scholarly journals Mechanism of the Absent Air Column in Three Products Hydrocyclone Screen (TPHS): Experiment and Simulation

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 431
Author(s):  
Chuanzhen Wang ◽  
Anghong Yu ◽  
Zaisheng Zhu ◽  
Haizeng Liu ◽  
Md. Shakhaoath Khan
Keyword(s):  
Static Pressure ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Particle Separation ◽  
Physical Experiment ◽  
High Definition ◽  
Static Pressure Distribution ◽  
Cylindrical Screen ◽  
Computational Fluid Dynamics Cfd ◽  
Air Column

Three products hyrdrocyclone screen (TPHS) has been proposed for particle separation based on size. In TPHS, a cylindrical screen was embedded in a conventional hydrocyclone (CH) to combine the centrifugal classification and screening to particle separation based on size. The industrial application of TPHS indicates its better device performance than CH. Although, the earlier studies reveal some common understanding for TPHS, the information of the absent air column remains unknown. Hence, the combination of physical experiment and numerical simulation was considered involving a 75 mm TPHS for this knowledge gap. First, both the computational fluid dynamics (CFD) simulation with Reynolds stress mode and the physical experiment with a high-definition camera illustrate the development process details of a flow field in TPHS. That is, the water was imported along the tangential inlet into TPHS; then under the effects of the feed chamber wall and gravity, the liquid phase spiraled downward until the cylindrical screen passed through the sieve; as the liquid moved to the spigot, it could be discharged in time due to the small underflow port, thus the volume fraction of air rapidly reduced from 1 to 0; subsequently the water filled the TPHS and the absent air column could be observed. Furthermore, the distribution comparisons of air volume fraction and static pressure show that TPHS displayed the absent air core with the negative static pressure in the center region along the z-axis, while CH displayed the opposite features. In addition, despite the different inlet velocity, TPHS consistently presented the vanished air column which could be ascribed to the fact that the present cylindrical screen resulted in positive static pressure distribution inside TPHS.

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.

scholarly journals Numerical Simulation of Breathing Mode Oscillation on Bubble Detachment

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 96
Author(s):  
Takao Oku ◽  
Hiroyuki Hirahara ◽  
Tomohiro Akimoto ◽  
Daiki Tsuchida
Keyword(s):  
Natural Frequency ◽  
Cfd Simulation ◽  
Low Frequency ◽  
Sound Emission ◽  
Breathing Mode ◽  
Bubble Deformation ◽  
Mode Oscillation ◽  
Computational Fluid Dynamics Cfd ◽  
Oscillation Frequencies ◽  
Air Column

When a bubble detaches from a nozzle immersed in water, a sound is emitted owing to the detachment. The bubble deformation and sound emission generated after detachment has been investigated in many studies, in which the breathing mode with a natural frequency was discussed based on the dynamics of the interface between the air and water. In this study, the deformation of a bubble was observed, and the sound emitted upon detachment was measured experimentally. To analyze the bubble deformation process, a computational fluid dynamics (CFD) simulation was conducted using the volume of fluid (VOF) method to predict the sound emission. In the analysis, the deformation behavior, the oscillation frequencies, sound pressure, and radius variation were discussed by comparing the numerical and experimental data. Furthermore, the natural frequency and low frequency vibrations were discussed based on the interference between the detached bubbles and the air column vibrations.

CFD Simulation of Segregation in Particulate Multiphase Flows With Binary Solids

2005 ◽  
Author(s):  
Zuoxin Hao
Keyword(s):  
Multiphase Flow ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Primary Objective ◽  
Cfd Simulations ◽  
Separation Processes ◽  
Solid Mixture ◽  
Computational Fluid Dynamics Cfd ◽  
Realistic Prediction

Segregation in particulate multiphase flow with binary solid mixture has extensive applications in industrial separation processes. Up to now there have been few attempts towards numerical simulation of segregation in particulate multiphase flow with binary mixture due to complexity of the problem. In view of this, the primary objective of present work is to simulate the problem by computational fluid dynamics (CFD) and to validate by comparison with experimental measurements. Eulerian-Eulerian approach, incorporating the granular temperature, an essential ingredient in the solids pressure and solids viscosity formulation, was used to model the flow field of multiphase flow and was solved by Fluent 6.0. The CFD simulation results have been validated by experiments of liquid fluidization of binary solid mixtures. Validation results show that CFD simulation predict segregation and solid volume fraction profile precisely, and in addition, it can supply a more realistic prediction of other hydrodynamic features of the multiphase flow, such as velocity vector of all phases and pressure drop. The success of such CFD simulations opens doors for many potential studies.

Influence of Jordanian zeolite on the performance of a solar still: experiments and CFD simulation studies

2016 ◽  
Vol 16 (6) ◽  
pp. 1700-1709 ◽  
Author(s):  
Yazan Taamneh
Keyword(s):  
Experimental Data ◽  
Phase Change ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Solar Still ◽  
Cfd Simulations ◽  
Two Phase ◽  
Vof Model ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Computational fluid dynamics (CFD) simulations were performed for experiments carried out with two identical pyramid-shaped solar stills. One was filled with Jordanian zeolite-seawater and the second was filled with seawater only. This work is focused on CFD analysis validation with experimental data conducted using a model of phase change interaction (evaporation-condensation model) inside the solar still. A volume-of-fluid (VOF) model was used to simulate the inter phase change through evaporation-condensation between zeolite-water and water vapor inside the two solar stills. The effect of the volume fraction of the zeolite particles (0 ≤ ϕ ≤ 0.05) on the heat and distillate yield inside the solar still was investigated. Based on the CFD simulation results, the hourly quantity of freshwater showed a good agreement with the corresponding experimental data. The present study has established the utility of using the VOF two phase flow model to provide a reasonable solution to the complicated inter phase mass transfer in a solar still.

A solution for transverse thermal conductivity of composites with quadratic or hexagonal unidirectional fibres

2014 ◽  
Vol 21 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Xueliang Xiao ◽  
Andrew Long
Keyword(s):  
Thermal Conductivity ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Thermal Contact ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Fluid Interface ◽  
Transverse Thermal Conductivity ◽  
Computational Fluid Dynamics Cfd ◽  
Unidirectional Fibre

AbstractA solution for the transverse thermal conductivity (Ke) of unidirectional fibre arrays, quadratic and hexagonal, is developed analytically. The solution integrates the thermal conductivity of fibre (Kf) and fluid (Km) based on electricity analogy without thermal contact resistance (Rc) at the fibre/fluid interface. The expression Ke is a function of Kf and Km, as well as of the fibre volume fraction (Vf). In this article, Ke values of four composites were predicted and verified by computational fluid dynamics (CFD) simulations. The results showed good agreement when the ratio of Kf/Km is close to 1. An increase in the ratio or Vf gives poorer agreement owing to the local temperature gradient at the fibre/fluid interface. CFD simulation also showed that Ke is decreasing as the Rc value increases.

scholarly journals Numerical investigation of the hydrocyclone vortex finder depth on separation efficiency

2021 ◽  
Vol 347 ◽  
pp. 00039
Author(s):  
Lesiba Mokonyama ◽  
Thokozani Justin Kunene ◽  
Lagouge Kwanda Tartibu
Keyword(s):  
Fluid Dynamics ◽  
Cfd Simulation ◽  
Fine Particles ◽  
Volume Fraction ◽  
Separation Efficiency ◽  
Cfd Simulations ◽  
Industrial Sectors ◽  
Air Core ◽  
Vortex Finder ◽  
Computational Fluid Dynamics Cfd

Hydrocyclones are devices used in numerous chemicals, food, and mineral-related industrial sectors for the separation of fine particles. A d50 mm hydrocyclone was modelled with the use of the Computational fluid dynamics (CFD) simulation, ANSYS® Fluent 2021 R1. The vortex finder depth was varied from 20 mm, 30 mm, and 35 mm to observe the effects of pressure drop and separation efficiency from a varied vortex finder depth and characteristics of the air core. The numerical methods validated the results observed from different parameters such as volume fraction characteristics based on CFD simulations. The tangential and axial velocities increased as the vortex finder length increased. It was found that as the depth of the vortex finder is increased, particle re-entrainment time in the underflow stream increases, and separation efficiency improved.

Effect of Intruded Exit on Riser Type Circulating Fluidized Beds

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
Sudarshan K. Daga ◽  
Vineet Kumar
Keyword(s):  
Granular Flow ◽  
Particle Distribution ◽  
Cfd Simulation ◽  
Circulating Fluidized Bed ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Circulating Fluidized Beds ◽  
Group A ◽  
Computational Fluid Dynamics Cfd ◽  
Group B

The present work attempts to study the flow dynamics of Geldart group A and group B particles in a circulating fluidized bed (CFB) riser with intruded exits using computational fluid dynamics (CFD) techniques. In this work, three different designs of riser exit geometries were studied using a 2D transient Eulerian approach with kinetic theory of granular flow in a commercial CFD simulation package. The three exits geometries, namely conventional exit, intruded curved and straight exits were designed and simulated. The various factors like solid volume fraction, pressure drop, and solid velocity were studied for both group A and group B particles. Results indicate that intruded exits have certain advantages like low riser pressure, uniform particle distribution, etc., over the conventional design because fluid and particle comes out from the core of the riser where there is no wall effect and particles have higher momentum concentration.

scholarly journals Computational fluid dynamics (CFD) simulation analysis on retinal gas cover rates using computational eye models

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Makoto Gozawa ◽  
Yoshihiro Takamura ◽  
Tomoe Aoki ◽  
Kentaro Iwasaki ◽  
Masaru Inatani
Keyword(s):  
Cfd Simulation ◽  
Simulation Analysis ◽  
Fluid Dynamic ◽  
Fluid Analysis ◽  
Intraocular Gas ◽  
Pars Plana ◽  
Computational Fluid Dynamics Cfd ◽  
Multiple Breaks ◽  
Gas Volume ◽  
Wall Wettability

AbstractWe investigated the change in the retinal gas cover rates due to intraocular gas volume and positions using computational eye models and demonstrated the appropriate position after pars plana vitrectomy (PPV) with gas tamponade for rhegmatogenous retinal detachments (RRDs). Computational fluid dynamic (CFD) software was used to calculate the retinal wall wettability of a computational pseudophakic eye models using fluid analysis. The model utilized different gas volumes from 10 to 90%, in increments of 10% to the vitreous cavity in the supine, sitting, lateral, prone with closed eyes, and prone positions. Then, the gas cover rates of the retina were measured in each quadrant. When breaks are limited to the inferior retina anterior to the equator or multiple breaks are observed in two or more quadrants anterior to the equator, supine position maintained 100% gas cover rates in all breaks for the longest duration compared with other positions. When breaks are limited to either superior, nasal, or temporal retina, sitting, lower temporal, and lower nasal position were maintained at 100% gas cover rates for the longest duration, respectively. Our results may contribute to better surgical outcomes of RRDs and a reduction in the duration of the postoperative prone position.

scholarly journals Effect of the Gas Volume Fraction on the Pressure Load of the Multiphase Pump Blade

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 650
Author(s):  
Guangtai Shi ◽  
Dandan Yan ◽  
Xiaobing Liu ◽  
Yexiang Xiao ◽  
Zekui Shu
Keyword(s):  
Flow Rate ◽  
Static Pressure ◽  
Volume Fraction ◽  
Pump Impeller ◽  
Impeller Blade ◽  
Multiphase Pump ◽  
Pressure Load ◽  
Gas Volume Fraction ◽  
Power Capability ◽  
Gas Volume

The gas volume fraction (GVF) often changes from time to time in a multiphase pump, causing the power capability of the pump to be increasingly affected. In the purpose of revealing the pressure load characteristics of the multiphase pump impeller blade with the gas-liquid two-phase case, firstly, a numerical simulation which uses the SST k-ω turbulence model is verified with an experiment. Then, the computational fluid dynamics (CFD) software is employed to investigate the variation characteristics of static pressure and pressure load of the multiphase pump impeller blade under the diverse inlet gas volume fractions (IGVFs) and flow rates. The results show that the effect of IGVF on the head and hydraulic efficiency at a small flow rate is obviously less than that at design and large flow rates. The static pressure on the blade pressure side (PS) is scarcely affected by the IGVF. However, the IGVF has an evident effect on the static pressure on the impeller blade suction side (SS). Moreover, the pump power capability is descended by degrees as the IGVF increases, and it is also descended with the increase of the flow rate at the impeller inlet. Simultaneously, under the same IGVF, with the increase of the flow rate, the peak value of the pressure load begins to gradually move toward the outlet and its value from hub to shroud is increased. The research results have important theoretical significance for improving the power capability of the multiphase pump impeller.

Sign in / Sign up

Export Citation Format

Share Document