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Controlling secondary flow in high-lift low-pressure turbine using boundary-layer slot suction

Chinese Journal of Aeronautics 2024年第3期37卷 21-33页

作者： Xiao QU liunan li Yingjie ZHANG Xingen LU Junqiang ZHU Yanfeng ZHANG School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory of light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing 100190China

The design of high-lift Low-Pressure Turbines(LPTs)causes the separation of the boundary layer on the suction side of the blade and leads to a strong secondary *** present study aims to minimize secondary losses through endwall slot suction and incoming wakes in a front-loaded high-lift LPT cascade with Zweifel of 1.58 under low Reynolds number of *** slotted schemes for the boundary layer of the endwall were designed(Plan A and Plan B),and the effects of suction mass flow on secondary flow were *** underlying physics of the endwall boundary layer of the suction and secondary flow under unsteady wakes was *** results show that slot suction at the endwall boundary layer can significantly suppress the secondary flow by removing low-momentum *** A and B significantly reduced the secondary kinetic energy by 44.2%and 36.9%,respectively,compared with the baseline cascade at the suction mass flow ratios of 1%.With an increase in the mass flow ratio of suction,the secondary flow was gradually reduced in both Plans A and *** is more beneficial to control the secondary flow to destroy the intersection of the pressure side and suction side of the horseshoe vortex before it develops into a passage *** unsteady wakes,the combined effects of incoming wakes and endwall boundary layer suction can further suppress the secondary flow at the suction mass flow ratios of 2%for Plan A,because the positive and negative vorticity inside upstream wakes accelerated the mixing of the main flow and secondary flow and thus increased the energy of secondary vortices.

关键词： Low-pressure turbine Secondary flow Flow control Boundary-layer suction Incoming wake

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Adaptive observer-based integral event-triggered antivibration control of a full aircraft active landing gear system with irregular runway excitations

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Science China(Information Sciences) 2024年第6期67卷 248-261页

作者： Wenxiao HU Chenglong DU Fanbiao li Xinmin CHEN Chunhua YANG Weihua GUI School of Automation Central South University Research Center in System Engineering for Special Aircrafts Ningbo Institute of Materials Technology and EngineeringChinese Academy of Sciences

This study addresses the antivibration issue of a full aircraft active landing gear system(LGS)under landing impact and runway excitations via a novel adaptive observer-based integral event-triggered control method. First, a full aircraft active LGS comprising a front gear and two synchronized main left and right gears with active suspensions is established, where the information exchange among them is not implemented directly. Second, two adaptive observers are designed separately for the front and main LGSs to identify the varying damping parameters and estimate the system states simultaneously. Third, estimated states are transmitted to a shared network through a novel integral event-triggered mechanism(I-ETM);thus, the front and main LGSs are interconnected, and a networked control scheme for the aircraft LGS is constructed. Additionally, the integrated active control law is designed with the aid of the transmitted states of the front and main LGSs, enhancing the robustness against the pitch vibration of the ***, the L2-stability of the hybrid system is guaranteed to depress the vertical vibration effect of the landing impact and irregular runway excitations, thus improving passenger safety and comfort. Moreover,a codesign method is provided to obtain feasible solutions to the gain matrices of the observers and controllers simultaneously. Simulation and comparison results are presented to illustrate the effectiveness and superiority of the proposed control scheme in antivibration and saving communication resources.

关键词： aircraft active landing gear antivibration control integral event-triggered mechanism adaptive observer ${\mathcal{L}}_2$-stability

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Deep decalcification of factory-provided freezing acidolysis solution to achieveα-high-strength gypsum

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Chinese Journal of Chemical Engineering 2024年第5期69卷 143-151页

作者： Wencai Ye Yulu li Yonggang Dong lin Yang Yun Yi Jianxin Cao School of Chemistry and Chemical Engineering Guizhou UniversityGuiyang 550025China Engineering Research Center of Efficient Utilization for Industrial Waste Guizhou UniversityGuiyang 550025China Key Laboratory of Guizhou Province for Green Chemical Industry and Clean Energy Technology Guizhou UniversityGuiyang 550025China

The freezing acidolysis solution of the nitric acid-phosphate fertilizer process has a high calcium content,which makes it difficult to produce fine phosphate and high water-soluble phosphate fertilizer ***,based on the potential crystallization principle of calcium sulfate in NH_(4)NO_(3)-H_(3)PO_(4)-H_(2)O,the deep decalcification(*** removal)technology to achieveα-high-strength gypsum originated from freezing acidolysis-solutions has been firstly proposed and ***,calcium can be removed from the factory-provided freezing acidolysis-solution by neutralizing it with ammonia,followed by the addition of ammonium sulfate *** a result,the formation of calcium sulfate in the reaction system undergoes the nucleation and growth of CaSO_(4)·2H_(2)O(DH),as well as its dissolution and crystallization into short columnarα-CaSO_(4)·0.5H_(2)O(α-HH).Remarkably,with the molar ratio of SO_(4)^(2-)/Ca^(2+)at 1.8,the degree of neutralization(NH_(3)/HNO_(3) molar ratio)at 1.7,the reaction temperature of 94℃,and the reaction time of 300 min,the decalcification rate can reach 86.89%,of which the high-strengthα-CaSO_(4)·0.5H_(2)O(α-HH)will be ***,the deep decalcification product meets the standards for the production of fine phosphates and highly water-soluble phosphate ***,the 2 h flexural strength ofα-HH is 5.3 MPa and the dry compressive strength is 36.8 MPa,which is up to the standard of commercialα-HH.

关键词： Nitrophosphate Ammonia neutralization Deep decalcification High-strengthα-hemihydrate gypsum Controlled crystallization at atmospheric pressure

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Theoretical and Experimental Study on the Performance of Hermetic Diaphragm Squeeze Film Dampers for Gas-Lubricated Bearings

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 151-169页

作者： Jianwei Wang Haoxi Zhang Shaocun Han Hang li Peng Wang Kai Feng State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

Low damping characteristics have always been a key sticking points in the development of gas *** application of squeeze film dampers can significantly improve the damping performance of gas lubricated *** paper proposed a novel hermetic diaphragm squeeze film damper(HDSFD)for oil-free turbomachinery supported by gas lubricated *** types of HDSFDs with symmetrical structure were proposed for good damping *** considering the compressibility of the damper fluid,based on hydraulic fluid mechanics theory,a dynamic model of HDSFDs under medium is proposed,which successfully reflects the frequency dependence of force *** on the dynamic model,the effects of damper fluid viscosity,bulk modulus of damper fluid,thickness of damper fluid film and plunger thickness on the dynamic stiffness and damping of HDSFDs were *** experimental test rig was assembled and series of experimental studies on HDSFDs were *** damper fluid transverse flow is added to the existing HDSFD concept,which aims to make the dynamic force coefficients independent of *** the force coefficient is still frequency dependent,the damping coefficient at high frequency excitation with damper fluid supply twice as that without damper fluid *** results serve as a benchmark for the calibration of analytical tools under development.

关键词： Hermetic diaphragm squeeze film damper Compressibility Dynamic model Experimental studies

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Study of the blocking mechanism in gravel packing based on CFD-DEM

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Particuology 2024年第7期90卷 164-178页

作者： Fucheng Deng Lei Wen Gang li Baitao Fan Ning Gong Shenghong Chen Yangtze University Jingzhou434023China Guangzhou Institute of Energy Conversion Chinese Academy of Sciences510640China CNOOC Research Institute Ltd Beijing100028China Tianjin Branch of CNOOC Ltd Tianjin300459China CNOOC Ener Tech-Drilling&Production Co Tianjin300457China

Gravel packing sand control(GPSC),as the optimization of mechanical sand control technology,is widely used in the deep water completion and sand control of loose sandstone heavy oil reservoirs and highly *** explore the blocking mechanism of GPSC,the influence of its structural parameters on the blocking of GPSC is *** paper establishes a particle element model based on computational fluid dynamics-discrete element method coupling using the discrete element method and establishes a fluid flow model combined with computational fluid dynamics to realize their full coupling *** sand control experiments were carried out using a micro visual sand control simulation device to verify the blocking *** blocking mechanism is analyzed from the microscopic point of view,and then,the influence of sand control structure parameters on the blocking in GPSC design is *** results show the following:(1)the blocking process of GPSC can be divided into three stages:an initial stage,sand accumulation stage,and equilibrium stage.(2)There are two main types of gravel packing *** first type of blocking is blocking on the surface of the gravel *** particles on the surface of gravel layer mainly exist in the form of large particle size blocking gravel pores and sand particles bridging each *** second type of blockage is the blockage inside the gravel *** particles mainly exist in the form of internal mud cakes and adsorption on gravels inside the gravel layer.(3)To ensure the sand control performance of the gravel layer,the gravel layer thickness is designed between 23 and 28 *** displacement or pressure of the on-site packing pump should be increased to ensure that the gravel layer packing solidity ranges between 59%and 62%.In the design of GPSC,it should be ensured that the median particle size of gravel is 5–6 times the median particle size of *** study provides an effective technical reference for the

关键词： CFD-DEM Blocking the process Blocking mechanism Structural parameter

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Microstructure Modification and Ductility Improvement for TaMoNbZrTiAl Refractory High Entropy Alloys via Increasing Ti Content

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Acta Metallurgica Sinica(English Letters) 2024年第7期37卷 1186-1200页

作者： Yujing Zhou Siyi Peng Yueling Guo Xiaoxiang Wu Changmeng liu Zhiming li School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China Shagang School of Iron and Steel Soochow UniversitySuzhou215137China School of Materials Science and Engineering Central South UniversityChangsha410083China

Here, the composition of TaMoNbZrTiAl refractory high entropy alloy (RHEA) is optimized by increasing Ti content to improve its mechanical property especially the ductility, through comparing two RHEAs with different Ti content. The RHEAs contain two body-centered-cubic (BCC) phases. The BCC phase in the dendritic region is rich in Ta, Mo and Nb, and the BCC phase in the interdendritic region is enriched in Zr, Ti and Al. The as-cast RHEA with a higher Ti content remains dendritic microstructures, and Ti is mainly enriched in the interdendritic region. After annealing treatment at 1300 ℃ for 48 h, the dendritic microstructures change into equiaxed-grain morphology, accompanied by needle-like micron precipitates at grain boundaries in the RHEA with higher Ti content. For the as-cast RHEAs, the fracture strain increases by ~ 6.6% and the uniform plastic strain increases by ~ 5.9% at the compression test due to the increase of Ti content. Our work offers a reference for the composition design of RHEAs and makes a preliminary exploration of the optimization of the microstructures and mechanical properties.

关键词： Refractory high entropy alloys Solidification Grain morphology Microstructure Mechanical property

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Bioinspired Scraper-File Type Frequency-Doubling Ultrasonic Exciter

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Journal of Bionic Engineering 2024年第4期21卷 1801-1816页

作者： Wenshuai Wu Mingshuo Zhang Zeming li Guang Yao Xinggang Jiang Deyuan Zhang School of Mechanical Engineering and Automation Beihang UniversityBeijing100191China Institute of Bionic and Micro-Nano Systems Beihang UniversityBeijing100191China Guangdong Provincial Key Laboratory of Minimally Invasive Surgical Instruments and Manufacturing Technology Guangdong University of TechnologyGuangzhou510006China

In the natural world,leaf-cutting ants cause vibrations through their mutual scraping of file-scraper *** this study,we designed a Biomimetic Ultrasonic Exciter(BUE)that imitates leaf-cutting *** operating characteristics of the BUE were studied through experimental testing and finite element *** results showed that the BUE could generate stable ultrasonic vibrations,and that the excitation frequency only needed to be half the Output Frequency(OF).This frequency-doubling phenomenon was conducive to achieving BUE *** further explore the phenomenon of frequency-doubling vibration output,this study designed scrapers of five different sizes,conducted excitation and first-order natural frequency measurement tests,and the corresponding finite element *** was found that each scraper could operate in frequency-doubling mode,but the operating frequency and natural mode frequencies did not correspond with one *** further explicate experimental and simulation results,a two-degrees-of-freedom vibration model was *** was evident that the contact relationship between the dentate disc and scraper introduced strong nonlinear factors into the system,accounting for the frequency-doubling phenomenon and the difference between the BUE’s operating and mode *** BUE could be expected to facilitate the production of high-power micro-ultrasonic generators and has potential application value in the fields of mechanical processing,industrial production,and medical health.

关键词： Leaf-cutting ants Power ultrasound Nonlinear vibration Ultrasonic scalpel Micro vibrator

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High-entropy materials:Excellent energy-storage and conversion materials in the field of electrochemistry

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Particuology 2024年第9期92卷 42-60页

作者： Jincan li Huiyu Duan Qi Long Bianjiang Zhang Changyun Chen Huan Pang Key Laboratory of Advanced Functional Materials of Nanjing School of Environmental ScienceNanjing Xiaozhuang UniversityNanjing211171China School of Chemical Engineering Institute for Innovative Materials and EnergyYangzhou UniversityYangzhou225009China

High-entropy materials(HEMs),a new type of materials,have attracted significant attention in the field of electrocatalytic reactions,batteries and energy-storage materials over the past few years owing to their unique structure,controllable elementary composition,and adjustable *** excellent characteristics result from four major factors:high entropy,sluggish-diffusion,severe lattice distortion,and cocktail effect,and are used widely in energy-energy *** review aims to summarize the recent progress of HEMs in electrochemical *** begin with the concept,structure,and four core effects of HEMs that provide the basic information on ***,we discuss the major properties of HEMs and analyze the relationship between their structures and ***,we highlight the outstanding performance of HEMs in hydrogen storage,electrode materials of batteries,catalysis,and supercapacitors,and briefly explain the mechanisms of these materials that are crucial in energy storage and *** review will assist in understanding the excellent energy-storage properties,intricacies of the phase structures,elemental interactions,and reaction mechanisms associated with ***,challenges and future development prospects are *** work will provide insight into the factors that are crucial for designing HEMs with energy storage properties.

关键词： High-entropy materials Hydrogen storage Electrode materials of batteries Catalyst Supercapacitor

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Chatter suppression techniques in milling processes:A state of the art review

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Chinese Journal of Aeronautics 2024年第7期37卷 1-23页

作者： Zhenmin li Qinghua SONG Peijian JIN Zhanqiang liU Bing WANG Haifeng MA Key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of EducationSchool of Mechanical EngineeringShandong UniversityJinan 250061China National Demonstration Center for Experimental Mechanical Engineering Education Shandong UniversityJinan 250061China

Chatter in the machining system can result in a decrease in tool life,poor surface finish,conservative cutting parameters,*** many review papers promoting the understanding and research of this area,chatter suppression techniques are generally discussed within limited pages in the framework of comprehensive chatter-related *** recent years,the developments of smart materials,advanced sensing techniques,and more effective control strategies have led to some new progress in chatter ***,the widely used thin-walled parts present more and more severe machining challenges in their milling *** the above deficiencies,this paper summarizes the current state of the art in milling chatter *** classifications of chatter suppression techniques are proposed according to the working principle and control *** on the new classified framework,the mechanism and comparisons of different chatter suppression strategies are ***,the current challenges and potential tendencies of milling chatter suppression techniques are ***,integration,compactness,adaptability to workpiece geometry,and the collaboration of multiple control methods are predicted to be important trends in the future.

关键词： Active control Chatter suppression Damping Milling Regenerative effect

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Interpretable data-driven fault diagnosis method for data centers with composite air conditioning system

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Building Simulation 2024年第6期17卷 965-981页

作者： Yiqi Zhang Fumin Tao Baoqi Qiu Xiuming li Yixing Chen Zongwei Han SEP Key Laboratory of Eco-Industry School of MetallurgyNortheastern UniversityShenyang110819China Energy Saving and Low-carbon Technology of Process Industry Engineering Research Center of liaoning Province Northeastern UniversityShenyang110819China College of Civil Engineering Hunan UniversityChangsha410082China

Fault detection and diagnosis are essential to the air conditioning system of the data center for elevating reliability and reducing energy *** study proposed a convolutional neural network(CNN)based data-driven fault detection and diagnosis model considering temporal dependency for composite air conditioning system that is capable of cooling the high heat flux in data *** input of fault detection and diagnosis model was an unsteady dataset generated by the experimentally validated transient mathematical *** dataset concerned three typical faults,including refrigerant leakage,evaporator fan breakdown,and condenser ***,the CNN model was trained to construct a map between the input and system operating ***,the performance of the CNN model was validated by comparing it with the support vector machine and the neural ***,the score-weighted class mapping activation method was utilized to interpret model diagnosis mechanisms and to identify key input features in various operating *** results demonstrated in the pump-driven heat pipe mode,the accuracy of the CNN model was 99.14%,increasing by around 8.5%compared with the other two *** the vapor compression mode,the accuracy of the CNN model achieved 99.9%and declined the miss rate of refrigerant leakage by at least 61%*** score-weighted class mapping activation results indicated the ambient temperature and the actuator-related parameters,such as compressor frequency in vapor compression mode and condenser fan frequency in pump-driven heat pipe mode,were essential features in system fault detection and diagnosis.

关键词： data center composite air conditioning system fault detection and diagnosis interpretable artificial intelligence

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