Stirring of Fluid Particles through a Rotating Helical Pipe of Circular Cross-Section under Fully Developed Flow Condition

2011 ◽  
Vol 38 (2) ◽  
pp. 179-191
Author(s):  
M. A. Masud ◽  
Md. Mahmud Alam
Keyword(s):  
Cross Section ◽  
Flow Condition ◽  
Circular Cross Section ◽  
Fully Developed Flow ◽  
Helical Pipe ◽  
Fluid Particles

Unsteady Laminar Duct Flow With a Given Volume Flow Rate Variation

1999 ◽  
Vol 67 (2) ◽  
pp. 274-281 ◽  
Author(s):  
D. Das ◽  
J. H. Arakeri
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Circular Cross Section ◽  
Volume Flow ◽  
Rate Variation ◽  
Two Dimensional ◽  
Duct Flow ◽  
Fully Developed Flow ◽  
Gradient Variation

In this paper we give a procedure to obtain analytical solutions for unsteady laminar flow in an infinitely long pipe with circular cross section, and in an infinitely long two-dimensional channel, created by an arbitrary but given volume flow rate with time. In the literature, solutions have been reported when the pressure gradient variation with time is prescribed but not when the volume flow rate variation is. We present some examples: (a) the flow rate has a trapezoidal variation with time, (b) impulsively started flow, (c) fully developed flow in a pipe is impulsively blocked, and (d) starting from rest the volume flow rate oscillates sinusoidally. [S0021-8936(00)01702-5]

Friction Factor Determination for Flow Through Finite Wire-Mesh Woven-Screen Matrices

1997 ◽  
Vol 119 (4) ◽  
pp. 847-851 ◽  
Author(s):  
J. R. Sodre´ ◽  
J. A. R. Parise
Keyword(s):  
Cross Section ◽  
Circular Cross Section ◽  
Mesh Size ◽  
Packed Bed ◽  
Reynolds Numbers ◽  
Wire Mesh ◽  
Hydraulic Radius ◽  
Fully Developed Flow ◽  
Flow Through ◽  
Screen Mesh

Experiments were carried out to determine the pressure drop through an annular conduit filled with a plain square wire-mesh woven-screen matrix. The tests involved turbulent fully developed flow of air at steady-state conditions, with the modified Reynolds number (M(1−ε)/Re), based on the hydraulic radius of the packed bed, ranging from 5 × 10−4 to 5 × 10−3. The test section was built according to the geometry of a Stirling engine, simulating an annular regenerator with a radius ratio of 1.369 and a screen of mesh size 10. A corrected Ergun equation was used to correlate the experimental data, considering the wall effects. Comparisons with results obtained by other authors extended the validation of the correlation obtained to a wider range of modified Reynolds numbers (1 × 10−4 ≤ M(1 − ε)/Re ≤ 1) and to different screen mesh sizes. The correlation has been found to work for annular and circular cross-section beds.

Flow in Rotating Straight Pipes of Circular Cross Section

1971 ◽  
Vol 93 (3) ◽  
pp. 383-394 ◽  
Author(s):  
H. Ito¯ ◽  
K. Nanbu
Keyword(s):  
Friction Factor ◽  
Cross Section ◽  
Circular Cross Section ◽  
Constant Angular Velocity ◽  
Smooth Wall ◽  
Good Qualitative Agreement ◽  
Fully Developed Flow ◽  
Number Range ◽  
Friction Factors ◽  
Laminar And Turbulent Flow

The friction factor for fully developed flow in smooth wall straight pipes of circular cross section rotating at a constant angular velocity about an axis perpendicular to its own has been measured in the Reynolds number range from 20 to 60,000. Empirical equations for friction factors for small values of RΩ/R were presented for both laminar and turbulent flow. In the case of laminar flow, an approximate analysis based on the assumption that the flow consists of a frictionless central core surrounded by a boundary layer was presented. The results were in good qualitative agreement with experimental results in regard to the friction factor, velocity distribution in the plane of symmetry and pressure distribution along the circumferential wall of the pipe.

Flow through a rotating helical pipe with circular cross-section

2000 ◽  
Vol 21 (2) ◽  
pp. 213-220 ◽  
Author(s):  
Kyoji Yamamoto ◽  
Md.Mahmud Alam ◽  
Junich Yasuhara ◽  
Agus Aribowo
Keyword(s):  
Cross Section ◽  
Circular Cross Section ◽  
Helical Pipe ◽  
Flow Through

The Dean equations extended to a helical pipe flow

1989 ◽  
Vol 203 ◽  
pp. 289-305 ◽  
Author(s):  
M. Germano
Keyword(s):  
Secondary Flow ◽  
Cross Section ◽  
Pipe Flow ◽  
Circular Cross Section ◽  
Order Effect ◽  
Displacement Effect ◽  
Elliptical Cross ◽  
First Order ◽  
Helical Pipe ◽  
Axial Pressure Gradient

In this paper the Dean (1928) equations are extended to the case of a helical pipe flow, and it is shown that they depend not only on the Dean number K but also on a new parameter λ/[Rscr ] where λ is the ratio of the torsion τ to the curvature κ of the pipe axis and [Rscr ] the Reynolds number referred in the usual way to the pipe radius a and to the equivalent maximum speed in a straight pipe under the same axial pressure gradient. The fact that the torsion has no first-order effect on the flow is confirmed, but it is shown that this is peculiar to a circular cross-section. In the case of an elliptical cross-section there is a first-order effect of the torsion on the secondary flow, and in the limit λ/[Rscr ] → ∞ (twisted pipes, provided only with torsion), the first-order ‘displacement’ effect of the walls on the secondary flow, analysed in detail by Choi (1988), is recovered.Different systems of coordinates and different orders of approximations have recently been adopted in the study of the flow in a helical pipe. Thus comparisons between the equations and the results presented in different reports are in some cases difficult and uneasy. In this paper the extended Dean equations for a helical pipe flow recently derived by Kao (1987) are converted to a simpler form by introducing an appropriate modified stream function, and their equivalence with the present set of equations is recovered. Finally, the first-order equivalence of this set of equations with the equations obtained by Murata et al. (1981) is discussed.

On the fully developed flow in a curved pipe at large Dean number

1991 ◽  
Vol 434 (1891) ◽  
pp. 473-478 ◽  
Keyword(s):  
Cross Section ◽  
Asymptotic Form ◽  
Pipe Wall ◽  
Complete Solution ◽  
Circular Cross Section ◽  
Dean Number ◽  
Fully Developed Flow ◽  
Core Flow ◽  
Curved Pipe ◽  
Viscous Boundary

In this paper we consider the asymptotic form, for large Dean number, of the solution which describes the fully developed laminar flow in a curved pipe of circular cross section. Although we have not been able to provide a complete solution we present strong evidence in favour of an asymptotic structure which is based upon an in viscid core flow enclosed by viscous boundary layers at the pipe wall.

Steady flow in rapidly rotating circular expansions

1974 ◽  
Vol 66 (4) ◽  
pp. 657-671 ◽  
Author(s):  
J. S. Walker
Keyword(s):  
Steady Flow ◽  
Cross Section ◽  
Incompressible Flow ◽  
Reverse Flow ◽  
Circular Cross Section ◽  
Practical Case ◽  
Fully Developed Flow ◽  
Ekman Number ◽  
Pipe Flows ◽  
Flow Through

Inertialess incompressible flow through a rapidly rotating, variable-area conduit of circular cross-section is treated. For the practical case of an expansion (or contraction) placed between two pipes, the flow is strongly asymmetrical and involves regions of weak reverse flow in the expansion and downstream pipe, while the disturbance to the fully developed pipe flows persists for large, O(E−½) distances upstream and downstream, where E is the (small) Ekman number. The flow in the two pipes depends only on the ratio of their radii and is independent of the shape and length of the expansion. The startling implication of the disturbance's persistence is that, in practice, fully developed flow will almost never be realized in rapidly rotating pipes.

Research of Ultrasonic Flow Detection Method Based on Hydrodynamics Analysis

2012 ◽  
Vol 605-607 ◽  
pp. 923-928
Author(s):  
Lai Jun Sun ◽  
Ming Liang Liu ◽  
Ying Hou
Keyword(s):  
Laminar Flow ◽  
Flow Velocity ◽  
Cross Section ◽  
Flow Condition ◽  
Detection Method ◽  
Circular Cross Section ◽  
Correction Coefficient ◽  
Mean Velocity ◽  
Measurement Results ◽  
Flow Detection

Commonly referring to the flow velocity is surface mean velocity which evenly be distributed along the circular cross section of pipe. But the pipe velocity measured by ultrasonic flowmeter is linear mean velocity along ultrasonic transmission routes. They are different, so must be corrected. Using the hydrodynamics theory, this paper deduced the equation of flow correction coefficient in laminar flow condition and turbulent flow condition, and dynamically dealt with flow correction coefficient, finally analyzed and evaluated correction curves. The results indicate that this paper can accurately calibrate the ultrasonic flow and get the satisfactory measurement results.

Secondary flow in a rotating straight pipe

1954 ◽  
Vol 227 (1168) ◽  
pp. 133-139 ◽  
Keyword(s):  
Pressure Gradient ◽  
Secondary Flow ◽  
Cross Section ◽  
Circular Cross Section ◽  
Resistance Coefficient ◽  
Straight Pipe ◽  
Secondary Motion ◽  
Fluid Particles ◽  
Set Up

When a straight pipe of circular cross-section through which liquid is flowing under a pressure gradient is rotated about an axis perpendicular to it, secondary motion is set up and the fluid particles move in spirals relative to the pipe. This secondary motion has been studied in detail and an expression for the consequent rise in the resistance coefficient has been obtained.

Analytical Solutions for Laminar Fully-Developed Flow in Microchannels With Non-Circular Cross-Section

2009 ◽  
Author(s):  
A. Tamayol ◽  
M. Bahrami
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
General Solution ◽  
Cross Section ◽  
Cross Sections ◽  
Analytical Solutions ◽  
Circular Cross Section ◽  
Fully Developed Flow ◽  
Wide Range ◽  
Simply Connected

Analytical solutions are presented for laminar fully-developed flow in micro/minichannels of hyperelliptical and regular polygonal cross-sections. The considered geometries cover a wide range of common simply connected shapes including circle, ellipse, rectangle, rhomboid, star-shape, equilateral triangle, square, pentagon, and hexagon. Therefore, the present approach can be considered as a general solution. Predicted results for the velocity distribution and pressure drop are successfully compared with existing analytical solutions and experimental data collected from various sources for a variety of geometries, including: polygonal, rectangular, circular, elliptical, and rhombic cross-sections.

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