Investigation of the geometry effect on air-demand ratio in conduits with a sluice gate

Abstract

Gated conduits involve high-velocity air-water flow. When the studies on the gated conduits are examined, it is determined that the air-demand ratio changed according to the hydraulic and geometric parameters. However, no study has investigated the effect of the cross-sectional geometry of high-head conduits with a sluice gate on the air-demand ratio. In this study, the effect of conduit cross-sectional geometry on the air-demand ratio is examined. Results indicate that conduit cross-sectional geometry is an important effect on the air-demand ratio, especially at 10% and 15% gate opening rates. It is seen that the effect of the conduit geometry on the air-demand ratio decreases at 20%, and greater gate opening rates. Moreover, a formula for the air-demand ratio is presented relating the air-demand ratio to the gate opening rate, Froude number, hydraulic radius, and conduit length was presented for estimating the air-demand ratio.

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

“…Sluice and radial gates are common devices used to control flow in closed conduits (Figure 2). Aydin et al (2021Aydin et al ( , 2023 investigated the effects of cross-sectional geometry, gate opening rate, conduit length, and flow rate on the air-demand ratio in the high-head conduits with a radial gate and a sluice gate (Figure 3). The experimental setup was constructed at the Hydraulic Laboratory of Firat University, Elazig, Turkey, and the components used are shown in Figure 4.…”

“…The aim of this study is to investigate the effect of gate type on the air-demand ratio in high-head conduits. For this purpose, the air-demand ratios of two different gate types, radial gate, and sluice gate, were compared with each other using the experimental results of Aydin et al (2021Aydin et al ( , 2023. A total of 1008 experimental results were considered, 336 for the 60×100 rectangular cross-sectional conduit, 336 for the 100×60 rectangular cross-sectional conduit, and 336 for the circular conduit.…”

“…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).…”

“…Hohermuth et al (2020) showed that demand increases with increasing the Froude number at the vena contracta, increasing relative vent size, increasing relative tunnel length, and decreasing vent loss coefficient and tunnel slope. Aydin et al (2021Aydin et al ( , 2023 investigated the effect of conduit cross-sectional geometry on the air-demand ratio in high-head conduits with a radial gate and a sluice gate. 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.…”