Effect of Tumbling and Burning on the Drag of Bluff Objects

1983 ◽  
Vol 105 (2) ◽  
pp. 174-178 ◽  
Author(s):  
K. W. Ragland ◽  
M. A. Mason ◽  
W. W. Simmons
Keyword(s):  
Drag Coefficient ◽  
Solid Fuel ◽  
Flat Surface ◽  
Free Fall ◽  
Wood Chips ◽  
Fall Velocity ◽  
Fuel Particles

The drag on various tumbling, nonburning wooden plates, cubes, rods, and wood chips was determined by measuring the free-fall velocity. The drag coefficient was reduced by a factor of 0.46 to 0.72 compared to the drag coefficient with the largest flat surface oriented perpendicular to the flow. The drag coefficient of burning wooden cubes and disks which are not tumbling was half that of identical nonburning, nontumbling cubes and disks. The drag coefficient of burning wooden cylinders with axes normal to the flow was slightly larger than nonburning cylinders with the same orientation. The information was obtained in order to better model the trajectory of solid fuel particles in furnaces.

Influence of Particle Shape on the Drag Coefficient for Isometric Particles

1994 ◽  
Vol 59 (12) ◽  
pp. 2583-2594 ◽  
Author(s):  
Miloslav Hartman ◽  
Otakar Trnka ◽  
Karel Svoboda ◽  
Václav Veselý
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Drag Coefficient ◽  
Fluidized Beds ◽  
Fluid Velocity ◽  
Particle Diameter ◽  
Free Fall ◽  
Fall Velocity ◽  
Gas Cleaning ◽  
Explicit Formulae

A comprehensive correlation has been developed of the drag coefficient for nonspherical isometric particles as a function the Reynolds number and the particle sphericity on the basis of data reported in the literature. The proposed formula covers the Stokes, the transitional and the Newton region. The predictions of the reported correlation have been compared to experimental data measured in this work with the dolomitic materials in respect to their use in calcination and gas cleaning processes with fluidized beds. Approximative explicit formulae have also been reported that make it possible to estimate the terminal free-fall velocity of a given particle or to predict the particle diameter corresponding to a fluid velocity of interest.

Free-Fall of Solid Particles through Fluids

1993 ◽  
Vol 58 (5) ◽  
pp. 961-982 ◽  
Author(s):  
Miroslav Hartman ◽  
John G. Yates
Keyword(s):  
Drag Coefficient ◽  
Newtonian Fluid ◽  
Free Fall ◽  
Terminal Velocity ◽  
Solid Particles ◽  
Fall Velocity ◽  
Predictive Relationships ◽  
Implicit And Explicit

A comprehensive, up-to-date review is presented of predictive relationships for the terminal, free-fall velocity of solid particles falling in an infinite Newtonian fluid. The study explores accuracy of the implicit and explicit equations in terms of the drag coefficient and the terminal velocity. Problems of predicting the terminal velocity of non-spherical, isometric as well as non-isometric, particles is discussed.

scholarly journals Homogeneous ignition and volatile combustion of single solid fuel particles in air and oxy-fuel conditions

Fuel ◽  
2021 ◽  
Vol 291 ◽  
pp. 120101
Author(s):  
Tao Li ◽  
Pooria Farmand ◽  
Christopher Geschwindner ◽  
Max Greifenstein ◽  
Jan Köser ◽  
...  
Keyword(s):  
Solid Fuel ◽  
Fuel Particles

scholarly journals SEDIGISM: the kinematics of ATLASGAL filaments

2018 ◽  
Vol 619 ◽  
pp. A166 ◽  
Author(s):  
M. Mattern ◽  
J. Kauffmann ◽  
T. Csengeri ◽  
J. S. Urquhart ◽  
S. Leurini ◽  
...  
Keyword(s):  
Unit Length ◽  
Dust Emission ◽  
Free Fall ◽  
Outer Radius ◽  
Line Of Sight ◽  
Fall Velocity ◽  
Automated Algorithm ◽  
Power Law Exponent ◽  
Continuum Data ◽  
Self Gravity

Analyzing the kinematics of filamentary molecular clouds is a crucial step toward understanding their role in the star formation process. Therefore, we study the kinematics of 283 filament candidates in the inner Galaxy, that were previously identified in the ATLASGAL dust continuum data. The 13CO(2 – 1) and C18O(2 – 1) data of the SEDIGISM survey (Structure, Excitation, and Dynamics of the Inner Galactic Inter Stellar Medium) allows us to analyze the kinematics of these targets and to determine their physical properties at a resolution of 30′′ and 0.25 km s−1. To do so, we developed an automated algorithm to identify all velocity components along the line-of-sight correlated with the ATLASGAL dust emission, and derive size, mass, and kinematic properties for all velocity components. We find two-third of the filament candidates are coherent structures in position-position-velocity space. The remaining candidates appear to be the result of a superposition of two or three filamentary structures along the line-of-sight. At the resolution of the data, on average the filaments are in agreement with Plummer-like radial density profiles with a power-law exponent of p ≈ 1.5 ± 0.5, indicating that they are typically embedded in a molecular cloud and do not have a well-defined outer radius. Also, we find a correlation between the observed mass per unit length and the velocity dispersion of the filament of m ∝ σv2. We show that this relation can be explained by a virial balance between self-gravity and pressure. Another possible explanation could be radial collapse of the filament, where we can exclude infall motions close to the free-fall velocity.

scholarly journals COMBUSTION SPEED PARAMETERS WHEN SIMULATING BY ANSYS FLUENT PROGRAM OF SOLID FUEL COMBUSTION

2020 ◽  
pp. 41-45
Author(s):  
M.M. Nekhamin ◽  
D.L. Bondzyk
Keyword(s):  
Burning Rate ◽  
Solid Fuel ◽  
Cfd Modeling ◽  
Solid Fuels ◽  
Ansys Fluent ◽  
Solid Fuel Combustion ◽  
The Difference ◽  
Fuel Particles ◽  
Combustion Of Solid Fuels ◽  
Combustion Speed

The existing difference in the models used to describe the burning rate of solid fuel particles, and, accordingly, the difference in the constants appearing in them, determines the relevance of the formulation of the relation between the constants known from the literature and the parameters that must be set in programs for CFD modeling of heat and power processes. This, in particular, relates to modeling the combustion of solid fuels in the well-known program ANSYS FLUENT. The paper outlines a possible approach to solving this problem. Bibl. 5, Fig. 3.

scholarly journals Applicability of Scaling Approach for Analysis of Pyrolysis and Gasification of Porous Structures Composed of Solid Fuel Particles

2012 ◽  
Vol 2012 ◽  
pp. 1-10
Author(s):  
Aliaksandr Alevanau ◽  
Pawel Donaj ◽  
Weihong Yang ◽  
Wlodzimierz Blasiak
Keyword(s):  
Experimental Research ◽  
Solid Fuel ◽  
The Self ◽  
Porous Structures ◽  
The Best Approximation ◽  
Self Organized ◽  
Volumetric Models ◽  
Fuel Particles ◽  
Kinetics Of ◽  
Reactive Properties

Experimental research on the pyrolysis and gasification of randomly packed straw pellets was conducted with an emphasis on the reactive properties of the shrinking porous structure of the pellets. The apparent kinetics of such pyrolysis was approximated by the random pore, grain, and volumetric models. The best approximation results were obtained with the grain and random pore models. The self-organized oscillations of the pellet conversion rate during pyrolysis were observed. Two complementary explanations of the phenomenon are proposed.

Numerical Simulation of Heavy Particle Dispersion Time Step and Nonlinear Drag Considerations

1992 ◽  
Vol 114 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Lian-Ping Wang ◽  
D. E. Stock
Keyword(s):  
Numerical Simulation ◽  
Numerical Experiments ◽  
Heavy Particle ◽  
Free Fall ◽  
Particle Dispersion ◽  
Integration Time ◽  
Fall Velocity ◽  
Time Step ◽  
Physical Experiments ◽  
Total Integration

Numerical experiments can be used to study heavy particle dispersion by tracking particles through a numerically generated instantaneous turbulent flow field. In this manner, data can be generated to supplement physical experiments. To perform the numerical experiments efficiently and accurately, the time step used when tracking the particles through the fluid must be chosen correctly. After finding a suitable time step for one particular simulation, the time step must be reduced as the total integration time increases and as the free-fall velocity of the particle increases. Based on the numerical calculations, we suggest that the nonlinear drag be included in a numerical simulation if the ratio of the particle’s Stokes free-fall velocity to the fluid rms velocity is greater than two.

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