Hybrid scale-resolving simulation of flow field and mixing performance in a water jet pump

This study employs the Stress-Blended Eddy Simulation (SBES) model to analyze the internal flow and mixing behavior of a jet pump. The model is validated against experimental data for two cases: a confined jet and a water jet pump. The average relative errors between the present SBES model predictions and the experimental data for the axial distributions of the mean and fluctuating streamwise velocities in the confined jet are 3.73% and 14.74%, respectively. Increasing the flow ratio of the jet pump to 2.16 delays vortex breakdown, while lower ratios (0.5) cause earlier destabilization and a shorter laminar region. Nozzle retraction shifts the jet breakup upstream without affecting the maximum turbulence intensity. The effects of a diverging nozzle with an 20° exit angle (D20) on the mixing performance of the jet pump is compared against a straight nozzle (D0). In the mixing throat, both the radial velocity and the streamwise vorticity of the D20 configuration are one order of magnitude higher than those of D0, thereby shortening the mixing length by 66% and reducing the scalar concentration variance by 81.9%. A comparison of the present SBES results with those obtained using Large Eddy Simulations reveals that the SBES model outperforms the dynamic Smagorinsky model in predicting the confined jet flow field and provides results comparable to those of the dynamic mixed subgrid-scale model. This study demonstrates the capability of SBES as an effective tool for high-fidelity jet-pump analysis by resolving unsteady vortex structures inaccessible to Reynolds-averaged Navier–Stokes models.