scholarly journals SEDIMENTATION OF A BIDISPERSE CLUSTER OF SOLID SPHERICAL PARTICLES

2020 ◽  
pp. 77-85
Author(s):  
V.A. Arkhipov ◽  
◽  
S.A. Basalaev ◽  
N.N. Zolotorev ◽  
K.G. Perfil’eva ◽  
...  
Keyword(s):  
Experimental Study ◽  
Drag Coefficient ◽  
Initial Velocity ◽  
Silicone Oil ◽  
Reynolds Numbers ◽  
Spherical Particles ◽  
Cluster Evolution ◽  
Qualitative Pattern ◽  
Steel Balls ◽  
Spherical Container

A new method for the experimental study of gravitational sedimentation of a polydisperse cluster of solid spherical particles in a viscous fluid is presented. The method is based on the preliminary ultrasonic mixing of the particles in a spherical container and assumes the introduction of a spherical cluster of particles at a given concentration and zero initial velocity into a fluid. This method is used to determine sedimentation characteristics of a bidisperse cluster of particles (steel balls, 2 and 3 mm in diameter) in silicone oil. A qualitative pattern of the cluster evolution, a sedimentation rate, and a drag coefficient are obtained. A comparative analysis of sedimentation characteristics of monodisperse and bidisperse particle clusters is carried out in the range of Reynolds numbers Re = (0.30÷0.66)·10−3. It is shown that, in contrast to a monodisperse cluster of particles, the drag coefficient of the bidisperse cluster of particles does not correspond to a correlation CD = 24/Rec for the Stokes sedimentation.

Drag coefficient of a sphere in a non-stationary flow: new results

2007 ◽  
Vol 463 (2088) ◽  
pp. 3323-3345 ◽  
Author(s):  
G Jourdan ◽  
L Houas ◽  
O Igra ◽  
J.-L Estivalezes ◽  
C Devals ◽  
...  
Keyword(s):  
Drag Coefficient ◽  
Stationary Flow ◽  
Reynolds Numbers ◽  
Spherical Particles ◽  
Steady Flows ◽  
Two Phase ◽  
Spider Web ◽  
Wide Range ◽  
The Difference ◽  
Sphere Drag

The drag coefficient of a sphere placed in a non-stationary flow is studied experimentally over a wide range of Reynolds numbers in subsonic and supersonic flows. Experiments were conducted in a shock tube where the investigated balls were suspended, far from all the tube walls, on a very thin wire taken from a spider web. During each experiment, many shadowgraph photos were taken to enable an accurate construction of the sphere's trajectory. Based on the sphere's trajectory, its drag coefficient was evaluated. It was shown that a large difference exists between the sphere drag coefficient in steady and non-steady flows. In the investigated range of Reynolds numbers, the difference exceeds 50%. Based on the obtained results, a correlation for the non-stationary drag coefficient of a sphere is given. This correlation can be used safely in simulating two-phase flows composed of small spherical particles immersed in a gaseous medium.

scholarly journals A Numerical and Experimental Study of the Aerodynamics and Stability of a Horizontal Parachute

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Mazyar Dawoodian ◽  
Abdolrahman Dadvand ◽  
Amir Hassanzadeh
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Numerical Simulations ◽  
Drag Coefficient ◽  
Reynolds Numbers ◽  
Flow Conditions ◽  
High Reynolds Numbers ◽  
High Reynolds ◽  
The Stability ◽  
Good Agreement

The flow past a parachute with and without a vent hole at the top is studied both experimentally and numerically. The effects of Reynolds number and vent ratio on the flow behaviour as well as on the drag coefficient are examined. The experiments were carried out under free-flow conditions. In the numerical simulations, the flow was considered as unsteady and turbulent and was modelled using the standard - turbulence model. The experimental results reveal good agreement with the numerical ones. In both the experiments and numerical simulations, the Reynolds number was varied from 85539 to 357250 and the vent ratio was increased from zero to 20%. The results show that the drag coefficient decreases by increasing the Reynolds number for all the cases tested. In addition, it was found that at low and high Reynolds numbers, the parachutes, respectively, with 4% vent ratio and without vent are deemed more efficient. One important result of the present work is related to the effect of vent ratio on the stability of the parachute.

scholarly journals Initial Velocity Effect on Acceleration Fall of a Spherical Particle through Still Fluid

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Zegao Yin ◽  
Zhenlu Wang ◽  
Bingchen Liang ◽  
Li Zhang
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Spherical Particle ◽  
Initial Velocity ◽  
Reynolds Numbers ◽  
Large Reynolds Number ◽  
Fall Velocity ◽  
Fall Time ◽  
Velocity Effect ◽  
The Relationship

A spherical particle’s acceleration fall through still fluid was investigated analytically and experimentally using the Basset-Boussinesq-Oseen equation. The relationship between drag coefficient and Reynolds number was studied, and various parameters in the drag coefficient equation were obtained with respect to the small, medium, and large Reynolds number zones. Next, some equations were used to derive the finite fall time and distance equations in terms of certain assumptions. A simple experiment was conducted to measure the fall time and distance for a spherical particle falling through still water. Sets of experimental data were used to validate the relationship between fall velocity, time, and distance. Finally, the initial velocity effect on the total fall time and distance was discussed with different terminal Reynolds numbers, and it was determined that the initial velocity plays a more important role in the falling motion for small terminal Reynolds numbers than for large terminal Reynolds number scenarios.

scholarly journals Экспериментальное исследование коэффициента гидродинамического сопротивления охлажденной твердой сферы при малых числах Рейнольдса

2021 ◽  
Vol 47 (7) ◽  
pp. 46
Author(s):  
В.А. Архипов ◽  
С.А. Басалаев ◽  
К.Г. Перфильева ◽  
С.Н. Поленчук ◽  
А.С. Усанина
Keyword(s):  
Viscous Fluid ◽  
Drag Coefficient ◽  
Spherical Particle ◽  
Temperature Difference ◽  
Sedimentation Rate ◽  
Silicone Oil ◽  
Reynolds Numbers ◽  
Hydrodynamic Drag ◽  
Gravitational Sedimentation

The results of experimental studying the gravitational sedimentation of a cooled solid spherical particle in a viscous fluid in the range of Reynolds numbers Re = 0.01÷1.32 are presented. A significant decrease of stationary sedimentation rate (up to 30%) of a cooled particle is shown. Empirical dependencies for the sedimentation rate and hydrodynamic drag coefficient of the particle in the range of temperature difference between liquid (glycerol, silicone oil) and particle ∆T = (0÷210) K are obtained.

Experimental investigations of flow over NACA airfoils 0021 and 4412 of wind turbine blades with and without Tubercles

2021 ◽  
pp. 0309524X2110071
Author(s):  
Usman Butt ◽  
Shafqat Hussain ◽  
Stephan Schacht ◽  
Uwe Ritschel
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Wind Turbine ◽  
Critical Region ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Experimental Investigations ◽  
Wind Turbine Blades

Experimental investigations of wind turbine blades having NACA airfoils 0021 and 4412 with and without tubercles on the leading edge have been performed in a wind tunnel. It was found that the lift coefficient of the airfoil 0021 with tubercles was higher at Re = 1.2×105 and 1.69×105 in post critical region (at higher angle of attach) than airfoils without tubercles but this difference relatively diminished at higher Reynolds numbers and beyond indicating that there is no effect on the lift coefficients of airfoils with tubercles at higher Reynolds numbers whereas drag coefficient remains unchanged. It is noted that at Re = 1.69×105, the lift coefficient of airfoil without tubercles drops from 0.96 to 0.42 as the angle of attack increases from 15° to 20° which is about 56% and the corresponding values of lift coefficient for airfoil with tubercles are 0.86 and 0.7 at respective angles with18% drop.

Experimental Study on Racetrack-Shaped Holes Impingement Cooling With Bump Type Roughening Element

2012 ◽  
Author(s):  
Chiyuki Nakamata ◽  
Yoji Okita ◽  
Takashi Yamane ◽  
Yoshitaka Fukuyama ◽  
Toyoaki Yoshida
Keyword(s):  
Experimental Study ◽  
Flow Condition ◽  
Reynolds Numbers ◽  
Main Flow ◽  
The Other ◽  
Relative Location ◽  
Target Plate ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Cooling Air

Cooling effectiveness of an impingement cooling with array of racetrack-shaped impingement holes is investigated. Two types of specimens are investigated. One is a plain target plate and the other is a plate roughened with bump type elements. Sensitivity of relative location of bump to impingement hole on the cooling effectiveness is also investigated. Experiments are conducted under three different mainflow Reynolds numbers ranging from 2.6×105 to 4.7×105, with four different cooling air Reynolds numbers for each main flow condition. The cooling air Reynolds numbers are in the range from 1.2×103 to 1.3×104.

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