Investigation of Flow Regime Transitions in Large-Diameter Inclined Pipes

1999 ◽  
Vol 121 (2) ◽  
pp. 91-95 ◽  
Author(s):  
J. Y. Cai ◽  
M. Gopal ◽  
W. P. Jepson
Keyword(s):  
Flow Regime ◽  
Gas Flow ◽  
Liquid Velocity ◽  
Large Diameter ◽  
Gas Velocity ◽  
Low Viscosity ◽  
Flow Regime Transition ◽  
System Pressure ◽  
Water Cut ◽  
Inclined Pipes

Multiphase oil/water/gas flow regime transition studies are carried out in a 10-cm i.d., 18-m long pipe at inclinations of ±2 deg at system pressures between 0 to 0.79 MPa. The results are compared to those of other researchers, and the effects of pressure, inclination, and liquid viscosity are shown. The water cut of the liquid has some effects on the transition from stratified to slug flow. Increasing the water cut results in the transition occurring at higher liquid velocity at the same gas velocity. Water cut has little effect on the slug/annular transition for low viscosity oil used. The system pressure has a moderate effect on the transition from stratified to slug and slug to annular. For the transition from stratified to slug, increasing the system pressure requires higher liquid velocity. The transition from slug to annular occurs at lower liquid velocity with increasing the system pressures. The inclination of the pipe has little effect on the transition from slug to annular flow. Increasing the inclination causes the transition to occur at approximately the same gas velocity at the same liquid velocity. The experimental results show a good agreement with Wilkens’ model.

Simulation of mechanically stirred two-phase liquid-gas flow

1986 ◽  
Vol 51 (5) ◽  
pp. 1001-1015 ◽  
Author(s):  
Ivan Fořt ◽  
Vladimír Rogalewicz ◽  
Miroslav Richter
Keyword(s):  
Spatial Distribution ◽  
Velocity Field ◽  
Gas Flow ◽  
Liquid Velocity ◽  
Model Parameters ◽  
Two Phase ◽  
Mean Velocity ◽  
Rushton Turbine ◽  
Low Viscosity ◽  
Volumetric Gas Flow Rate

The study describes simulation of the motion of bubbles in gas, dispersed by a mechanical impeller in a turbulent low-viscosity liquid flow. The model employs the Monte Carlo method and it is based both on the knowledge of the mean velocity field of mixed liquid (mean motion) and of the spatial distribution of turbulence intensity ( fluctuating motion) in the investigated system - a cylindrical tank with radial baffles at the wall and with a standard (Rushton) turbine impeller in the vessel axis. Motion of the liquid is then superimposed with that of the bubbles in a still environment (ascending motion). The computation of the simulation includes determination of the spatial distribution of the gas holds-up (volumetric concentrations) in the agitated charge as well as of the total gas hold-up system depending on the impeller size and its frequency of revolutions, on the volumetric gas flow rate and the physical properties of gas and liquid. As model parameters, both liquid velocity field and normal gas bubbles distribution characteristics are considered, assuming that the bubbles in the system do not coalesce.

Effect of Drag-Reducing Agent on Slug Characteristics in Multiphase Flow in Inclined Pipes

1999 ◽  
Vol 121 (2) ◽  
pp. 86-90 ◽  
Author(s):  
C. Kang ◽  
W. P. Jepson ◽  
M. Gopal
Keyword(s):  
Pressure Drop ◽  
Multiphase Flow ◽  
Liquid Film ◽  
Froude Number ◽  
Liquid Velocity ◽  
Translational Velocity ◽  
Gas Velocity ◽  
Superficial Gas Velocity ◽  
Inclined Pipes ◽  
Superficial Liquid Velocity

The effect of drag-reducing agent (DRA) on multiphase flow in upward and downward inclined pipes has been studied. The effect of DRA on pressure drop and slug characteristics such as slug translational velocity, the height of the liquid film, slug frequency, and Froude number have been determined. Experiments were performed in 10-cm i.d., 18-m long plexiglass pipes at inclinations of 2 and 15 deg for 50 percent oil-50 percent water-gas. The DRA effect was examined for concentrations ranging from 0 to 50 ppm. Studies were done for superficial liquid velocities between 0.5 and 3 m/s and superficial gas velocities between 2 and 10 m/s. The results indicate that the DRA was effective in reducing the pressure drop for both upflow and downflow in inclined pipes. Pressure gradient reduction of up to 92 percent for stratified flow with a concentration of 50 ppm DRA was achieved in ±2 deg downward inclined flow. The effectiveness of DRA for slug flow was 67 percent at a superficial liquid velocity of 0.5 m/s and superficial gas velocity of 2 m/s in 15 deg upward inclined pipes. Slug translational velocity does not change with DRA concentrations. The slug frequency decreases from 68 to 54 slugs/min at superficial liquid velocity of 1 m/s and superficial gas velocity of 4 m/s in 15 deg upward inclined pipes as the concentration of 50 ppm was added. The height of the liquid film decreased with the addition of DRA, which leads to an increase in Froude number.

Effect of Surface Wettability and Gas/Liquid Velocity Ratio on Microscale Two-Phase Flow Patterns

2016 ◽  
Author(s):  
Hongxia Li ◽  
Charles C. Okaeme ◽  
Weilin Yang ◽  
TieJun Zhang
Keyword(s):  
Multiphase Flow ◽  
Flow Regime ◽  
Two Phase Flow ◽  
Liquid Velocity ◽  
Velocity Ratio ◽  
Surface Wettability ◽  
Phase Flow ◽  
Regime Transition ◽  
Two Phase ◽  
Flow Regime Transition

Predicting and controlling the flow regime transition of multiphase fluids in microchannels is essential for various energy applications, such as flow boiling, de-emulsification and oil recovery processes. This in turn requires a better understanding of multiphase flow behaviors in microchannels with various channel surface wettability, fluid interfacial tension and flow rates. In this paper, experiments and Lattice Boltzmann method (LBM) simulations are carried out to study complicated multiphase flow at micro or meso scales. With the Shan-Chen multiphase LBM model, the flow pattern transitions of adiabatic two phase flow in a microchannel were investigated. The effects of surface wettability and liquid/gas velocity ratio on the flow regime transition were further studied. A series of two-phase flow experiments were conducted on a PDMS microfluidic device under different gas/oil velocity ratios. Under various surface wettability conditions, our simulation results agree well with the flow visualization experiments equipped with a high speed camera (HSC). Our finding shows that the cross-section meniscus curve width, corresponding to the shadow in the HSC photo, increases with decreasing contact angle, which was confirmed by the simulated liquid/gas distribution. Besides the influence of surface wettability, the role of gas/liquid velocity ratio on two-phase flow regime transition was discussed in detail. The proposed approach paves the way to probe complicated physics of multiphase flows in microporous media.

Experimental Study of Flow Regime Map in 5×5 Rod Bundle

2017 ◽  
Author(s):  
Hang Liu ◽  
Quanyao Ren ◽  
Liangming Pan ◽  
Takashi Hibiki ◽  
Wenxiong Zhou ◽  
...  
Keyword(s):  
Flow Regime ◽  
Gas Flow ◽  
Regime Transition ◽  
Rod Bundles ◽  
Flow Rates ◽  
Flow Regime Transition ◽  
Transition Criteria ◽  
Measured Flow ◽  
Regime Map ◽  
Flow Regime Map

In relation to development of the flow regime criteria for rod bundles, this paper provides an experimental flow regime map and compares the experimental map with the existing flow regime transition criteria for vertical rod bundles so far. An experiment of vertical adiabatic air-water flow was conducted under an atmosphere pressure conditions. The experiment facility was composed of 5×5 rod arranged on a square pitch in a square shell with 9.5 mm outside diameter and 12.6 mm pitch. A total of 242 data sets were acquired consisting of superficial gas flow rates, 0.02–8.69 m/s, and superficial liquid flow rates, 0.02–2.13 m/s. A new flow regime map was obtained and the flow regime transition model for rod bundles was validated by the measured flow regime map. A fairly good agreement with some discrepancies has been obtained between the existing flow regime transition criteria and measured flow regime maps for rod bundles.

Flow Regime Identification in Large Diameter Pipe

2008 ◽  
Author(s):  
Pravin Sawant ◽  
Joshua Schelegel ◽  
Sidharth Paranjape ◽  
Basar Ozar ◽  
Takashi Hibiki ◽  
...  
Keyword(s):  
Neural Network ◽  
Flow Regime ◽  
Void Fraction ◽  
Test Section ◽  
Liquid Velocity ◽  
Bubbly Flow ◽  
Large Diameter ◽  
Cumulative Probability ◽  
Two Phase ◽  
Self Organized

Air-water vertical two-phase flow experiments were performed in a 0.15 m diameter and 4.4 m long test section. Superficial liquid velocity was varied from 0.05 m/s to 2.0 m/s and superficial gas velocity was varied to obtain the area averaged void fraction range of 0.1 to 0.7. Exit pressure was close to the atmospheric pressure. In order to study the development of flow structure over the length of test section, area averaged void fraction was measured using impedance meters at four different measuring ports. Pressure drop was also measured between these ports. Since the temporal variation of void fraction signal obtained from the impedance meter and its distribution are characteristic of the flow regime, a Cumulative Probability Distribution Function (CPDF) of the void fraction signal was utilized for the identification of flow regime at each port. The CPDFs of the impedance probe void fraction signal were supplied as an input to the Kohonen Self Organized neural network or the Self Organized Map (SOM) for the identification of the patterns by employing self organized neural network technique. The three flow regimes identified by the neural network are subjectively named as bubbly flow, cap-bubbly flow and cap-turbulent flow.

scholarly journals Influence of center gas supply device on gas–solid flow in COREX shaft furnace through DEM–CFD model

2020 ◽  
Vol 18 (5-6) ◽  
Author(s):  
Heng Zhou ◽  
Shuyu Wang ◽  
Binbin Du ◽  
Mingyin Kou ◽  
Zhiyong Tang ◽  
...  
Keyword(s):  
Gas Flow ◽  
Shaft Furnace ◽  
Middle Zone ◽  
Cfd Model ◽  
Gas Velocity ◽  
Gas Distribution ◽  
Particle Segregation ◽  
Solid Flow ◽  
Corex Shaft Furnace ◽  
Gas Supply

AbstractIn order to develop the central gas flow in COREX shaft furnace, a new installment of center gas supply device (CGD) is designed. In this work, a coupled DEM–CFD model was employed to study the influence of CGD on gas–solid flow in COREX shaft furnace. The particle descending velocity, particle segregation behaviour, void distribution and gas distribution were investigated. The results show that the CGD affects the particles descending velocity remarkably as the burden falling down to the slot. Particle segregation can be observed under the inverse ‘V’ burden profile, and the influence of CGD on the particle segregation is unobvious on the whole, which causes the result that the voidage is slightly changed. Although the effect of CGD on solid flow is not significant, the gas flow in shaft furnace has an obvious change. Compared with the condition without CGD, in the case with CGD, the gas velocity is improved significantly, especially in the middle zone of the furnace, which further promotes the center gas distribution. Meanwhile, the pressure drop in the furnace with the installation of CGD is increased partly.

New Gel Aggregates To Improve Sweep Efficiency During Waterflooding

2011 ◽  
Vol 14 (01) ◽  
pp. 120-128 ◽  
Author(s):  
Guanglun Lei ◽  
Lingling Li ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Low Cost ◽  
Oil Production ◽  
High Water ◽  
Resistance Factor ◽  
Water Production ◽  
Sweep Efficiency ◽  
Low Viscosity ◽  
Productivity Decline ◽  
High Water Cut ◽  
Water Cut

Summary A common problem for oil production is excessive water production, which can lead to rapid productivity decline and significant increases in operating costs. The result is often a premature shut-in of wells because production has become uneconomical. In water injectors, the injection profiles are uneven and, as a result, large amounts of oil are left behind the water front. Many chemical systems have been used to control water production and improve recovery from reservoirs with high water cut. Inorganic gels have low viscosity and can be pumped using typical field mixing and injection equipment. Polymer or crosslinked gels, especially polyacrylamide-based systems, are mainly used because of their relatively low cost and their supposed selectivity. In this paper, microspheres (5–30 μm) were synthesized using acrylamide monomers crosslinked with an organic crosslinker. They can be suspended in water and can be pumped in sandstone formations. They can plug some of the pore throats and, thus, force injected water to change its direction and increase the sweep efficiency. A high-pressure/high-temperature (HP/HT) rheometer was used to measure G (elastic modulus) and G" (viscous modulus) of these aggregates. Experimental results indicate that these microspheres are stable in solutions with 20,000 ppm NaCl at 175°F. They can expand up to five times their original size in deionized water and show good elasticity. The results of sandpack tests show that the microspheres can flow through cores with permeability greater than 500 md and can increase the resistance factor by eight to 25 times and the residual resistance factor by nine times. The addition of microspheres to polymer solutions increased the resistance factor beyond that obtained with the polymer solution alone. Field data using microspheres showed significant improvements in the injection profile and enhancements in oil production.

Low Bond Number Two-Phase Flow Regime Transition from Slug to Annular Wavy Flow in a Microchannel

2003 ◽  
Vol 125 (4) ◽  
pp. 544-544 ◽  
Author(s):  
Sang Young Son ◽  
Jeffrey S. Allen ◽  
Kenneth O. Kihm
Keyword(s):  
Flow Regime ◽  
Two Phase Flow ◽  
Bond Number ◽  
Phase Flow ◽  
Regime Transition ◽  
Two Phase ◽  
Flow Regime Transition

scholarly journals Research and Development of a 3D Jet Printer for High-Viscosity Molten Liquids

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 554
Author(s):  
Yang Yang ◽  
Shoudong Gu ◽  
Jianfang Liu ◽  
Hongyu Tian ◽  
Qingqing Lv
Keyword(s):  
Liquid Velocity ◽  
New Technology ◽  
Droplet Diameter ◽  
Average Diameter ◽  
High Viscosity ◽  
Taper Angle ◽  
Voltage Difference ◽  
Low Viscosity ◽  
Cooling Mechanism ◽  
Molten Liquid

Micro-droplet jetting manufacture is a new 3D printing technology developed in recent years. Presently, this new technology mainly aims at ejecting a low-viscosity medium. Therefore, a device for ejecting high-viscosity molten liquid is designed by analyzing the injection principle of high-viscosity molten liquid. Initially, the cooling mechanism is designed to overcome the defect that the piezoelectric stacks cannot operate in high-temperature conditions. Thereafter, the mathematical model of the liquid velocity in the nozzle is derived, and the factors influencing injection are verified by Fluent. Subsequently, a prototype of the jet printer is fabricated, and the needle velocity is tested by the laser micrometer; the relationship between voltage difference and the needle velocity is also obtained. The experimental results matched the theoretical model well, showing that the voltage difference, needle radius, nozzle diameter, and taper angle are closely related to the injection performance of the 3D jet printer. By using a needle with a radius of 0.4 mm, a nozzle with a diameter of 50 μm, a taper angle of 90°, a supply pressure of 0.05 Mpa, and a voltage difference of 98 V, a molten liquid with a viscosity of 8000 cps can be ejected with a minimum average diameter of 275 μm, and the variation of the droplet diameter is within ±3.8%.

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