A comparative study of pre-aeration effects on hydraulic jump air–water flow properties at high Froude numbers

2021 ◽  
Author(s):  
Rongcai Tang ◽  
Ruidi Bai ◽  
Hang Wang
Keyword(s):  
Comparative Study ◽  
Water Flow ◽  
Hydraulic Jump ◽  
Flow Properties

scholarly journals Uniform flow and energy dissipation of hydraulic-jump-stepped spillways

2020 ◽  
Vol 20 (4) ◽  
pp. 1546-1553
Author(s):  
Yu Zhou ◽  
Jianhua Wu ◽  
Fei Ma ◽  
Jianyong Hu
Keyword(s):  
Energy Dissipation ◽  
Water Flow ◽  
Hydraulic Jump ◽  
Flow Region ◽  
Uniform Flow ◽  
Stepped Spillway ◽  
Flow Depth ◽  
Clear Water ◽  
Air Concentration ◽  
Stepped Spillways

Abstract In skimming flow, a uniform flow can be achieved and the flow depth, velocity and air concentration remain constant if a stepped spillway is sufficiently long. In this study, physical model experiments were performed to investigate the uniform characteristics and energy dissipation of a hydraulic-jump-stepped spillway, which is a new type of stepped spillway for increasing the unit discharge capacity and energy dissipation. Based on the redefinition of uniform flow, experimental results show that at a given stepped spillway slope, a smaller height for the beginning of the uniform flow region, a greater uniform aerated flow depth and a greater uniform equivalent clear water flow depth can be obtained as compared with the traditional stepped spillway due to strong aeration in the aeration basin. Under the condition of uniform flow, the energy dissipation rate of stepped spillways can be estimated by the equivalent clear water flow depth with given inflow conditions. Compared with the traditional stepped spillway, the uniform flow over the hydraulic-jump-stepped spillway has a smaller specific energy, revealing that the hydraulic-jump-stepped spillway is more advantageous for dissipating energy, especially at large unit discharges.

scholarly journals Transient Air-Water Flow and Air Demand following an Opening Outlet Gate

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
James Yang ◽  
Ting Liu ◽  
Wenhong Dai ◽  
Penghua Teng
Keyword(s):  
Water Flow ◽  
Hydraulic Jump ◽  
Three Dimensional ◽  
Cfd Simulations ◽  
Wire Ropes ◽  
Air Supply ◽  
Flow Features ◽  
Demand Rate ◽  
Air Pockets ◽  
Bottom Outlets

In Sweden, the dam-safety guidelines call for an overhaul of many existing bottom outlets. During the opening of an outlet gate, understanding the transient air-water flow is essential for its safe operation, especially under submerged tailwater conditions. Three-dimensional CFD simulations are undertaken to examine air-water flow behaviors at both free and submerged outflows. The gate, hoisted by wire ropes and powered by AC, opens at a constant speed. A mesh is adapted to follow the gate movement. At the free outflow, the CFD simulations and model tests agree well in terms of outlet discharge capacity. Larger air vents lead to more air supply; the increment becomes, however, limited if the vent area is larger than 10 m2. At the submerged outflow, a hydraulic jump builds up in the conduit when the gate reaches approximately 45% of its full opening. The discharge is affected by the tailwater and slightly by the flow with the hydraulic jump. The flow features strong turbulent mixing of air and water, with build-up and break-up of air pockets and collisions of defragmented water bodies. The air demand rate is several times as much as required by steady-state hydraulic jump with free surface.

On the applicability of Washburn law: study of mercury and water flow properties in cement-based materials

2004 ◽  
Vol 37 (2) ◽  
pp. 107-113 ◽  
Author(s):  
A. Aït-Mokhtar ◽  
O. Amiri ◽  
P. Dumargue ◽  
A. Bouguerra
Keyword(s):  
Water Flow ◽  
Flow Properties ◽  
Cement Based Materials
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