Hydrodynamic Predictions of Dense Gas-Solids Flow in CFB Riser

2012 ◽  
Vol 516-517 ◽  
pp. 917-920
Author(s):  
Xue Yao Wang ◽  
Xue Zhi Wu ◽  
Sheng Dian Wang ◽  
Xiang Xu ◽  
Yun Han Xiao
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Circular Cross Section ◽  
Deep Understanding ◽  
Experimental Methods ◽  
Concentration Profiles ◽  
Simulation Research ◽  
Solids Concentration ◽  
High Efficient ◽  
2D Numerical Simulation

The flow character in riser is important for deep understanding the steady and high-efficient running of CFBs. In this paper, the 2D numerical simulation research for bench-scale circular cross-section riser based on EMMS methods is carried out. The solids’ transient moving profiles are captured. By analyzing the axial solids concentration profiles by simulation and experimental methods, the practicability of the EMMS model is verified.

scholarly journals Numerical simulation of minor losses coefficient on the example of elbows

2018 ◽  
Vol 180 ◽  
pp. 02093
Author(s):  
Smyk Emil ◽  
Mrozik Dariusz ◽  
Olszewski Łukasz ◽  
Peszyński Kazimierz
Keyword(s):  
Numerical Simulation ◽  
Numerical Methods ◽  
Numerical Method ◽  
Cross Section ◽  
Analytical Methods ◽  
Circular Cross Section ◽  
Experimental Methods ◽  
Loss Coefficient ◽  
Complicated Problem ◽  
Minor Losses

Determining of minor losses coefficient is very complicated problem. Analytical methods are often very difficult and experimental methods are very expensive and time-consuming. Consequently, the use of numerical methods seems to be a good solution, but there are no publications describing this issue. Therefore, the paper is describing the numerical method of determining the minor loss coefficient ξ on the example of elbows with circular cross-section.

Simulation Research for the Back-Feeder in CFBs

2011 ◽  
Vol 347-353 ◽  
pp. 3758-3761
Author(s):  
Xue Yao Wang ◽  
Jia Chang Wang ◽  
Xiang Xu ◽  
Yun Han Xiao
Keyword(s):  
Numerical Simulation ◽  
Flow Pattern ◽  
Working Conditions ◽  
Flow Rate ◽  
Physical Models ◽  
Stable Operation ◽  
Concentration Profiles ◽  
Simulation Research ◽  
Solids Concentration ◽  
Continuous Running

The flow character of the back-feeder is important for the stable operation and continuous running of CFBs. In this paper, the numerical simulation research for the back-feeder is carried out. The solids concentration profiles in the standpipe and back-feeder are obtained. The influence of the aeration flow rate on the flow pattern and the flow stability is researched. Under the working conditions, the consistence of the flow character between the simulation and the experiment proved the practicability of the mathematic and physical models in this simulation.

scholarly journals The investigation of the cavitation processes in the radial labyrinth pump

2018 ◽  
Vol 8 (1) ◽  
pp. 322-328
Author(s):  
Moloshnyi Oleksandr ◽  
Szulc Przemyslaw
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Volume Fraction ◽  
Mechanical Energy ◽  
Circular Cross Section ◽  
Back Side ◽  
Numerical Investigations ◽  
Numerical Research ◽  
The Moment ◽  
Velocity Pressure

Abstract The paper concerns the analysis of the cavitation processes in the flow passages of the radial labyrinth pump. The object of the analysis contains the active (moving) and the passive (stationary) discs with straight channels trajectory and semi-circular cross-section. The conversion of the mechanical energy into hydraulic based on the exchange of the momentum between the liquid remaining in the moving and the stationary areas of the discs as well as on the centrifugal increase of the moment of momentum. The analysis of the cavitation processes was realized by the experimental research and the numerical simulation. In the article, the comparison of the cavitation characteristics was carried out. The numerical simulation had given similar results to the experimental one, the process of the cavitation was visualized. Furthermore, numerical investigations helped to describe the cavitation development. The results of the numerical research such as the distributions of the velocity, pressure and vapor volume fraction in the passages were presented. At first, cavitation starts on the back side and on the top of the wall between channels of the active disc. Further, the cavitation areas are growing along the axis of the channels. Eventually, they separation was observed and vortices of the vapour-gas mixture in the middle of the channels were formed. This phenomenon is so-called super cavitation vortices.

Rapid motions of free-surface avalanches down curved and twisted channels and their numerical simulation

2005 ◽  
Vol 363 (1832) ◽  
pp. 1551-1571 ◽  
Author(s):  
Shiva P Pudasaini ◽  
Yongqi Wang ◽  
Kolumban Hutter
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Circular Cross Section ◽  
Hyperbolic Partial Differential Equations ◽  
Finite Mass ◽  
Governing Equations ◽  
Cross Sectional ◽  
Variation Diminishing ◽  
Cross Sectional Profile ◽  
Sectional Profile

This paper presents a new model and discussions about the motion of avalanches from initiation to run-out over moderately curved and twisted channels of complicated topography and its numerical simulations. The model is a generalization of a well established and widely used depth-averaged avalanche model of Savage & Hutter and is published with all its details in Pudasaini & Hutter (Pudasaini & Hutter 2003 J. Fluid Mech. 495 , 193–208). The intention was to be able to describe the flow of a finite mass of snow, gravel, debris or mud, down a curved and twisted corrie of nearly arbitrary cross-sectional profile. The governing equations for the distribution of the avalanche thickness and the topography-parallel depth-averaged velocity components are a set of hyperbolic partial differential equations. They are solved for different topographic configurations, from simple to complex, by applying a high-resolution non-oscillatory central differencing scheme with total variation diminishing limiter. Here we apply the model to a channel with circular cross-section and helical talweg that merges into a horizontal channel which may or may not become flat in cross-section. We show that run-out position and geometry depend strongly on the curvature and twist of the talweg and cross-sectional geometry of the channel, and how the topography is shaped close to run-out zones.

scholarly journals Visible Light Shielding Performance of Fabrics with Non-Circular Cross Section Fiber

2012 ◽  
Vol 7 (3) ◽  
pp. 155892501200700
Author(s):  
Xiaosong Liu ◽  
Fumei Wang
Keyword(s):  
Numerical Simulation ◽  
Light Intensity ◽  
Cross Section ◽  
Circular Cross Section ◽  
Transmitted Light ◽  
Characteristic Parameters ◽  
Intensity Ratios ◽  
Shielding Properties ◽  
The Difference ◽  
Better Than

The models of polyethylene terephthalate (PET) non-circular cross-section (NCCS) fibers were established, and the characteristic parameters of non-circular cross-section fiber used in this numerical simulation were extracted. Furthermore, the differences of refracted light intensity ratio Irz and the direction of refracted light βt among circular, trilobal and quadri-lobal cross-section fibers were analyzed theoretically. The results show that the refracted light intensity ratios Irz of these fibers were in the range of 0.94~0.95. Both the trilobal and quadri-lobal cross-section fibers’ βt, which was the angle of refracted light to Y-axis, changed non-monotonically and much more intricately than that of circular cross-section ones. Moreover, according to the theory of geometrical optics, the effects of trilobal and quadri-lobal cross-section shapes on the changes of internal refracted light and transmitted light in fibers were also conducted. The results suggested that the refracted and transmitted light were changed more effectively in the quadri-lobal cross-section fiber. The results of the experiment show that the shielding properties of quadri-lobal cross-section filament fabrics were better than that of the counterparts with circular fibers, but the difference was limited or insignificant.

scholarly journals Numerical Simulation of Tower Rotor Interaction for Downwind Wind Turbine

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Isam Janajreh ◽  
Ilham Talab ◽  
Jill Macpherson
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Cross Sections ◽  
High Speed ◽  
Stokes Equations ◽  
Circular Cross Section ◽  
Time History ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Ale Formulation

Downwind wind turbines have lower upwind rotor misalignment, and thus lower turning moment and self-steered advantage over the upwind configuration. In this paper, numerical simulation to the downwind turbine is conducted to investigate the interaction between the tower and the blade during the intrinsic passage of the rotor in the wake of the tower. The moving rotor has been accounted for via ALE formulation of the incompressible, unsteady, turbulent Navier-Stokes equations. The localizedCP,CL, andCDare computed and compared to undisturbed flow evaluated by Panel method. The time history of theCP, aerodynamic forces (CLandCD), as well as moments were evaluated for three cross-sectional tower; asymmetrical airfoil (NACA0012) having four times the rotor's chord length, and two circular cross-sections having four and two chords lengths of the rotor's chord. 5%, 17%, and 57% reductions of the aerodynamic lift forces during the blade passage in the wake of the symmetrical airfoil tower, small circular cross-section tower and large circular cross-section tower were observed, respectively. The pronounced reduction, however, is confined to a short time/distance of three rotor chords. A net forward impulsive force is also observed on the tower due to the high speed rotor motion.

Numerical Simulation in Steady Flow of Newtonian and Shear Thickening Fluids in Pipes With Circular Cross-Section

2008 ◽  
Author(s):  
F. J. Galindo-Rosales ◽  
F. J. Rubio-Hernández ◽  
Albert Co ◽  
Gary L. Leal ◽  
Ralph H. Colby ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Steady Flow ◽  
Cross Section ◽  
Circular Cross Section ◽  
Shear Thickening ◽  
Shear Thickening Fluids
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