The effect of bend angle on pressure drop and flow behavior in a corrugated duct

2020 ◽  
Vol 231 (9) ◽  
pp. 3755-3777 ◽  
Author(s):  
Xuzhi Du ◽  
Anning Wei ◽  
Yuhao Fang ◽  
Zhigang Yang ◽  
Daniel Wei ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Flow Behavior ◽  
Bend Angle ◽  
Corrugated Duct

scholarly journals Research on the viscosity of stabilized emulsions in different pipe diameters using pressure drop and phase inversion

2021 ◽  
Author(s):  
Jose Plasencia ◽  
Nathanael Inkson ◽  
Ole Jørgen Nydal
Keyword(s):  
Pressure Drop ◽  
Salt Water ◽  
Flow Behavior ◽  
Turbulent Viscosity ◽  
Relative Viscosity ◽  
Cfd Modeling ◽  
Water Fraction ◽  
Water Fractions ◽  
Oil Emulsions ◽  
Mixture Velocity

AbstractThis paper reports experimental research on the flow behavior of oil-water surfactant stabilized emulsions in different pipe diameters along with theoretical and computational fluid dynamics (CFD) modeling of the relative viscosity and inversion properties. The pipe flow of emulsions was studied in turbulent and laminar conditions in four pipe diameters (16, 32, 60, and 90 mm) at different mixture velocities and increasing water fractions. Salt water (3.5% NaCl w/v, pH = 7.3) and a mineral oil premixed with a lipophilic surfactant (Exxsol D80 + 0.25% v/v of Span 80) were used as the test fluids. The formation of water-in-oil emulsions was observed from low water fractions up to the inversion point. After inversion, unstable water-in-oil in water multiple emulsions were observed under different flow regimes. These regimes depend on the mixture velocity and the local water fraction of the water-in-oil emulsion. The eddy turbulent viscosity calculated using an elliptic-blending k-ε model and the relative viscosity in combination act to explain the enhanced pressure drop observed in the experiments. The inversion process occurred at a constant water fraction (90%) and was triggered by an increase of mixture velocity. No drag reduction effect was detected for the water-in-oil emulsions obtained before inversion.

scholarly journals Effects of Nozzle Die Angle on Extruding Polymethylmethacrylate in Open-Source 3D Printing

2018 ◽  
Vol 15 (2) ◽  
pp. 663-665 ◽  
Author(s):  
Nor Aiman Sukindar ◽  
Mohd Khairol Anuar Mohd Ariffin ◽  
B.T. Hang Tuah Baharudin ◽  
Che Nor Aiza Jaafar ◽  
Mohd Idris Shah Ismail
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Drop ◽  
3D Printing ◽  
Open Source ◽  
Flow Behavior ◽  
Three Dimensional ◽  
3D Printer ◽  
Element Analysis ◽  
Factors Affecting

Open-source 3D printer has been widely used for fabricating three dimensional products. However, this technology has some drawbacks that need to be improved such as accuracy of the finished parts. One of the factors affecting the final product is the ability of the machine to extrude the material consistently, which is related to the flow behavior of the material inside the liquefier. This paper observes the pressure drop along the liquefier by manipulating the nozzle die angle from 80° to 170° using finite element analysis (FEA) for polymethylmethacrylate (PMMA) material. When the pressure drop along the liquefier is varied, the printed product also varies, thus providing less accuracy in the finished parts. Based on the FEA, it was found that 130° was the optimum die angle (convergent angle) for extruding PMMA material using open-source 3D printing.

Impact of Bifurcation Angle and Inlet Reynolds Number on Local Pressure Recovery in Biologically-Inspired Flow Networks

2017 ◽  
Author(s):  
Subhadeep Koner ◽  
David Calamas ◽  
Daniel Dannelley
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Wall Temperature ◽  
Flow Behavior ◽  
Flow Networks ◽  
Local Pressure ◽  
Biologically Inspired ◽  
Local Flow ◽  
Bifurcation Angle ◽  
Microscale Flow

This work computationally investigates local flow behavior in tree-like flow networks of varying scale, bifurcation angle, and inlet Reynolds number. The performance of the tree-like flow networks were evaluated based on pressure drop and wall temperature distributions. Microscale, mesoscale, and macroscale tree-like flow networks, composed of a range of symmetric bifurcation angles (15, 30, 45, 60, 75, and 90°) and subject to a range of inlet Reynolds numbers (1000, 2000, 4000, 10000, and 20000) were evaluated. Local pressure recoveries were evident at bifurcations, regardless of scale and bifurcation angle which may result in a lower total pressure drop when compared with traditional parallel channel networks. Similarly, wall temperature spikes were also present immediately following bifurcations due to flow separation and recirculation. The magnitude of the wall temperature increases at bifurcations was dependent upon both bifurcation angle and scale. When compared with mesoscale and macroscale flow networks, microscale flow networks resulted in the largest local pressure recoveries and the smallest temperature jumps at bifurcations. Thus, while biologically-inspired flow networks offer the same advantages at all scales, the greatest performance increases are achieved at microscale.

Compact Model of Slug Flow in Microchannels

2007 ◽  
Author(s):  
Dong Rip Kim ◽  
Jae-Mo Koo ◽  
Chen Fang ◽  
Julie E. Steinbrenner ◽  
Eon Soo Lee ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Liquid Water ◽  
Slug Flow ◽  
Flow Behavior ◽  
Contact Angles ◽  
Proton Exchange ◽  
Force Balance ◽  
Compact Model ◽  
Two Phase ◽  
Coverage Ratio

This paper presents a theoretical investigation of the movement of liquid droplets and slugs in hydrophobic microchannels and develops a compact model for this type of two-phase flow. This model is used in the prediction of pressure drop and liquid water coverage ratio, key parameters in the operation of Proton Exchange Membrane Fuel Cells (PEMFC), the primary motivation for this work. A semi-empirical, periodic-steady two-phase separated flow compact model is formulated to characterize the slug flow behavior. The momentum equation includes the effects of acceleration, friction and surface tension on the pressure drop. The model considers spatial changes in slug velocity through the use of a force balance formulation. The model uses a departure scheme that computes slug size and shape at entrainment. The steady state slug flow compact model is capable of predicting liquid water coverage ratio and pressure drop using liquid and gas flow rates and advancing/receding triple point contact angles as its only inputs. The results indicate that the pressure drop increases as the droplet formation frequency increases.

THE EFFECT OF DIFFERENT LOCATIONS OF TRACHEAL STENOSIS TO THE FLOW CHARACTERISTICS USING RECONSTRUCTED CT-SCANNED IMAGE

2012 ◽  
Vol 12 (04) ◽  
pp. 1250066 ◽  
Author(s):  
NASRUL HADI JOHARI ◽  
KAHAR OSMAN ◽  
ZULIAZURA MOHD SALLEH ◽  
JUHARA HARON ◽  
MOHAMMED RAFIQ ABDUL KADIR
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Tracheal Stenosis ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Flow Conditions ◽  
Inlet Flow Rate ◽  
Exhaled Air ◽  
Scanned Image ◽  
The Right

The presence of tracheal stenosis would alter the flow path of the inhaled and exhaled air and subsequently changed the flow behavior inside the trachea and main bronchi. Therefore, it was our aim to investigate and predict the changes of flow behavior along with the pressure distribution with respect to the presence of stenosis on the tracheal lumen. In this study, actual CT scan images were extracted for flow modeling purposes. The images were then reconstructed to mimic the effect of different stenosis locations. This method overcomes the problem of the absence of actual images for different tracheal stenosis locations. The flow was subjected to different breathing situations corresponding to low, moderate and rigorous activities. The results showed that for flow over the stenosis farthest from the bifurcation, the pressure drop was insignificant for all breathing situations. At the same time, the inlet flow rate at the bifurcation showed less air flows into the right lung as compared to healthy flow conditions. On the other hand, for the flow over stenosis closest to the bifurcation, the pressure drop near the bifurcation area was very significant at high flow rate.

Non-Newtonian Flow Behavior in Microchannels for Emulsion Formation

2006 ◽  
Author(s):  
Ravi Arora ◽  
Eric Daymo ◽  
Anna Lee Tonkovich ◽  
Laura Silva ◽  
Rick Stevenson ◽  
...  
Keyword(s):  
Shear Stress ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Power Law ◽  
Flow Behavior ◽  
Scale Up ◽  
High Wall Shear Stress ◽  
Shear Rates ◽  
Wall Shear ◽  
Low Shear

Emulsion formation within microchannels enables smaller mean droplet sizes for new commercial applications such as personal care, medical, and food products among others. When operated at a high flow rate per channel, the resulting emulsion mixture creates a high wall shear stress along the walls of the narrow microchannel. This high fluid-wall shear stress of continuous phase material past a dispersed phase, introduced through a permeable wall, enables the formation of small emulsion droplets — one drop at a time. A challenge to the scale-up of this technology has been to understand the behavior of non-Newtonian fluids under high wall shear stress. A further complication has been the change in fluid properties with composition along the length of the microchannel as the emulsion is formed. Many of the predictive models for non-Newtonian emulsion fluids were derived at low shear rates and have shown excellent agreement between predictions and experiments. The power law relationship for non-Newtonian emulsions obtained at low shear rates breaks down under the high shear environment created by high throughputs in small microchannels. The small dimensions create higher velocity gradients at the wall, resulting in larger apparent viscosity. Extrapolation of the power law obtained in low shear environment may lead to under-predictions of pressure drop in microchannels. This work describes the results of a shear-thinning fluid that generates larger pressure drop in a high-wall shear stress microchannel environment than predicted from traditional correlations.

Effect of Vertical Fractures on Reservoir Behavior--Compressible-Fluid Case

10.2118/98-pa ◽  
1962 ◽  
Vol 2 (02) ◽  
pp. 87-94 ◽  
Author(s):  
M. Prats ◽  
P. Hazebroek ◽  
W.R. Strickler
Keyword(s):  
Pressure Drop ◽  
Incompressible Fluid ◽  
Production Rate ◽  
Flow Behavior ◽  
Fractured Reservoirs ◽  
Fractured Reservoir ◽  
Vertical Fracture ◽  
Fracture Length ◽  
Production Behavior ◽  
The One

Abstract The pressure and production behavior of a homogeneous cylindrical reservoir producing a single fluid through a centrally located vertical fracture of limited lateral extent was determined by using mathematical methods to solve the appropriate differential equation. It is assumed that there is no pressure drop within the fracture - that is, that the fracture capacity is infinite. It was found that the production-rate decline of such a reservoir is constant (except for very early times) when the flowing bottom-hole pressure remains constant. The production-rate decline increases as the fracture length increases. Thus, the lateral extent of fractures can be determined from the production-rate declines before and after fracturing or from the decline rate after fracturing when the properties of the formation and fluids are known. The production behavior over most of the productive life of such a fractured reservoir can be represented by an equivalent radial-flow reservoir of equal volume. The effective well radius of this equivalent reservoir is equal to one-fourth the total fracture length (within 7 per cent); the outer radius of this equivalent reservoir is very nearly equal (within 3.5 per cent) to that of the drainage radius of the fractured well. The effective well radius of a reservoir producing at semisteady state is also very nearly equal to one-fourth the total fracture length. It thus appears that the behavior of vertically fractured reservoirs can be interpreted in terms of simple radial-flow reservoirs of large wellbore. Introduction An earlier report has considered the effect of a vertical fracture on a reservoir producing an incompressible fluid. That investigation of the fractured reservoir producing an incompressible fluid was started because of its simplicity. Thus, pertinent behavior of fractured reservoirs was obtained at an early date, while experience was being gained of value in the solution of more complicated fracture problems. One of these more complicated problems, and the one discussed in this report, considers the effect of a compressible fluid (instead of incompressible fluids) on the production behavior of a fractured reservoir. In the incompressible-fluid work mentioned, it was shown that the production rate after fracturing could be described exactly by an effective well radius equal to one-fourth the fracture length whenever the pressure drop in the fracture was negligible. Because of the simplification in interpretation, it is a matter of much interest to determine whether the production behavior of reservoirs producing a compressible liquid could be described in terms of an effective well radius which remains essentially constant over the producing life of the field. The details of the mathematical investigation are given in the Appendixes. IDEALIZATION AND DESCRIPTION OF THE FRACTURED SYSTEM It is assumed that a horizontal oil-producing layer of constant thickness and of uniform porosity and permeability is bounded above and below by impermeable strata. The reservoir has an impermeable circular cylindrical outer boundary of radius r e. The fracture system is represented by a single, plane, vertical fracture of limited radial extent, bounded by the impermeable matrix above and below the producing layer (reservoir). It is assumed that there is no pressure drop in the fracture due to fluid flow. Fig. 1 indicates the general three-dimensional geometry of the fractured reservoir just described. When gravity effects are neglected, the flow behavior in the reservoir is independent of the vertical position in the oil sand. Thus, the flow behavior in the fractured reservoir is described by the two-dimensional flow behavior in a horizontal cross-section of the reservoir, such as the one shown in Fig. 2. SPEJ P. 87^

scholarly journals Influence of wall waviness on friction and pressure drop in channels

1981 ◽  
Vol 4 (4) ◽  
pp. 805-818 ◽  
Author(s):  
K. Vajravelu ◽  
Ali H. Nayfeh
Keyword(s):  
Pressure Drop ◽  
Flow Behavior ◽  
Reynolds Numbers ◽  
Wavy Wall ◽  
Governing Equations ◽  
Short Waves ◽  
Gradient Parameter ◽  
Arbitrary Amplitude ◽  
Wavy Channels ◽  
Good Agreement

An attention has been given to investigate the flow behavior of an incompressible viscous fluid confined in horizontal wavy channels and set in motion due to the movement of the upper wall and the pressure differences. The governing equations have been solved analytically as well as numerically subject to the relevant boundary conditions by assuming that the solution consists of two parts: a mean part and a disturbance or perturbed part. For small and moderate Reynolds numbers, the analytical solution for the perturbed part has been found to be in good agreement with the numerical one. The effects of Reynolds number, the pressure gradient parameter, and the undulation wavenumber on friction and pressure drop are found to be quite significant. In addition to the flow behavior for both long and short waves and for large Reynolds numbers, the effect of the wall waviness on friction and pressure drop has been examined for any arbitrary amplitude of the wavy wall.

Delta Winglet Pairs in the Core of a Pipe and its Effect on Heat Transfer and Flow

2019 ◽  
Author(s):  
Md. Islam ◽  
Z. Chong ◽  
Md. Alam
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Friction Factor ◽  
Flow Behavior ◽  
Experimental Results ◽  
Vortex Generators ◽  
Experimental Investigations ◽  
Longitudinal Vortices ◽  
The Core ◽  
Delta Winglet

Abstract Vortex generators/turbulent promoters generate the longitudinal vortices which introduce the better mixing of the fluid with fluid circulation and enhance heat transfer. In this research, experimental investigations have been carried out to study the effect of delta winglet vortex generator (DWVG) in the core of the pipe on heat transfer and flow behavior. In this experiment, two pairs of delta winglet vortex generators (DWVG) were printed on the upside and downside of the thin plate using 3D printing technology in a ring and then placed in the core of the pipe to generate longitudinal vortices. Middle plate was very thin. The effect of heights (H = 5mm, 10mm, 15mm and 20mm) of DWVG for 10° angle of attack and 15mm spacing between leading edges of VG pairs on heat transfer and pressure drop was studied. The experiments were conducted for a fully developed turbulent flow of air in the range of Reynolds numbers (Re) 5000–25000. The influence of the DWVGs on heat transfer and pressure drop was investigated in terms of the Nusselt number (Nu) and friction factor (f). The experimental results indicate that DWVG in the core of the tube results in a considerable increase in Nu with some pressure penalty. It is found that DWVG increase Nu considerably only when H is over 10mm. Nu increases with Re and H. Friction factor decreases with Re but increase with H. The thermal performance enhancement (TPE) was noticed decreasing with Re. TPE could be obtain up to 1 only when the height is over 10mm for Re ≤ 7500. The experimental results show that the DWVG in the core of the pipe is not a good option to enhance the heat transfer at a higher Re.

Prediction of Flow Path Pressure Drops in Curved Galleries for Additively Manufactured Hydraulic Manifolds

2021 ◽  
Author(s):  
L. D. Hashan Peiris ◽  
Andrew Plummer ◽  
Jens Roesner ◽  
Vimal Dhokia ◽  
Wesley Essink
Keyword(s):  
Pressure Drop ◽  
Flow Path ◽  
Bend Angle ◽  
Flow Paths ◽  
Pressure Drops ◽  
Form Pressure ◽  
Manifold Optimization ◽  
Computational Fluid Dynamics Cfd ◽  
Sharp Corners ◽  
Analytical Expressions

Abstract Hydraulic manifolds are traditionally manufactured using externally drilled intersecting galleries. This results in undesirable artefacts in the flow path such as sharp corners, and dead oil volumes, and requires additional plugs to blank redundant holes. These artefacts affect flow separation, aggravate pressure-drop and reduce hydraulic stiffness. Recent advancements in additive manufacturing (AM) technology have enabled the development of additively manufactured components which provide greater freedom in channel design and routing. Galleries can provide flow paths which are smoothly curved in 3 dimensions. AM manifold geometry can be optimized to reduce size and weight. In this research, analytical expressions are sought to approximate pressure drops in complex curved flow paths, which can subsequently be used for manifold optimization. The curved flow paths are defined by polynomial splines which are then fragmented into a series of segments each defined by a bend angle and bend radius. This paper uses approximations to Computational Fluid Dynamics (CFD) results to form pressure-drop models over a range of segment bend radii and angles. These models are then used to predict the pressure drops for curved galleries used in AM manifolds. The method is applied to four example curved galleries, and provides a reasonably accurate pressure-drop prediction in each case.

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