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Numerical study and acceleration of LBM-RANS simulation of turbulent flow

Chinese Journal of Chemical Engineering 2018年第1期26卷 31-42页

作者： Shuli Shu ning yang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences

The coupled models of LBM （Lattice Boltzmann Method） and RANS （Reynolds-Averaged Navier-Stokes） are more practical for the transient simulation of mixing processes at large spatial and temporal scales such as crude oil mixing in large-diameter storage tanks. To keep the efficiency of parallel computation of LBM, the RANS model should also be explicitly solved; whereas to keep the numerical stability the implicit method should be better for PANS model. This article explores the numerical stability of explicit methods in 2D cases on one hand, and on the other hand how to accelerate the computation of the coupled model of LBM and an implicitly solved RANS model in 3D cases. To ensure the numerical stability and meanwhile avoid the use of empirical artificial lim- itations on turbulent quantities in 2D cases, we investigated the impacts of collision models in LBM （LBGK, MRT） and the numerical schemes for convection terms （WENO, TVD） and production terms （FDM, NEQM） in an explic- itly solved standard k-e model. The combination of MRT and TVD or MRT and NEQM can be screened out for the 2D simulation of backward-facing step flow even at Re = 107. This scheme combination, however, may still not guarantee the numerical stability in 3D cases and hence much finer grids are required, which is not suitable for the simulation of industrial-scale *** we proposed a new method to accelerate the coupled model of LBM with RANS （implicitly solved）. When implemented on multiple GPUs, this new method can achieve 13.5-fold accelera- tion relative to the original coupled model and 40-fold acceleration compared to the traditional CFD simulation based on Finite Volume （FV） method accelerated by multiple CPUs. This study provides the basis for the transient flow simulation of larger spatial and temporal scales in industrial applications with LBM-RANS methods.

关键词： Lattice Boltzmann Method Reynolds-Averaged Navier-Stokes Graphic Processing Units mixing transient simulation

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Modeling of co-current and counter-current bubble columns with an extended EMMS approach

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Particuology 2019年第3期17卷 126-135页

作者： Xiaoping Guan ning yang State Key Laboratory of Multi-phase Complex System Institute of Process Engineering Chinese Academy of Sciences P.O. Box 353 Beijing 100190 China

Bubble columns can be operated in semi-batch, co-current or counter-current mode. This study attempts to extend the dual-bubble-size (DBS) model, viz., the energy-minimization multi-scale (EMMS) model for gas-liquid systems, to co-current and counter-current bubble columns. With the increase of superficial liquid velocity, the predicted total gas holdup and regime transition are in accordance with experiments. A DBS drag model was then developed and incorporated into the CFD simulation. The total gas holdup and local gas holdup radial distribution in both the co-current and counter-current bubble columns are well estimated. The findings in the present work demonstrate that developing closure laws through the stability condition is of great significance in modeling complicated multi-scale flow in bubble columns.

关键词： Co-current Counter-current Bubble columns CFD Drag model

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Computational fluid dynamics simulation of hydrodynamics in the riser of an external loop airlift reactor

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Particuology 2016年第4期14卷 95-101页

作者： Xuedong Jiang ning yang Bolun yang Department of Chemical Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Center for Mesoscience and State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China

Local hydrodynamics in the riser of an external loop airlift reactor （EL-ALR） are identified and the performances of three drag models are evaluated in computational fluid dynamics simulation. The simulation results show that the Schiller-Naumann drag model underestimated the local gas holdup at lower superficial gas velocity whereas the Tomiyama drag model overestimated that at higher superficial gas velocity. By contrast, the dual-bubble-size （DBS）-local drag model gave more reasonable radial and axial distri-butions of gas holdup in all cases. The reason is that the DBS-local drag model gave correct values of the lumped parameter, i,e., the ratio of the drag coefficient to bubble diameter, for varying operating conditions and radial positions. This ratio is reasonably expected to decrease with increasing superficial gas velocity and be smaller in the center and larger near the wall. Only the DBS-local drag model correctly reproduced these trends. The radial profiles of the axial velocity of the liquid and gas predicted by the DBS-local model also agreed well with experimental data.

关键词： Computational fluid dynamics External loop airlift reactor Drag model Gas holdup Mnltiscale Mesoscale

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Characteristic-knowledge-aided spectral detection of high frequency first-order sea echo

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Journal of Systems Engineering and Electronics 2009年第4期20卷 718-725页

作者： Li yang Zhang ning yang Qiang Inst. of Electronic Engineering Harbin Inst. of Technology Harbin 150001 P. R. China

To detect high frequency （HF） first-order sea echo spectra contaminated with ships, ionosphere interference, and other, a new characteristic-knowledge-aided detection method is proposed. With 2-D image features in range-Doppler spectrum, the trend of first-order sea echoes is extracted as indicative information by a multi-scale filter. Detection rules for both single and splitting first-order sea echoes are given based on the characteristic knowledge combining the indicative information with the global characteristics such as amplitude, symmetry, continuity, etc. Compared with the classical algorithms, the proposed method can detect and locate the first-order sea echo in the HF band more accurately especially in the environment with targets/clutters smearing. Experiments with real data verify the validity of the algorithm.

关键词： spectral detection first-order sea echo characteristic knowledge aided HF surface wave radar Bragg peak splitting.

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Structural Nonlinear Flutter Characteristics Analysis for an Actuator-fin System with Dynamic Stiffness

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Chinese Journal of Aeronautics 2011年第5期24卷 590-599页

作者： yang ning WU Zhigang yang Chao School of Aeronautic Science and Engineering Beihang University Beijing 100191 China

The flutter characteristics of an actuator-fin system are investigated with structural nonlinearity and dynamic stiffness of the electric motor. The component mode substitution method is used to establish the nonlinear governing equations in time domain and frequency domain based on the fundamental dynamic equations of the electric motor and decelerator. The existing describing function method and a proposed iterative method are used to obtain the flutter characteristics containing preload freeplay nonlinearity when the control command is zero. A comparison between the results of frequency domain and those of time domain is studied. Simulations are carried out when the control command is not zero and further analysis is conducted when the freeplay angle is changed. The results show that structural nonlinearity and dynamic stiffness have a significant influence on the flutter characteristics. Limit cycle oscillations （LCOs） are observed within linear flutter boundary. The response of the actuator-fin system is related to the initial disturbance. In the nonlinear condition, the amplitude of the control command has an influence on the flutter characteristics.

关键词： aeroelasticity flutter actuators dynamic stiffness structural nonlinearity component mode substitution method describing functions

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驱控一体的旋拧式果实采摘执行器设计与试验

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农机化研究 2025年第3期47卷 48-55页

作者：严童杰冯青春郭鑫杨宁江苏大学电气信息工程学院江苏镇江212000 北京市农林科学院智能装备技术研究中心北京100097 国家农业智能装备工程技术研究中心北京100097 农业智能装备技术北京市重点实验室北京100097

针对果园智能化采收作业需要,设计了支持总线扩展的驱控一体旋拧采摘末端执行器,旨在为多臂并行采摘机器人研发提供支撑。在对标准苹果树果实物理形态统计分析基础上,结合人工采摘方法,提出了“吸附-夹持-旋拧”的采摘机械操作方法,并... 详细信息

针对果园智能化采收作业需要,设计了支持总线扩展的驱控一体旋拧采摘末端执行器,旨在为多臂并行采摘机器人研发提供支撑。在对标准苹果树果实物理形态统计分析基础上,结合人工采摘方法,提出了“吸附-夹持-旋拧”的采摘机械操作方法,并设计了基于双舵机驱动的紧凑型采摘执行机构,对其吸盘、夹持和旋拧电机的关键参数进行了优化设计。面向多执行并行采摘需要,设计了基于CANopen通讯的采摘操作驱动器,实现了多执行器的总线扩展。通过现场试验对执行器作业性能进行了测试,结果表明:果实大小在60~100 mm之间,采摘成功率可达到90%,吸盘最优停留时间为1.00 s,吸盘最优接近距离为1.0 mm,最优旋拧角度为360°。

关键词：采摘机器人驱控一体旋拧采摘 CANopen

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Exploration on the stability conditions in bubble columns by noncooperative game theory

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Chinese Journal of Chemical Engineering 2022年第10期50卷 75-84页

作者： Jiachen Liu Xiaoping Guan ning yang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

The energy-minimization multiscale(EMMS)model,originally proposed for gas-solid fluidization,features a stability condition to close the simplified conservation *** was put forward to physically reflect the compromise of two dominant mechanisms,i.e.,the particle-dominated with minimal potential energy of particles,and the gas-dominated with the least resistance for gas to penetrate through the particle *** stability condition was then formulated as the minimization of the ratio of these two physical ***,the EMMS approach was later extended to the gas-liquid flow in bubble columns,termed dual-bubble-size *** considers the compromise of two dominant mechanisms,i.e.,the liquid-dominated regime with small bubbles,and the gas-dominated regime with large *** stability condition was then formulated as the minimization of the sum of these two physical ***,the two stability conditions were expressed in different manner,though gas-solid and gas-liquid systems bear some *** addition,both the conditions transform the original multiobjective variational problem into a single-objective *** mathematical formulation of stability condition remains therefore an open *** study utilizes noncooperative game theory and noninferior solutions to directly solve the multi-objective variational problem,aiming to explo re the different pathways of compromise of dominant *** results show that only keeping the single dominant mechanism cannot capture the jump change of gas holdup,which is associated with flow regime *** of dominant mechanisms,noninferior solutions and noncooperative game theory can predict the flow regime ***,the game between the two mechanisms makes the two-bubble structure degenerate and reduce to the single-bubble *** game of the three mechanisms restores the two-bubble *** exploration on the formulation of stability conditions may

关键词： Bubble column Flow regimes Mesoscale Noncooperative gametheory

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Identification of nonlinear multi-degree-of freedom structures based on Hilbert transformation

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1725-1736页

作者： WU ZhiGang yang ning yang Chao School of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics

The modeling method and identified method adapted to multi-degree-of-freedom structures with strucrural nonlinearities are *** component mode synthesis method is used to establish the nonlinear governing equations by extending the connected *** on the modeling method,the Hilbert transform method is applied to identify the nonlinear stiffness of multi-degree-of-freedom *** analysis and identification of a typical folding wing configuration with three freeplay hinges are *** nonlinear governing equation is established based on present methods and the computing results of different stiffness are checked by finite element *** order to illustrate the influence of the nonlinearities,the frequency response characteristics of the structure are analyzed and Hilbert transform is *** Hilbert transform identification method is utilized to identify the nonlinear stiffness of nonlinear hinges in the time domain and several parametric studies are *** addition,the comparison of response is made to illustrate the feasibility of the *** results show that the extending component mode synthesis method in the present work can be used to establish the governing equation with structural *** on the modeling method,the Hilbert transform identified method can be extended to multi-degree-of-freedom structures accurately.

关键词： structural nonlinearity identification Hilbert transformation component mode synthesis method dynamic analysis dynamic response

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Facile Synthesis of Functional Poly (ε-caprolactone) via Janus Polymerization

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Chinese Journal of Polymer Science 2019年第9期37卷 858-865页

作者： Huan Qiu Zhe-ning yang Jun Ling Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Functionalized aliphatic polyesters attract increasing attentions as biocompatible and biodegradable polymers with broad applications in biological science. In this contribution, we propose a facile and controllable synthetic technique for functional poly(ε-caprolactone)(PCL) via Janus polymerization, which comprises cationic ring-opening copolymerization (ROP) of ε-caprolactone (CL) with 3,3-bis(chloromethyl)oxacyclobutane (CO) and (coordinated) anionic ROP of CL at a single propagating chain by rare earth metal triflates (RE(OTf)3)and propylene oxide, thus generating block copolymers in one step. The compositions of the copolymers of poly(CLb-(CL-r-CO)) can be modulated by various RE(OTf)3. Scandium triflate catalyzes Janus polymerization to yield the copolymers containing the highest CO contents among all the RE(OTf)3 catalysts used with complete conversion of CL. The chlorine in CO repeating units is ready to be transferred into azide group which affords the modification sites to react with 9-ethynyl-9-fluorenol and mPEG-alkyne, respectively, via copper(I)-catalyzed azide-alkyne cycloaddition reaction with quantitative conversions of azides, as confirmed by FTIR analyses. According to NMR and SEC analyses, copolymers (PCC-g-PEG) bearing a homo-PCL block and a PEG-grafted block of poly(CO-co-CL) demonstrate well-defined chemical structures. The investigations on thermal properties reveal the strong phase separation between PCL and PEG blocks. The amphiphilic PCC-g-PEG is able to sei住assemble into micelles in aqueous solution while cylindrical and lamellar morphologies are observed in bulk. We provide an efficient protocol to synthesize functional PCL combining onestep Janus polymerization and precise post-polymerization click reaction.

关键词： Janus polymerization Functional poly(ε-caprolactone) Poly(3,3-bis(chloromethyl)oxacyclobutane) Ring-opening polymerization Rare earth metal catalysts

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Trimethyl phosphate-enhanced polyvinyl carbonate polymer electrolyte with improved interfacial stability for solid-state lithium battery

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Rare Metals 2022年第6期41卷 1889-1898页

作者： Fei Zheng Hao-Tong Li Yan-Zhen Zheng Dan Wang ning-ning yang Hai-yang Ding Xia Tao Beijing Key Laboratory of Green Recovery and Extractionof Rare and Precious Metals University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China General Research Institute of Nonferrous Metals Beijing 100088China China Automotive Battery Research Institute Co. Ltd.Beijing 101407China

The polyvinyl carbonate(PVC)polymer solid electrolyte can be in-situ generated in the assembled lithium-ion battery(LIBs);however,its rigid characteristic leads to uneven interface contact between electrolyte and *** this work,trimethyl phosphate(TMP)is introduced into the precursor solution for in-situ generation of flexible PVC solid electrolyte to improve the interfacial contact of elec-trolyte and electrodes together with ionic *** PVC-TMP electrolyte exhibits good interface compatibility with the lithium metal anode,and the lithium symmetric battery based on PVC-TMP electrolyte shows no obvious polarization within 1000 h *** a consequence,the initial interfacial resistance of battery greatly decreases from 278Ω(LiFePO_(4)(LFP)/PVC/Li)to 93Ω(LFP/PVC-TMP/Li)at 50℃,leading to an improved cycling stability of the LFP/PVC-TMP/Li *** in-situ preparation of solid electrolyte within the battery is demonstrated to be very significant for commercial application.

关键词： Trimethyl phosphate Solid polymer electrolyte Interface stability Compatibility Lithium ion battery

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