Visualization of the flow field in a conined and subemrted impinging jet

摘要

The flow field of a normally impining, axisymmetric, confined and submerged liquid jet is studied using flow visualization. The results are compared with computations and experimental measurements of the flow field, and are used to describe the position of the recirculating toroid in the outflow region which is characteristic of the confined flow, field. Changes in the features of the recirculation pattern due to changes in Reynolds number, nozzle diameter and nozzle-to-target plate spacing are documented. Reuslts are presented for nozzle diameters of 3.18, 6.35, and 12.7 mm, at jet Reynolds numbers in the range of 2000 to 23000, and nozzle-to-target plate spacing of 1, 2, 3, and 4 jet diameters. Up to three interacting vortical sturcturs are observed in the confinement region at the smaller Reynolds numbers. The center of the primary recirculation pattern moves away from the centerline of the jet with an increase in Reynolds number, nozzle diameter, and nozzle-to-target plate spacing. As the recirculating toroid moves away from the jet axis, more of the ambient fluid is entrained into the confinement region.