Technical note: Minimal conditions for venturi aeration of water flows

Abstract

Air vacuum processes with venturi, simple in design and easy to operate, have been used in a wide variety of industrial and water/waste water treatment applications in environmental engineering. The air vacuum process occurs when a minimal amount of differential pressure exists between the inlet and outlet regions of a venturi device. This paper introduces an air vacuum process within a venturi device and its relationship with the Reynolds number. In this case study, air vacuum characteristics such as volumetric air flowrate were studied, depending on water flowrate. An empirical correlation for air vacuum with a venturi device is presented to predict the volumetric air flowrate (Qa) as a function of water flowrate (Qw), diameter of throat (d2), diameter of air vent or suction port (dh) and Reynolds number (Re). A minimal Reynolds number for absorption of air is observed in the transition flow region for the inlet of a venturi device (Re ≥ 1900) and in the turbulent flow region for the throat of a venturi (Re ≥ 3900).