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.

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.

scholarly journals The investigation of the height effect of a slit microchannel with a textured wall on its hydrodynamic drag

2021 ◽  
Vol 2119 (1) ◽  
pp. 012050
Author(s):  
A S Lobasov ◽  
A V Minakov
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Drag Coefficient ◽  
Slip Length ◽  
Reynolds Numbers ◽  
Hydrodynamic Drag ◽  
Channel Height ◽  
Relative Pressure ◽  
Effective Slip Length ◽  
Effective Slip

Abstract The numerical investigation of the fluid flow in a slit microchannel with a textured wall was carried out. The effect of the channel height on the hydrodynamic drag coefficient, as well as on the pressure drop in such channel and the effective slip length on the wall for various Reynolds numbers, are presented in the paper. The channel length was 100 µm, and its height was varied from 25 µm to 500 µm. The Reynolds number was varied from 0.1 to 100. The main studied characteristics were compared to the similar ones obtained for a channel with normal walls (no-slip conditions). It was found that the pressure drop in such textured microchannel was lower as compared to a conventional channel for any of its heights and for any Reynolds numbers. The dependences of the relative pressure drop, effective slip length, and drag coefficient on the Reynolds number were obtained for different channel heights. The drag coefficient was described as 20/Re for the average values of the channel height. A correlation that describes the dependence of the friction factor on the Reynolds number for small and large heights of the channel was proposed. The accuracy of the proposed correlation was about 90%.

Note on the numerical solution for unsteady viscous flow past a circular cylinder

1968 ◽  
Vol 31 (4) ◽  
pp. 815-818 ◽  
Author(s):  
D. B. Ingham
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Viscous Fluid ◽  
Drag Coefficient ◽  
Reasonable Agreement ◽  
Mesh Size ◽  
Reynolds Numbers ◽  
Time Interval ◽  
Unsteady Viscous Flow ◽  
Starting Flow

The starting flow of a viscous fluid past a circular cylinder at Reynolds numbers 40 and 100 has been obtained by a numerical method. The method used is that developed by Payne (1957) but it has been extended here to cover a larger time interval.At Reynolds number 40 Payne's result for the drag coefficient at time t = 6 is in reasonable agreement with Kawaguti's (1953) result for the steady case but if Payne's computation, is extended to time t ≈ 24, the result is in better agreement with Apelt's (1961) result for the steady case. Also, a further investigation into the case R = 100 shows that Payne's mesh size is too crude. Similar observations can be made concerning the size of the standing vortices downstream of the circular cylinder and how they grow in time.

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.

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.

A new model for predicting drag coefficient and settling velocity of spherical and non-spherical particle in Newtonian fluid

2017 ◽  
Vol 321 ◽  
pp. 242-250 ◽  
Author(s):  
Xianzhi Song ◽  
Zhengming Xu ◽  
Gensheng Li ◽  
Zhaoyu Pang ◽  
Zhaopeng Zhu
Keyword(s):  
Drag Coefficient ◽  
Spherical Particle ◽  
Newtonian Fluid ◽  
Settling Velocity ◽  
New Model

scholarly journals The Profile Drag of Yawed Wings of Infinite Span

1951 ◽  
Vol 3 (3) ◽  
pp. 211-229 ◽  
Author(s):  
A.D. Young ◽  
T.B. Booth
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Drag Coefficient ◽  
Experimental Evidence ◽  
Flat Plate ◽  
Transition Point ◽  
Reynolds Numbers ◽  
External Pressure ◽  
Basic Assumptions ◽  
Angle Of Yaw

SummaryA method is developed for calculating the profile drag of a yawed wing of infinite span, based on the assumption that the form of the spanwise distribution of velocity in the boundary layer, whether laminar or turbulent, is insensitive to the chordwise pressure distribution. The form is assumed to be the same as that accepted for the boundary layer on an unyawed plate with zero external pressure gradient. Experimental evidence indicates that these assumptions are reasonable in this context. The method is applied to a flat plate and the N.A.C.A. 64-012 section at zero incidence for a range of Reynolds numbers between 106 and 108, angles of yaw up to 45°, and a range of transition point positions. It is shown that the drag coefficients of a flat plate varies with yaw as cos½ Λ (where Λ is the angle of yaw) if the boundary layer is completely laminar, and it varies as if the boundary layer is completely turbulent. The drag coefficient of the N.A.C.A. 64-012 section, however, varies closely as cos½ Λ for transition point positions between 0 and 0.5 c. Further calculations on wing sections of other shapes and thicknesses and more detailed experimental checks of the basic assumptions at higher Reynolds numbers are desirable.

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