scholarly journals Selection of a turbulence model to calculate the temperature profile near the surface of VVER-1000 fuel assemblies in the NPP spent fuel pool

2021 ◽  
Vol 7 (2) ◽  
pp. 79-84
Author(s):  
Aleksandra V. Voronina ◽  
Sergey V. Pavlov
Keyword(s):  
Experimental Data ◽  
Natural Convection ◽  
Fuel Assembly ◽  
Turbulence Model ◽  
Cfd Simulation ◽  
Experimental Studies ◽  
Calculated Data ◽  
Spent Fuel ◽  
Average Deviation ◽  
Ansys Fluent

The paper considers the problem of selecting a turbulence model to simulate natural convection near the surface of a VVER-1000 fuel assembly unloaded from the reactor by computational fluid dynamics (CFD simulation) methods. The turbulence model is selected by comparing the calculated data obtained using the Ansys Fluent software package with the results of experimental studies on the natural convection near the surface of a heated vertical plate immersed in water, which simulates the side face of the VVER-1000 fuel assembly in a first approximation. Two-parameter semi-empirical models of turbulence, k-ε and k-ω, are considered as those most commonly used in engineering design. The calculated and experimental data were compared based on the excessive temperature of the plate surface and the water temperature profiles in the turbulent boundary layer for convection modes with a Rayleigh number of 8∙1013 to 3.28∙1014. It has been shown that the best agreement with experimental data, with an average deviation not exceeding ~ 8%, is provided by the RNG k-ε model which is recommended to be used to simulate natural convection near the surface of VVER-1000 FAs in the NPP spent fuel storage pool.

Strength and Deformation of Combined Beams with Side Reinforced Plates

2019 ◽  
Vol 968 ◽  
pp. 234-239
Author(s):  
Talyat Azizov ◽  
Oleksii Melnik ◽  
Oleksandr Myza
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Calculated Data ◽  
Concrete Plate ◽  
Combined Action ◽  
Strength And Deformation ◽  
Concrete Plates ◽  
Good Agreement

The results of experimental studies of combined beams consisting of a stone part, reinforced with side reinforced concrete plates are given. Experimentally shown the viability of the proposed structures. The conditions for ensuring the combined action of a stone beam and a reinforced concrete plate are given. Cases are shown when one-sided plates can be used and when double-sided reinforced concrete plates can be used. A comparison of experimental data with the data calculated by the authors developed methods is given. A good agreement between theoretical and calculated data is shown.

scholarly journals Experimental studies and numerical simulation of coolant hydrodynamics in the inlet area of nuclear reactor fuel assembly

2018 ◽  
Vol 245 ◽  
pp. 09017
Author(s):  
Sergei Dmitriev ◽  
Alexander Khrobostov ◽  
Maksim Legchanov ◽  
Alexander Dobrov
Keyword(s):  
Numerical Simulation ◽  
Fuel Assembly ◽  
Cfd Simulation ◽  
Complex Geometry ◽  
Experimental Studies ◽  
Energy Resource ◽  
Reactor Fuel ◽  
Reactor Unit ◽  
Inlet Region ◽  
Reactor Fuel Assembly

An innovative core with an increased energy resource was used when designing RITM-200 reactor unit. The paper presents the results of experimental and numerical simulation of hydrodynamic processes occurring in the inlet region of the RITM reactor fuel assembly model. Computational mesh of fuel assembly, containing ~ 22 million elements was created using Ansys ICEM CFD. The values of relative axial velocities in several cross sections at the inlet to the bundle of fuel elements are obtained. At the inlet to the fuel rods bundle the velocity field is not uniform, due to the complex geometry of the fuel assembly. The obtained results of CFD-simulation can be used to determine the input boundary conditions for subchannel programs of the core thermal-hydraulic analysis. This allows taking into account uneven flow rate distribution in subchannels due to the complex geometry of the fuel assembly inlet region.

CFD Simulation of Slug Dissipation in an Enlarged Impacting Tee

2019 ◽  
Author(s):  
Mobina Mohammadikharkeshi ◽  
Mazdak Parsi ◽  
Ramin Dabirian ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Experimental Data ◽  
Void Fraction ◽  
Cfd Simulation ◽  
Petroleum Industry ◽  
Production Operation ◽  
Cfd Simulations ◽  
Ansys Fluent ◽  
Transient Model ◽  
Diameter Pipe ◽  
Computational Fluid Dynamics Cfd

Abstract Slug flow, which commonly occurs in the petroleum industry, is not always a desired flow pattern due to production operation problems it may cause in pipelines and processing facilities. To mitigate these problems, flow conditioning devices such as multiphase flow manifolds and slug catchers are used, where dissipation of slugs occurs in downward flow or in larger diameter pipe sections. Tee-junctions are important parts of these flow conditioning devices. In this work, Computational Fluid Dynamics (CFD) simulations are conducted using ANSYS/FLUENT 17.2 to investigate slug dissipation in an Enlarged Impacting Tee-Junction (EIT). An Eulerian–Eulerian MultiFluid VOF transient model in conjunction with the standard k-ε turbulent model is used to simulate slug dissipation in an EIT geometry. The EIT consists of a 0.05 m ID 10 m long inlet, which is connected to the center of a 0.074 m ID 5.5 m long section that forms the EIT branches. Moreover, experimental data are acquired on slug dissipation lengths in a horizontal EIT with a similar geometry as in the CFD simulations. The CFD results include the mean void fraction and cross-sectionally averaged void fraction time series in the EIT for different gas and liquid velocities. These results provide the inlet slug length and dissipation length in the EIT branches. The CFD results are evaluated against the experimental data demonstrating that the slug dissipation occurring in EIT branches can be predicted by simulation.

Modeling Heat Transfer in Spent Fuel Transfer Cask Neutron Shields: A Challenging Problem in Natural Convection

2010 ◽  
Author(s):  
James A. Fort ◽  
Judith M. Cuta ◽  
Chris S. Bajwa ◽  
Emilio Baglietto
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Steady State ◽  
Natural Convection ◽  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
The United States ◽  
Challenging Problem ◽  
Spent Fuel ◽  
Neutron Shield

In the United States, commercial spent nuclear fuel is typically moved from spent fuel pools to outdoor dry storage pads within a transfer cask system that provides radiation shielding to protect personnel and the surrounding environment. The transfer casks are cylindrical steel enclosures with integral gamma and neutron radiation shields. Since the transfer cask system must be passively cooled, decay heat removal from the spent nuclear fuel canister is limited by the rate of heat transfer through the cask components, and natural convection from the transfer cask surface. The primary mode of heat transfer within the transfer cask system is conduction, but some cask designs incorporate a liquid neutron shield tank surrounding the transfer cask structural shell. In these systems, accurate prediction of natural convection within the neutron shield tank is an important part of assessing the overall thermal performance of the transfer cask system. The large-scale geometry of the neutron shield tank, which is typically an annulus approximately 2 meters in diameter but only 10–15 cm in thickness, and the relatively small scale velocities (typically less than 5 cm/s) represent a wide range of spatial and temporal scales that contribute to making this a challenging problem for computational fluid dynamics (CFD) modeling. Relevant experimental data at these scales are not available in the literature, but some recent modeling studies offer insights into numerical issues and solutions. However, the geometries in these studies, and for the experimental data in the literature at smaller scales, all have large annular gaps that are not prototypic of the transfer cask neutron shield. This paper proposes that there may be reliable CFD approaches to the transfer cask problem, specifically coupled steady-state solvers or unsteady simulations; however, both of these solutions take significant computational effort. Segregated (uncoupled) steady state solvers that were tested did not accurately capture the flow field and heat transfer distribution in this application. Mesh resolution, turbulence modeling, and the tradeoff between steady state and transient solutions are addressed. Because of the critical nature of this application, the need for new experiments at representative scales is clearly demonstrated.

Influence of Inlet Boundary Conditions on Simulations of an Asymmetric Diffuser With the V2F Turbulence Model

2015 ◽  
Author(s):  
James Crawford ◽  
A. M. Birk
Keyword(s):  
Experimental Data ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Excellent Agreement ◽  
Turbulence Model ◽  
Two Dimensional ◽  
Ansys Fluent ◽  
Inlet Velocity

A set of numerical simulations were performed on an asymmetric, two dimensional diffuser using ANSYS Fluent 14.0, a commercially available RANS based CFD code. The ν′2¯-f turbulence model, which has previously been shown to be a good model for this geometry, was implemented through a user defined function, and the influence of inlet boundary conditions was evaluated. It was shown that the inlet velocity and turbulence profiles had a significant effect on the calculated performance of the diffuser, especially in terms of the onset of diffuser stall. It was shown that when the boundary conditions were set appropriately, excellent agreement with LES and experimental data was obtained.

CFD Study of Tidal Current Turbine Shroud for Initial Design Evaluation

2014 ◽  
Vol 679 ◽  
pp. 35-38 ◽  
Author(s):  
Azim Arshad ◽  
Shahrani Anuar ◽  
Ahmmad Shukrie ◽  
Rosdi Hussin
Keyword(s):  
Experimental Data ◽  
Tidal Current ◽  
Cfd Simulation ◽  
Ansys Fluent ◽  
Commercial Code ◽  
Simulation And Experiment ◽  
Tidal Current Turbine ◽  
Coefficient Of Velocity ◽  
Current Turbine ◽  
Good Agreement

CFD simulation of a tidal current turbine shroud was performed using Ansys FLUENT commercial code and comparison was made with experimental data. The simulation result obtained was in good agreement with the experimental data. The coefficient of velocity, Cv was in the range of approximately 1.2 to 1.4 for both simulation and experiment. The present study gave useful information on the viability of CFD simulation for the initial evaluation of shroud design performance.

An Assessment of Turbulence Models for S-Duct Diffusers With Flow Control

2013 ◽  
Author(s):  
S. P. Bhat ◽  
R. K. Sullerey
Keyword(s):  
Experimental Data ◽  
Flow Control ◽  
Turbulence Model ◽  
Flow Analysis ◽  
Turbulence Models ◽  
Experimental Results ◽  
Cfd Analysis ◽  
Duct Flow ◽  
Ansys Fluent ◽  
Sst Model

The selection of a turbulence model for a problem is not trivial and has to be done systematically after comparison of various models with experimental data. It is a well known fact that there is no such turbulence model which fits all problems ([3], [13]). The flow in S-duct diffuser is a very complex one where both separation and secondary flow coexist. Previous work by the author on CFD analysis of S-duct diffuser was done using k-ε-Standard model [1], however it has been seen that choosing other turbulence model may result in better capturing of the physics in such a problem. Also flow control, to reduce energy losses, is achieved using a technique called Zero Net Mass Flow (ZNMF), in which suction and vortex generation jets (VGJ) are combined and positioned at optimum location. A proper turbulence model has to be chosen for capturing these phenomena effectively. Extensive experimental data is available on this problem and ZNMF technique from previous work done by one of the authors which is used for validating the CFD results. Here the focus is on choosing the best turbulence model for the S-duct diffuser. Numerical (CFD) analysis is carried out using Ansys Fluent 13.0 with six turbulence models for the geometry with (ZNMF) and without (Bare duct) flow control and then compared with the experimental results. The turbulence models used are Spalart-Allmaras, three variants of k-ε – Standard, RNG and Realizable and two variants of k-ω – Standard and SST model. All the parameters of comparison are non-dimensionalized using the free stream properties, so that the results are applicable to a wider range of problems. This work is limited to incompressible flow analysis, as the experimental data is only available for low Mach number flows. Comparison of all these models clearly shows that results obtained using k-ω-SST model are very comparable to the experimental results for the bare duct (without flow control) and flow controlled duct both in terms of distribution of properties and aggregate results. Compressible flow analysis can be attempted to achieve reliable results in future with ZNMF using the best turbulence model based on this study.

scholarly journals COMPARISON OF AXIAL FAN ROTOR EXPERIMENTAL DATA WITH CFD SIMULATION

2016 ◽  
Vol 56 (1) ◽  
pp. 62 ◽  
Author(s):  
Aleš Prachař
Keyword(s):  
Experimental Data ◽  
Boundary Conditions ◽  
Cfd Simulation ◽  
Free Stream ◽  
Calculated Data ◽  
Experimental Simulation ◽  
Test Rig ◽  
Axial Fan ◽  
Axial Fans ◽  
Adequate Agreement

Data obtained from an experimental simulation on a new test rig for axial fans are compared to a CFD simulation. The Edge solver is used and the development needed for the simulation (boundary conditions, free stream consistency) is described. Adequate agreement between the measured and calculated data is observed.

3-D CFD Simulation of the Airflow over a Gable Roof with Different Elevations

2015 ◽  
Vol 769 ◽  
pp. 229-234
Author(s):  
Juraj Jr. Kralik
Keyword(s):  
Wind Tunnel ◽  
Turbulence Model ◽  
Cfd Simulation ◽  
Wind Tunnel Test ◽  
Turbulence Models ◽  
Accurate Method ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Pressure Coefficients ◽  
Gable Roof

The pressure coefficients on duo-pitched roofs of separated buildings are well described by several standards. Nowadays, there are various commercial or non-commercial programs which can predict the pressure coefficients. However, the most accurate method is to perform a wind tunnel test. The aim of this paper is to simulate the airflow over a gable roof with different elevations under ANSYS Fluent 14.0 program. Examined elevations of the gable roof are 5°, 15° and 30°. Classical two equation k-ε turbulence models based on Reynolds Averaged Navier-Stokes (RANS) equations simulation were performed. Performance of each turbulence model with the increasing angel of the roof was compared.

scholarly journals MODEL OF THE QUALITY-POWER INDICATOR OF A ROTARY DRUM MIXER

2020 ◽  
pp. 107-113
Author(s):  
А.В. Чупшев ◽  
В.В. Коновалов ◽  
К.П. Фудин
Keyword(s):  
Experimental Data ◽  
Initial Data ◽  
Statistical Model ◽  
Quality Indicators ◽  
Experimental Studies ◽  
Calculated Data ◽  
Design Parameters ◽  
Operating Parameters ◽  
Drum Mixer ◽  
Rotary Drum

На основании экспериментальных исследований в статье изложены вопросы повышения качественных показателей работы барабанного смесителя кормов, представлено описание его конструкции и принцип работы. Исследования проводились в соответствии с действующей методикой и материалами, представленными в статье. По результатам аппроксимации исходно рассчитанных значений качественно-мощностного показателя получена статистическая модель данного качественно-мощностного показателя (0,01 %∙кВт). Осуществлен анализ величины ошибок расчетных данных на предмет соответствия исходным данным. После обработки полученных экспериментальных данных приведено описание графических зависимостей по влиянию конструктивных параметров рабочего органа барабанного смесителя на качественно-мощностной показатель. Увеличение высоты установки лопастей нежелательно свыше 0,16 м, а увеличение количества лопастей свыше восемь штук приводит к резкому ухудшению количественно-мощностного показателя. Даны соответствующие выводы по применению исследуемых конструктивных и режимных параметров при работе барабанного смесителя. Based on experimental studies, the article presents the issues of improving the quality indicators of the drum feed mixer, describes its design and operating principle. The research was conducted in accordance with the current methodology and materials presented in the article. Based on the results of approximation of the initially calculated values of the quality-power indicator, a statistical model of this quality-power indicator (0.01% kW) is obtained. The value of errors in the calculated data is analyzed for correspondence with the initial data. After processing the obtained experimental data, the description of dependence diagrams on the influence of the design parameters of the working body of the drum mixer on the quality and power indicator is shown. An increase in the height of the installation of blades is undesirable over 0.16 m, and an increase in the number of blades over eight leads to a rapid deterioration in the quantity-power indicator. The relevant conclusions on the application of the studied design and operating parameters in the working of the drum mixer are presented.

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