Multiple Capillary Pressure Drop Standards

1975 ◽  
Vol 8 (2) ◽  
Author(s):  
C. H. Keith ◽  
J. A. Corbin
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Capillary Tube ◽  
Small Diameter ◽  
Flow Region ◽  
Glass Capillary ◽  
Pressure Drops ◽  
Laminar And Turbulent Flow ◽  
Glass Drawing

AbstractThis paper describes a simple device, consisting of a collection of glass capillary tubes, which can be used as a stable, pressure insensitive standard for calibrating pressure drop machines. For air flowing through a single capillary tube of the proper dimensions to give a pressure drop similar to that of a filter rod, the Reynolds number is about 2000, the boundary between laminar and turbulent flow. Since turbulent flow gives pressure drops which vary with atmospheric pressure, it is desirable to reduce this quantity to a level where laminar flow is always present. This can be accomplished by distributing the flow among 10 parallel capillaries of very small diameter. The capillaries were formed by drawing pyrex tubing on a Hupe glass drawing machine to a finished internaI diameter of .44 mm. Ten Iengths of this capillary were mounted in 8 mm tubing and were encased in a clear resin. After polymerization of the resin, the composite rod was sawed into appropriate lengths and cleaned in an ultrasonic bath. Microscopic examination of the finished tubes showed that each capillary was a clean, smooth-walled tube with a sharp entrance and exit. Calculation of the Reynolds number for the composite capillary gave a value of 314, which is well within the Iaminar flow region. The agreement between measured pressure drops of these standards and those calculated using Poiseuille's Iaw with an entry and exit correction is excellent. Daily measurements of the pressure drop of these standard tubes for a period of a month were conducted, and the random variability was found to be 1 % or Iess. Measurements of the pressure drop of these tubes at various pressures and temperatures covering the range of normaI laboratory conditions also demonstrated a lack of significant variability. Fouling of the tubes from atmospheric dust was not found to be a significant factor

SINGLE-PHASE HEAT TRANSFER AND PRESSURE DROP INSIDE INTERNALLY HELICAL-GROOVED HORIZONTAL SMALL-DIAMETER TUBES

2012 ◽  
Vol 20 (04) ◽  
pp. 1250022 ◽  
Author(s):  
NORIHIRO INOUE ◽  
JUNYA ICHINOSE
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Single Phase ◽  
Small Diameter ◽  
Flow Region ◽  
Helix Angle ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

An experimental study on pressure drop and heat transfer in single-phase was carried out using 10 types of internally helical-grooved and smooth small-diameter tubes with an outside diameter of 4 mm. The results are listed below: (1) In the turbulent flow region, fin height had the greatest effect, helix angle had only a minor effect, and the number of grooves had almost no effect upon the pressure drop versus the mass flow rate of the 4-mm grooved small-diameter tubes. In the laminar flow region, except for fin height, the shapes of the internal grooves had scarcely any effect upon pressure drop. (2) In the turbulent flow region, the heat transfer coefficients of the 4-mm grooved small-diameter tubes were greatly affected by fin height. The heat transfer coefficients became the maximum when a helix angle was near 15°, and there is a different tendency in the experiments of the pressure drop. On the other hand, there is almost no effect of the number of grooves. In the laminar flow region, there were no large differences in the heat transfer coefficients between the internally helical-grooved tubes and smooth small-diameter tube. (3) New empirical correlations for the friction factor and heat transfer coefficient in the laminar and turbulent flow regions were developed based on the experimental values. (4) The performance assessment in consideration of both heat transfer and pressure drop was indicated by using Colburn's analogy.

Numerical and Experimental Analysis of Turbulent Flow in Corrugated Pipes

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Henrique Stel ◽  
Rigoberto E. M. Morales ◽  
Admilson T. Franco ◽  
Silvio L. M. Junqueira ◽  
Raul H. Erthal ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Velocity Magnitude ◽  
Geometric Configurations ◽  
Corrugated Surfaces ◽  
Friction Factors

This article describes a numerical and experimental investigation of turbulent flow in pipes with periodic “d-type” corrugations. Four geometric configurations of d-type corrugated surfaces with different groove heights and lengths are evaluated, and calculations for Reynolds numbers ranging from 5000 to 100,000 are performed. The numerical analysis is carried out using computational fluid dynamics, and two turbulence models are considered: the two-equation, low-Reynolds-number Chen–Kim k-ε turbulence model, for which several flow properties such as friction factor, Reynolds stress, and turbulence kinetic energy are computed, and the algebraic LVEL model, used only to compute the friction factors and a velocity magnitude profile for comparison. An experimental loop is designed to perform pressure-drop measurements of turbulent water flow in corrugated pipes for the different geometric configurations. Pressure-drop values are correlated with the friction factor to validate the numerical results. These show that, in general, the magnitudes of all the flow quantities analyzed increase near the corrugated wall and that this increase tends to be more significant for higher Reynolds numbers as well as for larger grooves. According to previous studies, these results may be related to enhanced momentum transfer between the groove and core flow as the Reynolds number and groove length increase. Numerical friction factors for both the Chen–Kim k-ε and LVEL turbulence models show good agreement with the experimental measurements.

Experimental Investigation of Pressure Drop Characteristics of Viscous Fluid Flow Through Small Diameter Orifices

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Lalit Kumar Bohra ◽  
Leo M. Mincks ◽  
Srinivas Garimella
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Viscous Fluid ◽  
Euler Number ◽  
Small Diameter ◽  
Reynolds Numbers ◽  
Diameter Ratio ◽  
Operating Conditions ◽  
Turbulent Regime ◽  
Pressure Drops

Abstract An experimental study on the flow of a highly viscous fluid through small diameter orifices was conducted. Pressure drops were measured for each of nine orifices, including orifices of nominal diameter 0.5, 1, and 3 mm and three different orifice thicknesses, over wide ranges of flow rates and temperatures. The fluid under consideration exhibits steep dependence of the properties (changes of several orders of magnitude) as a function of temperature and pressure and is also non-Newtonian at the lower temperatures. At small values of Reynolds number, an increase in aspect ratio (length/diameter ratio of the orifice) causes an increase in Euler number. It was also found that at extremely low Reynolds numbers, the Euler number was very strongly influenced by the Reynolds number, while the dependence becomes weaker as the Reynolds number increases toward the turbulent regime, and the Euler number tends to assume a constant value determined by the aspect ratio and the diameter ratio. A two-region (based on Reynolds number) model was developed to predict Euler number as a function of diameter ratio, aspect ratio, viscosity ratio, and generalized Reynolds number. It is shown that for such a highly viscous fluid with some non-Newtonian behavior, accounting for the shear rate through the generalized Reynolds number results in a considerable improvement in the predictive capabilities of the model. Over the laminar, transition, and turbulent regions, the model predicts 86% of the data within ±25% for the geometry and operating conditions investigated in this study.

2E1 Active Control of Reattaching Flow Field at Low Reynolds Number Turbulent Flow Region

2013 ◽  
Vol 2013 (0) ◽  
pp. 143-144
Author(s):  
Naoto YAMAGUCHI ◽  
Isao TERUYA ◽  
Masaaki ISHIKAWA ◽  
Yuta MURO
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Turbulent Flow ◽  
Active Control ◽  
Low Reynolds Number ◽  
Flow Region ◽  
Low Reynolds

Further Investigation of Discharge Coefficient for PTC 6 Flow Nozzle in High Reynolds Number

2015 ◽  
Author(s):  
Noriyuki Furuichi ◽  
Yoshiya Terao ◽  
Shinichi Nakao ◽  
Keiji Fujita ◽  
Kazuo Shibuya
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
High Reynolds Number ◽  
Discharge Coefficient ◽  
Flow Region ◽  
Number Range ◽  
Discharge Coefficients ◽  
Reynolds Number Range ◽  
High Reynolds

The discharge coefficients of the throat tap flow nozzle based on ASME PTC 6 are measured in wide Reynolds number range from Red=5.8×104 to Red=1.4×107. The nominal discharge coefficient (the discharge coefficient without tap) is determined from the discharge coefficients measured for different tap diameters. The tap effects are correctly obtained by subtracting the nominal discharge coefficient from the discharge coefficient measured. Finally, by combing the nominal discharge coefficient and the tap effect determined in three flow regions, that is, laminar, transitional and turbulent flow region, the new equations of the discharge coefficient are proposed in three flow regions.

Frictional Pressure Drop in Micro-Channel

2004 ◽  
Author(s):  
Yasuo Koizumi ◽  
Hiroyasu Ohtake ◽  
Hiroki Takahashi ◽  
Yoshiaki Ohno
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Friction Factor ◽  
Frictional Pressure Drop ◽  
Turbulent Transition ◽  
Friction Factors ◽  
Turbulent Flow Regime ◽  
Form Pressure ◽  
Laminar And Turbulent Flow ◽  
Flow Through

The friction characteristics of water in a sub-millimeter scale channel were investigated experimentally. The friction factors and the critical Reynolds number were measured using water flow through circular tubes with diameters of 0.5, 0.25 and 0.17 mm. The experimental results show that the measured friction factor for water agreed well with the conventional Poiseuille (λ = 64/Re) and Blasius (λ = 0.316 Re−0.25) equations in laminar and turbulent flow regime; the laminar-turbulent transition Reynolds number was approximately 2300 for diameter 0.5 mm. For diameter 0.25 mm, the friction factor evaluated by the form pressure drop also agreed well with the Poiseuille equation. For diameter 0.17 mm, the measured total friction factor was close to the Poiseuille prediction.

Steady expiratory flow in dog lungs: an isovolume preparation

1981 ◽  
Vol 51 (5) ◽  
pp. 1331-1337 ◽  
Author(s):  
S. L. Sneddon ◽  
J. D. Brain
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Region ◽  
Flow Limitation ◽  
Opening Pressure ◽  
Pressure Flow ◽  
Pleural Surface ◽  
Airway Opening ◽  
Expiratory Flow

By supplying air and other gases through discs glued to the pleural surface, we studied steady expiratory flow at constant volume. Dog lungs were studied at constant PA - Ppl (alveolar minus pleural pressure) of 7 to 10 cmH2O, as increasing flow was achieved by increasing driving pressure [Ppl - Pao (airway opening pressure)]. Flow became limited (independent of further increases in Ppl - Pao) at between 3.5 and 5.5 l/s. Isovolume-pressure-flow (IVPF) curves constructed from forced expirations at graded efforts yielded similar maximal flows. When the airways were made rigid by drying, flow limitation was abolished. When various gases were passed through the dried lung Moody plots of normalized pressure drop (CD) vs. Reynolds number (Re) showed that all of the data could be plotted on a single curve. Although variable among animals, all Moody plots showed a laminar flow region at Re below 100 and an inertial region at Re above 10,000, with a distinct transition.

Partially filled pipes: experiments in laminar and turbulent flow

2018 ◽  
Vol 848 ◽  
pp. 467-507 ◽  
Author(s):  
Henry C.-H. Ng ◽  
Hope L. F. Cregan ◽  
Jonathan M. Dodds ◽  
Robert J. Poole ◽  
David J. C. Dennis
Keyword(s):  
Reynolds Number ◽  
Free Surface ◽  
Turbulent Flow ◽  
Pipe Flow ◽  
Large Scale ◽  
Open Channel ◽  
Streamwise Velocity ◽  
Flow Depth ◽  
Secondary Motion ◽  
Laminar And Turbulent Flow

Pressure-driven laminar and turbulent flow in a horizontal partially filled pipe was investigated using stereoscopic particle imaging velocimetry (S-PIV) in the cross-stream plane. Laminar flow velocity measurements are in excellent agreement with a recent theoretical solution in the literature. For turbulent flow, the flow depth was varied independently of a nominally constant Reynolds number (based on hydraulic diameter, $D_{H}$; bulk velocity, $U_{b}$ and kinematic viscosity $\unicode[STIX]{x1D708}$) of $Re_{H}=U_{b}D_{H}/\unicode[STIX]{x1D708}\approx 30\,000\pm 5\,\%$. When running partially full, the inferred friction factor is no longer a simple function of Reynolds number, but also depends on the Froude number $Fr=U_{b}/\sqrt{gD_{m}}$ where $g$ is gravitational acceleration and $D_{m}$ is hydraulic mean depth. S-PIV measurements in turbulent flow reveal the presence of secondary currents which causes the maximum streamwise velocity to occur below the free surface consistent with results reported in the literature for rectangular cross-section open channel flows. Unlike square duct and rectangular open channel flow the mean secondary motion observed here manifests only as a single pair of vortices mirrored about the vertical bisector and these rollers, which fill the half-width of the pipe, remain at a constant distance from the free surface even with decreasing flow depth for the range of depths tested. Spatial distributions of streamwise Reynolds normal stress and turbulent kinetic energy exhibit preferential arrangement rather than having the same profile around the azimuth of the pipe as in a full pipe flow. Instantaneous fields reveal the signatures of elements of canonical wall-bounded turbulent flows near the pipe wall such as large-scale and very-large-scale motions and associated hairpin packets whilst near the free surface, the signatures of free surface turbulence in the absence of imposed mean shear such as ‘upwellings’, ‘downdrafts’ and ‘whirlpools’ are present. Two-point spatio-temporal correlations of streamwise velocity fluctuation suggest that the large-scale coherent motions present in full pipe flow persist in partially filled pipes but are compressed and distorted by the presence of the free surface and mean secondary motion.

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