PhD, Tsinghua University, Materials Science and Engineering, 2011
B.S., Tsinghua University, Mechanical Engineering and Automation, 2005
01/2018-present, Associate Professor, Division of Magnetic Bearing Technology, INET
04/2011-12/2017, Assistant Professor, Division of Magnetic Bearing Technology, INET
Areas of Research Interests/ Research Projects
Dr. Liu’s research interests are in the areas of Active Magnetic Bearing (AMB) structure design, electromagnetic field analysis, rotor dynamics, auxiliary bearing for AMB, helium gas discharge, etc..
Active Magnetic Bearing (AMB) structure design
The Active Magnetic Bearing (AMB) suspends the rotor by the electromagnetic force. It has advantages of no friction, no lubrication, high speed and controllability. Different AMB structures are designed to meet different industrial requirements. Some novel AMBs are being researched, such as homopolar radial bearing, electromagnetic-permanent magnet hybrid bearing, laminated axial bearing and so on.
Electromagnetic field analysis
The electromagnetic field of the AMB is analyzed to calculate the electromagnetic force, the eddy current loss, the hysteresis loss and so on. The measurement of electromagnetic properties of materials is an important basis of the analysis. Professional measuring equipment and electromagnetic field finite element analysis software are used.
The speed of the AMB rotor is usually very high, sometimes higher than the first bending critical speed. So the calculation of the rotor modal is important for the AMB design. The AMB rotor is complex with interference fit laminations, and it’s difficult to calculate its critical speed and other modal characteristics. The effects of the interference parameters on the critical speed and on the other modal characteristics are studied.
Auxiliary bearing will temporarily support the rotor during assembly, overload or power failure. It is an important guarantee for the reliability of the AMB. Rolling bearing is usually used as the auxiliary bearing. It will work under atypical conditions, including rapid acceleration, over speed and heavy load. The impact force on the auxiliary bearing when the rotor drops during power failure, the life of the auxiliary bearing, the motion of the rotor, and the novel auxiliary bearing are studied.
Helium gas discharge
The High Temperature gas cooled Reactor (HTR) use helium gas as coolant. Some electrical instruments used in HTR, including AMB, work in high temperature and high pressure helium gas. The insulation of the helium gas is much weaker than the air under the same conditions. So the study of the helium gas discharge is very important for the insulation design in HTR. The special experimental equipment is stablished, and the breakdown voltage of high temperature (180℃) and high pressure (7MPa) helium gas in both uniform and non-uniform electric field is studied.
Study on the performance of gas-solid composite insulation structure using high temperature and high pressure helium gas as gas medium
Research and Fault Diagnosis of Auxiliary Bearing with no Lubricant on the System of Active Magnetic Bearing
Research on electromagnetic bearing technology for main helium fan
You Qi, Mo Ni, Liu Xingnan, Luo Huan, Shi Zhengang*. Experiments on helium breakdown at high pressure and temperature in uniform field and its simulation using COMSOL Multiphysics and FD-FCT. Annals of Nuclear Energy, 2020 (141), 107351.
Liu Xingnan, Zhou Yan, Yan Xunshi, Zhao Jingjing, Shi Zhengang*, Chen Jianqiang, Zhao Yulan, Yang Guojun*. Experimental study on the novel rolling-sliding integrated auxiliary bearing in active magnetic bearing during rotor drop. Annals of Nuclear Energy, 2019 (136), 107044.
Liu Xingnan, Shi Zhengang, Mo Ni, Zhao Jingjing, and Yang Guojun*. Calculation and experiment of electromagnetic force of the axial AMB used in HTR-PM main helium blower prototype and its dual material selection method. ACES Journal, 2019 (34), 4, 584-590.
Zhao Yulan, Liu Xingnan, Yang Guojun*, Shi Zhengang, Zhao Lei. Dynamic Analysis for the Rotor Drop Process and Its Application to a Horizontal Rotor-Active Magnetic Bearing System in Helium Gas. Journal of Tribology-Transactions of the ASME, 2018, 140(4): SC041704.
Liu Xingnan, Shi Zhengang, Yang Guojun*, Yan Xunshi. Experimental study on breakdown voltage of high pressure and high temperature helium gas between parallel electrodes. Annals of Nuclear Energy, 2017 (110), 1224–1231.
Liu Xingnan, Shi Zhengang, Yang Guojun*, Yan Xunshi. Theoretical research about the dynamics of a rotor with a decreasing length suspended by active magnetic bearing, Proceedings, ICONE 25nd, 2017, Shanghai China.
Liu Xingnan, Shi Zhengang, Yang Guojun, Zhao Jingjing. A homopolor radial electromagnetic bearing: China, ZL201710886271.5. 2017-9-26.
Liu Xingnan, Yu Suyuan, Yang Guojun, Zhou Yan, Shi Zhengang. An axial magnetic bearing with an annular heat dissipation structure: China, ZL201310228470.9. 2016-1-20.
Liu Xingnan, Yu Suyuan, Yang Guojun, Zhao Jingjing, Shi Zhengang. An axial magnetic bearing base with heat dissipation fins and an axial magnetic bearing with such base: China, ZL201310228979.3. 2015-10-28.