scholarly journals Experimental Study and Hydrodynamic Modelling of the Wet Agglomeration Process

2018 ◽  
Author(s):  
Benjamin Oyegbile ◽  
Guven Akdogan ◽  
Mohsen Karimi
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Flow Analysis ◽  
Outer Region ◽  
Tangential Velocity ◽  
Numerical Code ◽  
Cfd Model ◽  
Rotating Disc ◽  
Batch Mode ◽  
Agglomeration Process

In this study, an experimentally validated computational model was developed to investigate the hydrodynamics in a rotor-stator vortex RVR agglomeration reactor having a rotating disc at the centre with two shrouded outer plates. A numerical simulation was performed using a simplified form of the reactor geometry to compute the 3D flow field in batch mode operations. Thereafter, the model was validated using data from a 2D Particle Image Velocimetry (PIV) flow analysis performed during the design of the reactor. Using different operating speeds—70, 90, 110 and 130 rpm, the flow fields were computed numerically followed by a comprehensive data analysis. The simulation results showed separated boundary layers on the rotating disc and the stator. The flow field within the reactor is characterized by a rotational plane circular forced vortex flow in which the streamlines are concentric circles with a rotational vortex. Overall, the results of the numerical simulation demonstrate a fairly good agreement between the CFD model and the experimental data as well as the available theoretical predictions. The swirl ratio β was found to be approximately 0.4044, 0.4038, 0.4044 and 0.4043 for operating speeds of N=70, 90, 110 and 130 rpm respectively. In terms of the spatial distribution, the turbulence intensity and kinetic energy are concentrated on the outer region of the reactor while the axial velocity showed a decreasing intensity towards the shroud. However, a comparison of the CFD and experimental predictions of the tangential velocity and the vorticity amplitude profiles shows that these parameters were under-predicted by the experimental analysis which could be attributed to some of the experimental limitations rather than the robustness of the CFD model or numerical code.

scholarly journals Experimental and CFD Studies of the Hydrodynamics in Wet Agglomeration Process

2018 ◽  
Vol 2 (3) ◽  
pp. 32 ◽  
Author(s):  
Benjamin Oyegbile ◽  
Guven Akdogan ◽  
Mohsen Karimi
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Flow Analysis ◽  
Outer Region ◽  
Tangential Velocity ◽  
Numerical Code ◽  
Cfd Model ◽  
Rotating Disc ◽  
Batch Mode ◽  
Agglomeration Process

In this study, an experimentally validated computational model was developed to investigate the hydrodynamics in a rotor-stator vortex agglomeration reactor RVR having a rotating disc at the centre with two shrouded outer plates. A numerical simulation was performed using a simplified form of the reactor geometry to compute the 3-D flow field in batch mode operations. Thereafter, the model was validated using data from a 2-D Particle Image Velocimetry (PIV) flow analysis performed during the design of the reactor. Using different operating speeds, namely 70, 90, 110, and 130 rpm, the flow fields were computed numerically, followed by a comprehensive data analysis. The simulation results showed separated boundary layers on the rotating disc and the stator. The flow field within the reactor was characterized by a rotational plane circular forced vortex flow, in which the streamlines are concentric circles with a rotational vortex. Overall, the results of the numerical simulation demonstrated a fairly good agreement between the Computational Fluid Dynamics (CFD) model and the experimental data, as well as the available theoretical predictions. The swirl ratio β was found to be approximately 0.4044, 0.4038, 0.4044, and 0.4043 for the operating speeds of N = 70, 90, 110, and 130 rpm, respectively. In terms of the spatial distribution, the turbulence intensity and kinetic energy were concentrated on the outer region of the reactor, while the circumferential velocity showed a decreasing intensity towards the shroud. However, a comparison of the CFD and experimental predictions of the tangential velocity and the vorticity amplitude profiles showed that these parameters were under-predicted by the experimental analysis, which could be attributed to some of the experimental limitations rather than the robustness of the CFD model or numerical code.

Numerical Simulation on the Electrophoretic Motion of Multiple Particles in Microchannels

2004 ◽  
Author(s):  
Chunzhen Ye ◽  
Dongqing Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Electric Field ◽  
Particle Motion ◽  
Outer Region ◽  
Numerical Results ◽  
The Other ◽  
Double Layers ◽  
Rectangular Microchannel ◽  
Moving Particle

This paper considers the electrophoretic motion of multiple spheres in an aqueous electrolyte solution in a straight rectangular microchannel, where the size of the channel is close to that of the particles. This is a complicated 3-D transient process where the electric field, the flow field and the particle motion are coupled together. The objective is to numerically investigate how one particle influences the electric field and the flow field surrounding the other particle and the particle moving velocity. It is also aimed to investigate and demonstrate that the effects of particle size and electrokinetic properties on particle moving velocity. Under the assumption of thin electrical double layers, the electroosmotic flow velocity is used to describe the flow in the inner region. The model governing the electric field and the flow field in the outer region and the particle motion is developed. A direct numerical simulation method using the finite element method is adopted to solve the model. The numerical results show that the presence of one particle influences the electric field and the flow field adjacent to the other particle and the particle motion, and that this influences weaken when the separation distance becomes bigger. The particle motion is dependent on its size, with the smaller particle moving a little faster. In addition, the zeta potential of particle has an effective influence on the particle motion. For a faster particle moving from behind a slower one, numerical results show that the faster moving particle will climb and then pass the slower moving particle then two particles’ centers are not located on a line parallel to the electric field.

scholarly journals RESEARCH ON NUMERICAL SIMULATION FOR VELOCITY DISTRIBUTION OF SWIRLING TURBULENT JETS IN SPRAY IRRIGATION TECHNOLOGY

2010 ◽  
Vol 13 (2) ◽  
pp. 93-99
Author(s):  
Tuyen Vo ◽  
Nam Thanh Nguyen
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Tangential Velocity ◽  
Turbulent Jets ◽  
Intensity Coefficient ◽  
Irrigation Technology ◽  
Swirl Intensity ◽  
Intensity Changes ◽  
Basic Parameters ◽  
Spray Irrigation

In spray irrigation technology, the change of the basic parameters of the flowfteld has relationship directly with the coefficient of swirling intensity coefficient s, with each value of swirling coefficient differently then the distribution of parameters in flow field also variedly. Remarkably change when the coefficient of swirl intensity changes through the variables as axial velocity u, tangential velocity w; the change of radial velocity V related to turbulent intensity.

Numerical Simulation of Flow Field in Bloom Continuous Casting Mold with Electromagnetic Stirring

2010 ◽  
Vol 146-147 ◽  
pp. 272-276 ◽  
Author(s):  
Jing Zhang ◽  
En Gang Wang ◽  
An Yuan Deng ◽  
Xiu Jie Xu ◽  
Ji Cheng He
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Flow Field ◽  
Continuous Casting ◽  
Tangential Velocity ◽  
Electromagnetic Stirring ◽  
Continuous Casting Mold ◽  
Frequency Increase ◽  
Velocity Increase ◽  
Casting Mold

A coupled numerical simulation of magnetic field and flow field was conducted basing on Φ250mm bloom during continuous casting with electromagnetic stirring.The distribution of the flow field was analyzed in different current and frequency.At the same current,the velocity first decrease and then increase as the frequency increase along the casting direction.At the same frequency, tangential velocity is dominant in the radial of EMS center,velocity increase with the current. Considered the results of numerical simulation,the optimized EMS parameters of Φ250mm bloom are the stirring current of 480A and the stirring frequency of 3Hz.

Numerical Simulation on Transient Electrophoretic Motion of a Circular Particle in a T-Shaped Slit Microchannel

2003 ◽  
Author(s):  
Chunzhen Ye ◽  
Dongqing Li
Keyword(s):  
Numerical Simulation ◽  
Liquid Phase ◽  
Flow Field ◽  
Electric Field ◽  
Particle Motion ◽  
Outer Region ◽  
Double Layers ◽  
Circular Particle ◽  
Electric Potentials ◽  
Inner Region

This paper considers the electrophoretic motion of a circular particle in a T-shaped slit microchannel, where the size of the channel is close to that of the particle. During the process, the electric field (i.e., the gradient of the electric potential) changes with the particle motion, which in return influences the flow field and the particle motion. Therefore, the electric field, the flow field and the particle motion are coupled together, and this is an unsteady process. The objective is to obtain a fundamental understanding of the characteristics of the particle motion in the complicated T-shaped junction region. Such influences on the electric field and the particle motion are investigated as the applied electric potentials, the geometry of the channel and the size of the particle. In the theoretical analysis, the liquid phase is divided into the inner region and the outer region. The inner region consists of the electrical double layers and the outer region consists of the remainder of the liquid. Under the assumption of thin electrical double layer, a mathematical model governing the inner region, the outer region and the particle motion is developed. A direct numerical simulation method using the finite element method is employed. In this method, a continuous hydrodynamic model is adopted. By this model, both the liquid phase in the outer region and the particle phase are governed by the same momentum equations. ALE method is used to track the surface of the particle at each time step. The numerical results show that the electric field is influenced by the applied electric potentials, the geometry of the channel and the particle suspension, and that the particle motion is mainly dominated by the local electric field. It is also found that the magnitude of the particle motion is dependent on its own size in the same channel.

Study on Flow Field Character Around Bypass Crossover Sub in Fracturing Process of Horizontal Wells

2009 ◽  
Author(s):  
Zunce Wang ◽  
Yan Xu ◽  
Sen Li ◽  
Fengxia Lv ◽  
Wei Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Reverse Flow ◽  
Tangential Velocity ◽  
Horizontal Wells ◽  
Computational Method ◽  
Wall Area ◽  
Fracturing Process ◽  
Breadth Ratio ◽  
The Impact

Based on Reynolds Stress Model (RSM), numerical simulation of flow field around Bypass Crossover Sub in the fracturing process of horizontal wells is carried out by Computational Fluid Dynamics (CFD) analysis. Distribution rules of axial velocity, tangential velocity and radial velocity of fluid field in calculation region are achieved. Results show that strong vortexes and reverse flow exist at the slots on Bypass Crossover Sub, which brings the impact of the fluid on the wall at certain angle. Impacting velocity and angle at different positions of the wall are studied in detail. A Laser Doppler Anemometer (LDA) is applied to examine the flow field velocity distribution. Experimental results agree well with the numerical simulation results, which prove the validity of turbulence model and computational method. Numerical simulation is carried out at different Length-Breadth ratio of slots on the Bypass Crossover Sub. Effect of the Length-Breadth ratio on the scale of vortexes, speed distributions and flow field near the wall area is discussed. All of these will provide some reference on structural optimization and the analysis of erosion.

Recommendations for Achieving Accurate Numerical Simulation of Tip Clearance Flows in Transonic Compressor Rotors

1999 ◽  
Vol 122 (4) ◽  
pp. 733-742 ◽  
Author(s):  
Dale E. Van Zante ◽  
Anthony J. Strazisar ◽  
Jerry R. Wood ◽  
Michael D. Hathaway ◽  
Theodore H. Okiishi
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Shear Layer ◽  
Tip Clearance ◽  
Numerical Code ◽  
Laser Doppler Velocimeter ◽  
Simple Method ◽  
Tip Clearance Flow ◽  
Transonic Compressor ◽  
Clearance Flow

The tip clearance flows of transonic compressor rotors are important because they have a significant impact on rotor and stage performance. A wall-bounded shear layer formed by the relative motion between the overtip leakage flow and the shroud wall is found to have a major influence on the development of the tip clearance flow field. This shear layer, which has not been recognized by earlier investigators, impacts the stable operating range of the rotor. Simulation accuracy is dependent on the ability of the numerical code to resolve this layer. While numerical simulations of these flows are quite sophisticated, they are seldom verified through rigorous comparisons of numerical and measured data because these kinds of measurements are rare in the detail necessary to be useful in high-speed machines. In this paper we compare measured tip-clearance flow details (e.g., trajectory and radial extent) with corresponding data obtained from a numerical simulation. Laser-Doppler Velocimeter (LDV) measurements acquired in a transonic compressor rotor, NASA Rotor 35, are used. The tip clearance flow field of this transonic rotor is simulated using a Navier–Stokes turbomachinery solver that incorporates an advanced k–ε turbulence model derived for flows that are not in local equilibrium. A simple method is presented for determining when the wall-bounded shear layer is an important component of the tip clearance flow field. [S0889-504X(00)02504-6]

Three-dimensional numerical simulation of air flow and fiber dynamic in carding region in carding machine

2019 ◽  
Vol 89 (19-20) ◽  
pp. 3916-3926
Author(s):  
Shanshan He ◽  
Longdi Cheng ◽  
Wenliang Xue ◽  
Zhong Lu ◽  
Liguo Chen
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Finite Element ◽  
Flow Field ◽  
Axial Velocity ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Element Model ◽  
Mechanical Analysis ◽  
Field Simulation

Regular cylinder metallic card clothing has a limited carding efficiency. As a result of the limited dimensions, any measurement between the cylinder and flat area is difficult to make. In this study, an approach is first proposed to simulate the flow field and a fiber finite-element model on the moving surface of the teeth and produce a new design of misaligned-teeth card clothing, with the aim of improving the carding efficiency. A comparison is made between regular and misaligned-teeth card clothing types with respect to flow field simulation and fiber mechanical properties. The results show that the force resulting from the tangential velocity between the cylinder and flat is as great as 1.86 × 10−3 N, sufficient to pull fiber out of tufts, and that the tangential velocity (from 3880 to 2500 mm/s) plays a major role in this area, as opposed to the axial velocity (from 0 to 190 mm/s). Through this comparison, the misalignment design can result in a different tangential velocity distribution from that of traditional card clothing, which helps fibers between two lines of teeth move into neighboring lines of teeth, thereby increasing the likelihood that fibers will be carded. For fiber mechanical analysis, different air forces are loaded on fibers. This comparison shows that for fibers in the channel, the misalignment can help fibers move toward the teeth. Therefore, this misaligned-teeth card clothing is thought to prove more effective in practice.

Numerical simulation of the flow field in a bioreactor

2000 ◽  
Vol 41 (4-5) ◽  
pp. 207-210 ◽  
Author(s):  
S. Ester ◽  
X. Guo ◽  
A. Delgado
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Numerical Method ◽  
Mechanical Behaviour ◽  
Numerical Code ◽  
Measurement Instruments ◽  
Local Flow ◽  
Velocity Pressure ◽  
Detailed Picture ◽  
Good Agreement

In order to give detailed information about the local flow field in a bioreactor a numerical method has been developed. This method gives information about the velocity, pressure and temperature in each point of the reactor, avoiding the problems caused by placing measurement instruments inside. Comparisons of experiments and numerical results show good agreement. The functionality and physical fundamentals of this tool are described. This is followed by explaining a reasonable application of the numerical code in the field of biological reactors. The reactors considered are filled with polydisperse, spherical support particles. From the results of the simulation a detailed picture of a reactor's fluid mechanical behaviour is drawn. This includes the quantification of mechanical stresses on the biofilm surface as well as information about the inflow, outflow and channelling behaviour of a reactor. Furthermore the effect of polydisperse support carries in discussed.

Analyses on Effect of Helix Angle on the Continuous Helical Baffles Heat Exchanger

2014 ◽  
Vol 1008-1009 ◽  
pp. 901-905
Author(s):  
Jia Zhu Zou ◽  
Feng Wei Yuan ◽  
Liang Bin Hu
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Exchanger ◽  
Cross Section ◽  
Outer Region ◽  
Tangential Velocity ◽  
Helix Angle ◽  
Heat Transfer Characteristics ◽  
Shell Side ◽  
Inner Region

A numerical simulation for heat exchanger with continuous helical baffles was carried out. The study focuses on the effects of helix angle on heat transfer characteristics. The results show that both the shell-side heat transfer coefficient and pressure drop decrease with the increase of the helix angle at certain mass flow rate. The latter decreases more quickly than the former. The tangential velocity distribution on shell-side cross section is more uniform with continuous helical baffles than with segmental baffles. The axial velocity at certain radial position decreases as the helix angle increases in the inner region near the central dummy tube, whereas it increases as the helix angle increases in the outer region near the shell. The heat exchange quantity distribution in tubes at different radial positions is more uniform at larger helix angel.

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