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Chinese Journal of Aeronautics 2024年第5期37卷 506-519页

作者： Jiwen SHEN Weijing KONG zhengyang xu Yongbin ZENG Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The surface integrity of metal micro-hole structures produced by electrochemical discharge machining is unsatisfactory owing to the insufficient reaction area and strength of electrolysis action.A novel ultrahigh-speed Rotary Electrochemical Discharge Machining(R-ECDM)using non-water-based electrolyte is proposed to improve surface integrity by changing the breakdown medium of spark discharge and increasing the reaction area and strength of electrolysis.A mathematical model was developed to establish the relationship between rotational speed and forces acting on the *** on the magnitude of forces,controlling rotational speed changed the behavior and departure radius of bubbles on the cathode ***-speed photographs validate that,in the mathematical model,the number and departure radius of bubbles on the cathode surface gradually decrease with the increase of rotational *** experimental results show that the roughness(Ra)of the micro-hole sidewall decreases from 2.54μm to 0.20μm when the rotational speed increases from 500 r/min to 40000 r/*** length loss and wear ratio of the cathode are only 9.75μm and 6.5%,***,the micro-holes array with recast-free and surface roughness of 0.20μm is fabricated,demonstrating that the proposed approach contributes to improving surface integrity of metal micro-holes.

关键词： Electrochemical discharge machining Micro-holes Recast layer Ultrahigh-speed rotary Bubbles Force analysis Non-water-based solution

Evaluation of embedded modular branched stent graft in treating aortic arch aneurysm using imaging-based computational flow analysis

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Medicine in Novel Technology and Devices 2024年第1期21卷 80-87页

作者： xuehuan Zhang Jiang Xiong Wei Ma Lijuan xue zhengyang xu Hongpeng Zhang Yongsheng Wang Duanduan Chen Wei Guo School of Medical Technology Beijing Institute of TechnologyBeijingChina Department of Vascular and Endovascular Surgery The First Medical Center of Chinese PLA General HospitalBeijingChina Department of Vascular and Endovascular Surgery Hainan HospitalChinese PLA General HospitalHainanChina Department of Radiology The First Medical Center of Chinese PLA General HospitalBeijingChina Hangzhou Endonom Medtech Co. LtdZhejiangChina

Embedded modular branched stent graft(EMBSG)was a new option for aortic arch ***,the therapeutic effect of this innovative stenting technique has not been fully *** fluid dynamics and three-dimensional structural analyses were performed on three patients(Patient Ⅰ,Patient Ⅱ and Patient Ⅲ)with aortic arch aneurysm,both before and after EMBSG ***-specific alterations from preoperative to postoperative were analyzed via morphological and functional *** Ⅰ and Patient Ⅱ showed notable curvature changes and area reduction after intervention *** patients showed an increase in flow velocity after EMBSG implantation,while the pressure drop from ascending aorta to the aortic arch was remarkable in Patient I and Patient Ⅱ with the value of 7.09mmHg,and 10.95mmHg,*** I and Patient Ⅱ also showed elevated time-averaged wall shear stress(TAWSS)in the stenting region,while Patient Ⅲ showed a trivial change in TAWSS after intervention *** patients showed low relative residence time after EMBSG *** short-term results of EMBSG in treating aortic arch aneurysm were *** parameters have the potential to assist in the outcome evaluation and might be used to guide the stent graft design and wise selection,thereby improving the long-term therapeutic effect in managing complex vascular disease.

关键词： Aortic archaneurysm Embedded modular branched stent graft Endovascul araorti carch repair Computational fluid dynamics Functional evaluation

PHBV-硫铁矿基人工湿地处理实际污水处理厂尾水混合营养反硝化研究

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北京大学学报（自然科学版） 2024年第2期60卷 315-328页

作者：许正阳周琦贾利霞吴为中邢传宏郑州大学生态与环境学院郑州450001 北京大学环境科学与工程学院北京100871

以河南省新乡市某大型污水处理厂尾水为研究对象,开展模拟人工湿地尾水深度脱氮除磷研究。选用聚羟基丁酸戊酸酯(PHBV)和硫铁矿作为湿地系统的主要功能填料,构建异养反硝化与自养反硝化相结合的混合营养反硝化系统。通过水质指标监测和... 详细信息

以河南省新乡市某大型污水处理厂尾水为研究对象,开展模拟人工湿地尾水深度脱氮除磷研究。选用聚羟基丁酸戊酸酯(PHBV)和硫铁矿作为湿地系统的主要功能填料,构建异养反硝化与自养反硝化相结合的混合营养反硝化系统。通过水质指标监测和高通量测序等手段,探究工艺运行效果与微生物群落结构机制。构建PHBV+硫铁矿组(实验组)和PHBV+陶粒组(对照组),反应器连续运行77天,结果表明,当水力停留时间(HRT)为2小时,进水水质为NO_(3)^(−)-N=8.39±1.72 mg/L,TN=10.41±1.58 mg/L,TP=0.37 mg/L,COD=15.7 mg/L时,平均出水TN浓度达到2.22 mg/L,TP浓度达到0.28 mg/L,COD浓度为32.7 mg/L,PHBV+硫铁矿组人工湿地脱氮效率(78.55%)明显优于PHBV+陶粒组(51.25%),基本上达到地表水环境质量标准(GB 3838—2002)V类。微生物群落结构分析表明,PHBV+硫铁矿组人工湿地中的优势菌属为自养菌Desulfobacter和异养菌unclassified_k__norank_d__Bacteria,丰度分别为23.98%和12.30%,通过自养与异养菌的协同,实现混合营养反硝化,其中与硫代谢相关Desulfobacter主导的自养反硝化在系统脱氮中可能起主要作用。研究结果可为PHBV+硫铁矿基人工湿地尾水生物脱氮除磷的工程实践提供参考。

关键词：人工湿地尾水固相碳源硫铁矿混合营养反硝化

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基于联络馈线负载率松弛约束的中压配电网供电单元划分

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电力自动化设备 2024年第7期44卷 108-115页

作者：刘洪王浩嘉徐正阳王冰赛马良杨帆天津大学智能电网教育部重点实验室天津300072 国网经济技术研究院有限公司北京102209 国网天津市电力公司经济技术研究院天津300171

当前中压配电网供电单元划分时未能充分考虑相互联络馈线间所供负荷的互补特性,易造成供电单元数量偏多、整体线路利用效率偏低等问题,为此提出了一种基于负载率松弛约束的供电单元划分方法。构建了以供电单元数量最少、各供电单元内N-... 详细信息

当前中压配电网供电单元划分时未能充分考虑相互联络馈线间所供负荷的互补特性,易造成供电单元数量偏多、整体线路利用效率偏低等问题,为此提出了一种基于负载率松弛约束的供电单元划分方法。构建了以供电单元数量最少、各供电单元内N-1校验后转供馈线负载率均衡为目标的中压配电网供电单元划分数学模型;解析了网格中站内供电单元与站间供电单元之间的划分次序问题,并提出了基于馈线负载率松弛约束的站间供电单元划分方法及以此为基础的站内供电单元划分方法。通过实例分析验证所提模型和方法可以对供电单元进行合理划分,节约变电站出线条数与供电单元数量,有效提高配电线路的资产利用效率。

关键词：中压配电网供电网格供电单元负荷特性负载率松弛

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Numerical and Experimental Investigation on Photothermal Performance of Polyimide/High-Electrical-Performance-Coating Composite Films Considering Surface Roughness

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Journal of Thermal Science 2022年第4期31卷 1206-1219页

作者： JING Peng ZHOU Xiao xu zhengyang xu Zhiguo School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China Sunman(Zhenjiang)Co. LtdZhenjiang 212000China

Polyimide(PI)films are the common and important components on spacecraft for thermal *** parameter design accuracy has an important impact on the spacecraft thermal balance but there are few studies focusing on the effect of film surface *** the present study,photothermal properties of composite films made of PI films and germanium/indium tin oxide/aluminum coatings are obtained by UV-VIS-NIR *** film surface morphology of composite films is obtained by the atomic force *** present study creatively introduces surface roughness into modeling from the perspective of finite-difference time-domain(FDTD)*** FDTD method considering surface roughness is used to present a comprehensive investigation on the coating effect on the photothermal properties including transmittance and reflectance of composite *** on the random rough surface generated by root-mean-square(RMS)roughness and correlation length,the FDTD method is applied to characterize the electromagnetic field of composite *** has been found that the numerical accuracy is greatly improved and the numerical results agree well with the experimental data when surface roughness is *** results also show that coating material and thickness have remarkable impacts on photothermal properties of the composite films.

关键词： FDTD composite film surface roughness photothermal property coating material

Improving profile accuracy and surface quality of blisk by electrochemical machining with a micro inter-electrode gap

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Chinese Journal of Aeronautics 2023年第4期36卷 523-537页

作者： Jingtao WANG zhengyang xu Di ZHU College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Electrochemical machining(ECM)has emerged as an important option for manufacturing the *** inter-electrode gap(IEG)distribution is an essential parameter for the blisk precise shap-ing process in ECM,as it affects the process stability,profile accuracy and surface *** IEG leads to a poor localization effect and has an adverse influence on the machining accuracy and surface quality of *** achieve micro-IEG(<50 lm)blisk finishing machining,this work puts forward a novel variable-parameters blisk ECM strategy based on the synchronous coupling mode of micro-vibration amplitude and small pulse *** modelling and simulation of the blisk micro-IEG machining have been carried *** experiments of variable-parameters blisk ECM were car-ried *** results illustrated that the IEG width reduced with the progress of variable parameter *** IEG width of the blade’s concave part and convex part could be successfully controlled to within 30 lm and 21 lm,*** profile deviation for the blade’s concave surface and convex surface are 49 lm and 35 lm,while the surface roughness reaches R_(a)=0.149 lm and R_(a)=0.196 lm,*** profile accuracy of the blisk leading/trailing edges was limited to within 91 ***-pared with the currently-established process,the profile accuracy of the blade’s concave and convex profiles was improved by 50.5%and 53.3%,*** surface quality was improved by 53.2%and 50.9%,***,the machined surface was covered with small corrosion pits and weak attacks of the grain boundary due to selective *** electrolytic products were dispersed on the machined surface,and their components were mainly composed of the carbide and oxide products of Ti and Nb *** results indicate that the variable-parameters strategy is effective for achieving a tiny IEG in blisk ECM,which can be used in engineering practice.

关键词： Electrochemical machining Blisk IEG Machining quality Surface quality

Breakthrough detection in electrochemical discharge drilling to enhance machining stability

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Chinese Journal of Aeronautics 2023年第6期36卷 460-475页

作者： Tianyu GENG zhengyang xu Chenxiang ZHANG Jin NING College of Mechanical&Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Film cooling holes are widely used in aero-engine turbine *** blades feature large numbers of holes with complex angles and require a high level of surface *** discharge drilling(ECDD)combines the high efficiency of electrical discharge drilling(EDD)with high quality of electrochemical drilling(ECD).However,due to the existence of a variety of energy for material removal,accurate and timely detection of breakthroughs is fraught with *** insufficient preset setting distance results in a tiny exit aperture,influencing the structure's *** addition,the electrode is prone to bending at a large overfeeding distance,causing secondary discharge damaging sidewall surface *** paper compares and analyzes the characteristics of processing waveforms using EDD and ECDD.A novel breakthrough detection method is proposed based on the variance signal of average voltage(VSAV)to increase machining stability and achieve fabrication without a recast *** method extracts the fluctuation transformation by calculating the variance of the *** signal detection,the overfeeding distance is *** experiment is used to validate the breakthrough detection with 100%accuracy in all *** optimum overfeeding distances for hole angles of 0°,30°,and 60° are obtained,and the stable removal of the recast layer is ***,the effectiveness of the method is verified on a typical workpiece with a double-wall structure and a nickel-based single crystal blade.

关键词： Change detection Electrochemical discharge drilling(ECDD) Electric discharge Film cooling holes Recast layer Variance signal of average voltage(VSAV)

Dependency of the pulsed electrochemical machining characteristics of Inconel 718 in NaNO_(3)solution on the pulse current

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Science China(Technological Sciences) 2022年第10期65卷 2485-2502页

作者： WANG JingTao xu zhengyang GENG TianYu ZHU Di College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Pulsed electrochemical machining(PECM)has attracted increasing interest as a technique to improve material dissolution localization and surface *** work systematically investigates the effects of pulse current on the surface morphology,profile accuracy,and corrosion behavior of Inconel 718(IN718)in NaNO_(3)*** behavior reveals that IN718 in NaNO_(3)solution during pulse current machining exhibited significant passive,transpassive,and re-passive *** passive film generated at the re-passive state contained some oxides and had a loose porous *** critical value for the quantity of electric charge to rupture the passive film was determined to be 26.88℃cm^(−2).The current efficiency indicates that the material removal rate of IN718 in NaNO_(3)solution during pulse current machining was *** PECM experiments indicate that the loading process of the electrical double layer was prolonged with an increased workpiece scale,i.e.,the loading process of the electrical double layer lasted for the entire pulse-on time when the workpiece scale was 100 mm^(2)at a frequency of more than 10 kHz regardless of the duty cycle.A pulse current with a short pulse length and short pulse period improved the profile accuracy,as did the low applied voltage and small workpiece *** dissolution mechanism of IN718 in NaNO_(3)solution was also investigated based on the effective pulse current ***,the leading-edge structure of a ruled blade with good dimensional accuracy and surface quality was successfully *** maximum deviations of the machined profile were effectively restricted within 0.057 mm,and the surface roughness was Ra=0.358μm.

关键词： pulsed electrochemical machining corrosion behavior current efficiency blade leading edge machining quality

Electrochemical cutting of mortise-tenon joint structure by rotary tube electrode with helically distributed jet-flow holes

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Chinese Journal of Aeronautics 2022年第2期35卷 376-387页

作者： Tao YANG Xiaolong FANG Xiaoyun HU zhengyang xu Yongbin ZENG Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In aero-engines,mortise-tenon joint structures are often used to connect the blades to the turbine *** disadvantages associated with conventional manufacturing techniques mean that a low-cost,high-efficiency,and high-quality nickel-based mortise–tenon joint structure is an urgent requirement in the field of aviation *** cutting is a potential machining method for manufacturing these parts,as there is no tool degradation in the cutting process and high-quality surfaces can be *** realize the electrochemical cutting of a mortise-tenon joint structure,a method using a tube electrode with helically distributed jet-flow holes on the side-wall is *** feeding,the tube electrode rotates along its central *** field simulations show that the rotational speed of the tube electrode determines the direct spraying time of the high-speed electrolyte ejected from the jet-flow holes to the machining area,while the electrolyte pressure determines the flow rate of the electrolyte and the velocity of the electrolyte ejected from the jet-flow *** machining results using the proposed method are verified experimentally,and the machining parameters are ***,mortise and tenon samples are successfully machined using 20 mm thick Inconel 718 alloy with a feeding rate of 5μm/s.

关键词： Electrochemical cutting Helically distributed holes Jet-flow holes Mortise-tenon joint structure Rotary tube electrode

Electrochemical machining of complex components of aero-engines: Developments, trends, and technological advances

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Chinese Journal of Aeronautics 2021年第2期34卷 28-53页

作者： zhengyang xu Yudi WANG National Key Laboratory of Science and Technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Because of several advantages, such as no tool wear, independence on the mechanical properties of the material, and high machining efficiency, electrochemical machining(ECM) has become a viable method for machining components in numerous industrial applications, particularly in the manufacture of typical aero-engine components with complex structures fabricated from materials that are difficult to cut. This paper highlights the current developments, new trends, and technological advances of key factors of ECM, such as electrochemical dissolution characteristics of novel difficult to cut materials which are often used in aero-engine, numerical simulation of electrochemical process, design for the complex profile and structure of cathode tool, flow field simulation and design for uniform electrolyte flow, and innovation of electrochemical machining or hybrid methods which reflect the state of the art in academic and industrial research on electrochemical machining in aero-engine manufacturing.

关键词： Aeroengine Electrochemical machining Hybrid machining Machining process Manufacturing Nontraditional machining