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Effect of inlet elbow on rotation stall in waterjet ppropulsionpump

Fundamental Research 2024年第4期4卷 898-906页

作者： Wei Li Shuo Li Leilei Ji Enda Li Weidong Shi Ramesh Agarwal Muhammad Awais National Research Center of Pumps Jiangsu UniversityZhenjiang 212013China institute of Fluid engineering Equipment Technology Jiangsu UniversityZhenjiang 212009China College of Mechanical engineering Nantong UniversityNantong 226019China departmentof Mechanical engineering&Materials Science Washington University in StLouisSt.LouisMO6330US.

To study the influence of an elbow inlet on the rotating stall characteristics of a waterjet propulsion pump(WJPP),a three-dimensional internal flow field in a WJPP under a straight-pipe inlet and elbow inlet is numerically *** comparing the hydraulic performance of WJPP under the two inlet conditions,the internal relationship between the inlet mode and the flow pattern in the pump is *** on unsteady pressure fluctuation characteristics and wavelet analysis,the influence of the inlet mode on the rotating stall is revealed,and the stall transient propagation characteristics under critical stall conditions are *** disturbance effects of the inlet channel geometry disappear under low flow rate conditions,the main disturbance is induced by the highspeed countercurrent,and the flow pattern under the elbow inlet is better than that under the straight-pipe *** the straight-pipe inlet,the single-stall nucleus in the WJPP temporarily experiences a low-frequency and high-amplitude disturbance,which subsequently transforms into a mode of multi-stall nuclei with high-frequency circumferential *** the elbow inlet,the rotating stall always maintains a mode of high-amplitude and low-frequency disturbance,which represents the transient characteristics of a single stall core propagating in the circumferential direction inside the *** results of this study have a reference value for structural design optimization in a WJPP.

关键词： Waterjet propulsion pump Inlet condition Rotation stall Flow structure Pressurefluctuation

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Customized scaffolds for large bone defects using 3D‑printed modular blocks from 2D‑medical images

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Bio-Design and Manufacturing 2024年第1期7卷 74-87页

作者： Anil AAcar Evangelos Daskalakis Paulo Bartolo Andrew Weightman Glen Cooper Gordon Blunn Bahattin Koc Faculty of engineering and Natural Sciences Sabanci UniversityIstanbul 34956Türkiye D Bioprinting Laboratory Sabanci University Nanotechnology Research and Application CenterIstanbul 34956Türkiye School of Mechanical Aerospace and Civil EngineeringManchester Institute of BiotechnologyUniversity of ManchesterManchester M139PLUK Singapore Centre for 3D Printing School of Mechanical and Aerospace EngineeringNanyang Technological UniversitySingapore 639798Singapore School of Pharmacy and Biomedical Sciences University of PortsmouthPortsmouth PO12UPUK

Additive manufacturing(AM)has revolutionized the design and manufacturing of patient-specific,three-dimensional(3D),complex porous structures known as scaffolds for tissue engineering *** use of advanced image acquisition techniques,image processing,and computer-aided design methods has enabled the precise design and additive manufacturing of anatomically correct and patient-specific implants and ***,these sophisticated techniques can be timeconsuming,labor-intensive,and ***,the necessary imaging and manufacturing equipment may not be readily available when urgent treatment is needed for trauma *** this study,a novel design and AM methods are proposed for the development of modular and customizable scaffold blocks that can be adapted to fit the bone defect area of a *** modular scaffold blocks can be combined to quickly form any patient-specific scaffold directly from two-dimensional(2D)medical images when the surgeon lacks access to a 3D printer or cannot wait for lengthy 3D imaging,modeling,and 3D printing during *** proposed method begins with developing a bone surface-modeling algorithm that reconstructs a model of the patient’s bone from 2D medical image measurements without the need for expensive 3D medical imaging or *** algorithm can generate both patient-specific and average bone ***,a biomimetic continuous path planning method is developed for the additive manufacturing of scaffolds,allowing porous scaffold blocks with the desired biomechanical properties to be manufactured directly from 2D data or *** algorithms are implemented,and the designed scaffold blocks are 3D printed using an extrusion-based AM *** and instructions are also provided to assist surgeons in assembling scaffold blocks for the self-repair of patient-specific large bone defects.

关键词： Additive manufacturing Modular scaffolds Large bone defect Customized scaffold design Patient-specific scaffolds

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频带禁区:远离共振的管道设计策略

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Acta Mechanica Sinica 2024年第3期40卷 191-201页

作者：邓天昌丁虎 Shanghai Key Laboratory of Mechanics in Energy engineering School of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China Shanghai institute of Aircraft Mechanics and Control Shanghai200092China

本文介绍了一种通过调整卡箍使得管道避免发生共振的设计策略.当管道的固有频率在机械设备运作时产生的振动频率范围内,会引发共振现象,给机械设备的正常操作带来严重的灾难.因此,把机械设备操作产生的振动频率范围定义为频带禁区.通常... 详细信息

本文介绍了一种通过调整卡箍使得管道避免发生共振的设计策略.当管道的固有频率在机械设备运作时产生的振动频率范围内,会引发共振现象,给机械设备的正常操作带来严重的灾难.因此,把机械设备操作产生的振动频率范围定义为频带禁区.通常,工程中的管道被简化为多跨输流管道:通过将卡箍简化为线性和扭转刚度,建立了多跨输流管道的整体管道模型.通过采用Galerkin截断方法并应用广义特征值方法,获得了多跨输流管道的固有频率.通过对比不同长度的管道固有频率和频带禁区,定义了管长的安全范围和共振范围分别为频带禁区的外和内,并且通过分析卡箍的影响推导得出了绝对安全长度和绝对共振长度.此外,还确定了卡箍刚度和位置对安全范围的影响.结果表明,通过调整卡箍的线性刚度、扭转刚度和位置,管道的安全范围会发生显著地变化.根据这些结果,提出了一种管道设计策略,从而避免了管道的共振发生,并减少了使用卡箍的数量.最后,以飞机上的一段管道为例进行了设计,结果表明:通过调整卡箍,管道的固有频率成功地远离了频带禁区,因而在飞机的运行过程中不会发生共振.总而言之,通过调整卡箍的刚度或位置,可以获得避免多跨输流管道发生共振的设计策略.

关键词： Pipe conveying fluid Frequency preserve Natural frequency Resonance Multispan Retaining clip

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Utilization of Basalt Saw Mud as a Spherical Porous Functional Aggregate for the Preparation of Ordinary Structure Concrete

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 364-375页

作者：周永祥关青锋 LENG Faguang WANG Jing LI Tianjun Faculty of Architecture Civil and Transportation EngineeringBeijing University of TechnologyBeijing 100124China Key Laboratory of Urban Security and Disaster engineering of Ministry of Education Beijing University of TechnologyBeijing 100012China School of Materials Science and engineering Southeast UniversityNanjing 211189China institute of Building Materials China Academy of Building ResearchBeijing 100013China State Key Laboratory of Building Safety and Built Environment Beijing 100013China Zhejiang Chinavigor E.P.Technology Co. Ltd.Zhejiang 315043China

To promote the production and application of artificial aggregates,save natural sand resources and protect the ecological environment,we evaluated the feasibility of using spherical porous functional aggregates(SPFAs) formed by basalt saw mud under autoclave curing in ordinary structural *** our work,two types of prewetted functional aggregates were taken as replacements for natural aggregates with different volume substitution rates(0%,5%,10%,15%,20%,25%,and 30%) in the preparation of ordinary structural concrete with water-to-binder ratios(W/B) of 0.48 and *** effects of the functional aggregate properties and content,W/B,and curing age on the fluidity,density,mechanical properties and autogenous shrinkage of ordinary concrete were *** experimental results showed that the density of concrete declined at a rate of not more than 5%,and the 28 d compressive strength could reach 31.0-68.2 *** W/B,long curing age and high-quality functional aggregates were conducive to enhancing the mechanical properties of SPFAs *** the rolling effects,SPFAs can optimize the particle gradation of aggregate systems and improve the fluidity of concrete,and the water stored inside SPFAs provides an internal curing effect,which prolongs the cement hydration process and considerably reduces the autogenous shrinkage of *** exhibits high strength and high density,as well as being more cost-effective and ecological,and is expected to be widely employed in ordinary structural concrete.

关键词： lightweight concrete civil concrete building basalt saw mud fly ash internal curing environmentally friendly

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节流式燃氧分离固体发动机准一维内弹道数值研究

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Acta Mechanica Sinica 2024年第1期40卷 85-101页

作者：王立民王富祺王志邦王英男王革关奔周星 College of Aerospace Science and engineering National University of Defense TechnologyChangsha 410073China Inner Mongolia Dynamic and Mechanical institute Hohhot 010011China College of Aerospace and Civil engineering Harbin Engineering UniversityHarbin 150001China College of engineering Peking UniversityBeijing 100871China

本文建立了用于计算节流式燃氧分离固体发动机内弹道的准一维数值模型。节流式燃氧分离固体发动机通过改变富燃燃烧室和富氧燃烧室之间的节流阀开口半径来实现其推力的调节。数值模型采用简化的反应机理来描述化学非平衡过程,且考虑了... 详细信息

本文建立了用于计算节流式燃氧分离固体发动机内弹道的准一维数值模型。节流式燃氧分离固体发动机通过改变富燃燃烧室和富氧燃烧室之间的节流阀开口半径来实现其推力的调节。数值模型采用简化的反应机理来描述化学非平衡过程,且考虑了燃烧室中的质量添加、壁面摩擦和推进剂燃面退移过程。利用该数值模型展示了节流式燃氧分离固体发动机的内部流动参数分布和工作性能.发动机稳定工作状态结果显示,当节流阀开度半径由10.5mm调节至1.4mm时,发动机推力由121.82N增加至250.60N,推力提升了206%,验证了节流式燃氧分离固体发动机概念的可行性.流动参数也表明节流阀的调节作用仅在阀门开度较小时才得以充分体现.发动机动态工作过程结果显示,在调节阀停止作动时,节流式燃氧分离固体发动机性能会产生负调现象,因而需要对发动机采取额外的保护措施.对节流式燃氧分离固体发动机调节能力的理论预测发现,发动机的推力调节能力受限于富燃燃烧室压力和初始质量流量比,需要在多个参数之间进行权衡以实现合理的推力调节比.最后对推进剂的布置方式进行了初步探讨结果表明,燃氧推进剂布置下发动机的推力调节能力优于氧燃推进剂布置。

关键词：固体发动机化学非平衡燃烧室压力阀门开度质量流量比流动参数节流阀开度准一维

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A STAMP-Game model for accident analysis in oil and gas industry

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Petroleum Science 2024年第3期21卷 2154-2167页

作者： Huixing Meng Xu An Daiwei Li Shijun Zhao Enrico Zio Xuan Liu Jinduo Xing State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of TechnologyBeijing100081China School of Emergency Management and Safety engineering China University of Mining and Technology(Beijing)Beijing100083China Energy Department Politecnico di MilanoVia La Masa 34Milan20156Italy Mines Paris PSL Centre de Recherche sur les Risques et les CrisesSophie Antipolis06904France School of Mechanical-Electronic and Vehicle engineering Beijing University of Civil Engineering and ArchitectureBeijing100044China

Accidents in engineered systems are usually generated by complex socio-technical *** is beneficial to investigate the increasing complexity and coupling of these factors from the perspective of system *** on system and control theories,System-Theoretic Accident Model and Processes(STAMP)is a widely recognized approach for accident *** this paper,we propose a STAMP-Game model to analyze accidents in oil and gas storage and transportation *** in accident analysis by STAMP can be regarded as players of a *** theory can,thus,be adopted in accident analysis to depict the competition and cooperation between ***,we established a game model to study the strategies of both supervisory and supervised *** obtained results demonstrate that the proposed game model allows for identifying the effectiveness deficiency of the supervisory entity,and the safety and protection altitudes of the supervised *** STAMP-Game model can generate quantitative parameters for supporting the behavior and strategy selections of the supervisory and supervised *** quantitative data obtained can be used to guide the safety improvement,to reduce the costs of safety regulation violation and accident risk.

关键词： Accident analysis STAMP System engineering Gametheory Oil and gas storage and transportation systems

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Highly Strong,Tough,and Cryogenically Adaptive Hydrogel Ionic Conductors via Coordination Interactions

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Research 2024年第3期2024卷 703-713页

作者： Zhuomin Wang Siheng Wang Lei Zhang He Liu Xu Xu institute of Chemical Industry of Forestry Products Key Laboratory of Biomass Energy and MaterialJiangsu ProvinceKey Laboratory of Chemical Engineering of Forest ProductsNational Forestry and Grassland AdministrationNational Engineering Research Center of Low-Carbon Processing and Utilization of Forest BiomassJiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest ResourcesChinese Academy of ForestryNanjing 210042China College of Chemical engineering Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest ResourcesNanjing Forestry UniversityNanjing 210037China.

Despite the promise of high flexibility and conformability of hydrogel ionic conductors,existing polymeric conductive hydrogels have long suffered from compromises in mechanical,electrical,and cryoadaptive properties due to monotonous functional improvement strategies,leading to lingering ***,we propose an all-in-one strategy for the preparation of poly(acrylic acid)/cellulose(PAA/Cel)hydrogel ionic conductors in a facile yet effective manner combining acrylic acid and salt-dissolved cellulose,in which abundant zinc ions simultaneously form strong coordination interactions with the two polymers,while free solute salts contribute to ionic conductivity and bind water molecules to prevent ***,the developed PAA/Cel hydrogel simultaneously achieved excellent mechanical,conductive,and cryogenically adaptive properties,with performances of 42.5 MPa for compressive strength,1.6 MPa for tensile strength,896.9%for stretchability,9.2 MJ m^(−3)for toughness,59.5 kJ m^(−2)for fracture energy,and 13.9 and 6.2 mS cm^(−1)for ionic conductivity at 25 and−70°C,*** by these features,the resultant hydrogel ionic conductor is further demonstrated to be assembled as a self-powered electronic skin(e-skin)with high signal-to-noise ratio for use in monitoring movement and physiological signals regardless of cold temperatures,with hinting that could go beyond high-performance hydrogel ionic conductors.

关键词： Highly freezing salts

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Rational Design of Ruddlesden-Popper Perovskite Ferrites as Air Electrode for Highly Active and Durable Reversible Protonic Ceramic Cells

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Nano-Micro Letters 2024年第9期16卷 308-324页

作者： Na Yu Idris Temitope Bello Xi Chen Tong Liu Zheng Li Yufei Song Meng Ni Department of Building and Real Estate Research Institute for Sustainable Urban Development(RISUD)and Research Institute for Smart Energy(RISE)The Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China The Hong Kong Polytechnic University Shenzhen Research institute Shenzhen 518057GuangdongPeople’s Republic of China Department of Mechanical and Aerospace engineering The Hong Kong University of Science and TechnologyClear Water BayHong KongPeople’s Republic of China

Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode ***-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting ***,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting *** study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen *** D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling *** approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.

关键词： Reversible protonic ceramic cells Air electrode Ruddlesden-Popper perovskite Hydration Oxygen reduction reaction

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22 kW near-diffraction-limited Yb:YAG slab laser amplifier without adaptive optics correction

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Chinese Optics Letters 2024年第3期22卷 65-70页

作者：汪丹何平周唐建李密邬映臣王亚楠尚建力高清松张凯唐淳朱日宏 School of Electronic and Optical engineering Nanjing University of Science and TechnologyNanjing 210094China institute of Applied Electronics China Academy of Engineering PhysicsMianyang 430079China Graduate School of China Academy of engineering Physics Beijing 100193China

A high-power CW Yb:YAG slab laser amplifier with no adaptive optics correction has been experimentally *** room temperature,the amplifier emits a power of 22 kW with an average beam quality(β)of less than 3 in 0.5 *** our knowledge,this is the brightest slab laser without closed-loop adaptive optics demonstrated to *** addition,an extracted power of 17 kW with an optical extraction efficiency of 33%,corresponding to a residual optical path difference of less than 0.5μm,is achieved with the single Yb:YAG slab gain *** slab gain module has the potential to be scalable to higher powers while maintaining good beam *** makes a high-power solid-state laser system simpler and more robust.

关键词： laser amplifier Yb:YAG slab laser surface quality pumping uniformity

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Numerical simulation on sand sedimentation and erosion characteristics around HDPE sheet sand barrier under different wind angles

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Journal of Mountain Science 2024年第2期21卷 538-554页

作者： ZHANG Kai ZHANG Peili ZHANG Hailong TIAN Jianjin WANG Zhenghui XIAO Jianhua College of Civil engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster *** disasters,characterized by multi-directional wind patterns,result in diverse angles among the *** this study,using numerical simulations,we examined the behavior of High Density Polyethylene(HDPE)sheet sand barriers under different wind angles,focusing on flow field distribution,windproof efficiency,and sedimentation erosion *** study discovered that at a steady wind speed,airflow velocity varies as the angle between the airflow and the HDPE barrier ***,a 90°angle results in the widest low-speed airflow area on the barrier’s downwind *** the airflow is not perpendicular to the barrier,it prompts a lateral airflow movement which decreases as the angle *** windproof efficiency correlates directly with this angle but inversely with the wind’s ***,with a wind angle of 90°,wind speed drops by 81%.The minimum wind speed is found at 5.1H(the sand barrier height)on the barrier’s downwind *** the angle grows,the barrier’s windproof efficiency improves,extending its protective *** is most prominent on the barrier’s downwind side,as the wind angle shifts from 30°to 90°,the sand sedimentation area on the barrier’s downwind side enlarges by *** the angle grows,sedimentation intensifies,eventually overtakes the forward erosion and enlarges the sedimentation area.

关键词： Multi-wind direction HDPE sheet sand barrier Numerical simulation Windproof efficiency Sedimentation erosion

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