Nonlinear behaviors analysis of high-speed rotor system supported by aerostatic bearings

2021 ◽  
pp. 107111
Author(s):  
Jianbo Zhang ◽  
Dongjiang Han ◽  
Zhongliang Xie ◽  
Chao Huang ◽  
Zhushi Rao ◽  
...  
Keyword(s):  
High Speed ◽  
Rotor System ◽  
Aerostatic Bearings ◽  
Nonlinear Behaviors

Development and Experimental Performance Verification of a Magneto-Aerostatic Bearing for Cartridge of Dental Handpieces

2012 ◽  
Author(s):  
Guan-Chung Ting ◽  
Kuang-Yuh Huang ◽  
Keng-Ning Chang
Keyword(s):  
High Speed ◽  
Ball Bearings ◽  
Aerostatic Bearing ◽  
Operation Conditions ◽  
Air Inlet ◽  
Efficient Performance ◽  
Aerostatic Bearings ◽  
Repulsive Forces ◽  
Radial Loading ◽  
Air Film

Bearings for high-speed rotors are the key component of dental handpieces. The friction induced by conventional ball bearings restricts its speed and reduces its efficiency. In order to significantly improve the efficiency of dental handpieces, a mini-type cartridge that integrates a turbine and a spindle with radial aerostatic bearings and axial passive magnetic bearings has been ingeniously designed and realized. Around the rotating spindle, there is a high-pressured air film built up by a pair of radial aerostatic bearings, and magnet rings are applied to create repulsive forces to axially support the rotating spindle. The high-pressured air film comes from the specifically designed separable orifice restrictors, which can be easily and precisely manufactured. Frictionless bearing effect can be achieved by aerostatic principle, and the magnetic principle is applied to create large repulsive force against the axial working force. A tri-directional air inlet is designed to reduce radial loading force of a spindle during working. The modularized form of the magneto-aerostatic bearing allows it to be easily assembled and replaced in the very compact space of a mini-type cartridge. Through analytical simulations with fluid-dynamics software (CFD) and experiments, the magneto-aerostatic bearing is optimized to bring out efficient performance in its limited space. The experiments have verified that its noise level is 15dB lower than the conventional cartridge with ball bearings, and its startup air pressure is reduced from 0.4 bar to 0.1 bar. Under the same operation conditions, the newly developed cartridge with magneto-aerostatic bearings creates twice higher speed than that of the conventional one.

Transient Vibration of High-Speed, Lightweight Rotors Due to Sudden Imbalance

1983 ◽  
Vol 105 (3) ◽  
pp. 480-486 ◽  
Author(s):  
M. Sakata ◽  
T. Aiba ◽  
H. Ohnabe
Keyword(s):  
Transient Response ◽  
High Speed ◽  
Rotor System ◽  
Response Analysis ◽  
Transient Vibration ◽  
Flexible Shaft ◽  
Shaft System ◽  
Transient Response Analysis ◽  
Flexible Disk ◽  
Blade Loss

In the field of rotor dynamics, increased attention is being given to the transient response analysis of the rotor, since the effects of impact loading and vibrations of the rotor arising from blade loss can be studied by a time transient solution of the rotor system. As recent trends in rotating machinery have been directed towards lightweight, high-speed flexible rotors, the effect of flexibility on transient response analysis is becoming of increasing importance. In the present paper, a transient vibration analysis is carried out on a flexible-disk/flexible-shaft system or rigid-disk flexible-shaft system subjected to a sudden imbalance that is assumed to represent the effect of blade loss. To solve the basic equation governing a rotating flexible disk the Galerkin’s method is used, and the equation of motion of the rotor system is numerically solved by employing the Runge-Kutta-Gill’s method. Experiments were conducted on a model rotor having a blade loss simulator; the shaft vibrations were also measured. The validity of the anaytical results was demonstrated by comparison with the experimental results.

On the dynamic stability of high-speed gas bearings: stability study and experimental validation

2011 ◽  
Vol 2 (2) ◽  
pp. 342-351
Author(s):  
T. Waumans ◽  
J. Peirs ◽  
J. Reynaerts ◽  
F. Al-Bender
Keyword(s):  
Dynamic Stability ◽  
Stability Problem ◽  
High Speed ◽  
Experimental Validation ◽  
Stability Study ◽  
Gas Bearings ◽  
Aerostatic Bearings ◽  
Bearing Dynamics ◽  
Wide Operating ◽  
Operating Temperature Range

For high-speed applications, gas lubricated bearings offer very specific advantages over other,more conventional bearing technologies: a clean and oil-free solution, virtually wear-free operation, lowfrictional losses, wide operating temperature range, etc. However, the principal drawback involved in theapplication of high-speed gas bearings concerns the dynamic stability problem. Successful applicationtherefore requires control of the rotor-bearing dynamics so as to avoid instabilities.After a detailed study of the dynamic stability problem and the formulation of a convenient stability criterium,a brief overview is given of the currently existing bearing types and configurations for improving the stability.In addition, three strategies are introduced: (i) optimal design of plain aerostatic bearings; (ii) modification ofthe bearing geometry to counteract the destabilising effects in the gas film; and (iii) introduction of dampingexternal to the gas film as to compensate for the destabilising effects.These strategies are worked out into detail leading to the formulation of a series of design rules. Theireffectiveness is validated experimentally at a miniature scale. In recent experiments a rotational speed of1.2 million rpm has been achieved with a 6 mm rotor on aerodynamic journal bearings, leading to a recordDN-number of 7.2 million.

Internal Rotor Friction Induced Instability in High-Speed Rotating Machinery

1993 ◽  
Author(s):  
James F. Walton ◽  
Michael R. Martin
Keyword(s):  
Internal Friction ◽  
Natural Frequency ◽  
High Speed ◽  
Critical Speed ◽  
Rotating Machinery ◽  
Rotor System ◽  
Analytical Models ◽  
Interference Fit ◽  
Internal Rotor

Abstract Results of a program to investigate internal rotor friction destabilizing effects are presented. Internal-friction-producing joints were shown to excite the rotor system first natural frequency, when operating either below or above the first critical speed. The analytical models used to predict the subsynchronous instability were also confirmed. The axial spline joint demonstrated the most severe subsynchronous instability. The interference fit joint also caused subsynchronous vibrations at the first natural frequency but these were bounded and generally smaller than the synchronous vibrations. Comparison of data from the two test joints showed that supersynchronous vibration amplitudes at the first natural frequency were generally larger for the interference fit joint than for the axial spline joint. The effects of changes in imbalance levels and side loads were not distinguishable during testing because amplitude-limiting bumpers were required to restrict orbits.

scholarly journals Rotor dynamic experimental investigation of an ultra-high-speed permanent magnet synchronous motor supported on a three-pad bidirectional gas foil bearing

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987536
Author(s):  
Wenjie Cheng ◽  
Zhikai Deng ◽  
Ling Xiao ◽  
Bin Zhong ◽  
Wenbo Duan
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Permanent Magnet Synchronous Motor ◽  
Synchronous Motor ◽  
Rotor System ◽  
Permanent Magnet Motors ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Ultra High Speed ◽  
Rotor Dynamic

With a 10-kW, 120,000-r/min, ultra-high-speed permanent magnet synchronous motor taken as a prototype, experimental research is conducted on the rotor dynamic behaviours of a three-pad bidirectional gas foil bearing high-speed motor rotor system. Load-carrying properties of the three-pad bidirectional gas foil bearing are analysed, and natural frequencies of conical and parallel whirling modes of the elastically supported rotor are calculated based on an appropriate simplification to the stiffness and damping coefficients of the gas foil bearings. The prototype passes through a 90,000-r/min coast-down experiment. Experiments show that there are violent subsynchronous whirling motions that are evoked by the gas foil bearing–rotor system itself. The cause of shaft orbit drift is analysed, and the corresponding solution is put forward. The theoretical analysis and experimental results can offer a useful reference to the bearing–rotor system design of ultra-high-speed permanent magnet motors and its subsequent dynamic analysis.

scholarly journals Dynamic Characteristics of Gear Coupling and Rotor System in Transmission Process Considering Misalignment and Tooth Contact Analysis

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1336
Author(s):  
Wei Fan ◽  
Hong Lu ◽  
Yongquan Zhang ◽  
Xiangang Su
Keyword(s):  
Finite Element ◽  
Dynamic Model ◽  
Calculation Method ◽  
High Speed ◽  
Low Frequency ◽  
Rotor System ◽  
Integral Approach ◽  
Time Frequency ◽  
Low Frequency Vibration ◽  
Mass Eccentricity

The dynamic vibration of the gear coupling-rotor system (GCRS) caused by misalignment is an important factor of low frequency vibration and noise radiation of the naval marine. The axial misalignment of gear coupling is inevitable owing to mass eccentricity, and is unconstrained in axial direction at high-speed operation. Therefore, the dynamic model of GCRS is proposed, considering gear-coupling misalignment and contact force in this paper. The whole motion differential equation of GCRS is established based on the finite element method. Moreover, the numerical calculation method of meshing force, considering the uniform distribution load on contact surface, is presented, and the mathematical predictive time–frequency characteristics are analyzed by the Newmark stepwise integral approach. Finally, a reduced-scale application of the propulsion shaft system is utilized to validate the effectiveness of the proposed dynamic model. For the sensibility to low-frequency vibration, the natural frequencies and vibration modes of GCRS are analyzed through the processing and analysis of acceleration signal. The experimental dynamic response and main components of vibration are respectively consistent with mathematical results, which demonstrate the effectiveness of the proposed dynamic model of GCRS with misalignment. Furthermore, it also shows that the proposed finite element analysis and calculation method are suitable for complex shafting, providing a novel thought for dynamic analysis of the propeller–shaft–hull coupled system of marine.

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