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.

CFD Investigation of a Fluidic Device for Modulation of Aero-Engine Cooling Air

2014 ◽  
Author(s):  
Bharat Koli ◽  
John W. Chew ◽  
Nick J. Hills ◽  
Timothy Scanlon
Keyword(s):  
Numerical Study ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Engine Cooling ◽  
Fluidic Device ◽  
Significant Performance ◽  
Secondary Air ◽  
Switching Characteristics ◽  
Engine Components ◽  
Cooling Air

The quantity of cooling air delivered by the secondary air system to various engine components is usually fixed by cooling requirements at the most arduous operating condition in the flight cycle. Modulation of cooling air would allow optimization of cooling supply at different flight cycle conditions, giving significant performance benefits. Switched vortex valves (SVV) have been proposed for control of air systems [1]. An important characteristics of this device is the absence of any moving part. This offers advantages compared to other systems. This report discusses the numerical study of a typical SVV. The study includes comparison of predicted results with available experimental data and prediction of switching characteristics of the device. In this study two turbulence models namely the Spalart-Allmaras model (SA) and Reynolds stress model (RSM) were used. The RSM showed a good agreement with measured mass flow rate and qualitative agreement with other experimental observations.

scholarly journals A suitable k-epsilon model for CFD simulation of pump-around jet mixing tank with moderate jet reynolds number

2018 ◽  
Vol 192 ◽  
pp. 03010 ◽  
Author(s):  
Satapan Phapatarinan ◽  
Eakarach Bumrungthaichaichan ◽  
Santi Wattananusorn
Keyword(s):  
Reynolds Number ◽  
Numerical Methods ◽  
Cfd Simulation ◽  
Mixing Time ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Suitable Model ◽  
Mixing Times ◽  
Jet Mixing ◽  
Low Reynolds

This paper presents the appropriate turbulence model for predicting the overall mixing time inside an open 45° inclined side entry pump-around jet mixing tank with moderate jet Reynolds number of about 17,515. The model was carefully developed by using appropriate hexahedral grid arrangement and proper numerical methods. The two different k-epsilon turbulence models, including realizable k-epsilon model and low Reynolds number k-epsilon model, were simulated. The overall mixing times predicted by these turbulence models were compared with the previous data reported by Patwardhan (Chem. Eng. Sci. 57 (2002) 1307-1318). The results revealed that the low Reynolds number k-epsilon model was a suitable model for predicting the overall mixing time of jet mixing tank with moderate jet Reynolds number.

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.

CFD and Experiment Investigation of the Mixing Characteristics of Non-Newtonian Fluids in a Stirred Vessel

2018 ◽  
Author(s):  
Peng Wang ◽  
Thomas Reviol ◽  
Haikun Ren ◽  
Martin Böhle
Keyword(s):  
Reynolds Stress ◽  
Newtonian Fluid ◽  
Cfd Simulation ◽  
Rotation Speed ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Operating Conditions ◽  
Newtonian Fluids ◽  
Stress Model ◽  
Stirred Vessel

The mixing performance of a novel design propeller fixed at a position with the angle of −10° combine the inference of the variety of rotation speed and rheology properties were investigated using an ultrasonic Doppler anemometer (UDA) and CFD simulation to investigate the flow patterns and the power consumption in a mixing vessel. The fluids of interest in this research are CMC fluids, which is a type of Walocel CRT 40,000PA powder was added into water to prepare the solutions with the mass concentration which performed shear thinning non-Newtonian fluid properties. As the viscosity of the non-Newtonian fluids varies from the shear rate, rather than a constant value. Therefore, a non-Newtonian power-law model has been selected to describe the properties of the non-Newtonian fluids, and combine with six turbulence models (the standard k-ω model, RNG k-ε, standard k-ε, Realizable k-ε, SST k-ω and Reynolds stress model (RSM))for mechanical agitation of non-Newtonian fluids. Through comparing experiment results, the SST k-ω and Reynolds stress model (RSM) are found more physical than other turbulence models at the design operating point. Furthermore, the CFD simulation results from Reynolds stress model (RSM) and the SST models were validated with the experimental results over the range of rotation speed (small, design, and large rotation speeds), and show that the simulated propeller torque and flow patterns agreed very well with experimental measurements. The velocity field distribution with different operating conditions within selected planes also have been compared with each other and found that for different rheology concentrations and operating conditions, the turbulence model should be properly chosen. The model for simulating non-Newtonian fluid in a stirred vessel in this study can lay a foundation for further optimum research.

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.

A comparison of the experimental and computational modelling of the fluidic turn-up vortex amplifier at full and zero swirl conditions

2001 ◽  
Vol 215 (8) ◽  
pp. 893-903 ◽  
Author(s):  
R. J. Woolhouse ◽  
J. R. Tippetts ◽  
S. B. M. Beck
Keyword(s):  
Cfd Simulation ◽  
Computational Modelling ◽  
Turbulence Models ◽  
Ambient Air ◽  
Reynolds Stress Model ◽  
Time Dependent ◽  
Uniform Density ◽  
Gaseous Fuels ◽  
Dependent Flow ◽  
And Performance

The design and operation of a novel type of fluidic vortex amplifier have been investigated experimentally using model tests with ambient air, and using computationally time-dependent computational fluid dynamics (CFD) simulation. The ultimate objective is to develop a no-moving-part variable air distribution device for implementation within gas turbine combustors using the fuel flow as the controlling agent. Although both liquid and gaseous fuels are ultimate goals of this device, this paper describes the first stage of the work involving operation with nominally uniform density fluid (air). There is some discrepancy between the simulation and test data, but design and performance trends were usefully simulated. An important feature of the CFD was the occurrence of a weak time dependent flow structure, particularly with the Reynolds stress model (RSM). Flow modulation within the desired range (4.5 compared with 2.6) was demonstrated, and these are shown, along with some general points concerning computational modelling convergence and turbulence models.

scholarly journals Numerical Analysis of Flow across Brush Elements Based on a 2-D Staggered Tube Banks Model

Aerospace ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 19
Author(s):  
Xiaolei Song ◽  
Meihong Liu ◽  
Xiangping Hu ◽  
Xueliang Wang ◽  
Taohong Liao ◽  
...  
Keyword(s):  
Euler Number ◽  
Dynamic Pressure ◽  
Labyrinth Seals ◽  
System A ◽  
Brush Seal ◽  
Back Plate ◽  
Computational Fluid Dynamics Cfd ◽  
Secondary Air ◽  
Tube Banks ◽  
Gas Expansion

In order to improve efficiency in turbomachinery, brush seal replaces labyrinth seals widely in the secondary air system. A 2-d staggered tube bank model is adopted to simulate the gas states and the pressure character in brush seal, and computational fluid dynamics (CFD) is used to solve the model in this paper. According to the simulation results, the corrected formula of the Euler number and dimensionless pressure are given. The results show that gas expands when flow through the bristle pack, and the gas expansion closes to an isotherm process. The dynamic pressure increases with decreasing static pressure. The Euler number can reflect the seal performance of brush seals in leakage characteristics. Compared with increasing the number of rows, the reduction of the gap is a higher-efficiency method to increase the Euler number. The Euler number continually increases as the gap decreases. However, with the differential pressure increasing, Euler number first increases and then decreases as the number of rows increases. Finally, the pressure distribution on the surface of end rows is asymmetric, and it may increase the friction between the bristles and the back plate.

Numerical Simulation of Depleted EAF Jet Flow

2013 ◽  
Vol 444-445 ◽  
pp. 1113-1117
Author(s):  
Chong Wang ◽  
Dao Fei Zhu ◽  
Fan Han Liu ◽  
Shi Bo Wang ◽  
Hua Wang
Keyword(s):  
Cfd Simulation ◽  
Theoretical Foundation ◽  
Slag Layer ◽  
Furnace Operation ◽  
Copper Industry ◽  
Oil Consumption ◽  
Rate Reduction ◽  
Insertion Depth ◽  
Jet Mixing ◽  
Slag Cleaning

In view of the serious problems that low-rate reduction and excessive oil consumption of reducing oil guns which are used in the depleted EAF, analyzing the jet mixing process through the CFD simulation with the method of liquid level tracking, we find that the purpose of mixing slag layer, guaranteeing matte layer precipitation and saving oil can be achieved by changing combination of gas rate of mixture injected by the oil gun, jet speed and insertion depth. The results of this paper provide a theoretical foundation for optimizing reducing technical process of the slag cleaning furnace operation in a copper industry Company.

scholarly journals Computational Modeling of Flow Characteristics in Three Products Hydrocyclone Screen

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1295
Author(s):  
Anghong Yu ◽  
Chuanzhen Wang ◽  
Haizeng Liu ◽  
Md. Shakhaoath Khan
Keyword(s):  
Static Pressure ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Flow Characteristics ◽  
Pressure Profile ◽  
Reynolds Stress Model ◽  
Grid Scheme ◽  
Cylindrical Screen ◽  
The Right ◽  
Axial Depth

Three products hydrocyclone screen (TPHS) can be considered as the combination of a conventional hydrocyclone and a cylindrical screen. In this device, particles are separated based on size under the centrifugal classification coupling screening effect. The objective of this work is to explore the characteristics of fluid flow in TPHS using the computational fluid dynamics (CFD) simulation. The 2 million grid scheme, volume fraction model, and linear pressure–strain Reynolds stress model were utilized to generate the economical grid-independence solution. The pressure profile reveals that the distribution of static pressure was axisymmetric, and its value was reduced with the increasing axial depth. The maximum and minimum were located near the tangential inflection point of the feed inlet and the outlets, respectively. However, local asymmetry was created by the left tangential inlet and the right screen underflow outlet. Furthermore, at the same axial height, the static pressure gradually decreased along the wall to the center. Near the cylindrical screen, the pressure difference between the inside and the outside cylindrical screen dropped from positive to negative as the axial depth increased from −35 to −185 mm. Besides, TPHS shows similar distributions of turbulence intensity I, turbulence kinetic energy k, and turbulence dissipation rate ε; i.e., the values fell with the decrease in axial height. Meanwhile, from high to low, the pressure values are distributed in the feed chamber, the cylindrical screen, and conical vessel; the value inside the screen was higher than the outer value.

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