The effect of length of free-surface gated circular conduit on air-demand ratio and aeration efficiency

Abstract

Aeration is the process of bringing water and air into close contact in order to increase dissolved oxygen concentration. The concentration of dissolved oxygen is an important indicator of water quality because aquatic life lives on the dissolved oxygen in the water. The hydraulic structures can be accepted as the key components in increasing dissolved oxygen concentration because of the strong turbulent mixing associated with substantial air bubble entrainment at these structures. Closed conduit is a classic example of a hydraulic structure where aeration occurs. This work focused on determining the effect of conduit length on air-demand ratio and aeration efficiency in free-surface gated circular conduits. Experimental results showed that the Froude number had an important effect on the air-demand ratio and the aeration efficiency. The effect of the conduit length on the air-demand ratio and the aeration efficiency changed depending on the Froude number. It was demonstrated from the results that a free-surface gated circular conduit flow system had high efficiency in transferring oxygen from air bubbles to water. Moreover, a formula for the aeration efficiency was presented relating the aeration efficiency to the conduit length and the Froude number.

Influence of square jets in Oxygen transfer in an Open Channel

“…The impact of the Froude number on oxygen transport was examined by Aydin [26], which is an important metric in hydraulic engineering. The results from this study (as shown in figure 6) are consistent with prior research [27][28][29][30][31] in demonstrating that this dimensionless parameter has a significant influence on oxygen transfer.…”

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

“…Experimental studies on air‐demand ratio and the oxygen transfer efficiency in closed conduits were carried out by investigators (e.g. Campbell & Guyton, 1953; Escarameia, 2007; Haindl & Sotornik, 1957; Kalinske & Robertson, 1943; Mahmoudi‐Rad & Najafzadeh, 2021; Mortensen, 2009; Mortensen et al, 2011, 2012; Oveson, 2008; Ozkan et al, 2006, 2014, 2015; Rajaratnam, 1962; Shamsaei & Soleymanzadeh, 2006; Sharma, 1976; Speerli, 1999; Speerli & Hager, 2000; Speerli & Volkart, 1997; Stahl & Hager, 1999; Tuna et al, 2014; Unsal et al, 2008, 2009; USACE, 1964; Wisner, 1965). The comprehensive literature search did not identify any published analytical or physical studies investigating the role of cross‐sectional geometry of high‐head gated conduit in oxygen transfer efficiency.…”