scholarly journals Fish Response to Turbulence Generated Using Multiple Randomly Actuated Synthetic Jet Arrays

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1715
Author(s):  
Samuel F. Harding ◽  
Robert P. Mueller ◽  
Marshall C. Richmond ◽  
Pedro Romero-Gomez ◽  
Alison H. Colotelo
Keyword(s):  
Turbulent Flow ◽  
Dose Response ◽  
Oncorhynchus Tshawytscha ◽  
Significant Loss ◽  
Synthetic Jet ◽  
Test Facility ◽  
Hydroelectric Power ◽  
Mean Flow ◽  
Test Volume ◽  
Power Stations

Hydroelectric power stations generate turbulent flow conditions, which represent a potentially significant hydraulic stressor to fish passing through the turbine system. A test facility has been developed using two randomly actuated synthetic jet arrays (RASJAs) of 25 independent submersible pumps to generate a turbulent flow field for biological dose-response testing. The novel elements of this approach include the ability to control the exposure duration within a test volume due to low mean flow velocity as well as the capacity to scale the turbulence levels as a function of pump capacity. Juvenile Chinook salmon (Oncorhynchus tshawytscha) were subjected to the turbulent flow regime with average turbulence kinetic energy per unit mass of 0.089 m 2 / s 2 for periods of 2 min and 10 min. No significant loss of equilibrium or disorientation was observed after exposure for either duration at the level of turbulence achieved in this prototype. Further scaling of this approach is required to generate a complete dose-response relationship.

Numerical Prediction of Flow in a Nuclear Fuel Bundle With Various Turbulence Models

2002 ◽  
Author(s):  
Wang Kee In ◽  
Dong Seok Oh ◽  
Tae Hyun Chun
Keyword(s):  
Turbulent Flow ◽  
Nuclear Fuel ◽  
Turbulence Models ◽  
Convective Transport ◽  
Stress Model ◽  
Convergence Criteria ◽  
Mean Flow ◽  
Numerical Predictions ◽  
Viscosity Models ◽  
Fuel Bundle

The numerical predictions using the standard and RNG k–ε eddy viscosity models, differential stress model (DSM) and algebraic stress model (ASM) are examined for the turbulent flow in a nuclear fuel bundle with the mixing vane. The hybrid (first-order) and curvature-compensated convective transport (CCCT) schemes were used to examine the effect of the differencing scheme for the convection term. The CCCT scheme was found to more accurately predict the characteristics of turbulent flow in the fuel bundle. There is a negligible difference in the prediction performance between the standard and RNG k-ε models. The calculation using ASM failed in meeting the convergence criteria. DSM appeared to more accurately predict the mean flow velocities as well as the turbulence parameters.

Turbulent flow between counter-rotating concentric cylinders: a direct numerical simulation study

2008 ◽  
Vol 615 ◽  
pp. 371-399 ◽  
Author(s):  
S. DONG
Keyword(s):  
Turbulent Flow ◽  
Large Scale ◽  
Outer Cylinder ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Taylor Vortex ◽  
Small Scale ◽  
Mean Flow ◽  
Concentric Cylinders ◽  
High Reynolds

We report three-dimensional direct numerical simulations of the turbulent flow between counter-rotating concentric cylinders with a radius ratio 0.5. The inner- and outer-cylinder Reynolds numbers have the same magnitude, which ranges from 500 to 4000 in the simulations. We show that with the increase of Reynolds number, the prevailing structures in the flow are azimuthal vortices with scales much smaller than the cylinder gap. At high Reynolds numbers, while the instantaneous small-scale vortices permeate the entire domain, the large-scale Taylor vortex motions manifested by the time-averaged field do not penetrate a layer of fluid near the outer cylinder. Comparisons between the standard Taylor–Couette system (rotating inner cylinder, fixed outer cylinder) and the counter-rotating system demonstrate the profound effects of the Coriolis force on the mean flow and other statistical quantities. The dynamical and statistical features of the flow have been investigated in detail.

Assessment of Different Turbulence Models in Helically Coiled Pipes Through Comparison With Experimental Data

2012 ◽  
Author(s):  
Marco Colombo ◽  
Antonio Cammi ◽  
Marco E. Ricotti
Keyword(s):  
Turbulent Flow ◽  
Great Influence ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Test Facility ◽  
Wall Functions ◽  
Pressure Drops ◽  
Fully Developed Turbulent Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Helical Geometry

This paper deals with a comprehensive study of fully developed single-phase turbulent flow and pressure drops in helically coiled channels. To the aim, experimental pressure drops were measured in an experimental campaign conducted at SIET labs, in Piacenza, Italy, in a test facility simulating the Steam Generator (SG) of a Generation III+ integral reactor. Very good agreement is found between data and some of the most common correlations available in literature. Also more data available in literature are considered for comparison. Experimental results are used to assess the results of Computational Fluid Dynamics (CFD) simulations. By means of the commercial CFD package FLUENT, different turbulence models are tested, in particular the Standard, RNG and realizable k-ε models, Shear Stress Transport (SST) k-ω model and second order Reynolds Stress Model (RSM). Moreover, particular attention is placed on the different types of wall functions utilized through the simulations, since they seem to have a great influence on the calculated results. The results aim to be a contribution to the assessment of the capability of turbulence models to simulate fully developed turbulent flow and pressure drops in helical geometry.

The Numerical Simulation of Turbulent Flow in Semi-Closed Rotor-Stator Cavity

2016 ◽  
Author(s):  
Guohu Luo ◽  
Shengde Wang ◽  
Hong Shen ◽  
Zhenqiang Yao
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Boundary Layers ◽  
Pressure Difference ◽  
Tangential Velocity ◽  
Reynolds Stress Model ◽  
Mean Flow ◽  
Closed Cavity ◽  
Turbulent Field ◽  
Effects Of Rotation

The present work numerically considered the turbulent flow in a semi-closed rotor-stator cavity with a superimposed throughflow based on Reynolds Stress Model (RSM). The mean flow structure and turbulent field in the semi-closed cavity (SC) were identified by comparison with the flow in open cavity (OC) and closed cavity (CC). Then the effects of rotation Reynolds number, ranging from 1 × 106 to 4 × 106, on the flow in SC were investigated. The superimposed flow noticeably decreases the tangential velocity, resulting that the pressure difference between central hub and periphery in SC is greater than the OC but less than the CC. The flow in SC belongs to Stewartson type in the region between inlet and outlet, but to Bachelor type between outlet and periphery. Around the outlets, the flow is greatly affected, especially for turbulent field, where the turbulence intensities maintain at higher levels outside the two boundary layers. With the increase of Reynolds number, the tangential velocity goes up, resulted the attenuation of jet impinging effects, the shrinking of affected zones by outlets and the enlargement of pressure difference. Moreover, with the Bödewadt layer moving toward the central hub, the turbulence intensities increase inside two boundary layers but decrease outside them. Consequently, the flow is transited to Stewartson and then Batchelor type.

scholarly journals Analysis of floodable areas of the Angara river

2020 ◽  
Vol 223 ◽  
pp. 03002
Author(s):  
Gachenko Andrey ◽  
Hmelnov Alexey
Keyword(s):  
Model Building ◽  
Hydroelectric Power Station ◽  
Application Software ◽  
Hydroelectric Power ◽  
Power Station ◽  
Terrain Model ◽  
Power Stations ◽  
Littoral Area ◽  
Bratsk Reservoir

In this work, the authors present a technology for riverside terrain model building that has been tested on a number of scientific projects to study the littoral area of tail race of the Irkutsk Hydroelectric Power Station and the Bratsk Reservoir. This model is used for forecasting changes in the reservoir shorelines associated with wastewater in the cascade of hydroelectric power stations. The technology described in the work was approved to solve a number of practical problems and showed its effectiveness. Specialized application software was developed and terrain data from various sources were used to specify and detail the end result.

scholarly journals MODELING OF COMPATIBLE WORK OF DISTRIBUTED POWER SOURCES OF ELECTRIC POWER AND CENTRALISED POWER SUPPLY

2018 ◽  
pp. 189-195
Author(s):  
Petro Lezhnyuk ◽  
Iryna Hunko ◽  
Juliya Malogulko ◽  
Iryna Kotylko ◽  
Lіudmyla Krot
Keyword(s):  
Power Supply ◽  
Power Plants ◽  
Solar Power ◽  
Energy Sources ◽  
Hydroelectric Power Station ◽  
Hydroelectric Power ◽  
Distributed Energy ◽  
Power Stations ◽  
Asynchronous Generator ◽  
Solar Power Plants

Urgency of the research. Current trends of distributed generation development in Ukraine indicate a rapid generation in-crease from renewable energy plants. Most developed countries gradually refuse from the fossil fuels use and invest more and more to the “green” energy. Therefore, there is a need for a detailed study of the operation conditions of distributed energy sources due to their instability, as well as the processes that arise in distribution electric networks with diverse types of distributed energy sources. Target setting. In the producing process of power energy by distributed energy sources due to the increase in their num-ber, there are situations where several renewable sources of energy operate to only one system of buses. Thus, such distributive networks acquire the features of a local power system, which complicates the control process of such systems, and also there is a problem with the electricity supply of consumers. Actual scientific researches and issues analysis. The analysis of publications suggests that in literature more attention is paid to studying the operating modes of solar power plants, or small hydroelectric power plants. However, almost no attention was paid to the study of their cooperation work. Uninvestigated parts of general matters defining. Only a few works are devoted to the study of the cooperation of the diverce sources of distributed energy sources in the local electrical systems. That is why, their impact on power distribution networks and on the grid in general has not been studied extensively. The research objective. In this article was considered the influence of asynchronous generators on small hydroelectric power plants on the operation modes of distribution electrical networks, and were investigated the processes that are occurring in local power systems with different types of distributed energy sources. The statement of basic materials. Based on the research results, was developed a computer model of a such system in the PS CAD software environment. Two solar stations and one small hydroelectric power station with an asynchronous generator were connected to the power supply. It was shown the simulation of two modes of operation: a joint operation of a small hydroelectric power station, two solar power stations and a power supply center; a joint operation of a small hydroelectric pow-er plant, two solar power stations and a power supply disconnected. Conclusions. As a result of computer simulation, it is shown that by switching on a small hydroelectric power plant with an asynchronous generator in the case of an emergency shutdown of centralized power supply, it is possible to restore the work of solar power plants, and thus partially or completely restore the power supply of consumers.

scholarly journals Patterns of Changes in Average Annual Water Temperatures of the Rivers of the Arctic Zone of Russia Associated with Climate Changes

2020 ◽  
pp. 8-22
Author(s):  
Keyword(s):  
Climate Changes ◽  
Rank Correlation ◽  
The Arctic ◽  
Hydroelectric Power ◽  
Spearman Rank Correlation ◽  
Hydrological Characteristics ◽  
Power Stations ◽  
Annual Water ◽  
Spearman Rank Correlation Test ◽  
Annual Water Temperature

The paper considers changes in temperature regime of rivers flowing northerner than 60th latitude. The investigation bases on data about average monthly water temperatures from 90 hydrological gages for the period 1960-2012. Annual water temperatures for this period were calculated according to the generally accepted method as average monthly temperature from May to September and according to the proposed in this paper calculation method for the entire period with positive water temperatures. It is shown that the calculation of annual water temperatures only from the average monthly temperatures from May to October, underestimates annual water temperature. The paper estimates changes in the average annual water temperatures calculated by both methods over the period 1991–2012 compared to 1961-1990 These periods cover intensive climate change, as well as the time after the construction of the largest hydroelectric power stations. Statistical analyzes of the obtained series for trends (according to the Spearman rank correlation test) and series uniformity disturbances (Mann-Whitney U-test) were carried out. A significant increase in the average annual water temperatures in rivers on most rivers of the Russian Arctic is shown. The greatest changes are observed in the territories of Yakutia. Significant changes are also noted on the Kola Peninsula. At the same time, the magnitude of the changes depends on various hydrological characteristics of the basin. Significant changes to date have occurred in less than 50% of the investigated rivers.

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