An experimental study of pressure drop in helical pipes

1994 ◽  
Vol 444 (1921) ◽  
pp. 307-316 ◽  
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Cross Section ◽  
Circular Cross Section ◽  
Square Root ◽  
Dean Number ◽  
Curvature Ratio ◽  
Pressure Drops ◽  
Newtonian Flows ◽  
Fanning Friction Factor

Pressure drops of fully-developed incompressible laminar newtonian flows in helical pipes of constant circular cross-section having a finite pitch are experimentally investigated. For the case of loosely coiled pipes of 0 < η/λ < 41.22, f Re ( f is the Fanning friction factor and Re is the Reynolds number) is found to be proportional to the square root of the flow Dean number, Dn = Re λ ½ . Here λ and η are the normalized curvature ratio and torsion which incorporate both the coil radius and its pitch. In all cases studied, the experimental results for f Re are in excellent agreement with the theoretical prediction of Liu & Masliyah.

Experimental study of wall shear rates in the entry region of a curved tube

1979 ◽  
Vol 93 (3) ◽  
pp. 465-489 ◽  
Author(s):  
U. S. Choi ◽  
L. Talbot ◽  
I. Cornet
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Circular Cross Section ◽  
Current Method ◽  
Limiting Current ◽  
Dean Number ◽  
Shear Rates ◽  
Rigid Tube ◽  
Curved Tube ◽  
Wall Shear

Local wall shear rates in steady flow in the entry region of a curved tube have been measured by the electrochemical limiting current method. A semi-circular rigid tube of circular cross-section with radius ratio 1/7 has been employed for a range of Dean number between 139 and 2868. The circumferential and axial distributions of the wall shear rates have been measured at 20° circumferential increments at five different sections of the entry region.

Frictional Performance of U-Type Wavy Tubes

2003 ◽  
Vol 125 (5) ◽  
pp. 880-886 ◽  
Author(s):  
Ing Youn Chen ◽  
Yee Kang Lai ◽  
Chi-Chuan Wang
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Small Diameter ◽  
Straight Tube ◽  
Test Results ◽  
Dean Number ◽  
Spacer Length ◽  
Curvature Ratio ◽  
Pressure Drops ◽  
Test Range

Measurements of the pressure drops for water flowing in small diameter tubes having U-type wavy configuration are presented. The inner diameters of the test copper tubes D are 3.43, 5.07, and 8.29 mm, whereas the curvature ratios 2R/D and spacer length L/D span from 3.75 to 7.87 and 1.93 to 7.0, respectively. The test range of the Reynolds number for water is about 200<Re<18000. The measured pressure loss in U-type wavy tube includes the loss in U-bends and the loss caused by the distorted flow in the downstream straight tube. Thus, an equivalent friction factor, fB, is then defined. For both laminar and turbulent flow the bend friction factor increases with the decrease of dimensionless curvature ratio and spacer length. The test results indicate that the recent reported correlations by Popiel and Wojkowiak (2000) and Wojkowiak (2000) do not accurately predict the data. A simple friction factor equation is developed based on the experimental data with characterizing parameters like curvature ratio and spacer length, new Dean number, and the Reynolds number. A good agreement with a mean standard deviation of 5.6% is observed between the proposed correlation and the existing data, which includes the test results of this study and those from Popiel and Wojtkowiak (2000).

Extended Stokes series: laminar flow through a loosely coiled pipe

1978 ◽  
Vol 86 (1) ◽  
pp. 129-145 ◽  
Author(s):  
Milton Van Dyke
Keyword(s):  
Laminar Flow ◽  
Flow Speed ◽  
Square Root ◽  
Mean Flow ◽  
Dean Number ◽  
Curvature Ratio ◽  
Wide Range ◽  
Square Root Singularity ◽  
Flow Through ◽  
The One

Dean's series for steady fully developed laminar flow through a toroidal pipe of small curvature ratio has been extended by computer to 24 terms. Analysis suggests that convergence is limited by a square-root singularity on the negative axis of the square of the Dean number. An Euler transformation and extraction of the leading and secondary singularities at infinity render the series accurate for all Dean numbers. For curvature ratios no greater than$\frac{1}{250} $, experimental measurements of the laminar friction factor agree with the theory over a wide range of Dean numbers. In particular, they confirm our conclusion that the friction in a loosely coiled pipe grows asymptotically as the one-quarter power of the Dean number based on mean flow speed. This contradicts a number of incomplete boundary-layer analyses in the literature, which predict a square-root variation.

Equilibrium radial positions of neutrally buoyant spherical particles over the circular cross-section in Poiseuille flow

2017 ◽  
Vol 813 ◽  
pp. 750-767 ◽  
Author(s):  
Yusuke Morita ◽  
Tomoaki Itano ◽  
Masako Sugihara-Seki
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Poiseuille Flow ◽  
Equilibrium Position ◽  
Probability Function ◽  
Circular Cross Section ◽  
Spherical Particles ◽  
Inertial Migration ◽  
Entry Length ◽  
Neutrally Buoyant

An experimental study of the inertial migration of neutrally buoyant spherical particles suspended in the Poiseuille flow through circular tubes has been conducted at Reynolds numbers $(Re)$ from 100 to 1100 for particle-to-tube diameter ratios of ${\sim}$0.1. The distributions of particles in the tube cross-section were measured at various distances from the tube inlet and the radial probability function of particles was calculated. At relatively high $Re$, the radial probability function was found to have two peaks, corresponding to the so-called Segre–Silberberg annulus and the inner annulus, the latter of which was first reported experimentally by Matas et al. (J. Fluid Mech. vol. 515, 2004, pp. 171–195) to represent accumulation of particles at smaller radial positions than the Segre–Silberberg annulus. They assumed that the inner annulus would be an equilibrium position of particles, where the resultant lateral force on the particles disappears, similar to the Segre–Silberberg annulus. The present experimental study showed that the fraction of particles observed on the Segre–Silberberg annulus increased and the fraction on the inner annulus decreased further downstream, accompanying an outward shift of the inner annulus towards the Segre–Silberberg annulus and a decrease in its width. These results suggested that if the tubes were long enough, the inner annulus would disappear such that all particles would be focused on the Segre–Silberberg annulus for $Re<1000$. At the cross-section nearest to the tube inlet, particles were absent in the peripheral region close to the tube wall including the expected Segre–Silberberg annulus position for $Re>700$. In addition, the entry length after which radial migration has fully developed was found to increase with increasing $Re$, in contrast to the conventional estimate. These results may be related to the developing flow in the tube entrance region where the radial force profile would be different from that of the fully developed Poiseuille flow and there may not be an equilibrium position corresponding to the Segre–Silberberg annulus.

Analytical Solution for Newtonian Laminar Flow Through the Concave and Convex Ducts

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
M. Firouzi ◽  
S. H. Hashemabadi
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Friction Factor ◽  
Cross Section ◽  
Cross Sections ◽  
Fully Developed Flow ◽  
Pipe Flows ◽  
Dimensionless Velocity ◽  
Flow Through ◽  
Fanning Friction Factor

In this paper, the motion equation for steady state, laminar, fully developed flow of Newtonian fluid through the concave and convex ducts has been solved both numerically and analytically. These cross sections can be formed due to the sedimentation of heavy components such as sand, wax, debris, and corrosion products in pipe flows. The influence of duct cross section on dimensionless velocity profile, dimensionless pressure drop, and friction factor has been reported. Finally based on the analytical solutions three new correlations have been proposed for the product of Reynolds number and Fanning friction factor (Cf Re) for these geometries.

Numerical Investigation of Turbulent Magnetic Nanofluid Flow inside Straight Channels

2016 ◽  
Vol 819 ◽  
pp. 382-391 ◽  
Author(s):  
Nor Azwadi Che Sidik ◽  
Mohammed Raad Abdulwahab
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Cross Section ◽  
Volume Fraction ◽  
Numerical Study ◽  
Circular Cross Section ◽  
Average Diameter ◽  
Turbulent Regime ◽  
Reynolds Number Increase ◽  
Number Increase

A numerical study using computational fluid dynamics method with an approach of single phase has been presented in order to determine the effects of the concentration of the nanoparticles and flow rate on the convective heat transfer and friction factor in turbulent regime flowing through three different straight channels (straight, circular and triangular) with different Reynolds number (5000 ≤ Re ≤ 20000) using constant applied heat flux. The nanofluid was used consist of Fe3O4 magnetic nanoparticles with average diameter of (13nm) dispersed in water with four volume fraction (0, 0.2, 0.4, 0.6%). The results revealed that as volume fraction and Reynolds number increase Nusselt number increase and the heat transfer rate in circular cross section tube is better than that in square and triangular cross section channels.

Length Efficiency of the Etoile Flow Straightener: Numerical Experimentation

2011 ◽  
Author(s):  
Boualem Laribi ◽  
Abdelkader Youcefi ◽  
Elhacene Matene
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Velocity Profile ◽  
Cross Section ◽  
Circular Cross Section ◽  
The Other ◽  
Flow Parameters ◽  
Numerical Experimentation ◽  
Valve Position ◽  
Turbulence Intensity Profile

This article presents a numerical investigation of the development and the establishment of the flow in the presence of the Etoile flow straightener recommended in ISO 5167 (ISO 5167. Measurement of fluid flow by means of orifice plates, nozzles and venture plates inserted in circular cross-section conduits running full, 2003). The objective of this study is to examine the effectiveness length of the Etoile flow straightener, recommended by ISO 5167 with length of two pipe diameters, on the development and the establishment of the flow. The flow is produced by air in a 100mm pipe diameter and 40D of length with a Reynolds number of 2.5×105. The disturbance is a valve maintained at 100% and 50% open. The flow parameters examined are velocity profile, turbulence intensity profile, and the gyration of the fluid. Several measuring stations upstream and downstream of the unit are done. The code CFD Fluent is used for this simulation. The results obtained are compared according to directives of the standard ISO 5167. However, they show that for position valve 100% open the various lengths of the Etoile flow straightener do not present differences for the three flow parameters. On the other hand, for the valve position 50% open, the Etoile flow straightener with 2D length which presents the best performances according the standard.

Can the Dean number Alone Characterize Flow Similarity in Differently Bent Tubes?

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Krzysztof Cieślicki ◽  
Adam Piechna
Keyword(s):  
Flow Resistance ◽  
Classical Problem ◽  
Nonlinear Flow ◽  
Nonlinear Dependence ◽  
Dean Number ◽  
Curvature Ratio ◽  
Coiled Tube ◽  
Newtonian Flows ◽  
Curved Channels ◽  
Wide Range

Although flows of fluids in curved channels belong to a classical problem of fluid dynamics, most publications are restricted to investigations of flows in tube coils, or in single bends. This paper presents experimental and numerical (CFD) results concerning Newtonian flows in a set of multiple S-type bends of various orientations. Investigations were conducted for a wide range of Re values (0–3500) and for a significant curvature ratio lying between 0.05 and 0.29, which corresponds to De value falling within the range 0.02–1200. A coiled tube was also examined and treated as the reference geometry. It was shown, that despite a completely different velocity pattern, the nonlinear dependence of normalized flow resistance of wavy tubes and coiled tube of the same curvature ratio overlap within a significant range of De. A novel, close phenomenological formula to estimate the nonlinear flow resistance of tortuous tube in a wide range of De was proposed and compared with those in the literature. The conditions were also determined in which the De might be the only dimensionless group that characterizes such flows.

Pressure Drop of Liquid-Liquid Taylor Flow in Mini-Scale Coiled and Curved Tubing

2019 ◽  
Author(s):  
W. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Slug Flow ◽  
Silicone Oil ◽  
Radius Of Curvature ◽  
Asymptotic Model ◽  
Dean Number ◽  
Taylor Flow ◽  
Low Viscosity

Abstract This paper presents an experimental study on pressure drop using non-boiling liquid-liquid Taylor flow in mini scale coiled and curved tubing. Experiments were carried out to measure the pressure drop characteristics by varying the numbers of turns in coiled tubes and the lengths of curved tubes of less than one turn, such that Dean number, Reynolds number, radius of curvature, and coil pitch were considered. A set of narrow coiled tubes (ID = 1.59 mm, 1.27 mm, 1.016 mm) was used as test sections with different radii of curvature and overall lengths, and thus a different quantity of turns. Water and 1 cSt low viscosity silicone oil were used to create a segmented slug flow. An asymptotic model is developed based on the experimental results and previous models to predict the pressure drop, based on Dean number and dimensionless slug length. The effects of varying tube curvature and tube diameter are also studied. The results provide new insights into the effect of coiling and secondary flow on pressure drop for a liquid-liquid Taylor flow in mini scale systems.

Experimental Study of Nonlinear Effects under Torsion of the Uniform Cylinder with Initially Circular Cross Section

2015 ◽  
Vol 243 ◽  
pp. 29-34
Author(s):  
V.P. Bachurikhin ◽  
I.E. Keller ◽  
A.F. Merzlyakov ◽  
M.A. Yurlov
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Nonlinear Effect ◽  
Cylindrical Specimen ◽  
Axial Stress ◽  
Circular Cross Section ◽  
Nonlinear Effects ◽  
Fixed Length ◽  
Oscillatory Component

The results of experiments related to torsion of uniform cylindrical specimen at the fixed length between the specimens ends are presented in this paper. Axial stress has been found, initially stretching and then compressing the sample which has an oscillatory component with the period of one turn. Reasons of this nonlinear effect that are not described in the references are discussed here.

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