An Experimental Investigation of the Stability of Spiral Vortex Flow

1979 ◽  
Vol 21 (6) ◽  
pp. 397-402 ◽  
Author(s):  
M. M. Sorour ◽  
J. E. R. Coney
Keyword(s):  
Vortex Flow ◽  
Outer Cylinder ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Taylor Vortex ◽  
Vortex Cell ◽  
Annular Gap ◽  
Spiral Vortex ◽  
Axial Pressure Gradient ◽  
The Stability

The hydrodynamic stability of the flow in an annular gap, formed by a stationary outer cylinder and a rotatable inner cylinder, through which an axial flow of air can be imposed, is studied experimentally. Two annulus radius ratios of 0.8 and 0.955 are considered, representing wide- and narrow-gap conditions, respectively. It is shown that, when a large, axial pressure gradient is superimposed on the tangential flow induced by the rotation of the inner cylinder, the characteristics of the flow at criticality change significantly from those at zero and low axial flows, the axial length and width of the resultant spiral vortex departing greatly from the known dimensions of a Taylor vortex cell at zero axial flow. Also, the drift velocity of the spiral vortex is found to vary with the axial flow. Axial Reynolds numbers, Rea, of up to 700 are considered.

Flow Regimes in Two-Phase Hexane/Water Semibatch Vertical Taylor Vortex Flow

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Charlton Campbell ◽  
Michael G. Olsen ◽  
R. Dennis Vigil
Keyword(s):  
Vortex Flow ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Flow Patterns ◽  
Water Phase ◽  
Taylor Vortex ◽  
Two Phase ◽  
Annular Gap ◽  
Taylor Vortex Flow ◽  
Regime Map

Optical-based experiments were carried out using the immiscible pair of liquids hexane and water in a vertically oriented Taylor–Couette reactor operated in a semibatch mode. The dispersed droplet phase (hexane) was continually fed and removed from the reactor in a closed loop setup. The continuous water phase did not enter or exit the annular gap. Four distinct flow patterns were observed including (1) a pseudo-homogenous dispersion, (2) a weakly banded regime, (3) a horizontally banded dispersion, and (4) a helical flow regime. These flow patterns can be organized into a two-dimensional regime map using the azimuthal and axial Reynolds numbers as axes. In addition, the dispersed phase holdup was found to increase monotonically with both the azimuthal and axial Reynolds numbers. The experimental observations can be explained in the context of a competition between the buoyancy-driven axial flow of hexane droplets and the wall-driven vortex flow of the continuous water phase.

The Effect of Taylor Vortex Flow on the Radial Forces in an Annulus Having Variable Eccentricity and Axial Flow

1978 ◽  
Vol 100 (2) ◽  
pp. 210-214 ◽  
Author(s):  
J. E. R. Coney ◽  
J. Atkinson
Keyword(s):  
Vortex Flow ◽  
Outer Cylinder ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Radial Force ◽  
Taylor Vortex ◽  
Eccentric Annulus ◽  
Taylor Vortex Flow ◽  
Radial Forces ◽  
Force Variation

Results are presented in dimensionless form as obtained in an experimental study of the resultant radial force variation in an eccentric annulus formed by a stationary outer cylinder and a rotating inner cylinder, through which an axial flow of oil may be pumped. Two eccentricity ratios, 0.5 and 0.9, and three axial Reynolds numbers for the flow of the fluid in the annulus, 0, 25, and 50, are considered. It is shown that the onset of Taylor vortex flow has a marked effect on the magnitude and direction of the resultant radial force. The resultant forces and attitude angles are compared with those derived from Sommerfeld’s journal bearing theory. Comparisons are also made between critical Taylor numbers for the present investigation and those available in the literature.

The Effect of Taylor Vortex Flow on the Development Length in Concentric Annuli

1979 ◽  
Vol 21 (2) ◽  
pp. 59-64 ◽  
Author(s):  
D. A. Simmers ◽  
J. E. R. Coney
Keyword(s):  
Reynolds Number ◽  
Vortex Flow ◽  
Outer Cylinder ◽  
Outer Wall ◽  
Taylor Vortex ◽  
Rotational Flow ◽  
Development Length ◽  
Full Development ◽  
Annular Gap ◽  
Taylor Vortex Flow

Results are presented of an investigation into a developing, combined axial and rotational flow in an annular gap formed by a stationary outer cylinder and a rotatable inner cylinder for an annulus radius ratio of 0–8 and an axial Reynolds number of 1200. These results show that, in the Taylor vortex flow régime, the development length decreases with the parameter Re2a/Ta and that the greatest development length in an annular gap, for a given axial Reynolds number, occurs when the Taylor number is near to its critical value. Consideration of isothermal heat transfer through the outer wall of the annular gap suggests that, in the development of the flow, the Nusselt number rises to a high value before falling to a constant value, at full development.

The Effect of Temperature Gradient on the Stability of Flow between Vertical, Concentric, Rotating Cylinders

1979 ◽  
Vol 21 (6) ◽  
pp. 403-409 ◽  
Author(s):  
M. M. Sorour ◽  
J. E. R. Coney
Keyword(s):  
Temperature Gradient ◽  
Velocity Ratio ◽  
Axial Flow ◽  
Wave Number ◽  
Taylor Vortex ◽  
Effect Of Temperature ◽  
Neutral Stability ◽  
Radial Temperature ◽  
Annular Gap ◽  
The Stability

The effect of a radial temperature gradient on the hydrodynamic stability in the annular gap formed by two, vertical, concentric cylinders, the inner being rotatable and the outer both stationary and isothermally heated, was studied for the cases of zero and imposed axial fluid flow in the annular gap. For zero axial flow, it was found that the temperature gradient destabilizes the flow while not affecting the form of the secondary flow, viz. the classic Taylor vortex. For imposed axial flow, the point of neutral stability was modified only when natural convection was strong enough to affect the parabolic velocity profile associated with that flow; the extent of this modification was shown to depend on the direction of the axial flow. Also, the longitudinal temperature gradients within the gap were found to influence the axial wave number and the drift-velocity ratio.

Adiabatic and Diabatic Flow Studies by Shear Stress Measurements in Annuli With Inner Cylinder Rotation

1988 ◽  
Vol 110 (4) ◽  
pp. 399-405 ◽  
Author(s):  
Y. A. G. Abdallah ◽  
J. E. R. Coney
Keyword(s):  
Shear Stress ◽  
Outer Surface ◽  
Vortex Flow ◽  
Outer Cylinder ◽  
Reynolds Numbers ◽  
Isothermal Heating ◽  
Taylor Vortices ◽  
Annular Gap ◽  
Wide Range ◽  
Cylinder Rotation

The shear stress, occurring at the outer surface of a vertical annular gap formed by a stationary outer cylinder and a rotatable inner cylinder, was measured for a wide range of conditions, using a flush mounted probe. For annular gaps of radius ratio 0.8 and 0.9, axial flows of Reynolds numbers 100, 165, 200, and 300 were imposed under adiabatic and diabatic upflow and also diabatic downflow conditions. Under these conditions, the shear stress was determined over a range of Taylor numbers approaching 107, the flow being fully developed. Diabatic conditions were achieved by the isothermal heating of the outer surface of the gap. A primary regime, in which Taylor vortices are absent or exist away from the outer surface of the gap was identified. Secondary, tertiary and quaternary regimes, in which the vortex flow is in contact with that surface ensued. The contrast between the results for diabatic upflow and diabatic downflow gives an understanding of the effect of natural convection in these regimes.

Experiments on the stability of spiral flow at low axial Reynolds numbers

1962 ◽  
Vol 265 (1321) ◽  
pp. 198-214 ◽  
Keyword(s):  
Perturbation Theory ◽  
Viscous Flow ◽  
Hydrodynamic Stability ◽  
Outer Cylinder ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Rotating Cylinders ◽  
Spiral Flow ◽  
The Stability

The hydrodynamic stability of viscous flow between rotating cylinders with superposed axial flow has been studied experimentally. The experiments were confined to the case where the outer cylinder is at rest and the gap between cylinders is small. Particular attention has been given to small rates of axial flow. The results compare satisfactorily with Chandrasekhar’s perturbation theory valid under these conditions.

The stability of viscous flow between rotating concentric cylinders with an axial flow

1979 ◽  
Vol 366 (1727) ◽  
pp. 555-573 ◽  
Keyword(s):  
Reynolds Number ◽  
Viscous Flow ◽  
Axial Velocity ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Average Value ◽  
Concentric Cylinders ◽  
Axial Pressure Gradient ◽  
Second Mode ◽  
The Stability

The stability of viscous flow between concentric cylinders with the inner cylinder rotating and with an axial flow due to an axial pressure gradient is considered. The analysis is motivated, in part, by recent papers by Hasoon & Martin (1977) and Chung & Astill (1977). Results are given for radius ratios ɳ = R 1 / R 2 = 1 (the small-gap limit), 0.95, and 0.9, and for values of the axial Reynolds number R up to 100. Here R 1 and R 2 are the radii of the inner and outer cylinders, respectively. For the small-gap problem, the results are compared with those obtained by approximating the angular velocity and/or the axial velocity by average values. Two of the conclusions of the paper are that the small-gap problem is a valid approximation to the ɳ ≠ 1 problem for ɳ near 1, and that the approximation of the axial velocity by its average value leads to qualitatively and quantitatively incorrect results. In addition, we find that for axial Reynolds numbers of about ninety a second mode of instability arises and there is a discontinuity in the axial wavenumber of the critical disturbance as a function of the Reynolds number.

Development and Effects of Super-Critical Taylor-Vortex Flow in a Lightly Loaded Journal Bearing

1974 ◽  
Vol 96 (1) ◽  
pp. 28-35 ◽  
Author(s):  
R. C. DiPrima ◽  
J. T. Stuart
Keyword(s):  
Vortex Flow ◽  
Axial Direction ◽  
Basic Flow ◽  
Circular Cylinders ◽  
Taylor Vortex ◽  
Taylor Vortices ◽  
Taylor Vortex Flow ◽  
Secondary Motion ◽  
The Stability ◽  
Unified Description

At sufficiently high operating speeds in lightly loaded journal bearings the basic laminar flow will be unstable. The instability leads to a new steady secondary motion of ring vortices around the cylinders with a regular periodicity in the axial direction and a strength that depends on the azimuthial position (Taylor vortices). Very recently published work on the basic flow and the stability of the basic flow between eccentric circular cylinders with the inner cylinder rotating is summarized so as to provide a unified description. A procedure for calculating the Taylor-vortex flow is developed, a comparison with observed properties of the flow field is made, and formulas for the load and torque are given.

Turbulent flow between counter-rotating concentric cylinders: a direct numerical simulation study

2008 ◽  
Vol 615 ◽  
pp. 371-399 ◽  
Author(s):  
S. DONG
Keyword(s):  
Turbulent Flow ◽  
Large Scale ◽  
Outer Cylinder ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Taylor Vortex ◽  
Small Scale ◽  
Mean Flow ◽  
Concentric Cylinders ◽  
High Reynolds

We report three-dimensional direct numerical simulations of the turbulent flow between counter-rotating concentric cylinders with a radius ratio 0.5. The inner- and outer-cylinder Reynolds numbers have the same magnitude, which ranges from 500 to 4000 in the simulations. We show that with the increase of Reynolds number, the prevailing structures in the flow are azimuthal vortices with scales much smaller than the cylinder gap. At high Reynolds numbers, while the instantaneous small-scale vortices permeate the entire domain, the large-scale Taylor vortex motions manifested by the time-averaged field do not penetrate a layer of fluid near the outer cylinder. Comparisons between the standard Taylor–Couette system (rotating inner cylinder, fixed outer cylinder) and the counter-rotating system demonstrate the profound effects of the Coriolis force on the mean flow and other statistical quantities. The dynamical and statistical features of the flow have been investigated in detail.

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