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Journal articles on the topic 'Rotor ends'
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1
Daif, Omar S., M. Helmy Abd El-Raouf, Mohamed Adel Esmaeel, and Abd Elsamie B. Kotb. "Economic design of sleeve rotor induction motor using rotor ends." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 2 (2022): 1233. http://dx.doi.org/10.11591/ijece.v12i2.pp1233-1242.
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<span>In this paper, the field analysis of the sleeve rotor induction motor (IM) is carried out taking the rotor ends into consideration. Here, the field system equations are derived using the cylindrical model with applying Maxwell's field equations. It is expected that, both starting and maximum torques will increase with taking the rotor ends than that without rotor ends. A simple model is used to establish the geometry of the rotor ends current density and to investigate the air gap flux density. The magnetic flux is assumed to remain radially constant through the very small air gap length between the sleeve and stator surfaces. Variation of the field in the radial direction is ignored and the skin effect in the axial direction is considered. The axial distributions of the air gap flux density, the sleeve current density components and the force density have been determined. The motor performance is carried out taking into account the effects of the rotor ends on the starting and normal operations. The sleeve rotor resistance and leakage reactance have been obtained in terms of the cylindrical geometry of the machine. These equivalent circuit parameters have been calculated and plotted as functions of the motor speed with and without the rotor ends.</span>
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Omar, S. Daif, Helmy Abd Raouf M., Adel Esmaeel Mohamed, and Elsamie B. Kotb Abd. "Economic design of sleeve rotor induction motor using rotor ends." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 2 (2022): 1233–42. https://doi.org/10.11591/ijece.v12i2.pp1233-1242.
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In this paper, the field analysis of the sleeve rotor induction motor (IM) is carried out taking the rotor ends into consideration. Here, the field system equations are derived using the cylindrical model with applying Maxwell's field equations. It is expected that, both starting and maximum torques will increase with taking the rotor ends than that without rotor ends. A simple model is used to establish the geometry of the rotor ends current density and to investigate the air gap flux density. The magnetic flux is assumed to remain radially constant through the very small air gap length between the sleeve and stator surfaces. Variation of the field in the radial direction is ignored and the skin effect in the axial direction is considered. The axial distributions of the air gap flux density, the sleeve current density components and the force density have been determined. The motor performance is carried out taking into account the effects of the rotor ends on the starting and normal operations. The sleeve rotor resistance and leakage reactance have been obtained in terms of the cylindrical geometry of the machine. These equivalent circuit parameters have been calculated and plotted as functions of the motor speed with and without the rotor ends.
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Whalley, R., and M. Ebrahimi. "Torsional Vibrations in Rotor Shells." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 212, no. 4 (1998): 263–76. http://dx.doi.org/10.1177/095440629821200402.
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Rotors comprising a motor-driven thin cylindrical shell with rigidly attached ends and torsional dampers, all of which are supported on bearings, are investigated. Analysis procedures enabling the variations in the model singularities with parameter changes are outlined. General results are derived indicating that the system damping ratio is maximized under specific operating conditions. A typical high-speed rotor for a paper manufacturing process is considered and analytical and simulation results are presented, confirming the predicted optimum damper settings and thereby minimizing the transient oscillations.
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de Santiago, O., L. San Andre´s, and J. Oliveras. "Imbalance Response of a Rotor Supported on Open-Ends Integral Squeeze Film Dampers." Journal of Engineering for Gas Turbines and Power 121, no. 4 (1999): 718–24. http://dx.doi.org/10.1115/1.2818532.
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Rotor vibration attenuation and structural components isolation in jet engines are achieved with squeeze film dampers, many of them supported on long elastic squirrel cages. Integral squeeze film dampers (ISFDs) are comprised of arcuate pads and wire-EDM webs rendering a compact viscoelastic support. An experimental study is conducted to evaluate the effectiveness of ISFDs in attenuating the imbalance response of a massive test rotor. Measurements of the damper structural stiffness and rotor natural frequencies are detailed. Impact tests on the test rotor supported on its dampers reveal the supporting structure to be very flexible, thus requiring the experimental evaluation of an equivalent stiffness for the damper and supports system. System damping coefficients extracted from impact load excitations vary with the lubricant viscosity and include a significant structural damping from the bearing supports. Rotor coast-down tests demonstrate the ISFDs to damp well the rotor response with peak vibration amplitude proportional (linear) to the imbalance. Viscous damping coefficients estimated from the amplitude response at the critical speeds agree reasonably well with predictions from a full-film, finite element model.
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Zhao, Fang, Jun Ming Zhang, Wei Wang, and De Rong Duan. "Research on the Load Distribution of Throwing Ends in Vertical Shaft Impact Crusher." Advanced Materials Research 156-157 (October 2010): 1463–66. http://dx.doi.org/10.4028/www.scientific.net/amr.156-157.1463.
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With ADAMS dynamics software to simulate the stone movement in the vertical shaft impact crusher rotor, the law of an impact frequency and load on the throwing ends with the variation of feed size and rotor speed is studied, the reasons that the middle throwing end is most vulnerable to wear failure and the rotor speed is not as high as possible are explained.
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Recalde-Camacho, L., W. Leithead, L. Morgan, and A. Kazemi Amiri. "Controller design for the X-Rotor offshore wind turbine concept." Journal of Physics: Conference Series 2767, no. 3 (2024): 032050. http://dx.doi.org/10.1088/1742-6596/2767/3/032050.
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Abstract This paper explores the design of a full envelope speed controller to operate the X-Rotor Offshore Wind Turbine. The X-Rotor is a heavily modified V-rotor vertical axis wind turbine, in which the primary rotor has conventional blades angled both up and down from the ends of a relatively short and stiff cross-arm. The upper half employs full span blade pitching for speed regulation and the lower half is aimed at reducing overturning moments on the main bearing and provides power take-off through compact secondary horizontal axis turbines mounted at the tip of the lower blades. The operational strategy is somewhat similar to that of a variable speed pitch regulated horizontal axis wind turbine, however it differs in the following aspects: the way aerodynamic torque is balanced across the operating envelope, the adjustment of equilibrium operating points at below rated operation, the relationship of aerodynamic torque on the primary rotor to pitch angle, and the operation of the secondary rotors to increase energy capture. These aspects increase the complexity of the control strategy but also ease the controller requirements. The developed controller is tested on a turbine model with sufficient complexity to model the essential dynamic properties of the turbine concept.
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Roy, Haraprasad, Abhinav Khare, Saurabh Chandraker, and J. K. Dutt. "Fatigue based design and life estimation of viscoelastic rotors." Aircraft Engineering and Aerospace Technology 90, no. 1 (2018): 96–103. http://dx.doi.org/10.1108/aeat-01-2015-0015.
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Purpose High-speed rotor subjected to cyclic stress during operation may cause fatigue failure. Thus, the design of a rotor-shaft should involve the fatigue analysis for predicting safe life. Design/methodology/approach A damped rotor shaft with a centrally mounted disc, which is simulated as steam turbine rotor, is considered for fatigue analysis. The shaft is subjected to thermal load and axial torque. It is supported by two orthotropic flexible bearings at its two extreme ends. The bearings are modelled with two-element Voigt model along each orthogonal direction to consider the elastic damped behaviour. Finite element modelling is done through Rayleigh beam theory, where each element is also considered as a Voigt model. The mathematical model involves effect of external axial torque, softening and compressive action of the shaft due to thermal load by the high temperature steam. Findings This paper attempts to find dynamic stresses in a viscoelastic rotor-shaft subject to combined bending and torsional loading and is exposed to thermal environment during operation. The dynamic stress is then used to determine fatigue and also the life of rotors. Research limitations/implications Internal damping plays an important role in deciding dynamic behaviour of rotor shaft systems. Because of this, the rotor shaft becomes unstable after a certain spin speed. Thus, the design of the rotor based on fatigue analysis is limited to the stable zone. Practical implications For this purpose, equations of whirl motion of a viscoelastic rotor-shaft are first obtained after discretizing the continuum with finite beam elements and then the time domain solution of rotor displacement is used to find the bending stress and shear stress at various locations of the rotor. Location for the maximum stress decides the failure point. Safe rotor dimensions have been predicted by comparing dynamic stresses with the Soderberg diagram. Originality/value Design of rotor for safe life operation and prediction of stability could serve a good reference for designers.
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Glinka, Tadeusz, and Jakub Bernatt. "Asynchronous slip-ring motor synchronized with permanent magnets." Archives of Electrical Engineering 66, no. 1 (2017): 199–206. http://dx.doi.org/10.1515/aee-2017-0015.
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Abstract The electric LSPMSM motor presented in the paper differs from standard induction motor by rotor design. The insulated start-up winding is located in slots along the rotor circumference. The winding ends are connected to the slip-rings. The rotor core contains permanent magnets. The electromechanical characteristics for synchronous operation were calculated, as were the start-up characteristics for operation with a short-circuited rotor winding. Two model motors were used for the calculations, the V-shaped Permanent Magnet (VPM) – Fig. 3, and the Linear Permanent Magnet (IPM) – Fig. 4, both rated at 14.5 kW. The advantages of the investigated motor are demonstrated in the conclusions.
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Muszynska, Agnes. "Transition to Fluid-Induced Limit Cycle Self-Excited Vibrations of a Rotor and Instability Threshold “Hysteresis”." International Journal of Rotating Machinery 5, no. 2 (1999): 123–33. http://dx.doi.org/10.1155/s1023621x99000111.
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The transient process which starts at the instability threshold of a rotor rotating in a fluid environment, and ends up in the limit cycle of self-excited vibrations known as fluid whirl or fluid whip, is discussed in this paper. A one-lateral-mode, isotropic, nonlinear model of the rotor with fluid interaction allows for exact particular solutions and an estimation of the transient process. The fluid interacting with the rotor is contained in a small radial clearance area, such as in bearings, seals, or rotor-to-stator clearances, and its effects are represented by fluid film radial stiffness, damping, and fluid inertia rotating at a different angular velocities.The effects of fluid damping and fluid inertia circumferential velocity ratios on the rotor startup and shutdown instability threshold differences are also discussed.
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Kheder, Ahmed Samir, M. A. Elwany, and A. B. Kotb. "Analysis of Disc Motor with Asymmetrical Conducting Rotor." International Journal of Electrical and Electronics Research 12, no. 2 (2024): 487–92. http://dx.doi.org/10.37391/ijeer.120221.
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The homogenous disc rotor construction allows higher rotational speeds and relatively higher power densities. This paper deals with a two-phase induction motor with homogenous disc rotor construction. The field analysis of an axial flux disk motor with a conducting disc rotor is carried out, using a new application of the Maxwell's field equations. A Suggested model is introduced to establish the geometry of motor construction and to enable the derivation of the field system differential equations. A new strategy is applied for the boundary conditions to complete the field solution. This is carried out by determining the complex integration constants. The current density is completely derived with it is components (the radial, the tangential current density and the axial air gap flux density). The performance of the flux density, rotor current components and the torque-slip characteristics are determined with and without disk rotor ends. The effects of the disk rotor design data and the rotor asymmetry on the motor performance are investigated.
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Zhang, Qi, Zengliang Li, Ran Yu, Zhaocheng Sun, and Le Zhang. "Numerical Simulation of Internal Flow Field, Electromagnetic Field and Temperature Field in Deep-Water Motor." MATEC Web of Conferences 160 (2018): 02005. http://dx.doi.org/10.1051/matecconf/201816002005.
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In this paper, considering the heat exchange between the ends of stator&rotor and lubricating oil, the internal flow field model is established to analyse the flow state. The variation law of the pressure drops in the internal flow field and the friction loss of the rotor surface are specified. The operation characteristic of the motor and the variation law of the magnetic field loss are obtained through the analysis of motor magnetic field. Based on the results of internal flow field and magnetic field, the temperature distribution law of motor is obtained. Compared with the result of the temperature simulation in which only air gap path is considered, the stator temperature shows totally different distribution law, and the stator temperature increases from 32°C to 42°C. Compared with the result of the temperature simulation without considering heat source loss change, the maximum temperature of the motor decreases from 71°C to 49°C. The results show that the ends of stator&rotor and the variation of heat source loss can influence the temperature simulation results.
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San Andre´s, L., and D. Lubell. "Imbalance Response of a Test Rotor Supported on Squeeze Film Dampers." Journal of Engineering for Gas Turbines and Power 120, no. 2 (1998): 397–404. http://dx.doi.org/10.1115/1.2818136.
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Squeeze film dampers (SFDs) provide vibration attenuation and structural isolation to aircraft gas turbine engines which must be able to tolerate larger imbalances while operating above one or more critical speeds. Rotor-bearing-SFD systems are regarded in theory as highly nonlinear, showing jump phenomena and even chaotic behavior for sufficiently large levels of rotor imbalance. Yet, few experimental results of practical value have verified the analytical predictions. A test rig for measurement of the dynamic forced response of a three-disk rotor (45 kg) supported on two cylindrical SFDs is described. The major objective is to provide a reliable data base to validate and enhance SFD design practice and to allow a direct comparison with analytical models. The open-ends SFD are supported by four-bar centering structures, each with a stiffness of 3.5 MN/m. Measured synchronous responses to 9000 rpm due to various imbalances show the rotor-SFD system to be well damped with amplification factors between 1.6 and 2.1 while traversing cylindrical and conical modes critical speeds. The rotor amplitudes of motion are found to be proportional to the imbalances for the first mode of vibration, and the damping coefficients extracted compare reasonably well to predictions based on the full-film, open-ends SFD. Tight lip (elastomeric) seals contribute greatly to the overall damping of the test rig. Measured dynamic pressures at the squeeze film lands are well above ambient values with no indication of lubricant dynamic cavitation as simple theoretical models dictate. The measurements show absence of nonlinear behavior of the rotor-SFD apparatus for the range of imbalances tested.
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Guo, Yu Jie, and Wen Tao Zhang. "Research of Vibration Control Method on Turbine Bent Rotor." Applied Mechanics and Materials 275-277 (January 2013): 894–98. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.894.
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According to bent position and size on two HP-IP bent rotor,and combined with maintenance schedule,this paper puts forward two vibration control methods of low speed dynamic balance on site and high speed dynamic balance after turning.For the bent position in the turbine middle,on the basis of mode decomposition in bent rotor,the research show that balance weight according to a scale in the both ends and middle mainly of the turbine can achieve good results.
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Dutt, J. K., and B. C. Nakra. "Vibration Response Reduction of a Rotor Shaft System Using Viscoelastic Polymeric Supports." Journal of Vibration and Acoustics 115, no. 2 (1993): 221–23. http://dx.doi.org/10.1115/1.2930334.
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The main objective of the present work is to determine reduction in the unbalance response of a rotor shaft system by using a suitable polymeric or viscoelastic bearing support. For analysis, a simple rotor system has been taken with the rotor placed in the middle of a massless shaft with linear elastic bearings at the ends, having viscoelastic supports. A procedure is given for determining the frequency dependence of viscoelastic support characteristics so that the frequency of excitation never coincides with any of the undamped natural frequencies of the system, thus giving low unbalance response over a wide frequency range and the support material can be chosen accordingly.
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Das, Apurba, and Saiyed Muzaffar Ishtiaque. "END BREAKAGE IN ROTOR SPINNING: EFFECT OF DIFFERENT VARIABLES ON COTTON YARN END BREAKAGE." AUTEX Research Journal 4, no. 2 (2004): 52–59. http://dx.doi.org/10.1515/aut-2004-040201.
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Abstract The end breakage in rotor spinning not only reduces the running efficiency of the process, but also deteriorates the quality of the yarn in terms of presence of piecing slubs. A new system has been proposed to classify the end breaks in rotor spinning broadly into seven groups, depending on the configuration of broken ends. By examining the broken end, the probable causes of breakage can be predicted and necessary preventive action can be taken. The rate of end breakage and the proportion of different types of breakages vary with different process variables like yarn count, rotor speed, opening roller speed and residual trash content in draw frame sliver.
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Rabiela, Homero Jiménez, Benjamín Vázquez González, José Luis Ramírez Cruz, Adrian Gustavo Bravo Acosta, Pedro García Segura, and Miguel Ángel Hernández Vera. "Crack-Free Rotors for Responsible Consumption and Production." Journal of Lifestyle and SDGs Review 5, no. 1 (2024): e04073. https://doi.org/10.47172/2965-730x.sdgsreview.v5.n01.pe04073.
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Objective: The objective of this study is to investigate the effect of a crack on the elastic behavior of a rotor, for the early detection of the problem. Theoretical Framework: The theory of numerical methods and the theory of finite elements are applied to establish the range of revolutions per minute that will imply rotor resonance. Method: The methodology adopted for this investigation includes the virtual generation of the rotor, simply supported at its ends and with a concentrated load at the center, whose triangular diagonal chordal crack with variable inclination is caused by an isosceles triangle with constant height and width. Their deflections are calculated for different inclinations and orientations of the crack. Results and Discussion: The results obtained revealed variable shifts of the cross section with maximum deformation, with respect to the central cross section of the rotor, depending on the inclination and orientation of the crack. The results can be used to predict at an early stage the possibility of the birth and growth of a crack, as well as to prevent the subsequent fracture of the rotor. Research Implications: The results can be applied to the detection of cracks in a predictive or preventive stage, reducing or eliminating the corrective stage, avoiding thermal and noise pollution, increasing the safety of operators, avoiding damage to the infrastructure of companies and therefore to their economy. Originality/Value: This study contributes to literature by increasing the depth and extent of knowledge on cracked rotors and possible alternative solutions.
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Chen, Ya Zhe, Li Qun Liu, Yang Liu, and Bang Chun Wen. "Nonlinear Dynamics of Jeffcott Rotor System with Rub-Impact Fault." Advanced Engineering Forum 2-3 (December 2011): 722–27. http://dx.doi.org/10.4028/www.scientific.net/aef.2-3.722.
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The rub-impact fault of Jeffcott rotor system which is generally made of an elastic shaft with supported by two bearings at ends and a lumped mass at the mid-span of shaft is the main research subject of this paper. The mechanical model and finite element model of a lump mass at the mid-span of shaft is set up. The dynamics of it are studied by nonlinear finite element method under the rub-impact conditions, and by investigating the effects of stiffness of stator and the clearance between rotor-stator. From the study results, use finite element method to study the rotor system failure problem is intuitive and convenient, high accuracy, high reliability, can be widely applied.
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Günes, Doğan, Ergin Kükrer, and Tolga Aydoğdu. "Computational performance analysis of an airborne rotor-type electricity generator wind turbine." E3S Web of Conferences 128 (2019): 09007. http://dx.doi.org/10.1051/e3sconf/201912809007.
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This paper presents an analysis of the possible performance of a proposed airborne rotor type electricity generator wind turbine design. The innovative design proposal by inventor is based on the rotation of the airborne structure with blades attached to the airborne zeppelin and thus it is called an airborne rotor generator. In this paper computational fluid dynamics analysis of a model close to the proposed design is carried out and the results are presented. The proposed design examples are set to produce 10-100KW. The electrical energy generated through two symmetrically placed alternators at both ends of the zeppelin is transferred to the ground-based system through the tethered cords used to also stabilize the system. Thus, an airborne rotor generator is formed.
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Tang, Youfu, Feng Lin, and Qian Zou. "Dynamical Behavior Analysis of Rubbing Rotor System under Asymmetric Oil Film Force." Mathematical Problems in Engineering 2019 (July 14, 2019): 1–16. http://dx.doi.org/10.1155/2019/1253646.
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Rubbing is one of the most common and significant faults that exist in the rotor system. It exhibits extremely complicated dynamic behavior. Existing dynamic models are primarily based on the symmetrical rotor structure, in which the oil film forces at both ends of support are considered identical. However, in practice, the oil film force may be differently affected by multiple factors (e.g., viscosity of lubricants, the thickness of oil film, and clearance of journal bearing). In this study, a novel dynamic model of the rubbing rotor system under asymmetric oil film force was developed. Furthermore, based on the nonlinear rotor dynamic theory, its dynamic behavior with different parameters was analyzed, and the corresponding chaotic features were extracted. The results indicated that the evolution law of chaotic motion was more complicated, and the chaotic region of system response was obviously wider under the asymmetric oil film force than the symmetrical oil film force.
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Swaminathan, V. P., R. Viswanathan, and C. P. Clark. "Material Property Studies of Two High-Pressure Turbine Rotors for Remaining Life Assessment." Journal of Engineering Materials and Technology 116, no. 1 (1994): 19–26. http://dx.doi.org/10.1115/1.2904250.
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A remaining life assessment study was performed on two no-bore HP rotors after 169,000 hours of operation. These rotors were manufactured from 1CrMoV (ASTM A470, Class 8) steel. Southwest Research Institute conducted a materials evaluation program to generate pertinent material property data necessary to perform a SAFER analysis by Lehigh University. Two ring samples were removed from periphery locations of a rotor. One of the rings was from a packing location where the operating metal temperature was 860°F (460°C), and the other ring from the cold coupling end. Evaluation tests included chemical analysis, metallography, Auger analysis, tension and hardness, Charpy impact, fracture toughness, and stress rupture. A small sliver sample was available from the second rotor. Limited metallurgical analysis was conducted on this sample. Results indicated that the hot end embrittled in service with a shift in FATT of 240°F (116°C) when compared to the cold end. Fracture toughness versus temperature data were developed using various correlations available from the literature. Good correlation was found among the various procedures and lower bound curves were established for the hot and cold ends. Hot end toughness properties were significantly lower than those of the cold end. Auger results indicated segregation of phosphorus on the grain boundaries at the hot location. After service FATT can be predicted using the bulk phosphorus content and correlations available from the literature.
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Park, Cheol Hoon, Tae Gwang Yoon, Dongwoo Kang, and Hugo Rodrigue. "High-Precision Roller Supported by Active Magnetic Bearings." Applied Sciences 9, no. 20 (2019): 4389. http://dx.doi.org/10.3390/app9204389.
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Magnetic bearings support rotors in a non-contact way using magnetic force. Therefore, there is no friction and it is possible to measure and control the position of a rotor in the air gap. In this study, the rotational vibration of a roller was minimized using magnetic bearings, and a precision roller capable of automatic alignment using the position control function of magnetic bearings was proposed. A rotation accuracy of approximately 4.6 μm (peak-to-peak) was observed, even under a rotation of 30 rev/min and a radial force load of 300 N. The rotor position control experiment for magnetic bearings showed that 1-μm resolution position control is possible. To further improve the accuracy, the automatic alignment algorithm was proposed using magnetic bearings for the roller misalignment condition, and it was confirmed that alignment is possible at a level that the pressing force difference between both ends of the roller is within 0.3 N. Through this study, it was confirmed that rollers with magnetic bearings can be applied to precision equipment. It is expected that the implementation of the automatic alignment function will simplify the equipment configuration and maintenance compared to conventional rollers with ball bearings.
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Ding, Qian. "Backward Whirl and Its Suppression of a Squeeze Film Damper Mounted Rotor/Casing System in Passage through Critical Speed with Rubs." Journal of Vibration and Control 10, no. 4 (2004): 561–73. http://dx.doi.org/10.1177/1077546304036231.
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In this paper we consider a flexible Jeffcott rotor mounted at the ends by identical squeeze film dampers (SFDs). The rotative speed is supposed to increase at a constant angular acceleration. There can be one-peak and two-peak solutions for different values of SFD parameters during passage through the critical speed. Calculation shows that the rotor cannot pass through the critical speed due to the occurrence of diverging backward whirl in passage of the first or second peak, if the level of acceleration is lower than the critical ones. A flexible internal support, which can be activated or deactivated at a certain position along the rotor to change the stiffness of the system to suppress large vibration, is then applied to avoid the occurrence of backward whirl. The method is found to be effective if applied in a suitable way
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Alston, Peter V. "Effect of Yarn Spinning System on Pill Resistance of Polyester/Cotton Knit Fabrics." Textile Research Journal 62, no. 2 (1992): 105–8. http://dx.doi.org/10.1177/004051759206200208.
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We have determined the effect of ring, rotor, and air-jet spinning on the pill resistance of jersey and interlock fabrics. The jersey fabrics contained the same polyester type, while the interlock fabrics contained the preferred polyester for each spinning system. In each of the constructions, the air-jet spun fabrics were significantly more pill resistant than ring and rotor spun fabrics. Kinetic studies of the rates of pill formation and wear-off indicate that this difference is due to the much slower formation rate of the air-jet spun fabric. Analysis of pill character suggests that the tightly wrapped structure of the air-jet yarn inhibits the formation of free ends of polyester, which are the primary cause of the pills. Pill resistance for the ring spun fabric was only slightly better than for the rotor spun fabric when the same polyester type was used.
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Bhattacharyya, K., and J. K. Dutt. "Unbalance Response and Stability Analysis of Horizontal Rotor Systems Mounted on Nonlinear Rolling Element Bearings With Viscoelastic Supports." Journal of Vibration and Acoustics 119, no. 4 (1997): 539–44. http://dx.doi.org/10.1115/1.2889757.
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Unbalance response and stability analysis of a rotor shaft system, with the rotor mounted in the middle of a massless shaft, having linear elasticity and internal damping, with bearings having nonlinear restoring force characteristics at the ends mounted on viscoelastic support, has been carried out, taking the effect of gravity into account. The restoring force characteristics of the bearing has been linearized, by the method of effective linearization, thereby enabling an approximate stability analysis using simple techniques. It is found that, unlike the case with a bearing having linearly varying restoring force characteristics, gravity not only affects the unbalance response but also causes a decrease in the stability limits when the restoring force characteristics are nonlinear.
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Zeng, Qing Meng, Bao Tong Chai, and Hao Chen. "Research on Vibration Characteristics and Fault Diagnosis of 34CrMo1 Generator with Poor Heat Treatment." Applied Mechanics and Materials 893 (July 2019): 27–32. http://dx.doi.org/10.4028/www.scientific.net/amm.893.27.
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Poor heat treatment of the generator may cause cracks during operation. The presence ofcracks on the rotor causes the rotor to vibrate. The paper establishes a finite element modeling of aunit. The model is used to study the vibration response characteristics of the shafting system when thesupport characteristics of the generator are similar and the difference is significant. When thedifference in support characteristics between the two ends of the generator is large, the first-orderunbalance of the generator not only causes a large in-phase vibration at the first-order critical speed ofthe generator, but also causes a large reverse component. Finally, the reliability of the conclusion isfurther verified by combining the abnormal vibration diagnosis and processing cases of a generator.The innovation of the paper is to diagnose the possible cracks in the generator through the vibration ofthe generator, and then look at the original data in the generator manufacturing process to find that theheat treatment process of the generator rotor is poor.
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Ma, Jiaojiao, Chao Fu, Zhaoli Zheng, Kuan Lu, and Yongfeng Yang. "The Effects of Interval Uncertainties on Dynamic Characteristics of a Rotor System Supported by Oil-Film Bearings." Lubricants 10, no. 12 (2022): 354. http://dx.doi.org/10.3390/lubricants10120354.
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Rotating systems equipped with oil-film bearings are critical and common in many industrial machines. There are various non-random uncertainties in such fluid-lubricated dynamic systems. It is important to quantify the effects of uncertainties without adequate statistical information on the dynamics of rotor-bearing systems. In this paper, a rotor system with oil-film bearings at both ends is investigated considering many interval uncertainties. The rotating system is modeled in a deterministic sense. The Chebyshev interval method is used to track the propagation of different uncertainties. Deviations in the steady state responses, time history, and shaft orbits are calculated and comparatively discussed. Influence patterns of different interval parameters and dispersions in various dynamics are presented in detail. It is found that there can be global and local impacts as well as cumulative effects caused by multi-source uncertainties. The findings of the present study could be helpful for a more insightful dynamic analysis of rotor-bearing systems as well as their optimal design and maintenance.
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Yang, Zhenghao, and Guangyu He. "Effect of thermal barrier coating on thermal load of the rotor of the small aviation wankel engine." Journal of Physics: Conference Series 2125, no. 1 (2021): 012064. http://dx.doi.org/10.1088/1742-6596/2125/1/012064.
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Abstract Due to its high-altitude, low-temperature, high-load, and air-cooled working environment, small aviation rotary engines have problems such as large component load and low heat dissipation efficiency. As the main moving part of the engine, the rotor is continuously exposed to the complex temperature field of the engine. As an effective high-temperature protective coating, the thermal barrier coating can isolate the heat load generated by the work of the combustion chamber and effectively improve the complex work condition of the triangular rotor. This paper takes the triangular rotor of a small aviation Wankel engine as the research object, and establishes the finite element model of the rotor and the coating. The engine thermodynamic simulation model is established by Simulink, and the combustion chamber temperature and heat transfer coefficient are calculated. The heat transfer coefficients of the other surfaces of the rotor were calculated by series thermal resistance, which were used as boundary conditions for finite element analysis of the rotor and the coating. The temperature field, stress field and deformation of the rotor before and after processing the thermal barrier coating are compared. The results showed that after the thermal barrier coating, the temperature of the rotor will drop by about 50K on average. The temperature of the pit and cooling hole of the rotor will drop by 17K and 16K respectively, and the temperature of the inner edge and side end surface of the sealing groove will drop by about 10K. The stress values at the inner side of the rotor seal groove, the inner cavity cooling hole, and the inner hole of the rotor are reduced by about 35.4MPa, 29.4MPa, 33.4MPa, respectively, and the stress value at the bonding layer is 150MPa, which is significantly higher than the stress value at the corresponding position of the original rotor, indicating that there is stress Concentration phenomenon. At the same time, the deformation at both ends of the rotor seal groove is reduced from 61.92μm to 52.55μm, and the difference in the axial deformation of each position is less than 3mm. It can be obtained that the thermal barrier coating can effectively reduce the radial deformation of the rotor and has little effect on the axial deformation of the rotor.
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Shahzad, Muhammad, Tanveer Manzoor, Qanita Tayyaba, and Ammad Hussain Qureshi. "Twisting of the Tail Rotor Shaft - A Case Study." Key Engineering Materials 778 (September 2018): 28–32. http://dx.doi.org/10.4028/www.scientific.net/kem.778.28.
Full textAbstract:
Presented results report the findings of a case study carried out to determine the possible factors that lead to the twisting of tail rotor shaft. The structural materials of the shaft was evaluated in terms of microstructural analysis and mechanical properties to rule out any material fault. The SEM images showed that the localized fractures at twist ends occurred without any significant plastic deformation. Moreover, there was no evidence of fatigue. Such behavior suggests that twist occurred under impact / high strain rate loading. Such loading conditions are not possible during the event to ground hitting. The Ansys simulation confirmed that the observed twisting can increase the stress at localized point in excess of UTS and cause fracture.
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Globin, Andrey, Andrey Nesmiyan, Ivan Krasnov, Alexander Scherbakov, Vladimir Vanzha, and Leisan Akhtyamova. "Improving the operation process of a vane type vacuum pump for milking machines." E3S Web of Conferences 548 (2024): 01025. http://dx.doi.org/10.1051/e3sconf/202454801025.
Full textAbstract:
A description is given of the improved design of a pump with a rotating casing and flexible plates, used to create vacuum in milking machines. As a result of theoretical and experimental studies, the influence of its main parameters and operating modes on the volumetric flow was revealed. The most significant factors under consideration include: the rotation speed of the rotor and pump housing, the eccentricity of the rotor installation in the housing, the ratio of the width and diameter of the rotor, the size of the gaps at the ends. An analysis of the dynamics of air pressure in the working cell of the vane pump under consideration allowed us to conclude that the proposed modernization has a small impact directly on its distribution. It has been established that the most rational value for the end gaps is 70...90 microns. Within the given dimensions of the installation, the maximum of its specific productivity was achieved at a rotation speed of the working pair of about 1750 rpm, an eccentricity of about 23 mm and a ratio of width to rotor diameter of about 1.5.
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Sorge, Francesco. "Stability analysis of rotor whirl under nonlinear internal friction by a general averaging approach." Journal of Vibration and Control 23, no. 5 (2016): 808–26. http://dx.doi.org/10.1177/1077546315583752.
Full textAbstract:
The two main sources of internal friction in a rotor-shaft system are the shaft structural hysteresis and the possible shrink-fit release of the assembly. The internal friction tends to destabilize the over-critical rotor running, but a remedy against this effect may be provided by a proper combination of some external damping in the supports and an anisotropic arrangement of the support stiffness, or at most by the support damping alone, depending on the system geometry. The present analysis reported here considers a general asymmetric rotor-shaft system, where the rotor is perfectly rigid and is constrained by viscous–flexible supports having different stiffnesses on two orthogonal planes. The internal friction is modelled by nonlinear Coulombian forces, which counteract the translational motion of the rotor relative to a frame rotating with the shaft ends. The nonlinear equations of motion are dealt with using an averaging approach based on the Krylov-Bogoliubov method with some adaptation to address the multi-degree-of-freedom nature of the problem. Stable limit cycles may be attained by the overcritical whirling motions, whose amplitudes are inversely proportional to the external dissipation applied by the supports. A noteworthy result is that the stiffness anisotropy of the supports is recognized as beneficial in reducing the natural whirl amplitudes, albeit mainly in the symmetric configuration of the rotor at the mid span and, to a rather lesser extent, in the asymmetric configuration, which then requires a stronger damping action in the supports.
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Ding, Shuye, Jianfeng Liu, and Liying Zhang. "Fan characteristics of the self-support components of rotor ends and its performance matching." International Journal of Heat and Mass Transfer 108 (May 2017): 1917–23. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2016.12.005.
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Melkias, Alvera Apridalianti, Indriyani Indriyani, and Fachry Fadian. "Analisis Kerusakan pada Rotor Pompa Sentrifugal G-1-12-C di PT X." Jurnal Surya Teknika 11, no. 2 (2024): 585–92. https://doi.org/10.37859/jst.v11i2.8300.
Full textAbstract:
Damage to a tool can cause the production process to stop and cause downtime. Preventing damage to equipment is by managing the maintenance process. This process includes preventive maintenance, corrective maintenance and predictions of damage (predictive maintenance) which is carried out periodically. Centrifugal pumps have the working principle of converting kinetic energy (speed) of liquid into potential (dynamic) energy through an impeller that rotates in the casing. This pump is an impeller that is mounted on a shaft with bearings at both ends. Damage to the pump rotor has a serious impact on the performance and reliability of the pump system. The rotor is one of the main components responsible for transferring mechanical energy into the pumped fluid, so damage to the rotor can affect pump efficiency, operational life, and damage to pump components. Analysis of damage to the pump rotor was carried out by testing using the NDT method. NDT testing includes Visual Inspection, Magnetic Particle Inspection, Liquid Penetrant and Balancing Rotor. Based on the results of the tests and analysis carried out, it was found that there was damage to several parts of the pump rotor, such as corrosion on the pump shaft, dirt on the surface, and scratches on the mechanical seal seat area with a depth of approximately 0.50 mm. Rotor unbalance or the center of gravity of the shaft rotation is not the same as the geometric center of the shaft. The impeller was found to be in poor condition, high metal of radial impeller and medium to heavy rubbing at wearing impeller. The DE and NDE distance sleeves are not in a bad condition and there are scratches.
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Lee, Yoo, Yoon, and Jang. "Advanced Fault Ride-through Strategy by an MMC HVDC Transmission for Off-Shore Wind Farm Interconnection." Applied Sciences 9, no. 12 (2019): 2522. http://dx.doi.org/10.3390/app9122522.
Full textAbstract:
In order to solve the problems brought upon by off-shore wind-power plants, it is important to improve fault ride-through capability when an on-shore fault occurs in order to prevent DC overvoltage. In this paper, a coordinated control strategy is implemented for a doubly-fed induction generator (DFIG)-based off-shore wind farm, which connects to on-shore land by a modular multilevel converter (MMC)-based high voltage direct current (HVDC) transmission system during an on-shore fault. The proposed control strategy adjusts the DC voltage of the off-shore converter to ride through fault condition, simultaneously varying off-shore AC frequency. The grid-side converter detects the frequency difference, and the rotor-side converter curtails the output power of the DFIG. The surplus energy will be accumulated at the rotor by accelerating the rotor speed and DC link by rising DC voltage. By the time the fault ends, energy stored in the rotor and energy stored in the DC capacitor will be released to the on-shore side to restore the normal transmission state. Based on the control strategy, the off-shore wind farm will ride through an on-shore fault with minimum rotor stress. To verify the validity of the proposed control strategy, a DFIG-based wind farm connecting to the on-shore side by an MMC HVDC system is simulated by PSCAD with an on-shore Point of Common Coupling side fault scenario.
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Neilson, R. D., and A. D. S. Barr. "Dynamics of a Rigid Rotor Mounted on Discontinuously Non-Linear Elastic Supports." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 202, no. 5 (1988): 369–76. http://dx.doi.org/10.1243/pime_proc_1988_202_135_02.
Full textAbstract:
The equations of motion of a rigid rotor mounted at both ends in discontinuously non-linear supports and subject to excitation by arbitrary imbalance are presented. The methods used to solve the equations are described briefly and the responses obtained from the model and an experimental rig are discussed and compared. Good correlation is found. Over a range of shaft speed the presence of aperiodic responses characterized by spectral sidebands which diverge with increasing shaft speed is noted. An explanation of the mechanism generating these sidebands is advanced.
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Кибальний, Михайло Юрійович, Андрій Павлович Дьомін, Сергій Олександрович Дегтяренко та Микола Іванович Москаленко. "Розрахункове дослідження аеродинамічних характеристик рульового гвинта вертольота типу Мі-8 з урахуванням інтерференції з несучим гвинтом на режимі висіння при боковому вітрі". Aerospace technic and technology, № 2 (28 квітня 2021): 28–35. http://dx.doi.org/10.32620/aktt.2021.2.04.
Full textAbstract:
Under certain conditions of a helicopter flight, the main rotor can exert a rather strong effect on the tail rotor, changing its traction and power characteristics. The calculated and experimental characteristics of an isolated tail rotor under such operating conditions can differ significantly from those under conditions of interaction with the main rotor. The study of this phenomenon is an urgent task, since a change in the characteristics of the tail rotor and the conditions of its operation in the presence of the main rotor can cause a decrease in controllability margins and, as a consequence, the cause of an aircraft accident, for example, the so-called. "left rotation" of the helicopter. Since 1985, on helicopters from M. L. Mile, 42 aviation accidents occurred in units and subdivisions of the state and civil aviation of the USSR (and now Russia) due to helicopters falling into spontaneous left rotation. Over the past 10 years, 29 accidents (8 accidents and 21 accidents) have occurred for this reason. 29 helicopters were lost: 20 Mi-8, 5 Mi-24, 4 Mi-2. Experience shows that getting into an uncontrolled left rotation in almost 100% of cases ends with a collision of the helicopter with the ground and overturning it on the starboard side. The interaction of the main and tail rotor is most significantly manifested in the modes of horizontal flight with sliding at low speeds and hovering in crosswind conditions. This is due to the peculiarities of the formation of the main rotor vortex wake. In this article, the case of aerodynamic interference of the main rotor and several helicopter configurations in horizontal flight mode with the low speed with sliding (hovering in a crosswind) is considered. Using the methods of computational fluid dynamics, the degree of influence of the main rotor on the tail rotor was investigated in the described modes. The most severe operating modes of the tail rotor of each configuration have been determined. Based on the results of calculations, the most rational configuration of the tail rotor has been chosen, which has the greatest reserves of controllability under unfavorable operating conditions. The results obtained have been used in the design of a new perspective helicopter, modernization of the existing fleet, as well as improving the flight safety level.
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Khalid, Asad A., A. Albagul, W. Faris, and Godem A. Ismail. "An Experimental Study on Steel and Teflon Squeeze Film Dampers." Shock and Vibration 13, no. 1 (2006): 33–40. http://dx.doi.org/10.1155/2006/387302.
Full textAbstract:
In this paper, the vibration analysis on Teflon and steel squeeze film dampers has been carried out. At different frequency ranges, vibration amplitude and the resonance frequency are measured. The eccentricity ratio at resonance speed has been determined. Results show that the vibration amplitude of the steel damper is 10% less at resonance compared with the Teflon damper. On the other hand, saving weight of 36% has been achieved by using the Teflon damper.A rotor bearing system for vibration analysis has been designed and fabricated. The test rig consists of mild steel shaft with two supports, oil pressure gauge system and two self-alignment ball bearings fixed on each end support. Two squeeze film dampers are used at each of the rotor support ends. Teflon and steel squeeze film dampers (SFD) were fabricated and tested using turning machine.
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Melani, PF, F. Balduzzi, and A. Bianchini. "Simulating tip effects in vertical-axis wind turbines with the actuator line method." Journal of Physics: Conference Series 2265, no. 3 (2022): 032028. http://dx.doi.org/10.1088/1742-6596/2265/3/032028.
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Abstract Simulation of the complex, unsteady aerodynamics characterizing Darrieus rotors requires computational tools with a fidelity higher than the ubiquitous Blade Element Momentum (BEM) theory. Among them, the Actuator Line Method (ALM) stands out in terms of accuracy and computational cost. This approach, however, still fails to resolve the vortex-like structures shed at the blade ends, overestimating turbine performance at the higher rotational speeds. Moving from this background, in this study a comprehensive investigation on the ALM’s capability to simulate tip effects and their impact on rotor performance is carried out. To this end, the ALM tool developed by the authors in the ANSYS® FLUENT® environment (v. 20.2) and specifically tailored to the simulation of vertical-axis machines was employed. Both a steady finite wing and a fictitious one-blade Darrieus H-rotor, for which high-fidelity blade-resolved CFD data are available as benchmark, were considered as test cases. ALM simulations were first performed without any correction for different cell sizes and force projection radii, so that the limits of the original approach could be assessed. Then, two different sub-models were applied: the classical semi-empirical Glauert correction and a new methodology based on the Lifting Line Theory (LLT), which was recently proposed by Dağ and Sørensen (DS). The latter was here adapted to vertical-axis machines. Eventually, the blade spanwise load profiles coming from the three approaches were assessed and compared, proving the superior performance of the DS model.
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Annenkov, A. N., S. V. Sizikov, and A. I. Shiyanov. "ASYNCHRONOUS MOTOR WITH A HOLLOW PERFORATED ROTOR." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 61, no. 2 (2018): 129–40. http://dx.doi.org/10.21122/1029-7448-2018-61-2-129-140.
Full textAbstract:
The paper presents a brief analysis of the conducted researches of the asynchronous executive motors and the induction motor, as well as the design of the asynchronous executive motor with a hollow perforated rotor. The basic relationships for determining the geometry of the rotor that directly influences the energy performance of the electric machine are also presented. The calculations to determine the geometry of the windows, located within a part of the active length of the stator package in the zone adjacent to the solid frontal area of the surface of the barrel from the side of its end face that is opposite to the bottom of the rotor barrel. In an asynchronous motor with a hollow perforated rotor improvement of energy performance (increase of maximum torque, efficiency and cosj of the engine) is achieved. These advantages are provided by the fact that the windows in the hollow rotor barrel are located within the part of the active length of the stator package in the zone adjacent to the solid frontal section of the rotor barrel surface on its end face that is opposite to the bottom of the barrel. In accordance with the design of the hollow rotor, the bottom of the barrel of one of the ends acts as superconducting short-circulating ring, therefore the ratio of increase in resistance (caused by the transverse edge effect) depends on the distribution of the rotor currents in the area adjacent to the solid frontal portion of the surface of the barrel on end that is opposite to the bottom of the barrel. In the analysis of current density distribution in a hollow rotor with the axial length L', all electric constant and geometric dimensions that are taken into account in the calculation are known values. Arbitrarily set constants are the primary currents and the rotational frequency of the rotor. With the rotation speed increase, due to the presence of the windows on one end face of the rotor and to the impact of the bottom of the barrel on the other one, the elementary currents of the rotor within the active length of the machine boring would be directed mainly in the axial direction, including the cases of comparatively small slippage that corresponds to the small frequency of the alternating magnetization of the rotor material. I. e. a certain part of the active surface of the rotor on the end that is opposite to the bottom of its barrel would not function as the frontal part of the winding while reducing the frequency of currents in the rotor material. This provides an increase in the active component of the rotor current that is proportional to the electromagnetic torque of the motor. Correspondingly, the frontal parts of equivalent winding of the hollow rotor (through which the currents do not generate torque) would not be spread at high rotational speeds to the area of the active length of the machine.
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Hu, Tian, Yan Li, and Ren Yuan Tang. "Calculation of 3D Fluid Flow Field and Thermal Field of Air-Cooled Medium Motor." Applied Mechanics and Materials 513-517 (February 2014): 3468–71. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.3468.
Full textAbstract:
For a medium air-cooled asynchronous motor, the physical model of cooling air inside the motor was established to research the air flow distribution and characteristics of the internal flow of the medium motor. By the finite volume method according to the computational fluid mechanics (CFD) principle, the three-dimensional turbulent flow field in computational domain was simulated numerically using boundary conditions of the pressure inlet and outlet obtained from engineering calculations. From the result, the thermal field of stator and rotor was calculation. The results show that the wind speed of cooling air duct which near the both ends was higher than the middle. It causes the temperature of the motor which near the both ends was lower than the middle part. The maximum temperature rise of the motor appear in the middle of the upper windings, and the specific value was 74K.
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Baskharone, E. A., and S. J. Hensel. "Flow Field in the Secondary, Seal-Containing Passages of Centrifugal Pumps." Journal of Fluids Engineering 115, no. 4 (1993): 702–9. http://dx.doi.org/10.1115/1.2910202.
Full textAbstract:
This paper illustrates the impact of seal configuration on the through-flow leakage in centrifugal pumps with shrouded impellers. The flow model is based on the Petrov-Galerkin finite element method, and the computational domain permits the primary/secondary flow interaction at both ends of the clearance gap. The model is applied to a hydraulic pump with two different seal configurations for the purpose of comparison. The computed results show a strong dependency of the leakage flow percentage and swirl-velocity retention on the overall shape of the shroud-to-housing passage including, in particular, the seal geometry. The results are generally consistent with documented observations and measurements in similar pump stages. From a rotordynamic standpoint, the current computational model conceptually provides the centered-rotor “zeroth-order” flow field for existing perturbation models of fluid/rotor interaction. The flow model is applied to two different secondary passage configurations of a centrifugal pump, and the results used in interpreting existing rotordynamic data concerning the same passage configurations.
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Yang, Chen, Wei Cai, and Baicheng Shao. "Optimization of rotational oil-spray-cooling structure and temperature field analysis of PMSM in vehicle." Thermal Science, no. 00 (2024): 171. http://dx.doi.org/10.2298/tsci240330171y.
Full textAbstract:
The heat dissipation of the permanent magnet synchronous motor (PMSM) of an electric vehicle is always worthy of attention, and the design of the cooling system of the PMSM is very important. The rotor rotational oil-spray-cooling structure is widely used in PMSM with hairpin winding. The oil enters from one side of the hollow shaft and is sprayed from the outlets of the front and rear, respectively, which realizes the cooling of the winding at both ends. However, the flow difference on both sides of the shaft will cause the problem of uneven cooling of the winding and the issue of local overheating of the motor. Therefore, the hollow shaft structure needs to be optimized. A 120 kW oil-cooled motor is analyzed as an example in this paper. The flow field distribution during the rotation of the rotor and the reasons for the uneven shunt are analyzed. And the structural parameters of the hollow shaft are optimized by using the Taguchi method and the response surface method. It was found that the new shaft structure can better realize the shunt and reduce the winding and rotor temperature. It provides a guide for the design of the rotational oil-spray-cooling structure of the oil-cooling PMSM.
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Bernatt, Jakub, Stanisław Gawron, Tadeusz Glinka, and Artur Polak. "Traction induction motor." MATEC Web of Conferences 180 (2018): 04005. http://dx.doi.org/10.1051/matecconf/201818004005.
Full textAbstract:
The paper presents a traction induction motor with an innovative rotor winding design. The winding of the rotor is almost identical to the armature winding in the dc traction motors, with the exception of commutator. Winding is double layered. The bars are insulated. Along the iron core bars are secured with wedges and in the winding outhang with bandages. The bars of the bottom layer in the winding outhang part near the iron core are bent radially in the direction of the shaft axis. On the winding outhang of the bottom layer an inner bandage is applied. On the winding outhang of the top layer an outer bandage is applied. All the ends of the bottom and top layers bars, on both sides of the rotor’s core, are connected together by ferrule. There is a ring placed on the shaft or on the coil support on one side of the rotor’s core. It is best if this ring is made of copper. The ring is characterized by mp tongues, which are distributed evenly along its circumference (p is number of winding pole pairs and m is number of rotor winding phases). Tongues are connected to equally uniformly placed ferrules. Bandages are made of carbon fibre or glass fibre tape.
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Déa, Thales Henrique Gomes, Rodrigo Francisco Borges Lourenco, Rafael de Oliveira Silva, Michael Dowglas de Gois Silva, Fábio Roberto Chavarette, and Roberto Outa. "ANÁLISE DINÂMICA EXPERIMENTAL DE ROTORES DESBALANCEADOS." COLLOQUIUM EXACTARUM 13, no. 3 (2021): 13–18. http://dx.doi.org/10.5747/ce.2021.v13.n3.e365.
Full textAbstract:
Rotating machines in motion usually produce dynamic forces that diffuse to the ends that support them, such efforts can lead to disadvantageous reactions to the operation of the machine, as well as unbalance or misalignment that can damage the shaft-rotor assembly or the elements directly linked to it. The objective of this project is to develop a mechanical and experimental system that enables the testing and data acquisition of a rotating machine and build a computational algorithm to generate amplitude and velocity diagrams as a function of time and compare the dynamic behavior of a vibrational bench, in normal and unbalanced condition.
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Yang, Yu-Neng, and Wei-Hua Chieng. "An Elastic Suspension Design Framework for Tuned Gyroscopes." Journal of Mechanical Design 119, no. 1 (1997): 81–87. http://dx.doi.org/10.1115/1.2828792.
Full textAbstract:
This paper presents a design for a new tuned gyroscope framework consisting of a heavy rotor supported by a heli-flex suspension. Inherently free of 2ω drift-error, the gyro can be precisely tuned by adjusting pre-extension between two ends of its helix. The symmetrical support structure of this isotropic helical suspension design significantly reduces error moment caused by linear acceleration, and the device eliminates G2 drift by virtue of its desirable anisoelasticity characteristic. The gyro design is simple, highly manufacturable, and when appropriate suspension parameters are used, produces a long-term drift-rate of 0.01 deg./hr.
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Shabaneh, Nabeel, and Jean W. Zu. "Nonlinear Dynamic Analysis of a Rotor Shaft System With Viscoelastically Supported Bearings." Journal of Vibration and Acoustics 125, no. 3 (2003): 290–98. http://dx.doi.org/10.1115/1.1547684.
Full textAbstract:
This research investigates the dynamic analysis of a single-rotor shaft system with nonlinear elastic bearings at the ends mounted on viscoelastic suspension. Timoshenko shaft model is utilized to incorporate the flexibility of the shaft; the rotor is considered to be rigid and located at the mid-span of the shaft. A nonlinear bearing pedestal model is assumed which has a cubic nonlinear spring and linear damping characteristics. The viscoelastic supports are modeled using Kelvin-Voigt model. Free and forced vibration is investigated based on the direct multiple scales method of one-to-one frequency-to-amplitude relationship using third order perturbation expansion. The results of the nonlinear analysis show that a limiting value of the internal damping coefficient of the shaft exists where the trend of the frequency-response curve switches. Also, the primary resonance peak shifts to higher frequencies with the increase of the bearing nonlinear elastic characteristics, but with a flattened curve and hence lower peak values. A jump phenomenon takes place for high values of the bearing nonlinear elastic characteristics.
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Ämmälä, Ari. "Comparison of Pin Mill and Hammer Mill in the Fine Grinding of Sphagnum Moss." Energies 16, no. 5 (2023): 2437. http://dx.doi.org/10.3390/en16052437.
Full textAbstract:
Dried sphagnum moss was ground using a pin mill and a hammer mill under various operating conditions, i.e., changes in the rotor frequency and feed rate. The specific energy consumption of the size reduction was recorded. The ground powder was characterized by median particle size, width of size distribution (span), loose and tapped bulk densities, and the Hausner ratio. Pin milling used less energy for size reduction than hammer milling, especially when the target size was below 100 μm. In both milling methods, the specific energy consumption was mainly caused by the rotor frequency used. However, in pin milling, the specific energy consumption was also dependent on the production rate: the higher the rate, the higher the energy consumption. No such dependence was observed with the hammer mill. The span was wider in pin milling than hammer milling in the intermediate product size range although the difference decreased at the fine and coarse ends. A similar pattern was found for bulk densities. However, the flowability of powder, as characterized by the Hausner ratio, was comparable between the grinding methods.
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Dhramvir, Singh*1 Nikhilesh N. Singh2 &. Dr. Prabhat Kumar Sinha3. "VIBRATION ANALYSIS AND CONTROL OF ROTATING COMPOSITE SHAFT USING ACTIVE MAGNETIC BEARINGS." INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY 6, no. 8 (2017): 378–84. https://doi.org/10.5281/zenodo.848580.
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In this article the fibre reinforced polymer (FRP) composites shaft analysed as a Timoshenko beam. The prime objective of this research to reduce the vibration in composites shaft system. To utilize the active vibration control technique. Three different isotropic rigid disks are mounted on it and they also supported by two active magnetic bearing at its ends. The analysis work involves finite element, vibrational and rotor dynamic analysis of the system. Rotary inertia effect, gyroscopic effect kinetic energy and strain energy of the shaft are derived and studied. The governing equation is obtained by applying Hamilton’s principle using finite element method in which four degrees of freedom at each node is considered. Active control scheme is applied through magnetic bearings by using a controller containing low pass filter, notch filter, sensor and amplifier which controls the current and correspondingly control the stability of the whole rotor-shaft system. Campbell diagram, stability limit speed diagram and logarithmic decrement diagram are studied to establish the system stability. Effect of different types of stacking sequences are also studied and compared.
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Colding-Jorgensen, J. "Limit Cycle Vibration Analysis of a Long Rotating Cylinder Partially Filled With Liquid." Journal of Engineering for Gas Turbines and Power 113, no. 4 (1991): 563–67. http://dx.doi.org/10.1115/1.2906278.
Full textAbstract:
The dynamics of a long, stiff cylinder, flexibly suspended at the ends, partially filled with liquid, is analyzed for varying rotating speed. It appears from the analysis that in the absence of external damping, two distinct speed ranges with unstable whirl are present, as opposed to one instability region for the short cylinder, which has been analyzed by a number of authors (Kuipers, 1964; Wolf, 1968). This is in agreement with field experience with centrifuges, where several regions of instability are often encountered, each corresponding to a particular vibration mode. The results should also apply to a jet engine with oil accidentally trapped in the rotor, or any hollow rotor with liquid trapped in the cavity. When external damping is applied the linear theory predicts the rotor to be unstable at all speeds (Kuipers, 1964). This is clearly not in accordance with field experience, and other authors have suggested different types of nonlinear analysis that can give finite amplitude stable whirl or pulsating whirl (Berman et al., 1985). In the present analysis a simplified nonlinear analysis known as the hydraulic jump approximation is applied in the two unstable speed ranges predicted by the linear theory, and a stable whirl finite amplitude, dependent on the external damping, follows. It is argued that the amplitudes found this way should always be higher than those predicted by a more sophisticated analysis, and also higher than the amplitudes measured by other authors, so that the procedure described should give a safe worst case prediction of rotor whirl amplitudes for a given external damping. Finally, an experimental setup intended to verify the analysis in a quantitative way is presented.
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Ding, Q., and A. Y. T. Leung. "Numerical and Experimental Investigations on Flexible Multi-bearing Rotor Dynamics." Journal of Vibration and Acoustics 127, no. 4 (2004): 408–15. http://dx.doi.org/10.1115/1.1898336.
Full textAbstract:
An experimental test rig is built to verify the dynamics of a multi-bearing rotor. It consists of two flexibly coupled shafts and is connected to a motor at one end via a flexible coupling. Each of the shafts is supported at the ends by two hydrodynamic bearings and is attached with two disks with equal and unequal masses, respectively. The mathematical model of the test rig is developed and is simulated numerically. The non-stationary dynamic responses of the system during speed-up with a constant angular acceleration are shown, respectively, by the non-stationary bifurcation diagrams, the selected time flows, and the spectrum cascades. Experiments are then carried out on the test rig. Generally, the numerical results are verified qualitatively by the experiments. Both results indicate that the non-synchronous whirls of the two shafts influence each other when flexibly coupled together. In particular, a new phenomenon is found for the four-bearing rotor system: the pre-existing non-synchronous whirl/whip resulted from the instability of one shaft can activate the onset of oil instability of another shaft. In the theoretical simulation, this phenomenon represents the rapid increase of the non-synchronous whirl orbit, whereas in the experiment, it represents the simultaneous existence of two whirl/whip frequencies in the spectra.
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Li, Weili, Junci Cao, Dong Li, and Zhigang Wu. "Study on Heat Exchange of Different Ventilation Structures of Asynchronous Traction Motor for High Speed EMU." Transportation Systems and Technology 5, no. 2 (2019): 16–30. http://dx.doi.org/10.17816/transsyst20195216-30.
Full textAbstract:
Background: Aiming at the problems of high local temperature and uneven temperature distribution in asynchronous traction motor of high-speed Electric Multiple Unit (EMU) when it is running.
 Aim: In this paper, the influence of ventilation system with different structure on temperature distribution is studied.
 Methods: Taking 600kW asynchronous traction motor as an example, the electromagnetic-fluid-temperature analysis model of the traction motor is established, and the temperature values of different positions in the motor are obtained.
 The accuracy of the calculation results is verified by comparing with the actual measurement.
 On this basis, by adjusting the structure of stator and rotor axial ventilation holes, the relationship between temperature distribution and fluid flow state in motor is studied.
 In addition, the influence of fluid incidence angle on fluid velocity and heat dissipation performance of motor is also studied, and the ventilation structure scheme with relative balance of axial and circumferential temperature in motor is found out, which provides a reference strategy for the design of temperature rise of motor with forced ventilation structure.
 Results: The wind speed near the intake side of stator teeth and rotor teeth groove is less than that far from the intake side. The flow distribution trend of rotor vent is similar to that of stator vent, but the air in the groove is affected by centrifugal force of rotor rotation, which makes the wind speed difference on the intake side larger than that on the outlet side.
 The stator winding and rotor guide bar are affected by wind temperature to reach the maximum temperature at the end of the outlet respectively. The stator core is higher at the windward side and the leeward side than the other parts of the motor. The heat dissipation effect at both ends is good.
 The highest temperature of the stator core appears near the leeward side.