Abstract:

The amount of dissolved oxygen (DO) in the river is a major parameter that indicates the quality of the water and the survival of aquatic organisms. Short contact of hydraulic structures with rivers has significant effects on dissolved oxygen content. The cascades and venturies are important hydraulic structures used in the aeration of water. In venturi systems, negative pressure occurs in the throat section by means of the sudden increase of the velocity of the water in the narrowing section. The air enters into the system because of this low pressure caused by the velocity changes. The amount of air entering in the system varies depending on the ratio between the venturi inlet and throat sections. In this study, circular venturi diameters of 36, 42 and 54 mm having different hole configuration were used. The diameter of throat regions was determined as 0.5 and 0.75 times the diameter of the venturi and the length of the throat region was equal to and 2 times the diameter of the throat region. On the venturi, 3 pairs of holes were drilled 6 mm in diameter with a distance of 0.75 times the length of the throat region starting from the midpoint of the throat region. The installation of the venturi with the system carried out and the effects on the dissolved oxygen concentration in the water were investigated. The results obtained from the experiments were compared and interpreted with graphs. In the study, it was observed that while venturi diameters increased, DO values decreased. In addition, it was observed that the increase in the length of the venturi throat region also increased the DO values.

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