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Influence of rolling friction on single spout fluidized bed simulation

Particuology 2012年第5期10卷 582-591页

作者： Christoph Goniva Christoph Kloss Niels G. Deen Johannes A.M.Kuipers Stefan Pirker Christian-Doppler Laboratory on Particulate flow Modelling Johannes Kepler UniversityLinz Austria DCS Computing GmbH Linz Austria Christian-Doppler Laboratory on Particulate flow Modelling Johannes Kepler UniversityLinz Austria department of Chemical Engineering and Chemistry Eindhoven University of TechnologyEindhovenThe Netherlands department of Chemical Engineering and Chemistry Eindhoven University of TechnologyEindhovenThe Netherlands Christian-Doppler Laboratory on Particulate flow Modelling Johannes Kepler UniversityLinzAustria Institute of Fluid Mechanics and Heat Transfer Johannes Kepler UniversityLinzAustria

In this paper we study the effect of rolling friction on the dynamics in a single spout fluidized bed using Discrete Element Method （DEM） coupled to Computational Fluid Dynamics （CFD）. In a first step we neglect rolling friction and show that the results delivered by the open source CFD-DEM framework applied in this study agree with previous simulations documented in literature. In a second step we include a rolling friction sub-model in order to investigate the effect of particle non-sphericity. The influence of particle-particle as well as particle-wall rolling friction on the flow in single spout fluidized bed is studied separately. Adequate rolling friction model parameters are obtained using first principle DEM simulations and data from literature. Finally, we demonstrate the importance of correct modelling of rolling friction for coupled CFD-DEM simulations of spout fluidized beds. We show that simulation results can be improved significantly when applying a rolling friction model, and that experimental data from literature obtained with Positron Emission Particle Trackin~ fPEPT） technique can be satisfactorily reoroduced.

关键词： CFD-DEMOpen sourceRolling frictionSpout fluidized bedNon-sphericity

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The influence of sub-grid scale motions on particle collision in homogeneous isotropic turbulence

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Acta Mechanica Sinica 2018年第1期34卷 22-36页

作者： Yan Xiong Jing Li Zhaohui Liu Chuguang Zheng State Key Laboratory of Coal combustion School of Energy and Power Engineering Huazhong University of Science and Technology

The absence of sub-grid scale(SGS) motions leads to severe errors in particle pair dynamics, which represents a great challenge to the large eddy simulation of particle-laden turbulent flow. In order to address this issue,data from direct numerical simulation(DNS) of homogenous isotropic turbulence coupled with Lagrangian particle tracking are used as a benchmark to evaluate the corresponding results of filtered DNS(FDNS). It is found that the filtering process in FDNS will lead to a non-monotonic variation of the particle collision statistics, including radial distribution function, radial relative velocity, and the collision kernel. The peak of radial distribution function shifts to the large-inertia region due to the lack of SGS motions, and the analysis of the local flowstructure characteristic variable at particle position indicates that the most effective interaction scale between particles and fluid eddies is increased in FDNS. Moreover,this scale shifting has an obvious effect on the odd-order moments of the probability density function of radial relative velocity, i.e. the skewness, which exhibits a strong correlation to the variance of radial distribution function in *** a whole, the radial distribution function, together with radial relative velocity, can compensate the SGS effects for the collision kernel in FDNS when the Stokes number based on the Kolmogorov time scale is greater than 3.0. However,it still leaves considerable errors for St< 3.0.

关键词： Particle-laden turbulence Homogenous isotropic turbulence Large eddy simulation Particle collisions

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flow CHARACTERISTICS OF WALLflow DIESEL PARTICULATE FILTER SYSTEM WITH REVERSE PULSE AIR REGENERATION

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Chinese Journal of Mechanical Engineering 2005年第3期18卷 439-441页

作者： Yao Chunde Shao Yuping Zhang Chunrun Zi XinYun Jiang Dahai Deng Chenglin State Key Laboratory of Engine combustion Tianjin University Tianjin 300072 China department of Automotive Engineering Military Traffic Institute Tianjin 300161 China

To simulate steady airflows inside of wall-flow diesel particulate filters （DPF） with different reverse blowing pipes collocation, a mathematical model of the flow in a DPF is established by an equivalent continuum approach. The experimental results agree well with the theoretical values calculated from the model. Simulation shows that the velocity and the pressure distribution of the filters in the regenerative process are key factors to the filter＇s regeneration. How to decrease the mal-distribution of the flow in the filter and how to achieve the better regenerative performance at the least cost of air consumption in the regenerative process are the ultimate goals of the study. Calculation and experiments show that the goals can be realized through adjusting the angle of two reverse blowing pipes and their relative location suitably.

关键词： Wall-flow filter Reverse pulse air regeneration flow characteristic Simulation

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Characterization and performance of Pt/SBA-15 for low-temperature SCR of NO by C_3H_6

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Journal of Environmental Sciences 2013年第5期25卷 1023-1033页

作者： Xinyong Liu Zhi Jiang Mingxia Chen Jianwei Shi Wenfeng Shangguan Yasutake Teraoka Research Center for combustion and Environmental Technology Shanghai Jiao Tong University department of Energy and Material Sciences Faculty of Engineering SciencesKyushu UniversityKasugaFukuoka 816-8580Japan

Pt supported on mesoporous silica SBA-15 was investigated as a catalyst for low temperature selective catalytic reduction（SCR） of NO by C 3 H 6 in the presence of excess *** prepared catalysts were characterized by means of XRD,BET surface area,TEM,NO-TPD,NO/C 3 H 6-TPO,NH 3-TPD,XPS and 27 Al MAS *** effects of Pt loading amount,O 2 /C 3 H 6 concentration,and incorporation of Al into SBA-15 have been *** was found that the removal efficiency increased significantly after Pt loading,but an optimal loading amount was *** particular,under an atmosphere of 150 ppm NO,150 ppm C 3 H 6,and 18 vol.% O 2,0.5% Pt/SBA-15 showed remarkably high catalytic performance giving 80.1% NOx reduction and 87.04% C 3 H 6 conversion simultaneously at 140°*** enhanced SCR activity of Pt/SBA-15 is associated with its outstanding oxidation activities of NO to NO 2 and C 3 H 6 to CO 2 in low temperature *** research results also suggested that higher concentration of O 2 and higher concentration of C 3 H 6 favored NO *** incorporation of Al into SBA-15 improved catalytic performance,which could be ascribed to the enhancement of catalyst surface acidity caused by tetrahedrally coordinated AlO ***,the catalysts could be easily reused and possessed good stability.

关键词： low-temperature selective catalytic reduction C 3 H 6 Pt/SBA-15

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Differentially weighted direct simulation Monte Carlo method for particle collision in gas-solid flows

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Particuology 2015年第4期13卷 135-145页

作者： Yongxiang He Haibo Zhao Haoming Wang Chuguang Zheng State Key Laboratory of Coal combustion Huazhong University of Science and Technology

In gas-solid flows, particle-particle interaction （typical, particle collision） is highly significant, despite the small particles fractional volume. Widely distributed polydisperse particle population is a typical characteristic during dynamic evolution of particles （e.g., agglomeration and fragmentation） in spite of their initial monodisperse particle distribution. The conventional direct simulation Monte Carlo （DSMC） method for particle collision tracks equally weighted simulation particles, which results in high statistical noise for particle fields if there are insufficient simulation particles in less-populated regions. In this study, a new differentially weighted DSMC （DW-DSMC） method for collisions of particles with different number weight is proposed within the framework of the general Eulerian-Lagrangian models for hydrodynamics. Three schemes （mass, momentum and energy conservation） were developed to restore the numbers of simulation particle while keeping total mass, momentum or energy of the whole system unchanged respectively. A limiting case of high-inertia particle flow was numerically simulated to validate the DW-DSMC method in terms of computational precision and efficiency. The momentum conservation scheme which leads to little fluctuation around the mass and energy of the whole system performed best. Improved resolution in particle fields and dynamic behavior could be attained simultaneously using DW-DSMC, compared with the equally weighted DSMC. Meanwhile, computational cost can be largely reduced in contrast with direct numerical simulation.

关键词： Direct simulation Monte Carlo Differentially weighted method Gas-solid flow Particle-particle collision Four-way coupling

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A review of engine application and fundamental study on turbulent premixed combustion of hydrogen enriched natural gas

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Science China(Technological Sciences) 2014年第3期57卷 445-451页

作者： WANG JinHua WEI ZhiLong ZHANG Meng HUANG ZuoHua State Key Laboratory of Multiphase flow in Power Engineering Xi'an Jiaotong University

The application and fundamental study on turbulent premixed combustion of hydrogen enriched natural gas is reviewed in this *** include the combustion characteristics of direct injection engine fueled with hydrogen enriched natural gas,visualization study of direct injection combustion of hydrogen enriched natural gas using a constant volume vessel,and the fundamental study of turbulent premixed combustion of hydrogen enriched natural *** effect of additional hydrogen on the combustion process of natural gas engine is investigated from the fundamental view of the interaction between combustion reaction and turbulent flow.

关键词： natural gas hydrogen direct injection combustion turbulent premixed combustion OH-PLIF engine

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An　Experimental　Study　on　the　Motion　of　Droplets　in　Flue　Gas　Humidification　Activator　with　Pulse　Laser　Sheet　Photography

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Journal of Thermal Science 1994年第2期3卷 142-146页

作者： Ke Jiang Xuchang Xu Xuegui Shi(State Key Laboratory of Efficient and Clean combustion of Coal, department of Thermal Engineering,Tsinghua University, Beijing 100084, China) State Key Laboratory of Efficient and Clean combustion of Coal Department of Thermal Engineering Tsinghua University Beijing China

In this paper a technique is introduced on visualization of emulsified droplets in gas stream by pulse laser sheet photography. By this technique fairly clear photographs of the concentration and velocity profiles of water droplets in an activation reactor were obtained. The results of the study show that with a venturi tube installed in the activator, the distribution of the droplets is more uniform than without it; the uniformity of the distribution of the droplets can improve the efficiency of the activation of the sorbent particles in the reactor. The picture of the collision of the droplets was obtained in the experiment, which could be used as basis for the study of the mechanism of humidified activation process. The results of the experimental study of the deposition of the droplets on the reactor walls is also described and discussed.

关键词： humidifier activator pulse laser sheet photography distribution of droplets deposition.

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Simultaneous multiple time scale imaging for kHz-MHz high-speed accelerometry

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Photonics Research 2022年第7期10卷 1712-1722页

作者： VASSILY KORNIENKO DAVID ANDERSSON MEHDI STITI JONAS RAVELID SIMON EK ANDREAS EHN EDOUARD BERROCAL ELIAS KRISTENSSON Division of combustion Physics Department of PhysicsLund UniversityLundSweden

Fast transient events,such as the disintegration of liquid bodies or chemical reactions between radical species,involve various processes that may occur at different time ***,there are two alternatives for monitoring such events:burst-or high-speed *** imaging at ultrahigh speeds(~100 MHz to THz)allows for the capture of nature's fastest processes but only for a narrowly confined period of time and at a repetition rate of~10 *** long lasting,rapidly evolving transient events requires a significantly higher repetition rate,which is met by existing~kHz to 1 MHz high-speed imaging ***,the use of such systems eliminates the possibility to observe dynamics occurring on the sub-microsecond time *** this paper,we present a solution to this technological gap by combining multiplexed imaging with high-speed sensor technology,resulting in temporally resolved,high-spatial-resolution image series at two simultaneous time *** further demonstrate how the collection of such data opens up the tracking of rapidly evolving structures up to MHz burst rates over long durations,allowing,for the first time,to our knowledge,the extraction of acceleration fields acting upon the liquid bodies of an atomizing spray in two dimensions at k Hz frame rates.

关键词： repetition high transient

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Numerical simulations of the discontinuous progression of cerebral aneurysms based on fluid-structure interactions study

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Science China(Physics,Mechanics & Astronomy) 2010年第5期53卷 944-953页

作者： MA XiaoQi1,WANG YueShe1,YU FangJun1 & WANG GuoXiang1,2 1 State Key Laboratory of Multiphase flow in Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China 2 department of Mechanical Engineering,The University of Akron,Akron,OH 44325-3903,USA State Key Laboratory of Multiphase flow in Power Engineering Xi’an Jiaotong University Xi’an China department of Mechanical Engineering The University of Akron Akron USA

Investigations into the characteristics of hemodynamics will provide a better understanding of the pathology of cerebral aneurysms for *** this work,a steady state discontinuous-growth model of the cerebral aneurysms was *** the assumption of the fluid-structure interaction between the wall of blood vessel and blood,a fluid-structure coupling numerical simulation for this model was built using software ANSYS and *** simulation results showed that as the aneurysm volume increased,a blood flow vortex came forth,the vortex region became asymptotically larger,and eddy density became gradually stronger in *** the emergence of the vortex region,the blood flow in the vicinity of the downstream in the aneurysms volume turned into bifurcated flow,and the location of the flow bifurcated point was shifted with the aneurysm volume growing while directions of the shear stress applied to two sides of the bifurcated point were *** Von Mises stress distribution along the wall of aneurysm volume decreased in the prior period and increased gradually in the later *** maximum stress was in the neck of the volume and the minimum was on the distal end in the whole process of *** was shown that as the aneurysm increased the maximum deformation location of the aneurysm,vertical to the streamline,was transferred from the distal end of the aneurysm to its neck,then back to its distal end of the aneurysm again.

关键词： cerebral aneurysm fluid-structure interaction wall shear stress discontinuous progression

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Two-dimensional phonon engineering triggers microscale thermal functionalities

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National Science Review 2019年第6期6卷 1071-1073页

作者： Run Hu Xiaobing Luo State Key Laboratory of Coal combustion School of Energy and Power Engineering Huazhong University of Science and Technology

Thermal metamaterials enable heat-flow manipulation alongside many emerg-ing thermal functionalities. However,macroscale experimental performancesare usually less satisfactory due to the errors of effective medium des... 详细信息

关键词： Two-dimensional phonon engineering triggers microscale thermal functionalities

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