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

Abstract

One of the circular cylinders with several diameters was elastically suspended with springs in the jet impingement region between a jet slot and a heat transfer target plate. The slot-to-plate distance H was kept constant to be 3 or 5 times of the slot width, h = 15 mm. The Reynolds number was fixed at 10 000, being exceptionally 5 000 in the case of flow visualization. Periodical swinging motion of the cylinder across the jet was observed because of the cylinder vibration self-induced with the jet flow. It was found that this vibration has direct effects on the characteristics of the flow and heat transfer around the stagnation region. The ensemble-averaged values of velocity and its fluctuation depend on the cylinder diameter and the impinging distance. The local Nusselt number in the case of H/h =3 with the vibrating cylinder of the smallest diameter D=4 mm was increased up to 1.15 times of the Nusselt number without the cylinder. The interesting patterns of Interm Ittency function defined together with threshold levels of turbulence intensity were observed in the above case.