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misalignment analysis of journal bearing influenced by asymmetric deflection,based on a simple stepped shaft model

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第9期13卷 647-664页

作者： Zhen-peng HE Jun-hong ZHANG Wei-song XIE Zhou-yu LI Gui-chang ZHANG State Key Laboratory of Engine Tianjin UniversityTianjin 300072China Deparment of Mathematics School of ScienceTianjin University Tianjin 300072Ckina

The effects of journal misalignment on a journal bearing caused by an asymmetric rotor structure are presented in this study.A new model considering the asymmetric deflection is ***,the thermo-hydrodynamic of the oil film in the journal bearing and straightforward elasticity theory are considered in the *** on the structure stiffness equivalent characteristic,a simple stepped shaft can reflect the entire complex structure *** existing lubrication model,which does not consider this angle component,is not very precise for journal *** pressure,misalignment angle,velocity field,oil leakage,and temperature field were calculated and compared in the journal bearing *** results indicate that bearing performances are greatly affected by misalignment caused by the asymmetric structure.A simple stepped shaft can effectively represent a misaligned journal bearing in a rotor-bearing system.

关键词： misalignment Stepped shaft Asymmetric structure Journal bearing

Adaptive Prescribed Performance Control for Flexible Spacecraft with Input Saturation and Actuator misalignment

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Tsinghua Science and Technology 2019年第6期24卷 694-705页

作者： Jiawei Tao Tao Zhang Yongfang Nie Department of Automation Tsinghua UniversityBeijing 100084China Department of Strategic Missile and Underwater Weapon Naval Submarine AcademyQingdao 266071China

In this paper, a flexible spacecraft attitude control scheme that guarantees vibration suppression and prescribed performance on transient-state behavior is proposed. Here, parametric uncertainty, external disturbance, unmeasured elastic vibration, actuator saturation, and even configuration misalignment are considered. To guarantee prescribed performance bounds on the transient-and steady-state control errors, a performance constrained control law is formulated with an error transformed function. An elastic modal observer is employed to estimate the unmeasured flexible modal variables, and a command filter is adopted to avoid the tedious analytical computations of time derivatives of virtual control inherent in the control design. Subsequently, a novel auxiliary system is developed to compensate the adverse effects of the actuator saturation constraints, and a compensation term is integrated into the control law to tackle the configuration misalignment. A comparative simulation study is carried out to illustrate the effectiveness and advantages of the proposed approach.

关键词： flexible spacecraft modal observer vibration suppression prescribed performance input saturation actuator misalignment

Thermal analysis on the EAST tungsten plasma facing components with shaping structure counteracting the misalignment issues

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Plasma Science and Technology 2017年第2期19卷 108-114页

作者： Baoguo WANG Dahuan ZHU Rui DING Junling CHEN School of Nuclear Science and Technology University of Science and Technology of China Hefei 230026 People＇s Republic of China Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 People＇s Republic of China

Tungsten monoblock type tiles with ITER dimensions along with supporting cassette components were installed at EAST＇s upper diverter during 2014 and EAST＇s lower diverter will also be upgraded in the future. These cassette structures pose critical issues on the high cumulative incident heat flux due to the leading edges and misalignments （0 ～ 1.5 mm）, which may result in the destruction or even melting of the tungsten tile. The present work summarizes the thermal analysis using ANSYS multiphysics software 15.0 performed on the actively cooled W tiles to evaluate the shaping effect on surface temperature. In the current heat flux conditions （Q11 ～ 100 MW m-2）, the adopted chamfer shaping （1 ×1 mm） can only reduce the maximum temperature by about 14%, but it also has a melting risk at the maximum misalignment of 1.5 mm. The candidate shaping solutions elliptical （round） edge, dome and fish-scale are analyzed for comparison and are identified not as good as the dual chamfer structure. A relatively good dual chamfer （2 ×13 mm） shaping forming a symmetrical sloping roof structure can effectively counteract the 1.5 mm misalignment, reducing the maximum temperature by up to 50%. However, in the future heat flux conditions （Q11 ～287 MW m-2）, it may only endure about 0.5 mm misalignment. Moreover, no proper shaping solution has been found that can avoid melting at the maximum misalignment of 1.5 mm. Thus, the engineering misalignment has to be limited to an acceptable level.

关键词： EAST tungsten mono-block misalignment heat flux

Aerodynamic effects of impeller-diffuser axial misalignment in low-flow-coefficient centrifugal compressor

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Science China(Technological Sciences) 2015年第1期58卷 29-36页

作者： WANG ZhiHeng XI Guang LIU QingFang School of Energy and Power Engineering Xi'an Jiaotong University School of Mathmatics and Statistics Xi'an Jiaotong University

A numerical investigation on the aerodynamic effects of impeller-diffuser axial misalignment in the low-flow-coefficient centrifugal compressor is conducted through three-dimensional CFD *** results show that the flow,especially near the diffuser inlet,is influenced by the axial misalignment *** the impeller offsets to one side,the pressure at diffuser inlet close to this side will descend,and the vortex in the cavity on the other side will partially enter the diffuser and then result in the back *** performances of the stage and its components also change with the impeller-diffuser axial *** exists an optimum offset making the efficiency maximum at a given operating ***,the effect of impeller-diffuser axial misalignment on the axial thrust is *** axial thrust is nearly increased linearly with the increase of axial *** aerodynamic effects of impeller-diffuser axial misalignment in the low-flow-coefficient centrifugal compressor behaves more remarkably at the large flow *** alleviate the aerodynamic effects of impeller-diffuser misalignment,a rounding in the meridional plane at the diffuser inlet can be applied.

关键词： misalignment compressor low flow coefficient impeller

Model-Based Degree Estimation of Unbalance and misalignment in Flexible Coupling-rotor System

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Chinese Journal of Mechanical Engineering 2009年第4期22卷 550-556页

作者： LI Changyou XU Minqiang GUO Song WANG Yuewu WANG Rixin School of Astronautics Harbin Institute of Technology Harbin 150001 China School of Computer Science and Technology Harbin Engineering University Harbin 150001 China School ofMechanicalEngineering andAutomation Northeastern University Shenyang 110004 China

The condition of rotor system must be assessed in order to develop condition-based maintenance for rotating machinery. It is determined by multiple variables such as unbalance degree, misalignment degree, the amount of bending deformation of the shaft, occurrence of shaft crack of rotor system and so on. The estimation of the degrees of unbalance and misalignment in flexible coupling-rotor system is discussed. The model-based approach is employed to solve this problem. The models of the equivalent external loads for unbalance and misalignment are derived and analyzed. Then, the degrees of unbalance and misalignment are estimated by analyzing the components of the equivalent external loads of which the frequencies are equal to the 1 and 2 times running frequency respectively. The equivalent external loads are calculated according to the dynamic equation of the original rotor system and the differences between the dynamical responses in normal case and the vibrations when the degree of unbalance or misalignment or both changes. The denoise method based on bandpass filter is used to decrease the effect of noise on the estimation accuracy. The numerical examples are given to show that the proposed approach can estimate the degrees of unbalance and misalignment of the flexible coupling-rotor system accurately.

关键词： model-based approach degree estimation misalignment unbalance rotor system flexible coupling

Effect of angular misalignment on the static characteristics of rotating externally pressurized air journal bearing

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Science China(Technological Sciences) 2019年第9期62卷 1520-1533页

作者： SHI JiangHai CAO HongRui CHEN XueFeng School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049China State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong UniversityXi'an 710049China

This paper studies the effect of angular misalignment on the static characteristics of rotating externally pressurized air journal bearing with four degrees of freedom(4-DOF). A clearance function is used to describe the film thickness of air journal bearings with angular misalignment along two perpendicular directions. The finite different method(FDM) and an iterative procedure are applied to solve the Reynolds equation and obtain the air film pressure distribution. Various eccentricity ratios and rotating speeds are taken into considerations for the comparisons of static performances of the air journal bearing under different tilt angles. The results show that the air film thickness, load capacity, stiffness, load moment, attitude angle and volume flow rate are affected greatly by the angular misalignment.

关键词： angular misalignment static characteristics air journal bearing finite different method

Inter-asperity cavitation for misalignment journal lubrication problem based on mass-conservative algorithm

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第9期14卷 642-656页

作者： Zhen-peng HE Jun-hong ZHANG Zhou-yu LI Lin BA Gui-chang ZHANG Kai-nan WANG Xing LU State Key Laboratory of Engine Tianjin University SAIC Motor Technical Center School of Materials Science and Engineering Tianjin University Civil Aviation University of China

Journal misalignment is common in journal bearings. When severe journal misalignment takes place, it affects nearly all aspects of bearing performance. This paper provided a comprehensive analysis of misaligned journal bearings based on two different mass-conservative models which appropriately took into account film rupture and reformation. The lubrication characteristics and performance parameters including the cavitation zones, pressure distribution, density distribution, oil leakage, load capacity, moment, and attitude angle were compared with the traditional lubrication model. The results showed that cavitation has great effect on bearing performances, especially when the surface roughness is large. Therefore, it is necessary to consider the effects of journal misalignment alongside inter-asperity cavitation theory in the design and analyses of journal bearings.

关键词： misalignment Cavitation Mass-conservation Journal bearing

Research on suppress vibration of rotor misalignment with shear viscous damper

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High Technology Letters 2015年第2期21卷 239-243页

作者：黄秀金 He Lidong Wang Cai Safety Engineering Research Center of the Ministry of Education Beijing University of Chemical Technology

A new type of shear viscous damper for rotating machinery is designed. The new damper with good stability and reliability can inhibit all kinds of frequency multiplication vibration caused by misalignment in the condition of nonstop machine. It analyzes and discusses the use of the shear viscous damper for misalignment vibration response inhibition with a finite element method, and experi ments are extensively carried out with a laboratory test rig. Both the simulation and experimental re suits basically agree well in that, the damper can effectively control the misalignment vibration of the rotor system and improves the stability of the plitude of one time running speed component bration has been basically eliminated. entire rotor system. Experimental results show the am decreases by 30% , and the two time running speed vibration has been basically eliminated.

关键词： shear viscous damper misalignment rotor system vibration control

Dynamic response of large increased pressure wind tunnel rotor-gear coupling system with parallel misalignment

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Journal of Harbin Institute of Technology(New Series) 2008年第1期15卷 71-76页

作者：董国庆崔亚辉王仲仁刘占生沈济全 School of Material Science and Engineering Harbin Institute of Technology School of Energy Science and Engineering Harbin Institute of Technology Chinese Aerodynamics Research Institute of Aeronautics

To study the misalignment of gear coupling, this paper analyzed the distortion of the tooth of gear coupling on the base of gear coupling’s motion under parallel misalignment, and derived the specific expression of additive radial force, which produced by the rotor’ torque. The motion differential equations of the large increased pressure wind tunnel rotor-gear coupling system were derived by the finite element method. Newmark integral method was applied to calculate the dynamic response of the system with parallel misalignment. The numerical results show that: under the effect of additive radial force, the static misalignment can arouse 2X frequency component lateral vibration; the dynamic misalignment can arouse2X,4X,6X multiple frequency components lateral vibration. The 2X frequency component is obvious. The additive radial force of the gear coupling can arouse lateral vibration with even multiple frequency components.

关键词： gear coupling misalignment dynamic response rotor system