IMPACT OF VARYING THROAT DIAMETER IN THE VENTURI SYSTEM ON THE AERATION EFFICIENCY

Abstract

Venturi tube is an applicable and economic alternative device to transfer gas-liquid. It is simply designed easily manufactured and it does not need maintenance. The process of air vacuum through venturi tube has been used widely in many agricultural, industrial and the process of water purification (e.g. chlorine and ozone injecting for drinking water, injecting chemicals as liquid fertilizers in the system of sprinkler irrigation/ transferring dissolved oxygen in drinking water and waste water treatment). The main objective of this research is to evaluate effect of geometric characteristics on the aeration efficiency in the venturi system. To achieve this goal, the venturi is designed and carried out, from transparent polycarbonate. Experiments were conducted on clear-water conditions at different discharges (Qwater): 44.16, 58.88, 73.59 and 88.31 lit/min which correspond to four inlet velocities (v): 1.5, 2.0, 2.5 and 3.0 m/s. The study involved selecting three different throat diameters (dt): 10, 12.50 and 15 mm, and three different air inlets orifices diameters (ds): 3, 5 and 8 mm. Five different outlets angles have been used (β): 7 o , 10 o , 15 o , 21 o , and 25 o with inlet angle (α) stabilization at 7 o. The inlet and the outlet diameter (D) and throat length (Lt) in all the experiments were constants and equals to 25 and 8 mm, respectively. The results of the study demonstrated that the throat diameter of the venturi tube affects the aeration efficiency.The best results were given for the relationship between (Qair / Qwater) = 92% with outlet angle of 25 o in the case of (dt ̸ D = 0.4 and ds ̸ D = 0.32 and Lt ̸ D = 0.32). Additionally, empirical equations were gotten for venturi tubes linking air flow and water flow to throat lengths and diameters, venturi outlets angles. air inlets orifices diameters and Reynolds numbers.