depended on the cylinder diameter and the impingement distance. The local Nusselt number in the case of H/h = 3 with the oscillating cylinder of the smallest diameter D = 4 mm was increased to 1.15 times as large as that without the cylinder. The interesting patterns of the intermittency function defined with a certain threshold level of turbulence intensity were obtained under the above experimental conditions. © 2001 Scripta Technica, Heat Trans Asian Res, 30(4): 313–330, 2001