CFD Simulation of 5×5 Rod Bundles With Split-Type Spacers

2013 ◽  
Author(s):  
K. Podila ◽  
J. Bailey ◽  
Y. F. Rao ◽  
M. Krause
Keyword(s):  
Cfd Simulation ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Atomic Energy ◽  
Rod Bundles ◽  
Spacer Grid ◽  
Two Phase ◽  
Ansys Fluent ◽  
Computational Fluid Dynamics Cfd ◽  
Canada Limited

Atomic Energy of Canada Limited (AECL) has initiated a program to develop Computational Fluid Dynamics (CFD) capability for simulating single- and two-phase flows in rod-bundles. In the current work, a 5×5 rod assembly with a split-type spacer grid is simulated with ANSYS Fluent 14 using unsteady simulations with a fully conformal hybrid mesh (wall y+∼30). This work represents results of AECL’s recent participation in the OECD/NEA organized CFD benchmarking exercise on the MATiS-H experiment performed at the Korean Atomic Energy Research Institute (KAERI). The sensitivity to turbulence models is tested using the standard k-ε and the Reynolds stress model (RSM). Reasonable agreement is achieved between the calculated and experimental velocity values in the region close to the spacer grid, whereas turbulence intensity values are underpredicted compared to the experiments.

Development and Application of Single-Phase CFD Methodology for Estimating Flow Field in Rod Bundles

2013 ◽  
Author(s):  
Fujun Gan ◽  
Libing Zhu ◽  
Jiazheng Liu ◽  
Yixiong Zheng ◽  
Xing Tong
Keyword(s):  
Flow Field ◽  
Single Phase ◽  
Nuclear Reactor ◽  
Cfd Simulation ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Rod Bundles ◽  
Engineering Research ◽  
Computational Fluid Dynamics Cfd ◽  
Nuclear Reactor Safety

Computational Fluid Dynamics (CFD) simulation has been increasingly used in Nuclear Reactor Safety (NRS) analysis to describe safety–relevant phenomena occurring in the reactor coolant system in greater detail. In this paper, the work about single-phase CFD simulation of rod bundles conducted in Shanghai Nuclear Engineering Research & Design Institute (SNERDI) is introduced. A single-phase methodology based on commercial software STAR-CCM+ is developed to simulate the flow field and temperature distribution in fuel rod bundles. Solid model is simply introduced at first. Mesh types, including tetrahedral, polyhedral and trimmer, are compared in order to select the most best one with both good accuracy and less cost. Several turbulence models available in STAR-CCM+, including standard k-epsilon model, realizable k-epsilon model (RKE), shear stress transport k-omega model (SST k-omega), and Reynolds stress model (RSM) are investigated. Trimmed mesh and RKE turbulence model with two-layer all y+ model are finally employed for following calculations. Vortex structures downstream of mixing vanes is qualitatively compared with Particle Image Velocity (PIV) results, and good agreement is achieved. The present method will be further refined in order to play significant role in future optimal design of fuel assembly (FA) grid.

CFD Simulation of Round Impinging Jet and Comparison With Experimental Data

2016 ◽  
Author(s):  
H. Arabnejad ◽  
A. Mansouri ◽  
S. A. Shirazi ◽  
B. S. McLaury
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Cfd Simulation ◽  
Turbulence Models ◽  
Impinging Jet ◽  
Reynolds Stress Model ◽  
Ansys Fluent ◽  
Target Wall ◽  
Computational Fluid Dynamics Cfd ◽  
Better Than

In this work, fluid dynamics of a turbulent round impinging jet has been studied using Computational Fluid Dynamics (CFD) and the results have been compared with experimental data from the literature. The fluid was water with density of 1000 kg/m3 and the average velocity of the submerged jet was kept constant at 10.7 m/s while the liquid viscosity varied from 1 cP to 100 cP. Different turbulence models including k-ε, k-ω and Reynolds Stress Model (RSM) have been employed in ANSYS FLUENT and the predicted axial and radial velocity profiles at various distances from the wall are compared with LDV data. It was observed that at locations away from the target wall, predicted velocities are comparable to the measured velocities for all the viscosities. However, near the wall, the deviation between the CFD predictions and experimental measurements become noticeable. The performance of k-ω model and RSM are found to be better than the k-ε model especially for the highest viscous fluid, but no model was found to be superior for all conditions and at all locations.

scholarly journals Design and CFD Simulation of Knockout Drum

2020 ◽  
Vol 10 (4) ◽  
pp. 181-198
Author(s):  
Yazen Munaf Ali ◽  
Dr Saad Nahi Saleh ◽  
Wameed Abdulhassan Ayash ◽  
Saramd Zaki Ghani ◽  
Sudad Adil Salih
Keyword(s):  
Cfd Simulation ◽  
Flow Behavior ◽  
Local Area ◽  
Cfd Model ◽  
Two Phase ◽  
Fluid Mixture ◽  
Ansys Fluent ◽  
Black Smoke ◽  
The North ◽  
Computational Fluid Dynamics Cfd

Recently, the emission of black smoke over local area of Basra Oil Company from flare system represents a big problem facing the company and causing huge pollution in the surrounding environment. The main reason of emission black smoke is carryover of droplets of the rest hydrocarbons such as condensate and droplets of crude oil by gases which are came from degassing stations facility in the north Rumelia field, southern Iraq.  In this study, a design methodology was developed for designing the knockout drum, and different design criteria were used in sizing and selecting the drum based on the specification of the inlet fluid mixture. Three designs of knockout drums with respect to the gas conditions were performed. The horizontal knockout drum with a diameter of 2.5 m and length of 5.5 m was simulated using a Computational Fluid Dynamics (CFD) model (ANSYS FLUENT 15.0). The CFD model predicted very well the two-phase flow behavior and proved the need for a vortex breaker at the liquid outlet. The CFD simulation revealed quantitatively that the design configuration of the knockout drum performed the separation of condensate droplets from natural gas with excellent efficiency.

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.

scholarly journals EFFECT OF GALLERIES ON THE WIND FLOW STRUCTURE AND POLLUTANT TRANSPORT WITHIN STREET CANYONS WITH OR WITHOUT FACADE ROUGHNESS ELEMENTS (BALCONIES)

2020 ◽  
Vol 7 (12) ◽  
pp. 45-59
Author(s):  
V. A. Karkoulias ◽  
P. E. Marazioti ◽  
D. P. Georgiou ◽  
E. A. Maraziotis
Keyword(s):  
Flow Field ◽  
Concentration Distribution ◽  
Cfd Simulation ◽  
Field Structure ◽  
Flow Structures ◽  
Street Canyons ◽  
Ansys Fluent ◽  
Roughness Elements ◽  
Computational Fluid Dynamics Cfd ◽  
The Vertical Distribution

This paper investigates how the structure of the flow field and the vertical distribution of the pollutant concentration near the wall facades of street canyons are affected by the presence of some elements such as street level galleries. Numerical results are presented for various gallery geometries in combination with facade roughness elements (balconies) for a canyon of an aspect ratio equal to h/w=2.33. The results were obtained by a Computational Fluid Dynamics (CFD) simulation employing the ANSYS-FLUENT suite that incorporated the k-e turbulent (RNG) model. The simulation generated several flow structures inside the canyon (mainly vortices), whose characteristic properties (e.g. number, strength and size) are discussed in terms of the effect of the galleries on the flow field structure and the roughness generated by the building façade balconies. The results indicate a significant influence on both the flow field structure and the mass concentration distribution of the polluting particles.

Computer Analysis of S822 Aerofoil Section for Blades of Small Wind Turbines at Low Wind Speed

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Prachi R. Prabhukhot ◽  
Aditya R. Prabhukhot
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Cfd Simulation ◽  
Maximum Velocity ◽  
Small Scale ◽  
Blade Profile ◽  
Ansys Fluent ◽  
Low Wind Speed ◽  
Upward Direction ◽  
Computational Fluid Dynamics Cfd

The power generated in wind turbine depends on wind speed and parameters of blade geometry like aerofoil shape, blade radius, chord length, pitch angle, solidity, etc. Aerofoil selection is the crucial factor in establishing the efficient wind turbine. More than one aerofoil in a blade can increase the efficiency further. Previous studies of different aerofoils have shown that efficiency of small scale wind turbine increases when NREL S822 aerofoil is used for wind speed on and above 10 m/s. This paper introduces a study on effect of low wind speed (V = 5 m/s) on performance of blade profile. Aerofoils NREL S822/S823 are used for microwind turbine with S823 near root and S822 near tip. Blade of 3 m radius with spherical tubercles over entire span is analyzed considering 5 deg angle of attack. The computational fluid dynamics (CFD) simulation was carried out using ANSYS fluent to study the behavior of blade profile at various contours. The study shows that blade experiences maximum turbulence and minimum pressure near trailing edge of the tip of blade. The region also experiences maximum velocity of the flow. These factors result in pushing the aerofoil in upward direction for starting the wind turbine to rotate at the speed as low as 5 m/s.

CFD Simulation of Effect of Interphase Forces and Turbulence Models on Gas–Liquid Two-Phase Flows in Non-Industrial Aluminum Electrolysis Cells

JOM ◽  
2017 ◽  
Vol 69 (9) ◽  
pp. 1589-1599 ◽  
Author(s):  
Shuiqing Zhan ◽  
Jianhong Yang ◽  
Zhentao Wang ◽  
Ruijie Zhao ◽  
Jun Zheng ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Turbulence Models ◽  
Aluminum Electrolysis ◽  
Two Phase Flows ◽  
Two Phase ◽  
Electrolysis Cells ◽  
Industrial Aluminum

CFD Simulation of a Supersonic Steam Ejector for Refrigeration Application

2016 ◽  
Author(s):  
Liju Su ◽  
Ramesh K. Agarwal
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Fluid Pressure ◽  
Turbulence Models ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Working Fluid ◽  
Entrainment Ratio ◽  
Ansys Fluent ◽  
Entrainment Velocity

Supersonic steam ejectors are widely used in many industrial applications, for example for refrigeration and desalination. The experimental evaluation of the flow field inside the ejector is relatively difficult and costly due to the occurrence of shock after the velocity of the steam reaches over the sonic level in the ejector. In this paper, numerical simulations are conducted to investigate the detailed flow field inside a supersonic steam (water vapor being the working fluid) ejector. The commercial computational fluid dynamics (CFD) flow solver ANSYS-Fluent and the mesh generation software ANSYS-ICEM are used to predict the steam performance during the mixing inside the ejector by employing two turbulence models, the k-ω SST and the k-ε realizable models. The computed results are validated against the experimental data. The effects of operating conditions on the efficiency of the ejector such as the primary fluid pressure and condenser pressure are studied to obtain a better understanding of the mixing process and entrainment. Velocity contours, pressure plots and shock region analyses provide a good understanding for optimization of the ejector performance, in particular how to increase the entrainment ratio.

Blood Flow Simulations of Particle Trapping in Models of Arterial Bifurcations

2020 ◽  
Author(s):  
Qihang Xu ◽  
Ramesh K. Agarwal
Keyword(s):  
Blood Flow ◽  
Laminar Flow ◽  
Turbulence Models ◽  
Discrete Phase Model ◽  
Inlet Pipe ◽  
Particle Trapping ◽  
Two Phase ◽  
Ansys Fluent ◽  
Bifurcation Angle ◽  
Velocity Magnitude

Abstract This paper describes the particle trapping mechanism in blood flow in different arterial bifurcation models. For validation of CFD calculations, a T-junction model and a Y-junction model are analyzed. In both the models, there is one inlet pipe with two outlet pipes creating a symmetric bifurcation at some angle from the centerline of the inlet pipe. Naiver-Stokes (RANS) equations are solved for single phase laminar flow using the commercial CFD software ANSYS Fluent. After validation, Eulerian simulations are performed by using the Discrete Phase Model (DPM) for two-phase flow with particles injected in different bifurcation models with bifurcation angle of an outlet pipe varying from 80° to 100° w.r.t the centerline of the inlet pipe (90° being the bifurcation angle of T-junction). By changing the average Reynolds number of the flow and the injected particle diameters, the mechanism of particle trapping is investigated in laminar flow. The contours of velocity magnitude, pressure and wall shear stress are also obtained and analyzed. It is found that the particle trapping increases as the bifurcation angle decreases from 90° and becomes negligible as the bifurcation angle increases from 90°. This is a very important result which has never been reported in the previous literature. In addition, turbulent flow computations for T-junction flow are performed using the SST k-ω and Wray-Agarwal turbulence models. Finally, the influence of stenosis in Y-junction is studied and analyzed. The results have implications in understanding the hemodynamic flows in arterial bifurcations without and with stenosis.

CFD Simulation of Jet Mixing With Asymmetric Co-Flows in a Down-Scaled Rotary Kiln Model

2016 ◽  
Author(s):  
Ziyan Teng ◽  
Simon P. A. Johansson ◽  
I. A. Sofia Larsson ◽  
T. Staffan Lundström ◽  
B. Daniel Marjavaara
Keyword(s):  
Cfd Simulation ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Spreading Rate ◽  
Jet Mixing ◽  
Back Plate ◽  
Strongly Connected ◽  
Rotary Kilns ◽  
Secondary Air ◽  
Air Channels

Rotary kilns used in the iron pellet production in the grate-kiln pelletizing process normally have two asymmetric secondary air channels. The primary jet is ejected from a burner located in the middle of a back plate. As a consequence of the high flow rates and irregular-shaped secondary air channels, the aerodynamics in the kiln is strongly connected to the combustion and sintering performance. In this work a Computational Fluid Dynamics study is performed on a downscaled, simplified kiln model established in earlier numerical and experimental work. Comparisons are made with the experiment and among three turbulence models, the standard k-ε model, a k-ε model modified for turbulent axisymmetric round jets and Speziale-Sarkar-Garski Reynolds Stress Model (SSG-RSM hereafter). Recirculation regions with negative axial velocity are found at the upper side of the kiln and behind the back plate. Results from the standard k-ε model have the best fit to the experimental data regarding the centerline decay and the jet spreading of the velocity. The spreading rate of the scalar concentration calculated from the results with the modified k-ε model and the SSG-RSM fit better with the experiment, but they both underestimate the centerline decay and the spreading of the velocity. The modified k-ε model yields a more physical and realistic flow field compared to the standard k-ε model, and the results are close to those obtained with the SSG-RSM. Unlike the isotropic development of the jet predicted with the standard k-ε model, the modified k-ε model and the SSG-RSM show different development of the jet in the horizontal and vertical directions.

Sign in / Sign up

Export Citation Format

Share Document