Air entrainment by impinging jets. Experimental identification of the key phenomena and approaches for their modelling.

The gas entrainment by impinging water jets is studied by the means of experiments and CFD simulations. In the experiments, the nozzle height above the water pool and the water velocity inside the nozzle is varied and the bubble entrainment below the jet is observed with a video camera. Quantitative data for bubble sizes and the geometry of the bubble plume are obtained by image processing. The development of two phase jets under water is also studied with CFD, using the Euler-Eulerian approach. Defining a criterion for an average penetration depth, the simulated plumes are compared with those observed in the experiments