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Large eddy simulation of unconfined turbulent swirling flow

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Science China(Technological Sciences) 2015年第10期58卷 1731-1744页

作者： zhang hongda HAN Chao YE TaoHong zhang JiMin CHEN YiLiang Department of Thermal Science and Energy Engineering University of Science and Technology of China

Large eddy simulations(LES) were performed to study the non-reacting flow fields of a Cambridge swirl burner. The dynamic Smagorinsky eddy viscosity model is used as the sub-grid scale turbulence model. Comparisons of experimental data show that the LES results are capable of predicting mean and root-mean-square velocity profiles. The LES results show that the annular swirling flow has a minor impact on the formation of the bluff-body recirculation zone. The vortex structures near the shear layers, visualized by the iso-surface of Q-criterion, display ring structures in non-swirling flow and helical structures in swirling flow near the burner exit. Spectral analysis was employed to predict the occurrence of flow oscillations induced by vortex shedding and precessing vortex core(PVC). In order to extract accurately the unsteady large-scale structures in swirling flow, a three-dimensional proper orthogonal decomposition(POD) method was developed to reconstruct turbulent fluctuating velocity fields. POD analysis reveals that flow fields contain co-existing helical and toroidal shaped coherent structures. The helical structure associated with the PVC is the most energetic dynamic flow structure. The latter toroidal structure associated with vortex shedding has lower energy content which indicates that it is a secondary structure.

关键词： Cambridge swirl burner large eddy simulation proper orthogonal decomposition vortex shedding and breakdown,precessing vortex core

Large eddy simulation of turbulent premixed piloted flame using artificial thickened flame model coupled with tabulated chemistry

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Applied Mathematics and Mechanics(English Edition) 2018年第9期39卷 1277-1294页

作者： Zhou YU hongda zhang Taohong YE Minming ZHU Department of Thermal Science and Energy Engineering University of Science and Technology of China Shenyang Engine Research Institute Aero Engine (Group) Corporation of China

A sub-grid scale(SGS) combustion model, which combines the artificial thickened flame(ATF) model with the flamelet generated manifold(FGM) tabulation method, is proposed. Based on the analysis of laminar flame structures, two self-contained flame sensors are used to track the diffusion and reaction processes with different spatial scales in the flame front, respectively. The dynamic formulation for the proposed SGS combustion model is also performed. Large eddy simulations(LESs) of Bunsen flame F3 are used to evaluate the different SGS combustion models. The results show that the proposed SGS model has the ability in predicting the distributions of temperature and velocity reasonably, while the predictions for the distributions of some species need further improvement. The snapshots of instantaneous normalized progress variables reveal that the flame is more remarkably and severely wrinkled at the flame tip for flame *** satisfactory results obtained by the dynamic model indicate that it can preserve the premixed flame propagation characteristics better.

关键词： large eddy simulation(LES) artificial thickened flame model tabulation dynamic modeling flame sensor

Large eddy simulation of turbulent premixed and stratified combustion using flame surface density model coupled with tabulation method

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Applied Mathematics and Mechanics(English Edition) 2018年第12期39卷 1719-1736页

Large eddy simulations(LESs) are performed to investigate the Cambridge premixed and stratified flames, SwB1 and SwB5, respectively. The flame surface density(FSD) model incorporated with two different wrinkling factor models, i.e., the Muppala and Charlette2 wrinkling factor models, is used to describe combustion/turbulence interaction, and the flamelet generated manifolds(FGM) method is employed to determine major scalars. This coupled sub-grid scale(SGS) combustion model is named as the FSD-FGM model. The FGM method can provide the detailed species in the flame which cannot be obtained from the origin FSD model. The LES results show that the FSD-FGM model has the ability of describing flame propagation, especially for stratified flames. The Charlette2 wrinkling factor model performs better than the Muppala wrinkling factor model in predicting the flame surface area change by the *** combustion characteristics are analyzed in detail by the flame index and probability distributions of the equivalence ratio and the orientation angle, which confirms that for the investigated stratified flame, the dominant combustion modes in the upstream and downstream regions are the premixed mode and the back-supported mode, respectively.

关键词： large eddy simulation(LES) flame surface density(FSD) model tabulation premixed combustion stratified combustion

A novel method for chemistry tabulation of strained premixed/stratified flames based on principal component analysis

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Applied Mathematics and Mechanics(English Edition) 2018年第6期39卷 855-866页

作者： Peng TANG hongda zhang Taohong YE Zhou YU Zhaoyang XIA Department of Thermal Science and Energy Engineering University of Science and Technology of China School of Mechatronics Engineering Chizhou University Shenyang Engine Research Institute Aero Engine(Group) Corporation of China

The principal component analysis （PCA） is used to analyze the high dimen- sional chemistry data of laminar premixed/stratified flames under strain effects. The first few principal components （PCs） with larger contribution ratios axe chosen as the tabu- lated scalars to build the look-up chemistry table. Prior tests show that strained premixed flame structure can be well reconstructed. To highlight the physical meanings of the tabu- lated scalars in stratified flames, a modified PCA method is developed, where the mixture fraction is used to replace one of the PCs with the highest correlation coefficient. The other two tabulated scalars are then modified with the Schmidt orthogonalization. The modified tabulated scalars not only have clear physical meanings, but also contain passive scalars. The PCA method has good commonality, and can be extended for building the thermo-chemistry table including strain rate effects when different fuels are used.

关键词： premixed flame stratified flame strain rate principal component analysis(PCA) chemistry table

Effect of polytetrafluoroethylene(PTFE) in current collecting layer on the performance of zinc-air battery

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Progress in Natural Science:Materials International 2020年第6期30卷 861-867页

作者： Bing Liu Yunkun Dai Lin Li hongda zhang Lei Zhao Fanrong Kong Xulei Sui Zhenbo Wang MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage State Key Lab of Urban Water Resource and Environment School of Chemistry and Chemical Engineering Harbin Institute of Technology State Grid Heilongjiang Electric Power Co. Ltd. Electric Power Research Institute

Beyond reasonable designing catalysts, the optimization of preparing air cathode has far-reaching implications for the development of Zinc-air batteries. In this study, the effect of Polytetrafluoroethylene(PTFE) in current collecting layer on the performance of Zinc-air battery was investigated. The results showed that as the polytetrafluoroethylene(PTFE) content and heat treatment temperature changed, the hydrophobicity and porosity of current collecting layer also changed, thereby affecting the performance of air cathode. The air cathode assembled with PTFE-3-300 possessed an excellent electrochemical performance, which was prepared by brushing PTFE and acetylene black(wherein the mass ratio of them is 18:5) on current collecting layer and then heating at300 °C. The obtained air cathode displayed relatively small polarization loss and excellent rate performance,showing a polarization potential of-0.405 V vs. Hg/Hg O at 100 m A cm-2and the voltage retention of 94.47%from 5 to 20 m A cm-2. Besides, the air cathode displayed excellent discharge stability maintaining average potential 1.3249 V for 100 h. Based on this work, a detailed understanding of the relationship of PTFE and current collecting layer can be achieved to improve the electrode design, architecture and fabrication.

关键词： PTFE content Temperature Zinc-air batteries Current collecting layer

A Possible Mechanism of High-Speed and Long-Distance Rockslides

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Journal of Earth Science 2024年第6期35卷 2158-2162页

作者： Yan Du hongda zhang Mowen Xie Yujing Jiang Santos D.Chicas Jingnan Liu School of Civil and Resource Engineering University of Science and Technology BeijingBeijing100083China Graduate School of Engineering Nagasaki UniversityNagasaki852-8521Japan Department of Agro-environmental Science Faculty of AgricultureKyushu UniversityFukuoka819-0395Japan

An important unsolved problem in engineering geology is the mechanism of high-speed and long-distance rockslides(HSLDR)in high-risk area,which deprive of many people's lives every *** bridge damage and its strength lo... 详细信息

关键词： rock geology damage

Genetic Differentiation and Conservation of 14 Surviving Individuals of Euryodendron excelsum Endemic to China

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Frontiers in Biology 2006年第1期1卷 23-28页

作者： Wang Ting Su Yingjuan Ye Huagu Ouyang Puyue Jiang Yu Sun Yufei Chen Guopei Deng Feng zhang hongda School of Life Sciences Sun Yat-sen UniversityGuangzhou 510275China Wuhan Botanical Garden Chinese Academy of SciencesWuhan 430074China South China Botanical Garden Chinese Academy of SciencesGuangzhou 510650China

Random amplification polymorphicDNA(RAPD)markers were used to assess the genetic variations and the evolutionary relationships among all 14 individuals of a critically endangered Euryodendron excelsum(Theaceae)population distributed in Ba Jia Zhen,Yangchun,Guangdong,***-three random primers detected 156 sites,out of which 95(60.26%)were polymorphic *** number of the observed alleles was 1.6090,and the number of the effective alleles was ***’s gene diversity was 0.1993,and Shannon index was 0.1534.A relatively high level of genetic variation was identified in *** unweighted pair group method with arithmetic mean(UPGMA)tree established from Jaccard similarity coefficients suggested that 14 individuals were clustered into two subgroups and that the No.2 plant was genetically distant from the rest of the *** UPGMA clustering was also supported by a principle components analysis of RAPD phenotypic *** management and conservation strategy of *** was proposed based on our results.

关键词： Euryodendron excelsum population genetic variation RAPD markers conservation management

Study of Plasma MHD Equilibrium in HL-2A Tokamak

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Southwestern Institute of Physics Annual Report

Southwestern Institute of Physics Annual Report 2006年第1期 123-125页

作者： HE hongda zhang Jinhua DONG Jiaqi LI Qiang

1 Introduction In an axisymmetric toroidal system, the MHD equilibrium G-S equation can be written as：

关键词：等离子体 MHD 环流器二号A装置核技术

软弱地层辅助坑道进隧道正洞上联洞+门架法挑顶施工技术

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隧道建设（中英文） 2021年第12期41卷 2150-2156页

作者：张洪达中铁隧道集团一处有限公司重庆401123

为提高软弱地层中辅助坑道进隧道正洞挑顶施工的安全性,有效控制应力集中部位的初期支护变形,解决传统挑顶工法中交叉口部位工序错综复杂、应力转换频繁的问题,以渝昆高铁昭通隧道2号斜井进正洞施工为依托,在充分分析斜井段膨胀土地质... 详细信息

为提高软弱地层中辅助坑道进隧道正洞挑顶施工的安全性,有效控制应力集中部位的初期支护变形,解决传统挑顶工法中交叉口部位工序错综复杂、应力转换频繁的问题,以渝昆高铁昭通隧道2号斜井进正洞施工为依托,在充分分析斜井段膨胀土地质特征的基础上,开展上联洞+门架法挑顶施工技术研究。通过在辅助坑道与正洞交叉口后方设置独立式上联洞掘进至正洞拱顶,多工作面同步实施正洞挑顶和斜井衬砌,结合密排门架法挑顶工艺,可以更好地拟合正洞开挖轮廓,实现安全、快速的挑顶作业。上联洞+门架法挑顶技术可以很好地解决辅助坑道交叉口段衬砌与正洞挑顶的施工干扰问题,实现2项作业的同步平行施工,加快挑顶施工进度,并通过工法革新有效规避了多种安全风险因素的叠加。

关键词：软弱地层辅助坑道隧道交叉口上联洞门架导洞法挑顶施工