scholarly journals Experimental study of pressure flushing of non-cohesive sediment through slotted pipe bottom outlet

RBRH ◽  
2021 ◽  
Vol 26 ◽  
Author(s):  
Felipe Azevedo Paulo ◽  
Aline Saupe Abreu ◽  
Maurício Dai Prá ◽  
Luiz Augusto Magalhães Endres ◽  
Rute Ferla ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cohesive Sediment ◽  
Reservoir Sedimentation ◽  
Sediment Characteristics ◽  
Direction Parallel ◽  
Sediment Removal ◽  
New Type ◽  
Bottom Outlets ◽  
Dimensionless Relation ◽  
Bottom Outlet

ABSTRACT Among several techniques for prevention and mitigation of reservoir sedimentation, bottom outlets arise as a means of removing sediment deposited close to the dam. Given the reduced sediment removal provided by traditional bottom outlets under pressure flushing conditions, this article proposes a new type of structure that aims to increase sediment removal in the direction parallel to the dam axis. An experimental installation was employed to evaluate its operation as a function of the variation of its diameter and flow and sediment characteristics. Through analysis of the bathymetry generated by the structure, a dimensionless relation for predicting the scour pit length was obtained, presenting good fitness to the experimental data.

scholarly journals Hybrid Artificial Intelligence Methods for Predicting Air Demand in Dam Bottom Outlet

2021 ◽  
Author(s):  
Aliakbar Narimani ◽  
Moghimi ◽  
Amir Mosavi
Keyword(s):  
Artificial Intelligence ◽  
Economic Value ◽  
Air Entrainment ◽  
Operating Conditions ◽  
Successful Operation ◽  
Volume Rate ◽  
Hydraulic Equipment ◽  
Bottom Outlets ◽  
Hybrid Artificial Intelligence ◽  
Bottom Outlet

In large infrastructures such as dams, which have a relatively high economic value, ensuring the proper operation of the associated hydraulic facilities in different operating conditions is of utmost importance. To ensure the correct and successful operation of the dam's hydraulic equipment and prevent possible damages, including gates and downstream tunnel, to build laboratory models and perform some tests are essential (the advancement of the smart sensors based on artificial intelligence is essential). One of the causes of damage to dam bottom outlets is cavitation in downstream and between the gates, which can impact on dam facilities, and air aeration can be a solution to improve it. In the present study, six dams in different provinces in Iran has been chosen to evaluate the air entrainment in the downstream tunnel experimentally. Three artificial neural networks (ANN) based machine learning (ML) algorithms are used to model and predict the air aeration in the bottom outlet. The proposed models are trained with genetic algorithms (GA), particle swarm optimization (PSO), i.e., ANN-GA, ANN-PSO, and ANFIS-PSO. Two hydrodynamic variables, namely volume rate and opening percentage of the gate, are used as inputs into all bottom outlet models. The results showed that the most optimal model is ANFIS-PSO to predict the dependent value compared with ANN-GA and ANN-PSO. The importance of the volume rate and opening percentage of the dams' gate parameters is more effective for suitable air aeration.

scholarly journals Enhanced hydrosuction performance for cohesive sediment removal in low-head reservoirs

2017 ◽  
Vol 8 (4) ◽  
pp. 491-497 ◽  
Author(s):  
P. Asiaban ◽  
S. Kouchakzadeh ◽  
S. Asiaban
Keyword(s):  
Cohesive Sediment ◽  
Sediment Removal ◽  
Low Head

scholarly journals Effect of Gate Selection on the Non-Cohesive Sedimentation in Irrigation Schemes

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2765
Author(s):  
Shaimaa Theol ◽  
Bert Jagers ◽  
Jigyasha Rai Yangkhurung ◽  
F.X. Suryadi ◽  
Charlotte de Fraiture
Keyword(s):  
Cohesive Sediment ◽  
Sediment Deposition ◽  
Hydraulic Parameters ◽  
Crop Water ◽  
Gate Operation ◽  
Control Structures ◽  
Sediment Removal ◽  
1D Model ◽  
The Impact ◽  
Selection Of

In order to cover the crop water requirements, flow control structures such as gates and weirs are used to transfer the desired amount of water from the canals to the field canals. This paper examines the impact of gate operation and the selection of gates on the deposition of non-cohesive sediment. The Delft3D model is used to simulate the effects of different scenarios regarding gate operation and the location of the gate that is opened. The model results showed that the gate selection affects not only hydraulic parameters but also morphological parameters. It was found that opening the gates closer to the offtake resulted in less sediment deposition at the entrance of the branch canal when compared to opening the gates further away. Gate selection can be used as a tool in sediment management. By alternating the opening of different gates sediments that are already deposited after opening one gate can be eroded when another gate is operated, thus minimizing the additional cost of sediment removal. The use of Delft3D proved beneficial as the selection of different gates leads to asymmetric sediment deposition patterns which would be missed when using a 1D model.

scholarly journals Planning and Analysis of Sedimentation Countermeasures in Hydropower Dams Considering Properties of Reservoir Sedimentation

2018 ◽  
Vol 13 (4) ◽  
pp. 702-708 ◽  
Author(s):  
Chihaya Onda ◽  
Tetsuya Sumi ◽  
Tsuyoshi Asahi ◽  
◽  
◽  
...  
Keyword(s):  
River Flow ◽  
Reservoir Sedimentation ◽  
Sediment Properties ◽  
Sediment Removal ◽  
Postwar Reconstruction ◽  
Sediment Routing ◽  
Routing Methods ◽  
Reconstruction Period ◽  
High Degree ◽  
Near Future

Sedimentation in hydropower reservoirs is one of the most important problems facing power generation. Many of the reservoirs our company’s dams, built in the postwar reconstruction period, have been storing up sedimentation for decades. The percentage of sedimentation is now considerable, about 9%, because of a combination of a high degree of sediment production and the river flow regime. We have been trying to excavate the sedimentation from the reservoirs to avoid aggradations of upstream riverbeds and to eliminate obstacles to intake and outlet functions. Considering sediment properties, we have carried out representative five different ways of managing reservoir sediment. At the Sakuma dam, which is comparatively large, provisional transporting inside the reservoir is the main countermeasure, but radical management will be required in the near future. At the Futatsuno dam and Taki dam, which are medium-sized, the current volume of sedimentation excavation is not sufficient to maintain the size of the reservoir, due to flow sedimentation. Sediment routing methods, such as bypassing, will therefore be urgently planned. At the Setoishi and Yambara dams, the testing of sediment sluicing or hydro-suction sediment removal systems has already started. Regarding sedimentation sluicing, we have studied the feasibility of sediment bypass tunnels and gated outlets in the dam reservoir that is unsuitable for sluicing with the existing spillway. We found that gated outlet will be effective. Although there are no quick remedies that can reduce reservoir sedimentation dramatically, there are some methods that may be suitable, considering the size, life and basin of each reservoir. Not only the technical feasibility, but also the economic advantages and ecological acceptability should be considered. To sustain reservoirs and hydropower, sedimentation should be managed effectively and adaptively, based on the specific conditions of each reservoir.

Electrostatic Generation in Dielectric Fluids: The Viscoelectric Effect

2005 ◽  
Author(s):  
Robert T. Balmer
Keyword(s):  
Experimental Data ◽  
Electric Fields ◽  
Theoretical Basis ◽  
Fluid Motion ◽  
Irreversible Thermodynamics ◽  
Reverse Effect ◽  
Dielectric Fluids ◽  
Electrostatic Generator ◽  
New Type ◽  
Mobile Charges

Simultaneous energy transfer modes have been known to interact to produce unusual “coupled” effects. This coupling now has its theoretical basis in the concept of entropy production (or dissipation or irreversibility) central to nonequilibrium irreversible thermodynamics. Over the years, many examples of coupled phenomena have been identified and studied (thermoelectricity, electrokinetics, piezoelectricity, and so forth). Electrohydrodynamics (the effect of fluid motion on electric fields and the reverse effect of electric fields on fluid motion) can be explained as a thermodynamically coupled phenomenon characterized by the viscous and electrical properties of a fluid that contain mobile charges at the molecular (e.g., ions) or macroscopic (e.g., dust) levels. This is called the “viscoelectric” effect. In the first part of this paper we apply the concepts of irreversible thermodynamics to electrohydrodynamic systems to develop the relevant relationships. The second describes experiments carried out with a new type of Couette electrostatic generator. The resulting experimental data is then discussed in light of the coupled phenomenon relations previously developed.

scholarly journals Modeling total resistance and form resistance of movable bed channels via experimental data and a kernel-based approach

2020 ◽  
Vol 22 (3) ◽  
pp. 528-540
Author(s):  
Seyed Mahdi Saghebian ◽  
Kiyoumars Roushangar ◽  
V. S. Ozgur Kirca ◽  
Roghayeh Ghasempour
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Laboratory Data ◽  
Gaussian Process Regression ◽  
Roughness Coefficient ◽  
Alluvial Channels ◽  
Sediment Characteristics ◽  
Modeling Process ◽  
The Impact ◽  
Movable Bed

Abstract An accurate prediction of roughness coefficient in alluvial channels is of substantial importance for river management. In this study, the total and form resistance in alluvial channels with dune bedform were assessed using experimental data. First, the data of experiments carried out at the Hydraulic Laboratory of University of Tabriz was used to investigate the impact of hydraulic and sediment parameters on roughness coefficient. Then, these data were combined with other laboratory data, and the total and bedform resistance were modeled via a Gaussian Process Regression (GPR) approach. For models, developing different input combinations were considered based on flow and sediment characteristics. The obtained results from the experiments showed that the Reynolds number has a better correlation with flow resistance in comparison with other hydraulic parameters. It was found that the roughness variations due to bedform are almost between 40 and 80% of the total roughness coefficient. Also, the obtained results proved the capability of the GPR method in the modeling process. It was found that the model which took the advantages of both flow and sediment characteristics performed better compared to the other models. The sensitivity analysis results showed that the Reynolds number has the most significant impact in the prediction process.

scholarly journals Nuclear spin scissors mode – experimental status

2018 ◽  
Vol 194 ◽  
pp. 04004
Author(s):  
Irina Molodtsova ◽  
Evgeny Balbutsev ◽  
Peter Schuck
Keyword(s):  
Experimental Data ◽  
Rare Earth ◽  
Nuclear Spin ◽  
Collective Motion ◽  
Systematic Analysis ◽  
Scissors Mode ◽  
Experimental Status ◽  
Rare Earth Nuclei ◽  
New Type

A new type of nuclear collective motion - the spin scissors mode - was predicted seven years ago. Promising signs of its existence in 232Th were found. We perform a systematic analysis of experimental data on M1 excitations in rare-earth nuclei to find traces of the spin scissors mode in this area. Obvious signs of its existence are demonstrated.

Crane Operation Using Hand-Motion and Machine Vision

2009 ◽  
Author(s):  
Kelvin Chen Chih Peng ◽  
William Singhose ◽  
Jonathan Fonseca
Keyword(s):  
Experimental Data ◽  
Image Processing ◽  
Motion Control ◽  
Processing System ◽  
Bridge Crane ◽  
Hand Motion ◽  
Input Shaper ◽  
Control Interface ◽  
New Type ◽  
Human Operators

Payload oscillation inherent to all cranes makes it challenging for human operators to manipulate payloads quickly, accurately, and safely. A new type of crane control interface that allows an operator to drive a crane by moving his or her hand freely in space has been implemented on an industrial bridge crane. An image processing system tracks the movement of a glove worn on the operator’s hand and its position is then used to drive the crane. Matlab simulations of the crane dynamics and hand-motion control were compared with actual experimental data. The results show that a combination of aggressive PD gains and an input shaper is able to generate the desired characteristics of fast payload response and low residual oscillations.

3D hydro-morphodynamic models as support tools for obtaining sustainable sediment management strategies of reservoirs

2020 ◽  
Author(s):  
Kilian Mouris ◽  
Leon Saam ◽  
Felix Beckers ◽  
Silke Wieprecht ◽  
Stefan Haun
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Management Strategies ◽  
Sediment Management ◽  
Transport Processes ◽  
Water Levels ◽  
Hydraulic Structures ◽  
Suspended Sediment Transport ◽  
Reservoir Sedimentation ◽  
Bottom Outlets

<p>Reservoir sedimentation reduces not only the available storage volume of reservoirs, but may also create other serious problems, such as an increase of bed levels or accumulations of nutrients and contaminants, which affect the environment. An increase in bed levels at the head of the reservoir can reduce flood safety and increase the risk for the surrounding areas. Deposited sediments close to the dam may block hydraulic structures, such as the bottom outlets, or, in case they enter the intake, lead to possible abrasion of plant components (e.g. wear of turbines and pipes).</p><p>Prior to reservoir construction, a pre-evaluation of the sediment yield from the catchment is usually performed by using soil erosion and sediment delivery models. However, the trapping efficiency is often only obtained by empirical approaches, such as Brune’s or Churchill’s curve, which are based on the capacity of the reservoir and the mean annual inflow. This is still common practice, although 3D hydro-morphodynamic models became powerful tools to numerically study sediment transport and reservoir sedimentation prior to the construction of reservoirs as well as during its operation.</p><p>Within this study, a fully 3D hydro-morphodynamic numerical model, based on the Reynolds-averaged Navier-Stokes equations, is applied to a case study to simulate, on the one hand suspended sediment transport within a hydropower reservoir and on the other hand a reservoir flushing operation as potential management scenario, with the goal to remobilize already deposited sediments and to release these sediments from the reservoir. The modeled reservoir has a total storage capacity of around 14 million m³, whereby the water level can fluctuate due to pumped-storage operation by 40.5 m (difference between the maximum operation level and the operational outlet). At the head is the natural inflow of two creeks into the reservoir and a lateral transition tunnel is located on the orographic right side, which collects several headwater streams from adjacent catchments.</p><p>Simulations are performed for different operation modes of the reservoir. The results clearly show that through active reservoir management (variation of water levels as well as using the momentum of the discharge from the transition tunnel) the sediment motion in the reservoir can be affected to a certain extent. It is for instance possible to almost completely avoid reservoir sedimentation in front of the dam and the hydraulic structures (water intake and bottom outlets) during sediment-laden flows when simultaneously high discharges are provided from the laterally located transition tunnel. The conducted simulation results of reservoir flushing also show that the success of the flushing operation is strongly dependent on the water level. As expected, flushing with full drawdown of the water level is the most efficient method to release sediments.</p><p>Through the detailed results of the 3D hydro-morphodynamic model, it is feasible to receive a deeper knowledge of the ongoing sediment transport processes within the studied reservoir. The gained knowledge can further be used to derive sustainable and efficient management strategies for the sediment management of the reservoir.</p>

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