scholarly journals Investigations of Rake and Rib Structures in Sand Traps to Prevent Sediment Transport in Hydropower Plants

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3882
Author(s):  
Mads Mehus Ivarson ◽  
Chirag Trivedi ◽  
Kaspar Vereide
Keyword(s):  
Three Dimensional ◽  
Flow Distribution ◽  
Head Loss ◽  
Total Weight ◽  
Hydropower Plant ◽  
Trap Efficiency ◽  
Hydropower Plants ◽  
Sand Trap ◽  
Sst Turbulence Model ◽  
Three Dimensional Models

In order to increase the lifespan of hydraulic turbines in hydropower plants, it is necessary to minimize damages caused by sediment erosion. One solution is to reduce the amount of sediments by improving the design of sand trap. In the present work, the effects on sand trap efficiency by installing v-shaped rake structures for flow distribution and rib structures for sediment trapping is investigated numerically using the SAS–SST turbulence model. The v-shaped rake structures are located in the diffuser near the inlet of the sand trap, while the ribs cover a section of the bed in the downstream end. Three-dimensional models of the sand trap in Tonstad hydropower plant are created. The present study showed that integrating rib type structure can reduce the total weight of sediments escaping the sand trap by 24.5%, which leads to an improved sand trap efficiency. Consequently, the head loss in the sand trap is increased by 1.8%. By additionally including the v-shaped rakes, the total weight of sediments escaping the sand trap is instead increased by 48.5%, thus worsening the sand trap efficiency. This increases head loss by 12.7%. The results also show that turbulent flow commencing at the sand trap diffuser prevents the downstream settling of sediments with a diameter of less than one millimeter. The hydraulic representation of the numerical model is validated by comparison with particle image velocimetry measurements of the flow field from scale experiments and ADCP measurements from the prototype. The tested rib design has not previously been installed in a hydropower plant, and can be recommended. The tested v-shaped rakes have been installed in existing hydropower plants, but this practice should be reconsidered.

Development of a Numerical Based Correlation for Performance Losses due to Surface Roughness in Axial Turbines

2014 ◽  
Vol 30 (6) ◽  
pp. 631-642 ◽  
Author(s):  
S. A. Moshizi ◽  
M. H. Nakhaei ◽  
M. J. Kermani ◽  
A. Madadi
Keyword(s):  
Turbulence Model ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Streamline Curvature ◽  
Sst Turbulence Model ◽  
Stator Blade ◽  
Dimensional Models ◽  
Three Dimensional Models ◽  
Axial Turbines

AbstractIn the present work, a recently developed in-house 2D CFD code is used to study the effect of gas turbine stator blade roughness on various performance parameters of a two-dimensional blade cascade. The 2D CFD model is based on a high resolution flux difference splitting scheme of Roe (1981). The Reynolds Averaged Navier-Stokes (RANS) equations are closed using the zero-equation turbulence model of Baldwin-Lomax (1978) and two-equation Shear Stress Transport (SST) turbulence model. For the smooth blade, results are compared with experimental data to validate the model. Finally, a correlation between roughness Reynolds number and loss coefficient for both turbulence models is presented and tested for three other roughness heights. The results of 2D turbine blade cascades can be used for one-dimensional models such as mean line analysis or quasi-three-dimensional models e.g. streamline curvature method.

scholarly journals Retrofitting of Pressurized Sand Traps in Hydropower Plants

Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2515
Author(s):  
Wolfgang Richter ◽  
Kaspar Vereide ◽  
Gašper Mauko ◽  
Ola H. Havrevoll ◽  
Josef Schneider ◽  
...  
Keyword(s):  
Power Plants ◽  
Geometric Model ◽  
Scale Model ◽  
Cfd Simulations ◽  
Trap Efficiency ◽  
Sediment Size ◽  
Hydropower Plants ◽  
Sand Trap ◽  
Physical Scale ◽  
Scale Models

Unlined pressure tunnels in sound rock, combined with pressurized sand traps at the downstream end, allow for low-cost construction of hydropower tunnel systems. This design concept is utilized in hydropower plants across the world. Currently, many such power plants are being upgraded with higher installed capacity, which may result in challenges with the sand trap efficiency. A physical scale model test, accompanied by 3D CFD simulations of a case study pressurized sand trap, has been studied for economic retrofitting. The geometric model scale is 1:36.67 while the velocity scale and sediment scale are 1:1 (same average flow velocity and sediment size in model and prototype). This is currently an uncommon scaling approach but with several advantages, as presented in this paper. Various options for retrofitting were investigated. A combined structure of ramp and ribs was found to significantly improve the sediment trap efficiency. The main novelties from this work are the proposed design of the combined ramp and rib structure. Secondary results include an efficient setup for physical scale models of pressurized sand traps and a methodology that combines the benefits of 3D CFD simulations with physical scale models testing for sand trap engineering and design.

scholarly journals Flow control in a multichamber settling basin by sluice gates driven by a CFD and an ancillary analytical model

2021 ◽  
Author(s):  
Miloš V. Nikolić ◽  
Rade M. Karamarković
Keyword(s):  
Analytical Model ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Hydropower Plant ◽  
Cfd Model ◽  
Three Solutions ◽  
Small Hydropower ◽  
Local Flow ◽  
Settling Basin ◽  
Dimensional Flow

Abstract Unequal flow distribution between the chambers of a three-chamber settling basin causes its malfunction and endangers the turbines of a small hydropower plant. To equalize the flows, sluice gates are used. To find their positions, the following methodologies are considered: (1) measurements combined with trial-and-error method (TAE), (2) measurements with regression analysis (RA), (3) CFD model combined with TAE, (4) CFD model with RA, (5) CFD model supported by a one-dimensional flow model, and (6) CFD model with an analytical model. The additional models and RA are intended to speed up the solution finding. From the previous list, only the sixth methodology is applicable. The first four are not because of the weir design, and the fifth because of the three-dimensional flow character. Initially, the CFD model of the side-weir intake was developed and validated. Afterward, the analytical model, which consists of a system of three pressure drop equations for three parallel and partly imaginary streams, is formed. The local flow resistances in the analytical model are determined by the CFD model combined with RA. To equalize the flows, three solutions with (i) fix, (ii) fix in a range of flows, and (iii) variable positions of the sluice gates are analyzed.

scholarly journals Head Losses of Horizontal Bar Racks as Fish Guidance Structures

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 475 ◽  
Author(s):  
Julian Meister ◽  
Helge Fuchs ◽  
Claudia Beck ◽  
Ismail Albayrak ◽  
Robert M. Boes
Keyword(s):  
Flow Field ◽  
Fish Passage ◽  
Head Loss ◽  
Hydraulic Performance ◽  
Velocity Fields ◽  
Hydropower Plant ◽  
Protection Measures ◽  
Head Losses ◽  
Hydropower Plants ◽  
Fish Protection

Horizontal bar racks have been used as trash racks at hydropower plants since the 1920s. With the installation of the first horizontal bar rack bypass system at a hydropower plant as a downstream fish passage facility in 2006, these racks rapidly gained importance as fish protection measures. Since then, they have been installed at more than 100 small- to medium-sized hydropower plants in Europe. Despite the large number of installed racks, systematic investigations of the head losses and velocity fields were missing. On the basis of detailed hydraulic experimentation with a large number of rack parameters and including up-to-date foil-shaped bars, the layout of horizontal bar racks and their hydraulic performance were assessed in the current study. This paper reports the results of the rack head loss investigation, whereas the accompanying paper entitled Velocity Fields at Horizontal Bar Racks as Fish Guidance Structures focuses on the up- and downstream velocity fields. By applying foil-shaped bars instead of rectangular bars, the loss coefficient was reduced by more than 40%, depending on the rack configuration. Bottom and top overlays are used to increase the guidance efficiency for fish, sediments, and floating debris. However, the altered flow field results in increased head losses. A new set of equations is proposed to predict head losses for current horizontal bar racks, including overlays for various hydropower plant layouts. The predictions are compared to literature data.

Numerical Simulation for Hydraulic Characteristics of MLIS Hydropower Station

2013 ◽  
Vol 353-356 ◽  
pp. 2487-2491 ◽  
Author(s):  
Yuan Ding ◽  
Tong Chun Li ◽  
Min Zhe Zhou
Keyword(s):  
Numerical Simulation ◽  
Surface Water ◽  
Flow Velocity ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Head Loss ◽  
Hydropower Station ◽  
Hydraulic Characteristics ◽  
Multi Level ◽  
Intake Structure

Combined with a multi-level intake structure, using the standard two-equation turbulence model to carry on the three-dimensional numerical simulation for the hydraulic characteristics of this intake .The flow velocity, fluid flow distribution and head loss were analyzed and summarized. The vertical velocity distribution near the intake has been significantly changed after placed stop log gate, the flow velocity of the reservoir surface water near the intake increases significantly, more surface water enter the power plant unit, and the head loss increases greatly.

Plastic replicas as three-dimensional models of pulps

1975 ◽  
Vol 39 (8) ◽  
pp. 544-546
Author(s):  
HL Wakkerman ◽  
GS The ◽  
AJ Spanauf
Keyword(s):  
Three Dimensional ◽  
Dimensional Models ◽  
Three Dimensional Models

Validation of a Belt Model for Prediction of Hub Forces from a Rolling Tire4

2009 ◽  
Vol 37 (2) ◽  
pp. 62-102 ◽  
Author(s):  
C. Lecomte ◽  
W. R. Graham ◽  
D. J. O’Boy
Keyword(s):  
Internal Pressure ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Prediction Method ◽  
Analytical Models ◽  
Beam Model ◽  
Impedance Boundary ◽  
Bending Waves ◽  
Tire Rotation ◽  
Three Dimensional Models

Abstract An integrated model is under development which will be able to predict the interior noise due to the vibrations of a rolling tire structurally transmitted to the hub of a vehicle. Here, the tire belt model used as part of this prediction method is first briefly presented and discussed, and it is then compared to other models available in the literature. This component will be linked to the tread blocks through normal and tangential forces and to the sidewalls through impedance boundary conditions. The tire belt is modeled as an orthotropic cylindrical ring of negligible thickness with rotational effects, internal pressure, and prestresses included. The associated equations of motion are derived by a variational approach and are investigated for both unforced and forced motions. The model supports extensional and bending waves, which are believed to be the important features to correctly predict the hub forces in the midfrequency (50–500 Hz) range of interest. The predicted waves and forced responses of a benchmark structure are compared to the predictions of several alternative analytical models: two three dimensional models that can support multiple isotropic layers, one of these models include curvature and the other one is flat; a one-dimensional beam model which does not consider axial variations; and several shell models. Finally, the effects of internal pressure, prestress, curvature, and tire rotation on free waves are discussed.

Role of micro-hydropower plants in socio-economic development of rural Afghanistan

2020 ◽  
pp. 1-7
Author(s):  
Mohammad Airaj Firdaws Sadiq ◽  
Najib Rahman Sabory ◽  
Mir Sayed Shah Danish ◽  
Tomonobu Senjyu
Keyword(s):  
Distribution System ◽  
Energy Demand ◽  
Economic Life ◽  
Hydropower Plant ◽  
Decent Work ◽  
Hydropower Plants ◽  
Development Goals ◽  
The Government ◽  
Decentralized Energy ◽  
Energy Options

Afghanistan hosts the Hindu Kush, an extension of the Himalaya mountains that act as water sources for five major rivers flowing through Afghanistan. Most of these rivers provide promise for the construction of water dams and installment of micro hydropower plants (MHP). Although civil war and political strife continue to threaten the country for more than four decades, the Afghan government introduced strategic plans for the development of the country. In 2016 Afghanistan introduced the Afghanistan National Peace and Development (ANPD) Framework at Brussels de-signed to support Afghanistan’s progress towards achieving the SDGs (Sustainable Development Goals). This study discussed the 7th Goal (ensuring access to affordable, reliable, and sustainable energy for all) and 8th Goal (promoting sustained, inclusive and sustainable economic growth, full and productive employment and decent work for all) alignment in Afghanistan. The Afghan gov-ernment acknowledges its responsibility to provide electricity for all of its citizens, but this can only be achieved if the government can secure a reliable source of energy. Afghanistan’s mountainous terrain provides a challenge to build a central energy distribution system. Therefore this study looks for alternative solutions to the energy problems in Afghanistan and explores feasibility of micro-hydropower plant installations in remote areas. This study evaluated socio-economic im-pacts of micro-hydropower plants in the life of average residents. We focused on one example of a micro hydropower plant located in Parwan, conducted interviews with local residents, and gath-ered on-site data. The findings in this study can help policymakers to analyze the effects of devel-opment projects in the social and economic life of residents. It will encourage the government and hopefully the private sector to invest in decentralized energy options, while the country is facing an ever-growing energy demand.

In Silico Identification and Molecular Characterization of Extracellular Cathepsin L Proteases from Giardia duodenalis

2020 ◽  
Vol 17 (4) ◽  
pp. 342-351
Author(s):  
Sergio A. Durán-Pérez ◽  
José G. Rendón-Maldonado ◽  
Lucio de Jesús Hernandez-Diaz ◽  
Annete I. Apodaca-Medina ◽  
Maribel Jiménez-Edeza ◽  
...  
Keyword(s):  
In Silico ◽  
Cathepsin L ◽  
Three Dimensional ◽  
Giardia Duodenalis ◽  
Evolutionary Genetics ◽  
Extracellular Proteins ◽  
In Silico Identification ◽  
Dimensional Models ◽  
Three Dimensional Models

Background: The protozoan Giardia duodenalis, which causes giardiasis, is an intestinal parasite that commonly affects humans, mainly pre-school children. Although there are asymptomatic cases, the main clinical features are chronic and acute diarrhea, nausea, abdominal pain, and malabsorption syndrome. Little is currently known about the virulence of the parasite, but some cases of chronic gastrointestinal alterations post-infection have been reported even when the infection was asymptomatic, suggesting that the cathepsin L proteases of the parasite may be involved in the damage at the level of the gastrointestinal mucosa. Objective: The aim of this study was the in silico identification and characterization of extracellular cathepsin L proteases in the proteome of G. duodenalis. Methods: The NP_001903 sequence of cathepsin L protease from Homo sapienswas searched against the Giardia duodenalisproteome. The subcellular localization of Giardia duodenaliscathepsin L proteases was performed in the DeepLoc-1.0 server. The construction of a phylogenetic tree of the extracellular proteins was carried out using the Molecular Evolutionary Genetics Analysis software (MEGA X). The Robetta server was used for the construction of the three-dimensional models. The search for possible inhibitors of the extracellular cathepsin L proteases of Giardia duodenaliswas performed by entering the three-dimensional structures in the FINDSITEcomb drug discovery tool. Results: Based on the amino acid sequence of cathepsin L from Homo sapiens, 8 protein sequences were identified that have in their modular structure the Pept_C1A domain characteristic of cathepsins and two of these proteins (XP_001704423 and XP_001704424) are located extracellularly. Threedimensional models were designed for both extracellular proteins and several inhibitory ligands with a score greater than 0.9 were identified. In vitrostudies are required to corroborate if these two extracellular proteins play a role in the virulence of Giardia duodenalisand to discover ligands that may be useful as therapeutic targets that interfere in the mechanism of pathogenesis generated by the parasite. Conclusion: In silicoanalysis identified two proteins in the Giardia duodenalisprotein repertoire whose characteristics allowed them to be classified as cathepsin L proteases, which may be secreted into the extracellular medium to act as virulence factors. Three-dimensional models of both proteins allowed the identification of inhibitory ligands with a high score. The results suggest that administration of those compounds might be used to block the endopeptidase activity of the extracellular cathepsin L proteases, interfering with the mechanisms of pathogenesis of the protozoan parasite Giardia duodenalis.

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