Development of a Flowmeter for Sub Micro Liter per Second Order Unsteady Flow Rate Based on the Pressure Difference in a Capillary

An experimental study is performed to extract minute gas bubbles from liquids flowing in a simulated cardiopulmonary bypass system using a Venturi-aspirator unit. In other words, oxygen bubbles in oxygenated blood are simulated by air bubbles in water with AP30 (about same viscosity as whole blood). This study is intended to determine the feasibility of using a Venturi aspirator unit to extract minute gas bubbles from a simulated cardiopulmonary bypass system. Testing of the Venturi-type bubble extraction is carried out using three different test sections. Two Venturis are used, and a straight tube configuration is used as a control. The two Venturis are similar, with the exception that one has a longer inlet cone which causes the entering liquid to accelerate at a slower rate. Results are obtained for effectiveness of the aspirator unit as functions of total flow rate, extraction suction, suction pressure difference, and hydraulic head. It is concluded from the study that:(i) The effectiveness of the Venturis is typically between 90 and 100 percent. It increases with an increase in suction or suction pressure difference but decreases with an increase in total flow rate.(ii) The Venturi is most suitable for extraction of minute gas bubbles, especially for use with AP30 (whole blood), which yields substantially higher effectiveness than water.(iii) It is anticipated that a Venturi-aspirator unit can be superior to other bubble separation device as the cardiopulmonary bypass system for applications in extra corporeal blood oxygenation.

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Relationship Between Unsteady Flow, Pressure Fluctuations, and Noise in a Centrifugal Pump—Part B: Effects of Blade-Tongue Interactions

Journal of Fluids Engineering ◽

10.1115/1.2816814 ◽

1995 ◽

Vol 117 (1) ◽

pp. 30-35 ◽

Cited By ~ 67

Author(s):

S. Chu ◽

R. Dong ◽

J. Katz

Keyword(s):

Unsteady Flow ◽

Centrifugal Pump ◽

Pressure Difference ◽

Pressure Fluctuations ◽

Primary Sources ◽

Pressure Measurements ◽

Local Pressure ◽

Pressure Distributions ◽

Flow Pressure ◽

Tip Of The Tongue

Maps of pressure distributions computed using PDV data, combined with noise and local pressure measurements, are used for identifying primary sources of noise in a centrifugal pump. In the vicinity of the impeller pressure minima occur around the blade and near a vortex train generated as a result of non-uniform outflux from the impeller. The pressure everywhere also varies depending on the orientation of the impeller relative to the tongue. Noise peaks are generated when the pressure difference across the tongue is maximum, probably due to tongue oscillations, and when the wake impinges on the tip of the tongue.

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Determination of Permeability and Inertial Coefficients of Sintered Metal Porous Media Using an Isothermal Chamber

Applied Sciences ◽

10.3390/app8091670 ◽

2018 ◽

Vol 8 (9) ◽

pp. 1670 ◽

Cited By ~ 6

Author(s):

Wei Zhong ◽

Xiang Ji ◽

Chong Li ◽

Jiwen Fang ◽

Fanghua Liu

Keyword(s):

Porous Media ◽

Steady State ◽

Flow Rate ◽

Pressure Difference ◽

Testing Time ◽

Sintered Metal ◽

Steady State Method ◽

Volume Limit ◽

Inertial Coefficient

Sintered metal porous media are widely used in a broad range of industrial equipment. Generally, the flow properties in porous media are represented by an incompressible Darcy‒Forchheimer regime. This study uses a modified Forchheimer equation to represent the flow rate characteristics, which are then experimentally and theoretically investigated using a few samples of sintered metal porous media. The traditional steady-state method has a long testing time and considerable air consumption. With this in mind, a discharge method based on an isothermal chamber filled with copper wires is proposed to simultaneously determine the permeability and inertial coefficient. The flow rate discharged from the isothermal chamber is calculated by differentiating the measured pressure, and a paired dataset of pressure difference and flow rate is available. The theoretical representations of pressure difference versus flow rate show good agreement with the steady-state results. Finally, the volume limit of the isothermal chamber is addressed to ensure sufficient accuracy.

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A Numerical Analysis on the System Impedance in a Fan Cooling System

2003 International Electronic Packaging Technical Conference and Exhibition, Volume 2 ◽

10.1115/ipack2003-35121 ◽

2003 ◽

Cited By ~ 1

Author(s):

Dong-Il Kim ◽

Ki-So Bok ◽

Han-Bae Lee

Keyword(s):

Numerical Analysis ◽

Pressure Drop ◽

Flow Rate ◽

Pressure Difference ◽

Cooling System ◽

Computational Time ◽

Computational Domain ◽

Impedance Curve ◽

Fan Cooling ◽

Large Investment

To seek the fan operating point on a cooling system with fans, it is very important to determine the system impedance curve and it has been usually examined with the fan tester based on ASHRAE standard and AMCA standard. This leads to a large investment in time and cost, because it could not be executed until the system is made actually. Therefore it is necessary to predict the system impedance curve through numerical analysis so that we could reduce the measurement time and effort. This paper presents how the system impedance curve (pressure drop curve) is computed by CFD in substitute for experiment. In reverse order to the experimental principle of the fan tester, pressure difference was adopted first as inlet and outlet boundary conditions of the system and then flow rate was calculated. After determining the system impedance curve, it was compared with experimental results. Also the computational domain of the system was investigated to minimize computational time.

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The Effect of Boundary Layer Separation on Accuracy of Flow Measurement Using the Gibson Method

Volume 2: Fora, Parts A and B ◽

10.1115/fedsm2007-37564 ◽

2007 ◽

Cited By ~ 1

Author(s):

F. Z. Sierra ◽

A. Adamkowski ◽

G. Urquiza ◽

J. Kubiak ◽

H. Lara ◽

...

Keyword(s):

Boundary Layer ◽

Cross Section ◽

Flow Rate ◽

Pressure Difference ◽

Proper Time ◽

Effective Cross Section ◽

Boundary Layer Separation ◽

Water Hammer ◽

Time Interval ◽

Geometry Factor

The Gibson method utilizes the effect of water hammer phenomenon (hydraulic transients) in a pipeline for flow rate determination. The method consists in measuring a static pressure difference, which occurs between two cross-sections of the pipeline as a result of a temporal change of momentum from t0 to t1. This condition is induced when the water flow in the pipeline is stopped suddenly using a cut-off device. The flow rate is determined by integrating, within a proper time interval, the measured pressure difference change caused by the water hammer (inertia effect). However, several observations demonstrate that changes of pipeline geometry like diameter change, bifurcations, or direction shift by elbows may produce an effect on the computation of the flow rate. The paper focuses on this effect. Computational simulations have shown that the boundary layer separates when the flow faces sudden changes like these mentioned to above. The separation may reduce the effective cross section area of flow modifying a geometry factor involved into the computation of the flow rate. The remainder is directed to quantify the magnitude of such a factor under the influence of pipeline geometry changes. Results of numerical computations are discussed on the basis of how cross section reductions impact on the geometry factor magnitude and consequently on the mass flow rate.

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Unsteady Flow of Couple Stress Fluid Sandwiched Between Newtonian Fluids Through a Channel

Zeitschrift für Naturforschung A ◽

10.1515/zna-2017-0434 ◽

2018 ◽

Vol 73 (7) ◽

pp. 629-637

Author(s):

M. Devakar ◽

Ankush Raje ◽

Shubham Hande

Keyword(s):

Unsteady Flow ◽

Flow Rate ◽

Couple Stress ◽

Volume Flow Rate ◽

Volume Flow ◽

Newtonian Fluids ◽

Couple Stress Fluid ◽

Shear Stresses ◽

Fluid Velocities ◽

Fluid Parameters

AbstractThe aim of this article is to study the unsteady flow of immiscible couple stress fluid sandwiched between Newtonian fluids through a horizontal channel. The fluids and plates are initially at rest. At an instant of time, a constant pressure gradient is applied along the horizontal direction to generate the flow. The time-dependent partial differential equations are solved numerically using the finite difference method. The continuity of velocities and shear stresses at the fluid-fluid interfaces has been considered. The obtained results are displayed through graphs and are discussed for various fluid parameters pertaining the flow. The volume flow rate is also obtained numerically for diverse fluid parameters and is presented through a table. It is noticed that fluid velocities increased with time and reached a steady state after a certain time level. Also, the presence of couple stresses reduced the fluid velocities. Volume flow rate increased with Reynolds number and is reduced by increase of ratio of viscosities.

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