scholarly journals Confined Plunging Liquid Jets for Dilution of Brine from Desalination Plants

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 856
Author(s):  
Ishita Shrivastava ◽  
Edward Eric Adams ◽  
Bader Al-Anzi ◽  
Aaron Chunghin Chow ◽  
Jongyoon Han
Keyword(s):  
Water Column ◽  
Penetration Depth ◽  
Water Surface ◽  
Liquid Jets ◽  
Laboratory Measurements ◽  
Surrounding Water ◽  
Plunging Jets ◽  
Desalination Plants ◽  
Negative Buoyancy

Confined plunging jets are investigated as potential outfalls for the discharge of desalination brine. Compared to offshore submerged outfalls that rely on momentum to induce mixing, plunging jets released above the water surface utilize both momentum and negative buoyancy. Plunging jets also introduce air into the water column, which can reduce the possibility of hypoxic zones. In contrast to unconfined plunging jets, confined plunging jets include a confining tube, or downcomer, around the jet, which increases the penetration depth of the bubbles and can provide better aeration. However, the presence of this downcomer can hinder mixing with surrounding water. Therefore, laboratory measurements of dilution are reported here and compared to the dilution of unconfined plunging jets. In addition, qualitative observations of bubble penetration depth are also used to discuss aeration potential. For designs that increase the bubble penetration depth as compared to unconfined plunging jets, results show that dilution decreases as the depth of the downcomer is increased. However, it is shown that confined plunging jets can be designed with a short downcomer to provide higher dilution than unconfined jets. The effect of the diameter of downcomer on dilution is also investigated and a non-monotonic effect is observed.

scholarly journals Unconfined Dense Plunging Jets Used for Brine Disposal from Desalination Plants

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 696
Author(s):  
Aaron C. Chow ◽  
Ishita Shrivastava ◽  
E. Eric Adams ◽  
Fahed Al-Rabaie ◽  
Bader Al-Anzi
Keyword(s):  
Water Column ◽  
Penetration Depth ◽  
Laboratory Experiments ◽  
Buoyant Jets ◽  
Air Bubble ◽  
Plunging Jets ◽  
Desalination Plants ◽  
Entrained Air ◽  
Neutrally Buoyant ◽  
Receiving Water

Laboratory experiments were conducted to measure entrained air bubble penetration depth and dilution of a dense vertical unconfined plunging jet to evaluate its performance as an outfall to dilute brine from desalination plants as well as a means to aerate water column. Experiments involved neutrally buoyant or dense plunging jets discharging in quiescent receiving water. The density difference between effluent and receiving water, the plunging jet length (height above water surface), and the receiving water salinity were varied in the experiments. Observed penetration depth for neutrally buoyant jets was somewhat greater than previously reported, and increased modestly with jet density. Increasing density also resulted in an increasing number of fine bubbles descending together with the dense plume. These observations can help guide the design of plunging jets to mitigate anoxic conditions in the water column when brine is introduced to a receiving water body, as with seawater desalination.

Scale and Configuration Effects of an Airchamber on PTO of Oscillating Water Column Type Wave Energy Converters

2021 ◽  
Author(s):  
Tomoki Ikoma ◽  
Shota Hirai ◽  
Yasuhiro Aida ◽  
Koichi Masuda
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Water Surface ◽  
Air Pressure ◽  
Scale Model ◽  
Linear Potential ◽  
Oscillating Water Column ◽  
Wave Energy Converters ◽  
Air Chamber ◽  
Energy Converters

Abstract Wave energy converters (WECs) have been extensively researched. The behaviour of the oscillating water column (OWC) in OWC WECs is extremely complex due to the interaction of waves, air, and turbines. Several problems must be overcome before such WECs can be put to practical use. One problem is that the effect of the difference in scale between a small-scale experimental model and a full-scale model is unclear. In this study, several OWC models with different scales and geometries were used in forced oscillation tests. The wave tank was 7.0 m wide, 24.0 m long, and 1.0 m deep. In the static water experiment, we measured the air pressure and water surface fluctuations in an air chamber. For the experiments, models with a box shape with an open bottom, a manifold shape with an open bottom, and a box shape with a front opening, respectively, were fabricated. Furthermore, 1/1, 1/2, and 1/4 scale models were fabricated for each shape to investigate the effects of scale and shape on the air chamber characteristics. Numerical calculations were carried out by applying linear potential theory and the results were compared with the experimental values. The results confirmed that the air chamber shape and scale affect the air pressure fluctuation and water surface fluctuation inside the OWC system.

scholarly journals Honeybees use their wings for water surface locomotion

2019 ◽  
Vol 116 (49) ◽  
pp. 24446-24451 ◽  
Author(s):  
Chris Roh ◽  
Morteza Gharib
Keyword(s):  
Water Surface ◽  
Adhesive Force ◽  
Jet Stream ◽  
Forward Movement ◽  
Surrounding Water ◽  
Air Water Interface ◽  
Acceleration And Deceleration ◽  
Periodic Acceleration ◽  
Speed Up ◽  
Horizontal Momentum

Honeybees display a unique biolocomotion strategy at the air–water interface. When water’s adhesive force traps them on the surface, their wetted wings lose ability to generate aerodynamic thrust. However, they adequately locomote, reaching a speed up to 3 body lengths·s−1. Honeybees use their wetted wings as hydrofoils for their water surface propulsion. Their locomotion imparts hydrodynamic momentum to the surrounding water in the form of asymmetric waves and a deeper water jet stream, generating ∼20-μN average thrust. The wing kinematics show that the wing’s stroke plane is skewed, and the wing supinates and pronates during its power and recovery strokes, respectively. The flow under a mechanical model wing mimicking the motion of a bee’s wing further shows that nonzero net horizontal momentum is imparted to the water, demonstrating net thrust. Moreover, a periodic acceleration and deceleration of water are observed, which provides additional forward movement by “recoil locomotion.” Their water surface locomotion by hydrofoiling is kinematically and dynamically distinct from surface skimming [J. H. Marden, M. G. Kramer, Science 266, 427–430 (1994)], water walking [J. W. M. Bush, D. L. Hu, Annu. Rev. Fluid Mech. 38, 339–369 (2006)], and drag-based propulsion [J. Voise, J. Casas, J. R. Soc. Interface 7, 343–352 (2010)]. It is postulated that the ability to self-propel on a water surface may increase the water-foraging honeybee’s survival chances when they fall on the water.

scholarly journals Buried Depth of a Submarine Pipeline Based on Anchor Penetration

2019 ◽  
Vol 7 (8) ◽  
pp. 257
Author(s):  
Xueyuan Zhu ◽  
Qinglong Hao ◽  
Jie Zhang
Keyword(s):  
Numerical Simulation ◽  
Penetration Depth ◽  
Water Depth ◽  
Calculation Method ◽  
Water Surface ◽  
Submarine Pipeline ◽  
Projected Area ◽  
Actual Measurement ◽  
Calculation Results ◽  
The Relationship

Anchor penetration is an important issue involved in the study of submarine pipeline damage accidents. To explore the penetration of a ship’s anchor under certain conditions, this study investigated the motion and force of an anchor and formulated a calculation method for the bottoming speed of an anchor. Meanwhile, the depth of anchor penetration was calculated under different conditions according to bottoming speed through programming. Finally, the reliability of the calculation method for the penetration depth was verified by comparing the actual measurement and the numerical simulation. On the basis of the findings, the calculation results were further analyzed, and conclusions were derived regarding the relationship between anchor mass, the horizontal projected area of the anchor, the anchor height on the water surface, and water depth. The conclusions provide suggestions for the application of anchor penetration in terms of seabed depth with certain reference values.

Theoretical Modelling of Free Falling Wedges Entering the Water Surface: Part I — Wedge Motions

2013 ◽  
Author(s):  
Jingbo Wang
Keyword(s):  
Numerical Simulations ◽  
Froude Number ◽  
Penetration Depth ◽  
Water Surface ◽  
Theoretical Models ◽  
Theoretical Modelling ◽  
Rapid Variation ◽  
Drag Coefficients ◽  
Free Falling ◽  
Theoretical Results

As the first of two companion papers, theoretical models are proposed to describe the motions of free falling wedges vertically entering the water surface at Froude numbers: 1 ≤ Fn < 9 (Here, the Froude number is defined as Fn=V0/gc0). The time evolutions of the penetration depth, the velocity and the acceleration are analyzed and expressed explicitly The maximum and average accelerations are predicted. The drag (slamming) coefficients are extensively studied. It is found that for the light wedge the transient drag coefficients have slow variation in the first half stage and rapid variation in the last half stage, and for the heavy wedge the transient drag coefficients vary slowly during the whole stage and can be treated as constant. The theoretical results are compared with numerical simulations by nonlinear BEM (Wang & Faltinsen (2010, 2013)), and good agreements are obtained.

scholarly journals Experimental Study of a Moored Floating Oscillating Water Column Wave-Energy Converter and of a Moored Cubic Box

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1834 ◽  
Author(s):  
Minghao Wu ◽  
Vasiliki Stratigaki ◽  
Peter Troch ◽  
Corrado Altomare ◽  
Tim Verbrugghe ◽  
...  
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Water Surface ◽  
Wave Energy Converter ◽  
Surface Elevation ◽  
Mooring Line ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Large Wave ◽  
Water Surface Elevation

This paper describes experimental research on a floating moored Oscillating Water Column (OWC)-type Wave-Energy Converter (WEC) carried out in the wave flume of the Coastal Engineering Research Group of Ghent University. This research has been introduced to cover the existing data scarcity and knowledge gaps regarding response of moored floating OWC WECs. The obtained data will be available in the future for the validation of nonlinear numerical models. The experiment focuses on the assessment of the nonlinear motion and mooring-line response of a 1:25 floating moored OWC WEC model to regular waves. The OWC WEC model motion has 6 degrees of freedom and is limited by a symmetrical 4-point mooring system. The model is composed of a chamber with an orifice on top of it to simulate the power-take-off (PTO) system and the associated damping of the motion of the OWC WEC model. In the first place, the motion response in waves of the moored floating OWC WEC model is investigated and the water surface elevation in the OWC WEC chamber is measured. Secondly, two different mooring-line materials (iron chains and nylon ropes) are tested and the corresponding OWC WEC model motions and mooring-line tensions are measured. The performance of these two materials is similar in small-amplitude waves but different in large wave-amplitude conditions. Thirdly, the influence of different PTO conditions is investigated by varying the diameter of the top orifice of the OWC WEC model. The results show that the PTO damping does not affect the OWC WEC motion but has an impact on the water surface elevation inside the OWC chamber. In addition, an unbalanced mooring configuration is discussed. Finally, the obtained data for a moored cubic model in waves are presented, which is a benchmarking case for future validation purposes.

scholarly journals Experiment on the Breakup of Liquid Jets in Different Cross-Airflows

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Tian Deng ◽  
Wei Chen ◽  
Xing-ming Ren ◽  
Shuai Jiang ◽  
Chao-hua Yuan
Keyword(s):  
Penetration Depth ◽  
High Speed ◽  
Velocity Ratio ◽  
Flux Ratio ◽  
Liquid Jets ◽  
Uniform Shear ◽  
Jet Trajectory ◽  
Uniform Case ◽  
Jet Penetration ◽  
Exponential Relation

The experiment is conducted with a high-speed camera to investigate the breakup processes of liquid jets in uniform, shear-laden, and swirling cross-airflows. The liquid used in the test is water, the nozzle diameter is 2 mm, and the liquid-to-air momentum flux ratio q ranges from 5 to 3408.5. The results indicate that liquid jets break up to form small droplets in the uniform cross-airflow. There is an exponential relation between the broken position and q. In the shear-laden cross-airflow, the penetration depth of the jet is similar to that of the uniform case, both of which increase with the increase of q. When q and the mean Weber number are the same as the uniform case, the penetration depth of the jet increases by 25% when the velocity ratio of the upper and lower inlets is UR=5; the jet penetration depth decreases by 47.2% when the ratio of UR=0.2 and the jet breaks up quickly and the atomization effect will be better. In the swirling cross-airflow, the jet trajectory is similar to the uniform case and also satisfies the exponential property. When the swirl is weak (swirling number SN=0.49), the jet penetration depth increases compared to the uniform case; when the swirl is strong (SN=0.82), the cross-swirling airflow restrains the jet penetration depth.

Net Environmental - Economic Benefit Analysis Model

2003 ◽  
Vol 2003 (1) ◽  
pp. 995-1002 ◽  
Author(s):  
W. Koops ◽  
M.G.D. Smit ◽  
R. de Vos
Keyword(s):  
Environmental Economic ◽  
Water Column ◽  
Food Chain ◽  
Economic Benefit ◽  
Water Surface ◽  
Ecological Effect ◽  
Benefit Analysis ◽  
Analysis Model ◽  
Response Option ◽  
Response Options

ABSTRACT To be able to compare various response strategies for oil spill response a Net Environmental – Economic Benefit Analysis model (NEEBA) has been developed by TNO. This model consists of an oil behaviour module, a response module and an ecological effect module. In the oil behaviour module a quantitative division of the oil volume over the different compartments (air, water surface and water column) is determined on the basis of spreading, transport and weathering. This module determines also the fate of the remaining oil after one of the response options has been applied. With the ecological effect module the effects on organisms at the water surface, in the water column and on the sea floor are determined. In order to come up with one benefit score a simplified weighing method has been chosen to compare the effects on different species. The NEEBA score is therefore expressed in costs, using the costs of fish as basis. The “costs” of the other organisms in relation to fish are dependent on their place in the food chain. For each step in the food chain a factor ten has been applied. In other words 1 kg of birds equals 10 kg of fish and 100 kg of Zooplankton. To account for seasonal fluctuations the model can be adjusted by changing the densities of the different organisms over the year. The methodology, developed in MS excel, can be used by policy makers and decision takers to assist in choosing the most appropriate response option. The model interface consists of an input window, a default window with several variables and defaults and two output windows. In the input window parameters such as volume, density and viscosity of the oil but also meteorological and hydrological information can be filled in. In the default window parameters like the densities of the different organisms, weighing factors, costs, water type, etc, can be varied. The response option can be varied with respect to mobilization time, number of units deployed and capacity. The NEEBA model is a valuable tool to support decision-making and gives insight in the environmental effects related to a particular response option. The NEEBA model shows that there is a specific role for the different response options. Each option has a window of opportunity in which the use is most optimal. The tool can be used for preplanning as well as during actual spills. The model will be developed further to increase its value and realism

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