scholarly journals Mixing Characteristics Of Gas-Liquid Flow In A Static Mixer: A Numerical Study

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Ryan Anugrah Putra
Keyword(s):  
Liquid Velocity ◽  
Numerical Study ◽  
Axial Distance ◽  
Sudden Increase ◽  
Static Mixer ◽  
Mixing Condition ◽  
Mixing Characteristics ◽  
Euler Model ◽  
Gas Liquid Flow ◽  
Liquid Flows

Mixing characteristics of gas-liquid co-current upward flow inside a vertical pipe equipped with a helical static mixer element were numerically investigated. The results from computational fluid dynamics (CFD) simulations with Euler-Euler model of three different length to diameter ratio (L/D) of the static mixer elements were compared. All simulated static mixers provide a better mixing condition in the comparison with the one without a static element. The sudden increase of rotational strength indicated by the liquid velocity curl was observed once the gas-liquid flows enter the static-mixer element zone. The smallest L/D static mixer provides the highest liquid velocity curl in the smallest axial distance providing the most effective mixing process among the tested elements. The best mixing characteristics shown by radial gas distribution was achieved with the static mixer with a smallest L/D.

scholarly journals Numerical simulation of the gas-liquid flow inside a horizontal static mixer

2020 ◽  
Vol 5 (2) ◽  
pp. 1-7
Author(s):  
Ryan Anugrah Putra ◽  
Akhlisa Nadiantya Aji Nugroho
Keyword(s):  
Liquid Flow ◽  
Liquid Velocity ◽  
Superficial Velocity ◽  
Static Mixer ◽  
Cfd Simulations ◽  
Mixing Behavior ◽  
Computational Fluid Dynamics Cfd ◽  
Gas Liquid Flow ◽  
Gas Layer ◽  
Superficial Liquid Velocity

The gas-liquid flow inside a horizontal static mixer was numerically investigated by using Euler-Euler Computational Fluid Dynamics (CFD) simulations. The results confirm that the liquid superficial velocity plays a significant role on the mixing behavior of the gas and liquid. The mixing behavior in this present study at a liquid superficial velocity of 0.2 m/s was the worst both axially and radially. Increasing the liquid superficial velocity significantly improve the mixing between gas and liquid. However, the unwanted gas layer still can be found at the superficial liquid velocity less than 0.8 m/s. A good mixing behavior in this study was achieved at a relatively high velocity (i.e. larger than 0.8 m/s).

scholarly journals Velocity bias in intrusive gas-liquid flow measurements

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
B. Hohermuth ◽  
M. Kramer ◽  
S. Felder ◽  
D. Valero
Keyword(s):  
Liquid Flow ◽  
Breaking Waves ◽  
Correction Method ◽  
Force Balance ◽  
Bubble Velocity ◽  
Natural Environments ◽  
Flow Measurements ◽  
Gas Liquid Flow ◽  
Liquid Flows ◽  
Velocity Bias

AbstractGas–liquid flows occur in many natural environments such as breaking waves, river rapids and human-made systems, including nuclear reactors and water treatment or conveyance infrastructure. Such two-phase flows are commonly investigated using phase-detection intrusive probes, yielding velocities that are considered to be directly representative of bubble velocities. Using different state-of-the-art instruments and analysis algorithms, we show that bubble–probe interactions lead to an underestimation of the real bubble velocity due to surface tension. To overcome this velocity bias, a correction method is formulated based on a force balance on the bubble. The proposed methodology allows to assess the bubble–probe interaction bias for various types of gas-liquid flows and to recover the undisturbed real bubble velocity. We show that the velocity bias is strong in laboratory scale investigations and therefore may affect the extrapolation of results to full scale. The correction method increases the accuracy of bubble velocity estimations, thereby enabling a deeper understanding of fundamental gas-liquid flow processes.

Liquid phase residence time distribution for gas–liquid flow in Kenics static mixer

2008 ◽  
Vol 47 (12) ◽  
pp. 2275-2280 ◽  
Author(s):  
Tirupati Reddy Keshav ◽  
P. Somaraju ◽  
K. Kalyan ◽  
A.K. Saroha ◽  
K.D.P. Nigam
Keyword(s):  
Liquid Phase ◽  
Residence Time ◽  
Liquid Flow ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Static Mixer ◽  
Gas Liquid Flow

Bubble Formation From Porous Plates in Liquid Cross-Flow

2018 ◽  
Author(s):  
Thomas Shepard ◽  
Eric Ruud ◽  
Henry Kinane ◽  
Deify Law ◽  
Kohl Ordahl
Keyword(s):  
Size Distribution ◽  
Bubble Size ◽  
Bubble Diameter ◽  
Bubble Formation ◽  
Cross Flow ◽  
Rectangular Channels ◽  
Gas Liquid Flow ◽  
Liquid Flows ◽  
Processing Techniques ◽  
The Impact

Controlling bubble diameter and bubble size distribution is important for a variety of applications and active fields of research. In this study the formation of bubbles from porous plates in a liquid cross-flow is examined experimentally. By injecting air through porous plates of various media grades (0.2 to 100) into liquid flows in rectangular channels of varying aspect ratio (1–10) and gas/liquid flow rates the impact of the various factors is presented. Image processing techniques were used to measure bubble diameters and capture their formation from the porous plates. Mean bubble diameters ranged from 0.06–1.21 mm. The present work expands upon the work of [1] and further identifies the relative importance of wall shear stress, air injector pore size and gas to liquid mass flow ratio on bubble size and size distribution.

scholarly journals Gas-liquid flows through porous media in microgravity: Packed Bed Reactor Experiment-2

2021 ◽  
Author(s):  
Brian Motil ◽  
Mahsa Taghavi ◽  
Vemuri Balakotaiah ◽  
Henry Nahra
Keyword(s):  
Gas Flow ◽  
Liquid Velocity ◽  
Space Station ◽  
Particle Diameter ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Flow Rates ◽  
Test Conditions ◽  
Superficial Gas Velocity ◽  
Liquid Flows

Experimental results on pressure drop and gas hold-up for gas-liquid flow through packed beds obtained from a second flight on the International Space Station are presented and analyzed. It is found that the gas hold-up is a function of the bed history at low liquid and gas flow rates whereas higher gas hold-up and pressure gradients are observed for the test conditions following a liquid only pre-flow compared to the test conditions following a gas only pre-flow period. Over the range of flow rates tested, the capillary force is the dominant contributor to the pressure gradient and is found to be linear with the superficial liquid velocity but is a much weaker function of the superficial gas velocity. The capillary contribution is also a function of the particle size and varies approximately inversely with the particle diameter within the range of the test conditions.

scholarly journals Experimental and Numerical Study of Gas-Liquid Flow for Gold Nanoparticles Synthesis.

2016 ◽  
Vol 4 (7) ◽  
pp. 1148-1154
Author(s):  
Sabrine Mejri ◽  
◽  
Jalila Sghaier ◽  
Ahmed Bellagi. ◽  
◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Liquid Flow ◽  
Numerical Study ◽  
Nanoparticles Synthesis ◽  
Gas Liquid Flow

Simulation of Two Designs of Micro-Mixers With Enhanced Advection Mechanisms

2011 ◽  
Author(s):  
S. A. Kazemi ◽  
M. Passandideh-Fard ◽  
J. Esmaeelpanah
Keyword(s):  
Numerical Study ◽  
Control Volume ◽  
Numerical Technique ◽  
Chaotic Advection ◽  
Mixing Efficiency ◽  
Mixing Length ◽  
Surface Development ◽  
Mixer Design ◽  
Gas Liquid Flow ◽  
Micro Mixer

In this paper, a numerical study of two new designs of passive micro-mixers based on chaotic advection is presented. The advection phenomenon in a T-shaped micro-mixer is enhanced using a segmented gas-liquid flow; and a peripheral/axial mixing mechanism. The simulations are performed for two non-reactive miscible gases: oxygen and methanol. The numerical model employed for this study is based on the solution of the physical governing equations namely the continuity, momentum, species transport and an equation to track the free surface development. The equations are discretized using a control volume numerical technique. The distribution of the species concentration within the domain is calculated based on which a mixing intensity factor is introduced. This factor is then used as a criterion for the mixing length. In the first micro-mixer design with a drop injection mechanism for a typical condition, the mixing length is reduced by nearly 15%. Compared to that of a simple T-shaped micro-mixer with the same flow rates, the two gases interface area is increased in axisymmetric micro-mixer leading to an increase of the mixing efficiency and a reduction of the mixing length. Also, the effects of the baffles height and span on the mixing efficiency and length in axisymmetric micro-mixer are studied. Having baffles in the channel can substantially decrease the mixing length.

Numerical analysis of supersonic co-flow jet with varying lip thickness

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sathish Kumar K ◽  
Naren Shankar R ◽  
Anusindhiya K ◽  
Senthil Kumar B.R
Keyword(s):  
Mach Number ◽  
Total Pressure ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Supersonic Nozzle ◽  
Experimental Result ◽  
Content Type ◽  
Jet Mixing ◽  
Mixing Characteristics ◽  
Jet Axis

Purpose This study aims to present the numerical study on supersonic jet mixing characteristics of the co-flow jet by varying lip thickness (LT). The LT chosen for the study is 2 mm, 7.75 mm and 15 mm. Design/methodology/approach The primary nozzle is designed for delivering Mach 2.0 jet, whereas the secondary nozzle is designed for delivering Mach 1.6 jet. The Nozzle pressure ratio chosen for the study is 3 and 5. To study the mixing characteristics of the co-flow jet, total pressure and Mach number measurements were taken along and normal to the jet axis. To validate the numerical results, the numerical total pressure values were also compared with the experimental result and it is proven to have a good agreement. Findings The results exhibit that, the 2 mm lip is shear dominant. The 7.75 mm and 15 mm lip is wake dominant. The jet interaction along the jet axis was also studied using the contours of total pressure, Mach number, turbulent kinetic energy and density gradient. The radial Mach number contours at the various axial location of the jet was also studied. Practical implications The effect of varying LT in exhaust nozzle plays a vital role in supersonic turbofan aircraft. Originality/value Supersonic co-flowing jet mixing effectiveness by varying the LT between the primary supersonic nozzle and the secondary supersonic nozzle has not been analyzed in the past.

scholarly journals Numerical Study of T-Shaped Micromixers with Vortex-Inducing Obstacles in the Inlet Channels

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1122
Author(s):  
Chih-Yang Wu ◽  
Bing-Hao Lai
Keyword(s):  
Fluid Dynamics ◽  
Reynolds Number ◽  
Particle Tracking ◽  
Concentration Distribution ◽  
Numerical Study ◽  
Fluid Mixing ◽  
Sudden Increase ◽  
New Approach ◽  
Mixing Performance ◽  
Flow Modification

To enhance fluid mixing, a new approach for inlet flow modification by adding vortex-inducing obstacles (VIOs) in the inlet channels of a T-shaped micromixer is proposed and investigated in this work. We use a commercial computational fluid dynamics code to calculate the pressure and the velocity vectors and, to reduce the numerical diffusion in high-Peclet-number flows, we employ the particle-tracking simulation with an approximation diffusion model to calculate the concentration distribution in the micromixers. The effects of geometric parameters, including the distance between the obstacles and the angle of attack of the obstacles, on the mixing performance of micromixers are studied. From the results, we can observe the following trends: (i) the stretched contact surface between different fluids caused by antisymmetric VIOs happens for the cases with the Reynolds number (Re) greater than or equal to 27 and the enhancement of mixing increases with the increase of Reynolds number gradually, and (ii) the onset of the engulfment flow happens at Re≈125 in the T-shaped mixer with symmetric VIOs or at Re≈140 in the standard planar T-shaped mixer and results in a sudden increase of the degree of mixing. The results indicate that the early initiation of transversal convection by either symmetric or antisymmetric VIOs can enhance fluid mixing at a relatively lower Re.

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