scholarly journals Analysis of Liquid Flow and Mixing in an Oscillatory Flow Reactor Provided with 2D Smooth Periodic Constrictions

2018 ◽  
Vol 4 (2) ◽  
pp. 1-15 ◽  
Author(s):  
F. Almeida ◽  
F. Rocha ◽  
A. Ferreira
Keyword(s):  
Flow Rate ◽  
Oscillatory Flow ◽  
Flow Reactor ◽  
Cross Sectional Area ◽  
Axial Dispersion ◽  
Mixing Efficiency ◽  
Sectional Area ◽  
Cross Sectional ◽  
Liquid Dispersion ◽  
Fluid Oscillation

In this research paper the residence time distribution (RTD) was monitored for a range of fluid oscillation, frequency, amplitude and flow rate in two oscillatory flow reactors (OFR) provided with 2D smooth periodic constrictions (2D-SPC) with different designs. It was studied the axial liquid dispersion using axial dispersion model and the mixing efficiency using tank-in-series model for continuous mode. Two cases, with and without fluid oscillation, were studied and determined the optimum conditions to ensure a close plug flow, an efficient mixing and a low axial liquid dispersion. The optimum operation conditions for the two 2D-SPC designs were found. Moreover, the effect of open cross-sectional area (a) on mixing and axial dispersion was also investigated. For low cross-sectional area values the mixing is higher. It was observed that fluid oscillation increases the mixing intensity even at lower flow rates, and the axial dispersion increases as the flow rate increases.

Accuracy and precision of MR velocity mapping in measurement of stenotic cross-sectional area, flow rate, and pressure gradient

1993 ◽  
Vol 3 (2) ◽  
pp. 433-437 ◽  
Author(s):  
Lars Søndergaard ◽  
Freddy Ståhlberg ◽  
Carsten Thomsen ◽  
Anders Stensgaard ◽  
Knud Lindvig ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Flow Rate ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Velocity Mapping ◽  
Cross Sectional ◽  
Accuracy And Precision

scholarly journals EFFECT OF OPERATING PARAMETERS UPON PERFORMANCE OF FUNCTIONAL SPECIMENS OF HIGH EXPANSION FOAM GENERATORS

2020 ◽  
Vol 1 (2) ◽  
pp. 14-21
Author(s):  
V Chuian ◽  
O Тymoshenko ◽  
A Hrachov
Keyword(s):  
Flow Rate ◽  
Cross Sectional Area ◽  
Solution Flow Rate ◽  
Operating Parameters ◽  
Spray Nozzle ◽  
Sectional Area ◽  
Solution Flow ◽  
Cross Sectional ◽  
Foam Expansion ◽  
Expansion Foam

The issues related to application of high expansion foam as flooding fire extinguishing agent as well as necessity of the development of high expansion foam generators in Ukraine are considered. Patent search concerning appropriate devices for generation of high expansion foam from foam solutions was conducted and it showed specific features of the components when generating high expansion foam. The results of the research of operating parameters of prototypes of high expansion foam generators of fan and ejection types are presented. For high expansion foam generators of fan type dependence of foam expansion, foam solution flow rate and amount of spent foam solution on the performance of the spray nozzle at different pressures and ratio of fan performance to the spray nozzle performance was established; the ratio of the cross-sectional area of the fan to the total area of the perforated holes in the foaming grid was studied, too. For high-expansion foam generators of the ejection type dependence of foam expansion, foam solution flow rate and amount of spent foam solution on the capacity of the spray nozzle unit at different pressures, foam solution flow rate to the total area of the holes in the foaming grid, and ratio of the cross-sectional area of the generator to the total area of the perforated holes of the foaming grid were studied. Functional models of the mentioned types of generators (both ejection (aspiration) one and generator equipped with fan (air blowing unit)) were developed, created and tested for the purpose of derivation of appropriate relations between their conditions of use and performance. At the same time, high expansion foam generators of fan type by their weight and size parameters are intended for use in the divisions of the Operative and Rescue Service of Civil Protection of the State Emergency Service of Ukraine as portable firefighting units. Such firefighting units are intended to be installed first of all on any state-of-the-art municipal fire engines equipped with autonomous AC generators. High expansion foam generators of ejection type are intended for use as firefighting units in foam firefighting systems of various facilities with fire hazard.

Viscous flow in collapsible tubes of slowly varying elliptical cross-section

1977 ◽  
Vol 81 (2) ◽  
pp. 273-294 ◽  
Author(s):  
Rosemary Wild ◽  
T. J. Pedley ◽  
D. S. Riley
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Transverse Velocity ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Collapsible Tube ◽  
Experimental Conditions ◽  
Cross Sectional ◽  
Elliptical Cross ◽  
Collapsible Tubes

This paper is concerned with steady flow in collapsible tubes, such as veins, at fairly low Reynolds number. Lubrication theory is used to calculate the velocity and pressure distribution in an elliptical tube whose cross-sectional area and eccentricity vary slowly and in a given way with longitudinal distance x. The transverse velocity field and the effect of inertia on the primary velocity and pressure distributions are calculated to first order in the relevant small parameter. The results of these calculations are combined with a relationship between transmural pressure and the cross-sectional area at any x which is close to that measured in (large) veins, and are used to predict the pressure and flow in a collapsible tube when a given distribution of external pressure is applied. Different relationships between the tube perimeter and cross-sectional area are examined. The theory is applied to an experiment in which a segment of collapsible tube is supported between two rigid segments, and squeezed; predictions of the relationship between the pressure drop and flow rate are made for various experimental conditions. In particular, when the resistance of the downstream rigid segment is held constant, a range of flow rates is found in which the pressure drop falls as the flow rate is raised; this agrees with experiment.

scholarly journals A Study on the Evaluation of Flow Distribution Evenness in Parallel-Arrayed Type Low Pressure Membrane Module Piping

2021 ◽  
Vol 43 (5) ◽  
pp. 325-334
Author(s):  
SeokHyun Jang ◽  
Sukmin Yoon ◽  
Si-Yeon Kim ◽  
Young-Joo Lee ◽  
No-Suk Park
Keyword(s):  
Flow Rate ◽  
Cfd Simulation ◽  
Branch Pipe ◽  
Low Pressure ◽  
Cross Sectional Area ◽  
Membrane Module ◽  
Sectional Area ◽  
Cross Sectional ◽  
Actual Measurement ◽  
The Cross

Objectives : In this study, the degree of uniformity of the flow rate flowing into each module is measured for the external pressure typed low-pressure membrane (microfiltration) filtration process that has been actually applied to water treatment, and computational fluid dynamics (CFD) technique is used to clarify the cause and effect.Methods : Mobile ultrasonic flow meter was used to measure the flow rate flowing from the membrane module pipe to each module, and the CFD technique was used to verify this.Results and Discussion : From the results of the actual measurement using ultrasonic flowmeter and CFD simulation, it was confirmed that the outflow flow rate from the branch pipe located at the end of the header pipe was three times higher than that of the branch pipe near the inlet. The reason was that the differential pressure generated between each membrane module was higher toward the end of the header pipe.Conclusions : When the ratio of the sum of the cross-sectional area of the branch pipe and the cross-sectional area of the header pipe was reduced by about 30 times, it was confirmed that the flow rate flowing from each branch pipe to the membrane module was almost equal. Also, If the flow in the header pipe is transitional or laminar (Reynolds No. is approximately 4,000 or less), the flowrate flowing from each branch pipe to the membrane module can be more even.

Maximal Expiratory Flow and Lung Volume Changes Associated with Exercise-Induced Asthma in Children and the Effect of Breathing a Low-Density Gas Mixture

1974 ◽  
Vol 46 (3) ◽  
pp. 317-329 ◽  
Author(s):  
S. R. Benatar ◽  
P. König
Keyword(s):  
Flow Rate ◽  
Vital Capacity ◽  
Forced Expiratory Volume ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Lung Volumes ◽  
Flow Rates ◽  
Before And After ◽  
Expiratory Flow

1. Lung volumes and maximum expiratory flow volume (MEFV) curves were measured before and after exercise and after a bronchodilator in eight asthmatic children. 2. Exercise produced significant changes in all volumes and flow rates measured, but the most sensitive measurement was of flow rate at an absolute volume in the terminal portion of the forced vital capacity. Of the more simply obtained measurements maximal flow at 50% of the exhaled vital capacity was the most sensitive, but reductions in forced expiratory volume at 1 s and peak flow rate were almost as marked. 3. The marked reductions in flow rates at low lung volumes after exercise were accompanied by large increases in residual volume and a reduction in the slope of the MEFV curve. These changes suggest functional closure of some lung units and an increase in the time-constant of emptying of other units. 4. The response of flow to breathing helium—oxygen (79:21, v/v) was assessed in the dilated state (before exercise or after bronchodilator) and the constricted state (after exercise) in five of the subjects. 5. An increase in density-dependence of flow rates at all lung volumes during constriction is evidence that, despite the reduction in flow rates, convective acceleration and turbulent flow constitute a greater proportion of the total upstream resistance after exercise than before exercise. The implication is that the cross-sectional area at equal pressure points (EPP) is smaller after exercise than before exercise. This could result from either bronchoconstriction with no change in the location of EPP, or from progression of the EPP further upstream to a region where loss of airways or reduction in their diameter has rendered the total cross-sectional area considerably smaller than under normal circumstances.

scholarly journals Drainage Performance of a Novel Catheter Designed to Reduce Drainage Catheter Failure

2020 ◽  
Vol 4 (01) ◽  
pp. 09-15
Author(s):  
Muath Bishawi ◽  
Bradley Feiger ◽  
Neel Kurupassery ◽  
Konstantinos Economopoulos ◽  
Paul Suhocki ◽  
...  
Keyword(s):  
Flow Rate ◽  
Cross Sectional Area ◽  
Surrounding Tissue ◽  
Sectional Area ◽  
Cross Sectional ◽  
Side Hole ◽  
Hole Shape ◽  
Drainage Catheter ◽  
Catheter Design ◽  
Flow Through

Abstract Objective Efficient flow of fluids through drainage/infusion catheters is affected by surrounding tissue, organ compression, and scar tissue development, limiting or completely obstructing flow through drainage holes. In this work, we introduce a novel three-dimensional (3D) drainage catheter with protected side holes to reduce flow blockages. We then compare its drainage performance to standard straight and pigtail catheters using computer-generated catheter designs and flow analysis software. Methods Drainage performance was computed as flow rate through the catheter for a given pressure differential. Each catheter contained drainage holes on the distal (insertion) end and a single outlet (hub) hole open to atmosphere. Computational fluid dynamics using ANSYS AIM 18.2 was used to simulate flow through the catheter and examine drainage performance based on variations to the following parameters: (1) side hole shape, (2) cross-sectional area of the catheters, (3) number of side holes, and (4) cross-sectional area of the side holes. Results Drainage through the newly introduced catheter in all simulations was nearly identical to standard pigtail and straight catheters. While working to optimize the 3D catheter design, we found that the changes in side hole shape and side hole cross-sectional area had little effect on the total flow rate through the catheters but had a large impact on flow rate through the side hole nearest to the hub (proximal hole). Additionally, the majority of flow in all catheters occurred at the most proximal 1 to 3 side holes closest to hub, with relatively little flow occurring at side holes more distally located (closest to insertion end). The 3D catheter demonstrated no changes in flow characteristics when the coiled segment was occluded, giving it an advantage over other catheter types when the catheter is compressed by surrounding tissue or other external obstruction. Conclusions The majority of fluid flow in catheters with a diameter of 4.67 mm (14 Fr) or smaller occurred at the most proximal 1 to 3 side holes. A novel 3D coiled catheter design can protect these proximal holes from external blockage while maintaining drainage performance compared with standard straight and pigtail catheters.

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