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Spillway chute
Published in Willi H. Hager, Anton J. Schleiss, Robert M. Boes, Michael Pfister, Hydraulic Engineering of Dams, 2020
Willi H. Hager, Anton J. Schleiss, Robert M. Boes, Michael Pfister
The implications of roll waves in hydraulic engineering are widespread. Designing a chute for uniform flow instead of for roll waves, the freeboard required is insufficient, so that water overtops the chute causing erosion, such as on earth dams. If bridges cross a chute carrying roll waves, flow choking may occur generating hydraulic jumps upstream, and again cause lateral overflow. If roll waves develop in tunnels, the flow may choke because wave crests become high enough to touch the tunnel ceiling causing complicated two-phase flow instead of supercritical free surface tunnel flow. Noting the large energy of hypercritical flow, these phenomena may cause massive damage, associated with complicated hydraulic flow features and extreme pressure fluctuations resulting eventually in the loss of a complete structure. Therefore, and especially under flood conditions, the presence of roll waves has to be included in a hydraulic design, to account for the determining flow conditions and to prevent damages due to unexpected flow features.
Transfer points
Published in D.V. Subba Rao, The Belt Conveyor, 2020
The design of chutes is influenced by the capacity, size and characteristics of material handled, speed and inclination of the belt and whether the belt is fed at single or multiple positions. The following are the six principles of design of chutes: Prevent plugging at impact pointsEnsure sufficient cross-sectional areaControl stream of particlesMinimize abrasive wear of chute surfaceControl generation of dustMinimize particle attrition.
Materials handling
Published in D.V. Subba Rao, Mineral Beneficiation, 2011
The ore is transported by wagon, truck, rope haulage, aerial tramway etc., from mine to beneficiation plant. Within the mill, the ore is transported by gravity and by conveyors. Gravity transport is the flow of material in which actuating force is gravity and is carried out in chutes and launders. Chutes are steeply inclined troughs of rectangular sections for the gravity transport of dry solids. Launders are gently sloping troughs of rectangular, triangular or semicircular sections for the gravity transport of suspensions of ore or mineral.
Investigation of Hydraulic Characteristics and Air Concentration of a 3D Simulated Air-Water Flow on a Spillway with an Aerator Device (A case study)
Published in ISH Journal of Hydraulic Engineering, 2022
Saeed Shayanseresht, Mohammad Manafpour
Shayanseresht (2014) studied the possibility of cavitation occurrence on the chute spillway of the Gavoshan Dam while there was no aerator device installed. It was concluded that the surface of the spillway (at distances 180 m to 225 m downstream of the spillway crest) exposes to the damages due to cavitation risk because the cavitation indices were found below the critical value of 0.2. The results of the present study are presented and discussed here for the Gavoshan spillway with an aerator device mounted on the chute bed. Bottom mean pressures along the spillway are shown in Figure 9(a). The mean pressures obtained experimentally are relevant to the spillway with aerator device except at the downstream of the spillway aerator where the bottom mean pressures were not measured on the physical model following the installation of the aeration system. Therefore, the pressure values at the downstream of the spillway are relevant to spillway without aerator device.
Experimental and numerical studies on orifice spillway aerator of Bunji Dam
Published in Journal of the Chinese Institute of Engineers, 2020
Muhammad Kaleem Sarwar, Ijaz Ahmad, Zulfiqar Ali Chaudary, Habib-Ur-Rehman Mughal
Figure 12 shows the plot comparing cavity pressure and Froude number after installing the ramp on spillway at various angles. Cavity pressure fluctuated significantly at low reservoir level (1620 m amsl). Figure 12 also indicated that Pn was increased with the increase in ramp angles. Installation of the ramp on spillway chute with increasing angle caused an increase in cavity length and air flow in the cavity which in turn increased the cavity pressures. Relatively low cavity pressure at high reservoir level was observed because of increasing shear force at air water interface. Results also showed that installation of the ramp at spillway chute of Bunji Dam spillway had decreased the nondimensional cavity pressure when spillway operated at high reservoir level.
A trap-and-haul fishway for upstream transfers of migrating fish at a challenging dam site
Published in Journal of Ecohydraulics, 2019
John H. Harris, David T. Roberts, Steven O’Brien, Brent Mefford, Kris S. Pitman
A source-and-sink regime likely prevails, with recruitment sources in the river downstream offsetting mortality upstream. Fishway conditions described by Pelicice and Agostinho (2008) as constituting “ecological traps” do not occur, as there are recruitment areas for potamodromous species available upstream of the dam, and downstream reaches have limited recruitment capacity. The dominance of catadromous species and absence of anadromous species are also relevant in this context. Discussions about a downstream fishway also faced practical issues including the restricted flow regime, the off-take towers’ remoteness from shoreline habitat and their limited capacity to attract fish into a downstream fishway. Additional challenges included the presence of multiple barriers (i.e. the 12 m drop below the spillway, the long spillway chute, the 440 m distance from dam crest to fishway site, and the dam wall itself). In view of the ecological aspects noted above, together with these practical issues, a fishway serving downstream-migrating fish at Hinze Dam was not considered justified. But in the Nerang River, assuming that fish transferred upstream are not necessary for sustaining recruitment by returning downriver, and pest fish are excluded, an upstream-only fishway can provide positive outcomes for fish diversity and abundance. Reservoir-based angling or electrofishing surveys could test ongoing population status.