scholarly journals STUDY OF CALCITE PRECIPITATION IN WELL CONDITIONS USING THE DDPM-DPM APPROACH

2021 ◽  
Vol 51 (2) ◽  
pp. 101-106
Author(s):  
Suellen Freire Rigatto da Cruz ◽  
Fabio De Assis Ressel Pereira ◽  
Daniel Da Cunha Ribeiro ◽  
André Leibsohn Martins ◽  
Oldrich Joel Romero
Keyword(s):  
Particle Deposition ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Computational Effort ◽  
Scale Formation ◽  
Discrete Phase Model ◽  
Calcite Precipitation ◽  
Discrete Phase ◽  
It Application ◽  
Calcium Carbonate Scale

The extraction of oil results in problems such as the scale formation in the various stages of the production process. The scale reduces all or part of the flow conduits, increasing the pressure drop and reducing oil production. In this work the three dimensional, transient, turbulent, biphasic problem is solved by combining the Dense Discrete Phase Model (DDPM) and Discrete Element Method (DEM), to analyze the influence of certain parameters on the particle deposition, which represents the calcium carbonate scale formation, inside the wall of a horizontal pipeline at well conditions. The obtained results show that particle deposition is higher at lower Reynolds numbers. The results also show that the use of DEM model is more representative, but due to the high computational effort required, it application in complex geometries must be carefully evaluated.

A Numerical Study of Particle Deposition Through Fuel Pebble Bed in HTGR

2018 ◽  
Author(s):  
Qi Sun ◽  
Gang Zhao ◽  
Wei Peng ◽  
Suyuan Yu
Keyword(s):  
Particle Deposition ◽  
Numerical Study ◽  
Three Dimensional ◽  
Intensity Change ◽  
Discrete Phase Model ◽  
Pebble Bed ◽  
Deposition Fraction ◽  
Discrete Phase ◽  
Face Centered ◽  
Fuel Elements

The study on the deposition of graphite dust is significant to the safety of High-Temperature Gas-cooled Reactor (HTGR) due to potential accident such as localized hot-spots and intensity change which is caused by the graphite dust generated by abrasion of fuel elements. Based on the steady flow and three-dimensional face centered structures of fuel pebble bed, the discrete phase model (DPM) were applied to simulate trajectory of graphite dust in conditions of HTGR. To determinate the deposition of particle, the present study introduces a rebound condition with critical velocity by a user defined function. The particle trajectories show most of particle deposition can be summed up as the effect of backflow region, turbulent diffusion and inertial impact. The original trap condition overestimates the deposition fraction especially for large particles compared with involving rebound condition. In addition, the trend of deposition fraction shows as the dimeter of particle increases, deposition fraction decreases first and then increases.

Effect of position of the fiber transport channel on fiber motion in the high-speed rotor

2021 ◽  
pp. 004051752110018
Author(s):  
Rui Hua Yang ◽  
Chuang He ◽  
Bo Pan ◽  
Hongxiu Zhong ◽  
Cundong Xu
Keyword(s):  
High Speed ◽  
Channel Model ◽  
Three Dimensional ◽  
Discrete Phase Model ◽  
Transport Channel ◽  
Rotor Spinning ◽  
Fiber Motion ◽  
Discrete Phase ◽  
Airflow Field ◽  
Fiber Transport

The task of the fiber transport channel (FTC) is to transport the fibers from the carding roller to the rotor. Its geometric position in the spinning machine has a strong influence on the characteristics of the airflow field and the trajectory of the fiber motion in both the rotor and the FTC. In this paper, a three-dimensional pumping rotor spinning channel model was established using ANSYS-ICEM-CFD software with three different positions of the FTC (positions a–c). Further, the simulations of air distribution were performed using Fluent software. In addition, the discrete phase model was used to fit the fiber motion trajectory in the rotor. The simulation results showed that among the three types of FTC, position b is the optimal condition. The gradients of airflow velocity in the channel at position b were greater than those of the other two positions, which is conducive to straightening of the fiber.

Unsteady Modeling of Powdered Activated Carbon Deposition on Collection Electrode of a Lab-Scale Electrostatic Precipitator (ESP)

2012 ◽  
Author(s):  
Yasmin Khakpour ◽  
Herek L. Clack
Keyword(s):  
Activated Carbon ◽  
Particle Deposition ◽  
Electrostatic Precipitator ◽  
Activated Carbons ◽  
Collection Efficiency ◽  
Continuous Phase ◽  
Powdered Activated Carbon ◽  
Computational Domain ◽  
Discrete Phase Model ◽  
Discrete Phase

Particulate sampling in the flue gas at the Electrostatic Precipitator (ESP) outlet during injection of powdered activated carbons (PACs) has provided strong anecdotal evidence indicating that injected PACs can penetrate the ESP in significant concentrations. The low resistivity of PAC is consistent with poor collection efficiency in an ESP and lab-scale testing has revealed significantly different collection behavior of PAC in an ESP as compared to fly ash. The present study illustrates the use of a commercial CFD package — FLUENT — to investigate precipitation of powdered activated carbon (PAC) in the presence and absence of electric field. The computational domain is designed to represent a 2-D wire-plate ESP channel. The governing equations include those covering continuous phase transport, electric potential, air ionization, and particle charging. The particles are tracked using a Lagrangian Discrete Phase Model (DPM). In addition, a custom user-defined function (UDF) uses a deforming boundary condition and a prescribed critical particle velocity to account for particle deposition and dust-cake growth on the electrodes. The effect of Electrohydrodynamics (EHD) induced flow on the ESP collection efficiency under various flow and particle characteristics as well as different ESP configurations are illustrated.

Numerical Calculation on the Influence of Missile Exhaust Plume with Mechanical Properties to the Double-Launch Box

2014 ◽  
Vol 978 ◽  
pp. 101-105
Author(s):  
Jing Li ◽  
Yi Jiang
Keyword(s):  
Three Dimensional ◽  
Engineering Application ◽  
Maximum Pressure ◽  
Common Phenomenon ◽  
Discrete Phase Model ◽  
Exhaust Plume ◽  
Discrete Phase ◽  
Unsteady Numerical Simulation ◽  
Multicomponent Model ◽  
Over Time

The adverse impact of the exhaust plume on the inner wall of the vertical launch box and the former friable lid of the adjacent launch box is a common phenomenon, which causes the deformation or damage of the launch container. By using the three-dimensional unsteady numerical simulation, discrete phase model and multicomponent model, the change of the pressure and temperature with time on many monitoring sites are analyzed. The results show that the pressure and the temperature on the edge of the inner wall significantly rise over time after 0.2s. The pressure on the centerline of the inner wall rises over time after 0.2s but the temperature gradually decreases. The maximum pressure on the former friable lid of the adjacent launch box peaks at 0.54s. The conclusion can be regarded as a theoretical reference for engineering application.

The Growth of Localized Disturbances in Unstable Flows

1982 ◽  
Vol 49 (2) ◽  
pp. 284-290 ◽  
Author(s):  
A. D. D. Craik
Keyword(s):  
Dispersion Relation ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Computational Effort ◽  
Plane Poiseuille Flow ◽  
Linear Dispersion ◽  
Linear Dispersion Relation ◽  
Practical Possibility ◽  
Proposed Model ◽  
Axis Of Symmetry

The development of three-dimensional localized disturbances in unstable flows was recently studied by Craik [1] using a model dispersion relation. The adoption of such an approximate formula for the linear dispersion relation allows a dramatic reduction in computational effort, in comparison with more precise calculations (e.g., Gaster [3], [5]), yet may still yield quite accurate results. Craik [1] gives simple analytical solutions for various limiting cases of his chosen model. Here, this model is further investigated. Numerical results are given which are free of previous scaling assumptions and the accuracy of the proposed model is assessed by comparison with known exact computations for plane Poiseuille flow. Certain improvements are made by including further terms in the model dispersion relation and the influence of these additional terms is determined. A further model is investigated which yields “splitting” of the wave packet into two regions of greatest amplitude, one on either side of the axis of symmetry. Such behavior may be characteristic of many flows at sufficiently large Reynolds numbers. Extension of this work to three-dimensional and slowly varying flows seems a practical possibility.

Simulating Fine Particle Deposition in Coolant Channel of Fast Reactor

2017 ◽  
Author(s):  
Yaoxin Wang ◽  
Tao Zhou ◽  
Bing Li
Keyword(s):  
Fuel Assembly ◽  
Fast Reactor ◽  
Particle Deposition ◽  
Fluid Phase ◽  
Fixed Time ◽  
Mitigation Measures ◽  
Fuel Cladding ◽  
Discrete Phase Model ◽  
Discrete Phase ◽  
Fluent Software

When fast reactor is operation, because of scouring by high pressure liquid coolant in fuel assembly, there are a lot of products in coolant channel. Using FLUENT software simulate deposition of insoluble particle in fast reactor. Using standard k-ε model predict flow field and turbulence intensity of fluid phase. Using discrete phase model track the trajectory of insoluble particle. The following are simulation results. Fuel cladding deposits lots of insoluble particle, but the concentration of insoluble particle is lower at the central of coolant; Entrance section of the insoluble particle concentration is higher than exit section; Dot deposition of insoluble particle at outlet of fuel cladding will lead to pitting phenomenon, pitting will cause deterioration of heat transfer and destroy the integrity of cladding. In view of deposition law of insoluble particle and characteristic of fuel assembly, mitigation measures of cleaning insoluble particle at fixed time and fixed position are being proposed.

Numerical study on the anti-snow performance of deflectors in the bogie region of a high-speed train using the discrete phase model

2018 ◽  
Vol 233 (2) ◽  
pp. 141-159 ◽  
Author(s):  
Guangjun Gao ◽  
Yan Zhang ◽  
Fei Xie ◽  
Jie Zhang ◽  
Kan He ◽  
...  
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Snow Accumulation ◽  
Phase Model ◽  
High Speed Train ◽  
Discrete Phase Model ◽  
Discrete Phase ◽  
Deflector Plate

In this paper, the three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with an RNG double-equation turbulence model and a discrete phase model were used for the investigation of snow accumulation on the bogie of a high-speed train. Two kinds of deflector plates, one installed at the front end and the other at the rear end of the bogie, were proposed to reduce snow accumulation. The accuracy of the CFD methodology was validated against wind tunnel tests. The results showed that high-speed air will impact the plates where snow particles get accumulated. The snow covering on the bogie rarely drifts back into the bogie region with air. The amount of accumulating snow in the optimum models is reduced by 50.58% on average as compared to those in the original models. At the rear end of the bogie, the inclined deflector plate reduced snow accumulation by up to 10.91% compared to the vertical deflector plate.

scholarly journals The Operation of a Three-Bladed Horizontal Axis Wind Turbine under Hailstorm Conditions—A Computational Study Focused on Aerodynamic Performance

Inventions ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 2
Author(s):  
Dimitra Douvi ◽  
Eleni Douvi ◽  
Dionissios P. Margaris
Keyword(s):  
Wind Turbine ◽  
Cross Sections ◽  
Computational Study ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Horizontal Axis ◽  
Discrete Phase Model ◽  
Horizontal Axis Wind Turbine ◽  
Ansys Fluent ◽  
Discrete Phase

The aim of this study is the aerodynamic degradation of a three-bladed Horizontal Axis Wind Turbine (HAWT) under the influence of a hailstorm. The importance and originality of this study are that it explores the aerodynamic performance of an optimum wind turbine blade during a hailstorm, when hailstones and raindrops are present. The commercial Computational Fluid Dynamics (CFD) code ANSYS Fluent 16.0 was utilized for the simulation. The first step was the calculation of the optimum blade geometry characteristics for a three-bladed rotor, i.e., twist and chord length along the blade, by a user-friendly application. Afterwards, the three-dimensional blade and the flow field domain were designed and meshed appropriately. The rotary motion of the blades was accomplished by the application of the Moving Reference Frame Model and the simulation of hailstorm conditions by the Discrete Phase Model. The SST k–ω turbulence model was also added. The produced power of the wind turbine, operating in various environmental conditions, was estimated and discussed. Contours of pressure, hailstone and raindrop concentration and erosion rate, on both sides of the blade, are presented. Moreover, contours of velocity at various cross sections parallel to the rotor are demonstrated, to understand the effect of hailstorms on the wake behavior. The results suggest that the aerodynamic performance of a HAWT degrades due to impact and breakup of the particles on the blade.

Simulation of an Aero-Engine Bearing Compartment Using Two-Way Transition Between Lagrangian Droplets and a Three-Dimensional Eulerian Liquid Film

2019 ◽  
Author(s):  
Jean-Sebastien Dick ◽  
Vivek Kumar ◽  
Pravin Nakod ◽  
Federico Montanari
Keyword(s):  
Liquid Film ◽  
Fluid Model ◽  
Three Dimensional ◽  
Mesh Size ◽  
Liquid Structure ◽  
Discrete Phase Model ◽  
Two Phase ◽  
Aero Engine ◽  
Discrete Phase ◽  
Modeling Strategy

Abstract This paper presents a new hybrid two-phase flow numerical model. It uses the Discrete Phase Model (DPM) and the Volume of Fluid model (VoF) to study the interaction between air, oil droplets and films in a bearing compartment. It allows transition from a trackable Lagrangian particle, such as a droplet, into a continuous liquid structure in a Eulerian frame of reference. The transition can also be performed in the opposite direction, where a continuous liquid structure can be converted back into a trackable particle if specific requirements are met. The method is designated as DPM-VoF-DPM throughout this paper. Test cases capturing the impingement of a droplet in a liquid film are performed to assess its effectiveness. The simulation of a simplified bearing compartment is compared with measurements and results obtained using a standard VoF modeling approach. Mechanisms which are usually modeled such as droplet splashing, film separation, and droplet stripping, can now be physically captured with reduced computing resources by allowing transition from continuous liquid structures to discrete parcels. The employed modeling strategy allows for high resolution of the oil film at the walls and tracking of the droplets while minimizing mesh size and computing needs. Current results suggest that the proposed DPM-VoF-DPM method can be an efficient and accurate tool for locating air and oil in aero-engine transmission systems.

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