Experimental Characterization of Particle-Laden Air Flow Across Horizontal Pipe Junctions

2018 ◽  
Author(s):  
Tariq S. Khan ◽  
Mohamed Alshehhi ◽  
Xu Rumin ◽  
Saqib Salam
Keyword(s):  
Mass Fraction ◽  
Solid Phase ◽  
Flow Behavior ◽  
Air Flow ◽  
Industrial Applications ◽  
Solid Particles ◽  
Gas Flows ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Particle Sizer

There are several industrial applications in which two phase solid-gas flows are involved. At times, pipe junctions are involved where flow split takes place. Present study consists of experimental investigation of turbulent gas-solid two-phase flow through horizontal pipe junctions. The effects of air flow rate, branch diameter and pipe orientation at junctions are investigated on mass fraction, phase split and solid particles distribution across the junctions. Silica powder, in the monodispersed size of 15 μm was injected into the pipelines by a micro-feeder. The powder was entrained in an air flow which passed horizontally through a long straight channel of circular pipe with T and Y junctions. The main pipe was 51mm in diameter while the inlet superficial velocity of gas was varied from 5 m/s to 13.5m/s. The particles mass concentration was measured by the aerodynamic particle sizer (APS). Experimental results showed that solid phase split followed air flow split while decreasing the inlet air velocity caused major decrease in the mass fraction at junction pipe. The orientation of junction pipe has a significant effect on the flow behavior along the pipe. These results indicate that the behavior of solid particles is a complex phenomenon in pipe flows.

scholarly journals Effect of a Symmetric Contraction on the Concentration Profiles of a Particle-Laden Slurry

2011 ◽  
Author(s):  
A. Deshpande ◽  
K. Ramisetty ◽  
F. W. Chambers ◽  
M. E. McNally ◽  
R. M. Hoffman
Keyword(s):  
Single Phase ◽  
Solid Phase ◽  
Fluid Dynamic ◽  
Density Ratio ◽  
Primary Phase ◽  
Solid Particles ◽  
Concentration Profiles ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Slurry Concentration

In-line measurements and sample stream withdrawals for on-line and/or at-line measurements of slurries flowing in horizontal pipes can be complicated by nonuniform slurry profiles. More uniform profiles would improve measurements. Area contractions are a common means used to produce more uniform velocity fields for single phase flows. For example, contractions are used to condition the flow entering wind tunnel test sections and make velocity profiles more uniform at venturi throats. It was desired to determine whether area contractions could be used to make slurry concentration profiles more uniform in horizontal pipe flows. An ASME flow nozzle with a contraction diameter ratio of 0.5 was chosen as a well defined geometry to consider in a Computational Fluid Dynamic (CFD) study of the effects of a contraction on slurry concentration profiles. The pipe was 2.8 m long with a 50.8 mm diameter. The entrance of the contraction was placed at 35 pipe diameters from the inlet in fully developed flow. A length of 20 diameters followed the contraction. The slurry had a xylene liquid phase and an ADP solid phase with a density ratio of 1.7. The simulations were performed at primary phase velocities of 2 m/s and 4 m/s, corresponding to Reynolds numbers of 1.4E05 and 2.8E05. Spherical particle diameters of 38, 75, and 150 μm were used at concentrations of 0.05, 0.2, and 0.3. ANSYS FLUENT 12 software was used with the standard k-ε turbulence model and standard wall function. The mixture multi-phase model was used for the two-phase flow. An unstructured tetrahedral meshing scheme was used with 1.4 million elements. The grid was adjusted until the condition 30 < y+ <60 for the mesh point nearest the wall was satisfied. A grid refinement study was performed to insure grid independence. The computational scheme first was validated by comparing pipe flow velocity and concentration profiles to results in the literature. The computations performed with the contraction showed that in all cases the concentration profiles of the solid particles displayed greater uniformity than the profiles in the pipe upstream of the contraction. The effect of the contraction was more pronounced for the larger particles. As in the case of single phase flows, the contraction caused the axial turbulence intensity to decrease. The greater uniformity of the concentration profiles at the exit plane of the nozzle, suggest that the contraction can provide better conditions for performing measurements of a particle-laden slurry.

scholarly journals Prospects for the application of radiometric methods in the measurement of two-phase flows

2018 ◽  
Vol 180 ◽  
pp. 01001
Author(s):  
Marcin Zych
Keyword(s):  
Environmental Protection ◽  
Solid Phase ◽  
Life Sciences ◽  
Solid Particles ◽  
Gas Mixture ◽  
Gas Flows ◽  
Mathematical Methods ◽  
Two Phase Flows ◽  
Two Phase ◽  
Phase Mixture

The article constitutes an overview of the application of radiometric methods in the research of two-phase flows: liquid-solid particles and liquid-gas flows. The methods which were used were described on the basis of the experiments which were conducted in the Water Laboratory of the Wrocław University of Environmental and Life Sciences and in the Sedimentological Laboratory of the Faculty of Geology, Geophysics and Environmental Protection, AGH-UST in Kraków. The advanced mathematical methods for the analysis of signals from scintillation probes that were applied enable the acquisition of a number of parameters associated with the flowing two-phase mixture, such as: average velocities of the particular phases, concentration of the solid phase, and void fraction for a liquid-gas mixture. Despite the fact that the application of radioactive sources requires considerable carefulness and a number of state permits, in many cases these sources become useful in the experiments which are presented.

LDV measurements of an air–-solid two-phase flow in a horizontal pipe

1982 ◽  
Vol 120 ◽  
pp. 385-409 ◽  
Author(s):  
Yutaka Tsuji ◽  
Yoshinobu Morikawa
Keyword(s):  
Two Phase Flow ◽  
Air Flow ◽  
Solid Particles ◽  
Laser Doppler Velocimeter ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Frequency Spectra ◽  
Loading Ratio ◽  
Flow Turbulence

Measurements of air and solid velocities were made in an air-solid two-phase flow in a horizontal pipe by the use of a laser-Doppler velocimeter (LDV). The pipe was 30 mm inner diameter, and two kinds of plastic particles, 0.2 and 3.4 mm in diameter, were conveyed in addition to fine particles (ammonium chloride) for air-flow detection. The air velocities averaged over the pipe cross section ranged from 6 to 20m/s and the solid-to-air mass-flow ratio was up to 6. Simultaneous measurements of both air and 0.2 mm particle velocities were found possible by setting threshold values against the pedestal and Doppler components of the photomultiplier signal.As the loading ratio increased and the air velocity decreased, mean-velocity distributions of both phases increased asymmetrical tendency. I n the presence of 0.2mm particles, a flattening of the velocity profile was remarkable. The effects of the solid particles on air-flow turbulence varied greatly with particle size. That is, 3.4 mm particles increased the turbulence markedly, while 0-2 mm ones reduced it. The probability-density function of the air flow deviated from the normal distribution (Gaussian) in the presence of particles. Finally, the frequency spectra of air-flow turbulence were obtained in the presence of 0.2 mm particles by using a fast Fourier transform (FFT). As a result, it was found that t,he higher-frequency components increased with increasing loading ratio.

Mechanism Research on the Swirling Air Flow Compounded with Magnetic-Field Finishing

2008 ◽  
Vol 53-54 ◽  
pp. 51-55 ◽  
Author(s):  
Xiu Hong Li ◽  
Shi Chun Yang
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Air Flow ◽  
Abrasive Particle ◽  
Solid Particles ◽  
Two Phase ◽  
Machining Time ◽  
Machined Surface ◽  
Magnetic Field Coupling ◽  
Swirling Air Flow

A new finishing technology of the swirling air flow compounded with magnetic-field is advanced. Force acting on abrasive is analyzed by the action of airstream and magnetic-field coupling according to gas-solid particles two-phase flow. Finishing mechanism on the swirling air flow compounded with magnetic-field is illustrated, namely, burrs and microcosmic peak on the surface of workpiece are broken, grinded and cut via a great deal of abrasive particle impacting, microchipping and rolling machined surface. Unthreaded hole is experimented on the condition of changing magnetic induction intensity B and machining time t. Changing curve of surface roughness Ra along with time t is shown. Research indicates that machining time of the swirling air flow compounded with magnetic-field is short and machining efficiency is high. The longer machining time is, the smaller surface roughness Ra is and the better machining effect is.

Vortex Simulation for Behavior of Solid Particles Falling in Air

2011 ◽  
Author(s):  
Hisanori Yagami ◽  
Tomomi Uchiyama
Keyword(s):  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Air Flow ◽  
Three Dimensional ◽  
Particle Diameter ◽  
Vortex Method ◽  
Solid Particles ◽  
Particle Volume ◽  
Two Phase ◽  
Spherical Region

The behavior of small solid particles falling in an unbounded air is simulated. The particles, initially arranged within a spherical region in a quiescent air, are made to fall, and their fall induces the air flow around them, resulting in the gas-particle two-phase flow. The particle diameter and density are 1 mm and 7.7 kg/m3 respectively. A three-dimensional vortex method proposed by one of the authors is applied. The simulation demonstrates that the particles are accelerated by the induced downward air flow just after the commencement of their fall. It also highlights that the particles are whirled up by a vortex ring produced around the downward air flow after the acceleration. The effect of the particle volume fraction at the commencement of the fall is also explored.

scholarly journals Computational investigation of liquid-solid slurry flow through an expansion in a rectangular duct

2014 ◽  
Vol 62 (3) ◽  
pp. 234-240 ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Stefano Malavasi
Keyword(s):  
Volume Fraction ◽  
Particle Density ◽  
Fluid Model ◽  
Solid Volume Fraction ◽  
Solid Particles ◽  
Rectangular Duct ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Two Fluid Model ◽  
Two Fluid

Abstract The flow of a mixture of liquid and solid particles at medium and high volume fraction through an expansion in a rectangular duct is considered. In order to improve the modelling of the phenomenon with respect to a previous investigation (Messa and Malavasi, 2013), use is made of a two-fluid model specifically derived for dense flows that we developed and implemented in the PHOENICS code via user-defined subroutines. Due to the lack of experimental data, the two-fluid model was validated in the horizontal pipe case, reporting good agreement with measurements from different authors for fully-suspended flows. A 3D system is simulated in order to account for the effect of side walls. A wider range of the parameters characterizing the mixture (particle size, particle density, and delivered solid volume fraction) is considered. A parametric analysis is performed to investigate the role played by the key physical mechanisms on the development of the two-phase flow for different compositions of the mixture. The main focuses are the distribution of the particles in the system and the pressure recovery

Three-Dimensional Numerical Simulation of Convective Melting of Solid Particles in a Fluid

1999 ◽  
Author(s):  
Y. L. Hao ◽  
Y.-X. Tao
Keyword(s):  
Volume Fraction ◽  
Solid Phase ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Phase Changes ◽  
Solid Particles ◽  
Preliminary Calculation ◽  
Two Phase ◽  
Closed Set ◽  
Gravity Effects

Abstract A physical model of two-phase flow and heat-mass transfer with the phase changes based on the theory of interacting continua is proposed. All terms in the conservation equations are analyzed and the constitutive equations are presented. A closed set of governing equations describing the convective melting of solid particles in a fluid is obtained. The numerical method is developed for the solution of velocity, temperature, and volume fraction of solid phase for the three-dimensional melting in a rectangular cross-section channel. Preliminary calculation, including gravity effects, shows that the result is reasonable. This study provides a basis for the theoretical and experimental investigation of convective melting of solid particles in a fluid.

Pneumatic transport

1969 ◽  
Vol 39 (2) ◽  
pp. 407-432 ◽  
Author(s):  
P. R. Owen
Keyword(s):  
Fine Particles ◽  
Solid Wall ◽  
Electrostatic Charge ◽  
Difficult Problem ◽  
Solid Particles ◽  
Gas Velocity ◽  
Physical Explanation ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Different Types

Certain aspects of the transport of solid particles by a turbulent airstream are discussed, namely: the conveyance of particles in a horizontal pipe, including those carrying an appreciable electrostatic charge; the mechanism of deposition onto a solid wall; and the behaviour of fine particles in a shear flow, such as that in a round jet.Rough estimates of the effect of the particles on the gaseous turbulence are made, and a primitive physical explanation is offered of the observed velocitylag and pressure drop associated with the transport of particles in a horizontal pipe, under conditions where the influence of the particles’ weight is significant.Attention is drawn to the difficult problem of dynamically scaling a two-phase flow, and to the different types of interaction between the phases which can occur in a pipe according to its size, the gas velocity through it, and the physical characteristics of the particles.The paper is an annotated version of a survey presented to the I.U.T.A.M. Symposium on ‘Flow of fluid-solid mixtures’ held in Cambridge during March 1969.

Turbulent Solid-Liquid Two-Phase Flow Simulation With Turbulence Intensity and Time Scale Model

2009 ◽  
Author(s):  
Z. Mansoori ◽  
M. Saffar-Avval ◽  
B. Nojabaii ◽  
F. Behzad ◽  
G. Ahmadi
Keyword(s):  
Time Scale ◽  
Model Comparison ◽  
Two Phase Flow ◽  
Solid Phase ◽  
Solid Particles ◽  
Scale Model ◽  
Particle Collision ◽  
Phase Flow ◽  
Two Phase ◽  
Solid Liquid

Two-dimensional simulation of turbulent solid-liquid flow is carried out. The modeling is established for a two-phase flow of solid particles in a vertical pipe water flow. Governing equations of flow and turbulence field are solved in an Eulerian-Lagrangian approach by the use of k-τ (turbulence time scale) model and trajectories of the particles are obtained using the Lagrangian method with a deterministic inter-particle collision model. Comparison between the results of the model for mean and r.m.s velocities of the liquid and solid phase with the experimental results shows a good agreement. The effect of variation of particle density and concentration are studied.

Experimental Investigation of Horizontal Gas–Liquid Stratified and Annular Flow Using Wire-Mesh Sensor

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Ronald E. Vieira ◽  
Netaji R. Kesana ◽  
Carlos F. Torres ◽  
Brenton S. McLaury ◽  
Siamack A. Shirazi ◽  
...  
Keyword(s):  
Void Fraction ◽  
Test Section ◽  
Annular Flow ◽  
Parameter Extraction ◽  
Industrial Applications ◽  
Wire Mesh ◽  
Process Equipment ◽  
Two Phase ◽  
Cross Sectional ◽  
Horizontal Pipe

Stratified and annular gas–liquid flow patterns are commonly encountered in many industrial applications, such as oil and gas transportation pipelines, heat exchangers, and process equipment. The measurement and visualization of two-phase flow characteristics are of great importance as two-phase flows persist in many fluids engineering applications. A wire-mesh sensor (WMS) technique based on conductance measurements has been applied to investigate two-phase horizontal pipe flow. The horizontal flow test section consisting of a 76.2 mm ID pipe, 18 m long was employed to generate stratified and annular flow conditions. Two 16 × 16 wire configuration sensors, installed 17 m from the inlet of the test section, are used to determine the void fraction within the cross section of the pipe and determine interface velocities between the gas and liquid. These physical flow parameters were extracted using signal processing and cross-correlation techniques. In this work, the principle of WMS and the methodology of flow parameter extraction are described. From the obtained raw data time series of void fraction, cross-sectional mean void fraction, time averaged void fraction profiles, interfacial structures, and velocities of the periodic structures are determined for different liquid and gas superficial velocities that ranged from 0.03 m/s to 0.2 m/s and from 9 m/s to 34 m/s, respectively. The effects of liquid viscosity on the measured parameters have also been investigated using three different viscosities.

Sign in / Sign up

Export Citation Format

Share Document