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Numerical Simulations of Liquid-Solid Flows in A vertical pipe by MPS-DEM Coupling Method

China Ocean Engineering 2022年第4期36卷 542-552页

作者： XIE Feng-ze MENG Qing-jie WAN De-cheng Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Wuhan Second Ship Design and Research Institute Wuhan 430205China

In the process of deep-sea mining,the liquid-solid flows in the vertical transportation pipeline are very complex.In the present work,an in-house solver MPSDEM-SJTU based on the improved MPS and DEM is developed for the simulation of hydraulic conveying.Firstly,three examples including the multilayer cylinder collapse,the Poiseuille flow and two-phase dam-break are used to validate the precision of the DEM model,the pipe flow model and MPS-DEM coupling model,respectively.Then,the hydraulic conveying with coarse particles in a vertical pipe is simulated.The solid particle distribution is presented and investigated in detail.Finally,the coupling method is successfully applied for the simulation of the liquid-solid flows in a vertical pipe with rotating blades,which shows the stability of the solver under rotating boundary conditions.This fully Lagrangian model is expected to be a new approach for analyzing hydraulic conveying.

关键词： liquid-solid flows MPS DEM vertical pipe rotating boundary conditions

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Preparation of Semisolid A356 Alloy Feedstock Cast via a pipe Consisting of Partial Inclined and Partial vertical Sections

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Journal of Materials Science & Technology 2009年第2期25卷 273-276页

作者： Xiaorong Yang Weimin Mao School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering Taiyuan University of Science and Technology Taiyuan 030024 China

In the present work, the microstructures of A356 feedstock cast via a pipe consisting of partial inclined and partial vertical sections were investigated. The experimental results indicate that semisolid feedstock with ideal microstructures can be obtained at higher temperatures 645℃ and above by the proposed process, and the solid shell inside the pipe can be avoided at the optimum pouring temperature. Thus the process is attractive for industrial applications. The slanted angle of inclined section has an influence on the optimum pouring temperature. That is, the bigger the slanted angle, the higher the optimum pouring temperature, but accordingly, the greater the possibility of solid shell occurring inside the pipe. Therefore, small slanted angle should be considered first on the premise of ensuring a certain nucleation. The formation of semisolid feedstock is owed to the coactions of wall nucleation and stirring resulting from fluid flow. The inclined section greatly affects nucleation, and the vertical section has an important effect on both nucleation and generating stirring.

关键词： Semisolid Microstructure Inclined pipe vertical pipe Primary α-Al

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A Comparative Study of Closure Relations for CFD Modelling of Bubbly Flow in a vertical pipe

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Open Journal of Fluid Dynamics 2021年第2期11卷 98-134页

作者： Geoffrey S. Gray Scott J. Ormiston Department of Mechanical Engineering University of Manitoba Winnipeg Canada

Commercial code CFX was used to examine the performance of a two-fluid model to predict the details of upward isothermal bubbly flow of air and water in a vertical pipe. The model equations are volume-averaged Navier-Stokes equations that require closure models for interfacial forces and bubble-induced turbulence effects. Two-equation SST and k-epsilon RANS turbulence models were also used. A parametric study of closure models included both standard options in CFX and previously published novel closure models that were implemented with user-defined functions. The CFD simulations were compared with two cases from the MTLoop experiments by Lucas et al. at the Helmholtz-Zentrum Dresden Rossendorf: one with wall-peak void fraction profile (MT039), and another with a core-peak void fraction profile (MT118). The effect of changing the drag force closures was not significant for the set examined. Poor predictions were found when the lift force and wall lubrication models were incompatible in magnitude. There was no significant effect of changing the liquid phase turbulence model. Changing the bubble-induced turbulence models, however, had a significant impact on the radial void fraction profile. The novel wall force from Lubchenko et al. at the Massachusetts Institute of Technology significantly improved the prediction of the near wall void fraction in the wall peak profile.

关键词： Two-Phase Flow Bubbly Numerical Analysis vertical pipe

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On the Influence of Vortex-Induced Resistance on Oil-Shale Particle-Slurry Flow in vertical pipes

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Fluid Dynamics & Materials Processing 2021年第2期17卷 413-426页

作者： Li-an Zhao Tieli Wang College of Mining Liaoning Technical UniversityFuxin123000China pipeline Engineering Institute Wuhan Design and Research Institute of China Coal Technology and Engineering GroupWuhan430064China

The transportation in vertical pipelines of particle slurry of oil shale has important applications in several fields(marine mining,hydraulic mining,dredging of river reservoir,etc.).However,there is still a lack of information about the behavior of coarse particles in comparison to that of fine particles.For this reason,experiments on the fluidization and hydraulic lifting of coarse oil shale particles have been carried out.The experimental data for three kinds of particles with an average size of 5 mm,15 mm and 25 mm clearly demonstrate that vortices can be formed behind the particles.On this basis,a vortex resistance factor K is proposed here to describe this effect.A possible correlation law is defined by means of a data fitting method accordingly.This law is validated by an experiment employing particles with an average size of 3.4 mm.The vortex resistance factor K results in a reduction of the speed of solid particles and an increase in the sliding speed as well as a decrease in the hydraulic gradient.As a result,using this factor,the calculation of the solid particle speed and hydraulic gradient can be made more accurate with respect to measured values.

关键词： Coarse particle hydraulic gradient vertical pipe fluidization

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Methods for Reducing Seed Damage in the Technological Process of Cotton Processing

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Engineering（科研） 2022年第3期14卷 119-130页

作者： Muradov Rustam Isakhanov Khamidullo Khosimov Khusanboy Namangan Institute of Engineering and Technology Namangan Uzbekistan

The article describes the transfer of cotton to the next technological process while preserving its natural properties during the initial processing process. The analysis of methods of reducing impact forces when remo... 详细信息

关键词： Cotton Pneumatic Transport Separator Fan pipe Cyclone Stone Holder Auger Solenoid vertical pipe Blade Drum Cleaner Mesh Surface Shaft Vacuum Valve Discharge-Separator Volumetric

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