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Numerical simulation of tetrahedral particle mixing and motion in rotating drums

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Particuology 2018年第4期16卷 1-11页

作者： Nan Gui Xingtuan Yang jiyuan tu Shengyao Jiang Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Aclvanced Nuclear Energy Technology Key Laboratory of Advancecl Reactor Engineering and Safety of Ministry of Education Tsinghua University Beijing 100084 China School of Engineering RMIT University Melbourne VIC 3083 Australia

A regular tetrahedron is the simplest three-dimensional structure and has the largest non-sphericity. Mixing of tetrahedral particles in a thin drum mixer was studied by the soft-sphere-imbedded pseudo- hard particle model and compared with that of spherical particles. The two particle types were simulated with different rotation speeds and drum filling levels. The Lacey mixing index and Shannon information entropy were used to explore the effects of sphericity on the mixing and motion of particles. Moreover, the probability density functions and mean values and variances of motion velocities, including translational and rotational, were computed to quantify the differences between the motion features of tetrahedra and spheres. We found that the flow regime depended on the particle shape in addition to the rotation speed and filling level of the drum. The mixing of tetrahedral particles was better than that of spherical particles in the rolling and cascading regimes at a high filling level, whereas it may be poorer when the filling level was low. The Shannon information entropy is better than the Lacey mixing index to evaluate mixing because it can reflect the real change of flow regime from the cataracting to the centrifugal regime, whereas the mixing index cannot.

关键词： Tetrahedron Non-spherical particle Mixing Drum Flow regime Discrete element method

Effects of volumetric fraction and included angle of composite particles on the discharge of binary mixtures in hoppers

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Particuology 2020年第4期18卷 80-90页

作者： Liange Ge Nan Gui Xingtuan Yang jiyuan tu Shengyao Jiang Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and SafetyMinistry of EducationTsinghua UniversityBeijing 100084China School of Engineering RMIT UniversityMelbourneVIC 3083Australia

The discharge behavior of particles is important in many industrial applications,such as in the core of a pebble bed reactor,which uses a hopper bed filled with many large *** this work,a mixture composed of two particle types,freely discharged from a pebble bed,is simulated using the discreteelement *** is a spherical pebble of diameter equal to that of the fuel pebble of the *** other is a composite particle comprising three spherical pebbles bonded *** included angleαof the three pebbles characterized the particle conformation,which may affect the discharge behavior of the *** effects of volume fraction of the multi-sphere x(equivalent to the number fraction)on the discharge are also *** patterns,number flow rate,discharge velocity,and mean force of the mixture are computed to help in revealing discharge *** results show that increasing eitherαor x reduces the discharge flow *** and correlations give a quantitative evaluation of the independent effects ofαand *** analysis of velocity and force explains the mechanism relevant to the main influencing factorsαand *** results are helpful in gaining a better understanding of the discharge feature of binary mixtures and in providing a quantitative evaluation of the discharge behavior of the reactor core,especially adverse failure conditions.

关键词： Pebble flow Particle flow Discharge flow Hopper bed Binary mixture Discrete element method

Discrete element-embedded finite element model for simulation of soft particle motion and deformation

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Particuology 2022年第9期20卷 88-100页

作者： Xu Liu Nan Gui Xiyuan Cui Xingtuan Yang jiyuan tu Shengyao Jiang Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and SafetyMinistry of EducationTsinghua UniversityBeijing 100084China School of Engineering RMIT UniversityMelbourneVIC 3083Australia

The motion and deformation of soft particles are commonly encountered and important in many appli-cations.A discrete element-embedded finite element model(DEFEM)is proposed to solve soft particle motion and deformation,which combines discrete element and finite element *** collisional surface of soft particles is covered by several dynamical embedded discrete elements(EDEs)to model the collisional external forces of the *** particle deformation,motion,and rotation are inde-pendent of each other in the *** deformation and internal forces are simulated using the finite element model,whereas the particle rotation and motion calculations are based on the discrete element *** inheriting the advantages of existing coupling methods,the contact force and contact search between soft particles are improved with the aid of the *** particle packing is simulated using the DEFEM for two cases:particle accumulation along a rectangular straight wall and a wall with an inclined *** large particle deformation in the lower layers can be simulated using current meth-ods,where the deformed particle shape is either irregular in the marginal region or nearly hexagonal in the tightly packed central *** method can also be used to simulate the deformation,motion,and heat transfer of non-spherical soft particles.

关键词： Discrete element method Finite element method Soft particle Collision Particle packing Pebble bed

Thermo-hydraulic experimental validation of an integrated modular small reactor operating in full power natural circulation

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Science China(Technological Sciences) 2014年第1期57卷 1-8页

作者： YANG Xingtuan REN Cheng LIU ZhiYong tu jiyuan JIANG ShengYao Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Institute of Nuclear and New Energy Technology Tsinghua University

Small reactors have become a new hotspot of international nuclear energy *** nuclear heating reactor(NHR)technology developed by Tsinghua University is an important multipurpose small reactor solution with features such as high integration,modular design and full power natural circulation.A new small reactor based on the existing NHR-200 reactor was developed by the Institute of Nuclear and New Energy Technology of Tsinghua University.A full-scale natural circulation test loop with the same operating parameters as the actual reactor was built in order to experimentally validate the natural circulation ability of the reactor primary loop and heat-transfer ability of fuel assemblies and heat *** results are given in detail,including parameter validation of the reactor primary loop,flow rules of the natural circulation and heat-transfer coefficients of heaters and heat exchangers,which can be directly used in the actual reactor as a reference for optimization ***,a characteristic parameter k is proposed to represent the natural circulation ability of a *** using the new data arrangement method in the form of parameter k,comprehensive experimental results of the natural circulation can be represented by a simple integrated *** work in this paper is of importance in broadening application fields and pushing forward commercialization of the NHR type reactors.

关键词： small reactor natural circulation validation experiment

Numerical investigation of turbulent bubbly wakes created by the ventilated partial cavity

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Science China(Physics,Mechanics & Astronomy) 2012年第2期55卷 297-304页

作者： XIANG Min ZHANG WeiHua CHEUNG S.C.P. tu jiyuan Institute of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China School of Aerospace Mechanical and Manufacturing EngineeringRMIT UniversityVictoria 3083Australia

This paper presents a numerical study on the turbulent bubbly wakes created by the ventilated partial cavity.A semi-empirical approach is introduced to model the discrete interface of the ventilated cavity and its complex gas leakage rate induced by the local turbulent shear *** on the Eulerian-Eulerian two-fluid modeling framework,a population balance approach based on MUltiple-SIze-Group (MUSIG) model is incorporated to simulate the size evolution of the sheared off microbubbles and its complex interactions with the two-phase flow structure in the wake *** predictions at various axial locations downstream of the test body were in satisfactory agreement with the experimental *** captured bubbly wake structure illustrates that the bubbles may disperse as a twin-vortex tube driven by gravity *** predicted Sauter mean bubble diameter has confirmed the dominance of the coleascense process in the axial *** the bubbles develop downstream,the coleascense and breakup rate gradually reach balance,resulting in the stable bubble diameter.A close examination of the flow structures,gas void fraction distributions and the bubble size evolution provides valuable insights into the complex physical phenomenon induced by ventilated cavity.

关键词： ventilated cavity population balance bubbly wake computational fluid dynamics

Voidage correction method for DEM study of 3D pebble flows in a bed of cycloidal base

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Particuology 2024年第10期93卷 30-40页

作者： Zirui Xia Minglei Shi Quan Zou Nan Gui Xingtuan Yang jiyuan tu Shengyao Jiang Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and SafetyMinistry of EducationTsinghua UniversityBeijing100084China Department of Engineering Physics Tsinghua UniversityBeijing100084China Department of Automation Tsinghua UniversityBeijing100084China School of Engineering RMIT UniversityMelbourneVIC3083Australia

Voidage(porosity or void fraction)in packed particles(or pebbles)is of fundamental importance in calculating the pressure drop,obtaining the drag,predicting the bed permeability,estimating the neutron streaming,*** the case when particles are deformed,a method of voidage correction during the packing state is proposed using a Discrete Element Method(DEM)simulation of 3D pebble flow inside a bed of cycloidal base.A function to evaluate the remaining volume of a pebble intercepted by horizontal and vertical planes is proposed for voidage *** that,the process of solving voidage distribution is provided in *** this method,the voidage inside the cycloidal-base pebble bed is obtained to refer to reported similar data for *** method can be potentially used for dynamical voidage calculation in CFD-DEM simulation which can get suitable voidage distribution after the correction.

关键词： Voidage Pebbleflow Packed bed Discreteelementmethod Cycloidal base KD-Tree Volume correction

Quality assessment of processed Eucommiae Cortex based on the color and tensile force

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Medicine in Novel Technology and Devices 2022年第4期16卷 162-171页

作者： Haiying Xu Lanqing Li Chunmei Tan Juanjuan Han Linghang Qu jiyuan tu Xianqiong Liu Kang Xu Hubei Engineering Technology Research Center of Chinese Materia Medica Processing College of PharmacyHubei University of Chinese MedicineWuhan430065China

Eucommiae Cortex(EC),the dried stem bark of Eucommia ulmoides Oliv,has been traditionally used to strengthen the muscle and bone tissues and improve liver and kidney functions in East Asian countries,including China,Japan,and ***-fried EC(SFEC)is made by using mixing EC and saline together based on the protocol of Chinese Materia Medica Processing(CMMP)for clinical ***,the clinical effectiveness of SFEC is directly impacted by the frying temperature and *** precise techniques for evaluating the caliber of SFEC have yet to be ***,this study aimed to establish a fast and accurate quality-check method for SFEC decoction *** to the frying temperature and time,four different categories of SFEC had been got according to the Chinese Pharmacopoeia method as Raw(R),Under(U),Moderately(M),and Overly(O).The red(R),green(G),blue(B),and light(L)color values of the decoction pieces were quantitated using the Photoshop software to determine the standard value range of the L color(raw[104.44±15.06],under[67.28±8.20],moderately[39.94±6.40],and over[15.02±5.03]).Additionally,the tensile strengths and pinoresinol diglucoside(PDG)levels of EC gum-silks were measured using the mechanical tensile test and HPLC,*** also conducted Pearson correlation analysis on the L color value,EC gum-silk tension(FbcN),and PDG level,and established the following muliple-linear regression equation:the decline in PDG level(w)=0.829-0.001×FbeN-0.009×*** conclusion,the L color value and FbeN could be used for cluster analysis of four categories of ***,based on the correlation among the L color value,gum-silk tensile test,and PDG level,a rapid and accurate quality-control method for SFEC decoction pieces with different frying temperatures and durations was *** method facilitates the manufacturing of efficacious SFEC.

关键词： Eucommia ulmoides Oliv Color recognition Tensile test Pattern recognition Content prediction

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90°弯管内气固两相流湍流变动实验研究

水动力学研究与进展（A辑） 2010年第4期25卷 559-565页

作者：张洪军赵周林 YANG William tu jiyuan 何春生中国计量学院流体检测与仿真研究所杭州310018 School of Aerospace Mechanical and Manufacturing Engineering RMIT University Vic. 3083 Australia Commonwealth Scientific and Industrial Research Organisation Clayton South Vic. 3169 Australia

采用相位多普勒测速仪(PDA)对方形截面90°弯管内稀相气固两相流动进行了测量。颗粒相采用平均粒径为77μm的玻璃球,气相测量采用雾化水滴为示踪粒子。实验雷诺数Re=105(平均速度U0=10m/s)。文中对单相气体流动和气粒流中气相流动进行... 详细信息

采用相位多普勒测速仪(PDA)对方形截面90°弯管内稀相气固两相流动进行了测量。颗粒相采用平均粒径为77μm的玻璃球,气相测量采用雾化水滴为示踪粒子。实验雷诺数Re=105(平均速度U0=10m/s)。文中对单相气体流动和气粒流中气相流动进行了分析。其中,两相流动中气相流动数据是在PDA激光散射信号后处理过程中根据颗粒尺寸进行大小颗粒(小颗粒代表气相,大颗粒代表颗粒相)分离得到的。结果发现,平均流速方面气粒流动中的气相速度较单相气体流动低,此现象产生的原因,主要是由于颗粒对连续气相介质的拖拽作用;对于湍流脉动,两相流中气相的湍流脉动比单相气体流动大,这主要是因为动能较大的颗粒相把动能传递给了气相,而这些颗粒的动能主要来源于壁面或颗粒间的碰撞。

关键词：相位多普勒测速仪PDA 90°弯管稀相气固两相流湍流变动

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纳米流体沸腾模型中某些物理参数的理论探讨

清华大学学报（自然科学版） 2015年第7期55卷 815-820页

作者：袁杨李祥东屠基元清华大学核能与新能源技术研究院先进反应堆工程与安全教育部重点实验室中国北京100084 墨尔本皇家理工大学航空与机械工程学院澳大利亚维多利亚3083

纳米流体核态沸腾理论预测模型的缺乏阻碍了其作为高效换热介质在工业系统中的应用。为实现对纳米流体核态沸腾的准确预测和计算,该文在现有实验基础上对纳米流体核态沸腾的特有现象进行了机理分析,建立了一系列的封闭方程来修正和完善... 详细信息

纳米流体核态沸腾理论预测模型的缺乏阻碍了其作为高效换热介质在工业系统中的应用。为实现对纳米流体核态沸腾的准确预测和计算,该文在现有实验基础上对纳米流体核态沸腾的特有现象进行了机理分析,建立了一系列的封闭方程来修正和完善经典的壁面热通量拆分模型,将模拟结果与纳米流体及纯工质核态沸腾的实验数据进行了对比,对模型中的一些物理参数进行了理论探讨。研究表明:采用壁面热通量拆分模型模拟纳米流体核态沸腾的关键在于准确模拟纳米包覆层对汽泡成核、生长及脱离规律的影响,特别是要准确把握壁面润湿性及壁面形态变化对核态沸腾特征的影响。

关键词：传热学纳米流体核态沸腾热通量拆分模型参数