Flow in a rotating non-aligned straight pipe

1984 ◽  
Vol 144 ◽  
pp. 297-310 ◽  
Author(s):  
J. Berman ◽  
L. F. Mockros
Keyword(s):  
Velocity Profile ◽  
Axial Velocity ◽  
Reynolds Numbers ◽  
Straight Pipe ◽  
Regular Perturbation ◽  
Axial Velocity Profile ◽  
Axial Profile ◽  
Flow Through ◽  
Effects Of Rotation ◽  
Two Parameters

A third-order regular perturbation solution is developed for laminar flow through a straight pipe that is rotating about an axis not aligned with the pipe axis. Coriolis accelerations produce transverse secondary velocities (similar to those in flow through coiled tubes) and modify the axial-velocity profile. The effects of rotation on the velocity fields are shown to depend on two parameters: (i) the product of axial and rotational Reynolds numbers, and (ii) the square of the rotational Reynolds number itself. Even though their strength increases with increases in parameter magnitudes, transverse circulations are qualitatively insensitive to parametric values. The axial profile, on the other hand, can be significantly modified by the rotation; the zeroth-order parabolic axial profile can be skewed toward the outside, dimpled in the centre with maximums on either side of the centreline, or both, depending on the values of the two parameters. The modification of the axial-velocity profile has important ramifications in the design of heat/mass-transfer devices.

Steady Laminar Flow through Twisted Pipes: Fluid Flow in Square Tubes

1981 ◽  
Vol 103 (4) ◽  
pp. 785-790 ◽  
Author(s):  
J. H. Masliyah ◽  
K. Nandakumar
Keyword(s):  
Laminar Flow ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Dissipation Term ◽  
Axial Velocity Profile ◽  
Secondary Motion ◽  
Qualitative Nature ◽  
Flow Through ◽  
Steady Laminar

The Navier-Stokes equation in a rotating frame of reference is solved numerically to obtain the flow field for a steady, fully developed laminar flow of a Newtonian fluid in a twisted tube having a square cross-section. The macroscopic force and energy balance equations and the viscous dissipation term are presented in terms of variables in a rotating reference frame. The computed values of friction factor are presented for dimensionless twist ratios, (i.e., length of tube over a rotation of π radians normalized with respect to half the width of tube) of 20, 10, 5 and 2.5 and for Reynolds numbers up to 2000. The qualitative nature of the axial velocity profile was observed to be unaffected by the swirling motion. The secondary motion was found to be most important near the wall.

Turbulent Flow in Axially Rotating Pipes

1980 ◽  
Vol 102 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Mitsukiyo Murakami ◽  
Kouji Kikuyama
Keyword(s):  
Velocity Profile ◽  
Turbulent Flow ◽  
Flow Pattern ◽  
Axial Velocity ◽  
Hydraulic Loss ◽  
Pressure Distributions ◽  
Axial Velocity Profile ◽  
Fully Developed Turbulent Flow ◽  
Smooth Pipe ◽  
Pipe Rotation

Experimental results concerning the flow pattern and hydraulic resistance in a rotating pipe are described. A fully developed turbulent flow was introduced into a long smooth pipe rotating about its axis, and changes of the flow pattern, together with hydraulic loss within the pipe, were examined by measuring the velocity and pressure distributions across sections at various distance from the pipe entrance. Increase of pipe rotation continuously reduces the hydraulic loss and gradually changes the axial velocity profile from a turbulent type to a laminar one. Governing factors for these changes are discussed.

The Elimination of Wall Effects in Axial-Flow Compressor Stages

1953 ◽  
Vol 57 (508) ◽  
pp. 241-243
Author(s):  
J. M. Stephenson
Keyword(s):  
Velocity Profile ◽  
Axial Velocity ◽  
Radial Profile ◽  
Axial Flow ◽  
Gas Velocity ◽  
Wall Effects ◽  
Axial Velocity Component ◽  
Axial Velocity Profile ◽  
Flow Compressor ◽  
Work Done

Compressor stages are usually designed on the assumption that the gas velocity is nowhere affected by the friction at the walls. The only way in which viscosity is taken into account is in the assumed efficiency, and in a guessed “work-done factor,” which ensures that by aiming high the required work is actually attained.It is known that the radial profile of the axial velocity component becomes more and more peaked through successive stages of a compressor, so that the assumptions just quoted become very inaccurate. It is possible that the efficiency of a stage could be raised considerably if the axial velocity profile were controlled; moreover up to 20 per cent. more work could be done if a “ work-done factor ” did not have to be applied.

A Theoretical Analysis of the Influence of Rotation on Flow in a Tube Rotating about a Parallel Axis with Uniform Angular Velocity

1965 ◽  
Vol 69 (651) ◽  
pp. 201-202 ◽  
Author(s):  
W. D. Morris
Keyword(s):  
Angular Velocity ◽  
Velocity Profile ◽  
Axial Velocity ◽  
Cylindrical Tube ◽  
Fluid Flows ◽  
Leading Edge ◽  
Pressure Fields ◽  
Axial Velocity Profile ◽  
Parallel Axis ◽  
Arbitrary Axis

When fluid flows in a tube which rotates about an arbitrary axis, the presence of centripetal and Coriolis acceleration components modify the velocity and pressure fields which exist in the absence of rotation. Barua considered the case of an incompressible fluid flowing in laminar motion through a cylindrical tube which was rotating about an axis perpendicular to itself with uniform angular velocity. For distances well away from the tube entrance Barua illustrated that secondary flow in the r-θ plane occurred and that the axial velocity profile was distorted towards the leading edge of the tube. Since the pressure gradient along the tube is proportional to the gradient of the axial velocity profile at the tube wall the rotation thus has a consequential influence on the resistance to flow offered by the tube.

Convective Heat Transfer of the Flow through a Rotating Circular Straight Pipe

2001 ◽  
Vol 17 (2) ◽  
pp. 79-91
Author(s):  
U. Lei ◽  
Arthur C. Y. Yang
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Reynolds Numbers ◽  
Straight Pipe ◽  
Constant Wall Temperature ◽  
Fully Developed Flow ◽  
Flow Through ◽  
Prandtl Numbers ◽  
Scaling Analyses ◽  
Gradient Condition

ABSTRACTLaminar heat transfer for large ranges of Reynolds numbers, rotational Reynolds numbers, and Prandtl numbers are studied numerically for incompressible fully developed flow in a circular straight pipe, which is rotating constantly about an axis perpendicular to its own axis under the constant wall temperature gradient condition. There exist four types of local Nusselt number distributions associated with the four different flow regimes for different parameters depending on the relative importance of different forces. Correlations of the averaged Nusselt number are also provided. When the Prandtl number is sufficiently large, the temperature distribution in the core is determined essentially by the secondary flow. Scaling analyses are provided for understanding the essential physics of the problem.

Gas Dispersion in a Model Pulmonary Bifurcation During Oscillatory Flow

1997 ◽  
Vol 119 (3) ◽  
pp. 309-316 ◽  
Author(s):  
M. Nishida ◽  
Y. Inaba ◽  
K. Tanishita
Keyword(s):  
Velocity Profile ◽  
Axial Velocity ◽  
Oscillatory Flow ◽  
Gas Transport ◽  
Main Bronchus ◽  
High Frequency Oscillation ◽  
Laser Doppler Velocimeter ◽  
Straight Tube ◽  
Gas Dispersion ◽  
Axial Velocity Profile

In order to clarify the gas transport process in high-frequency oscillation, we measured the axial velocity profile and the axial effective diffusivity in a single asymmetric bifurcating tube, based on the Horsfield airway model, with sinusoidally oscillatory flow. The axial velocity profiles were measured using a laser-Doppler velocimeter, and the effective diffusivities were evaluated using a simple bolus injection method. The axial velocity profile was found to be nonuniform, promoting axial gas dispersion by the spread of the concentration profile and lateral mixing. The geometric asymmetry of the bifurcation was responsible for the difference in gas transport between the main bronchi. The axial gas transport in the left main bronchus was 2.3 times as large as that of the straight tube, whereas the gas transport in the right main bronchus was slightly larger than that of the straight tube. Thus localized variation in gas transport characterized the heterogeneous respiratory function of the lung.

Compressor Design

1953 ◽  
Vol 57 (511) ◽  
pp. 463-463
Author(s):  
R. G. Taylor
Keyword(s):  
Velocity Profile ◽  
Axial Velocity ◽  
Axial Flow ◽  
Technical Note ◽  
Basic Design ◽  
Wall Effects ◽  
Axial Flow Compressor ◽  
Axial Velocity Profile ◽  
Compressor Design ◽  
Flow Compressor

In Mr. J. M. Stephenson's Technical Note, “ The Elimination of Wall Effects in Axial-Flow Compressor Stages,” in the April 1953 issue of the Journal, the author suggests that the blade rows of an axial flow compressor are so closely spaced as to ensure that the axial velocity profile is unchanged across the rows. Whether this statement is correct or not such an assumption regarding the axial velocity profile is a basic design condition and when made it will not leave any flexibility in the choice of the function f(r).

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