The occurrence of the free surface vortex is inherent to numerous physical situations and may result in the entrainment of air which is detrimental for many engineering processes and devices. The present study experimentally elucidates the vortex formation and subsequent air entrainment patterns for pump intake-induced vortices. The vortex profiles are distinctly categorized based on their specific behaviours for high (H/d > 2.6) and low (H/d {less than or equal to} 2.6) submergence ratios. Regime maps are presented for high submergence water levels by the amalgamation of visual inspection of interface profile inside the tank and withinthe flow intakes. The entrained air entities have transformed from discrete bubbles to a continuous gaseous core by passing through the number of intermediate fluidic structures within the pipe upon the increase of flow rate in the entrainment regime. The flow rate at the inception of air entrainment has increased with an increase in height of the nominal free surface. The transient evolution of the vortex tip depicted different rates of its downward traversal depending upon the location of occurrence between the free surface and flow inlet. The use of an air separator system has resulted in the mitigation of the flowfluctuations in the entrainment regime.

No abstract