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Effect of impeller reflux balance holes on pressure and axial force of centrifugal pump

Journal of Central South University 2015年第5期22卷 1695-1706页

作者：曹卫东代珣胡啟祥 Technical and Research Center of Fluid Machinery Engineering Jiangsu University

The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low specific-speed centrifugal pump with Q=12.5 m3/h, H=60 m, n=2950 r/min was selected to be designed with eight axial reflux balance holes with 4.5 mm in diameter. The simulated Q-H curve and net positive suction head(NPSH) were in good agreement with experimental results, which illustrated that centrifugal pump with axial reflux balance holes was superior in the cavitation characteristic; however, it showed to little superiority in head and efficiency. The pressure in rear pump chamber at 0.6 times rate flow is 29.36% of pressure difference between outlet and inlet, which reduces to 29.10% at rate flow and 28.33% at 1.4 times rate flow. As the whole, the pressure distribution on front and rear shrouds from simulation results is not a standard parabola, and axial force decreases as flow rate increases. Radical reflux balance holes chosen to be 5.2 mm and 5.9 mm in diameter were further designed with other hydraulic parts unchanged. With structural grids adopted for total flow field, contrast numerical simulation on internal flow characteristics was conducted based on momentum equations and standard turbulence model(κ-ε). It is found that axial force of pump with radical reflux balance holes of5.2 mm and 5.9 mm in diameter is significantly less than that with radical reflux balance holes of 4.5 mm in diameter. Better axial force balance is obtained as the ratio of area of reflux balance holes and area of sealing ring exceeds 6.

关键词： centrifugal pump low specific-speed radical reflux balance holes numerical simulation pressure gradient axial force

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Semi-analytic solution of Eringen's two-phase local/nonlocal model for Euler-Bernoulli beam with axial force

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Applied Mathematics and Mechanics(English Edition) 2018年第12期39卷 1805-1824页

作者： Licheng MENG Dajun ZOU Huan LAI Zili GUO Xianzhong HE Zhijun XIE Cunfa GAO Facility Design and Instrumentation Institute China Aerodynamics Research and Development Center State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

Eringen’s two-phase local/nonlocal model is applied to an Euler-Bernoulli nanobeam considering the bending-induced axial force, where the contribution of the axial force to bending moment is calculated on the deformed state. Basic equations for the corresponding one-dimensional beam problem are obtained by degenerating from the three-dimensional nonlocal elastic equations. Semi-analytic solutions are then presented for a clamped-clamped beam subject to a concentrated force and a uniformly distributed load, respectively. Except for the traditional essential boundary conditions and those required to be satisfied by transferring an integral equation to its equivalent differential form, additional boundary conditions are needed and should be chosen with great caution, since numerical results reveal that non-unique solutions might exist for a nonlinear problem if inappropriate boundary conditions are used. The validity of the solutions is examined by plotting both sides of the original integro-differential governing equation of deflection and studying the error between both sides. Besides, an increase in the internal characteristic length would cause an increase in the deflection and axial force of the beam.

关键词： nonlocal elasticity internal characteristic length size effect nanobeam axial force unique solution

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Horizontal dynamic response of a large-diameter pipe pile considering the second-order effect of axial force

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Earthquake Engineering and Engineering Vibration 2018年第3期17卷 567-579页

作者： Luan Lubao Ding Xuanming Zhou Wei Zheng Changjie Qu Liming Key Laboratory of New Technology for Construction of Cities in Mountain Area College of Civil EngineeringChongqing UniversityChongqing 400045China Powerchina Chengdu Engineering Corporation Limited Chengdu 611130China

The second-order effect of axial force on horizontal vibrating characteristics of a large-diameter pipe pile is theoretically investigated.Governing equations of the pile-soil system are established based on elastodynamics.Threedimensional wave equations of soil are decoupled through differential transformation and variable separation.Consequently,expressions of soil displacements and horizontal resistances can be obtained.An analytical solution of the pile is derived based on continuity conditions between the pile and soil,subsequently from which expressions of the complex impedances are deduced.Analyses are carried out to examine the second-order effect of axial force on the horizontal vibrating behavior of the pipe pile.Some conclusions can be summarized as follows： stiffness and damping factors are decreased with the application of axial force on the pile head; distributions of the pile horizontal displacement and rotation angle are regenerated due to the second-order effect of the applied axial force; and redistributions of the bending moment and shearing force occur due to the second-order effect of the applied axial force.

关键词： axial force second-order effect horizontal vibration pipe pile analytical solution

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Mobility matrix of a weakly coupled parallel multi-DIM isolator based on axial force solution

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High Technology Letters 2020年第3期26卷 335-341页

作者：李德胜 Yu Jiangtao Huang Baowang Li Zhanxian Wang Zhijun College of Mechanical Engineering North China University of Science and TechnologyTangshan 063210P.R.China

A mobility matrix modeling strategy based on axial force solution for a weakly coupled parallel multi-dimentional(multi-DIM)isolator is proposed.Mobility power flow and transmissibility through the isolator are derived from the mobility matrix.Comparison between simulation and experimental results shows the correctness of the proposed modeling strategy.

关键词： mobility matrix weak-coupling parallel multi-dimentional(multi-DIM)isolator axial force mobility power flow

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A Combined-Power Model for the Distribution of axial force in Shaft Anchor along Its Length

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Journal of China University of Geosciences 2006年第1期17卷 89-94页

作者：卫军周锡武朱玉罗昕 Civil Engineering Department Huazhong University of Science and Technology Wuhan430074 China Civil Engineering Department Huazhong University of Science and Technology Wuhan430074 ChinaChina Communications Second Highway Survey Design and Research Institute Wuhan430052 China

The theoretical results of axial force distribution models differ greatly from tests because of the complication of the rock type material. A three-parameter combined-power model is proposed by curves fitting the test data recorded from the pull tests on anchoring bars used in different engineering projects. Based on the comparison of the mechanical characteristics of shaft anchors and prestressed tendons, a two-parameter combined-power function model for prestressed tendons is proposed. The bounded length derived from the model and the suggested values of the parameters are also proposed. Compared with the Gaussian model, the three-parameter combined-power model is more precise and simple in expression. Results also suggest that the bounded length calculated from the average stress method is not safe enough.

关键词： axial force prestress tendon bounded length combined-power model Gaussian model

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Numerical evaluation of segmental tunnel lining with voids in outside backfill

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Underground Space 2022年第5期7卷 786-797页

作者： Jia-Xuan Zhang Ning Zhang Annan Zhou Shui-Long Shen Department of Civil Engineering School of Naval ArchitectureOceanand Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China MOE Key Laboratory of Intelligent Manufacturing Technology Department of Civil and Environmental EngineeringCollege of EngineeringShantou UniversityShantouGuangdong 515063China Discipline of Civil and Infrastructure School of EngineeringRoyal Melbourne Institute of Technology(RMIT)Victoria 3001Australia

This paper presents a numerical investigation of the mechanical behaviour of segmental linings owing to the existence of voids in the composite lining.The composite lining was formed by mining outside and shield tunnelling inside with backfill in between.Finite element method was conducted to analyse the axial forces and bending moment for voids of different diameters at different positions.The results show that the axial forces in the transverse section increase near the crown and then invert and decrease on the left and right sides with an increase in the void centre angle(β)measured from the vertical axis.The increase in void diameter(daxial force on the left and right sides when β=45°and 90°,while it decreases near the crown and invert.The occurrence of voids leads to an increase in the bending moment in the entire segment section with an angle β.

关键词： Jointly constructed tunnel Composite lining Voids axial force Bending moment

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Angle of covered self-expandable metallic stents after placement is a risk factor for recurrent biliary obstruction

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World Journal of Hepatology 2022年第5期14卷 992-1005页

作者： Kojiro Tanoue Hirotsugu Maruyama Yuki Ishikawa-Kakiya Yosuke Kinoshita Kappei Hayashi Masafumi Yamamura Masaki Ominami Yuji Nadatani Shusei Fukunaga Koji Otani Shuhei Hosomi Fumio Tanaka Noriko Kamata Yasuaki Nagami Koichi Taira Toshio Watanabe Yasuhiro Fujiwara Department of Gastroenterology Osaka City University Graduate School of MedicineOsaka 545-8585Japan

BACKGROUND Studies have shown that covered self-expandable metallic stents(CSEMS)with a low axial forces after placement can cause early recurrent biliary obstruction(RBO)due to precipitating sludge formation.AIM To ascertain whether the angle of CSEMS after placement is a risk factor for RBO in unresectable distal malignant biliary obstruction(MBO).METHODS Between January 2010 and March 2019,261 consecutive patients underwent selfexpandable metallic stent insertion by endoscopic retrograde cholangiopancreatography at our facility,and 87 patients were included in this study.We evaluated the risk factors for RBO,including the angle of CSEMS after placement as the primary outcome.We measured the obtuse angle of CSEMS after placement on an abdominal radiograph using the SYNAPSE PACS system.We also evaluated technical and functional success,adverse events,time to RBO(TRBO),non-RBO rate,survival time,cause of RBO,and reintervention procedure as secondary outcomes.RESULTS We divided the patients into two cohorts based on the presence or absence of RBO.The angle of CSEMS after placement(per 1°and per 10°)was evaluated using the multivariate Cox proportional hazard analysis,which was an independent risk factor for RBO in unresectable distal MBO[hazard ratio,0.97 and 0.71;95%confidence interval(CI):0.94-0.99 and 0.54-0.92;P=0.01 and 0.01,respectively].For early diagnosis of RBO,the cut-off value of the angle of CSEMS after placement using the receiver operating characteristic curve was 130°[sensitivity,50.0%;specificity 85.5%;area under the curve 0.70(95%CI:0.57-0.84)].TRBO in the<130°angle group was significantly shorter than that in the≥130°angle group(P<0.01).CONCLUSION This study suggests that the angle of the CSEMS after placement for unresectable distal MBO is a risk factor for RBO.These novel results provide pertinent information for future stent management.

关键词： Covered self-expandable metallic stents Recurrent biliary obstruction Malignant biliary obstruction Endoscopic retrograde cholangiopancreatography Angle axial force

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Calculation Method of axial force in Hydrodynamic Torque Converter Based on Numerical Solution of Three-Dimensional Flow Field

Calculation Method of Axial Force in Hydrodynamic Torque Con...

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第五届流体传动与控制国际会议

作者： Ma Wengxing Liu Chunbao Xu Rui He Yandong College of Mechanical Science and Engineering Jilin University Changchun 130022 China

＜正＞A calculation method of axial force in hydrodynamic torque converter based on numerical solution of three-dimensional flow field is put forward. The typical three-element torque converter with cover wheel is taken as an instance and its axial force is calculated based on numerical solution of three-dimensional flow field.The calculation result shows that the method can be used to optimize the structure of hydrodynamic torque converter in order to reduce the axial force which is very important to make sure both bearing and hydrodynamic torque converter have a long lifetime.

关键词： torque converter axial force three-dimensional flow field

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Three-dimensional seismic isolation bearing and its application in long span hangars

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Earthquake Engineering and Engineering Vibration 2013年第1期12卷 55-65页

作者： Li Xiongyan Xue Suduo Cai Yancheng The College of Architecture and Civil Engineering Beijing University of Technology Department of Civil Engineering The University of Hong Kong

Based on the seismic response characteristics of space frame structures,a new type of seismic isolation bearing defined as a three-dimensional seismic isolation bearing（3DSIB） is developed in this paper.The bearing offers excellent properties such as multi-dimensional seismic isolation,reasonable rotation capability,good ability to resist lifting load,uncoupled stiffness in horizontal and vertical directions,etc.In the 3DSIB,the horizontal dimension is designed by combining the Teflon sliding device and helical spring,while the vertical dimension is developed by introducing disk springs or helical springs.The mathematical model of the 3DSIB was established and its performance with the critical parameters was tested on a shaking table.Furthermore,the 3DSIB was applied in a 120 m span hangar structure and simulated using SAP2000 software to evaluate its performance in practical structures.The performance of the structures with and without 3DSIB was compared.It is shown that the hangar structure with 3D bearings achieves a better performance.The axial force and acceleration response of the structures with 3DSIB are effectively reduced,while the displacement response of the bearing is within the predetermined range.

关键词： three-dimensional seismic isolation bearing （3DSIB） seismic isolation hangar axial force acceleration response

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Effect of Process Parameters on Tensile Strength of Friction Stir Welded Cast LM6 Aluminium Alloy Joints

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Journal of Materials Science & Technology 2009年第5期25卷 655-664页

作者： M.Jayaraman R.Sivasubramanian V.Balasubramanian Department of Mechatronics Engineering Kongu Engineering CollegeErodeTamil NaduIndia Department of Mechanical Engineering Coimbatore Institute of TechnologyCoimbatoreTamil NaduIndia Centre for Materials Joining&Research(CEMAJOR) Department of Manufacturing EngineeringAnnamalai UniversityAnnamalainagarTamil NaduIndia

This paper reports the effect of friction stir welding （FSW） process parameters on tensile strength of cast LM6 aluminium alloy. Joints were made by using different combinations of tool rotation speed, welding speed and axial force each at four levels. The quality of weld zone was investigated using macrostructure and microstructure analysis. Tensile strength of the joints were evaluated and correlated with the weld zone hardness and microstructure. The joint fabricated using a rotational speed of 900 r/min, a welding speed of 75 mm/min and an axial force of 3 kN showed superior tensile strength compared with other joints. The tensile strength and microhardness of the welded joints for the optimum conditions were 166 MPa and 64.8 Hv respectively.

关键词： LM6 aluminium alloy Friction stir welding Tool rotation speed Welding speed axial force Tensile strength

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