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Flow in Open Channels
Published in William S. Janna, Introduction to Fluid Mechanics, Sixth Edition, 2020
A sluice gate is a vertical gate used in spillways to retain the flow. A sketch of a partially raised gate is shown in Figure 7.4. For frictionless flow under a partially raised gate in a rectangular channel, we can write the following equations: Continuity:Q=AV=bz1V1=bz2V2Energy:p1ρg+V122g+z1=p2ρg+V222g+z2
Gates and valves
Published in Geraldo Magela Pereira, Spillway Design – Step by Step, 2020
There are several types of gates: sluice, hinged, cylindrical, stoplog, caterpillar, miter, rolling, segment, sector, Stoney, drum, roof and fixed roller gate. In Brazil, these types are defined in Brazilian Standard – Hydraulic Gates – Terminology, NBR 7259 (1982), as well as in the book Design of Hydraulic Gates (Erbisti, 2004). Some of them are shown in the illustrations in this book (Figures 9.1 to 9.4).
Open Channel Flow
Published in Ahlam I. Shalaby, Fluid Mechanics for Civil and Environmental Engineers, 2018
The sluice gate for open channel flow is analogous to the orifice flow meter for pipe flow. In particular, one may consider the sluice gate a special case of orifice flow. One may recall that for an orifice meter (see Figure 9.36a), a jet contraction occurs on both sides of the jet, and the pressure distribution in the vena contracta is not hydrostatic (it is dynamic), whereas for a sluice gate, as illustrated in Figure 9.36b, the jet contraction (vena contracta) occurs only on the top of the jet, and the pressure distribution in the vena contracta is hydrostatic (because y1 is large compared to y2). A sluice gate is a vertical, sharp-edged flat plate, which extends over the full width of the channel that is inserted in an open channel and is used to regulate and measure the flowrate in open channel flow. The flowrate, Q is a function of the upstream depth, y1; the downstream depth, y2; the gate opening or depth of flow at the gate, a; and the channel width, b. When the sluice gate is opened, the upstream subcritical flow at point 1 accelerates as it approaches the sluice gate (which is a control), reaching critical flow at the gate, and then accelerates further to supercritical flow downstream of the gate at point 2. One may note that the acceleration of the flow is due to the steady decline in the elevation of the free surface from point 1 to point 2; thus, the conversion of the elevation head at point 1 into a velocity head at point 2. It is interesting to note that the sluice gate serves as a “control,” at which the critical depth of flow, yc occurs, assuming ideal flow (thus, ideally, a = yc). However, due to the sharp edge of the sluice gate, the fluid viscosity causes a contraction in the depth of flow both at the control and downstream of the control at point 2. Therefore, the contraction of flow causes (1) the critical depth of flow, yc to occur just upstream of the sluice gate, and (2) the supercritical depth of flow at point 2, y2 to be less than the gate opening or depth of flow at the gate, a by an unknown amount, as modeled by a contraction coefficient, Cc = Aa/Ai = y2a/a. Finally, one may note that due to the contraction of flow at the sluice gate, this ideal flow meter is not considered to be a critical depth meter; thus, the discharge coefficient, Cd is a function of both a velocity coefficient, and a contraction coefficient, where Cd = CvCc.
Numerical analysis of triangular labyrinth side weir in triangular channel
Published in ISH Journal of Hydraulic Engineering, 2022
For validation of CFD results, experimental set up is used which is consisting of 4 m long triangular channel having 0.4 m depth. The triangular shape of the main channel is obtained by inserting a triangular metal plate in the rectangular channel. The main channel is provided with 0.4 m side opening where steel plate fabricated painted triangular labyrinth side weirs with variation in included angle can be fitted. The sluice gate is provided at downstream of the main channel to control depth of water in the channel. Water is supplied in the channel from the sump by a pipe connected to a pump with valve arrangements to vary discharge in the main channel. At the inlet of the main channel and outlet of collecting channel calibrated 90° V notch is provided to measure the discharge. The few numerical results are validated for 45°, 60° and 90° triangular labyrinth side weir. The flow over labyrinth side weir on the experimental setup is as shown in Figure 3.
A topology-alterative two-phase flow solver and its validation for a dynamic hydraulic discharge process
Published in Journal of Hydraulic Research, 2019
Hydraulic sluice gates have been widely used in water conservancy projects for many years. With designed opening motions, plain and radial gates, which are the most common types of sluice gates in this specialized area, enable hydraulic engineers to control water flow to meet various requirements, such as flood regulation (Chiang & Willems, 2015), hydroelectric generation (Li, Masuda, & Nagai, 2016), agricultural irrigation (Bouisse, Baume, & Gassama, 2011) and inland navigation (Zhang, Zhang, Wu, & Yi, 2016). To improve the management of water flow, it is important for designers and engineers to understand the relationship between flow variations and gate opening motions. A series of useful formulas were developed to predict flow discharge after decades of research (Chen et al., 2010; Zahedani, Keshavarzi, Javan, & Shahrokhnia, 2012). Some of these formulas are based on instructional or mandatory standards, which provide guidelines for substantial model experiments (Aydin, Telci, & Dundar, 2006; Wang et al., 2002) and engineering practices (Carvalho & Leandro, 2012; Ramos & Almeida, 2001). However, the above-mentioned formulas are typically derived and regressed under the priori condition of a fixed rate of gate opening and a steady state assumption; therefore, the hydrodynamic behaviour of water flow due to gate movement is not considered in the predictions.