Development of Closed-Conduit Roughness

2002 ◽  
Author(s):  
Stephen Coleman ◽  
Juan Fedele ◽  
Marcelo Garcia
Keyword(s):  
Closed Conduit

Optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits

2014 ◽  
Vol 70 (5) ◽  
pp. 871-877 ◽  
Author(s):  
Fahri Ozkan ◽  
M. Cihat Tuna ◽  
Ahmet Baylar ◽  
Mualla Ozturk
Keyword(s):  
Froude Number ◽  
High Speed ◽  
Water Mixture ◽  
High Speed Flow ◽  
Mixture Flow ◽  
Speed Flow ◽  
Aeration Efficiency ◽  
High Head ◽  
Closed Conduit ◽  
Air Vent

Oxygen is an important component of water quality and its ability to sustain life. Water aeration is the process of introducing air into a body of water to increase its oxygen saturation. Water aeration can be accomplished in a variety of ways, for instance, closed-conduit aeration. High-speed flow in a closed conduit involves air-water mixture flow. The air flow results from the subatmospheric pressure downstream of the gate. The air entrained by the high-speed flow is supplied by the air vent. The air entrained into the flow in the form of a large number of bubbles accelerates oxygen transfer and hence also increases aeration efficiency. In the present work, the optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits was studied experimentally. Results showed that aeration efficiency increased with the air-demand ratio to a certain point and then aeration efficiency did not change with a further increase of the air-demand ratio. Thus, there was an optimum value for the air-demand ratio, depending on the Froude number, which provides maximum aeration efficiency. Furthermore, a design formula for aeration efficiency was presented relating aeration efficiency to the air-demand ratio and Froude number.

Methodology considering surface roughness in UV water disinfection reactors

2016 ◽  
Vol 70 (6) ◽  
Author(s):  
Tipu Sultan ◽  
Jin-Soo Cho
Keyword(s):  
Surface Roughness ◽  
Dose Distribution ◽  
Water Disinfection ◽  
Iterative Approximation ◽  
Roughness Effects ◽  
Ansys Fluent ◽  
Pipe Surface ◽  
Uv Reactor ◽  
Uv Lamp ◽  
Closed Conduit

AbstractWater disinfection making use of an ultraviolet (UV) reactor is an attractive procedure because it does not produce any by-products. In this work, the effects of pipe roughness on the performance of a closed-conduit water disinfection UV reactor were investigated. In order to incorporate the surface roughness effects, a simple, stable, highly accurate model, better than any iterative approximation, was adopted in the numerical simulations. The analysis was carried out on the basis of two performance indicators: reduction equivalent dose (RED) and system dose distribution. The analysis was performed using a commercial computational fluid dynamics (CFD) tool (ANSYS Fluent). The fluence rate within the UV reactor was calculated using UVCalc3D. The pipe surface roughness resulted in longer pathogen residence times and higher dose distribution among the pathogens. The effect of pipe surface roughness on RED depends on the Reynolds number and relative roughness. Pipe surface roughness plays an important role because UV reactors for water disinfection operate at moderate Reynolds numbers. In addition, the positioning of the UV lamp in the reactor plays an important role in determining the RED of the reactor. Search criteria for lamp-positioning are also proposed in the current work. The proposed CFD methodology can be used to analyse the performance of closed-conduit reactors for water disinfection by UV.

Revealing magma degassing below closed-conduit active volcanoes: Geochemical features of volcanic rocks versus fumarolic fluids at Vulcano (Aeolian Islands, Italy)

Lithos ◽  
2016 ◽  
Vol 248-251 ◽  
pp. 272-287 ◽  
Author(s):  
Michela Mandarano ◽  
Antonio Paonita ◽  
Mauro Martelli ◽  
Marco Viccaro ◽  
Eugenio Nicotra ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Magma Degassing ◽  
Aeolian Islands ◽  
Closed Conduit ◽  
Fumarolic Fluids ◽  
Active Volcanoes

Closure to “Closed Conduit Flow”

1943 ◽  
Vol 108 (1) ◽  
pp. 1513-1516
Author(s):  
A. A. Kalinske ◽  
James M. Robertson
Keyword(s):  
Conduit Flow ◽  
Closed Conduit

Air Demand of a Hydraulic Jump in a Closed Conduit

2022 ◽  
Vol 148 (2) ◽  
Author(s):  
Pengcheng Li ◽  
David Z. Zhu ◽  
Tingyu Xu ◽  
Jian Zhang
Keyword(s):  
Hydraulic Jump ◽  
Closed Conduit

Optimization of lamp arrangement in a closed-conduit UV reactor based on a genetic algorithm

2016 ◽  
Vol 73 (10) ◽  
pp. 2526-2543 ◽  
Author(s):  
Tipu Sultan ◽  
Zeshan Ahmad ◽  
Jinsoo Cho
Keyword(s):  
Genetic Algorithm ◽  
Research Work ◽  
Technical Solution ◽  
Ansys Fluent ◽  
Design And Optimization ◽  
Systematic Methodology ◽  
Pathogen Transport ◽  
Dynamics Simulations ◽  
Uv Lamps ◽  
Closed Conduit

The choice for the arrangement of the UV lamps in a closed-conduit ultraviolet (CCUV) reactor significantly affects the performance. However, a systematic methodology for the optimal lamp arrangement within the chamber of the CCUV reactor is not well established in the literature. In this research work, we propose a viable systematic methodology for the lamp arrangement based on a genetic algorithm (GA). In addition, we analyze the impacts of the diameter, angle, and symmetry of the lamp arrangement on the reduction equivalent dose (RED). The results are compared based on the simulated RED values and evaluated using the computational fluid dynamics simulations software ANSYS FLUENT. The fluence rate was calculated using commercial software UVCalc3D, and the GA-based lamp arrangement optimization was achieved using MATLAB. The simulation results provide detailed information about the GA-based methodology for the lamp arrangement, the pathogen transport, and the simulated RED values. A significant increase in the RED values was achieved by using the GA-based lamp arrangement methodology. This increase in RED value was highest for the asymmetric lamp arrangement within the chamber of the CCUV reactor. These results demonstrate that the proposed GA-based methodology for symmetric and asymmetric lamp arrangement provides a viable technical solution to the design and optimization of the CCUV reactor.

Critical bed shear for initial movement of sediments on a combined lateral and longitudinal slope

2004 ◽  
Vol 35 (2) ◽  
pp. 153-164 ◽  
Author(s):  
Subhasish Dey
Keyword(s):  
Shear Stress ◽  
Flow Direction ◽  
Side Wall ◽  
Shear Stresses ◽  
Bed Shear Stress ◽  
Conduit Flow ◽  
Sloping Bed ◽  
Stress Ratios ◽  
Closed Conduit ◽  
Initial Movement

An experimental study on critical bed shear-stress for initial movement of non-cohesive sediment particles under a steady-uniform stream flow on a combined lateral (across the flow direction) and longitudinal (streamwise direction) sloping bed is presented. The aim of this paper is to ascertain that the critical bed shear-stress on a combined lateral and longitudinal sloping bed is adequately represented by the product of critical bed shear-stress ratios for lateral and longitudinal sloping beds. Experiments were carried out with closed-conduit flow, in two ducts having a semicircular invert section, with three sizes of sediments. In laboratory flumes, the uniform flow is a difficult – if not impossible – proposition for a steeply sloping channel, and is impossible to obtain in an adversely sloping channel. To avoid this problem, the experiments were conducted with a closed-conduit flow. The critical bed shear-stresses for experimental runs were estimated from side-wall correction. The experimental data agree satisfactorily with the results obtained from the proposed formula.

scholarly journals Impact of asymmetric lamp positioning on the performance of a closed-conduit UV reactor

2017 ◽  
Vol 8 (2) ◽  
pp. 225-235 ◽  
Author(s):  
Tipu Sultan ◽  
Zeshan Ahmad ◽  
Zahid Anwar ◽  
Muhammad Shahzad Khurram
Keyword(s):  
Uv Reactor ◽  
Closed Conduit
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