An Experimental Procedure for Determining Both the Density and Flow Rate From Pressure Drop Measurements in a Cylindrical Pipe

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
Ghislain Michaux ◽  
Olivier Vauquelin ◽  
Elsa Gauger
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
Pressure Change ◽  
Gas Mixture ◽  
Gas Extraction ◽  
Cylindrical Pipe ◽  
Flow Area ◽  
Number Range ◽  
Experimental Procedure ◽  
Pressure Drops

An experimental procedure was developed for determining both the density and flow rate of a gas from measurements of pressure drops caused by an abrupt flow area contraction in a cylindrical pipe. Experiments were carried out by varying the density and flow rate of a light gas mixture of air and helium, spanning a Reynolds number range from 0.2×104 to 3.4×104. From experimental results, a procedure was then proposed for evaluating the density from pressure change measurements in the scope of light gas extraction experiments.

scholarly journals A Review of Passive Micromixers with a Comparative Analysis

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 455 ◽  
Author(s):  
Wasim Raza ◽  
Shakhawat Hossain ◽  
Kwang-Yong Kim
Keyword(s):  
Reynolds Number ◽  
Comparative Analysis ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Number Range ◽  
Pressure Drops ◽  
Convection Diffusion ◽  
Wide Range ◽  
Quantitative Analyses ◽  
Mixing Costs

A wide range of existing passive micromixers are reviewed, and quantitative analyses of ten typical passive micromixers were performed to compare their mixing indices, pressure drops, and mixing costs under the same axial length and flow conditions across a wide Reynolds number range of 0.01–120. The tested micromixers were selected from five types of micromixer designs. The analyses of flow and mixing were performed using continuity, Navier-Stokes and convection-diffusion equations. The results of the comparative analysis were presented for three different Reynolds number ranges: low-Re (Re ≤ 1), intermediate-Re (1 < Re ≤ 40), and high-Re (Re > 40) ranges, where the mixing mechanisms are different. The results show a two-dimensional micromixer of Tesla structure is recommended in the intermediate- and high-Re ranges, while two three-dimensional micromixers with two layers are recommended in the low-Re range due to their excellent mixing performance.

Effect of Low Reynolds Number Mixed Convection on Channel Flows Structure

2012 ◽  
Author(s):  
Ahmed Elatar ◽  
Kamran Siddiqui
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
Wall Temperature ◽  
Heated Wall ◽  
Mean Velocity ◽  
Number Range ◽  
Flow Rates ◽  
Wall Heating ◽  
The Mean ◽  
Low Reynolds

The effect of wall heating on low Reynolds numbers channel flow has been investigated experimentally. The experiments were conducted at heated bottom wall temperatures from 30 °C to 50 °C for two flow rates 0.0210 and 0.0525 kg/s, corresponding to the Reynolds number range of 150 and 750 (in the absence of heating). The results showed that the initially laminar flow became turbulent due to wall heating, and that wall heating has a significant influence on both the mean and turbulent velocity fields. The mean velocity profiles were altered by the convective currents. The magnitude of mean streamwise velocity near the heated wall increased with an increase in the wall temperature. A back flow near the upper channel wall was also observed primarily at the lower flow rate which diminished for the high flow rate. The magnitude of backflow increased with an increase in the wall temperature. The turbulent intensities were found to increase with an increase in the wall temperature for both flow rates. The result also showed the presence of strong vortices originating from the heated wall and advecting towards the central core of the channel.

scholarly journals Parametric Experiments on Coaxial Airblast Jet Atomization

1990 ◽  
Author(s):  
Zoltan Farago ◽  
Norman Chigier
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
High Speed ◽  
Liquid Sheet ◽  
Velocity Range ◽  
Air Flow Rate ◽  
Flow Conditions ◽  
Number Range ◽  
Reynolds Number Range ◽  
Air Stream

Experiments using high speed, high magnification, and high contrast photography on airblast coaxial atomizers were carried out to study the wave characteristics of liquid surfaces, ligament breakup, and droplet formation. Liquid flow rate was changed from 4 to 50 kg/h, corresponding to a velocity range of 1.5 to 18 m/s, and a Reynolds number range of 1400 to 18000. Air flow rate was varied from 8 to 70 kg/h, corresponding to a velocity range of 22 to 180 m/s, and a Reynolds number range of 13000 to 105000. Tube wall thicknesses of 145 and 320 microns were used. Under different flow conditions, different jet instabilities (capillary, helical and Kelvin-Helmholtz) and different dominant mechanisms of ligament formation were observed. One of the most surprising experimental results is that, under certain flow conditions, the coaxial round liquid jet, surrounded by an axisymmetric annular air stream, forms a flat curling liquid sheet. This liquid sheet breaks into droplet clouds with a frequency of a few thousand Hertz and emits strong oscillations and fluctuating, highly non-axisymmetric vibrations.

scholarly journals Experimental Investigation of Heat Transfer of Nanofluid in Elliptical and Circular Tubes

2021 ◽  
Vol 8 (4) ◽  
pp. 665-671
Author(s):  
Ammar M. Al-Tajer ◽  
Abdulhassan A. Kramallah ◽  
Ali M. Mohsen ◽  
Nabeel Sameer Mahmoud
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Friction Factor ◽  
Volume Concentration ◽  
Pressure Change ◽  
Experimental Comparison ◽  
Distilled Water ◽  
Cross Sectional ◽  
Pressure Drops ◽  
Circular Tubes

The paper presents experimental comparison of forced convection for steady state turbulent flow of nanofluid (Al2O3-distilled water) inside circular and elliptical (aspect ratio of 0.75) cross section tubes of identical circumference and tube surface area. Convection coefficient, pressure change, and fiction factor were compared at different Reynolds number (3,000-9,230) with different nanoparticles volume concentration (0.5%, 1.0%, and 1.5%). The results showed that Nusselt number increases with increasing Reynolds number and nanoparticle volume concentration. The pressure drops and friction factor of nanofluid are higher than the distilled water and are increasing as the volume concentration increases. Furthermore, the elliptical tube provided small increase in Nusselt number compared to that of circular cross sectional tube. However, the friction factor in the elliptical tube was slightly higher.

Experiments With a New Ribbed Blade Tip and Endwall Geometry on a High Pressure Turbine Blade

2015 ◽  
Author(s):  
Ralph J. Volino
Keyword(s):  
Total Pressure ◽  
Flow Direction ◽  
Pressure Change ◽  
Flow Area ◽  
Tip Leakage Vortex ◽  
Pressure Drops ◽  
Tip Leakage ◽  
Image Velocimetry ◽  
Passage Vortex ◽  
Blade Tip

A new blade tip and endwall geometry were studied experimentally. The blade tips and endwall included ribs directed in the pitchwise direction. The blade tip ribs fit between the endwall ribs, with a gap of 1.5% of axial chord between the top of each rib and the surface which it faced. Hence, a tip gap was maintained, but the tip flow area was divided into pitchwise directed channels. Experiments were conducted in a linear turbine cascade with wakes generated by moving upstream rods. Cases were documented both with and without wakes. The total pressure drop coefficient, ψ, through the cascade was measured in the endwall region. Velocity fields were acquired in two planes normal to the flow direction using particle image velocimetry (PIV). The rib geometry eliminated the strong tip leakage vortex present in comparison cases with flat and squealer tipped blades. The passage vortex was strengthened and moved farther from the endwall. In spite of the elimination of the tip leakage vortex, total pressure drops were higher with the ribs than with a squealer tip and the same tip gap. Additional experiments showed that dividing the leakage flow area into channels did not reduce the total pressure change, and the endwall ribs acted as roughness and increased ψ. Although the increase in ψ was a negative outcome for the cascade experiment, the elimination of the tip leakage vortex could have some benefit if its detrimental effect were reduced in downstream stages.

Pressure Loss Distribution in Three-Pass Rectangular Channels With Rib Turbulators

1989 ◽  
Vol 111 (4) ◽  
pp. 515-521 ◽  
Author(s):  
J. C. Han ◽  
P. Zhang
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Channel Width ◽  
Local Pressure ◽  
Number Range ◽  
Pressure Drops ◽  
Rectangular Channels ◽  
First Pass ◽  
Rib Turbulators ◽  
Channel Aspect Ratio

The present study investigated the combined effects of the flow channel aspect ratio, the rib turbulator configuration, and the sharp 180-deg turn on the distributions of the local pressure drop in three-pass rectangular channels for a Reynolds number range of 15,000 to 60,000. The channel aspect ratios (the channel width-to-height ratios W/H; ribs on the channel width, W, side) were 1, 1/2, and 1/4. The rib height-to-hydraulic diameter ratios (E/D) were 0.063, 0.047, and 0.039; the rib pitch-to-height ratios (P/E) were 5, 7.5, 10, and 15; the rib angles of attack (α) were 90, 60, and 45 deg. The results showed that the rib turbulators dominated the pressure drops in the first pass of the three-pass channel. The pressure drops in the two-pass and the three-pass channels were caused by both the rib turbulators and the sharp 180-deg turns. The differences of the pressure drops caused by the different rib configurations (rib angle, spacing, and height) were significant in the first pass. The differences, however, were diluted by the sharp 180-deg turns in the two-pass and the three-pass channels, and by the smaller channel aspect ratio (W/H changed from 1 to 1/4). The friction factor correlations for the first pass, the first two-pass, and the three-pass were obtained to account for the rib configuration, the channel aspect ratio, and the Reynolds number. The correlations can be used in the design of the turbine airfoil cooling passages.

A Reassessment of Metering Orifices for Low Reynolds Numbers

1965 ◽  
Vol 180 (1) ◽  
pp. 331-356 ◽  
Author(s):  
L. J. Kastner ◽  
J. C. McVeigh
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Flow Rate ◽  
Discharge Coefficient ◽  
Low Reynolds Number ◽  
Reynolds Numbers ◽  
Number Range ◽  
Low Reynolds Numbers ◽  
Discharge Coefficients ◽  
Low Reynolds

In view of the importance of accurate measurement of flow rate at low Reynolds numbers, there have been numerous attempts to develop metering devices having constant discharge coefficients in the range of pipe Reynolds numbers between about 3000 and 200 and even below this latter value, and some of these attempts have achieved a reasonable degrees of success. Nevertheless, some confusion exists regarding the dimensions and range of utility of certain designs which have been recommended and further information is necessary in order that the situation may be clarified. The aims of the present investigation, which is believed to be wider in scope than any published in this field in recent years, were to review and correlate existing knowledge and to make an experimental study of the properties of various types of orifice in the low range of Reynolds numbers. Arising from this it was hoped that a design might be evolved which not only had a satisfactorily constant discharge coefficient throughout the range but was also simple to manufacture and reproduce, even for small orifice diameters of the order of 0.5 in or less, and it is believed that some success in attaining this aim was achieved. The first section of the paper contains a review of previous investigations classified into three main groups. In the second part of the paper, experiments with various types of orifice plate are described and it is shown that a properly proportioned single-bevelled orifice has as good a performance in the low Reynolds number range as that of any of the more complicated shapes.

Experimental Study on the Effect of Localized Blockages on the Friction Factor of a 61-Pin Wire-Wrapped Bundle

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Mason Childs ◽  
Robert Muyshondt ◽  
Rodolfo Vaghetto ◽  
Duy Thien Nguyen ◽  
Yassin Hassan
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Flow Behavior ◽  
Fluid Pressure ◽  
Transition Flow ◽  
Flow Area ◽  
Number Range ◽  
Rod Bundle ◽  
Transition Flow Regime ◽  
Friction Factor Correlation

Abstract The thermal-hydraulic behavior of the flow in rod bundles has motivated numerous experimental and computational investigations. Previous studies have identified potential for accumulation of debris within the small subchannels of typical wire-wrapped assemblies with subsequent total or partial blockage of subchannel coolant flow. A test campaign was conducted to study the effects of localized blockages on the bundle averaged friction factor of a tightly packed wire-wrapped rod bundle. Blockages were installed within the bundle, and fluid pressure drop was measured across one wire pitch for a Reynolds number range of 500–17,200. The Darcy–Weisbach friction factor of the perturbed rod bundle geometry was compared with that of the unblocked bundle, as well as with the predictions of a well-established friction factor correlation. Differing effects based on blockage size and location for various flow regimes were studied. A number of conclusions can be made about the effects of the blockages on the friction factor, such as an increasing effect of the blockage on friction factor with an increase in Reynolds number, a change in flow behavior in the turbulent transition flow regime near Reynolds number 3000, differences in effect on friction factor for different types of subchannel blockage, and a nonlinear trend in friction factor variation with flow area impeded for edge subchannels. To this end, all data and quantified uncertainty produced in this study are made available for comparison and validation of advanced computational tools.

On Separation of a Divergent Flow at Moderate Reynolds Numbers

1976 ◽  
Vol 43 (2) ◽  
pp. 227-231 ◽  
Author(s):  
Yuji Matsuzaki ◽  
Yuan-Cheng Fung
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
Flow Separation ◽  
Reynolds Numbers ◽  
Pressure Differential ◽  
Divergence Angle ◽  
Number Range ◽  
Divergent Flow ◽  
Reynolds Number Range ◽  
Mean Pressure

Flow separation in a divergent channel was investigated in connection with problems of instability and oscillations in physiology at a Reynolds number range much smaller than that usually considered in engineering diffuser design. Experimental data on a divergent flow through a two-dimensional water tunnel in the Reynolds number range Re = 1000 to 6000 are presented. The quantities measured are flow rate, divergence angle, and mean pressure differential between two fixed points at the throat and downstream. In a lower range of divergence angle flow separation is characterized by a sharp decrease in the mean pressure differential when the flow rate is increased continuously and gradually; whereas recovery from separation is signaled by a discontinuous increase in pressure when the flow rate is decreased again. The critical Reynolds numbers for separation and reattachment are detectably different. Some discussion is given about flow separation in external and internal flows.

Stabilization of the Speed of the Hydraulic Motor Through Throttle Compensation for Volume Losses

2020 ◽  
Vol 26 (3) ◽  
pp. 126-130
Author(s):  
Krasimir Kalev
Keyword(s):  
Flow Rate ◽  
Hydraulic Drive ◽  
Pressure Change ◽  
Operating Conditions ◽  
Drive System ◽  
Inlet Pressure ◽  
Schematic Diagram ◽  
Hydraulic Characteristics ◽  
Hydraulic Motor ◽  
Flow Through

AbstractA schematic diagram of a hydraulic drive system is provided to stabilize the speed of the working body by compensating for volumetric losses in the hydraulic motor. The diagram shows the inclusion of an originally developed self-adjusting choke whose flow rate in the inlet pressure change range tends to reverse - with increasing pressure the flow through it decreases. Dependent on the hydraulic characteristics of the hydraulic motor and the specific operating conditions.

Sign in / Sign up

Export Citation Format

Share Document