Investigation of Hydraulic Characteristics and Air Concentration of a 3D Simulated Air-Water Flow on a Spillway with an Aerator Device (A case study)

2020 ◽  
pp. 1-13
Author(s):  
Saeed Shayanseresht ◽  
Mohammad Manafpour
Keyword(s):  
Water Flow ◽  
Hydraulic Characteristics ◽  
Air Concentration

Flow over a stepped chute with and without macro-roughness elements

2004 ◽  
Vol 31 (5) ◽  
pp. 880-891 ◽  
Author(s):  
Mehmet Ali Kökpinar
Keyword(s):  
Water Flow ◽  
High Speed ◽  
Length Distribution ◽  
Air Entrainment ◽  
Air Concentration ◽  
Bubble Frequency ◽  
Two Phase ◽  
Air Bubble ◽  
Roughness Elements ◽  
Stepped Chute

High-speed two-phase flows over a 30° stepped flume were experimentally investigated using macro-roughness elements. The roughness elements included combinations of steps and horizontal strips. Local values of air concentration, air bubble frequency, and mean chord lengths were measured by a fiber-optical instrumentation system in the air–water flow region. The range of unit discharge of water was varied from 0.06 to 0.20 m2/s. Three step configurations were studied: (i) without macro-roughness elements, (ii) with macro-roughness elements on each step, and (iii) with macro-roughness elements on each second step (AMR configuration). The results were compared in terms of onset flow conditions and internal air–water flow parameters such as local air concentration, mean air bubble chord length distribution, and air bubble frequency in the skimming flow regime. It was observed that the AMR configuration produced the maximum free-surface aeration among the other configurations. This alternative step geometry has potential for less cavitation damage than conventional step geometry because of the greater air entrainment.Key words: stepped chute, air-entrainment, air-water flow properties, macro-roughness elements, skimming flow.

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.

Freshwater pathways and litter

2020 ◽  
Author(s):  
María Cabrera Fernández
Keyword(s):  
Water Quality ◽  
Water Flow ◽  
The European Union ◽  
Marine Litter ◽  
Data Field ◽  
Different Types ◽  
Protection Area ◽  
Union Directive ◽  
Special Protection

<p>In recent years, there has been an increasing number of studies about freshwater micro-litter  and how it ends up in the ocean. Nevertheless, macro-litter studies are not common in freshwater landscapes and yet less frequent among rivers. Almost always, research is focused on estuaries rather than rivers.</p><p>The Asociación Paisaje Limpio has been developed, for some years, several studies as an affordable methodology to measure macro-litter in rivers throughout its.</p><p>This way, our methodology is a combination between research and action. We don’t just tackle the macro-litter data field, but also identify specific litter problems along the river. We act through campaigns, agreement for companies and public administrations, etc.</p><p>A need have been observed to combined different types of methodology to monitoring different types of rivers in order to be able to draw a conclusion:</p><ul><li><strong>Visual counting</strong>: counting floating macro-litter on <strong>surface </strong>using RIMMEL app.</li> <li>By the <strong>riverbank,</strong>through a <strong>Citizen Science</strong> tool create by Asociación Paisaje Limpio and Asociación Vertidos Cero, called <strong>eLitter</strong>. Elitter is harmonized with other marine-litter methodologies (Marine litter watch, MARNOBA in Spain) and its litter classification is based on OSPAR protocol.</li> <li>If the <strong>riverbed </strong>is accessible eLitter is also used, but when is not accessible a dredge "Van Veen" have been used instead. This method has been applied in other marine-litter projects on seabed.</li> <li><strong>Floating booms</strong>: it lets us know plastics rate in captured floating litter, and the water flow extrapolation.</li> <li><strong>Nets from a kayak</strong>: to study the plastic concentration  in <strong>the water column </strong>and the water flow extrapolation.</li> <li><strong>Water quality general analysis:</strong>this analysis is useful to support the hypothesis about litter’s source in a river, mainly where the source is the sewage as happens with wet wipes, ear sticks...</li> </ul><p>-<strong>Case study</strong>: river Lagares, a spanish river in Pontevedra, Galicia. The river Lagares flows into the Atlantic, in a Special Protection Area (SPA), a designation under the European Union Directive on the Conservation of Wild Birds.</p><p>The Asociación Paisaje Limpio is working on this river since 2018. We have applied the different methodologies explained before, in the river Lagares.</p>

scholarly journals The Effect of Hydraulic Characteristics on Algal Bloom in an Artificial Seawater Canal: A Case Study in Songdo City, South Korea

Water ◽  
2014 ◽  
Vol 6 (2) ◽  
pp. 399-413 ◽  
Author(s):  
Seung Lee ◽  
Sooyoung Kim ◽  
Moonil Kim ◽  
Kyoung Lim ◽  
Younghun Jung
Keyword(s):  
South Korea ◽  
Algal Bloom ◽  
Artificial Seawater ◽  
Hydraulic Characteristics
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