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flow characteristics of Grains in a Conical Silo with a Central Decompression Tube Based on Experiments and DEM Simulations

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Computer Modeling in Engineering & Sciences 2021年第6期127卷 855-873页

作者： Huinan Sun Siqiang Wang Zhuoqing Zhang Chaoyong Xia Xu Chen COFCO Research&Engineering(Zhengzhou)Co. Ltd.Zhengzhou450001China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian116023China

Grains are widely present in industrial productions and processing,and are stored in silos.In the silo,auxiliary structures are added to achieve efficient production.However,little effort has been devoted to the influence of the internal structure of the silo on the granular flow.In this work,a silo with a central decompression tube is studied through experimental measurements and discrete element methods.Then,the influences of the central decompression tube on the flow behavior of grains and wall pressure are analyzed.Results show that the grains are in mass flow in the silo without a central decompression tube,while the grains are in funnel flow in the silo with a central decompression tube.Moreover,regardless of whether there is a central decompression tube in the silo,the maximum pressure appears at the top of the conical silo.In the lower part of the silo,the wall pressure of the silo with a central decompression tube is lower than that of the silo without a central decompression tube.Therefore,a silo with a central decompression tube is more conducive to grain storage and discharge than a silo without a central decompression tube.

关键词： Discrete element method experimental measurements central decompression tube flow characteristics wall pressure

flow characteristics and Inclusion Removal in a Ten-strand Continuous Casting Tundish:Physical Modelling and Industrial Trials

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Journal of Iron and Steel Research(International) 2016年第2期23卷 92-97页

作者： Shu-guo ZHENG Miao-yong ZHU Ye-lian ZHOU Wang SU School of Metallurgy Northeastern University

The flow characteristics and inclusion removal in a ten-strand continuous casting tundish were investigated with physical modelling and industrial trials. The results show that, among the strands, the strand with the mini mum dimensionless time of the first appearance of tracer at the tundish exit appears to be the worst one for inclusion removal, while the strand with the maximum dimensionless mean residence time shows the best inclusion removal efficiency. The inclusion number decreases with increasing inclusion size for all strands. The inclusion number distri bution among strands is the same for all inclusion sizes and the descending order of inclusion number is basically con sistent with the ascending order of dimensionless mean residence time among individual strands. However, when the strand with the minimum dimensionless time of the first appearance of tracer at the tundish exit is not the same one with the minimum dimensionless mean residence time, the former seems to be inferior to the latter for inclusion re moval.

关键词： multistrand continuous casting tundish flow characteristics inclusion removal physical modelling in-dustrial trial

flow characteristics in a rotor-stator cavity with cooling air inlet at low radius

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航空动力学报 2015年第4期30卷 775-783页

作者： CAI Xu LUO Xiang ZHAO Xi XUGuo-qiang CAI Jun National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power Engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China Dalian Airforce Department of Information Network Communicaiton Non-Commissioned Office Academy Dalian Liaoning 116600 China Guizhou Aero-Engine Research Institute Aviation Industry Corporation of China Guiyang 550081 China

Experiments were conducted on a typical rotor-stator system where air entered through an annular slot at low radius and flowed out of the cavity axially through a rim seal between the rotor and the stator.For the seal in this rotor-stator system,the stationary shroud overlapped the rotating one.Pressure distributions at the stator surface and flow resistance coefficients of the rotor-stator cavity with a maximum gap of 67mm were measured under different dimensionless mass flow rates from 1.32×104 to 4.87×104 with a large range of rotational Reynolds numbers from 0.418×106 to 2.484×106.The results show that pressure on the stator surface decreases with the increase of rotational Reynolds number when the dimensionless mass flow rate is below 1.3×104;when the dimensionless mass flow rate is above 3.034×104,the trend reverses.This is the so-called"pressure inversion effect".However,dimensionless pressure does not show the same changes when rotational dynamic pressure is chosen as the denominator.The resistance coefficient of the rotor-stator cavity is determined by the dimensionless mass flow rate and rotational Reynolds number;for practical application,the resistance coefficient can also be estimated by the turbulent flow parameter in the range of turbulent parameter from 0.1to 1.6.

关键词： cooling system rotor-stator system flow characteristics pressure distribution resistance coefficient

CFD-DEM investigation into flow characteristics in mixed pulsed fluidized bed under electrostatic effects

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Particuology 2022年第7期20卷 100-112页

作者： Hongwei Li Lei Wang Changhe Du Wenpeng Hong School of Energy and Power Engineering Northeast Electric Power UniversityJilin 132012China

Static electricity has an important effect on gas–solid fluidized bed reactor fluidization performance.In the process of fluidization,electrostatic interaction between particles will obviously accelerate particle agglomerate formation,which consequently reduces the fluidization performance.Pulsed gas flow injection is an efficient method to enhance particle mixing,thereby weakening the occurrence of particle agglomerate.In this study,the two-dimensional hybrid pulsed fluidized bed is established.The flow characteristics are studied by using the coupled CFD-DEM numerical simulation model considering electrostatic effects.Influences of different pulsed frequencies and gas flow ratios on fluidized bed fluidization performance are investigated to obtain the optimal pulsed gas flow condition.Results show that in the presence of static electricity,the bubble generation position is lower,which is conducive to the particle flow.Pulsed gas flow can increase the particle velocity and improve the diffusion ability.The bubble generation time is different at different frequencies,and the frequency of 2.5 Hz has the most obvious effect on the flow characteristics.Different gas flow ratios have significant impacts on the particle movement amplitude.When the pulse gas flow accounts for a large ratio,the particle agglomerate tends to be larger.Therefore,in order to improve the fluidization effect,the ratio of pulsed gas flow to stable gas flow should be appropriately reduced to 0.5 or less.

关键词： Mixed pulsed fluidized bed CFD-DEM Electrostatic effects flow characteristics

Analysis of Gas-Solid flow characteristics in a Spouted Fluidized Bed Dryer by Means of Computational Particle Fluid Dynamics

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Fluid Dynamics & Materials Processing 2020年第4期16卷 813-826页

作者： Hongming Zhou Haozheng Gao Zheng Fang Jiangxin Yang Mingge Wu College of Mechanical and Electrical Engineering Wenzhou UniversityWenzhou325035China Zhejiang Canaan Technology Co. Ltd.Wenzhou325000China School of Mechanical Engineering Zhejiang UniversityHangzhou310027China

In order to grasp the particle flow characteristics and energy consumption of industrial fluidized spouted beds,we conduct numerical simulations on the basis of a Computational Particle Fluid Dynamics(CPFD)approach.In particular,the traction model of Wen-Yu-Ergun is used and different inlet conditions are considered.Using a low-speed fluidizing gas,the flow state of the particles is better and the amount of particles accumulated at the bottom of the bed wall becomes smaller.For the same air intake,the energy loss of a circular nozzle is larger than that of a square nozzle.

关键词： Spouted fluidized bed CPFD flow characteristics numerical simulation

Experimental Study on the flow characteristics of a Plate with a Mechanically Choked Orifice

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Fluid Dynamics & Materials Processing 2021年第1期17卷 97-107页

作者： Ming Liu Xingkai Zhang Dong Wang State Key Laboratory of Multiphase flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China Petroleum Engineering Technology Research Institute of Shengli Oilfield Company SINOPECDongying257000China Shandong Key Laboratory of Heavy Oil Production Technology Shengli Oilfield CompanySINOPECDongying257000China Petroleum Engineering College Yangtze UniversityWuhan430100China

The mechanically choked orifice plate (MCOP) is a new type of device for flow control by which choking conditionsfor incompressible fluids can be obtained with relatively small pressure losses. Given the lack of relevant results anddata in the literature, in the present study, we concentrate on the experimental determination of the flow coefficientfor the annular orifice, the pressure distribution in the MCOP, and the characteristics of the choked flow itself. Asconfirmed by the experimental results, the Reynolds number, the orifice plate thickness, the plug taper, and theeccentricity have an obvious influence on the aforementioned flow coefficient. The pressure drop in the MCOPis mainly generated near the orifice plate, and the pressure upstream of the orifice plate is slightly reduced in theflow direction, while the pressure downstream of the orifice plate displays a recovery trend. The choked flow rateof the MCOP can be adjusted by replacing the spring with a maximum flow control deviation of 4.91%.

关键词： Mechanical choked orifice plate flow control flow coefficient flow characteristics

Influence of matrix physical properties on flow characteristics in dual network model

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Petroleum Science 2023年第4期20卷 2244-2252页

作者： Chen-Chen Wang Yong-Fei Yang Deng-Lin Han Miao-Miao Su Rong-Rong Hu Cooperative Innovation Center of Unconventional Oil and Gas Yangtze UniversityWuhan430100HubeiChina Laboratory of Reservoir Microstructure Evolution and Digital Characterization Yangtze UniversityWuhan430100HubeiChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina School of Geosciences Yangtze UniversityWuhan430100HubeiChina College of Resources and Environment Yangtze UniversityWuhan430100HubeiChina School of Petroleum Engineering Yangtze UniversityWuhan430100HubeiChina

The tight oil formation develops with microfractures and matrix pores,it is important to study the influence of matrix physical properties on flow characteristics.At first,the representative fracture and matrix samples are selected respectively in the dual media,the fracture and matrix digital rocks are constructed with micro-CT scanning at different resolutions,and the corresponding fracture and matrix pore networks are extracted,respectively.Then,the modified integration method is proposed to build the dual network model containing both fracture and matrix pore-throat elements,while the geometric-topological structure equivalent matrix pores are generated to fill in the skeleton domain of fracture network,the constructed dual network could describe the geometric-topological structure characteristics of fracture and matrix pore-throat simultaneously.At last,by adjusting the matrix pore density and the matrix filling domain factor,a series of dual network models are obtained to analyze the influence of matrix physical properties on flow characteristics in dual-media.It can be seen that the matrix system contributes more to the porosity of the dual media and less to the permeability.With the decrease in matrix pore density,the porosity/permeability contributions of matrix system to dual media keep decreasing,but the decrease is not significant,the oil-water co-flow zone decreases and the irreducible water saturation increases,and the saturation interval dominated by the fluid flow in the fracture keeps increasing.With the decrease in matrix filling domain factor,the porosity/permeability contributions of matrix system to dual media decreases,the oil-water co-flow zone increases and the irreducible water saturation decreases,and the saturation interval dominated by the fluid flow in the fracture keeps increasing.The results can be used to explain the dual-media flow pattern under different matrix types and different fracture control volumes during tight oil production.

关键词： Network integration Dual media flow characteristics Matrix pore density Matrix filling domain

CFD-Based Evaluation of flowand Temperature characteristics of Airflow in an Aircraft Cockpit

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Computer Modeling in Engineering & Sciences 2022年第2期129卷 701-721页

作者： Xiaosai Duan Suihuai Yu Jianjie Chu Dengkai Chen Zhaojing Su Key Laboratory of Industrial Design and Ergonomics Ministry of Industry and Information TechnologyNorthwestern Polytechnical UniversityXi’an710072China

The rational design of airflow distribution is of great importance for comfort and energy conservation.Several numerical investigations of flow and temperature characteristics in cockpits have been performed to study the distinct airflow distribution.This study developed the coupled heat transfer model of radiation,convection,and heat conduction for the cockpit flight environment.A three-dimensional physical model was created and a shear stress transfer(SST)k-w turbulence model was well verified with a high prediction accuracy of 91%for the experimental data.The strong inhomogeneous flow and temperature distribution were captured for various initial operating conditions(inlet temperature,inlet pressure,and gravitational acceleration).The results indicated that the common feature of the flow field was stable in the middle part of the cockpit,while the temperature field showed a large temperature gradient near the cockpit’s top region.It was also found that there was remarkable consistency in the distributed features,regardless of the applied initial operating conditions.Additionally,the mass flux and the top heat source greatly affected the flow and temperature characteristics.This study suggests that an optimized operating condition does exist and that this condition makes the flow and temperature field more stable in the cockpit.The corresponding results can provide necessary theoretical guidance for the further design of the cockpit structure.

关键词： Aircraft cockpit airflow distribution flow characteristics temperature characteristics inhomogeneous behaviors

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姿控发动机开机过程瞬态流动特性研究

Aerospace China 2022年第3期23卷 15-22页

作者： HUANG Jian Shanghai Institute of Space Propulsion Shanghai 201112 Shanghai Engineering Research Center of Space Engine Shanghai 201112

Liquid bipropellant attitude control rocket engines are widely used in satellites,manned spaceships,deep space probes and other spacecraft.The performance of an attitude control engine is directly related to the lifetime,control precision and safety of a spacecraft.The study of flow characteristics of an engine transient process is important to improve its performance.In this paper,the transient flow test of a transparent test piece was carried out during the starting process of the attitude control engine.Then the transient process of the test piece was simulated and compared with the test results to verify the rationality of the simulation model.Transient flow simulation was carried out for the starting process of the real engine injector.The results show that the filling of the outer ring of the oxidant circuit is slower than that of the central collecting cavity,and the filling of the second layer of the outer ring is slower than that of the first layer.The filling process in the fuel path starts from the cooling hole near the inlet side and the fuel flows out in the circumferential direction.Installation direction has little influence on engine starting flow process in the ground state.The filling time of the engine in its vacuum state is longer than that in the ground state,the filling time of oxidizer is 31%longer than that in ground state,and the filling time of fuel is 57%longer than that in ground state.

关键词： attitude control engine starting process transient flow characteristics