Submerged Gas Injection in Microgravity

2002 ◽  
Author(s):  
J. Carrera ◽  
R. N. Parthasarathy ◽  
S. R. Gollahalli
Keyword(s):  
Surface Tension ◽  
Weber Number ◽  
Gas Flow ◽  
Capillary Tube ◽  
Bubble Formation ◽  
Gas Injection ◽  
Flow Regimes ◽  
Flowing Liquid ◽  
Flow Rates ◽  
Reduced Surface

The effects of buoyancy on the flow regimes of submerged gas injection were studied in this investigation. A capillary tube submerged in water was used for gas injection in microgravity and terrestrial conditions, and the resulting flow regimes and bubble sizes were documented. The effects of liquid co-flow and reduced surface tension were also analyzed. Under reduced gravity, three flow regimes were observed over the range of conditions tested. At low gas flow rates, the bubbles did not detach from the injector, forming an interconnected bubble cluster that adhered to the injector. Single bubbles started detaching and moving away from the injector when the Weber number reached a value around 3. At gas flow rates corresponding to a Weber number value of 10, the bubble coalescence regime was observed near the injector. It was found that the absence of buoyancy prevented the formation of the jetting regime. For all gas throughputs, the co-flowing liquid aided the detachment of the bubbles, resulting in the generation of more uniform bubbles than in quiescent liquids. The presence of co-flow resulted in a smaller bubble size accompanied by an increased frequency of bubble formation. Reduced surface tension produced a similar effect, resulting in smaller bubbles.

The Effect of Surfactants on Vertical Air/Water Flow for Prevention of Liquid Loading

SPE Journal ◽  
2016 ◽  
Vol 21 (02) ◽  
pp. 488-500 ◽  
Author(s):  
A. T. van Nimwegen ◽  
L. M. Portela ◽  
R. A. Henkes
Keyword(s):  
Surface Tension ◽  
Pressure Gradient ◽  
Water Flow ◽  
Annular Flow ◽  
Surfactant Concentration ◽  
Gas Flow ◽  
Liquid Loading ◽  
Dynamic Surface ◽  
Flow Rates ◽  
Churn Flow

Summary From field experience in the gas industry, it is known that injecting surfactants at the bottom of a gas well can prevent liquid loading. To better understand how the selection of the surfactant influences the deliquification performance, laboratory experiments of air/water flow at atmospheric conditions were performed, in which two different surfactants (a pure surfactant, sodium dodecyl sulfate, and a commercial surfactant blend) were added to the water. In the experiments, a high-speed camera was used to visualize the flow, and pressure-gradient measurements were performed. Both surfactants increase the pressure gradient at high gas-flow rates and decrease the pressure gradient at low gas-flow rates. The minimum in the pressure gradient moves to lower gas-flow rates with increasing surfactant concentration. This is related to the transition between annular flow and churn flow, which is shifted to lower gas-flow rates because of the formation of an almost stagnant foam substrate at the wall of the pipe. At high surfactant concentration, it appears that the churn flow regime is no longer present at all and that there is a direct transition from annular flow to slug flow. The results also show that the critical micelle concentration, the equilibrium surface tension, the dynamic surface tension, and the surface elasticity are poor predictors of the effect of the surfactant on the flow.

Computational Modeling of Adiabatic Bubble Growth Dynamics From Submerged Capillary-Tube Orifices in Aqueous Solutions of Surfactants

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Sanjivan Manoharan ◽  
Anirudh M. Deodhar ◽  
Raj M. Manglik ◽  
Milind A. Jog
Keyword(s):  
Surface Tension ◽  
Interfacial Tension ◽  
Capillary Tube ◽  
Pure Water ◽  
Growth Dynamics ◽  
Interface Region ◽  
Pure Liquid ◽  
Flow Rates ◽  
Air Interface ◽  
Adsorption Desorption

The growth dynamics of isolated gas bubbles from a submerged capillary-tube orifice in a pool of an aqueous surfactant (sodium dodecyl sulfate or SDS) solution is computationally investigated. The governing equations for surfactant mass transport in the bulk liquid and interfacial adsorption–desorption are solved simultaneously with the Navier–Stokes equations, employing the volume-of-fluid (VOF) technique to track the deforming liquid–air interface. The VOF method tends to spread the liquid–air interface over two to three computational cells, creating an interface region with finite thickness. A new numerical treatment is developed to determine the surfactant transport and adsorption/desorption in the interface region. From the variation of the surfactant interfacial concentration, the spatio-temporal variation in interfacial tension is determined and the shape of the growing bubble is predicted. To validate the numerical model, experimental measurements of bubble shape and size are carried out using high speed videography. Because of the decrease in surface tension with surface age, bubble departure diameters in SDS–water solutions are smaller than those obtained in pure water, and they are a function of bubble frequency. At higher air-flow rates (smaller surface age), the bubble departure diameters tend toward those in pure water, whereas at low flow rates (larger surface age), they are significantly smaller than those in water and are closer in size to those in a pure liquid having surface tension equal to the equilibrium value in SDS solution. Furthermore, the nonuniform surfactant adsorption–desorption at the evolving interface results in variation in interfacial tension around the bubbles, and thus their shapes in surfactant solution are different from those in a pure liquid.

Slug Bubble Formation in a Co-Flowing Liquid in a Capillary Tube

2007 ◽  
Vol 40 (11) ◽  
pp. 913-919 ◽  
Author(s):  
Takashi Goshima ◽  
Koichi Terasaka
Keyword(s):  
Capillary Tube ◽  
Bubble Formation ◽  
Flowing Liquid

Simultaneous gas and water flow in a damage-susceptible bedded argillaceous rock

2015 ◽  
Vol 52 (1) ◽  
pp. 18-32 ◽  
Author(s):  
T.S. Nguyen ◽  
A.D. Le
Keyword(s):  
Water Flow ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Gas Injection ◽  
Injection Pressure ◽  
Opalinus Clay ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Inherent Anisotropy

A mathematical model that couples the governing and constitutive equations of two-phase flow and mechanical equilibrium has been developed to simulate gas injection tests for both laboratory- and field-scale experiments. The model takes into consideration the inherent anisotropy of sedimentary rocks due to bedding by including an anisotropic elastoplastic model for the mechanical process and using an anisotropic permeability tensor for the flow processes for both water and gas. The gas and water flow rates are assumed to follow Darcy’s law. The relative permeability of each phase and their respective degrees of saturation are represented by the Van Genuchten’s functions. We simulated laboratory and field gas injection experiments in Opalinus clay, a candidate geological formation for the geological disposal of radioactive wastes. The numerical results show good agreement with the experimental data measured in these tests in terms of two-phase flow regimes and hydromechanical response at various monitoring locations. Damage zones, either pre-existing due to excavation or induced by high gas injection pressure, are shown to clearly influence the gas flow rates and directions and would need special consideration in the design and safety assessment of the repository system.

Bubble Formation Due to a Submerged Capillary Tube in Quiescent and Coflowing Streams

1970 ◽  
Vol 92 (4) ◽  
pp. 705-711 ◽  
Author(s):  
S. C. Chuang ◽  
V. W. Goldschmidt
Keyword(s):  
Gas Flow ◽  
Capillary Tube ◽  
Bubble Formation ◽  
Viscous Drag ◽  
Proposed Model ◽  
Mass Coefficient ◽  
Small Tube ◽  
Flow Through ◽  
Added Mass Coefficient ◽  
Good Agreement

The case of bubble formation in both quiescent and moving streams due to the injection of a constant gas flow through a small tube is considered. Relationships predicting the expected size and quantity of bubbles generated are proposed. These are compared with measurements taken with stream velocities up to 9 ft/sec, while generating gas bubbles from 40 to 700 microns in diameter. For the case of generation in a quiescent stream the forces due to the virtual mass, surface tension, viscous drag, buoyancy, and the wake formed by the preceding bubble are accounted for. There still remains some question (only partly answered by a comparison with measurements) as to the proper added mass coefficient and the geometry of the bubble previous to detachment, as well as an adequate estimate of the interaction with a preceding bubble’s wake. The proposed model for generation in a moving stream is in good agreement with actual measurements for co-flowing velocities between 1 and 9 fps and capillary tubes in the order of 10−3 cm in dia.

Gas-Liquid Two-Phase Flow in Hot Embossed Square Microchannels

2007 ◽  
Author(s):  
Namwon Kim ◽  
Estelle T. Evans ◽  
Daniel S. Park ◽  
Dimitris E. Nikitopoulos ◽  
Steven A. Soper ◽  
...  
Keyword(s):  
Weber Number ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Liquid Fraction ◽  
Scaling Law ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Homogeneous Liquid ◽  
Bubble Length

An experimental study was conducted to investigate the characteristics of gas-liquid two-phase flow in 200 μm square microchannels thermoformed in polymer chips. Polymer microfluidic chips were replicated using hot embossing of poly(methyl methacrylate) (PMMA) with micromachined brass mold inserts. The thermoformed microchannels in polymer chips typically had greater surface roughnesses compared to microchannels etched in the silicon substrate. Two more different polymer chips, a direct micromachined PMMA chip and a chip hot embossed with a LIGA nickel mold insert, were fabricated to compare surface characteristics of the sidewalls and bottoms of fabricated microchannels. Deionized water and dry air were injected separately into the chips at superficial velocities of jL = 0.005 – 0.11 m/s for the liquid and jG = 0.003 – 16.67 m/s for the gas. Capillary bubbly, plug, plug-annular, annular, and dry flows were observed in the microchannels. Two-phase flow pattern maps and transitions between flow regimes were determined for fixed values of the homogeneous liquid fraction defined as βL = QL/(QL + QG) where QL and QG are the liquid and gas flow rates, and the liquid Weber number fraction defined as γL = WeL/(WeL + WeG) where WeL and WeG are the liquid and gas Weber number. The surface roughness in submicron range showed minor effect in comparison with the previous work in terms of the gas-liquid two-phase flow patterns and transitions between flow regimes. Dimensionless bubble sizes scaled by the width of observation microchannel were plotted against the homogeneous liquid fraction (βL). A scaling law for the bubble length developed for the previous work with T-junctions was applicable to the present work used the cross junction for generation of segmented flow. With a fixed value of the fitting parameter, scaling law showed a good agreement with the experimental data. Deviation of the scaled bubble length from predicted bubble length line and irregularity of bubble length with a fixed homogeneous liquid fraction increased with higher gas flow rates.

High Power Glow Discharge Using Gas Injection Multiple Porous Electrodes

1987 ◽  
Vol 98 ◽  
Author(s):  
J. E. Harry ◽  
D. R. Evans
Keyword(s):  
Glow Discharge ◽  
Flow Rate ◽  
Gas Flow ◽  
Gas Injection ◽  
Porous Electrodes ◽  
Gas Flow Rate ◽  
Flow Rates ◽  
Glow Discharges ◽  
Power Loading ◽  
Power Inputs

ABSTRACTGlow discharges have been operated at power inputs of 25 kW at 50 mb and discharge currents up to 2 A at gas flow rates of up to 0.04 kg/s in a 100 mm diameter cavity 0.5 m long. This has been made possible by the use of multiple anodes and cathodes combined with gas injection at the porous anodes. Power loading in excess of 700 kW/kg/s have been achieved. The power density of the gas (W/m3) and the current at which the glow to arc transition occurs scaled with both the number of electrode pairs and the gas flow rate through the porous anodes over the range of investigation.

scholarly journals Experimental Study of Bubble Formation from a Micro-Tube in Non-Newtonian Fluid

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 71
Author(s):  
Georgia Kontaxi ◽  
Yorgos G. Stergiou ◽  
Aikaterini A. Mouza
Keyword(s):  
Liquid Phase ◽  
Shear Rate ◽  
Newtonian Fluid ◽  
Gas Flow ◽  
Bubble Formation ◽  
Release Time ◽  
Internal Diameter ◽  
Asymptotic Value ◽  
Shear Thinning Fluids ◽  
A Value

Over the last few years, microbubbles have found application in biomedicine. In this study, the characteristics of bubbles formed when air is introduced from a micro-tube (internal diameter 110 μm) in non-Newtonian shear thinning fluids are studied. The dependence of the release time and the size of the bubbles on the gas phase rate and liquid phase properties is investigated. The geometrical characteristics of the bubbles are also compared with those formed in Newtonian fluids with similar physical properties. It was found that the final diameter of the bubbles increases by increasing the gas flow rate and the liquid phase viscosity. It was observed that the bubbles formed in a non-Newtonian fluid have practically the same characteristics as those formed in a Newtonian fluid, whose viscosity equals the asymptotic viscosity of the non-Newtonian fluid, leading to the assumption that the shear rate around an under-formation bubble is high, and the viscosity tends to its asymptotic value. To verify this notion, bubble formation was simulated using Computational Fluid Dynamics (CFD). The simulation results revealed that around an under-formation bubble, the shear rate attains a value high enough to lead the viscosity of the non-Newtonian fluid to its asymptotic value.

Sign in / Sign up

Export Citation Format

Share Document