Abstract
An attempt has been made to measure the mean residence time of the gas entrained by a plunging water jet. The mean residence time, in the high jet velocity region on the gas entrainment curve, does not depend on jet velocity and tends to remain approximately constant for each set of experimental conditions. The experimental data are correlated with both the ratio (Lj/D) of jet length (Lj, ) to nozzle inside diameter (D) and the angle (α) between the water jet discharge and the bath surface.
The gas holdup (H) is evaluated by multiplying the gas entrainment rate by the mean residence time of the entrained gas. From the evaluation of the gas holdup the following two relationships can be established for region IV depending upon the Lj/D ratio:
Lj/D≤70: H=8.07 × 10-5(ρ1D2V2)(Lj/D)0.35 sin0.2α
Lj/D>70: H=1.86 × 10-4(ρ1D2V2)(Lj/D)0.15sin0.3α
where V is the water jet velocity and ρ1 is the density of the liquid.
