Experimental study of entrained air-core structures induced by a pump intake vortex

Abstract

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 behaviors for high (H/d > 2.6) and low (H/d [Formula: see text] 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 within the 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 in the flow rate in the entrainment regime. The flow rate at the inception of air entrainment has increased with an increase in the 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 flow fluctuations in the entrainment regime.