The role of cross‐sectional geometry of high‐head gated conduit in oxygen transfer efficiency

Abstract

The concentration of dissolved oxygen is an important indicator of water quality because aquatic life lives on the dissolved oxygen in the water. This can be achieved by using hydraulic structures because of substantial air bubble entrainment at these structures. Closed conduit aeration is a particular instance of this. In the present study, experiments were carried out to investigate the role of cross‐sectional geometry of high‐head gated conduit in oxygen transfer efficiency. In the first part of this study, the role of cross‐sectional geometry of high‐head gated conduit in air‐demand ratio was investigated. In the second part, the role of cross‐sectional geometry of high‐head gated conduit in oxygen transfer efficiency was investigated. Results pointed that the cross‐sectional geometry of the high‐head gated conduit had an important effect on the air‐demand ratio and the oxygen transfer efficiency. Moreover, a design formula was obtained for the conduit having the highest oxygen transfer efficiency relating the oxygen transfer efficiency to air‐demand ratio, Froude number, gate opening, conduit length and gate opening ratio. There was good agreement between the measured and the predicted values. The obtained results will be useful in future modelling processes and aid the practicing engineer in predicting oxygen transfer efficiency of high‐head gated conduits.

Role of Gate Type in the Air-Demand Ratio in Closed Conduits

“…Previous studies have shown that injecting air into the flow downstream of the gate can significantly reduce the risk of cavitation damage. The air-demand ratio and the aeration efficiency in gated closed conduits have been investigated by Aydin et al (2021Aydin et al ( , 2022Aydin et al ( , 2023, Baylar and Batan (2010), Baylar et al ( , 2021Baylar et al ( , 2022, Campbell and Guyton (1953), Haindl and Sotornik (1957), Hohermuth (2017Hohermuth ( , 2019, Hohermuth et al (2020), Kalinske and Robertson (1943), Mortensen (2009), Mortensen et al (2011Mortensen et al ( , 2012, Mortensen and Kubitschek (2016), Oveson (2008), Ozkan et al (2006aOzkan et al ( , 2006bOzkan et al ( , 2010Ozkan et al ( , 2014Ozkan et al ( , 2015, Rajaratnam (1962), Safavi et al (2008), Sharma (1976), Speerli (1999), Speerli and Hager (2000), Tuna et al (2014), Unsal et al (2008Unsal et al ( , 2009Unsal et al ( , 2014, USACE (1964), Wisner (1965).…”

“…The results showed that the cross-sectional geometry of the conduit had an important effect on the air-demand ratio, especially at low gate opening rates, and the design equations for estimating the air-demand ratio were presented. Baylar et al (2022) indicated that the cross-sectional geometry of the conduit plays an important role in oxygen transfer efficiency.…”