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1
Chattopadhyay, Kinnor, Mihaiela Isac und Roderick I. L. Guthrie. „Considerations in Using the Discrete Phase Model (DPM)“. steel research international 82, Nr. 11 (21.06.2011): 1287–89. http://dx.doi.org/10.1002/srin.201000214.
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2
Latif, Shahid, Zhou Hong und Muhammad Ismail. „Aerodynamic Characteristics of NACA 23015 Landing Configuration with 20o Flap in Simulated Rain“. Applied Mechanics and Materials 555 (Juni 2014): 108–12. http://dx.doi.org/10.4028/www.scientific.net/amm.555.108.
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In our numerical simulation the heavy rain effects have been studied on the aerodynamic performance of 2D cambered NACA 23015 airfoil landing configuration with 20o. We have used preprocessing software gridgen for creation of the landing configuration of the airfoil and then creating mesh around it. Fluent is used to solve the conservation equations. We have used discrete phase modeling (DPM) in Fluent to simulate the rain phenomenon in continuous phase flow by using two phase flow approach. In our study the coupling between the discrete and the continuous phase has been activated. In discrete phase model (DPM), we used the wall film model for the interaction of the continuous and discrete phase. The airfoil landing configuration exhibited significant decrease in lift and increase in drag for a given lift conditions in simulated rain. Post processing software like MATLAB, Tec plot and Origin are used to see the effects of the heavy rain and then results obtained are compared with the experimental results. Our numerical results in most of cases show similar trends with the experiments.
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Freire Rigatto da Cruz, Suellen, Fabio De Assis Ressel Pereira, Daniel Da Cunha Ribeiro, André Leibsohn Martins und Oldrich Joel Romero. „STUDY OF CALCITE PRECIPITATION IN WELL CONDITIONS USING THE DDPM-DPM APPROACH“. Latin American Applied Research - An international journal 51, Nr. 2 (20.03.2021): 101–6. http://dx.doi.org/10.52292/j.laar.2021.215.
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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.
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Ohsaki, Shuji, Ryosuke Mitani, Saki Fujiwara, Hideya Nakamura und Satoru Watano. „Numerical Simulation of Particle Motions in Cascade Impactor and Human Respiratory System“. MATEC Web of Conferences 333 (2021): 02013. http://dx.doi.org/10.1051/matecconf/202133302013.
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Dry powder inhalations (DPIs) have gathered attention as a treatment for respiratory diseases due to the large effective absorption area in a human lung. A cascade impactor is generally used to investigate the inhalation performance of DPIs. For the improvement of the efficiency of DPIs, understanding the particle motion and deposition behavior in the human lung and the cascade impactor is required. In the present study, computer simulations were conducted to calculate the particle motion and deposition behavior in the human lung and the cascade impactor. As simulation methods, a coupling model of a computational fluid dynamics and a discrete phase method (CFD−DPM) and a coupling model of a CFD and a discrete element method (CFD−DEM) were used. The CFD−DEM simulation could reproduce the experimental particle deposition behavior in the cascade impactor, although it was difficult by the CFD−DPM simulation. Furthermore, the calculation results using the CFD−DEM simulation quantitatively demonstrated the higher particle reachability into the simple lung model when smaller particles were used. It was found that the CFD−DEM simulation is a powerful tool to calculate the particle motion and deposition behavior in the cascade impactor and human lung.
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Ohsaki, Shuji, Ryosuke Mitani, Saki Fujiwara, Hideya Nakamura und Satoru Watano. „Numerical Simulation of Particle Motions in Cascade Impactor and Human Respiratory System“. MATEC Web of Conferences 333 (2021): 02013. http://dx.doi.org/10.1051/matecconf/202133302013.
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Dry powder inhalations (DPIs) have gathered attention as a treatment for respiratory diseases due to the large effective absorption area in a human lung. A cascade impactor is generally used to investigate the inhalation performance of DPIs. For the improvement of the efficiency of DPIs, understanding the particle motion and deposition behavior in the human lung and the cascade impactor is required. In the present study, computer simulations were conducted to calculate the particle motion and deposition behavior in the human lung and the cascade impactor. As simulation methods, a coupling model of a computational fluid dynamics and a discrete phase method (CFD−DPM) and a coupling model of a CFD and a discrete element method (CFD−DEM) were used. The CFD−DEM simulation could reproduce the experimental particle deposition behavior in the cascade impactor, although it was difficult by the CFD−DPM simulation. Furthermore, the calculation results using the CFD−DEM simulation quantitatively demonstrated the higher particle reachability into the simple lung model when smaller particles were used. It was found that the CFD−DEM simulation is a powerful tool to calculate the particle motion and deposition behavior in the cascade impactor and human lung.
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Xu, Rang Shu, Juan Juan Wang, Wei Xu und Li Bo Liu. „Numerical DPM Model for Two-Phase Flow in Aero-Engine Bearing Chamber“. Advanced Materials Research 201-203 (Februar 2011): 2267–70. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.2267.
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The main bearing chamber is a major part of the lubrication system in aero-engine, it is important to know the influence of operation parameters on air/oil two-phase flow, so as to optimize the design of aero-engine lubrication system. The air/oil two-phase flow in a simplified bearing chamber model in an aero-engine is simulated by means of discrete phase model (DPM) and wall-film model with CFD approach. The simulation results coincide with the existing experimental data. The oil film thickness and concentration of droplets in bearing chamber are presented at different rotational speeds and different lubricating oil flow rates.
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Chang, Ping, Guang Xu, Fubao Zhou, Benjamin Mullins und S. Abishek. „Comparison of underground mine DPM simulation using discrete phase and continuous phase models“. Process Safety and Environmental Protection 127 (Juli 2019): 45–55. http://dx.doi.org/10.1016/j.psep.2019.04.027.
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8
Li, Liang Chao. „CFD-DPM Modeling of Gas-Liquid Flow in a Stirred Vessel“. Advanced Materials Research 550-553 (Juli 2012): 979–83. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.979.
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Gas-liquid flow in a stirred vessel was simulated numerically with computational fluid dynamics(CFD). Gas was treated as discrete phase and described by discrete phase model (DPM), while the liquid was considered as a continuum and solved under Euler reference frame. The liquid velocity, gas holdup and gas residence time distribution in the stirred vessel were predicted. The simulation results show that gas dispersion in the stirred vessel is very non-uniformity and high gas holdup is found in the centre of the stirred vessel and vortexes while relatively low in bottom region and region between two impellers. Liquid velocity has great influence on bubble residence time and size distributions.
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Cârlescu, Petru, Ioan Tenu, Marius Baetu und Radu Rosca. „CFD Study on must of Grapes Separation in a Hydrocyclone“. Advanced Materials Research 837 (November 2013): 645–50. http://dx.doi.org/10.4028/www.scientific.net/amr.837.645.
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Abstract. Hydrocyclones are increasingly used in the food industry for various separation and purification. In this paper, an optimization was made to design a hydrocyclone model using CFD (Computational Fluid Dynamics). CFD simulation is performed with FLUENT software by coupling the Reynolds Stress Model (RSM) for must of grapes flow with Discrete Phase Model (DPM) for solid particles trajectory. Coupling of discrete phase (particles) and continuous phase (must of grapes) in the mathematical model is set so that the continuous phase to influence discrete phase. Tracking particles traiectory in this hydrocyclone allows advanced degree is separation so obtained to the maximum particle size approaching the size of a yeast cell 10 μm, without separating them. Hydrocyclone dimensional designed simulation was performed and analyzed on an experimental pilot plant for three different must flow rates supply. Introduced particle flow rates simulation and experiment does not exceed 10% of the must flow rates. The degree of separation obtained is in agreement with experimental data.
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M.Mukhtar, M. A. Fatah, Aizat Abas, M. S. Haslinda, F. Che Ani, M. Z. Abdullah, A. Jalar und R. Ismail. „Discrete Phase Model (DPM) study of nano-reinforced Lead Free Solder Sn-3.0Ag-0.5Cu (SAC305)“. IOP Conference Series: Materials Science and Engineering 370 (Mai 2018): 012067. http://dx.doi.org/10.1088/1757-899x/370/1/012067.
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Yang, Daolong, Ge Li, Yanxiang Wang, Qingkai Wang, Jianping Li, Qianqian Huang, Youtao Xia und Qian Li. „Prediction of Horizontal Pneumatic Conveying of Large Coal Particles Using Discrete Phase Model“. Advances in Materials Science and Engineering 2020 (12.05.2020): 1–15. http://dx.doi.org/10.1155/2020/1967052.
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The pneumatic conveying focusing on gas-solid two-phase flow plays an important role in a conveying system. Previous work has been conducted in the fields of small particles, where the size was less than 5 mm; however, there are few studies regarding large sizes (>5 mm). In order to predict the horizontal pneumatic conveying of large coal particles, the coupling methods based on the Euler–Lagrange approach and discrete phase model (DPM) have been used for the simulated research. Compared with the experimental results under the same working condition, the particle trajectory obtained by simulation is similar to the particle distribution at the same position in the experiment, and it turns out that the simulation method is feasible for the horizontal pneumatic conveying of large particles. Multifactor simulations are also carried out to analyse the effects of particle size, flow field velocity, solid-gas rate, and pipe diameter on the wall abrasion during horizontal pneumatic conveying, which provides simulation reference and design guide for pneumatic conveying of large particles.
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Ji, Shi Ming, Feng Qing Xiao und Da Peng Tan. „A New Ultraprecision Machining Method with Softness Abrasive Flow Based on Discrete Phase Model“. Advanced Materials Research 97-101 (März 2010): 3055–59. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.3055.
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Considering the demand of precision in mould structural surface polishing method, a new method based on soft abrasive flow machining(SAFM) was proposed, which was supposed to achieve polydirectional and multi-angle cutting acting on the surface of the workpiece by utilizing the irregular motion of both wear particles and the media in turbulence flow. Thus as the monodirectional marks on the machined surfaces was eliminated, the disadvantage in machining precision in conventional abrasive flow machining(AFM) method would be overcome. According to the particle distribution characteristics of SAFM, a two-phase dynamic model of abrasive flow oriented to SAFM combined with Discrete Phase Model(DPM) was built to analog simulation with the software Fluent. Sequently the mechanism of ultraprecision machining towards mould structural surface was analyzed briefly. Simulation results show that the abrasive efficiency along the flow passage can be influenced by the development of turbulence and the distribution of dispersed phase. Thus there a specific region can be obtained in the passage in which the abrasive efficiency is relatively stable.
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Yu, Zheqin, Jianping Tan und Shuai Wang. „Enhanced discrete phase model for multiphase flow simulation of blood flow with high shear stress“. Science Progress 104, Nr. 1 (Januar 2021): 003685042110080. http://dx.doi.org/10.1177/00368504211008064.
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Shear stress is often present in the blood flow within blood-contacting devices, which is the leading cause of hemolysis. However, the simulation method for blood flow with shear stress is still not perfect, especially the multiphase flow model and experimental verification. In this regard, this study proposes an enhanced discrete phase model for multiphase flow simulation of blood flow with shear stress. This simulation is based on the discrete phase model (DPM). According to the multiphase flow characteristics of blood, a virtual mass force model and a pressure gradient influence model are added to the calculation of cell particle motion. In the experimental verification, nozzle models were designed to simulate the flow with shear stress, varying the degree of shear stress through different nozzle sizes. The microscopic flow was measured by the Particle Image Velocimetry (PIV) experimental method. The comparison of the turbulence models and the verification of the simulation accuracy were carried out based on the experimental results. The result demonstrates that the simulation effect of the SST k- ω model is better than other standard turbulence models. Accuracy analysis proves that the simulation results are accurate and can capture the movement of cell-level particles in the flow with shear stress. The results of the research are conducive to obtaining accurate and comprehensive analysis results in the equipment development phase.
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Cetin, Yunus Emre, Mete Avci und Orhan Aydin. „Effect of Air Exchange Rate on Particle Decay in a Cleanroom: A Numerical Study“. E3S Web of Conferences 111 (2019): 01037. http://dx.doi.org/10.1051/e3sconf/201911101037.
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In this study, particle decay in a cleanroom is investigated numerically. A commercial CFD package, FLUENT, is used in the analysis. The governing equations are solved by using the k-å turbulence model. For particle dispersion, the discrete phase model (DPM) is applied. Four different air change rates (3-10-25-43 ACH) with three particle diameters (0,5-5-10 ìm) are considered. It is shown that 10 ACH satisfies the needs in terms of recovery time.
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Li, Xianglong, Baokuan Li, Zhongqiu Liu, Ran Niu, Yanqiang Liu, Changliang Zhao, Caide Huang, Huanshan Qiao und Tianxiang Yuan. „Large Eddy Simulation of Multi-Phase Flow and Slag Entrapment in a Continuous Casting Mold“. Metals 9, Nr. 1 (21.12.2018): 7. http://dx.doi.org/10.3390/met9010007.
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A transient, three-dimensional mathematical model has been developed to study the slag entrapment in a continuous casting mold. The unsteady turbulent flow is computed using the large eddy simulation (LES). The sub-grid scale structure is modeled by the Smagorinsky–Lilly model. The movements of discrete bubbles, as well as three continuous phases (air–slag–steel), are described by solving the coupled discrete particle model and volume of fraction (DPM+VOF) approach. The bubble transport inside different phases (steel and slag) and the escape near the air–slag interface are well studied. Good agreement is obtained by comparing with the plant observation of the slag eyes on the top surface of the mold. Three main mechanisms of slag entrapment are identified; vortex formation, shear-layer instability, and meniscus fluctuation. Four stages are observed for a slag entrapment: deformation, necking, breaking, and dragging in the mold. The model is helpful for understanding the formation of slag entrapment during continuous casting.
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Shi, Wei Dong, Liang Zhang, Hai Yan He, Jiang Hai Liu und Liang Chen. „Numerical Simulation of Two-Phase Flow inside and outside a Swirl Nozzle for Dispersing Superfine Powder“. Advanced Materials Research 505 (April 2012): 170–74. http://dx.doi.org/10.4028/www.scientific.net/amr.505.170.
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In this paper, a swirl nozzle is established to disperse superfine powder aerodynamically. And Reynolds stress model (RSM) is adopted to simulate the strongly swirling, compressible and transonic gas flow in the nozzle and its rear. Combined with discrete phase model (DPM), the concentration distribution of particle group in size of 2.5μm is studied. The simulated results show that, the distribution of swirl strength is determined basically by the nozzle structure, while the total pressure has little effect on it; compared with an irrotational nozzle, the swirl nozzle could achieve a better dispersing effect for superfine powder.
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Zhu, Hongjun, Hongnan Zhao, Qian Pan und Xue Li. „Coupling Analysis of Fluid-Structure Interaction and Flow Erosion of Gas-Solid Flow in Elbow Pipe“. Advances in Mechanical Engineering 6 (01.01.2014): 815945. http://dx.doi.org/10.1155/2014/815945.
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A numerical simulation has been conducted to investigate flow erosion and pipe deformation of elbow in gas-solid two-phase flow. The motion of the continuous fluid phase is captured based on calculating three-dimensional Reynolds-averaged-Navier-Stokes (RANS) equations, while the kinematics and trajectory of the discrete particles are evaluated by discrete phase model (DPM), and a fluid-structure interaction (FSI) computational model is adopted to calculate the pipe deformation. The effects of inlet velocity, pipe diameter, and the ratio of curvature and diameter on flow feature, erosion rate, and deformation of elbow are analyzed based on a series of numerical simulations. The numerical results show that flow field, erosion rate, and deformation of elbow are all sensitive to the structural changes and inlet condition changes. Higher inlet rate, smaller curvature diameter ratio, or smaller pipe diameter leads to greater deformation, while slower inlet rate, larger curvature diameter ratio, and larger pipe diameter can weaken flow erosion.
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Montaseri, H., K. Tavakoli, S. Evangelista und P. Omidvar. „Sediment transport and bed evolution in a 180∘ curved channel with lateral intake: Numerical simulations using Eulerian and Discrete Phase models“. International Journal of Modern Physics C 31, Nr. 08 (August 2020): 2050113. http://dx.doi.org/10.1142/s0129183120501132.
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Lateral intakes are hydraulic structures used for domestic, agricultural and industrial water conveyance, characterized by a very complex three-dimensional morphodynamic behavior: since streamlines near the lateral intake are deflected, some vortices form, pressure gradient, shear and centrifugal forces at the intake generate flow separation and a secondary movement, responsible for local scour and sediment deposition. On the other side, the modeling of flows, besides the sediment transport, in curved channels implies some more complications in comparison with straight channels. In this research, this complex process has been investigated experimentally and numerically, with the mechanism of sediment transport, bed topography evolution, flow pattern and their interactions. Experiments were performed in the Laboratory of Tarbiat Modares University, Iran, where a U-shaped channel with a lateral intake was installed and dry sediment was injected at constant rate into a steady flow. Due to the spiral flow, the bed topography changes significantly and the bed forms in turn affect the sediment entering the intake. Different from the previous works on this topic which were mainly based on laboratory experiments, here, Computational Fluid Dynamics (CFD) numerical simulations with FLUENT software were also performed, specifically with the two-phase Eulerian Model (EM) and Discrete Phase Model (DPM), at the aim of evaluating their performance in reproducing the observed physical processes. This software is used for a large variety of CFD problems, but not much for simulating sediment transport phenomena and bed topography evolution. The comparison of the results obtained through the two models against the laboratory experimental data proved a good performance of both the models in reproducing the main features of the flow, for example, the longitudinal and vertical streamlines and the mechanism of particles movement. However, the EM reveals a better performance than DPM in the prediction of the secondary flows and, consequently, of the bed topography evolution, whereas the DPM well depicts the particles pattern, predicts the location of trapped particles and determines the percentage of sediment entering the intake. The numerical models so calibrated and validated were applied to other cases with different positions of the intake in the bend. The results show that mechanism of sediment entrance into the intake varies in different position. If the intake is installed in the second half of the bend, the sediment accumulates along the inner bank of the bend and enters the intake from downstream edge of intake; on the other side, if it is placed in the first half of the bend, the sediment accumulates along both the inner and the outer bends and, therefore, more sediment enters the intake. Also the results of the simulations performed with the DPM model for different positions of the lateral intake show that for all discharge ratios, the position of 120∘ is the one which guarantees the minimum ratio of sediment diverted to the intake (Gr).
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Zhang, Wei, Fenglei Niu, Shiji Wang, Haonan Wang und Zhangpeng Guo. „Study on Performance of Mesoscopic Impactor Filters for Aerosol Removal“. Science and Technology of Nuclear Installations 2019 (26.11.2019): 1–10. http://dx.doi.org/10.1155/2019/7036957.
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The mesoscopic impactor filter is designed to filtrate aerosols in the containment, which has not only high collection efficiency but also small flow resistance. In this paper, the influence of structural parameters and working parameters of the inertial impactor on collection performance is studied by the computational fluid dynamic (CFD) method. Under the small Reynolds number, the laminar model is used to simulate the continuous phase, and the discrete phase model (DPM) is used to track the trajectory of the particle. Based on the response surface methodology (RSM), the prediction model of collection efficiency and pressure drop is obtained, which will provide a reference for the design and manufacture of the filter in the future.
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Zhang, Zhen Wei, Yong Sheng Zhou, Tao Zhou und Xiang Lei Ji. „Research on Simulating Structural Parameters' Impact on the Flow of Two Phases in Separator“. Advanced Materials Research 740 (August 2013): 387–90. http://dx.doi.org/10.4028/www.scientific.net/amr.740.387.
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Adopting the RSM (Reynolds stress model) to conduct numerical simulation on gas phase flow field in bypass cyclone separators with two kinds of inlet structure, meanwhile, interphase coupling discrete model DPM is used to simulate the trace of particles in bypass cyclone separator. At last, the results demonstrate that the separating efficiency of separator B with a large length-width ratio inlet increased 1%~2% and the pressure drop is smaller when compared with separator A. A low average entering position and a short distance to the wall are helpful to improve the separating efficiency.
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Razi, Peyman. „Development of the New Analytic Model for Sand Deposition Particles Downstream of a Fence“. Inventions 5, Nr. 1 (16.01.2020): 4. http://dx.doi.org/10.3390/inventions5010004.
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Movement of sand particles is a complicated phenomenon that occurs in nature. In this paper, the main goal is to provide an analytic model for the deposition profile of sand particles downstream of a fence. The analytic model was derived with respect to governing equations and shear flows for upstream and downstream regions. In this approach, we obtain a new expression for the downstream velocity of the fence, which allows for the determination of potential areas of deposition particles by assuming a log-normal distribution profile. A discrete-phase flow (DPM) was used to inject particles in the simulation domain. The DPM gives capabilities to capture spatiotemporal velocities components, as we can define the probability of deposition particles in the downstream of the fence. The proposed model was validated with a numerical model and experimental results. The comparison with field data and numerical results shows that the deposition profile is in acceptable agreement. With some assumptions and modifications about the properties of particles, the results of this research can be extended to snow accumulation downstream of a fence.
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Wu, Guorong, und Yanggui Li. „DPM Simulations of A-Type FCC Particles’ Fast Fluidization by Use of Structure-Dependent Nonlinear Drag Force“. Processes 9, Nr. 9 (02.09.2021): 1574. http://dx.doi.org/10.3390/pr9091574.
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Nonlinear drag force has been a research frontier in complex gas-solid systems. The literature has reported that the commonly-used drag correlations often overestimate drag force and, thus, cause unrealistic homogeneous flow structures in gas-solid fluidized beds of fine particles. For solving this problem, the structure-dependent drag model, derived from energy-minimization multi-scale approach, is used in discrete simulations of fluid catalytic cracking particles in a small riser. The gas phase is dealt with by computational fluid dynamics. Particles are considered as a discrete phase and described by Newton’s second law of motion. Gas-particle phases are coupled according to Newton’s third law of motion. Simulations show that use of structure-dependent drag model results in drag reduction, the effect of which is not so apparent as that in simulations of the two fluid model. The particle clustering tendency, however, is more distinct and leads to more heterogeneous flow structures in riser flow with a much greater amplitude of outlet solid flux fluctuations. Moreover, the behaviors of particle and gas back-mixing can be captured in the present simulations, which was supported by past simulations and experimental data. The simulation time resolution is discussed. The spring constant can be artificially brought down for safe setting of larger time step when modelling the collision process between fine particles with a higher calculation load. To appropriately mimic the continuous decay of van der Waals force may, however, need a much smaller time step. There is also an obvious effect of space resolution on simulations. When using a grid size smaller than 3 times the particle diameter, the simulated clusters turn extraordinarily large, and the effect of gas-solid back-mixing turns insignificant.
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THORNTON, ANTHONY, THOMAS WEINHART, STEFAN LUDING und ONNO BOKHOVE. „MODELING OF PARTICLE SIZE SEGREGATION: CALIBRATION USING THE DISCRETE PARTICLE METHOD“. International Journal of Modern Physics C 23, Nr. 08 (August 2012): 1240014. http://dx.doi.org/10.1142/s0129183112400141.
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Over the last 25 years a lot of work has been undertaken on constructing continuum models for segregation of particles of different sizes. We focus on one model that is designed to predict segregation and remixing of two differently sized particle species. This model contains two dimensionless parameters: Sr, a measure of the segregation rate, and Dr, a measure of the strength of diffusion. These, in general, depend on both flow and particle properties and one of the weaknesses of the model is that these dependencies are not predicted. They have to be determined by either experiments or simulations. We present steady-state, periodic, chute-flow simulations using the discrete particle method (DPM) for several bi-disperse systems with different size ratios. The aim is to determine one parameter in the continuum model, i.e. the segregation Péclet number (ratio of the segregation rate to diffusion, Sr/Dr) as a function of the particle size ratio. Reasonable agreement is found; but, also measurable discrepancies are reported; mainly, in the simulations a thick pure phase of large particles is formed at the top of the flow. Additionally, it was found that the Péclet number increases linearly with the size ratio for low values, but saturates to a value of approximately 7.7.
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Zhu, Hongbo, Jie Su, Xuesen Wei, Zhaolong Han, Dai Zhou, Xun Wang und Yan Bao. „Numerical Simulation of Haze-Fog Particle Dispersion in the Typical Urban Community by Using Discrete Phase Model“. Atmosphere 11, Nr. 4 (14.04.2020): 381. http://dx.doi.org/10.3390/atmos11040381.
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The haze-fog particle dispersion in urban communities will cause serious health and environmental problems, which has aroused society attention. The aim of the present investigation is to reveal the underlying mechanisms of haze-fog particle dispersion via Computational Fluid Dynamics (CFD) method, and then to provide a groundwork for the optimal spatial arrangement of urban architecture. The Delayed Detached-eddy Simulation turbulence model (DDES) and Discrete Phase Model (DPM) are utilized to investigate the wind flow distribution and the particle dispersion around the building group. The numerical results show that the particle dispersion is dominated by the incoming wind flow, the layout of architectural space and the type and distribution of vortex. The ‘single body’ wake pattern and the vortex impingement wake pattern are identified in the wind flow field, which have different effects on the distribution of haze-fog particle. The cavity formed by the layout of the building group induces primary vortex and secondary vortex, which will make it more difficult for the particles entering the square cavity to flow out. Moreover, the concentration of the particle in the rear of the buildings is relatively low due the effect of attached vortices.
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Chen, Deng Feng, Xiao Dong Yang und Hai Yan Xiao. „Numerical Simulation of Particle Trajectory in Electrostatic Precipitator“. Applied Mechanics and Materials 568-570 (Juni 2014): 1743–48. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.1743.
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The performance of Electrostatic Precipitator (ESP) is significantly affected by complex flow distribution. Recent years, many numerical models have been developed to model the particle motion in the electrostatic precipitators. The computational fluid dynamics (CFD) code FLUENT is used in description of the turbulent gas flow and the particle motion under electrostatic forces. The gas flow are carried out by solving the Reynolds-averaged Navier-Stokes equations and turbulence is modeled by the k-ε turbulence model. The effect of electric field is described by a series equations, such as the electric field and charge transport equations, the charged particle equation, the charge conservation equation, the mass and momentum equations of gas, the mass and momentum equations of particle and so on. The particle phase is simulated by using Discrete Phase Model (DPM). The simulations showed that the particle trajectory inside the ESP is influenced by both the aerodynamic and electrostatic forces. The simulated results have been validated by the established data.
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Wang, Y. Q., Ming Rang Cao, Sheng Qiang Yang und Wen Hui Li. „Numerical Simulation of Liquid-Solid Two-Phase Flow Field in Discharge Gap of High-Speed Small Hole EDM Drilling“. Advanced Materials Research 53-54 (Juli 2008): 409–14. http://dx.doi.org/10.4028/www.scientific.net/amr.53-54.409.
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The flow field characteristics have a significant effect on the machining stability in high-speed small hole EDM drilling. Thus, Lagrangian discrete phase model (DPM) has been developed to simulate the gap liquid-solid two-phase flow field. The numerical calculation is based on the standard k-ε turbulent model, and the SIMPLEC algorithm is used in the simulation. All the governing equations are solved by software Fluent 6.2. Through numerical simulation, the pressure distribution, the velocity distribution of the dielectric liquid, traces of debris particles, and the debris particle concentration were obtained. The flow field characteristics under different pressures and drilling depths were obtained through simulations. Finally, experiments were carried out to investigate the effects of the flush velocity at exit obtained through simulation on material removal rate (MRR).
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Mei, Shu Xia, Jun Lin Xie, Feng He und Ming Fang Jin. „Numerical Simulations of Combustion and Decomposition Processes in Precalciner with Two Different Heights of Raw Meal Inlets“. Applied Mechanics and Materials 268-270 (Dezember 2012): 477–82. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.477.
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To reduce energy consumption, numerical simulations of combustion and decomposition processes in a precalciner were carried out with two different heights of raw meal inlets. In Euler coordinate system the gas phase is expressed with k-ε two-equation model, in Lagrange coordinate system the solid phase is expressed with discrete phase model (DPM), the chemical reaction is expressed with species transport model, and the radiation is expressed with P1 radiation model. The results show that when the raw meal inlets are near the jetting coal pipes, there is much better dispersing condition of CaCO3 but a much poorer coal combustion condition, resulting in a much higher CaCO3 decomposition rate but a lower coal burn-off rate than that when the raw meal inlets are far away from the jetting coal pipes. It is advised to install both the two heights of raw meal inlets in order to obtain not only high CaCO3 decomposition rate but also high coal burn-off rate.
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Mei, Shu Xia, Jun Lin Xie, Feng He und Ming Fang Jin. „Numerical Simulations of Combustion and Decomposition Processes in Precalciner with Two Types of Locations of Jetting Coal Pipes“. Applied Mechanics and Materials 235 (November 2012): 428–33. http://dx.doi.org/10.4028/www.scientific.net/amm.235.428.
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To reduce energy consumption, numerical simulations of combustion and decomposition processes in a precalciner were carried out with two types of locations of jetting coal pipes. In Euler coordinate system the gas phase is expressed with k-ε two-equation model, in Lagrange coordinate system the solid phase is expressed with discrete phase model (DPM), the chemical reaction is expressed with species transport model, and the radiation is expressed with P1 radiation model. For the base case the predicted burn-off rate of pulverized coal was 86%, and the decomposing rate of calcium carbonate was 92.9%, which are in accordance with actual measurement engineering data. The results show that when the jetting coal pipes are above the tertiary air inlet, the flow pattern of coal streams is more rational in the precalciner, being beneficial to the coal burn fully, resulting in a high temperature zone, around which the calcium carbonate decompose rapidly, than that when the jetting coal pipes are far away from the tertiary air inlet.
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Liu, Chang, Zuobing Chen, Weili Zhang, Chenggang Yang, Ya Mao, Yongjie Yu und Qiang Xie. „Effects of Blade Parameters on the Flow Field and Classification Performance of the Vertical Roller Mill via Numerical Investigations“. Mathematical Problems in Engineering 2020 (03.11.2020): 1–15. http://dx.doi.org/10.1155/2020/3290694.
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The vertical roller mill is an important crushing and grading screening device widely used in many industries. Its classification efficiency and the pressure difference determine the entire producing capacity and power consumption, respectively, which makes them the two key indicators describing the mill performance. Based on the DPM (Discrete Phase Model) and continuous phase coupling model, the flow field characteristics in the vertical roller mill including the velocity and pressure fields and the discrete phase distributions had been analyzed. The influence of blade parameters like the shape, number, and rotating speed on the flow field and classification performance had also been comprehensively explored. The numerical simulations showed that there are vortices in many zones in the mill and the blades are of great significance to the mill performance. The blade IV not only results in high classification efficiency but also reduces effectively the pressure difference in the separator and also the whole machine. The conclusions of the flow field analysis and the blade effects on the classification efficiency and the pressure difference could guide designing and optimizing the equipment structure and the milling process, which is of great importance to obtain better overall performance of the vertical roller mill.
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Zhang, Ma, Kim und Lin. „Numerical Analysis of Supersonic Impinging Jet Flows of Particle-Gas Two Phases“. Processes 8, Nr. 2 (05.02.2020): 191. http://dx.doi.org/10.3390/pr8020191.
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Supersonic impinging jet flows always occur when aircrafts start short takeoff and vertical landing from the ground. Supersonic flows with residues produced by chemical reaction of fuel mixture have the potential of reducing aircraft performance and landing ground. The adverse flow conditions such as impinging force, high noise spectrum, and high shear stress always take place. Due to rare data on particle-gas impinging jet flows to date, three-dimensional numerical simulations were carried out to investigate supersonic impinging jet flows of particle-gas two phases in the present studies. A convergent sonic nozzle and a convergent-divergent supersonic nozzle were used to induce supersonic impinging jet flows. Discrete phase model (DPM), where interaction with continuous phase and two-way turbulence coupling model were considered, was used to simulate particle-gas flows. Effects of different particle diameter and Stokes number were investigated. Particle mass loading of 10% were considered for all simulations. Gas and particle velocity contours, wall shear stress, and impinging force on the ground surface were obtained to describe different phenomena inside impinging and wall jet flows of single gas phase and gas-particle two phases.
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Xie, Jun Lin, und Shu Xia Mei. „Numerical Simulation of Gas-Solid Flow in a Precalciner of Cement Industry“. Materials Science Forum 575-578 (April 2008): 1234–39. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.1234.
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Precalciner, in which endothermic raw meal calcination and exothermic fuel combustion proceed simultaneously, is a key equipment in dry process of cement production. To increase the precalcination degree and reduce the energy consumption, more and more attentions have been paid on modeling gas-solid flow field in precalciners. However, most of them aimed at just qualitative studies lacking in necessary further quantitative analysis of precalciner performance parameters. In this paper, combining qualitative studies and quantitative analysis, the gas-solid flow field was carried out aiming at an actual precalciner under operational-based boundary conditions. In Euler coordinate system the gas phase is expressed with k-ε model, in Lagrange coordinate system the solid phase is expressed with Discrete Phase Model(DPM), and the random effects of turbulence on the particle dispersion is accounted for with Discrete Random Walk (DRW) model. The predicted gas velocity field agrees well with the measured result, and the calculated raw meal concentration distribution is consistent with the actul condition. The results predicted that there is a simple spraying-liked flow field in the precalciner, with not only a non-uniform particle dispersion condition but also a low solid residence-time and residence-time ratio between solid and gas.
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Wan, Chang Dong. „Numerical Simulation and Response Surface Optimization of Oil-Gas Separator“. Advanced Materials Research 466-467 (Februar 2012): 396–99. http://dx.doi.org/10.4028/www.scientific.net/amr.466-467.396.
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CFD (computational fluid dynamics) is a good method for simulation of the oil-gas separator. When the volume concentration is less than 10%, the oil particle tracks can be simulated by DPM （Discrete Phase Model）. The results show that the separation efficiency is obviously affected by the diameter of separator air-outlet, the diameter of separator oil-outlet, and the angle of separator cone. But the quantified analysis on separation efficiency is difficultly brought forward by CFD. RSM (response surface methods) can help to identify factors influencing the responses by experiments. Finally, the optimum responses and design parameters will be obtained altogether.
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Li, Linmin, Zhongqiu Liu, Maoxue Cao und Baokuan Li. „Large Eddy Simulation of Bubbly Flow and Slag Layer Behavior in Ladle with Discrete Phase Model (DPM)–Volume of Fluid (VOF) Coupled Model“. JOM 67, Nr. 7 (03.06.2015): 1459–67. http://dx.doi.org/10.1007/s11837-015-1465-x.
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Yao, Yongming, Xupeng Bai, Huiying Liu, Tianyu Li, Jianbo Liu und Guangli Zhou. „Solid Particle Erosion Area of Rotor Blades: Application on Small-Size Unmanned Helicopters“. Symmetry 13, Nr. 2 (22.01.2021): 178. http://dx.doi.org/10.3390/sym13020178.
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Rotor blades play an important role in unmanned helicopters, and it is of great significance to study the erosion of rotor blades. In this study, titanium alloy (Ti-4Al-1.5Mn) was used as the helicopter rotor blades’ surface material. The commercial software Ansys-Fluent 18.0 was mainly used to study the erosion of solid particles on the helicopter rotor blades. The moving mesh method and the discrete phase method (DPM) were used to construct an erosion model of the blades at different speeds (500, 1000, or 2000 rpm), and at different particle mass flow rates (0.5, 1, or 1.5 kg/s). The results show that the erosion of helicopter blades is mainly observed at the leading edge and at the tip of the blades. At different particle mass flow rates, greater particle mass flow rates lead to greater DPM erosion rates. As the blade speed increases, the maximum DPM erosion rate decreases, but the severely eroded area increases. Finally, the values of the severely eroded area of the helicopter rotor blades and the ratios of the severely eroded area growth are obtained through the image processing method.
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Zhang, Guang, Wei Wei Wang, Xiang Hui Su, Xiao Jun Li, Wen Hao Shen und Zhe Lin. „Numerical Studies of Particle-Gas Two-Phase Flowing through Microshock Tubes“. Shock and Vibration 2021 (15.02.2021): 1–12. http://dx.doi.org/10.1155/2021/6628672.
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Microshock tubes are always used to induce shock waves and supersonic flows in aerospace and medical engineering fields. A needle-free drug delivery device including a microshock tube and an expanded nozzle is used for delivering solid drug powders through the skin surface without any injectors or pain. Therefore, to improve the performance of needle-free drug delivery devices, it is significantly important to investigate shock waves and particle-gas flows induced by microshock tubes. Even though shock waves and multiphase flows discharged from microshock tubes have been studied for several decades, the characteristics of unsteady particle-gas flows are not well known to date. In the present studies, three microshock tube models were used for numerical simulations. One microshock tube model with closed end was used to observe the reflected shock wave and flow characteristics behind it. The other two models are designed with a supersonic nozzle and a sonic nozzle at the exit of the driven section, respectively, to investigate particle-gas flows induced by different nozzles. Discrete phase method (DPM) was used to simulate unsteady particle-gas flows and the discrete random walk model was chosen to record the unsteady particle tracking. Numerical results were obtained for comparison with those from experimental pressure measurement and particle visualization. Shock wave propagation was observed to agree well with experimental results from numerical simulations. Particles were accelerated at the exit of microshock tube due to the reservoir pressure induced by reflected shock wave. Both sonic and supersonic nozzles were underexpanded at the end of microshock tubes. Particle velocity was calculated to be smaller than gas velocity, which results from larger drag of injected particles.
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Li, Xiao Huo, Shu Ming Liu, Zhi Long Huang und Wei Du. „Study of the Effects of Shearer’ Kinematic Parameters on on-Way Distribution of Dust on Coal Face“. Applied Mechanics and Materials 127 (Oktober 2011): 400–405. http://dx.doi.org/10.4028/www.scientific.net/amm.127.400.
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In order to research the effects of shearer’ kinematical parameters on on-way distribution of dust on coal face, according to the theory of suspension gas-solid two-phase flow and the theory of cutting dust formation, mathematical model of on-way dust concentration was established, methods of determining parameters were given, dust migration was simulated by using the discrete phase model (DPM) in FLUENT, on-way distribution regularity of dust was found. According to calculation of the quantity of cutting dust at different hauling speed and different rotational speed of drum, dust migration was simulated and migration regularity was showed as follows: dust concentration of every point on a coal face increased as hauling speed decreased or rotational speed increased. In addition, with rotational speed increased, the position of concentration maximum moved a little along downwind.
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Wang, Xiaopeng, Shifu Zhu, Song Chen, Ning Ma und Zhe Zhang. „Proper Orthogonal Decomposition Analysis and Dispersion Characteristics of Resonant Acoustic Flow“. Shock and Vibration 2020 (04.03.2020): 1–13. http://dx.doi.org/10.1155/2020/5068042.
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The investigation on the flow field and mixing characteristics of resonant sound mixing is of great significance for the dispersion mixing of superfine materials. In order to simulate the flow field and dispersion characteristics of resonant acoustic mixing, a gas-liquid-solid three-phase flow model based on the coupled level-set and volume-of-fluid (CLSVOF) and discrete particle model (DPM) was established. The CLSVOF model solves the gas-liquid interface, and the DPM model tracks the particle position. Then, the particle image velocimetry (PIV) experiment was performed using a self-made resonance acoustic hybrid prototype under different oscillation accelerations, and the radial velocity distribution between the experiment and simulation was compared. Finally, the proper orthogonal decomposition (POD) is used to decompose the flow field under different oscillation accelerations and fill levels, and the energy distribution law and the energy structure of different scales are extracted. The results show that the energy of the instantaneous flow field of the resonant sound is mainly concentrated in the low-order mode, and a close relationship was revealed between the energy distribution law and dispersion behavior of particles. The larger the small-scale coherent structures distribute, the more energy it has and the more favorable it is for fast and uniform dispersion.
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Liu, Jinjin, Kai Liu, Tong Zhao und Zhuofei Xu. „A Three-Dimensional Simulation of Particle Distribution in a Separator and Structure Optimization with the Statistical Approach of Taguchi Method“. Mathematical Problems in Engineering 2018 (27.11.2018): 1–10. http://dx.doi.org/10.1155/2018/7439245.
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A three-dimensional numerical simulation combining discrete phase method (DPM) and porous media based on the theory of Euler-Lagrange has been employed to investigate particles distribution in a separator. The DPM model is applied to monitor the movement of individual particles and calculate the contact force between them in the separator. The simulation results display the migration feature of dust particles over time and the distribution of particles on the surface element in porous region and reveal that the flow field influences the distribution uniformity of the particles in porous area directly. Based on the analysis, the structure of separator is optimized by the Taguchi method. An orthogonal relation motion has been established. The optimal solution is achieved by the calculation of the weight relationship. The calculated optimal structure is evaluated by the signal to noise (SNR). The result reveals that the values of SNR in case are eligible. As a result, the research of the separator points out a useful and improvable method for the parameter optimization of structure design.
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Sheikh, Md Al Amin. „Numerical simulation of blood flow in Cerebral aneurysms using two-phase model“. Asian Journal Of Medical Technology 1, Nr. 1 (30.07.2021): 1–17. http://dx.doi.org/10.32896/ajmedtech.v1n1.1-17.
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ABSTRACT: Computational fluid dynamic (CFD) simulation techniques have played an essential role in simulating and understanding the initiation, growth, and rupture of cerebral aneurysms. Hemodynamic parameters are mainly used to examine the rupture risk status of cerebral aneurysms using blood flow CFD simulation. Blood was considered as single-phase flow model with both Newtonian and non-Newtonian to predict the rupture risk analysis. However, to better understand predicting the risk of cerebral aneurysm rupture, blood requires two-phase, such as plasma and red blood cells (RBCs), also known as erythrocytes. In this study, the two-phase blood flow model was solved by the discrete phase model (DPM) with Lagrangian approach, in which blood was modeled two-phase fluid as a continuous phase plasma and particulate phase RBCs. Three patient-specific aneurysm geometries have been selected to determine wall shear stress (WSS), oscillatory shear index (OSI), and relative residence time (RRT) with two-phase blood flow simulation. To analyze the velocity distribution inside the aneurysms, velocity streamlines and surface velocities were reported. The pulsatile blood flow simulation was performed for aneurysm geometries, where the mean inlet Reynolds number was calculated between 490 and 1370. The value of WSS, OSI, and RRT was quantified based on the Reynolds number. Reynolds number's minimum value indicates the low WSS, low OSI, and short RRT, and the maximum value of Reynolds number shows the high WSS, high OSI, and long RRT. The high WSS, high OSI, and long RRT, velocity streamlines distribution, surface velocity changes were determined with two-phase blood in aneurysm geometries, aneurysm geometry one and three are the medium and giant size saccular aneurysm may have a higher risk of rupture while aneurysm geometry two is medium size fusiform aneurysm has a lower risk of rupture. The two-phase blood flow model presents reasonable hemodynamic parameters that correlate with aneurysms rupture risk prediction.
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Doroshenko, Yaroslav, Julia Doroshenko, Vasyl Zapukhliak, Lyubomyr Poberezhny und Pavlo Maruschak. „MODELING COMPUTATIONAL FLUID DYNAMICS OF MULTIPHASE FLOWS IN ELBOW AND T-JUNCTION OF THE MAIN GAS PIPELINE“. Transport 34, Nr. 1 (16.01.2019): 19–29. http://dx.doi.org/10.3846/transport.2019.7441.
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The research was performed in order to obtain the physical picture of the movement of condensed droplets and solid particles in the flow of natural gas in elbows and T-junctions of the linear part of the main gas pipeline. 3D modeling of the elbow and T-junction was performed in the linear part of the gas main, in particular, in places where a complex movement of multiphase flows occurs and changes its direction. In these places also occur swirls, collisions of discrete phases in the pipeline wall, and erosive wear of the pipe wall. Based on Lagrangian approach (Discrete Phase Model – DPM), methods of computer modeling were developed to simulate multiphase flow movement in the elbow and T-junction of the linear part of the gas main using software package ANSYS Fluent R17.0 Academic. The mathematical model is based on solving the Navier–Stokes equations, and the equations of continuity and discrete phase movement closed with Launder–Sharma (k–e) two-parameter turbulence model with appropriate initial and boundary conditions. In T-junction, we simulated gas movement in the run-pipe, and the passage of the part of flow into the branch. The simulation results were visualized in postprocessor ANSYS Fluent R17.0 Academic and ANSYS CFD-Post R17.0 Academic by building trajectories of the motion of condensed droplets and solid particles in the elbow and T-junction of the linear part of the gas main in the flow of natural gas. The trajectories were painted in colors that match the velocity and diameter of droplets and particles according to the scale of values. After studying the trajectories of discrete phases, the locations of their heavy collision with the pipeline walls were found, as well as the places of turbulence of condensed droplets and solid particles. The velocity of liquid and solid particles was determined, and the impact angles, diameters of condensed droplets and solid particles in the place of collision were found. Such results provide possibilities for a full and comprehensive investigation of erosive wear of the elbow and T-junction of the linear part of the gas main and adjacent sections of the pipeline, and for the assessment of their strength and residual life.
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Chen, Gujun, Qiangqiang Wang und Shengping He. „Assessment of an Eulerian multi-fluid VOF model for simulation of multiphase flow in an industrial Ruhrstahl–Heraeus degasser“. Metallurgical Research & Technology 116, Nr. 6 (2019): 617. http://dx.doi.org/10.1051/metal/2019049.
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An Eulerian multi-fluid VOF model, the coupling of the Eulerian model and the “VOF” interface tracking method, offered by ANSYS Fluent has been first applied to investigate the complex multiphase flow in an industrial Ruhrstahl–Heraeus (RH) degasser. The idea of this study is to use the Eulerian model in the regions of the domain where the argon bubbles are dispersed in molten steel; in the regions of the domain where the sharp interfaces between the steel and slag or argon are of interest, the “VOF” method is adopted. The calculated flow characteristic, mixing time and circulation flow rate of molten steel in the RH degasser agree well with the observations reported in literature. Compared with the widely accepted Eulerian method and the discrete phase model–volume of fluid (DPM–VOF) coupled method, the Eulerian multi-fluid VOF model demonstrates the suitability for modeling the multiphase flow in the RH degasser where both dispersed and sharp interfaces are present.
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Sakin, Ali, und Irfan Karagoz. „Numerical prediction of short-cut flows in gas-solid reverse flow cyclone separators“. Chemical Industry and Chemical Engineering Quarterly 23, Nr. 4 (2017): 483–93. http://dx.doi.org/10.2298/ciceq161009002s.
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The effect of operational and geometrical parameters on the short-cut flow in cyclone separators has been investigated computationally using the Reynolds stress model (RSM). The motion of solid particles in the flow field was simulated using the Eulerian-Lagrangian approach with one way discrete phase method (DPM). Eleven cyclones with different cone tip diameters, vortex finder lengths and diameters were studied and the simulation results were analyzed in terms of velocity fields, pressure drops, cut-off diameters and short-cut flows. The numerical simulation was verified with the published experimental results. The results obtained demonstrate that all three parameters, particularly, vortex finder diameter, have significant effects on the cut-off diameter (collection efficiency), the short-cut flow and the pressure drop.
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Hoornahad, H., Eddy A. B. Koenders und Klaas van Breugel. „Towards a Model for Fresh Granular-Paste Systems Based on Discrete Element Method“. Key Engineering Materials 452-453 (November 2010): 569–72. http://dx.doi.org/10.4028/www.scientific.net/kem.452-453.569.
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Modelling the rheological behaviour of fresh granular-paste systems is the main aim of this study. The research approach is based on a conceptual idea where the paste-interaction system is explicitly modelled by an interactive two phase particle system. As a first approach the cohesive force-displacement interaction was measured for two ideally shaped glass particles bridged by water. Later on, the water was replaced by cement paste and the attraction force acting on the glass particles was measured for increasing inter-particle distances. The results gave a very good impression of the cohesive forces acting on a granular paste system employed by the cementations material in its fresh state. The Discrete Element Method (DEM) is one of the computational techniques that is applied to simulate the granular-paste system. With this method, the fresh granular-paste system is divided into two phases (aggregate/paste) and is modelled by a single-phase or a double-phase system of DEM elements. At the first step, the interaction forces of the particle-paste system are compared with the experimental results achieved from the particle-liquid measurements and expressed as an explicit function based on local geometrical and physical parameters. Modelling and experimental results show good agreement.
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Huang, Xian Jia, Xi Shi Wang, Jia Lu, Zhong Jun Ding und Guan Xuan Liao. „An Experimental and Computational Study of Interaction between Water Mist and Gas Jet Flame“. Applied Mechanics and Materials 130-134 (Oktober 2011): 1720–24. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.1720.
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The experiment on gas jet flame extinguishing with water mist in open space was conducted in this paper. On the basis of experimental result, the process of the flame extinguishment can be classified into two categories:1) when fuel flow rate is small, the gas jet flame can be suppressed and extinguished quickly; 2) When fuel flow is large, the flame lifts from the attached position at the burner exit after suppressed by the water mist. FLUENT is used to simulate the interaction of water mist with gas jet flame. The Eddy-dissipation model (EDM) is used for combustion of flame. the water mist is simulated by Discrete Phase Model (DPM).The simulated results agree well with the experimental results. To some extent, EDM is suitable for simulating the interaction of water mist with a turbulent gas jet flame.
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Feng, Lianghua, Xiangwei Liao, Kun Liu, Wei Kang, Peng Han, Guangqiang Liu, Zhonghua Sheng, Xichen Shui, Dongheng Zhang und Wenlei Lin. „Numerical Simulation of Multiphase Flow Behavior in Hot Metal Ladle Desulfurization with Bottom Powder Injection and Electric Field“. Mathematical Problems in Engineering 2019 (29.11.2019): 1–8. http://dx.doi.org/10.1155/2019/3157040.
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A computation fluid-coupled discrete phase model (CFD-DPM) was used to predict the motion characteristics of gas, particle, and liquid phases in the hot metal ladle. The influence of different voltage loading modes, voltage values, and powder injection speeds on the particle motion trail was investigated, while the effects on the particle concentration maximum difference in the stagnation region were discussed. The optimal injection and voltage parameters were proposed. The results are shown as follows: the loading voltage before injection is beneficial to the diffusion of particles in the molten pool. With the increase of voltage and injection speed, the distribution of particles in the upper part of the molten iron tends to be uniform. The bottom of the ladle is the stagnation region. Optimum voltage and injection speed were determined. Under the optimum conditions, particles are evenly dispersed and the particle concentration difference in the stagnation region is small. This research work will benefit greatly to the hot metal ladle desulfurization technology.
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Zhu, Hang, Hongze Li, Cui Zhang, Junxing Li und Huihui Zhang. „Performance Characterization of the UAV Chemical Application Based on CFD Simulation“. Agronomy 9, Nr. 6 (12.06.2019): 308. http://dx.doi.org/10.3390/agronomy9060308.
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Battery-powered multi-rotor UAVs (Unmanned Aerial Vehicles) have been employed as chemical applicators in agriculture for small fields in China. Major challenges in spraying include reducing the influence of environmental factors and appropriate chemical use. Therefore, the objective of this research was to obtain the law of droplet drift and deposition by CFD (Computational Fluid Dynamics), a universal method to solve the fluid problem using a discretization mathematical method. DPM (Discrete Phase Model) was taken to simulate the motion of droplet particles since it is an appropriate way to simulate discrete phase in flow field and can track particle trajectory. The figure of deposition concentration and trace of droplet drift was obtained by controlling the variables of wind speed, pressure, and spray height. The droplet drifting models influenced by different factors were established by least square method after analysis of drift quantity to get the equation of drift quantity and safe distance. The relationship model, Yi(m), between three dependent variables, wind speed Xw(m s−1), pressure Xp(MPa) and spray height Xh(m), are listed as follows: The edge drift distance model was Y1 = 0.887Xw + 0.550Xp + 1.552Xh − 3.906 and the correlation coefficient (R2) was 0.837; the center drift distance model was Y2 = 0.167Xw + 0.085Xp + 0.308Xh − 0.667 and the correlation coefficient (R2) was 0.774; the overlap width model was Y3 = 0.692xw + 0.529xp + 1.469xh − 3.374 and the correlation coefficient (R2) was 0.795. For the three models, the coefficients of the three variables were all positive, indicating that the three factors were all positively correlated with edge drift distance, center drift distance, and overlap width. The results of this study can provide theoretical support for improving the spray quality of UAV and reducing the drift of droplets.
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Tavakoli, Keivan, Hossien Montaseri, Pourya Omidvar und Stefania Evangelista. „Numerical simulation of sediment transport in a U-shaped channel with lateral intake: Effects of intake position and diversion angle“. International Journal of Modern Physics C 30, Nr. 09 (September 2019): 1950071. http://dx.doi.org/10.1142/s0129183119500712.
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In this work, the mechanism of sediment transport in a U-shaped channel with a lateral intake is investigated experimentally and numerically, together with the processes of sediment entry into the intake itself and formation of bed topography. Dry sediment is injected into a steady flow in a rigid channel with a bend and sediment particles are traced in time. In order to validate the numerical model, the three components of the flow velocity, as well as the sediment path in time and the diverted sediment ratios, are measured experimentally. A numerical Discrete Phase Model (DPM) is then applied to study the effect of the intake position and diversion angle on the sediment transport mechanism in the bend. The DPM has, in fact, the capability of specifying for each particle its position relative to a reference time and space and, thereby, it is used in this study to analyze the phenomenon evolution and determine the sediment particles diverted into the intake. The comparison between the experimental data and the DPM numerical results shows a good agreement. In order to investigate the mechanism of sediment transport and to evaluate the percentage of the diverted sediments, a parametric study is then conducted through the numerical model, with different positions of the outer bend of the channel, diversion angles of the lateral intake and diversion discharge ratios. The results show that the mechanism of sediment entry into the lateral intake is affected by the diversion discharge ratio. For low discharge ratios, the mechanism of sediment entry to the lateral intake only consists of continuous entrance from the upstream edge of the intake. With the increase of the discharge ratio, it consists of a continuous entrance from the downstream edge and a periodic entrance from the upstream edge of the intake. The DPM results show that, for all diversion discharge ratios, the minimum percentage of sediment entered into the lateral intake corresponds to the position of 120∘ and diversion angle equal to 50∘.
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Zhang, Xiaobin, Weibing Zhu, Lei Qian und Miao Li. „Research on Performance Prediction Model of Impeller-Type Breather“. Applied Sciences 9, Nr. 17 (26.08.2019): 3504. http://dx.doi.org/10.3390/app9173504.
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To investigate the characteristics of separation and resistance of an impeller-type breather in an aeroengine lubrication system, orthogonal test design is used in calculation of the operating condition. Also, phase coupling of the RNG(Renormalization Group) k − ε model and the DPM model (Discrete Phase Model) is used in calculating the selected operating condition. Through analysis of the results, combined with dimensional analysis, it shows the significance of various influencing factors and the optimal level. Based on this, a general formed dimensionless group equation is established for comprehensive separation efficiency, breather separation efficiency, and ventilation resistance. Also, through the least squares method, the performance prediction model of the breather is obtained considering five operating conditions and six structural parameters. The theoretical calculation of separation efficiency and ventilation resistance of an impeller-type breather can be performed. The results show that: the main factors affecting the separation efficiency are the rotating speed and the number of impeller blades; the main factors affecting the ventilation resistance are the ventilation rate and the diameter of the vent hole; the variation trends of the calculated values of the performance prediction model and the experimental values are consistent. The mean error of the comprehensive separation efficiency is 0.97% and the mean error of the ventilation resistance is 11.73%. The calculated values and the experimental values remain consistent, which proves that this performance prediction model can provide references to the assessment and the design of an impeller breather.
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Zhang, Min, Shidong Fan, Hanhua Zhua und Sen Han. „Numerical Simulation of Solid-Fluid 2-Phase-Flow of Cutting System for Cutter Suction Dredgers“. Polish Maritime Research 25, s2 (01.08.2018): 117–24. http://dx.doi.org/10.2478/pomr-2018-0082.
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Abstract The study of the flow characteristics of the solid-fluid two phase flow in the cutter suction dredger is very important for exploring the slurry formation mechanism and optimizing the operational parameters. In this study, standard k-ε model and Multiple Reference Frame are applied to numerically simulate flow field in and around the cutting system, then with the steady convergent result of the simulation as the initial condition, Discrete Phase Mode is used to solve the particle motion equation by fully coupling the continuous phase and the particles. The influence of suction flow velocity and cutter’s rotating speed on particles suction are analyzed, and effectively suctioned particles numbers are also quantitatively studied. The simulation result shows that the DPM model is able to simulate the movement of particles in and around the cutter suction dredger’s cutting system, in the fluid flow filed velocity vector and pressure distribution on different planes show different characteristics, and under higher suction velocity and lower cutter rotating speed more particles are suctioned into the suction inlet. The results can help better understand flow characteristics of solid-fluid 2-phase-flow of cutter suction dredger’s cutting system, and provide theoretical support for relative system design and operational parameters optimization.
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Shi, Mingming, Yunjie Ruan, Binxin Wu, Zhangying Ye und Songming Zhu. „Performance evaluation of Hydrodynamic Vortex Separator at different hydraulic retention times applied in Recirculating Biofloc Technology system“. Transactions of the ASABE 60, Nr. 5 (2017): 1737–47. http://dx.doi.org/10.13031/trans.12415.
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Abstract. Recirculating biofloc technology (RBFT) has been gradually acknowledged for its positive effect on the control of biofloc concentration using a hydrodynamic vortex separator (HDVS). To operate an RBFT system at maximum performance, the removal efficiency of an HDVS at different hydraulic retention times (HRTs) must be fully predictable. Hence, a numerical study of the fluid flow and particle dynamics was performed to characterize the performance of an HDVS at varying HRTs. First, flow simulation was conducted to determine an economical mesh size at an HRT of 248 s. Then, with respect to the total suspended solids (TSS) in the RBFT system and the physical properties of the flocs, two-way coupling of the dense discrete phase model (DDPM) and discrete element model (DEM) methods was used to predict floc tracking in an HDVS. Additionally, the Reynolds averaged Navier-Stokes (RANS) equations with the Reynolds stress turbulence model (RSM) were solved using the finite volume method based on the semi-implicit method pressure-linked equations (SIMPLE) pressure correction algorithm in the computational domain. Finally, pilot-scale studies were conducted to verify the simulation models. Based on the simulation results, floc management in an RBFT system is briefly discussed. Due to limited research on the numerical simulation and operating conditions of an HDVS in an RBFT system, this article describes an original investigation of the modeling approach. Keywords: Computational fluid dynamics, Dense discrete phase model, Discrete element model, Floc management, Flow field, Removal efficiency, Total suspend solids.