Numerical Investigation of the Gas-Solid Flow Characteristics in a Three-Dimensional Spouted Bed with a Draft Tube

2013 ◽  
Vol 36 (12) ◽  
pp. 2035-2043 ◽  
Author(s):  
S.-L. Yang ◽  
K. Luo ◽  
M.-M. Fang ◽  
K. Zhang ◽  
J.-R. Fan
Keyword(s):  
Numerical Investigation ◽  
Draft Tube ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Spouted Bed ◽  
Solid Flow

scholarly journals Numerical Investigation of Liquid–Liquid Mixing in Modified T Mixer with 3D Obstacles

2021 ◽  
pp. 25-32
Author(s):  
Md. Readul Mahmud
Keyword(s):  
Numerical Investigation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Channel Length ◽  
Navier Stokes ◽  
Mixing Efficiency ◽  
Mixing Performance ◽  
Wide Range

The fluids inside passive micromixers are laminar in nature and mixing depends primarily on diffusion. Hence mixing efficiency is generally low, and requires a long channel length and longtime compare to active mixers. Various designs of complex channel structures with/without obstacles and three-dimensional geometries have been investigated in the past to obtain an efficient mixing in passive mixers. This work presents a design of a modified T mixer. To enhance the mixing performance, circular and hexagonal obstacles are introduced inside the modified T mixer. Numerical investigation on mixing and flow characteristics in microchannels is carried out using the computational fluid dynamics (CFD) software ANSYS 15. Mixing in the channels has been analyzed by using Navier–Stokes equations with water-water for a wide range of the Reynolds numbers from 1 to 500. The results show that the modified T mixer with circular obstacles has far better mixing performance than the modified T mixer without obstacles. The reason is that fluids' path length becomes longer due to the presence of obstacles which gives fluids more time to diffuse. For all cases, the modified T mixer with circular obstacle yields the best mixing efficiency (more than 60%) at all examined Reynolds numbers. It is also clear that efficiency increase with axial length. Efficiency can be simply improved by adding extra mixing units to provide adequate mixing. The value of the pressure drop is the lowest for the modified T mixer because there is no obstacle inside the channel. Modified T mixer and modified T mixer with circular obstacle have the lowest and highest mixing cost, respectively. Therefore, the current design of modified T with circular obstacles can act as an effective and simple passive mixing device for various micromixing applications.

Experimental and numerical investigation of interactions between above and below ground drainage systems

2013 ◽  
Vol 67 (3) ◽  
pp. 535-542 ◽  
Author(s):  
Slobodan Djordjević ◽  
Adrian J. Saul ◽  
Gavin R. Tabor ◽  
John Blanksby ◽  
Istvan Galambos ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Urban Areas ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Sewer Pipes ◽  
Drainage Systems ◽  
Flow Features ◽  
Below Ground ◽  
Set Up ◽  
Flood Flow

This paper presents the results of the experimental and numerical investigation of interactions between surface flood flow in urban areas and the flow in below ground drainage systems (sewer pipes and manholes). An experimental rig has been set up at the Water Engineering Laboratory at the University of Sheffield. It consists of a full scale gully structure with inlet grating, which connects the 8 m2 surface area with the pipe underneath that can function as an outfall and is also further connected to a tank so that it can come under surcharging conditions and cause outflow from the gully. A three-dimensional CFD (Computational Fluid Dynamics) model has been set up to investigate the hydraulic performance of this type of gully inlet during the interactions between surface flood flow and surcharged pipe flow. Preliminary results show that the numerical model can replicate various complex 3D flow features observed in laboratory conditions. This agreement is overall better in the case of water entering the gully than for the outflow conditions. The influence of the surface transverse slope on flow characteristics has been demonstrated. It is shown that re-circulation zones can form downstream from the gully. The number and size of these zones is influenced by the transverse terrain slope.

Three-dimensional simulation of the effect of draft tube on minimum fluidization velocity in a spouted bed

2012 ◽  
Vol 46 (5) ◽  
pp. 458-463 ◽  
Author(s):  
Sara Moradi ◽  
Zeinab Asadi ◽  
Sadegh Moradi ◽  
Mahmoud Salimi ◽  
Seyed S. Homami ◽  
...  
Keyword(s):  
Draft Tube ◽  
Three Dimensional ◽  
Spouted Bed ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Dimensional Simulation

Simulation of Gas-Solid Flow Characteristics in Three-Dimensional Rotational Spouted-Fluidized Bed

2014 ◽  
Vol 496-500 ◽  
pp. 913-917
Author(s):  
Xin Feng Long ◽  
Yi Liu ◽  
Bo Lou
Keyword(s):  
Fluidized Bed ◽  
Gas Flow ◽  
Solid Phase ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cylinder Wall ◽  
Flow State ◽  
Solid Flow ◽  
Tangential Wind

In order to study the gas-solid flow characteristics in a rotational spouted-fluidized bed dryer, the eulerian multi-phase model was applied in three-dimensional numerical simulation of a rotational spouted-fluidized bed to analyze the effect of different velocity ratios between bottom and tangential wind on gas and particle velocity distribution characteristics, and the change rule of gas-solid flow state with the time at the velocity ratio of 30 m·s-1/30 m·s-1 was derived. The results show that the increase of tangential wind velocity is propitious to enhance the gas flow rate in the region near the wall and make the gas-solid phase mix sufficiently as well as augment of the contact area of gas and particle phase, and decrease of the gas flow dead zones and the adhesion of viscous materials to cylinder wall. However, the negative pressure formed by the entrainment effect of tangential wind goes against the development of gas flow along the axial direction reducing the penetration effect of axial wind to the granular layer.

scholarly journals Flow Characteristics of Draft Tube Spouted Bed and Its Application.

1997 ◽  
Vol 34 (5) ◽  
pp. 343-360 ◽  
Author(s):  
Yasuo HATATE ◽  
Kazuya IJICHI ◽  
Yoshimitsu UEMURA
Keyword(s):  
Draft Tube ◽  
Flow Characteristics ◽  
Spouted Bed
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