scholarly journals Effect of Friction Coupling on Discharge Velocity Profiles and Force Chain Distribution of Maize Particles in Silos

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Yong Feng ◽  
Caihua Yu ◽  
Fan Pan
Keyword(s):  
Mass Flow ◽  
Vertical Velocity ◽  
Rolling Friction ◽  
Velocity Profiles ◽  
Force Chain ◽  
Discharge Velocity ◽  
Maize Grain ◽  
Interparticle Friction ◽  
Funnel Flow ◽  
Total Discharge

The evolution mechanism of discharge velocity profiles and force chain distribution of maize particles in silos was studied based on the interaction between internal and external rolling friction of particles. Through EDEM, the silo and maize grain models were established for unloading simulation, whose flow pattern was compared with the silo unloading test to verify the rationality of the simulation. By slice observation, we compared and analyzed the time evolution rules of particle mesoscopic parameters under different friction conditions. The results show that the larger the interparticle friction coefficient is, the longer the total discharge time is and the smaller the coefficient of rolling friction between particles, the earlier the particle flow from mass flow to funnel flow. For silos with the funnel, the reduction of interparticle friction will change the limit between the mass flow and the funnel flow, thus increasing the area of the funnel flow. When the coefficient of rolling friction increases, the vertical velocity and angular velocity of the particle near the silo middle increase. However, the effects of internal and external friction coupling on the vertical velocity of the side particle, the horizontal velocity of the whole particle, and the spatial distribution and probability distribution of the force chain are more significant.

What You Need to Know to Reliably Handle Waste Coal

2003 ◽  
Author(s):  
Roderick J. Hossfeld ◽  
David A. Craig ◽  
Roger A. Barnum
Keyword(s):  
Mass Flow ◽  
Systematic Approach ◽  
Flow Patterns ◽  
Handling System ◽  
Flow Problems ◽  
Energy Facility ◽  
Anthracite Culm ◽  
Funnel Flow ◽  
Major Consideration ◽  
Waste Coal

Many power producers have been designing for, or switching to waste coal. A major consideration when dealing with waste coal is the design of the fuel handling system. Since waste coal is typically finer and more cohesive and therefore harder to handle in silos, bunkers, chutes and feeders, design of the handling system for reliable, non-stagnant flow is essential. This paper describes a systematic approach to designing and retrofitting handling systems to avoid bulk solids flow problems. Potential trouble areas such as coal hoppers, silos, bunkers, and transfer chutes are discussed. Mass flow and funnel flow patterns that develop in silos and bunkers are presented. Funnel flow results in large stagnant regions, which are a major problem for coals that combust easily and are prone to problems such as arching and ratholing. Mass flow patterns, which eliminate the stagnant coal regions, are also explained. Coal properties and bunker designs that result in mass flow and funnel flow are described. Transfer chute design techniques to avoid pluggages, reduce dusting, and minimize chute wear are discussed. The Panther Creek Energy facility in Nesquehoning, Pennsylvania is used as an example where solids flow handling methodologies were used to solve handling problems with anthracite culm. The modifications presented were required for reliable, stagnant-free coal flow, which prevented belt slippage and high belt loading on gravimetric feeders.

Solids flow velocity profiles in mass flow hoppers

1987 ◽  
Vol 42 (4) ◽  
pp. 737-744 ◽  
Author(s):  
H.G. Polderman ◽  
J. Boom ◽  
E. De Hilster ◽  
A.M. Scott
Keyword(s):  
Flow Velocity ◽  
Mass Flow ◽  
Velocity Profiles

scholarly journals DEVELOPMENT OF A MEASUREMENT SYSTEM FOR BED-FORMS AND VERTICAL VELOCITY PROFILES; OBSERVATION OF THE SAND-WAVES BEHAVIOR

2017 ◽  
Vol 73 (4) ◽  
pp. I_535-I_540
Author(s):  
Takashi KITSUDA ◽  
Atsuhiro YOROZUYA ◽  
Hiroshi KOSEKI ◽  
Yoriko YOSHIKAWA ◽  
Shoji OKADA ◽  
...  
Keyword(s):  
Vertical Velocity ◽  
Measurement System ◽  
Velocity Profiles ◽  
Sand Waves ◽  
Bed Forms

scholarly journals Dynamics of the Law Dome Ice Cap, Antarctica, as Found From Bore-Hole Measurements

1989 ◽  
Vol 12 ◽  
pp. 46-50 ◽  
Author(s):  
D.M. Etheridge
Keyword(s):  
Shear Strain ◽  
Vertical Velocity ◽  
Flow Line ◽  
Velocity Profiles ◽  
Surface Velocity ◽  
Ice Thickness ◽  
Shear Strain Rate ◽  
Orientation Data ◽  
Ice Cap ◽  
The Law

The internal dynamics of the Law Dome ice cap have been investigated by measuring the deformation of three bore holes located on an approximate flow line. Bore holes BHC1 (300 m deep) and BHC2 (344 m) were drilled in the coastal area to within several metres of bedrock and BHQ (418 m) was drilled about half-way towards the dome centre to about 50% of the ice thickness. Detailed measurements of orientation (inclination and azimuth), diameter, and temperature were taken through each bore hole over a 1 year span for BHC1 and BHC2 and a 10 year span for BHQ. The orientation data were reduced to obtain ∂u/∂z, a measure of the shear strain-rate. Changes in the depth of features located by bore-hole diameter measurements were used to obtain vertical velocity profiles. Other measurements discussed are temperatures, oxygen isotopes, crystal structure, surface velocities, and surface and bedrock topography.At the coastal sites, the ∂u/∂z profiles show two maxima in the lower third of the ice sheet. Flow due to the measured deformation accounts for about 55% of the surface velocity, the remainder being due to deformation and sliding in the basal zone. The vertical velocity profiles show mostly firn compression. The deeper ∂u/∂z maximum occurs in ice from the Wisconsin period which appears to deform more rapidly than the Holocene ice immediately above. The upper ∂u/∂z maximum may be related to the stress history of the ice, which can also explain the presence of significant shear strain and crystal-fabric development at only half the ice thickness at the BHQ site.

Discrete Element Modeling of Seed Metering as Affected by Roller Speed and Damping Coefficient

2020 ◽  
Vol 63 (1) ◽  
pp. 189-198
Author(s):  
Leno J. Guzman ◽  
Ying Chen ◽  
Hubert Landry
Keyword(s):  
Friction Coefficient ◽  
Mass Flow ◽  
Discrete Element ◽  
Rolling Friction ◽  
Angle Of Repose ◽  
Discrete Element Modeling ◽  
Flow Rates ◽  
Damping Coefficients ◽  
Mass Flow Rates ◽  
Rolling Friction Coefficient

Abstract. The development of highly efficient seed metering is required to meet the demands of modern seeding equipment. The discrete element method (DEM) was used to simulate metering of seeds with a fluted roller meter. This approach was chosen due to its capability to accurately represent granular material flow. The contact model selected for the DEM simulation was the linear rolling resistance model. Angle of repose experimental tests and simulations were performed to calibrate the rolling friction coefficient for peas. The calibrated value for the rolling friction coefficient was 0.016. A 192 mm cross-section of an air cart seed roller and housing was defined as the domain of the simulation. Sensitivity analysis showed that simulated mass flow rates were not sensitive to the selected damping coefficients (0.2, 0.5, and 0.8). Sensitivity indicator values varied between -0.049 and 0.088 for the range of damping coefficients and roller speeds studied. The simulated geometry of the seed meter and housing resulted in a steady flow of seeds, with discharged mass increasing linearly. The simulated mass flow rates were 34.0, 72.3, 110.4, 147.3, and 182.0 g s-1 for roller speeds of 10, 20, 30, 40, and 50 rpm, respectively. An experiment was performed to validate the simulation results. The predicted mass flow rate values of the simulation were within 10 g s-1 of the experimental results, with the largest relative error being 16.5%. Keywords: DEM, Damping, Metering, Peas, Rolling friction coefficient, Seed, Simulation.

Deep Learning Tomography by Mapping Full Seismic Waveforms to Vertical Velocity Profiles

2020 ◽  
Author(s):  
V. Kazei ◽  
O. Ovcharenko ◽  
P. Plotnitskii ◽  
D. Peter ◽  
X. Zhang ◽  
...  
Keyword(s):  
Deep Learning ◽  
Vertical Velocity ◽  
Velocity Profiles ◽  
Seismic Waveforms

Sensitivity of bed shear stress estimated from vertical velocity profiles: the problem of sampling resolution

1998 ◽  
Vol 23 (2) ◽  
pp. 133-139 ◽  
Author(s):  
Pascale M. Biron ◽  
Stuart N. Lane ◽  
André G. Roy ◽  
Kate F. Bradbrook ◽  
Keith S. Richards
Keyword(s):  
Shear Stress ◽  
Vertical Velocity ◽  
Velocity Profiles ◽  
Bed Shear Stress

Calculation of Unsteady Flows in Curved Pipes

2001 ◽  
Vol 123 (4) ◽  
pp. 869-877 ◽  
Author(s):  
H. A. Dwyer ◽  
A. Y. Cheer ◽  
T. Rutaganira ◽  
N. Shacheraghi
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Mass Flow ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Velocity Profiles ◽  
Frequency Parameter ◽  
Detailed Knowledge ◽  
Curved Pipes ◽  
Wall Shear

Highly unsteady three-dimensional flows in curved pipes with significant variation of flow geometry and flow parameters are studied. Using improvements in computational efficiency, detailed knowledge concerning flow structures is obtained. The numerical solutions of the Navier-Stokes equations have been obtained with a variation of the projection method, and the numerical method was enhanced by new algorithms derived from the physics of the flow. These enhancements include a prediction of the flow unsteady pressure gradient based on fluid acceleration and global pressure field corrections based on mass flow. This new method yields an order of magnitude improvement in the calculation’s efficiency, allowing the study of complex flow problems. Numerical flow simulations for oscillating flow cycles show that the curved pipe flows have a significant inviscid-like nature at high values of the frequency parameter. The shape of the velocity profiles is strongly influenced by the frequency parameter, whereas the influence of variations on the pipe cross-sectional area is shown to be rather weak. For large values of the frequency parameter the flow history strongly influences the low mass flow part of the cycle leading to highly unusual velocity profiles. The wall shear stress is studied for all the flows calculated. Our results show that wall shear stress is sensitive to area constrictions, the frequency parameter, as well as the shape of the entrance profile.

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