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Comparative study of reduced-order modeling method for the cavitating flow over a hydrofoil

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Journal of Hydrodynamics 2023年第4期35卷 679-699页

作者： Yan-zhao Wu Ran Tao Di Zhu Ruo-fu Xiao College of Water Resources and Civil Engineering China Agricultural UniversityBeijing100083China Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System China Agricultural UniversityBeijing100083China College of Engineering China Agricultural UniversityBeijing100083China

As a high-dimensional complex nonlinear dynamic system,the analysis of the essence of flow has always been a difficult problem,especially in the flow including phase *** recent years,it has become a feasible method to reduce the dimension of flow structure by reduced-order modeling(ROM)*** this paper,through the cavitation numerical simulation of NACA0015 hydrofoil,two ROM methods are used to reduce and restore three different cavitation respectively-proper orthogonal decomposition(POD)and dynamic mode decomposition(DMD).The applicability of two methods in cavitation is discussed and reasons are *** results show that for stable cavitation,POD,DMD methods can accurately restore the flow field of a few modes with high *** unstable cavitation,only POD method can restore real flow field *** situation is mainly due to the fact that POD,DMD method are applicable to different energy ratios,and different main mode selection criterion of DMD will lead to different main *** can greatly simplify the complexity of *** a reasonable ROM can improve the accuracy of a small amount of database,and provide a basis for intelligent prediction of flow analysis.

关键词： Hydrofoil cavitation reduced-order model proper orthogonal decomposition dynamic mode decomposition

Vertical α-FeOOH nanowires grown on the carbon fiber paper as a free-standing electrode for sensitive H2O2 detection

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Nano Research 2016年第8期9卷 2260-2269页

作者： Shichao Du Zhiyu Ren Jun Wu Wang Xi Honggang fu Institute of Theoretical chemistry Jilin University ChangChun 130023 China Key Laboratory of functional Inorganic Material Chemistry Ministry of Education of the People's Republic of China School of Chemistry and Materials Science Heilongjiang University Harbin 150080 China

Highly sensitive, selective, and stable hydrogen peroxide （H2O2） detection using nanozyme-based catalysts are desirable for practical applications. Herein, vertical α-FeOOH nanowires were successfully grown on the surface of carbon fiber paper （CFP） via a low-temperature hydrothermal procedure. The formation of vertical α-FeOOH nanowires is ascribed to the structure-directing role of sodium dodecyl sulfate. The resulting free-standing electrode with one-dimensional （1D） nanowires offers oriented channels for fast charge transfer, excellent electrical contact between the electrocatalyst and the current collector, and good mechanical stability and reproducibility. Thus, it can serve as an efficient electrocatalyst for the reduction and sensitive detection of H2O2. The relation of the oxidation current of H202 with the concentration is linear from 0.05 to 0.5 mM with a sensitivity of -0.194 mA/（***2） and a low detection limit of 18μM. furthermore, the portability in the geometric tailor and easy device fabrication allow extending the general applicability of this free-standing electrode to chemical and biological sensors.

关键词： α-FeOOH nanowires free-standing electrode synergistic effect electrocatalysis H2O2 detection

A linear complementarity model for multibody systems with frictional unilateral and bilateral constraints

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Acta Mechanica Sinica 2011年第4期27卷 587-592页

作者： Hai-Ping Gao Qi Wang Shi-Min Wang Li fu Department of dynamics and control Beihang University 100191 Beijing China

The Lagrange-I equations and measure differential equations for multibody systems with unilateral and bilateral constraints are constructed. For bilateral constraints, frictional forces and their impulses contain the products of the filled-in relay function induced by Coulomb friction and the absolute values of normal constraint reactions. With the time-stepping impulse-velocity scheme, the measure differential equations are discretized. The equations of horizontal linear complementarity problems （HLCPs）, which are used to compute the impulses, are constructed by decomposing the absolute function and the filled-in relay function. These HLCP equations degenerate into equations of LCPs for frictional unilateral constraints, or HLCPs for frictional bilateral constraints. Finally, a numerical simulation for multibody systems with both unilateral and bilateral constraints is presented.

关键词： Coulomb friction Bilateral constraint Unilat-eral constraint - Horizontal linear complementarity problem(HLCP) Time-stepping impulse-velocity algorithm

Comparative investigation on high-speed grinding of TiCp/Ti–6Al–4V particulate reinforced titanium matrix composites with single-layer electroplated and brazed CBN wheels

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Chinese Journal of Aeronautics 2016年第5期29卷 1414-1424页

作者： Li Zheng Ding wenfeng Shen Long Xi Xinxin fu Yucan College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics

In order to develop the high-efficiency and precision machining technique of TiCp/Ti - 6Al-4V particulate reinforced titanium matrix composites （PTMCs）, high-speed grinding experiments were conducted using the single-layer electroplated cubic boron nitride （CBN） wheel and brazed CBN wheel, respectively. The comparative grinding performance was studied in terms of grinding force, grinding temperature, grinding-induced surface features and defects. The results display that the grinding forces and grinding temperature obtained with the brazed CBN wheel are always lower than those with the electroplated CBN wheel. Though the voids and microcracks are the dominant grinding-induced surface defects, the brazed CBN wheel produces less surface defects compared to the electroplated wheel according to the statistical analysis results. The max mum materials removal rate with the brazed CBN wheel is much higher than that with the electroplated one. All above indicate that the single-layer brazed CBN super-abrasive wheel is more suitable for high-speed grinding of PTMCs than the electroplated counterpart.

关键词： High-speed grinding PTMCs Single-layer brazed CBNwheel Single-layer electroplated CBN wheel Surface defects

Fe(III)-Catalyzed Aerobic Oxidation of 1,4-Diols

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Chinese Journal of Chemistry 2023年第16期41卷 1963-1966页

作者： Junlin Li Jinxian Liu Chunling fu Shengming Ma Laboratory of Molecular Recognition and Synthesis Department of ChemistryZhejiang UniversityHangzhouZhejiang 310027China

Comprehensive Summary Aerobic oxidation has been catching more and more attention because of its atom economy and environmental *** of diols is a challenge due to various oxidative ***,highly selective aerobic oxidation affording specific products is of current *** this work,a combination of Fe(NO_(3))_(3)·9H_(2)O/TEMPO/KCl catalysis has been identified as an efficient recipe for the aerobic oxidation of 1,4-diols affordingγ-butyrolactones under mild *** reaction exhibits decent chemo-and regioselectivity of symmetrical and unsymmetrical 1,*** optically activeγ-lactones may also be prepared from optically active 1,4-diols without erosion of the ee via this ***,this approach was successfully applied to synthesize NBP,a commercial drug.

关键词： Aerobic oxidation 1,4-Diol γ-Lactone Catalysis lron TEMPO KCI Chemoselectivity Chirality Selective oxidation

Effects of aspect ratio on flapping wing aerodynamics in animal flight

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Acta Mechanica Sinica 2014年第6期30卷 776-786页

作者： Jun-Jiang fu Csaba Hefler Hui-He Qiu Wei Shyy Department of Mechanical and Aerospace Engineering The Hong Kong University of Science & Technology

Morphology as well as kinematics is a critical determinant of performance in flapping *** understand the effects of the structural traits on aerodynamics of bioflyers,three rectangular wings with aspect ratios（AR）of1,2,and 4 performing hovering-like sinusoidal kinematics at wingtip based Reynolds number of 5 300 are experimentally *** structures on sectional cuts along the wing span are *** K-H instability is found on the leading edge vortex of wings with higher aspect *** bursting only appears on the outer spanwise locations of high-aspect-ratio *** vortex bursting on high-aspect-ratio wings is perhaps one of the reasons why bio-flyers normally have low-aspect-ratio *** analysis exhibits larger dimensionless circulation of the leading edge vortex（LEV）over higher aspect ratio wings except when vortex bursting *** average dimensionless circulation of AR1 and AR2 along the span almost equals the dimensionless circulation at the 50%*** flow structure and the circulation analysis show that the sinusoidal kinematics suppresses breakdown of the LEV compared with simplified flapping kinematics used in similar *** Reynolds number effect results on AR4 show that in the current Re range,the overall flow structure is not sensitive to Reynolds number.

关键词： Aspect ratio Aerodynamics Leading edge vortex Flapping wing

Highly enantioselective construction of CF_(3) -bearing all-carbon quaternary stereocenters: Chiral spiro-fused bisoxazoline ligands with 1,1'-binaphthyl sidearm for asymmetric Michael-type Friedel-Crafts reaction

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Chinese Chemical Letters 2022年第5期33卷 2415-2419页

作者： Robert Li-Yuan Bao Lei Shi Kang fu School of Science Harbin Institute of TechnologyShenzhen 518055China State Key Laboratory of Elemento-Organic Chemistry Nankai UniversityTianjin 300071China Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and TechnologyShenzhen 518055China School of Chemistry and Chemical Engineering Harbin Institute of TechnologyHarbin 150001China

A novel class of chiral spiro-fused bisoxazoline ligands possessing a deep chiral pocket was *** developed ligands have been employed in the nickel-catalyzed highly enantioselective Michael-type Friedel-Crafts reaction, affording the products bearing a trifluoromethylated all-carbon quaternary stereocenter with moderate to excellent yields(up to 99%) and good to excellent enantioselectivies(up to> 99.9% ee). Moreover, a proposed model of chiral pocket revealed that the attack of indole from the Re-face of β-CF_(3)-β-disubstituted nitroalkene was favorable.

关键词： Chiral bisoxazoline ligand Chiral pocket Chiral spiro ligand Friedel-Crafts reaction Trifluoromethylated all-carbon quaternary stereocenter

平台运动对声学导航圆交汇模型的影响及误差分析

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电子与信息学报 2020年第7期42卷 1652-1660页

作者：付进李静孙思博哈尔滨工程大学水声技术重点实验室哈尔滨150001 工业和信息化部海洋信息获取与安全工信部重点实验室(哈尔滨工程大学) 哈尔滨150001 哈尔滨工程大学水声工程学院哈尔滨150001 青岛海纳水下信息技术有限公司青岛266400

声学导航技术被广泛应用于水下机动平台的自主导航。常用的声学导航模型多为圆交汇模型,该模型结构简单,计算方便,但未考虑平台运动影响,是一种静止模型。平台运动条件下,平台接收各水下声信标(水下星站节点)的时间及所处空间位置不同,... 详细信息

声学导航技术被广泛应用于水下机动平台的自主导航。常用的声学导航模型多为圆交汇模型,该模型结构简单,计算方便,但未考虑平台运动影响,是一种静止模型。平台运动条件下,平台接收各水下声信标(水下星站节点)的时间及所处空间位置不同,即时间和空间存在差异性,会产生模型失配,影响导航精度。针对上述问题,该文推导了由平台运动造成的模型失配误差公式,定量分析了运动对导航精度的影响以及误差的空间分布规律,着重研究了航速、航向角等航行参数对导航精度的影响规律,并进行了仿真验证。研究结果表明:仅考虑平台运动的影响时,声学导航圆交汇模型的失配误差存在,且与平台在阵内的空间位置有关,其导航精度空间特性呈近似的同心椭圆分布;模型失配误差还与平台航行参数有关,模型失配误差对速度变化敏感,随着航行速度增大,呈近似线性趋势增大,影响严重;航向角对全局精度变化范围影响小,主要影响模型失配误差的空间分布,体现为一种随航向角"旋转"的特性,且椭圆横轴方向与平台运动方向趋于一致。

关键词：声学导航圆交汇模型水下运动平台模型失配误差分析

Investigation of the Influence of Inclination Angle and Diffusion Angle on the Film Cooling Performance of Chevron Shaped Hole

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Journal of Thermal Science 2018年第6期27卷 580-591页

作者： fu Zhongyi ZHU Huiren LIU Cunliang WEI Jiansheng ZHANG Bolun School of Power and Energy Northwestern Polytechnical University

The film cooling performance of chevron holes with different inclination angles and exit lateral diffusion angles has been studied experimentally and numerically. The inclination angles include 35° and 55°. The exit lateral diffusion angles include 20° and 25°. The film cooling effectiveness, heat transfer coefficient and discharge coefficient were measured on a flat plate model by transient liquid crystal measurement technique under four blowing ratios. The results show that the large inclination angle reduces the film cooling effectiveness. The influence of diffusion angle has two aspects: the large diffusion angle leads to mainstream ingestion and decreases film cooling effectiveness at M=1.0 and 1.5; however, the large diffusion angle increases the film cooling effectiveness at high blowing ratio of 2.0, because the larger hole exit area decreases the normal momentum component of the film jet. The large inclination angle decreases the heat transfer coefficient in the right downstream region at M=0.5 and 1.0. The large diffusion angle enhances the heat transfer in the right downstream of the holes in M=0.5～1.5 conditions. The chevron hole with large inclination angle generally has the highest discharge coefficient.

关键词： film cooling effectiveness heat transfer coefficient chevron shaped hole inclination angle diffusion angle