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1
Choy, F. K., J. Padovan i Y. F. Ruan. "Coupling of Rotor-Gear-Casing Vibrations During Extreme Operating Events". Journal of Pressure Vessel Technology 114, nr 4 (1.11.1992): 464–71. http://dx.doi.org/10.1115/1.2929256.
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During extreme operating environments (i.e., seismic events, base motion-induced vibrations, etc.), the coupled vibrations developed between the rotors, bearings, gears and enclosing structure of gear-driven rotating equipment can be quite substantial. Generally, such large vibrational amplitudes may lead to failures in both the rotor-gearing system and/or the casing structure. This paper simulates the dynamic behavior of rotor-bearing-gear system resulting from motion of the enclosed structure. The modal synthesis approach is used in this study to synthesize the dynamics of the rotor systems with the vibrations of their casing structure in modal coordinates. Modal characteristics of the rotor-bearing-gear systems are evaluated using the matrix transfer technique, while the modal parameters for the casing structure are developed through a finite element model using NASTRAN. The modal accelerations calculated are integrated through a numerical algorithm to generate modal transient vibration analysis. Vibration results are examined in both time and frequency domains to develop representations for the coupled dynamics generated during extreme operating conditions. Typical three-rotor bull gear-driven power plant equipment (compressors, pumps, etc.) is used as an example to demonstrate the procedure developed.
2
Wang, Shuang, Xin Ma, Yongcun Guo, Shousuo Sun i Zeyong Hu. "Vibrational coupling mechanism and experimental study of rotor system with double-disk magnetic coupler". Advances in Mechanical Engineering 15, nr 3 (marzec 2023): 168781322311629. http://dx.doi.org/10.1177/16878132231162954.
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At present, the vibrational coupling mechanism of the rotor system with a double-disk magnetic coupler has not been sufficiently studied. Based on the mechanical impedance theory, the patterns of structural mass and stiffness distribution were quantitatively described, to establish the model for the vibrational coupling mechanism. Methods were proposed to determine the vibrational coupling point and to simulate the transient response to the interacting excitations, so as to analyze the potential vibrational coupling point and the dynamic response characteristics. Then, the Campbell diagram of the shared support-dual rotor system was combined with the mechanical impedance characteristics of the shared support. As a result, it was found that although the base vibration of the shared support was significantly amplified, the single-axis trajectory showed that both the output and input rotors were synchronized with the forward vortex motion, with almost no coupling between them. A double-disk magnetic coupler test bench with a rated power of 55 kW was designed to verify the experiments. The results showed that the vibration displacement occurred in a periodic variation pattern. Moreover, the maximum errors between the theoretical, simulated, and experimental values of the vibration displacement at different input speeds were less than 5%. The experiments verified the validity of the model for the vibrational coupling mechanism and the simulation of the transient response to the interacting excitation. The results of the study could be used as a basis for calculating the vibration of the rotor system with a double-disk magnetic coupler.
3
Kurakin, Anton. "EFFECT OF FRICTION ON VIBRATIONAL CHARACTERISTICS OF ROTOR SYSTEM DURING ROTOR-STATOR INTERACTION". Perm National Research Polytechnic University Aerospace Engineering Bulletin, nr 61 (2020): 22–31. http://dx.doi.org/10.15593/2224-9982/2020.61.03.
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Systems operation which include rotating elements in certain cases is associated with occurrence of contact between the rotating parts (rotor) and the stationary parts (stator). There were cases then rotor-stator interaction led to damage or to complete unit destruction. For this reason, rotor-stator interaction is one of the main problem of rotor systems exploitation. The main aim of the work is to gather detail data about effect of friction on vibrational characteristics of rotor system during rotor-stator interaction. In this article the experimental investigation method and experimental investigation of dynamic behavior of rotor during rotor-stator interaction is presented. The analysis of experimental data obtained during interaction between steel rotor and stator made of aluminum, bronze and PTFE is presented. All results with rotor-stator contact and without were compared by using Campbell diagrams, orbits and frequency responses. Analysis of experimental data shows that friction has strong effect on vibrational characteristics of rotor system during rotor-stator interaction. According to friction ratio three kinds of vibrational characteristics of rotor system are distinguished: forward slipping if friction coefficient is small, backward rolling if friction coefficient is big, vibratory impact motion if friction coefficient has intermediate value. Created experimental method and gathered data about rotor dynamics during rotor-stator contact can be used for verification and tuning of mathematical models.
4
Muszynska, Agnes. "Vibrational Diagnostics of Rotating Machinery Malfunctions". International Journal of Rotating Machinery 1, nr 3-4 (1995): 237–66. http://dx.doi.org/10.1155/s1023621x95000108.
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This paper outlines rotating machinery malfunction diagnostics using vibration data in correlation with operational process data. The advantages of vibration monitoring systems as a part of preventive/predictive maintenance programs are emphasized. After presenting basic principles of machinery diagnostics, several specific malfunction symptoms supported by simple mathematical models are given. These malfunctions include unbalance, excessive radial load, rotor-to-stator rubbing, fluid-induced vibrations, loose stationary and rotating parts, coupled torsional/lateral vibration excitation, and rotor cracking. The experimental results and actual field data illustrate the rotor vibration responses for individual malfunctions. Application of synchronous and nonsynchronous perturbation testing used for identification of basic dynamic characteristics of rotors is presented. Future advancements in vibration monitoring and diagnostics of rotating machinery health are discussed. In the Appendix, basic instrumentation for machine monitoring is outlined.
5
Sinou, Jean-Jacques. "Damage Detection in a Rotor Dynamic System by Monitoring Nonlinear Vibrations and Antiresonances of Higher Orders". Applied Sciences 12, nr 23 (22.11.2022): 11904. http://dx.doi.org/10.3390/app122311904.
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Since rotor systems are very sensitive and vulnerable to transverse crack, early detection of damage is of paramount importance and essential for rotating machinery. Therefore, one of the main issues is to identify robust characteristics of the rotor vibration response that can be directly attributed to the presence of a transverse crack in a rotating shaft, preferably when the crack is small enough, in order to avoid catastrophic failures of rotating machines. This study investigates the potential links between the nonlinear vibrations and the locations of higher-order antiresonances and structural modifications due to the presence of a breathing crack in rotor systems. Using the proposed numerical results on the evolution of the nonlinear responses of a cracked rotor system, it was observed that a robust diagnostic of the presence of slight damage can be conducted by tracking nonlinear vibrational measurements, with particular attention to the antiresonance behavior of higher orders. These observations can easily serve as target observations for the monitoring system and for identifying the positions of damage at an early stage.
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Ma, Yingqun, Qingjun Zhao, Kai Zhang, Meng Xu i Wei Zhao. "Effects of mount positions on vibrational energy flow transmission characteristics in aero-engine casing structures". Journal of Low Frequency Noise, Vibration and Active Control 39, nr 2 (17.05.2019): 313–26. http://dx.doi.org/10.1177/1461348419845506.
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The main goal of the study is to apply the structural intensity method to analyze the effects of positions of the main-mount and the sub-mount on the vibrational energy flow transmission characteristics in aero-engine casing structures, so as to attenuate the vibration of the casing and the whole aero-engine. Structural intensity method, indicating magnitude and direction of the vibrational energy flow, is a powerful tool to study vibration problems from the perspective of energy. In this paper, a casing-support-rotor coupling model subjected to the rotor unbalanced forces is established by the finite element method. Formulations of the structural intensity of a shell element and the structural intensity streamline are given. A simulation system consisting of the finite element tool and the in-house program is developed to carry out forced vibration analysis and structural intensity calculation. The structural intensity field of the casing is visualized in the forms of vector diagram and streamline representation. The vibrational energy flow behaviors of the casing at the rotor design rotating speed are analyzed, and the vibrational energy flow transmission characteristics of the casing with different axial positions of the main-mount and the sub-mount are investigated. Moreover, some measures to attenuate the vibration of the casing are obtained from the numerical results, and their effectiveness is verified in the frequency domain and the time domain. The results shed new light on the effects of the mount positions on the vibration energy transmission behaviors of the casing structure. The structural intensity method is a more advanced tool for solving vibration problems in engineering. Furthermore, it may provide some guidance for the vibration attenuation of the casing and the whole aero-engine.
7
Baher, Karrar, Qasim A. Atiyah i Imad A. Abdulsahib. "Vibration Characteristics of the Bearing Rotor Shaft". Al-Nahrain Journal for Engineering Sciences 25, nr 1 (3.04.2022): 49–54. http://dx.doi.org/10.29194/njes.25010049.
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In this work, the vibrations in the rotor-bearing system are studied experimentally and theoretically using ANSYS Workbench 2020 R1 software to compute the natural frequencies and mode shapes. In the experimental part, the LABVIEW software was used to examine the signal of the frequency domain values obtained from the accelerometer sensors, based on Fast Fourier Transform (FFT) technology and dynamic response spectrum. in the theoretical part, the natural frequencies are determined based on the finite element method for analyzing the system and knowing its behavior and vibration response level. The results showed that the level of vibration becomes higher at high rotational speeds, and it becomes large when the distances between the bearings are large, according to the bearing position and type used in the system. in this work can be concluded, the system is usually affected by the dynamic response around it and is difficult to separate from it, and the vibrations in the system can be controlled by adding an external damping source, which gives the system more stable. A system operating at high speeds can give a large vibration and an unbalanced response.
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Golubkov, V. A., A. U. Gulevitskiy, A. A. Ovodenko, V. F. Shishlakov i A. S. Smirnova. "Structural analysis of vibrational characteristics of rotor systems". Journal of Physics: Conference Series 1515 (kwiecień 2020): 022088. http://dx.doi.org/10.1088/1742-6596/1515/2/022088.
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Keogh, P. S., M. O. T. Cole i C. R. Burrows. "Multi-State Transient Rotor Vibration Control Using Sampled Harmonics". Journal of Vibration and Acoustics 124, nr 2 (26.03.2002): 186–97. http://dx.doi.org/10.1115/1.1448321.
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A technique is introduced to achieve transient vibration attenuation in a multi-input, multi-output flexible rotor/magnetic bearing system. The strategy employs feedback control of measured harmonic components of rotor vibration. Whereas previous harmonic controllers have been based only on steady state vibration characteristics, the new controller also incorporates the transient dynamics. The controller may still be designed from measured data and is determined from target transient vibrational responses arising from step changes in particular disturbances. Account is taken of delays arising from evaluation of harmonic components. Furthermore, stability boundaries for the controller are shown to have significant tolerance to measurement error. The controller is validated experimentally in a flexible rotor/magnetic bearing system and mass loss tests are used to demonstrate rapid decrease in vibration levels with near elimination of transient overshoot.
10
Bartlett, H., i R. Whalley. "Distributed rotor dynamics". Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 212, nr 4 (1.06.1998): 249–65. http://dx.doi.org/10.1243/0959651981539442.
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The modelling, simulation and analysis of powered rotors with ‘long’ thin shells is investigated. General results enabling the prediction of the torsional vibrational signature of high-speed assemblies under acceleration or braking conditions are outlined. It is demonstrated that simulated response characteristics can be easily obtained and the effect of varying the rotor geometry can be routinely accommodated. Finally, a rotor for a high-speed paper manufacturing unit is investigated and the torsional behaviour of the assembly is computed. The volatile transient conditions presented are commented upon.
11
Hou, Shengliang, Lei Hou, Shiwei Dun, Yufeng Cai, Yang Yang i Yushu Chen. "Vibration Characteristics of a Dual-Rotor System with Non-Concentricity". Machines 9, nr 11 (26.10.2021): 251. http://dx.doi.org/10.3390/machines9110251.
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A finite element model of an aero-engine dual-rotor system with intermediate bearing supported by six bearings is set up. Three modes of non-concentricity caused by the assembly process are defined, namely parallel non-concentricity, front deflection angle non-concentricity and rear deflection angle non-concentricity. The influence of the non-concentricity on the vibration characteristics of the dual-rotor system is investigated in detail. The results show that the parallel non-concentricity and the front deflection angle non-concentricity have a significant influence on the bending vibration modals of the high-pressure rotor and the low-pressure rotor, but have little influence on the local vibration modals of the rotors. With the increase in the magnitude of the non-concentricity, the natural frequencies of the bending modals decrease continuously, and the mode shapes of bending modals and that of local modals may be interchanged, leading to the emergence of bending modals in advance. Therefore, the key parameters to be controlled in the assembly process are the parallel non-concentricity and the front deflection angle non-concentricity. In order to prevent the bending modal of the dual-rotor system from appearing in advance, it is necessary to control the parallel non-concentricity within 2 mm and the front deflection angle non-concentricity amount within 0.18°.
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Zhao, Zhiming, Feng Ji, Yongsheng Guan i Xiaoyang Yuan. "Vibration and critical characteristics of the tilting pads journal bearing-rotor system". Industrial Lubrication and Tribology 71, nr 2 (11.03.2019): 295–300. http://dx.doi.org/10.1108/ilt-03-2018-0112.
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Purpose High power rotating machinery requires large diameter bearings that can perform under extreme conditions. Vibrations and critical speeds of rotor supported by tilting pad journal bearing (TPJBs) exceeding their design limits may cause unit failure. This paper aims to investigate the experimental technique for large diameter bearings. Design/methodology/approach To obtain the experimental support for rotor-bearing system design, an experiment focusing on vibration monitoring is given. The sensors arrangement, monitoring system and critical speed identification method are provided. Findings By using test bench in factory unit, a large amount of vibrations data of different working situations is obtained. In addition, a method named non-excitation identification for critical speed is proposed. The critical speed of rotor identified through vibration data is given. The theoretical calculation results are also presented. Originality/value The basis for rotor-bearing system design can be obtained through comparisons between the experimental results and the theoretical calculation data.
13
Karri, Seshendra Kumar Venkat, i Sree Krishna Sundara Siva Rao Bollapragada. "Influence of lateral vibrations on the whirling characteristics of gear-pinion rotor system". Journal of Vibration and Control 18, nr 11 (19.10.2011): 1624–30. http://dx.doi.org/10.1177/1077546311423064.
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The proposed work presents a methodology to analyze the influence of lateral vibrations on the whirling characteristics of a rotor-bearing system. A complex variable approach, which is proposed for the analysis of a single rotor system, is very powerful for this purpose. The approach is expanded to the analysis of a combined rotor system to apply it to the gear system analysis. The bearing stiffness and shaft flexibility of the geared rotor system are taken into account in two ways. With regard to the rotor effect, the frequency response functions are obtained for both torsional motions and coupled lateral-torsional motions. By obtaining the differences in the frequency responses of both the models, the effect of neglecting rotor effects in gear dynamics simulation is studied. The lateral stiffness of the system, which reflects the shaft and bearing stiffness, is considered to make a strong lateral and torsional motion coupling. It is shown that the lateral vibrations have considerable effect when the natural frequencies of the lateral vibration and torsional vibration are close to each other, which is expected. The effect of lateral-torsional coupling on gear dynamics is discussed based on the response of the system.
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Idris, Muhammad, Zakie Anugia i Donny Mustika. "DEVELOPMENT OF FINITE ELEMENT ANALYSIS PROGRAM FOR ROTORDYNAMIC PREDICTION OF SINGLE AND MULTI DISK ROTOR MODEL". Indonesian Journal of Engineering and Science 3, nr 3 (1.11.2022): 001–13. http://dx.doi.org/10.51630/ijes.v3i3.61.
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The rotating equipment is a crucial part of system performance reliability. Vibration, as a characteristic of an oscillating body, is a fundamental parameter to determine the dynamic behaviour of the rotor system. The dynamic characteristics include natural frequency, critical speed, mode shape, and vibration response. This paper discussed the application of rotordynamics analysis as a tool to numerically predict the dynamic behaviour of a rotor system. The aim is to determine a rotor system's natural frequency and critical speed by a finite element analysis (FEA) program. The selected method is validated using various analytical methods from other references with small discrepancies in the result. The calculation of FEA using the computational program; they applied the developed program to describe the dynamic characteristic of single and multi-disk rotors. The developed works provided comprehensive results about a rotor system's natural frequency, mode shape, and critical speed and predicted the vibration response due to unbalance. However, other types of rotors, such as coaxial dual rotors, can be further investigated to make the program capable of the general purpose of the rotor. Validation with the real case problem could be an interesting investigation to satisfy the result of developed works.
15
Sinou, J. J., L. Nechak i S. Besset. "Kriging Metamodeling in Rotordynamics: Application for Predicting Critical Speeds and Vibrations of a Flexible Rotor". Complexity 2018 (2018): 1–26. http://dx.doi.org/10.1155/2018/1264619.
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Rotating machinery produces vibrations depending upon the design of the rotor systems as well as any faults or uncertainties in the machine that can increase the vibrations of such systems. This study illustrates the effectiveness of using surrogate modeling based on kriging in order to predict the vibrational behavior (i.e., the critical speeds and the vibration amplitudes) of a complex flexible rotor in the presence of uncertainties. The basic idea of kriging is to predict unknown values of a function by using a small size set of known data. The kriging estimation is based on a weighted average of the known values of the function in the neighborhood of the point for which the value of the function has to be calculated. The crucial dependence of a kriging predictor versus the correlation functions and different orders will be illustrated. This paper also shows that reducing the number of samples required to have predictive models can be achieved by performing an initial understanding of the mechanical system of interest and by considering certain characteristics directly deriving from the physics of the problem studied.
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Kosushkin, K. G., B. S. Kritsky i R. M. Mirgazov. "Computational studies of the rotors aerodynamic characteristics of multirotor drones". Civil Aviation High Technologies 24, nr 5 (1.11.2021): 60–75. http://dx.doi.org/10.26467/2079-0619-2021-24-5-60-75.
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The article presents the results of computational studies of aerodynamic characteristics for unmanned lift-generating multi-rotor drones of various configurations. The distinctive features of rotors flow were characterized. The rotor interaction was evaluated. The computations were based on the nonlinear rotor blade vortex theory in a non-stationary arrangement. The combinations of four, eight (four coaxial) and fourteen two-bladed rotors at velocity V = 100, 150, 200 km/h were considered. Semi-empirical methods were employed to select the rotor angles of attack, rotation speed, blade installation angles and geometric parameters at the given take-off weight for each combination of rotors and flight airspeed. The computations showed that for a four-rotor lift-generating design (quad-rotor), two rotors installed downstream, depending on the velocity due to the mutual effect, have values of the thrust coefficients ≈10...20% less than those of the rotors located upstream. For a coaxial quad-copter, the effect of the upper front rotor on the upper rear rotor is similar to the effect of the front rotors on the rear ones in a four-rotor lift-generating design. The effect of the upper front rotor on the lower rear rotor does not vary in terms of the average thrust value, and variations are only local in nature. The interaction of other rotors is identical to that of the four-rotor version. A fourteen-rotor lift-generating multi-rotor drone has a complex flow pattern, which generates deviance in the thrust coefficients variation with respect to time. Depending on the mode and rotors location, the average rotor thrust coefficient can vary approximately twice. The computations showed that with the similar geometric parameters and kinematics characteristics, rotors thrust is substantially subject to variation, which causes destabilizing moments to a significant degree without additional control input. Thrust pulsations and, respectively, vibrations grow in intensity as the flight airspeed increases. Probably, the right choice of the rotor configuration and the automatic control system can counterbalance thrust surge by so-called "phasing", i.e. selecting an initial azimuth angle for each rotor.
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Shevchenko, S., O. Shevchenko i S. Vynnychuk. "Mathematical Modelling of Dynamic System Rotor-Groove Seals for the Purposes of Increasing the Vibration Reliability of NPP Pumps". Nuclear and Radiation Safety, nr 1(89) (19.03.2021): 80–87. http://dx.doi.org/10.32918/nrs.2021.1(89).09.
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Groove seals are considered as hydrostatic bearings capable of effectively damping rotor vibrations. In order to determine the dynamic characteristics, a model of the rotor-groove seals system is considered. The radial forces and moments in groove seals had been estimated. Expressions of joint radial-angular rotor vibrations in groove seals had been obtained. Formulas had been proposed for constructing amplitude and phase frequency characteristics. An example of calculating the dynamic characteristics of a centrifugal machine rotor model is presented. The directions of increasing the vibration reliability of NPP pumping equipment by purposefully increasing the rigidity of groove seals are determined.
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Sha, Yun Dong, Feng Tong Zhao i Jia Han. "Investigation into Noise Frequency Spectrum Characteristics Corresponding to Blade Nonsynchronous Vibration in Multi-Stage Axial Compressor". Advanced Engineering Forum 2-3 (grudzień 2011): 870–75. http://dx.doi.org/10.4028/www.scientific.net/aef.2-3.870.
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Unsteady flow phenomenon occurs in a multi-stage axial compressor. The unsteady flow not only has significant influence on the performance of compressor and the stability of flow, but also can be an excitation source inducing Nonsynchronous vibration (NSV) of rotor blade. NSV is an aeroelastic phenomenon where the rotor blades vibrate at nonintegral multiples of the shaft rotational frequencies in operating regimes where classical flutter is not known to occur. Recently, more and more scholars pay attention to Rotating instabilities (RIs) as one of the unsteady flow phenomenon. RIs have been observed in axial flow fans and centrifugal compressors as well as in low-speed and high-speed axial compressors. They are responsible for the excitation of high amplitude rotor blade vibrations and noise generation. This research aims at revealing the relationships among the unsteady flow behaviors, characteristics of inner sound field and propagation, the vibration of rotor blade in multi-stage axial compressor. The noise in compressor and the vibration of rotor blade have been measured on a high pressure compressor rig testing. The transducer system is connected to the interior casing wall through the acoustic waveguide pipes. The noise is measured by 1/4 inch condenser microphones in different operating of the compressor. The time-domain wave of noise acquired at different work status of the compressor is transformed into frequency spectrum by Fast Fourier Transform (FFT) to investigate characteristics of sound field in multi-stage axial compressor. And the emphasis is focused on the frequency characteristics of the noise corresponding to blade nonsynchronous vibration. It is found that the vibration amplitude of the rotor blade suddenly increases in a pre-arranged structure adjustment and specific rotating speed, and noise signal with special frequency structures appears simultaneously. High amplitude levels of blade vibration have occurred on the first rotor of a multi-stage high pressure compressor. The frequencies are not in resonance with harmonics of the rotor speed. The frequency analysis show that the noise has a special frequency structures with combination of the appeared characteristic frequency and the blade pass frequency of rotor blade (BPF). Because the similarities between the frequency combination and the specific frequency structure of the fluctuating pressure when the rotating instability (RI) appears in the axial compressor have been identified, the acting mechanism of rotating instability may exist in this compressor, i.e. the vibrational excitation to the rotor blade may be aerodynamically caused and associated with a rotating flow instability in the compressor.
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Liu, Jing, Yuchen An, Wanli Fancheng, Changke Tang i Lixin Xu. "A dynamic model considering the time-varying friction moment of a flexible rotor system". Engineering Computations 40, nr 5 (12.07.2023): 1128–46. http://dx.doi.org/10.1108/ec-12-2021-0707.
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PurposeBearing friction moments are important factors that affect the vibrations of rotor systems. The bearing friction moments are related to the dimension parameters, lubrication conditions and manufacturing errors of support bearings. This work studies the effects of the bearing friction moments on the vibrations of rotor systems.Design/methodology/approachThe rotor is separated into several shaft elements for formulating a flexible rotor. The time-varying friction moment (TFM) is affected by the time-varying contact loads. The vibrations of FRS from the TFM and Palmgren's friction moment (PFM) calculation methods are compared. Moreover, the effects of the rotor offset and radial clearance on the frequency-amplitude characteristics of FRS are studied.FindingsThe TFM method is more consistent with the actual operation mechanisms. The rotor offset and radial clearance can significantly affect the nonlinear vibrations of FRS. This work provides a new reference and research method for the vibration analysis of rotor systems considering the friction effects.Originality/valueThe elastohydrodynamic lubrication (EHL), elastic hysteresis and differential sliding are considered. A flexible rotor system (FRS) dynamic model considering the TFM is proposed. The vibrations of FRS from the TFM calculation method and empirical calculation formula are compared. The effects of the rotor offset and radial clearance on the frequency–amplitude characteristics of FRS are studied.
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Zhang, Hongxian, Liangpei Huang, Xuejun Li, Lingli Jiang, Dalian Yang, Fanyu Zhang i Jingjing Miao. "Spectrum Analysis of a Coaxial Dual-Rotor System with Coupling Misalignment". Shock and Vibration 2020 (10.07.2020): 1–19. http://dx.doi.org/10.1155/2020/5856341.
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The finite element model of a dual-rotor system was established by Timoshenko beam element. The dual-rotor system is a coaxial rotor whose supporting structure is similar to that of an aero-engine rotor system. The inner rotor is supported by three bearings, which makes it a redundantly supported rotor. The outer rotor connects the inner rotor by an intershaft bearing. The spectrum characteristics of the dual-rotor system under unbalanced excitation and misalignment excitation were analysed in order to study the influence of coupling misalignment of the inner rotor on the spectral characteristics of the rotor system. The results indicate that the vibration caused by the misaligned coupling of the inner rotor will be transmitted to the outer rotor through the intershaft bearing. Multiple harmonic frequency components, mainly 1x and 2x, will be excited by the coupling misalignment. The amplitudes of all harmonic frequencies increase with the misalignment in both the inner and outer rotors. The vibration level of the outer rotor affected by the misalignment is lower than that of the inner rotor because it is far from the misaligned coupling. Harmonic resonance occurs when any harmonic frequencies of the misalignment response coincide with a natural frequency of the system. In order to verify the theoretical model, experiments are performed on a test rig. Both the experimental and simulation results are in good accordance with each other.
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Fan, Ye Sen, San Min Wang i Zhen Yang. "Dynamic Characteristics of the Coupled System of the High Pressure Rotor and the Radial Driveshaft of a Turbofan Engine". Advanced Materials Research 44-46 (czerwiec 2008): 127–34. http://dx.doi.org/10.4028/www.scientific.net/amr.44-46.127.
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In a turbofan engine, the high pressure rotor and the radial driveshaft, which transmit the power from the internal gear-box to the external gear-box, are geared by a spiral bevel gear pair. In this paper, a reasonably simplified dynamic model of the coupled rotors system is established, and then, the coupled stiffness matrix and coupled damping matrix of the spiral bevel gear pair are deduced. A shaft element method is proposed to investigate the lateral-torsional coupled vibration equations of the gear-rotor system. Furthermore, the mode shapes and unbalance responses of this two rotors coupled system are simulated. The results indicate that the system derives many new modes and the exciting forces on a rotor of the system would be passed to the other rotor for the gears meshing. When the rotor dynamics of a turbofan engine is being analyzed, the high pressure rotor and the radial drive shaft must be viewed as a whole. The dynamic balance precision of the rotors should be qualified properly, in order to improve the dynamic quality of the turbofan engine.
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Wang, Nanfei, Dongxiang Jiang i Hongzhi Xu. "Dynamic characteristics analysis of a dual-rotor system with inter-shaft bearing". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, nr 3 (25.12.2017): 1147–58. http://dx.doi.org/10.1177/0954410017748969.
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The dual-rotor structure is susceptible to vibration, causing the malfunction of the entire operating system. In order to avoid the resonance during operation, it is significant and necessary to conduct modal analysis of such rotors. The dynamic analysis of the full dual-rotor system under operating conditions is also necessary to study dynamic characteristics of the rotating system. In this paper, one-dimension Timoshenko beam-type model, including the effects of gyroscopic moments, rotary inertias, bending and shear deformations, and three-dimension model for dual-rotor system with inter-shaft bearing are developed. Critical speed tests of dual-rotor are carried out to verify the analytical results. Based on the finite element models, the first critical speed excited by inner rotor and the first two critical speeds excited by outer rotor are calculated. The comparisons between both finite element models indicate that 1D model costs less time, which can be used to predict the critical speeds. Good agreement between the theoretical and experimental results shows the accuracy of the FE models. The Campbell diagram, critical speeds, operational deflection shapes and unbalance response of the dual-rotor are obtained to fully study the dynamic characteristics of the dual-rotor system.
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Zhang, Nan, Ying Liu i Fulei Chu. "Dynamic Characteristics of Flow Induced Vibration in a Rotor-Seal System". Shock and Vibration 18, nr 1-2 (2011): 139–46. http://dx.doi.org/10.1155/2011/364805.
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Flow induced vibration is an important factor affecting the performance of the rotor-seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the fluid force, which is induced by the interaction between the unstable fluid flow in the seal and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear models. Various nonlinear phenomena of flow induced vibration in the rotor-seal system, such as synchronization phenomenon and amplitude mutation, are reproduced.
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Han, Q., Z. Zhang i B. Wen. "Periodic motions of a dual-disc rotor system with rub-impact at fixed limiter". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, nr 10 (1.10.2008): 1935–46. http://dx.doi.org/10.1243/09544062jmes947.
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Periodic motions of a rotor system with two discs are investigated where rub-impacts occur at fixed limiter for a test rig with dual discs. First, a finite element (FE) model of the rotor system is developed. Then numerical simulations based on the FE model are conducted to study the rotor transverse vibrations of the rotor system under three typical cases with different rotating speeds, rub-impact clearances, rub-impact rod stiffness, and rub frictions. The results are further compared with typical multiperiodic characteristics by experimentally measured vibrations. The simulations demonstrate different rotor motions, including periodic, quasi-periodic or complex characteristics, which coincide with experimental measurements. Finally, the non-stationary time-frequency domain characteristics of rub-impact motions are investigated via the Hilbert—Huang transform, and intrinsic mode functions (IMFs) and instantaneous frequencies of the three typical cases are obtained. The research has revealed some of the inherent vibration features of the dual-disc rotor system with rub-impact only occurring at fixed limiters.
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Wang, Jinhong, Zhenping Li, Hongguang Li, Wendi Zhang i Ke Bao. "Dynamics analysis of the nonlinear rotor system with Geislinger coupling". Vibroengineering PROCEDIA 49 (18.05.2023): 73–79. http://dx.doi.org/10.21595/vp.2023.23334.
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Rotor systems with coupling consist of two rotors, rolling bearings, sealing components, and nonlinear coupling. Currently, rotor systems with coupling are widely used in marine engines, aerospace engines, and various vehicle engines. In studies of rotor systems with coupling, the coupling connecting both sides of the rotor are often regarded as a linear stiffness unit. But in actual engineering, the torsional stiffness of the coupling varies with the speed of the system, and the variation of the coupling stiffness will affect the dynamic characteristics of the rotor. Based on the above phenomena, this study establishes the rotor model of driveshaft-Geislinger coupling-driveshaft in diesel engines and obtains the modal, frequency, and transient response analysis results of the rotor system with nonlinear Geislinger coupling. The modal, frequency, and transient response analysis results of the nonlinear model are compared with those of the linear model. This study can provide theoretical support for the vibration analysis of nonlinear rotor systems with connected Geislinger coupling.
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Zhu, Rui, Guang-chao Wang, Qing-peng Han, An-lei Zhao, Jian-xing Ren i Xin Xia. "Dynamic Characteristics and Experimental Research of a Two-Span Rotor-Bearing System with Rub-Impact Fault". Shock and Vibration 2019 (15.09.2019): 1–15. http://dx.doi.org/10.1155/2019/6309809.
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Rotor rub-impact has a great influence on the stability and safety of a rotating machine. This study develops a dynamic model of a two-span rotor-bearing system with rubbing faults, and numerical simulation is carried out. Moreover, frictional screws are used to simulate a rubbing state by establishing a set of experimental devices that can simulate rotor-stator friction in the rotor system. Through the experimental platform and its analysis system, the rubbing experiment was conducted, and the vibration of the rotor-bearing system before and after the critical speed is observed. Rotors running under normal condition, local slight rubbing, and severe rubbing throughout the entire cycle are simulated. Dynamic trajectories, frequency spectrum diagrams, chart of axis track, and Poincare maps are used to analyze the features of the rotor-bearing system with rub-impact faults under various parameters. The vibration characteristics of rub impact are obtained. Results show that the dynamic characteristics of the rotor-bearing system are affected by the change in velocity and degree of impact friction. The findings are helpful in further understanding the dynamic characteristics of the rub-impact fault of the two-span rotor-bearing system and provide reference for fault diagnosis.
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Zheng, Nan, Moli Chen, Guihuo Luo i Zhifeng Ye. "Coupled Lateral and Torsional Vibration of Rub-Impact Rotor during Hovering Flight". Shock and Vibration 2021 (13.10.2021): 1–25. http://dx.doi.org/10.1155/2021/4077556.
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When aircraft make a maneuvering during flight, additional loads acting on the engine rotor system are generated, which may induce rub-impact faults between the rotor and stator. To study the rub-impact response characteristics of the rotor system during hovering flight, the dynamic model of a rub-impact rotor system is established with lateral-torsional vibration coupling effect under arbitrary maneuvering flight conditions using the finite element method and Lagrange equation. An implicit numerical integral method combining the Newmark-β and Newton–Raphson methods is used to solve the vibration response. The results indicate that the dynamic characteristics of the rotor system will change during maneuvering flight, and the subharmonic vibrations are amplified in both lateral and torsional vibrations due to maneuvering overload. The form of the rub-impact is different during level and hovering flight conditions: the rub-impact may occur at an arbitrary phase of the whole cycle under the condition of level flight, while only local rub-impact occurs during hovering flight. Under the both flight conditions, the rub-impact has a large effect on the spectral characteristics, periodicity, and stability of the rotor system.
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Shevchenko, Serhii S. "General Approach to Modeling of Non-Contact Seals and Their Effect on the Dynamics of a Centrifugal Machine Rotor". Journal of Mechanical Engineering 25, nr 1 (30.03.2022): 32–39. http://dx.doi.org/10.15407/pmach2022.01.032.
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There is a constant demand for higher equipment parameters, such as pressure of a sealing medium and shaft rotation speed. However, as the parameters rise it becomes more difficult to ensure hermetization efficiency. Moreover, sealing systems affect the overall operational safety of the equipment, especially vibratory. Non-contact seals are considered as hydrostatodynamic supports that can effectively damp rotor oscillations. Models of an impulse and a groove seals, models of rotor-seals system and rotor-auto-unloading system, model of a shaftless pump are studied to evaluate an effect of these sealing systems on oscillatory characteristics of rotor. Analytical dependencies for computation the dynamic characteristics of impulse seals, hydromechanical systems rotor-seals and rotor-auto-unloading, as well as shaftless pumps are obtained. These dependencies describe the radial-angular vibrations of a centrifugal machine rotor in seals-supports. Equations for computation the amplitude-frequency characteristics are given. The directions of improving the оperational safety of critical pumping equipment by purposefully increasing the rigidity of non-contact seals that leads to higher rotor vibration stability have been determined.
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Chu, Xin Xing, i Feng Lan Wang. "Analysis of Vibration Characteristics of a Cracked Rotor". Applied Mechanics and Materials 620 (sierpień 2014): 296–99. http://dx.doi.org/10.4028/www.scientific.net/amm.620.296.
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This paper studies the Jeffcott cracked rotor based on level set, considering the oil film oscillation effects on crack rotor, building the stiffness matrix of the cracked rotor in the fixed coordinate system and the moving coordinate, deriving the nonlinear differential equations of coupled vibration of a cracked rotor, and analysis of its dynamic characteristic combined with case. Analysis shows that: crack rotor can produce nonlinear vibration in the crack and Oil film oscillation can be coupled bending and torsional vibration of cracked rotor. The analysis results provides practical basis for diagnosing Resonance of the rotor system fault and the safe operation of rotor.
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Aimeur, Noureddine, i Noureddine Menasri. "Computational Investigation of Vibration Characteristics Analysis for Industrial Rotor". Acta Mechanica et Automatica 16, nr 4 (8.11.2022): 373–81. http://dx.doi.org/10.2478/ama-2022-0044.
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Abstract During the operation of a rotor, various types of vibrations appear in this mechanical system and often limit the performance and endanger the safety of the operation. Therefore, dynamic analysis is essential because precise knowledge of the vibration behaviour is essential to ensure proper operation. This article presents a set of scientific techniques for the modelling and simulation of rotor vibrations. To work out the equations of the vibratory movement of the rotor, we used the energy approach of Lagrange. To achieve this, a model with one blading wheel carried by a shaft supported by two hydrodynamic bearings is chosen basedon the characteristics of the rotor studied (Fan 280 cement draft fan). It is an arduous task to manually ascertain the analytical resolution of the differential equations that characterise the vibratory behaviour of the rotor. The numerical approach employing the finite element method, programmed on the ANSYS software, made it possible to perform the vibration analysis of the rotor. First, the FAN 280 cement draft fan rotor is modelled using SolidWorks 3D software and reverse design using the coordinate measuring machine (CMM) for the design of the fins. Then, the modal characteristics of the fan rotor model were analysed using the finite element analysis (FEA) software ANSYS Workbench. Also, to study the effect of blade wear on critical speeds, the Campbell diagram was obtained. Finally, harmonic analysis was performed to determine the amplitude of the rotor vortex at critical speeds obtained with and without blade wear.
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Xu, Yeyin, Runchao Zhao, Yinghou Jiao i Zhaobo Chen. "Stability and bifurcations of complex vibrations in a nonlinear brush-seal rotor system". Chaos: An Interdisciplinary Journal of Nonlinear Science 33, nr 3 (marzec 2023): 033113. http://dx.doi.org/10.1063/5.0134907.
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A brush seal has the advantages of adapting to different vibration conditions and increasing the stability of the nonlinear rotor system. In this research, the stability and bifurcations of complex vibrations in a brush-seal rotor system are studied. An analytical seal force model is obtained through the beam theory and mutual coupling dynamics of the bristles and the rotor. The interaction between the bristles and the rotor is clearly depicted by a geometric map. Periodic and chaotic vibrations as well as the corresponding amplitude–frequency characteristics are first predicted by a numerical bifurcation diagram and 3D waterfalls. Discrete dynamic eigenvalue analysis is adopted for a detailed investigation of the stability and bifurcations of nonlinear vibrations. Jumping, quasi-periodic, and half-frequency vibrations are warned during the speeding up and down process. Four separate nonlinear vibration evolving routes are discovered. Two period-doubling bifurcation trees evolving to chaos are illustrated for the observation of global and independent periodic vibrations. Nonlinear vibration illustrations are presented through displacement orbits as well as harmonic amplitudes and phases. Chaotic vibration and unstable semi-analytical vibration solutions are compared. The obtained results and analysis methods provide new perspectives on nonlinear vibrations in the brush-seal rotor system.
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Wang, Zhipeng, Yunbo Yuan, Zhiyong Wang, Wei Liu, Yibin Guo i Donghua Wang. "Lateral-Torsional Coupling Characteristics of a Two-Stage Planetary Gear Rotor System". Shock and Vibration 2018 (31.05.2018): 1–15. http://dx.doi.org/10.1155/2018/4293475.
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Planetary gears are one part of the whole transmission chain, and the dynamics and vibration characteristics of them are strongly coupled with external rotors. In this paper, to demonstrate the interaction between multistage planetary gears and external rotors as well as investigate the lateral-torsional coupling characteristics of them, a coupling model of a two-stage planetary gear rotor system is proposed. In such a model, the two-stage planetary gear subsystem is established as a lumped-parameter model and the external rotor subsystem is established as a finite element model. The vibration mode distribution properties and lateral-torsional coupling characteristics are both analyzed by modal strain energy. Three different conditions are considered: uncoupled, partially coupled, and fully coupled. The results indicate that the coupling among multiple subsystems and the lateral-torsional coupling mainly exist in the low-mode region. Natural frequencies dominated by the two-stage planetary gear subsystem are sensitive to coupled conditions, whereas natural frequencies dominated by the input rotor subsystem are remarkably insensitive to coupled conditions. Furthermore, the natural frequency of the first torsional mode can be obtained only in the fully coupled condition. Experiments are implemented to obtain natural frequencies, and the experiment results validate the numerical results.
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Jin, Yingze, Qiuli Niu, Yuanpeng Qu i Xiaoyang Yuan. "Pivot Stiffness Effect on Transient Dynamic Characteristic of Tilting Pad Journal Bearing-Rotor System Passing through Critical Speed". Lubricants 11, nr 3 (10.03.2023): 125. http://dx.doi.org/10.3390/lubricants11030125.
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Tilting pad journal bearings (TPJBs) are widely applied in the high-speed rotor system whose working speed is higher than its critical speed due to excellent hydrodynamic lubrication and stability. Pivot stiffness is one of the key design parameters of TPJBs compared to other journal bearings and has become particularly important for optimizing the performance of TPJB-rotor systems. In order to improve the vibration and critical characteristics of rotor systems, the transient dynamic characteristic of a TPJB-rotor system passing through the critical speed is investigated considering different pivot stiffness ratios. A time-varying dynamics model of a symmetrical single-disc rotor supported by four-pad TPJBs is established considering constant acceleration conditions and nonlinear hydrodynamic bearing force. The disc vibration characteristic, journal vibration characteristic, pad vibration characteristic, and hydrodynamic bearing force are analyzed by using Bode plot, shaft center orbit, pad phase orbit, waterfall plot, and time history. The results show that the pivot stiffness plays a major role in the suppression of resonance amplitude and working amplitude of a TPJB-rotor system, without changing the frequency characteristic of the system. This study provides a theoretical basis for the pivot stiffness design of TPJBs and the vibration suppression of rotor systems.
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Wang, Jiahao, Huabing Wen, Haiyu Qian, Junhua Guo, Junchao Zhu, Jiwei Dong i Hua Shen. "Typical Fault Modeling and Vibration Characteristics of the Turbocharger Rotor System". Machines 11, nr 2 (20.02.2023): 311. http://dx.doi.org/10.3390/machines11020311.
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To study the typical failure mechanism (rotor unbalance, rotor friction, and rotor crack) and vibration characteristics of the turbocharger rotor system, a rotor system dynamics simulation model was established by an improved four-node aggregate parameter method. The geometric and physical characteristics of the rotor system under three failure states and its dynamics under operation were analyzed. Thus, a typical failure dynamics simulation model of the rotor system was established. On this basis, the output failure simulation signal was extracted using the Hu invariant moment feature extraction method to analyze the system vibration characteristics under each typical failure state of the rotor system. The results show that the model in this paper can effectively reduce the computational volume and computational time, and the errors of numerical simulation were less than 3%. When an unbalance fault occurred in the rotor system, the shaft trajectory was “0” shaped and the response spectrum was dominated by 1X. When the rotor system was frictional, the shaft trajectory was a slightly concave “8” shape, and the response spectrum was dominated by 0.5X. When the rotor system was cracked, the axial trajectory was a “vortex”, and the response spectrum was dominated by 0.5X. Thus, the study of typical failure mechanism and vibration characteristics of a turbocharger rotor system by simulation calculation is effective and has good research prospects, providing an important technical reference for dynamic analysis and fault diagnosis of the rotor system.
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Shevchenko, S. S. "Mathematical Modelling of Dynamic System Rotor – Groove Seals". Èlektronnoe modelirovanie 43, nr 3 (4.06.2021): 17–35. http://dx.doi.org/10.15407/emodel.43.03.017.
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Groove seals are considered as hydrostatic bearings that capable of effectively damping rotor vibrations. In order to determine the dynamic characteristics, a model of the rotor–groove seals system is considered. The radial forces and moments in groove seals had been estimated. Expressions of joint radial-angular rotor vibrations in groove seals had been obtained. Formulas had been proposed for constructing amplitude and phase frequency characteristics. An example of calculating the dynamic characteristics of a centrifugal machine rotor model is given.
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Ma, Pingping, Mingxin Shan, Jingyu Zhai, Hao Zhang i Qingkai Han. "Vibration Characteristics and Simulation Verification of the Dual-Rotor System for Aeroengines with Rub-Impact Coupling Faults". Shock and Vibration 2021 (26.04.2021): 1–24. http://dx.doi.org/10.1155/2021/6622065.
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To study the rub-impact fault between the dynamic and static parts of the rotor system of aeroengines, the dual-rotor system of a typical aeroengine is introduced and taken as the research object. The analytical kinetic model is established based on the Lagrange equation considering the structural characteristics of the dual-rotor system, the coupling effect of the intermediate bearing, and the rub-impact fault between the high-pressure turbine disc and the casing. The dynamic characteristics of the dual-rotor system under the rub-impact fault are analyzed, and the change rule of the rub-impact shape is obtained. The vibration coupling and transfer among the high-pressure rotor and the low-pressure rotor are revealed. The influence of the unbalanced position and the speed of high and low rotors on the vibration response of the dual rotor is obtained. The sensitivity of the vibration response of the dual rotor at different test points to rub-impact stiffness, clearance, and friction coefficient is compared. The simulation model is established based on the rigid-flexible coupling multibody dynamic simulation platform. The analytical results and simulation results are compared, which have a good consistency. The theoretical research can deepen the understanding of the nature and law of aeroengine rotor operation, expose the possible faults and design defects, greatly improve the development efficiency and quality, reduce repeated physical tests, reduce the development risk and cost, and accelerate the development process. This study can provide a theoretical basis for the monitoring and diagnosis of engine rub-impact faults and provide theoretical and practical reference for the establishment of the vibration fault test and analysis method system.
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Choy, F. K., Y. F. Ruan, R. K. Tu, J. J. Zakrajsek i D. P. Townsend. "Modal Analysis of Multistage Gear Systems Coupled With Gearbox Vibrations". Journal of Mechanical Design 114, nr 3 (1.09.1992): 486–97. http://dx.doi.org/10.1115/1.2926577.
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This paper presents an analytical procedure to simulate vibrations in gear transmission systems. This procedure couples the dynamics of the rotor-bearing gear system with the vibration in the gearbox structure. The modal synthesis method is used in solving the overall dynamics of the system, and a variable time-stepping integration scheme is used in evaluating the global transient vibration of the system. Locally each gear stage is modelled as a multimass rotor-bearing system using a discrete model. The modal characteristics are calculated using the matrix-transfer technique. The gearbox structure is represented by a finite element model, and modal parameters are solved by using NASTRAN. The rotor-gear stages are coupled through nonlinear compliance in the gear mesh while the gearbox structure is coupled through the bearing supports of the rotor system. Transient and steady state vibrations of the coupled system are examined in both time and frequency domains. A typical three-geared system is used as an example for demonstration of the developed procedure.
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Jia, Xingyun, Hai Zhang, Qun Zheng, Shuangming Fan i Zhitao Tian. "Investigation on Rotor-Labyrinth Seal System with Variable Rotating speed". International Journal of Turbo & Jet-Engines 36, nr 1 (26.03.2019): 19–29. http://dx.doi.org/10.1515/tjj-2016-0066.
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AbstractThe following paper presents dynamic leakage rate and coupled interaction for variable speed rotor-labyrinth (LABY) seal, with rotating speed from 18 to 30 krpm. Variable speed rotor vibration characteristics are incorporated into transient computational fluid dynamic (CFD) calculations as boundary conditions of seal flow field to show the real-time effect of rotordynamic in seal flow field. Leakage rate across a variable speed rotor-seal increases with rotor vibration, but this effect is prominent at lower speed than at higher speed. Leakage characteristic is determined by differences in rotor vibration amplitude rather than rotating speed. The results also reveal that aerodynamic forces of labyrinth seal flow field can improve rotor stability, and this interaction between rotor and seal decreases with the increase of rotating speed.
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Yadao, Adik Ramdayal, Ravi P. Singh i D. R. Parhi. "Influence of Parameters of Cracked Rotor System on its Vibration Characteristics in Viscous Medium at Finite Region". Applied Mechanics and Materials 592-594 (lipiec 2014): 2061–65. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.2061.
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The paper summarizes a complete analysis about vibrational characteristics of a spinning simply supported cracked shaft with fluid medium at finite region. The damping effect occurs due to external fluid is integrated in the existing analysis, with the help of navier - stokes equation. The simply supported cracked shaft is analyzed by the influence coefficient strain energy method. Here we have changing the parameter of shaft i.e. damping viscosity of fluid and the length of the shaft which accountable for the alteration of the amplitude of vibration.
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Yabui, Shota, i Tsuyoshi Inoue. "Development of optimal controller design method to compensate for vibrations caused by unbalanced force in rotor system based on Nyquist diagram". Journal of Vibration and Control 25, nr 4 (4.09.2018): 793–805. http://dx.doi.org/10.1177/1077546318797173.
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In this paper, an optimal controller design method is proposed to compensate for vibrations caused by unbalanced force in the rotor system. The vibrations caused by unbalanced force are the major root cause of excessive whirling vibration in the rotor system, and it is important to compensate for the vibration to maintain its stable operation. The proposed design method can optimize a performance of the controller based on the vector locus of open loop characteristics on the Nyquist diagram. To verifiy the effectiveness, the proposed design method was employed for three typical active vibration control methods. The experimental results show that the proposed method can design the optimal parameters to compensate for the whirling vibrations of the rotor system.
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Li, Chaofeng, Shihua Zhou, Shuhua Yang, Xiang Ren i Bangchun Wen. "Dynamic Characteristics of Blade-Disk-Rotor System with Structural Mistuned Features". Open Mechanical Engineering Journal 8, nr 1 (18.04.2014): 138–43. http://dx.doi.org/10.2174/1874155x20140501008.
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The finite element method is adopted to establish the dynamical models of blade, bladed disk and blades-diskshaft assemblies. Based on the analysis of mistuned structure and the dynamic characteristics of model in different levels, it gives the vibration mode distribution of different models. The research shows that the characteristics of the bladed disk and shaft have a huge difference, where some modes are caused by the strongly split and coupled vibration. The mistuned effects are likely to cause different coupled vibrations of blades between the blades-disk model and the blades-disk-shaft model. Meanwhile, it shows the frequency separation and concentration, and misses the system mode and the local vibration, which bring some difficulties for designing the blade-rotor system. In this paper, the results may provide a certain reference for blade-rotor system design and diagnosis.
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Xu, Hongzhi, Nanfei Wang, Dongxiang Jiang, Te Han i Dewang Li. "Dynamic Characteristics and Experimental Research of Dual-Rotor System with Rub-Impact Fault". Shock and Vibration 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/6239281.
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Rub-impact fault model for dual-rotor system was further developed, in which rubbing board is regarded as elastic sheet. Sheet elastic deformation, contact penetration, and elastic damping support during rubbing of sheet and wheel disk were considered. Collision force and friction were calculated by utilizing Hertz contact theory and Coulomb model and introducing nonlinear spring damping model and friction coefficient. Then kinetic differential equations of rub-impact under dry rubbing condition were established. Based on one-dimensional finite element model of dual-rotor system, dynamic transient response of overall structure under rub-impact existing between rotor wheel and sheet was obtained. Meanwhile, fault dynamic characteristics and impact of rubbing clearance on rotor vibration were analyzed. The results show that, during the process of rub-impact, the spectrums of rotor vibration are complicated and multiple combined frequency components of inner and outer rotor fundamental frequencies are typical characteristic of rub-impact fault for dual-rotor system. It also can be seen from rotor vibration response that the rubbing rotor’s fundamental frequency is modulated by normal rotor double frequency.
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Wang, Meiling, Baogang Wen, Qingkai Han, Yibo Sun i Changxin Yu. "Dynamic Characteristics of a Misaligned Rigid Rotor System with Flexible Supports". Shock and Vibration 2021 (15.04.2021): 1–16. http://dx.doi.org/10.1155/2021/8876190.
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A misaligned rigid rotor system with flexible supports differing from the traditional flexible rotor system, which refers to its practical rotating center line determined by supports offset from the theoretical one, often suffers support structure damage risk. In the present work, the dynamic characteristics of a misaligned rigid rotor system with flexible squirrel cage supports are focused, and the vibrations and the stress of its support structures under different misaligned offsets are investigated with experimental and simulated analysis. The finite element model for a rigid rotor system with flexible supports in a scaled test rig is established, and its strain energy distribution is analyzed to find that the first two modes of the system are referred to rigid-body modes and the strain energy is mainly distributed on the squirrel cage supports. Based on the analysis results, a rigid-flexible coupling dynamic model is proposed through a data exchange between ADAMS and ANSYS and validated by measurements. The misaligned conditions are focused on, and the influences of misalignment on the vibrations of the rigid rotor system and the reaction force and stress of its support structures are investigated analytically and experimentally. The results from simulation agree very well with the measurements and reveal that the static stress of squirrel cage increases just about proportionally with misalignment levels, but the vibration displacement amplitudes and stress amplitudes show very little change. The more serious the misaligned condition, the higher the static stress of the squirrel cage. Because misalignment will bring out the additional reaction forces in the misaligned direction, it will further result in higher stress and even more serious damage risk for the flexible supports than other parts in the rigid rotor system.
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Sawicki, Jerzy T., Joe Padovan i Rabih Al-Khatib. "The Dynamics of Rotor with Rubbing". International Journal of Rotating Machinery 5, nr 4 (1999): 295–304. http://dx.doi.org/10.1155/s1023621x99000263.
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This paper presents the description of some phenomena associated with dynamic behavior of rotors interacting with stationary components. Numerical simulations show rotor vibration spectrum rich in subharmonic, quasi-periodic, and chaotic vibrations. The nonlinear calculation techniques are applied to demonstrate the changes of the vibration patterns for different operating conditions. Some conclusions are discussed with regard to unique characteristics of rub-induced rotor response, initial conditions, as well as appropriate ranges of system parameters. Of special interest are the changes in the apparent nonlinearity of the system dynamics as rubs are induced at different rotor speeds. In particular, starting with 2nd order sub/superharmonics, which are symptomatic of quadratic nonlinearity, progressively higher order polynomial behavior is excited, i.e., cubic, giving rise to 3rd order sub/superharmonics. As the speed is transitioned between such apparent nonlinearities, chaotic like behavior is induced because of the lack of whole or rational tone tuning between the apparent system frequency and the external source noise. The cause of such behavior will be discussed in detail along with the results of several parametric studies.
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An, Xueli, i Fei Zhang. "Pedestal looseness fault diagnosis in a rotating machine based on variational mode decomposition". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, nr 13 (9.03.2016): 2493–502. http://dx.doi.org/10.1177/0954406216637378.
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According to the non-stationary characteristic of rotating machinery vibration signals of a rotor system with a loose pedestal fault, variational mode decomposition was applied in the pedestal looseness fault diagnosis for such a rotor system. Variational mode decomposition is used to decompose the rotor vibration signal into several stable components. This can achieve the separation of the pedestal looseness fault signal from the background signals, and extract the fault characteristic of a vibration signal from a rotor system with pedestal looseness. Experimental data from a rotor system with pedestal looseness were used to verify the proposed method. The results showed that the stable components of the rotor vibration signal obtained by variational mode decomposition have obvious amplitude modulation characteristics. The components which contain fault information were analyzed by envelope demodulation, which can extract the pedestal looseness fault features of a rotor vibration signal. Therefore, the variational mode decomposition method can be effectively applied to the pedestal looseness fault diagnosis of such a rotor system.
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Wang, Nanfei, Hongzhi Xu i Dongxiang Jiang. "Dynamic Model and Fault Feature Research of Dual-Rotor System with Bearing Pedestal Looseness". Mathematical Problems in Engineering 2016 (2016): 1–18. http://dx.doi.org/10.1155/2016/3817405.
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The paper presents a finite element model of dual-rotor system with pedestal looseness stemming from loosened bolts. Dynamic model including bearing pedestal looseness is established based on the dual-rotor test rig. Three-degree-of-freedom (DOF) planar rigid motion of loose bearing pedestal is fully considered and collision recovery coefficient is also introduced in the model. Based on the Timoshenko beam elements, using the finite element method, rigid body kinematics, and the Newmark-βalgorithm for numerical simulation, dynamic characteristics of the inner and outer rotors and the bearing pedestal plane rigid body motion under bearing pedestal looseness condition are studied. Meanwhile, the looseness experiments under two different speed combinations are carried out, and the experimental results are basically the same. The simulation results are compared with the experimental results, indicating that vibration displacement waveforms of loosened rotor have “clipping” phenomenon. When the bearing pedestal looseness fault occurs, the inner and outer rotors vibration spectrum not only contains the difference and sum frequency of the two rotors’ fundamental frequency but also contains2Xand3Xcomponent of rotor with loosened support, and so forth; low frequency spectrum is more, containing dividing component, and so forth; the rotor displacement spectrums also contain fewer combination frequency components, and so forth; when one side of the inner rotor bearing pedestal is loosened, the inner rotor axis trajectory is drawn into similar-ellipse shape.
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Zhang, Nan. "Flow Induced Vibration in the Seal System". Applied Mechanics and Materials 644-650 (wrzesień 2014): 390–93. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.390.
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The oscillating flow is an important factor affecting the performance of the rotor–seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the self-excited vibration, which is induced by interaction between the unstable seal fluid flow and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear model with the flow induced vibration.
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Liu, Jing, Yajun Xu i Yimin Shao. "Dynamic modelling of a rotor-bearing-housing system including a localized fault". Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 232, nr 3 (27.10.2017): 385–97. http://dx.doi.org/10.1177/1464419317738427.
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An in-depth understanding of the dynamic characteristics through rotor-bearing-housing systems is very valuable for fault detection and diagnosis applications of rotating machines such as high-speed spindle, roll mill, gearbox, engines, etc. A new vibration model of a rotor-bearing-housing system considering the rotor compliance, elastic interface between the housing and outer race, housing compliance, and time-dependent excitations introduced by a localized fault on the inner and outer races of an inherent ball bearing is proposed in this work. An analytical method for calculating the time-dependent excitations including the time-dependent displacement excitation and contact stiffness coefficient between the ball and fault edges is presented. Differences between vibration responses of a rotor-bearing-housing system from the proposed model and the previous model without the rotor compliance in the literature are discussed. The presented model is used to discuss the influences of all the rotor compliance, housing compliance, and fault sizes on the races of the inherent ball bearing on the vibration responses and vibration transmission characteristics through the rotor-bearing-housing system, which cannot be formulated by the current dynamic models in the listed references. An experimental study is introduced to validate the presented model. The results show that the rotor compliance and time-dependent contact stiffness coefficient caused by the fault have great influence on the dynamic characteristics through the rotor-bearing-housing system. It also seems that the developed method can provide a new vibration modelling method for the vibration analysis for a rotor-bearing-housing system with and without the faults.
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Sun, Huer, Zhao Jian Yang, Qun Long Liang i Xin Yu Pang. "Characteristics Identification of Overlapping Vibration Signals on Mallat". Advanced Materials Research 97-101 (marzec 2010): 4375–78. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.4375.
Pełny tekst źródłaStreszczenie:
In rotor-bearing system running, vibration signals measured were an kind of Multi-vibration source signals which is overlapping each other. These overlapping signals were difficult to be separated by the ordinary methods, which is adverse to precisely estimate faults of rotor-bearing system in running. In this paper, a test rig was set up to simulate mis-alignment faults; collected vibration signals of bearings were decomposed and reconstructed by algorithm of Mallat. Reconstructed signal can reflect detail character s of bearings vibration. And vibration signals characteristics of fault rotor were effectively identified.
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Asdaque, P. M. G. Bashir, i R. K. Behera. "Vibration Analysis of Hollow Tapered Shaft Rotor". Advances in Acoustics and Vibration 2014 (28.04.2014): 1–14. http://dx.doi.org/10.1155/2014/410851.
Pełny tekst źródłaStreszczenie:
Shafts or circular cross-section beams are important parts of rotating systems and their geometries play important role in rotor dynamics. Hollow tapered shaft rotors with uniform thickness and uniform bore are considered. Critical speeds or whirling frequency conditions are computed using transfer matrix method and then the results were compared using finite element method. For particular shaft lengths and rotating speeds, response of the hollow tapered shaft-rotor system is determined for the establishment of dynamic characteristics. Nonrotating conditions are also considered and results obtained are plotted.