Flow conditions in the grooves of a Low-Consistency refiner

2012 ◽  
Vol 27 (2) ◽  
pp. 173-183 ◽  
Author(s):  
Lisa Prahl Wittberg ◽  
Magnus Björkman ◽  
Gohar Khokhar ◽  
Ulla-Britt Mohlin ◽  
Anders Dahlkild
Keyword(s):  
Fluid Dynamics ◽  
Flow Pattern ◽  
High Speed ◽  
Cfd Simulation ◽  
Flow Conditions ◽  
Shear Forces ◽  
High Speed Imaging ◽  
Newtonian Flows ◽  
Computational Fluid Dynamics Cfd ◽  
Vortical Motion

Abstract The flow pattern in the grooves plays a major role for the homogeneity of refining as well as for the transfer and loading of fiber flocs in refining position on the bar edges. However, it is an area where very little information is available. In the present study, flow conditions in the grooves in a Low-Consistency (LC) - disc refiner were studied both experimentally and numerically. The experimental study involved high-speed imaging through a 3 cm peephole into a commercial refiner. The Computational Fluid Dynamics (CFD) simulation focused on the flow condition in a radial groove, considering both Newtonian and non-Newtonian flows. Flow conditions for stator and rotor grooves were modeled along the groove at different angular speeds and pressure differences over the refiner. Both the experimental and the modeling results show a dual flow pattern in the grooves; a rotational/spiral movement at the top of the groove and a flow in the direction of the groove at the bottom, which to the authors knowledge has not been reported in literature. The strong vortical motion at the top of the grooves observed both for the rotor and the stator are believed to be important for placing the fibers onto the bar edges and to induce shear forces in such a way that the fibers get treated. Moreover, a large sensitivity to suspension properties in terms of the development of flow pattern was detected.

Application of Computational Fluid Dynamics Simulation to Squeeze Film Damper Analysis

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Gil Jun Lee ◽  
Jay Kim ◽  
Tod Steen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Cfd Simulation ◽  
Design Guidelines ◽  
Dynamics Simulation ◽  
Squeeze Film ◽  
Computational Time ◽  
Small Clearance ◽  
Computational Fluid Dynamics Cfd

Squeeze film dampers (SFDs) are used in high-speed turbomachinery to provide external damping to the system. Computational fluid dynamics (CFD) simulation is a highly effective tool to predict the performance of SFDs and obtain design guidance. It is shown that a moving reference frame (MRF) can be adopted for CFD simulation, which saves computational time significantly. MRF-based CFD analysis is validated, then utilized to design oil plenums of SFDs. Effects of the piston ring clearances, the oil groove, and oil supply ports are studied based on CFD and theoretical solutions. It is shown that oil plenum geometries can significantly affect the performance of the SFD especially when the SFD has a small clearance. The equivalent clearance is proposed as a new concept that enables quick estimation of the effect of oil plenum geometries on the SFD performance. Some design practices that have been adopted in industry are revisited to check their validity. Based on simulation results, a set of general design guidelines is proposed.

Impedance Characteristics of Hydraulic Orifices

1995 ◽  
Vol 209 (4) ◽  
pp. 241-253 ◽  
Author(s):  
K K Lau ◽  
K A Edge ◽  
D N Johnston
Keyword(s):  
Fluid Dynamics ◽  
Cfd Simulation ◽  
Generic Model ◽  
Simulation Studies ◽  
Hydraulic Systems ◽  
Flow Conditions ◽  
Mean Flow ◽  
Impedance Characteristics ◽  
Pressure Ripple ◽  
Computational Fluid Dynamics Cfd

The impedance characteristics of cylindrical and sharp-edged hydraulic orifices under non-zero mean flow conditions have been investigated through experimental measurement and computational fluid dynamics (CFD) simulation studies. Based upon these investigations a generic model of the impedance characteristics of orifices has been developed. This model can be adopted in computer simulations of pressure ripple in hydraulic systems. The results of this investigation also provide the basis for modelling more complex hydraulic components.

Computational fluid dynamics (CFD) simulation of hot air flow pattern in cabinet drying of osmo-pretreated green bell pepper

2017 ◽  
Vol 12 (1) ◽  
pp. 36
Author(s):  
Michael Mayokun Odewole ◽  
Musliu Olushola Sunmonu ◽  
Samuel Kehinde Oyeniyi ◽  
Oluwatosin Adedamola Adesoye
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Pattern ◽  
Cfd Simulation ◽  
Air Flow ◽  
Bell Pepper ◽  
Hot Air ◽  
Computational Fluid Dynamics Cfd

scholarly journals Computational Fluid Dynamics (CFD) Simulation on Mixing in T-Shaped Micromixer

2020 ◽  
Vol 932 ◽  
pp. 012006
Author(s):  
S N A Ahmad Termizi ◽  
C Y Khor ◽  
M A M Nawi ◽  
Nurlela Ahmad ◽  
Muhammad Ikman Ishak ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Computational Fluid Dynamics Cfd

A Study on the Performance of Stratified Air Conditioning Design in Assembly Halls – A Case Study at the Dazhi Cultural Center in Taiwan

2013 ◽  
Vol 368-370 ◽  
pp. 599-602 ◽  
Author(s):  
Ian Hung ◽  
Hsien Te Lin ◽  
Yu Chung Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Indoor Air ◽  
Air Conditioning ◽  
Cfd Simulation ◽  
Indoor Temperature ◽  
Cultural Center ◽  
Computational Fluid Dynamics Cfd

This study focuses on the performance of air conditioning design at the Dazhi Cultural Center and uses a computational fluid dynamics (CFD) simulation to discuss the differences in wind velocity and ambient indoor temperature between all-zone air conditioning design and stratified air conditioning design. The results have strong implications for air conditioning design and can improve the indoor air quality of assembly halls.

Characterisation of Cell Adhesion to Substrate Materials and the Resistance to Enzymatic and Mechanical Cell-Removal

2008 ◽  
Vol 1097 ◽  
Author(s):  
Helen Jane Griffiths ◽  
John G Harvey ◽  
James Dean ◽  
James A Curran ◽  
Athina E Markaki ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cell Adhesion ◽  
Liquid Flow ◽  
Adhesive Strength ◽  
Cell Detachment ◽  
Shear Forces ◽  
Cfd Modelling ◽  
Computational Fluid Dynamics Cfd

AbstractCell-implant adhesive strength is important for prostheses. In this paper, an investigation is described into the adhesion of bovine chondrocytes to Ti6Al4V-based substrates with different surface roughnesses and compositions. Cells were cultured for 2 or 5 days, to promote adhesion. The ease of cell removal was characterised, using both biochemical (trypsin) and mechanical (accelerated buoyancy and liquid flow) methods. Computational fluid dynamics (CFD) modelling has been used to estimate the shear forces applied to the cells by the liquid flow. A comparison is presented between the ease of cell detachment indicated using these methods, for the three surfaces investigated.

Transient Computational Fluid Dynamics/Discrete Element Method Simulation of Gas–Solid Flow in a Spouted Bed and Its Validation by High-Speed Imaging Experiment

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Ling Zhou ◽  
Lingjie Zhang ◽  
Weidong Shi ◽  
Ramesh Agarwal ◽  
Wei Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Discrete Element Method ◽  
Fluidized Bed ◽  
High Speed ◽  
Discrete Element ◽  
Bubble Shape ◽  
High Speed Imaging ◽  
Bed Height ◽  
Simulation Results

A coupled computational fluid dynamics (CFD)/discrete element method (DEM) is used to simulate the gas–solid two-phase flow in a laboratory-scale spouted fluidized bed. Transient experimental results in the spouted fluidized bed are obtained in a special test rig using the high-speed imaging technique. The computational domain of the quasi-three-dimensional (3D) spouted fluidized bed is simulated using the commercial CFD flow solver ANSYS-fluent. Hydrodynamic flow field is computed by solving the incompressible continuity and Navier–Stokes equations, while the motion of the solid particles is modeled by the Newtonian equations of motion. Thus, an Eulerian–Lagrangian approach is used to couple the hydrodynamics with the particle dynamics. The bed height, bubble shape, and static pressure are compared between the simulation and the experiment. At the initial stage of fluidization, the simulation results are in a very good agreement with the experimental results; the bed height and the bubble shape are almost identical. However, the bubble diameter and the height of the bed are slightly smaller than in the experimental measurements near the stage of bubble breakup. The simulation results with their experimental validation demonstrate that the CFD/DEM coupled method can be successfully used to simulate the transient gas–solid flow behavior in a fluidized bed which is not possible to simulate accurately using the granular approach of purely Euler simulation. This work should help in gaining deeper insight into the spouted fluidized bed behavior to determine best practices for further modeling and design of the industrial scale fluidized beds.

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