Flow-Field Prediction in Submerged and Confined Jet Impingement Using the Reynolds Stress Model

The flow field of a normally impinging, axisymmetric, confined and submerged liquid jet is predicted using the Reynolds Stress Model in the commercial finite-volume code FLUENT. The results are compared with experimental measurements and flow visualizations 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. Results are presented for nozzle diameters of 3.18 and 6.35 mm, at jet Reynolds numbers in the range of 2000 to 23,000, and nozzle-to-target plate spacings of 2, 3, and 4 jet diameters. Up to three interacting vortical structures are predicted 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. The computed flow patterns were found to be in very good qualitative agreement with experiments. The radial location of the center of the primary toroid was predicted to within ±40 percent and ±3 percent of the experimental position for Re = 2000–4000 and Re = 8500–23000, respectively. The magnitude of the centerline velocity of the jet after the nozzle exit was computed with an average error of 6 percent. Reasons for the differences between the numerical predictions at Re = 2000–4000 and experiments are discussed. Predictions of the flow field using the standard high-Reynolds number k-ε and renormalization group theory (RNG) k-ε models are shown to be inferior to Reynolds stress model predictions.