scholarly journals Influence of particle density distributions of their settling velocity for narrow size fractions

2014 ◽  
Vol 30 (1) ◽  
pp. 105-122 ◽  
Author(s):  
Agnieszka Surowiak
Keyword(s):  
Settling Velocity ◽  
Particle Density ◽  
Size Fractions ◽  
Density Distributions

Streszczenie Prędkość opadania ziaren jest cechą rozdziału, według której dokonuje się idealny rozdział ziaren w procesie wzbogacania wosadzarŚ. Uwzględnienie kompleksowych właściwości geometrycznych ziaren (wielkość i kształt ziaren) oraz fizycznych (gęstość ziaren) prowadzi do wyliczenia rozkładu granicznej prędkości opadania ziaren. Zatem graniczna prędkość opadania ziaren jest to złożona cecha rozdziału, zawierająca w sobie trzy podstawowe cechy proste ziarna (gęstość, wielkość i kształt ziania). W artykule podano metodykę wyznaczania rozkładu prędkości opadania w próbce ziaren sferycz- nych dla turbulentnego charakteru ruchu ziaren, w którym prędkość opadania wyraża się wzorem Newiona-Rittingera. Ze względu na to, że zarówno gęstość jak i wielkość ziama są zmiennymi losowymi o pewnych rozkładach, również prędkość opadania jako funkcja tych zmiennych jest zmienną loscwą. Korzystając z twierdzeń rachunku prawdopodobieństw* odnoszących się do funkcji zmiennych losowych podano w zór na funkcję gęstości rozkładu prędkości opadania oraz wyliczono rozkłady prędkości dla kOku kombinacji rozkładów wielkości i gęstości ziama na podstawie ekspe- rymentu przemysłowego. Artykuł przedstawia symulacyjne określanie rozkładów prędkości opadania ziaren sferycznych przy założeniu, że ziama mają kształt kulisty o średnicy równej średnicy projekcyjnej ziaren niere- gularnych. W takim przypadku, na graniczną prędkość opadania ziaren będzie miał wpływ rozkład właściwości densymetrycznych.

Settling Behavior of Particles in Bubble Containing Newtonian Fluids: Experimental Study and Model Development

2021 ◽  
Author(s):  
Silin Jing ◽  
Xianzhi Song ◽  
Zhaopeng Zhu ◽  
Buwen Yu ◽  
Shiming Duan
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Volume Concentration ◽  
Settling Velocity ◽  
Particle Density ◽  
Particle Diameter ◽  
Newtonian Fluids ◽  
Spherical Particles ◽  
Bubble Volume ◽  
Particle Reynolds Number

Abstract Accurate description of cuttings slippage in the gas-liquid phase is of great significance for wellbore cleaning and the control accuracy of bottom hole pressure during MPD. In this study, the wellbore bubble flow environment was simulated by a constant pressure air pump and the transparent wellbore, and the settling characteristics of spherical particles under different gas volume concentrations were recorded and analyzed by highspeed photography. A total of 225 tests were conducted to analyze the influence of particle diameter (1–12mm), particle density (2700–7860kg/m^3), liquid viscosity and bubble volume concentration on particle settling velocity. Gas drag force is defined to quantitatively evaluate the bubble’s resistance to particle slippage. The relationship between bubble drag coefficient and particle Reynolds number is obtained by fitting the experimental results. An explicit settling velocity equation is established by introducing Archimedes number. This explicit equation with an average relative error of only 8.09% can directly predict the terminal settling velocity of the sphere in bubble containing Newtonian fluids. The models for predicting bubble drag coefficient and the terminal settling velocity are valid with particle Reynolds number ranging from 0.05 to 167 and bubble volume concentration ranging from 3.0% to 20.0%. Besides, a trial-and-error procedure and an illustrative example are presented to show how to calculate bubble drag coefficient and settling velocity in bubble containing fluids. The results of this study will provide the theoretical basis for wellbore cleaning and accurate downhole pressure to further improve the performance of MPD in treating gas influx.

scholarly journals Can terminal settling velocity and drag of natural particles in water ever be predicted accurately?

2020 ◽  
Author(s):  
Onno J. I. Kramer ◽  
Peter J. de Moel ◽  
Shravan K. R. Raaghav ◽  
Eric T. Baars ◽  
Wim H. van Vugt ◽  
...  
Keyword(s):  
Drinking Water ◽  
Measurement Errors ◽  
Settling Velocity ◽  
Particle Density ◽  
Fixed Bed ◽  
Drinking Water Treatment ◽  
Liquid System ◽  
Solid Particles ◽  
Spherical Particles ◽  
Fluidised Bed

Abstract. Natural particles are frequently applied in drinking water treatment processes in fixed bed reactors, in fluidised bed reactors, and in sedimentation processes to clarify water and to concentrate solids. When particles settle, it has been found that in terms of hydraulics, natural particles behave differently when compared to perfectly round spheres. To estimate the terminal settling velocity of single solid particles in a liquid system, a comprehensive collection of equations is available. For perfectly round spheres, the settling velocity can be calculated quite accurately. However, for naturally polydisperse non-spherical particles, experimentally measured settling velocities of individual particles show considerable spread from the calculated average values. This work aimed to analyse and explain the different causes of this spread. To this end, terminal settling experiments were conducted in a quiescent fluid with particles varying in density, size and shape. For the settling experiments, opaque and transparent spherical polydisperse and monodisperse glass beads were selected. In this study, we also examined drinking water related particles, like calcite pellets and crushed calcite seeding material grains, both applied in drinking water softening. Polydisperse calcite pellets were sieved and separated to acquire more uniformly dispersed samples. In addition, a wide variety of grains with different densities, sizes and shapes were investigated for their terminal settling velocity and behaviour. The derived drag coefficient was compared with well-known models such as Brown–Lawler. A sensitivity analysis showed that the spread is caused to a lesser extent by variations in fluid properties, measurement errors and wall effects. Natural variations in specific particle density, path trajectory instabilities and distinctive multi-particle settling behaviour caused a slightly larger degree of spread. In contrast, greater spread is caused by variations in particle size, shape and orientation.

scholarly journals Study of impact of sonic energy waves on the rate of precipitation of particles in liquid

2021 ◽  
Author(s):  
Abdisamed Sheik-Qasim
Keyword(s):  
Settling Velocity ◽  
Particle Density ◽  
Particle Diameter ◽  
Hydroxypropyl Cellulose ◽  
Fluid Viscosity ◽  
Small Particles ◽  
Particle Settling ◽  
Sonic Energy ◽  
Different Diameters ◽  
Good Agreement

The effects of sonic energy waves on the settling velocity of small particles in water were studied. A design of experiment (DOE) with five variables (frequency, amplitude, particle diameter, particle density and fluid viscosity) at two or three levels was conducted to obtain the particle settling velocity as the response. The DOE data were analyzed both experimentally and by a statistical multiple regression software. It was concluded that when sound frequency and amplitude in the range of 0 to 500 Hz and 2 to 3 Vrms (root mean square) respectively were applied to plastic particles of three different diameters (2,381 μm, 3,175 μm, and 4,763 μm) and two different densities ... their effects on the particle settling velocity in hydroxypropyl cellulose (HPC) solutions of three different viscosities ... were insignificant. The regression analysis gave an equation that is in good agreement with the experimental data.

Comparison of theoretical and experimental particle density distributions of traces in a d.c. arc

1982 ◽  
Vol 37 (10) ◽  
pp. 895-901 ◽  
Author(s):  
I. Holclajtner-Antunović ◽  
V. Vukanović ◽  
V. Georgijević ◽  
V. Čadež
Keyword(s):  
Particle Density ◽  
Density Distributions ◽  
Experimental Particle

Charged particle density distributions in Au induced interactions with emulsion nuclei at 10.7 A GeV

1995 ◽  
Vol 352 (3-4) ◽  
pp. 472-478 ◽  
Author(s):  
M.I. Adamovich ◽  
M.M. Aggarwal ◽  
Y.A. Alexandrov ◽  
R. Amirikas ◽  
N.P. Andreeva ◽  
...  
Keyword(s):  
Charged Particle ◽  
Particle Density ◽  
Density Distributions ◽  
Charged Particle Density
Sign in / Sign up

Export Citation Format

Share Document