Performance analysis of plunging jets having different geometries

Despite numerous works reporting the oxygen transfer by circular plunging jets, few studies have been carried out on plunging jets of different geometries, namely circular, square, rectangular and rectangular with rounded edge. The experimental study on these four geometries has revealed that jet geometry/shape has significant effect on the penetration depth and overall volumetric oxygen transfer coefficient of plunging jets. It has been observed that conventional circular plunging jets have highest penetration depth, but the overall volumetric oxygen transfer coefficient of rectangular with rounded edge plunging jets has been significantly higher (1.45 times) than circular plunging jet for same flow area and other similar conditions. This is due to the optimal and balanced utilization of incipient kinetic jet power by rectangular with rounded edge geometry, and hence suggests their distinct advantage over other geometries. Empirical relationships have also been proposed to estimate the penetration depth and overall volumetric oxygen transfer coefficient from kinetic jet power for different geometries of plunging jets. The suggested empirical relationships can be useful in deciding the depth of aeration tank, determining the optimum geometry/configuration and comparing the performance or oxygen mass transfer rates of different geometries and configurations of plunging jets under similar flow conditions.