Development of a Measurement System for Analyzing Periodic External Forces Acting on Rotating Machineries

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Shota Yabui ◽  
Tsuyoshi Inoue
Keyword(s):  
Measurement System ◽  
Adaptive Algorithm ◽  
Journal Bearing ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Active Magnetic Bearing ◽  
Rotating Shaft ◽  
Rotating System ◽  
External Forces ◽  
Rotating Machineries

In this study, a measurement system is developed to analyze periodic external forces acting on a rotating machinery. The dynamics of a rotating machineries are influenced by various periodic external forces such as unbalanced forces, oil film forces at a journal bearing, and seal contact forces. The characteristics of periodic external forces are dependent on the rotating conditions, rotational speed, and rotating orbit of the rotating shaft. The proposed system employs an active magnetic bearing (AMB), which is implemented using an adaptive feed-forward cancellation (AFC). The use of AFC ensures that the proposed system can realize the desired harmonic orbit assuming actual operations under the periodic external forces. Moreover, AFC can measure the periodic external forces in real-time using an adaptive algorithm. The effectiveness of the proposed system is verified experimentally. Experimental results show that the control system can control the rotating shaft to an accuracy of micrometer order using the implemented AFC. The measurement error of the periodic external forces acting on the rotating system is less than 2%.

Development of Active Magnetic Bearing System Using Adaptive Feedforward Cancellation for Compensation and Analysis of External Forces in Rotating Machinery

2018 ◽  
Author(s):  
Shota Yabui ◽  
Tsuyoshi Inoue
Keyword(s):  
Journal Bearing ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Active Magnetic Bearing ◽  
Rotating Shaft ◽  
Rotating Speed ◽  
External Forces ◽  
Adaptive Feedforward ◽  
Bearing System ◽  
Rotating Machineries

In this research, a rotor system using active magnetic bearing has been proposed to analyze for external forces in rotating machineries. Dynamics of the rotating machineries are influenced from the various external forces such as unbalanced forces, oil film forces at a journal bearing, and seal contact forces. The characteristics of the external forces are dependent on rotating speed and rotating orbit of the rotating shaft. In development the rotating machineries, the analysis of the characteristics of external forces is required under various rotating condition. The proposed system can compensate and analyze for the external forces by using the adaptive feed-forward cancellation (AFC). By using AFC, the proposed system can realize the desired rotating conditions under acting the external forces and analyze the characteristics external forces. The effectiveness of the proposed system has been confirmed experimentally.

A New Approach for Health Monitoring and Detection of Shaft Crack Using an Active Magnetic Actuator During Steady-State Rotor Operation

2007 ◽  
Author(s):  
M. Kasarda ◽  
T. Bash ◽  
D. Quinn ◽  
G. Mani ◽  
D. Inman ◽  
...  
Keyword(s):  
Steady State ◽  
Natural Frequency ◽  
Health Monitoring ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Vibration Monitoring ◽  
Rotating Shaft ◽  
Rotating System ◽  
Rotating Machine ◽  
Input Signals

This work demonstrates the capability of an Active Magnetic Bearing (AMB) to be used as an actuator for interrogating a system by applying multiple forces to a rotating shaft in order to monitor and evaluate the associated responses to these inputs. Similar to modal analysis techniques which apply input signals to static structures in order to monitor responses to those inputs, this approach allows for the measurement of both input and output response in a rotating system for evaluation. However, unlike these techniques, the procedure developed here allows for multiple forms of force inputs to be applied to a rotating structure. This procedure facilitates the development of new improved techniques for diagnosing subtle changes in machinery health or for identifying faults that would potentially go undetected by conventional methods before failure. Although it is expected that this approach can be used in rotors supported in AMBs, the technique developed here uses an AMB on the rotor in conjunction with conventional support bearings. Therefore, this approach has the potential to be used on any rotating machine that can be designed or retrofitted with a single AMB actuator. To demonstrate this approach experimentally, a notched shaft was chosen to represent a shaft crack for identification purposes. Three cases were examined, including a healthy (unnotched) shaft, and three cases of a shaft with a mid-span notch extending to a depth of 10%, 25%, and 40% of shaft diameter, respectively. During testing, excitations up to 1000 Hz were applied via one axis of the AMB actuator to the four rotor cases while the rotor was operating at a steady-state speed of 2400 rpm, and corresponding responses were recorded at the proximity probes. No changes in the 1st or 2nd natural frequencies were detected, but distinct shifts in the 3rd natural frequency were detected from the Frequency Response Function (FRF) data. Since the vast majority of rotating machinery are designed to operate below the 3rd natural frequency, the effect of the notch on the 3rd natural frequency would not have been identified without the application of excitation forces through the AMB actuator. This paper represents an introduction to the new health monitoring approach and results presented here demonstrate the viability of the technique for detecting shaft cracks that might otherwise go undetected in typical steady-state vibration monitoring approaches.

On the Use of Actively Controlled Auxiliary Bearings in Magnetic Bearing Systems

2008 ◽  
Author(s):  
Iain S. Cade ◽  
M. Necip Sahinkaya ◽  
Clifford R. Burrows ◽  
Patrick S. Keogh
Keyword(s):  
Controller Design ◽  
Control Strategies ◽  
Frictional Heating ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Active Magnetic Bearing ◽  
Physical Limit ◽  
Drop Tests ◽  
Auxiliary Bearing ◽  
And Control

Auxiliary bearings are used to prevent rotor/stator contact in active magnetic bearing systems. They are sacrificial components providing a physical limit on the rotor displacement. During rotor/auxiliary bearing contact significant forces normal to the contact zone may occur. Furthermore, rotor slip and rub can lead to localized frictional heating. Linear control strategies may also become ineffective or induce instability due to changes in rotordynamic characteristics during contact periods. This work considers the concept of using actively controlled auxiliary bearings in magnetic bearing systems. Auxiliary bearing controller design is focused on attenuating bearing vibration resulting from contact and reducing the contact forces. Controller optimization is based on the H∞ norm with appropriate weighting functions applied to the error and control signals. The controller is assessed using a simulated rotor/magnetic bearing system. Comparison of the performance of an actively controlled auxiliary bearing is made with that of a resiliently mounted auxiliary bearing. Rotor drop tests, repeated contact tests, and sudden rotor unbalance resulting in trapped contact modes, are considered.

scholarly journals Exploration of NDE Properties of AMB Supported Rotors for Structural Damage Detection

2010 ◽  
Author(s):  
Jerzy T. Sawicki ◽  
Dmitry L. Storozhev ◽  
John D. Lekki
Keyword(s):  
Structural Damage ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Line Detection ◽  
Control Loop ◽  
Structural Damage Detection ◽  
Cracked Rotor ◽  
Rotating Shaft ◽  
On Line ◽  
Combination Frequencies

This paper addresses self-diagnostic properties of AMB (active magnetic bearing) supported rotors for on-line detection of the transverse crack on a rotating shaft. In addition to pure levitation, the rotor supporting bearing also serves as an actuator that transforms current signals additionally injected into the control loop into the superimposed specially selected excitation forces into the suspended rotor. These additional excitations induce combination frequencies in the rotor response, providing unique signatures for the presence of crack. The background of theoretical modeling, experimental and computer simulation results for the AMB supported cracked rotor with self-diagnostic excitation forces are presented and discussed.

Controlling Journal Bearing Instability Using Active Magnetic Bearings

2007 ◽  
Author(s):  
A. El-Shafei ◽  
A. S. Dimitri
Keyword(s):  
Journal Bearing ◽  
Magnetic Bearing ◽  
Journal Bearings ◽  
Active Magnetic Bearing ◽  
Rotating Speed ◽  
Damping Characteristics ◽  
Oil Whip ◽  
Novel Approach ◽  
Oil Whirl ◽  
Load Carrying

Journal Bearings are excellent bearings due to their large load carrying capacity and favorable damping characteristics. However, Journal bearings are known to be prone to instabilities. The oil whirl and oil whip instabilities limit the rotor maximum rotating speed. In this paper, a novel approach is used to control the Journal bearing (JB) instability. An Active Magnetic Bearing (AMB) is used to overcome the JB instability and to increase its range of operation. The concept is quite simple: rather than using the AMB as a load carrying element, the AMB is used as a controller only, resulting in a much smaller and more efficient AMB. The load carrying is done by the Journal bearings, exploiting their excellent load carrying capabilities, and the JB instability is overcome with the AMB. This results in a combined AMB/JB that exploits the advantages of each device, and eliminates the deficiencies of each bearing. Different controllers for the AMB to control the JB instability are examined and compared theoretically and numerically. The possibility of collocating the JB and the AMB is also examined. The results illustrate the effectiveness of the concept.

Dynamic Analysis for the Rotor Drop Process and Its Application to a Vertically Levitated Rotor/Active Magnetic Bearing System

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Yulan Zhao ◽  
Guojun Yang ◽  
Patrick Keogh ◽  
Lei Zhao
Keyword(s):  
High Speed ◽  
Sliding Friction ◽  
Engineering Application ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Active Magnetic Bearing ◽  
Detailed Model ◽  
Vertical Rotor ◽  
Auxiliary Bearing ◽  
Rotor Dynamic

Active magnetic bearings (AMBs) have been utilized widely to support high-speed rotors. However, in the case of AMB failure, emergencies, or overload conditions, the auxiliary bearing is chosen as the backup protector to provide mechanical supports and displacement constraints for the rotor. With lack of support, the auxiliary bearing will catch the dropping rotor. Accordingly, high contact forces and corresponding thermal generation due to mechanical rub are applied on the dynamic contact area. Rapid deterioration may be brought about by excessive dynamic and thermal shocks. Therefore, the auxiliary bearing must be sufficiently robust to guarantee the safety of the AMB system. Many approaches have been put forward in the literature to estimate the rotor dynamic motion, nonetheless most of them focus on the horizontal rotor drop and few consider the inclination around the horizontal plane for the vertical rotor. The main purpose of this paper is to predict the rotor dynamic behavior accurately for the vertical rotor drop case. A detailed model for the vertical rotor drop process with consideration of the rotating inclination around x- and y-axes is proposed in this paper. Additionally, rolling and sliding friction are distinguished in the simulation scenario. This model has been applied to estimate the rotor drop process in a helium circulator system equipped with AMBs for the 10 MW high-temperature gas-cooled reactor (HTR-10). The HTR-10 has been designed and researched by the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University. The auxiliary bearing is utilized to support the rotor in the helium circulator. The validity of this model is verified by the results obtained in this paper as well. This paper also provides suggestions for the further improvement of auxiliary bearing design and engineering application.

Development of Experimental Active Magnetic Bearing Device for Measurement of Mechanical Seal Reaction Force Acting on Rotor

2018 ◽  
Author(s):  
Hiroki Manabe ◽  
Shota Yabui ◽  
Hideyuki Inoue ◽  
Tsuyoshi Inoue
Keyword(s):  
Force Measurement ◽  
Reaction Force ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Mechanical Seal ◽  
Rotating Shaft ◽  
Fluid Force ◽  
Fluid Forces ◽  
Whirling Motion ◽  
Measurement And Evaluation

In turbomachinery, seals are used to prevent fluid leakage. At seal part, rotordynamic fluid force (RD fluid force), which causes whirling motion of rotor, is generated. Under certain conditions, the RD fluid force may contribute to instability of the machine. There are several cases that the whirling is accompanied by eccentricity due to the influence of gravity, or the whirling orbit becomes elliptical due to the influence of the bearing support anisotropy. In these cases, mathematical modeling of the RD fluid forces becomes increasingly complex. As a result, the RD fluid force measurement is more preferable. To improve the measurement and evaluation technology of the RD fluid force, a method to arbitrarily control whirling of the orbit is required. In this paper, RD fluid force measurement by controlling the shape of the orbit using an active magnetic bearing (AMB) is proposed. A contact type mechanical seal is used as a test specimen. When the rotating shaft is whirling, the RD fluid force due to hydrodynamics lubrication and the frictional force due to contact occur on the sliding surface. The resultant force of these forces is taken as the reaction force of mechanical seal and the measurement is performed. The measured reaction force of the mechanical seal is compared with simulation results and the validity of the proposed measurement method is confirmed.

Track-Following Controller Design Using an Active Magnetic Bearing for Measurement of the Rotor Dynamics Coefficient of the Annular Seal

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Shota Yabui ◽  
Hideyuki Inoue ◽  
Tsuyoshi Inoue
Keyword(s):  
Control System ◽  
Controller Design ◽  
Rotor Dynamics ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Active Magnetic Bearing ◽  
Rotating Shaft ◽  
Operating Condition ◽  
Rotating Machine ◽  
Annular Seal

Abstract This study introduces a track-following controller design to measure the rotor dynamics (RD) coefficient of the annular seal using active magnetic bearings. The annular seal is implemented contiguously to prevent leakage of fluid between the rotating shaft and stationary area of a rotating machine. The force caused by the seal at the contact point can cause vibrations, which should be identified for designing rotating machinery. The RD force is coupled with mechanical and fluid dynamics. Moreover, the dynamics depend on the operating conditions of the rotating machine, namely, the rotating speed and orbit of the rotating shaft. This study proposes a control system for the active magnetic bearing to measure the RD force directly at the arbitrary operating condition. The main controller is designed to satisfy a criterion of the frequency characteristics of the rotating system. In addition, the control system employs adaptive feed-forward cancellation (AFC). This can estimate and compensate for the RD force in the control system simultaneously. The experimental results indicate that the control system can achieve an arbitrary operating condition and measure the RD coefficient of the annular seal in real-time. As a result, the RD coefficient is identified based on the equation of motion.

Monitoring and Diagnostics of the Rotating System with an Active Magnetic Bearing

2013 ◽  
Vol 198 ◽  
pp. 547-552
Author(s):  
Małgorzata Gizelska ◽  
Dorota Kozanecka ◽  
Zbigniew Kozanecki
Keyword(s):  
Diagnostic System ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Rotating System ◽  
Automatic Mode ◽  
Actual Operation ◽  
Advanced Information Technology ◽  
Monitoring And Diagnostics ◽  
Proper Operation

In the paper, a concept and selected procedures of the specialized software using advanced information technology for the diagnostic system dedicated for systems of rotating machines with active magnetic bearings will be presented. It is used in the actual operation of the machine, enabling an increase of its reliability. The paper presents some selected results of control of the proper operation of the mechatronic rotating system, carried out in the automatic mode.

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