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Numerical Study on Influence of key parameters of Aerodynamic Characteristics of Shaftless Ducted Rotor

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Transactions of Nanjing University of Aeronautics and Astronautics 2020年第5期37卷 682-693页

作者： SHEN Suiyuan ZHU Qinghua WANG Kun CHEN Jianwei ZENG Jianan DING Zhengyuan National key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

Shaftless ducted rotor(SDR)is a new type of ducted rotor system designed with ducted-rotor-motor integration,which is quite different from traditional ducted rotor(DR)in aerodynamic *** sliding mesh based on unstructured grid is used to simulate the aerodynamic characteristics of SDR and ***,the effects of five key parameters,namely,the rotor disk height,the number of blades,the spread angle of the duct,the central hole radius and the ducted lip radius on the aerodynamic characteristics of the SDR are *** is found that the same-sized SDR produces a larger total lift than the DR in hovering,but the lift proportion of its duct is *** the forward flight,a large low-speed region is generated behind the SDR duct,and the reflux vortex in blade root above the advancing blade has the trend for inward *** rotor disk height has similar effects on SDR and *** the number of blades can effectively increase the total lift of SDR,which also increases the lift proportion of *** the spread angle of the duct will lead to the rotor lift coefficient decrease,reducing the central hole radius can increase the total lift,but the component lift coefficient *** increasing the ducted lip radius can increase the total lift,which begins to decrease after reaching a certain value.

关键词： shaftless ducted rotor ducted-rotor-motor integration ducted rotor sliding mesh key parameters aerodynamic characteristics

Status and trends in the stability of the three largest ice shelves in Antarctica

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Science China Earth Sciences 2024年第8期67卷 2615-2632页

作者： Rongxing LI Guojun LI Lu AN Menglian XIA Da LV Yuan CHENG Aiguo ZHAO Tian CHANG Xiangbin CUI Shengkai ZHANG Shijie LIU Yixiang TIAN Weian WANG Center for Spatial Information Science and Sustainable Development Applications Tongji UniversityShanghai 200092China College of Surveying and Geo-informatics Tongji UniversityShanghai 200092China Postdoctoral Research Station of Shanghai Surveying and Mapping Institute Shanghai 200063China key Laboratory of Spatial-temporal Big Data Analysis and Application of Natural Resources in Megacities Shanghai 200063China Institute for Conservation of Cultural Heritage School of Cultural Heritage and Information ManagementShanghai UniversityShanghai 200444China Polar Research Institute of China Shanghai 200136China Chinese Antarctic Center of Surveying and Mapping Wuhan UniversityWuhan 430079China

The Ross,Filchner-Ronne,and Amery ice shelves are the three largest ice shelves in Antarctica,playing a crucial role in supporting the Antarctic ice ***,current studies on the stability of the three largest ice shelves primarily focus on singular or limited factors,lacking a comprehensive assessment of multiple *** systematically and in-depth study the stability and trend of the three largest ice shelves,we comprehensively collected and analyzed key parameters,including elevation changes,basal melting,surface meltwater,major rifts propagation rate,suture zones,ice front area change rate,grounding lines,ice velocity,and mass ***,we selected the collapsed Larsen B Ice Shelf(LBIS),the rapidly changing and structurally weakened Pine Island Ice Shelf(PIIS),and the accelerating Totten Ice Shelf(TIS)as reference ice *** comparing and analyzing the key parameters between these reference ice shelves and the three largest ice shelves,we find the status and trends in the stability of the *** findings reveal that most key parameters of the three largest ice shelves present relatively minor variations compared to those of the reference ice ***,50%of the parameters are smaller than those of the accelerating TIS,88%are smaller than those of the rapidly changing PIIS,and all parameters are smaller than those of the collapsed ***,after analyzing parameters that are not smaller than those of the TIS,it is observed that they remain in a stable ***,the three largest ice shelves are currently undergoing natural changes that do not threaten their stability in the short ***,the evolution of the ice shelves under global climate change remains uncertain,making long-term observation and monitoring essential to assess their impact on sea level rise.

关键词： Three largest ice shelves in Antarctica key parameters Remote sensing monitoring Ice shelf stability Sea level change

Parameter sensitivity analysis of the axial stability for a marine flexible pipe

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Petroleum 2024年第3期10卷 548-556页

作者： Liping Tang Jiaxin Zou Kenan Song Yongheng Shi Li Liu School of Mechatronic Engineering Southwest Petroleum UniversityChengdu610500China School of Engineering University of AberdeenAberdeenAB243UEUK Oil&Gas Control Center National Petroleum and Natural Gas Pipeline Network Group Co.Ltd.Beijing100020China

Marine unbonded flexible pipes serve as the most essential equipment in offshore oil and gas exploration and *** compressive loads during installation or in service in the complex marine environment usually lead to buckling failure.A flexible pipe is a composite structure with multiple functional layers,of which the tensile armor layer plays a key role with regard to the response of the pipe subjected to axial *** this paper,a simplified three-dimensional finite element model is developed,focusing on the tensile layer and replacing the carcass layer,pressure sheath layer,and pressure armor layer by a cylindrical rigid body to reduce computational *** using this model,the buckling failure modes of the tensile armor layer(in particular the birdcaging phenomenon)are *** key parameters that affect the stability of the flexible pipe under axial compression and torsion are emphasized,and their effects on its axial and torsional stiffness are compared and *** results show that both the lay angle of the steel wires and the interlayer friction coefficient have a significant influence on the axial and torsional stiffness of the pipe,whereas the damaged length of the outer sheath has virtually no effect.

关键词： Flexible pipe Tensile armor Buckling failure key parameters Stiffness

Numerical analysis of non-Newtonian rheology effect on hydrocyclone flow field

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Petroleum 2015年第1期1卷 68-74页

作者： Lin Yang Jia-Lin Tian Zhi Yang You Li Chuan-Hong Fu Yong-Hao Zhu Xiao-Lin Pang School of Mechanical Engineering Southwest Petroleum UniversityChengdu 610500China School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

In view of the limitations of the existing Newton fluid effects on the vortex flow mechanism study,numerical analysis of non Newton fluid effects was *** Reynolds stress turbulence model(RSM)and mixed multiphase flow model(Mixture)of FLUENT(fluid calculation software)and combined with the constitutive equation of apparent viscosity of non-Newtonian fluid,the typical non-Newtonian fluid(drilling fluid,polymer flooding sewage and crude oil as medium)and Newton flow field(water as medium)were compared by quantitative *** on the research results of water,the effects of non-Newtonian rheology on the key parameters including the combined vortex motion index n and tangential velocity were *** study shows that:non-Newtonian rheology has a great effect on tangential velocity and n value,and tangential velocity decreases with non-Newtonian *** three kinds of n values(constant segment)are:0.564(water),0.769(polymer flooding sewage),0.708(drilling fluid)and their variation amplitudes are larger than Newtonian *** same time,non-Newtonian rheology will lead to the phenomenon of turbulent drag reduction in the vortex flow *** with the existing formula calculation results shown,the calculation result of non-Newtonian rheology is most consistent with the simulation result,and the original theory has large *** study provides reference for theory research of non-Newtonian cyclone separation flow field.

关键词： Non-Newtonian rheology Cyclone separation key parameters Turbulent drag reduction FLUENT