Mixture of Particles' Influence in Computer Simulations of a Spouted Bed

2010 ◽  
Vol 660-661 ◽  
pp. 448-453 ◽  
Author(s):  
D.A. Santos ◽  
I. Petri Junior ◽  
Marcos A.S. Barrozo ◽  
Claudio Roberto Duarte
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Fluid Dynamic ◽  
Computational Simulation ◽  
Particle Interaction ◽  
Multiphase Model ◽  
Spouted Bed ◽  
Air Concentration ◽  
Spouted Beds ◽  
Full Plane

This article aims to assess the influence of the way of simulating monoparticles as just monoparticles or as a mixture of particles, the latter, unlike the first, considering the effect of particle-particle interaction. The Eulerian–Eulerian multiphase model is used in the computational simulation of fluid dynamics of spouted beds and compared with experimental data. A half column of cylindrical spouted bed with a full plane glass attached to the front open surface of the bed as the transparent window was used for observation and photographing. Images of solid flows were recorded using a high speed camera (2000 frames per second). Glass beads with a diameter of 0.00368, 0.005 and 0.00252 mm are used as bed material. The simulated characteristic fluid dynamic curves of spouted bed for 0.15 m static bed heights (Ho) were obtained with good agreement with experimental data when the monoparticles was simulated as a mixture of particles with mixture’s percentage of 50%. The same occurred for the simulation of vertical velocities of particles profile, that is, when the monoparticles was simulated as a mixture of particles with mixture’s percentage of 50% we observed a more approach to the experimental data. It was also observed that the air concentration distribution seem to be independent of the changing of the composition.

Identification of the Spouted Bed Flow Regime by Simulation and Experimental Data

2008 ◽  
Vol 591-593 ◽  
pp. 329-334 ◽  
Author(s):  
R.O. Lourenço ◽  
Kássia Graciele dos Santos ◽  
Valéria V. Murata ◽  
Claudio Roberto Duarte ◽  
Humberto Molinar Henrique ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Flow Regimes ◽  
Visual Observation ◽  
Circulation Rate ◽  
Multiphase Model ◽  
Spouted Bed ◽  
Spouted Beds ◽  
Experimental Apparatus

The particle circulation rate and gas–solid contacting efficiency are important parameters for the project of spouted beds, applied in many industrial processes. Due to the restrictions found in the identification of flow regimes through visual observation, new techniques have been developed to obtain a better gas and particle dynamics description, necessary for the evaluation of these parameters. One of these techniques has been the CFD simulation. In this work the pattern of solids and gas flows in a spouted bed was numerically simulated using a 3D Eulerian multiphase model. Soybean particles had been used in the attainment of data of pressure drop fluctuation and power spectrum as a function of gas velocity in an experimental apparatus. The 3D simulated solids volume fraction profiles allow the identification of the flow regimes showing a good agreement with the experimental data.

Study of Measurement Methods of Particle Velocity in a Spouted Bed

2012 ◽  
Vol 727-728 ◽  
pp. 1842-1847
Author(s):  
D.A. Santos ◽  
G.C. Alves ◽  
M.A.S. Barrozo ◽  
Claudio Roberto Duarte
Keyword(s):  
Particle Velocity ◽  
High Speed ◽  
Measurement Techniques ◽  
Video Camera ◽  
Three Dimensions ◽  
Average Particle ◽  
Multiphase Model ◽  
Spouted Bed ◽  
Spouted Beds ◽  
Fiber Optical

Average particle velocity measurements were carried out in a conical-cylindrical spouted bed made of acrylic. In this study an intrusive fiber optical technique which is based on a cross-correlation function between signals from its two channels was used. For a non-intrusive measurement in order to compare with the intrusive technique, images of particle movement were recorded using a high-speed video camera. The experiments were conducted in differents air velocity conditions above the minimum spouting velocity. The latter method was limited in velocity measurement only near the spouted beds wall inasmuch as the spouted bed used was a three dimensions one. On the other hand, the fiber optical is a promising technique for measuring particle velocity distributions in a three dimensions spouted bed. To predict the minimum spouting velocity in order to use this result in the measurement techniques investigation, simulations were carried out using the Eulerian-Eulerian multiphase model.

Simulation of Spouted Bed Using a Eulerian Multiphase Model

2005 ◽  
Vol 498-499 ◽  
pp. 270-277 ◽  
Author(s):  
Claudio Roberto Duarte ◽  
Valéria V. Murata ◽  
Marcos A.S. Barrozo
Keyword(s):  
Control Volume ◽  
Flow Behavior ◽  
Cfd Modeling ◽  
Gas Flows ◽  
Present Calculation ◽  
Multiphase Model ◽  
Spouted Bed ◽  
Particle Coating ◽  
Spouted Beds ◽  
Good Agreement

Spouted bed systems have emerged as very efficient fluid-particle contactors and find many applications in the chemical and biochemical industry. Some important applications of spouted beds include coal combustion, biochemical reactions, drying of solids, drying of solutions and suspensions, granulation, blending, grinding, and particle coating. An extensive overview can be found in Mathur and Epstein[1]. The pattern of solid and gas flows in a spouted bed was numerically simulated using a CFD modeling technique. The Eulerian-Eulerian multifluid modeling approach was applied to predict gas-solid flow behavior. A commercially available, control-volume-based code FLUENT 6.1 was chosen to carry out the computer simulations. In order to reduce computational times and required system resources, the 2D axisymmetric segregated solver was chosen. The typical flow pattern of the spouted bed was obtained in the present calculation. The simulated velocity and voidage profiles presented a good agreement qualitative and quantitative with the experimental results obtained by He et al. [4].

Numerical and Experimental Study of Multiphase Transient Core-Annular Flow Patterns in a Spouted Bed

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Ling Zhou ◽  
Chen Han ◽  
Ling Bai ◽  
Weidong Shi ◽  
Ramesh Agarwal
Keyword(s):  
Numerical Simulations ◽  
Flow Pattern ◽  
High Speed ◽  
Annular Flow ◽  
Fluid Phase ◽  
Flow Patterns ◽  
Spouted Bed ◽  
High Speed Imaging ◽  
Spouted Beds ◽  
Number Of Particles

Abstract Dense solid–gas bubbling systems with combined fluid-particle motion are among one of the most extensively used fluidization forms used in the chemical industry. Therefore, it is important to have a good understanding of the hydrodynamic behavior of bubbles. In this paper, both the experiment and numerical simulations are used to investigate the flow patterns in a spouted bed. For numerical simulations, the bidirectional coupling simulations using computational fluid dynamics (CFD) with discrete element method (DEM) are conducted. The results show that the simulations can accurately predict the bubbles morphology compared with the experimental results. When the number of particles is 30,000, only a single core-annular flow pattern appears. When the number of particles is increased to 36,500, the single bubble in the spouted bed transitions into two and a double core-annular flow pattern emerges. As the number of particles is increased to 43,000, a complex multicore-annular flow pattern appears. These flow patterns are also observed in the experiments using high-speed imaging camera. This paper analyzes and explains the causes of these flow phenomena from the dynamic characteristics of particle phase and fluid phase. These results have great significance in providing guidance for optimization of dense phase bubbling spouted beds.

An Improved Particle Impact Model by Accounting for Rate of Strain and Stochastic Rebound

2018 ◽  
Author(s):  
Steven M. Whitaker ◽  
Jeffrey P. Bons
Keyword(s):  
Experimental Data ◽  
Yield Strength ◽  
High Speed ◽  
Computational Simulation ◽  
Particle Impact ◽  
Impact Model ◽  
Model Predictions ◽  
Effective Yield ◽  
Improved Model ◽  
Deposition Models

A methodology for informing physics-based impact and deposition models through the use of novel experimental and analysis techniques is presented. Coefficient of Restitution (CoR) data were obtained for Arizona Road Dust (ARD), AFRL02 dust, and each component of AFRL02 impacting a Hastelloy X plate at a variety of flow temperatures (295–866 K), surface temperatures (295–1255 K), particle velocities (0–100 m/s), and impact angles (0–90 degrees). High speed Particle Shadow Velocimetry (PSV) allowed individual impact data to be obtained for more than 8 million particles overall, corresponding to 20 combinations of particle composition, flow temperature, and surface temperature. The experimental data were applied to an existing physics-based particle impact model to assess its ability to accurately capture the physics of particle impact dynamics. Using the experimental data and model predictions, two improvements to the model were proposed. The first defined a velocity-dependent effective yield strength, designed to account for the effects of strain hardening and strain rate during impact. The second introduces statistical spread to the model output, accounting for the effect of randomizing variables such as particle shape and rotation. Both improvements were demonstrated to improve the model predictions significantly. Applying the improved model to the experimental data sets, along with known temperature-dependent material properties such as the elastic modulus and particle density, allowed the temperature dependence of the effective yield strength to be determined. It was found that the effective yield strength is not a function of temperature over the range studied, suggesting that changes in other properties are responsible for differences in rebound behavior. The improved model was incorporated into a computational simulation of an impinging flow to assess the effect of the model improvements on deposition predictions, with the improved model obtaining deposition trends that more closely match what has been observed in previous experiments. The work performed serves as a stepping stone towards further improvement of physics-based impact and deposition models through refinement of other modeled physical processes.

CFD Multifluid Simulation of Spouted Beds with and without Internal Draft Tubes

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Mahmood Reza Rahimi ◽  
Salar Azizi
Keyword(s):  
Experimental Data ◽  
Particle Trajectory ◽  
Draft Tube ◽  
Granular Flows ◽  
Spouted Bed ◽  
Drag Model ◽  
Spouted Beds ◽  
Particulate Solids ◽  
Computational Fluid Dynamics Cfd ◽  
Draft Tubes

The insertion of an axially positioned non-porous and porous draft tube into the conventional spouted bed has shown potential advantages in stability and flexibility of the system and controlling particle trajectory history. In this work with computational fluid dynamics (CFD), important information on the flow field within three types of spouted bed has been provided and influences of using internal tube on spouted beds hydrodynamics were investigated. The simulation used the multi-fluid Eulerian-Eulerian approach based on kinetic theory of granular flows (KTGF), incorporating a kinetic-frictional constitutive model for dense assemblies of particulate solids and Gidaspow’s drag model for the interaction between gas and particles. Finally, the modeling results were compared with the experimental data from literature.

An Investigation of the Different Flow Regimes in a Rotating Drum through Experimental and Simulation

2014 ◽  
Vol 802 ◽  
pp. 215-219
Author(s):  
D.A. Santos ◽  
Irineu Petri Jr. ◽  
C.R. Duarte ◽  
M.A.S. Barrozo
Keyword(s):  
Experimental Data ◽  
Particle Velocity ◽  
High Speed ◽  
Video Camera ◽  
Particle Dynamic ◽  
Multiphase Model ◽  
Rotating Drum ◽  
High Speed Video Camera ◽  
Simulation Results ◽  
Good Agreement

This paper aims to investigate the particle dynamic behavior in a rotating drum operating in a rolling regime under different rotating velocity, based on experimental results and simulations. Simple superphosphate fertilizer (SSP) was used as particulate matter in the current study. The Eulerian–Eulerian multiphase model along with the kinetic theory of granular flow was used in the simulations. In order to evaluate the simulation results, velocity distributions of the particulate phase were compared with experimental data. The experimental particle velocity distribution was obtained by using a high speed video camera. The numerical simulation results showed significant insights towards understanding of the particle dynamic in a rotating drum. The simulated results of particle velocity were in good agreement with the experimental data.

scholarly journals Experimental and Numerical Study of Water Entry Supercavity Influenced by Turbulent Drag-Reducing Additives

2014 ◽  
Vol 6 ◽  
pp. 280643 ◽  
Author(s):  
Chen-Xing Jiang ◽  
Feng-Chen Li
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
High Speed ◽  
Numerical Study ◽  
Ccd Camera ◽  
Water Entry ◽  
Multiphase Model ◽  
Turbulent Drag ◽  
Unsteady Rans ◽  
Simulation Results

The configurational and dynamic characteristics of water entry supercavities influenced by turbulent drag-reducing additives were studied through supercavitating projectile approach, experimentally and numerically. The projectile was projected vertically into water and aqueous solution of CTAC with weight concentrations of 100, 500, and 1000 ppm, respectively, using a pneumatic nail gun. The trajectories of the projectile and the supercavity configuration were recorded by a high-speed CCD camera. Besides, water entry supercavities in water and CTAC solution were numerically simulated based on unsteady RANS scheme, together with application of VOF multiphase model. The Cross viscosity model was adopted to represent the fluid property of CTAC solution. It was obtained that the numerical simulation results are in consistence with experimental data. Numerical and experimental results all show that the length and diameter of supercavity in drag-reducing solution are larger than those in water, and the drag coefficient is smaller than that in water; the maintaining time of supercavity is longer in solution as well. The surface tension plays an important role in maintaining the cavity. Turbulent drag-reducing additives have the potential in enhancement of supercavitation and drag reduction.

Development and Validation of a Three-Dimensional Multiphase Flow CFD Analysis for Journal Bearings in Steam and Heavy Duty Gas Turbines

2012 ◽  
Author(s):  
Stephan Uhkoetter ◽  
Stefan aus der Wiesche ◽  
Michael Kursch ◽  
Christian Beck
Keyword(s):  
Experimental Data ◽  
Multiphase Flow ◽  
Gas Turbines ◽  
High Speed ◽  
Three Dimensional ◽  
Air Entrainment ◽  
Journal Bearings ◽  
Heavy Duty ◽  
Present Contribution ◽  
Two Phase

The traditional method for hydrodynamic journal bearing analysis usually applies the lubrication theory based on the Reynolds equation and suitable empirical modifications to cover turbulence, heat transfer, and cavitation. In cases of complex bearing geometries for steam and heavy-duty gas turbines this approach has its obvious restrictions in regard to detail flow recirculation, mixing, mass balance, and filling level phenomena. These limitations could be circumvented by applying a computational fluid dynamics (CFD) approach resting closer to the fundamental physical laws. The present contribution reports about the state of the art of such a fully three-dimensional multiphase-flow CFD approach including cavitation and air entrainment for high-speed turbo-machinery journal bearings. It has been developed and validated using experimental data. Due to the high ambient shear rates in bearings, the multiphase-flow model for journal bearings requires substantial modifications in comparison to common two-phase flow simulations. Based on experimental data, it is found, that particular cavitation phenomena are essential for the understanding of steam and heavy-duty type gas turbine journal bearings.

scholarly journals Optical-Trapping Laser Techniques for Characterizing Airborne Aerosol Particles and Its Application in Chemical Aerosol Study

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 466
Author(s):  
Aimable Kalume ◽  
Chuji Wang ◽  
Yongle Pan
Keyword(s):  
Light Scattering ◽  
High Speed ◽  
Optical Trapping ◽  
Aerosol Particles ◽  
Particle Interaction ◽  
Raman Laser ◽  
General Description ◽  
Sample Collection ◽  
Laser Technologies ◽  
Laser Induced Breakdown

We present a broad assessment on the studies of optically-trapped single airborne aerosol particles, particularly chemical aerosol particles, using laser technologies. To date, extensive works have been conducted on ensembles of aerosols as well as on their analogous bulk samples, and a decent general description of airborne particles has been drawn and accepted. However, substantial discrepancies between observed and expected aerosols behavior have been reported. To fill this gap, single-particle investigation has proved to be a unique intersection leading to a clear representation of microproperties and size-dependent comportment affecting the overall aerosol behavior, under various environmental conditions. In order to achieve this objective, optical-trapping technologies allow holding and manipulating a single aerosol particle, while offering significant advantages such as contactless handling, free from sample collection and preparation, prevention of contamination, versatility to any type of aerosol, and flexibility to accommodation of various analytical systems. We review spectroscopic methods that are based on the light-particle interaction, including elastic light scattering, light absorption (cavity ring-down and photoacoustic spectroscopies), inelastic light scattering and emission (Raman, laser-induced breakdown, and laser-induced fluorescence spectroscopies), and digital holography. Laser technologies offer several benefits such as high speed, high selectivity, high accuracy, and the ability to perform in real-time, in situ. This review, in particular, discusses each method, highlights the advantages and limitations, early breakthroughs, and recent progresses that have contributed to a better understanding of single particles and particle ensembles in general.

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