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Numerical investigation on aerodynamic performance of a bionic flapping wing

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Applied Mathematics and Mechanics(English Edition) 2019年第11期40卷 1625-1646页

作者： xinghua chang Laiping ZHANG Rong MA Nianhua WANG State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000Sichuan ProvinceChina Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000Sichuan ProvinceChina

This paper numerically studies the aerodynamic performance of a bird-like bionic flapping *** geometry and kinematics are designed based on a seagull wing,in which flapping,folding,swaying,and twisting are *** in-house unsteady flow solver based on hybrid moving *** adopted for unsteady flow *** focus on two main issues in this study,i.e.,the influence of the proportion of down-stroke and the effect of span-wise *** results show that the proportion of downstroke is closely related to the efficiency of the flapping *** preferable proportion is about 0.7 by using the present geometry and kinematic model,which is very close to the observed *** finding is that the drag and the power consumption can be greatly reduced by the proper span-wise *** cases with different reduced frequencies are simulated and compared with each *** numerical results show that the power consumption reduces by more than 20%,and the drag coefficient reduces by more than 60% through a proper twisting motion for both *** flow mechanism is mainly due to controlling of unsteady flow separation by adjusting the local effective angle of *** conclusions will be helpful for the high-performance micro air vehicle (MAV) design.

关键词： flapping wing bird-like flapping unsteady flow radial basis function (RBF) hybrid dynamic mesh span-wise twisting mechanism

A 3D hybrid grid generation technique and a multigrid/parallel algorithm based on anisotropic agglomeration approach

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Chinese Journal of Aeronautics 2013年第1期26卷 47-62页

作者： Zhang Laiping Zhao Zhong chang xinghua He Xin State Key Laboratory of Aerodynamics China Aerodynamics Research and Development Center

A hybrid grid generation technique and a multigrid/parallel algorithm are presented in this paper for turbulence flow simulations over three-dimensional （3D） complex geometries. The hybrid grid generation technique is based on an agglomeration method of anisotropic tetrahedrons. Firstly, the complex computational domain is covered by pure tetrahedral grids, in which anisotropic tetrahedrons are adopted to discrete the boundary layer and isotropic tetrahedrons in the outer field. Then, the anisotropic tetrahedrons in the boundary layer are agglomerated to generate prismatic grids. The agglomeration method can improve the grid quality in boundary layer and reduce the grid quantity to enhance the numerical accuracy and efficiency. In order to accelerate the convergence history, a multigrid/parallel algorithm is developed also based on anisotropic agglomeration approach. The numerical results demonstrate the excellent accelerating capability of this multigrid method.

关键词： Anisotropic agglomeration approach Hybrid mesh generation Multigrid method Parallel computation Complex geometry

An efficient large-scale mesh deformation method based on MPI/Open MP hybrid parallel radial basis function interpolation

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Chinese Journal of Aeronautics 2020年第5期33卷 1392-1404页

作者： Zhong ZHAO Rong MA Lei HE xinghua chang Laiping ZHANG State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China

An efficient MPI/OpenMP hybrid parallel Radial Basis Function (RBF) strategy for both continuous and discontinuous large-scale mesh deformation is proposed to reduce the computational cost and memory *** the conventional parallel methods in which all processors use the same surface displacement and implement the same operation,the present method employs different surface points sets and influence radius for each volume point movement,accompanied with efficient geometry searching *** deformed surface points,also called Control Points (CPs),are stored in each *** displacement of spatial points is interpolated by using only 20-50 nearest control points,and the local influence radius is set to 5-20 times the maximum displacement of control *** shorten the searching time for the nearest control point clouds,an Alternating Digital Tree (ADT) algorithm for 3D complex geometry is designed based on an iterative bisection ***,an MPI/OpenMP hybrid parallel approach is developed to reduce the memory cost in each High-Performance Computing (HPC) node for large-scale *** 3D cases,including the ONERA-M6 wing and a commercial transport airplane standard model with up to 2.5 billion hybrid elements,are used to test the present mesh deformation *** robustness and high parallel efficiency are demonstrated by a wing deflection case with a maximum bending angle of 450 and more than 80% parallel efficiency with 1024 MPI *** addition,the availability for both continuous and discontinuous surface deformation is verified by interpolating the projecting displacement with opposite directions surface points to the spatial points.

关键词： Mesh deformation Moving mesh generation MPI/Open MP hybrid parallel computing Parallel radial basis function interpolation Unstructured hybrid grid

An automatic isotropic/anisotropic hybrid grid generation technique for viscous flow simulations based on an artificial neural network

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Chinese Journal of Aeronautics 2022年第4期35卷 102-117页

作者： Peng LU Nianhua WANG xinghua chang Laiping ZHANG Yadong WU School of Information Engineering Southwest University of Science and TechnologyMianyang 621010China School of Intelligent Manufacturing Engineering Chongqing University of Arts and ScienceChongqing 402160China Stake Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China Unmanned Systems Research Center National Innovation Institute of Defense TechnologyBeijing 100071China School of Computer Science and Technology Sichuan University of Science&EngineeringYibin 644005China

Based on the author’s previous research, a novel hybrid grid generation technique is developed by introducing an Artificial Neural Network(ANN) approach for realistic viscous flow simulations. An initial hybrid grid over a typical geometry with anisotropic quadrilaterals in the boundary layer and isotropic triangles in the off-body region is generated by the classical mesh generation method to train two ANNs on how to predict the advancing direction of the new point and to control the grid size. After inputting the initial discretized fronts, the ANN-based Advancing Layer Method(ALM) is adopted to generate the anisotropic quadrilaterals in boundary layers. When the high aspect ratio of the anisotropic grid reaches a specified value, the ANN-based Advancing Front Method(AFM) is adopted to generate isotropic triangles in the off-body computational *** initial isotropic triangles are smoothed to further improve the grid quality. Three typical cases are tested and compared with experimental data to validate the effectiveness of grids generated by the ANN-based hybrid grid generation method. The experimental results show that the two ANNs can predict the advancing direction and the grid size very well, and improve the adaptability of the isotropic/anisotropic hybrid grid generation for viscous flow simulations.

关键词： Advancing front method Advancing layer method Anisotropic quadrilateral grid generation Artificial neural network Isotropic triangular grid generation Machine learning

A CFD-based numerical virtual flight simulator and its application in control law design of a maneuverable missile model

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Chinese Journal of Aeronautics 2019年第12期32卷 2577-2591页

作者： Laiping ZHANG xinghua chang Rong MA Zhong ZHAO Nianhua WANG State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China

A CFD-based Numerical Virtual Flight(NVF)simulator is presented,which integrates an unsteady flow solver on moving hybrid grids,a Rigid-Body Dynamics(RBD)solver and a module of the Flight Control System(FCS).A technique of dynamic hybrid grids is developed to control the active control surfaces with body morphing,with a technique of parallel unstructured dynamic overlapping grids generating proper moving grids over the deflecting control surfaces(*** afterbody rudders of a missile).For the flow/kinematic coupled problems,the 6 Degree-Of-Freedom(DOF)equations are solved by an explicit or implicit method coupled with the URANS CFD *** module of the control law is explicitly coupled into the NVF simulator and then improved by the simulation of the pitching maneuver process of a maneuverable missile model.A nonlinear dynamic inversion method is then implemented to design the control law for the pitching process of the maneuverable missile *** and analysis of the pitching maneuver process are carried out by the NVF simulator to improve the flight control *** control response performance is obtained by adjusting the gain factors and adding an integrator into the control loop.

关键词： Dynamic hybrid grid generation Flight control law Flow/kinematic coupling method Maneuverable missile pitching Nonlinear dynamic inversion Numerical virtual?ight

Plasma-processed homogeneous magnesium hydride/ carbon nanocomposites for highly stable lithium storage

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Nano Research 2018年第5期11卷 2724-2732页

作者： xinghua chang Xinyao Zheng Yanru Guo Jun Chen Jie Zheng Xingguo Li Beijing National Laboratory for Molecular Sciences (BNLMS) College of Chemistry and Molecular Engineering Peking University Beijing 100871 China Academy for Advanced and Interdisciplinary Studies Peking University Beijing 100871 China

Magnesium hydride （MgH2） is a high-capacity anode material for lithium ion batteries, which suffers from poor cycling stability. In this stud）~ we describe a thermal plasma-based approach to prepare homogeneous MgH2/C nanocomposites with very high cycling stability. In this process, magnesium evaporation is coupled with carbon generation from the plasma decomposition of acetylene, leading to a homogeneous Mg/C nanocomposite, which can be easily converted to MgH2/C by hydrogenation. The MgH2/C nanocomposite achieves a high reversible capacity of up to 620 mAh·g^-1 after 1,000 cycles with an ultralow decay rate of only 0.0036% per cycle, which represents a significantly improved performance compared to previous results.

关键词： magnesium hydride anode lithium-ion batteries thermal plasma nanocomposite

Ultrafine Sn nanocrystals in a hierarchically porous N-doped carbon for lithium ion batteries

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Nano Research 2017年第6期10卷 1950-1958页

作者： xinghua chang Teng Wang Zhiliang Liu Xinyao Zheng Jie Zheng Xingguo Li Beijing National Laboratory for Molecular Sciences (BNLMS) College of Chemistry and Molecular Engineering Peking University Beijing 100871 China Academy for Advanced Interdisciplinary Studies Peking University Beijing 100871 China

We report a simple method of preparing a high performance, Sn-based anode material for lithium ion batteries （LIBs）. Adding H2O2 to an aqueous solution containing Sn2＋ and aniline results in simultaneous polymerization of aniline and oxidation of Sn2＋ to SnO2, leading to a homogeneous composite of polyaniline and SnO2. Hydrogen thermal reduction of the above composite yields N-doped carbon with hierarchical porosity and homogeneously distributed, ultrafine Sn particles. The nanocomposite exhibits excellent performance as an anode material for lithium ion batteries, showing a high reversible specific capacity of 788 mAh·g^-1 at a current density of 100 mA·g^-1 after 300 cycles and very good stability up to 5,000 mA·g^-1. The simple preparation method combined with the good electro- chemical performance is highly promising to promote the application of Sn based anode materials.

关键词： Sn polyaniline nanocomposite lithium ion battery (LIB)

Ultrafine Sn_(4)P_(3)nanocrystals from chloride reduction on mechanically activated Na surface for sodium/lithium ion batteries

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Nano Research 2020年第11期13卷 3157-3164页

作者： Zhiliang Liu Xiangxi Wang Zhuoyan Wu Sungjin Yang Shaolei Yang Shunpeng Chen Xinteng Wu xinghua chang Piaoping Yang Jie Zheng Xingguo Li Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationCollege of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin150001China Beijing National Laboratory for Molecular Sciences(BNLMS) College of Chemistry and Molecular EngineeringPeking University5 Yiheyuan RoadBeijing100871China Comprehensive Energy Research Center Institute of Science and TechnologyChina Three Gorges CorporationBeijing100038China Key Laboratory for Mineral Materials and Application of Hunan Province School of Minerals Processing and BioengineeringCentral South UniversityChangsha410083China

Nanostructured metal phosphides are very attractive materials in energy storage and conversion,but their applications are severely limited by complicated preparation steps,harsh conditions and large excess of highly toxic phosphorus *** we develop a highly efficient one-step method to synthesize Sn_(4)P_(3)nanostructure based on simultaneous reduction of SnCl_(4)and PCl_(3)on mechanically activated Na surface and in situ *** low-toxic PCl3 displays a very high phosphorizing efficiency(100%).Furthermore,this simple method is powerful to control phosphide *** Sn_(4)P_(3)nanocrystals(<5 nm)supported on carbon sheets(Sn_(4)P_(3)/C)are obtained,which is due to the unique bottom-up surface-limited *** the anode material for sodium/lithium ion batteries(SIBs/LIBs),the Sn_(4)P_(3)/C shows profound sodiation/lithiation extents,good phase-conversion reversibility,excellent rate performance and long cycling stability,retaining high capacities of 420 mAh/g for SIBs and 760 mAh/g for LIBs even after 400 cycles at 1.0 A/*** simple and efficient preparation,low-toxic and high-efficiency phosphorus source and good control of nanosize,this method is very promising for low-cost and scalable preparation of high-performance Sn_(4)P_(3)anode.

关键词： metal phosphide chloride reduction ultrafine Sn_(4)P_(3)nanocrystals lithium-ion battery(LIB) sodium-ion battery(SIB) anode material

Surface group directed low-temperature synthesis and self-assembly of Al nanostructures for lithium storage

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Nano Research 2023年第1期16卷 1733-1739页

作者： Xianglong Kong Zhi Li Xudong Zhao Shunpeng Chen Zhuoyan Wu Fei He Piaoping Yang xinghua chang Xingguo Li Zhiliang Liu Jie Zheng College of Material Sciences and Chemical Engineering Harbin Engineering UniversityHarbin 150001China Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Comprehensive Energy Research Center Institute of Science and TechnologyChina Three Gorges CorporationBeijing 100038China Key Laboratory for Mineral Materials and Application of Hunan Province School of Minerals Processing and BioengineeringCentral South UniversityChangsha 410083China

Nanostructured aluminum recently delivers a variety of new applications of the earth-abundant Al resource due to the unique properties,but its controllable synthesis remains very challenging with harsh conditions and spontaneously flammable ***,a surface group directed method is developed to efficiently achieve low-temperature synthesis and selfassembly of zero-dimensional(0D)Al nanocrystals over one-dimensional(1D)carbon fibers(Al@CFs)through non-flammable AlCl3 reduction at 70°*** calculations unveil surface‒OLi groups of carbon fibers exert efficient binding effect to AlCl3,which guides intimate adsorption and in-situ self-assembly of the generated Al *** distinctive 0D-over-1D Al@CFs provides long 1D conductive networks for electron transfer,ultrafine 0D Al nanocrystals for fast lithiation and excellent buffering effect for volume change,thus exhibiting high structure stability and superior lithium storage *** work paves the way for mild and controllable synthesis of Al-based nanomaterials for new high-value applications.

关键词： Al nanostructure low-temperature synthesis self-assembly surface group lithium storage