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1
Reinmo¨ller, U., B. Stephan, S. Schmidt i R. Niehuis. "Clocking Effects in a 1.5 Stage Axial Turbine—Steady and Unsteady Experimental Investigations Supported by Numerical Simulations". Journal of Turbomachinery 124, nr 1 (1.02.2001): 52–60. http://dx.doi.org/10.1115/1.1425811.
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The interaction between rotor and stator airfoils in a multistage turbomachine causes an inherently unsteady flow field. In addition, different relative circumferential positions of several stator rows and rotor rows, respectively, have an influence on the flow behavior in terms of loss generation, energy transport and secondary flow. The objective of the presented study is to investigate the effects of stator airfoil clocking on the performance of a 1-1/2 stage axial cold air turbine. The investigated axial turbine consists of two identical stators. The low aspect ratio of the blades and their prismatic design leads to a three-dimensional outlet flow with a high degree of secondary flow phenomena. Nevertheless, the small axial gaps between the blade rows are responsible for strong potential flow interaction with the radial wake regions in the measurement planes. Consequently, parts of the wakes of the first stator are clearly detected in the rotor outlet flow. To give an overview of the time-averaged flow field, measurements with pneumatic probes are conducted behind each blade row at ten different clocking-positions of the second stator. Further, an optimized clocking position was found due to a minimum in pressure loss behind the second stator. The unsteady measurements are carried out with hot-wire probes for three selected stator-stator positions. Animations of selected flow properties show the influence of different circumferential positions of the second stator on the unsteady flow behavior and secondary flow field. In addition and compared with experimental results three-dimensional unsteady viscous flow computations are performed.
2
Tomasello, Stella Grazia, Roberto Meloni, Luca Andrei i Antonio Andreini. "Study of Combustor–Turbine Interactions by Performing Coupled and Decoupled Hybrid RANS-LES Simulations under Representative Engine-like Conditions". Energies 16, nr 14 (15.07.2023): 5395. http://dx.doi.org/10.3390/en16145395.
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Combustion–turbine interaction phenomena are attracting ever-growing interest in recent years. As a matter of fact, the strong unsteady and three-dimensional flow field that characterizes the combustor is usually conserved up to the first-stage nozzle, possibly affecting its design and performance in terms of aerodynamics and the effectiveness of the cooling system as well. Such conditions are also exacerbated by the employment of lean-burn combustors, where high turbulence levels are required for the flame stabilization, resulting in even greater temperature and velocity distortions at the inlet of the first-stage nozzle. Even if it has been proven by several past studies that the best way of studying the combustor–turbine interaction is simulating the two components together, performing coupled simulations is still challenging from a numerical point of view, especially in an industrial context. For this reason, the application and generation of the most representative and reliable boundary conditions possible at the inlet of the S1N have assumed an increased importance in order to study the two components separately by performing decoupled simulations. In this context, the purpose of the present work is to compare fully integrated combustor–stator SBES simulations to isolated stator ones. To perform the stator-only calculations, the fully unsteady inlet conditions of the stator have been recorded at the interface plane between the two components in the integrated SBES simulation and then they have been reconstructed by applying the proper orthogonal decomposition (POD) technique. The SBES simulations of the isolated stator have been so performed with the aim of determining whether the flow field obtained is comparable with the one of the integrated simulation, thus allowing more realistic results to be obtained rather than imposing time-averaged 2D maps, as per standard design practice.
3
Wang, Ziwei, Xiong Jiang, Ti Chen, Yan Hao i Min Qiu. "Numerical simulation of transonic compressor under circumferential inlet distortion and rotor/stator interference using harmonic balance method". Modern Physics Letters B 32, nr 12n13 (10.05.2018): 1840021. http://dx.doi.org/10.1142/s0217984918400213.
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Simulating the unsteady flow of compressor under circumferential inlet distortion and rotor/stator interference would need full-annulus grid with a dual time method. This process is time consuming and needs a large amount of computational resources. Harmonic balance method simulates the unsteady flow in compressor on single passage grid with a series of steady simulations. This will largely increase the computational efficiency in comparison with the dual time method. However, most simulations with harmonic balance method are conducted on the flow under either circumferential inlet distortion or rotor/stator interference. Based on an in-house CFD code, the harmonic balance method is applied in the simulation of flow in the NASA Stage 35 under both circumferential inlet distortion and rotor/stator interference. As the unsteady flow is influenced by two different unsteady disturbances, it leads to the computational instability. The instability can be avoided by coupling the harmonic balance method with an optimizing algorithm. The computational result of harmonic balance method is compared with the result of full-annulus simulation. It denotes that, the harmonic balance method simulates the flow under circumferential inlet distortion and rotor/stator interference as precise as the full-annulus simulation with a speed-up of about 8 times.
4
Akwa, J. V., i A. P. Petry. "STATORS USE INFLUENCE ON THE PERFORMANCE OF A SAVONIUS WIND ROTOR USING COMPUTATIONAL FLUID DYNAMICS". Revista de Engenharia Térmica 10, nr 1-2 (31.12.2011): 63. http://dx.doi.org/10.5380/reterm.v10i1-2.61965.
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This paper aims at verifying the influence of using five kinds of stators in the averaged moment and power coefficients of a Savonius wind rotor using computational fluid dynamics (CFD). The analyzed stators have cylindrical shape with two and three openings, one and four deflector blades and walls shaped like a wings. The equations of continuity, Reynolds Averaged Navier-Stokes – RANS and the Eddy Viscosity Model k-ω SST, in its Low-Reynolds approaches, with hybrid near wall treatment; are numerically solved using the commercial software Star-CCM+, based on Finite Volume Method, resulting in the fields of pressure and velocity of the flow and the forces acting on the rotor buckets. The moment and power coefficients are achieved through integration of forces coming from the effects of pressure and viscosity of the wind on the buckets device. The influence of the stators use in the moment and power coefficients is checked by changing the geometry of the device for each simulations series, keeping the Reynolds number based on rotor diameter equal to 433,500. The obtained values for averaged moment and power coefficients indicate that for each type of stator used, there was maximum performance for a given tip speed ratio of rotor. Improvement in performance over the operation without stator was obtained only to the operations using stator with four deflector blades and to the stator with cylindrical shape with three openings. The improvement percentage in performance obtained for the best condition (use of four deflector blades at tip speed ratio equal to 1) is 12% compared to the performance of the rotor operating without stator.
5
Tang, Jing, Jie Chen, Kan Dong, Yongheng Yang, Haichen Lv i Zhigang Liu. "Modeling and Evaluation of Stator and Rotor Faults for Induction Motors". Energies 13, nr 1 (26.12.2019): 133. http://dx.doi.org/10.3390/en13010133.
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The modeling of stator and rotor faults is the basis of the development of online monitoring techniques. To obtain reliable stator and rotor fault models, this paper focuses on dynamic modeling of the stator and rotor faults in real-time, which adopts a multiple-coupled-circuit method by using a winding function approach for inductance calculation. Firstly, the model of the induction machine with a healthy cage is introduced, where a rotor mesh that consists of a few rotor loops and an end ring loop is considered. Then, the stator inter-turn fault model is presented by adding an extra branch with short circuit resistance on the fault part of a stator phase winding. The broken rotor bar fault is then detailed by merging and removing the broken-bar-related loops. Finally, the discrete models under healthy and faulty conditions are developed by using the Tustin transformation for digital implementation. Moreover, the stator and rotor mutual inductances are derived as a function of the rotor position according to the turn and winding functions distribution. Simulations and experiments are performed on a 2.2-kW/380-V/50-Hz three-phase and four-pole induction motor to show the performance of the stator and rotor faults, where the saturation effect is considered in simulations by exploiting the measurements of a no load test. The simulation results are in close agreement with the experimental results. Furthermore, magnitudes of the characteristic frequencies of 2f1 in torque and (1 ± 2s)f1 in current are analyzed to evaluate the stator and rotor fault severity. Both indicate that the stator fault severity is related to the short circuit resistance. Further, the number of shorted turns and the number of continuous broken bars determines the rotor fault severity.
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Karanayil, Baburaj, Muhammed Fazlur Rahman i Colin Grantham. "Identification of Induction Motor Parameters in Industrial Drives with Artificial Neural Networks". Advances in Fuzzy Systems 2009 (2009): 1–10. http://dx.doi.org/10.1155/2009/241809.
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This paper presents a new method of online estimation of the stator and rotor resistance of the induction motor in the indirect vector-controlled drive, with artificial neural networks. The back propagation algorithm is used for training of the neural networks. The error between the rotor flux linkages based on a neural network model and a voltage model is back propagated to adjust the weights of the neural network model for the rotor resistance estimation. For the stator resistance estimation, the error between the measured stator current and the estimated stator current using neural network is back propagated to adjust the weights of the neural network. The performance of the stator and rotor resistance estimators and torque and flux responses of the drive, together with these estimators, is investigated with the help of simulations for variations in the stator and rotor resistance from their nominal values. Both types of resistance are estimated experimentally, using the proposed neural network in a vector-controlled induction motor drive. Data on tracking performances of these estimators are presented. With this approach, the rotor resistance estimation was found to be insensitive to the stator resistance variations both in simulation and experiment.
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Rai, M. M., i N. K. Madavan. "Multi-Airfoil Navier–Stokes Simulations of Turbine Rotor–Stator Interaction". Journal of Turbomachinery 112, nr 3 (1.07.1990): 377–84. http://dx.doi.org/10.1115/1.2927670.
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An accurate numerical analysis of the flows associated with rotor–stator configurations in turbomachinery can be extremely helpful in optimizing the performance of turbomachinery. In this study the unsteady, thin-layer, Navier–Stokes equations in two spatial dimensions are solved on a system of patched and overlaid grids for an axial-turbine rotor–stator configuration. The governing equations are solved using a finite-difference, upwind algorithm that is set in an iterative, implicit framework. Results are presented in the form of pressure contours, time-averaged pressures, unsteady pressures, amplitudes, and phase. The numerical results are compared with experimental data and the agreement is found to be good. The results are also compared with those of an earlier study, which used only one rotor and one stator airfoil. The current study uses multiple rotor and stator airfoils and a pitch ratio that is much closer to the experimental ratio. Consequently, the results of this study are found to be closer to the experimental data.
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Hembera, M., H. P. Kau i E. Johann. "Simulation of Casing Treatments of a Transonic Compressor Stage". International Journal of Rotating Machinery 2008 (2008): 1–10. http://dx.doi.org/10.1155/2008/657202.
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This article presents the study of casing treatments on an axial compressor stage for improving stability and enhancing stall margin. So far, many simulations of casing treatments on single rotor or rotor-stator configurations were performed. But as the application of casing treatments in engines will be in a multistage compressor, in this study, the axial slots are applied to a typical transonic first stage of a high-pressure 4.5-stage compressor including an upstream IGV, rotor, and stator. The unsteady simulations are performed with a three-dimensional time accurate Favre-averaged Navier-stokes flow solver. In order to resolve all important flow mechanisms appearing through the use of casing treatments, a computational multiblock grid consisting of approximately 2.4 million nodes was used for the simulations. The configurations include axial slots in 4 different variations with an axial extension ranging into the blade passage of the IGV. Their shape is semicircular with no inclination in circumferential direction. The simulations proved the effectiveness of casing treatments with an upstream stator. However, the results also showed that the slots have to be carefully positioned relative to the stator location.
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Xu, Jieqiong, Qunhong Li i Shimin Wang. "Impulsive Control of the Rotor-Stator Rub Based on Phase Characteristic". Abstract and Applied Analysis 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/495747.
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An impulsive control method is proposed to eliminate the rotor-stator rubbing based on the phase characteristic. The relation between the vibration energy and the phase difference suggests the starting point for controlling the rotor-stator rubbing by implementing impulse. When the contact between the rotor and the stator occurs, the impulse is implemented inx-direction andy-direction several times to avoid the rotor-stator rubbing. The practical feasibility of this approach is investigated by numerical simulations.
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Valkov, T. V., i C. S. Tan. "Effect of Upstream Rotor Vortical Disturbances on the Time-Averaged Performance of Axial Compressor Stators: Part 1—Framework of Technical Approach and Wake–Stator Blade Interactions". Journal of Turbomachinery 121, nr 3 (1.07.1999): 377–86. http://dx.doi.org/10.1115/1.2841330.
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In a two-part paper, key computed results from a set of first-of-a-kind numerical simulations on the unsteady interaction of axial compressor stators with upstream rotor wakes and tip leakage vortices are employed to elucidate their impact on the time-averaged performance of the stator. Detailed interrogation of the computed flow field showed that for both wakes and tip leakage vortices, the impact of these mechanisms can be described on the same physical basis. Specifically, there are two generic mechanisms with significant influence on performance: reversible recovery of the energy in the wakes/tip vortices (beneficial) and the associated nontransitional boundary layer response (detrimental). In the presence of flow unsteadiness associated with rotor wakes and tip vortices, the efficiency of the stator under consideration is higher than that obtained using a mixed-out steady flow approximation. The effects of tip vortices and wakes are of comparable importance. The impact of stator interaction with upstream wakes and vortices depends on the following parameters: axial spacing, loading, and the frequency of wake fluctuations in the rotor frame. At reduced spacing, this impact becomes significant. The most important aspect of the tip vortex is the relative velocity defect and the associated relative total pressure defect, which is perceived by the stator in the same manner as a wake. In Part 1, the focus will be on the framework of technical approach, and the interaction of stator with the moving upstream rotor wakes.
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Fernandez Oro, Jesús Manuel, Andrés Meana-Fernández, Monica Galdo Vega, Bruno Pereiras i José González Pérez. "LES-based simulation of the time-resolved flow for rotor-stator interactions in axial fan stages". International Journal of Numerical Methods for Heat & Fluid Flow 29, nr 2 (4.02.2019): 657–81. http://dx.doi.org/10.1108/hff-10-2017-0421.
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Purpose The purpose of this paper is the development of a CFD methodology based on LES computations to analyze the rotor–stator interaction in an axial fan stage. Design/methodology/approach A wall-modeled large eddy simulation (WMLES) has been performed for a spanwise 3D extrusion of the central section of the fan stage. Computations were performed for three different operating conditions, from nominal (Q_N) to off-design (85 per cent Q_N and 70 per cent Q_N) working points. Circumferential periodic conditions were introduced to reduce the extent of the computational domain. The post-processing procedure enabled the segregation of unsteady deterministic features and turbulent scales. The simulations were experimentally validated using wake profiles and turbulent scales obtained from hot-wire measurements. Findings The transport of rotor wakes and both wake–vane and wake–wake interactions in the stator flow field have been analyzed. The description of flow separation, particularly at off-design conditions, is fully benefited from the LES performance. Rotor wakes impinging on the stator vanes generate a coherent large-scale vortex shedding at reduced frequencies. Large pressure fluctuations in the stagnation region on the leading edge of the vanes have been found. Research limitations/implications LES simulations have shown to be appropriate for the assessment of the design of an axial fan, especially for specific operating conditions for which a URANS model presents a lower performance for turbulence description. Originality/value This paper describes the development of an LES-based simulation to understand the flow mechanisms related to the rotor–stator interaction in axial fan stages.
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Wellborn, S. R., i T. H. Okiishi. "The Influence of Shrouded Stator Cavity Flows on Multistage Compressor Performance". Journal of Turbomachinery 121, nr 3 (1.07.1999): 486–97. http://dx.doi.org/10.1115/1.2841341.
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Experiments were performed on a low-speed multistage axial-flow compressor to assess the effects of shrouded stator cavity flows on aerodynamic performance. Five configurations, which involved systematic changes in seal-tooth leakage rates and/or elimination of the shrouded stator cavities, were tested. Rig data indicate increasing seal-tooth leakage substantially degraded compressor performance. For every 1 percent increase in seal-tooth clearance-to-span ratio, the decrease in pressure rise was 3 percent and the reduction in efficiency was 1 point. These observed performance penalties are comparable to those commonly reported for rotor and cantilevered stator tip clearance variations. The performance degradation observed with increased leakage was brought about in two distinct ways. First, increasing seal-tooth leakage directly spoiled the near-hub performance of the stator row in which leakage occurred. Second, the altered stator exit flow conditions, caused by increased leakage, impaired the performance of the next downstream stage by decreasing the work input of the rotor and increasing total pressure loss of the stator. These trends caused the performance of downstream stages to deteriorate progressively. Numerical simulations of the test rig stator flow field were also conducted to help resolve important fluid mechanic details associated with the interaction between the primary and cavity flows. Simulation results show that fluid originating in the upstream cavity collected on the stator suction surface when the cavity tangential momentum was low and on the pressure side when it was high. The convection of cavity fluid to the suction surface was a mechanism that reduced stator performance when leakage increased.
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Andrada, Pere, Balduí Blanqué, Marcel Torrent i Pol Kobeaga. "Segmented Stator Switched Reluctance Motor Drive for Light Electric Vehicle". International Journal of Electrical and Computer Engineering Research 3, nr 1 (15.03.2023): 18–23. http://dx.doi.org/10.53375/ijecer.2023.321.
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The world market of electric light vehicles will significantly increase in the coming years. What will require the development of better high-performance drives with lowcost, and, if possible, free of permanent magnets. A segmented stator switched reluctance motor is presented to fulfill this objective because it has advantages over the conventional switched reluctance machines, such as segmented stator construction, stator shorter flux paths without flux reversal, and as a consequence, fewer iron losses. Simulations will demonstrate that the proposed segmented stator switched reluctance motor drive is suitable as a powertrain for light electric vehicles.
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Ibrahim, Issah, Mohammad Hossain Mohammadi, Vahid Ghorbanian i David Lowther. "Correlating structural complexity and acoustic noise performance of electric motors". COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 41, nr 3 (29.03.2022): 925–37. http://dx.doi.org/10.1108/compel-03-2021-0094.
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Purpose Acoustic noise is a crucial performance index in the design of electrical machines. Due to the challenges associated with modelling a complete motor, the stator is often used to estimate the sound power in the prototyping stage. While this approach greatly reduces lengthy simulations, the actual sound power of the motor may not be known. But, from the acoustic noise standpoint, not much is known about the correlation between the stator and complete motor. This paper, therefore, aims to use the sound pressure levels of the stator and the full motor to investigate the existence of correlations in the interior permanent magnet synchronous motor. Design/methodology/approach A multiphysics simulation framework is proposed to evaluate the sound pressure levels of multiple motor geometries in a given design space. Then, a statistical analysis is performed on the calculated sound pressure levels of each geometry over a selected speed range to compare the correlation strength between the stator and the full model. Findings It was established that the stator and the complete motor model are moderately correlated. As such, a reliance on the stator sound power for design and optimization routines could yield inaccurate results. Originality/value The main contribution involves the use of statistical tools to study the relationship between sound pressure levels associated with the stator geometry and the complete electric motor by increasing the motor sample size to capture subtle acoustic correlation trends in the design space of the interior permanent magnet synchronous motor.
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Oumar, Aichetoune, Yarba Ahmed i Mohamed Cherkaoui. "Operating of DSIM without Current and Speed Sensors Controlled by ADRC Control". Mathematical Problems in Engineering 2022 (1.08.2022): 1–8. http://dx.doi.org/10.1155/2022/9033780.
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This paper presents an operation of the double start induction machine (DSIM) without current and speed sensors controlled by active disturbance rejection control (ADRC). The operation of the machine, without current and speed sensors, is an economic and simple method. The main advantages of this method are the reconstruction of stator current phases and rotor speed using only one DC voltage. The method is very simple and effective. It is based on the information provided by a DC voltage and the switching states of the converters to reconstruct the stator voltages. After we use two voltages observers to estimate the current stator and the rotor speed. The performance and the effectiveness of this method are verified under different conditions of simulations in MATLAB/Simulink. The results of the simulation prove the ability of this method to produce the same performances of DSIM with the current and speed sensors.
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Haghgooei, Peyman, Ehsan Jamshidpour, Adrien Corne, Noureddine Takorabet, Davood Arab Khaburi, Lotfi Baghli i Babak Nahid-Mobarakeh. "A Parameter-Free Method for Estimating the Stator Resistance of a Wound Rotor Synchronous Machine". World Electric Vehicle Journal 14, nr 3 (4.03.2023): 65. http://dx.doi.org/10.3390/wevj14030065.
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This paper presents a new online method based on low frequency signal injection to estimate the stator resistance of a Wound Rotor Synchronous Machine (WRSM). The proposed estimator provides a parameter-free method for estimating the stator resistance, in which there is no need to know the values of the parameters of the machine model, such as the stator and rotor inductances or the rotor flux linkage. In this method, a low frequency sinusoidal current is injected in the d axis of the stator current to produce a sinusoidal flux in the stator. In this paper, it is shown that the phase difference between the generated sinusoidal flux and the injected sinusoidal current is related to the stator resistance mismatch. Using this phase difference, the stator resistance is estimated. To validate the proposed model-free estimator, simulations were performed with Matlab Simulink and the results were compared with the extended Kalman filter observer. Finally, experimental tests, under different conditions, were performed to estimate the stator resistance of a WRSM.
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Ghimire, Saugat, i Mark Turner. "Detailed Simulations of a Three-Stage Supercritical Carbon Dioxide Axial Compressor with a Focus on the Shrouded Stator Cavities Flow". Processes 11, nr 5 (28.04.2023): 1358. http://dx.doi.org/10.3390/pr11051358.
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This paper describes the findings of detailed simulations performed to investigate the impact of seal teeth cavity leakage flow on the aerodynamic and thermal performance of a three-stage supercritical CO2 axial compressor. The study compares a shrouded stator configuration (with cavities) to a cantilevered stator configuration (without cavities) to highlight their differences. High-fidelity computational fluid dynamics simulations were performed using non-linear harmonic (NLH) and mixing plane assumptions, considering various possible rotor/stator interface configurations for mixing plane calculations. The key performance parameters for each case were compared, and the best-performing configuration selected for further analysis. The individual stage performance parameters are also examined and compared between the cantilevered and shrouded configurations. It was observed that in the shrouded case, the leakage flow enters the cavity downstream of the stator trailing edge and gets entrained into the primary flow upstream of the stator, leading to boundary layer changes at the hub and degradation of stator and downstream rotor performance. Vortical flow structures were also observed in the stator wells, which tended to change the flow angles around the region, thereby affecting mixing and velocity distribution, resulting in a slight deterioration of compressor performance. Additionally, the study examines windage heating due to shear work from rotating walls, including the seal teeth surface. The amount of shear work done on the leakage flow and the corresponding rise in fluid temperature were quantified, tabulated, and further compared with a simple analytical model, showing good agreement between them and, hence, validating the numerical approach used.
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Ayas, Mehmet, Jan Skocilas i Tomas Jirout. "Analysis of Power Input of an In-Line Rotor-Stator Mixer for Viscoplastic Fluids". Processes 8, nr 8 (1.08.2020): 916. http://dx.doi.org/10.3390/pr8080916.
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In this work, the power draw and shear profile of a novel in-line rotor-stator mixer were studied experimentally and the laminar flow regime was simulated. The power draw of the rotor-stator mixer was investigated experimentally using viscoplastic shear-thinning fluid and the results of the obtained power consumptions were verified through simulations. The power draw constant and Otto-Metzner coefficient were determined from the result of experimental data and through simulations. A new method is suggested for the determination of the Otto-Metzner coefficient for the Herschel–Bulkley model and the term efficiency is introduced. It was shown that the proposed method can be applied successfully for the prediction of the Otto-Metzner coefficient for the mixing of viscoplastic shear-thinning fluids. The effect of geometry and rotor speed on power consumption and shear rate profile in the investigated mixer is discussed from the results of the simulations. It was found that numerical methods are a convenient tool and can predict the power draw of the in-line rotor-stator mixer successfully.
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Pasha, Hasan, Gil Jun Lee, Henry Zhang, Steve Hale i Santosh Kottalgi. "Automated Material Parameter Calibration for an Electric Motor Stator". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, nr 3 (1.08.2021): 3454–58. http://dx.doi.org/10.3397/in-2021-2409.
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For accurate prediction of E-motor noise and vibration performance at the design stage, it is important to model the E-Motor stator structural behavior with high fidelity. Orthotropic material properties have been widely used in practice to simulate laminated steel in the stator. In these models, material constants are calibrated to match natural frequencies of critical modes such as oval/triangle/square modes. Typically, identifying accurate material properties is a manual, time-consuming process, involving lots of trial and error. This study presents an automated workflow to calibrate the material properties for the stator with Ansys Mechanical and optiSLang. The developed workflow can track natural frequencies and corresponding mode shapes of critical modes, and adjust material constants automatically to find best material parameters for the given frequencies. It can rotate the mode shapes and find the orientation that gives best match to the measurements based on modal assurance criteria (MAC). This workflow has shown a good correlation between simulation and test in terms of natural frequencies and corresponding mode shapes for the stator of a switched reluctance motor (SRM). Such an automated workflow enables the fast, efficient material calibration process, therefore accurate electric powertrain NVH simulations.
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Ahriche, Aimad. "An Approach of Position and Torque Estimation for Induction Motor based Sensor-less Drive". International Journal of Circuits, Systems and Signal Processing 17 (6.03.2023): 44–49. http://dx.doi.org/10.46300/9106.2023.17.5.
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This paper presents a new approach with stability analysis, simulation and experimental investigation of a sliding mode based estimator for rotor-position and torque-load calculation in high performance speed-sensor-less AC motor drive. The proposed algorithm is built based on the induction motor (IM) fluxes equations for two rotationg referential frames. The First equation calculates the stator flux vector while the second gives the rotor flux vector. Moreover, the stator flux equation is linked to a stator-flux rotating referential frame and the rotor flux equation is linked to a rotor-flux rotating referential frame. Among merits of the proposed technique is no necessity to rotor-speed measurement and adaptation. Thus, it is well suitable to the fully speed-sensorless scheme. The whole observer stability is verified by using of Lyapunov’s principle. Simulations are done by using Matlab-Simulink and experimental implementation is performed in order to prove the feasibility of proposed algorithm. The illustrated results are shown by using a DS1104 controller board.
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Jannati, Mohammad, Tole Sutikno, Nik Rumzi Nik Idris i Mohd Junaidi Abdul Aziz. "Modeling of Balanced and Unbalanced Three-Phase Induction Motor under Balanced and Unbalanced Supply Based on Winding Function Method". International Journal of Electrical and Computer Engineering (IJECE) 5, nr 4 (1.08.2015): 644. http://dx.doi.org/10.11591/ijece.v5i4.pp644-655.
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<p>An accurate model of balanced and unbalanced three-phase Induction Motor (IM) under balanced and unbalanced supply conditions based on Winding Function Method (WFM) is presented in this work. In this paper, the unbalanced condition in three-phase IM is limited to stator winding open-phase fault. The analysis of presented models is shown in details which allow predicting the performance of 3-phase IM under different conditions. Computer simulations were obtained using the MATLAB software for a three-phase squirrel cage IM. MATLAB simulation results show that the oscillation of the speed and electromagnetic torque has increased considerably due to the open-phase fault in stator windings.</p>
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Brandão, André, Aline Souza de Paula, Marcelo Amorim Savi i Fabrice Thouverez. "Nonlinear Dynamics and Chaos of a Nonsmooth Rotor-Stator System". Mathematical Problems in Engineering 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/8478951.
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Rotor systems have wide applications in industries, including aero engines, turbo generators, and gas turbines. Critical behaviors promoted by the system unbalance and the contact between rotor and stator lead to important nonlinearities on system dynamics. This paper investigates the complex behavior presented by a rotor-stator system’s dynamics due to intermittent contact. A four-degree-of-freedom Jeffcott nonsmooth rotor/stator system is used to describe the rotor behavior, while a viscoelastic suspended rigid cylinder represents the stator. Numerical simulations are carried out showing rich dynamics that include periodic, quasiperiodic, and chaotic responses. Special attention is dedicated to chaotic behavior and the calculation of Lyapunov exponents is employed as a diagnostic tool.
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Sun, Peng, Wenguang Fu, Hong Wang i Jingjun Zhong. "Numerical research on inlet total pressure distortion in a transonic compressor with non-axisymmetric stator". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, nr 2 (14.11.2017): 667–78. http://dx.doi.org/10.1177/0954410017740385.
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The adverse impacts of non-uniform inlet flow have been the focus for several decades with the increase of the operating range of engines. A deep understanding of the flow mechanism of distortion passing through a compressor is needed urgently and the improvement of the compressor performance becomes more and more important. In this paper, a non-axisymmetric stator is presented with significant non-axisymmetric characteristics in a transonic compressor to investigate compressor performance and flow field effects. A time-dependent three-dimensional Reynolds-averaged Navier-Stokes equation composed in ‘Fluent Software Pack’ is validated and used to perform the simulations. The flow fields with distorted inlet are obtained and the effects of original stator and non-axisymmetric stator in a transonic compressor are compared. The results are discussed in terms of the effects of non-axisymmetric stator on compressor performance, blockage of flow passage, rotor and stator. The results show that the non-axisymmetric stator influences not only the stator flow field but also the rotor flow field, so the efficiency and total pressure ratio are improved correspondingly.
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Ding, Wei, Yulong Jin, Xijin Wu, Yufeng Yang i Yongjiang Jiang. "High-Resistance Connection Diagnosis of Doubly Fed Induction Generators". Energies 16, nr 22 (9.11.2023): 7516. http://dx.doi.org/10.3390/en16227516.
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The high resistance connection fault of the stator is a common fault in doubly fed induction generators, which causes a three-phase imbalance in the stator circuit. Since the stator winding is directly connected to the power grid, interference from the asymmetric power grid must be eliminated in order to achieve the accurate diagnosis of stator resistance imbalance faults. Therefore, a new diagnosis method based on filter shunt capacitor banks is proposed in this paper. By introducing shunt capacitor banks, an artificial neutral point is constructed to replace the neutral point of the power grid. Then, the neutral point voltage of the stator winding relative to the artificial neutral point is selected as a fault characteristic signal. In this paper, the change in three-phase stator currents after a high-resistance connection fault is analyzed in detail, and by comparing the fault characteristic signal with three-phase stator currents, the fault phase location and fault severity of high-resistance connection can be accurately obtained. Finally, simulations are carried out via the field-circuit coupling method to validate the effectiveness of the proposed method.
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Chen, Chien-Hsu, Hsiu-Ming Wu i Yue-Feng Lin. "Stator flux oriented multiple sliding-mode speed control design of induction motor drives". Advances in Mechanical Engineering 13, nr 5 (maj 2021): 168781402110217. http://dx.doi.org/10.1177/16878140211021734.
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Due to superior robustness characteristic of sliding-mode control techniques, this study proposes a multiple sliding-mode control (MSMC) strategy based on the stator flux oriented vector scheme for speed control of three-phase AC induction motor (IM) drives in the presence of an external disturbance and uncertainties. At first, the dynamic model of a three-phase IM drive is transformed into two-axe orthogonal model (i.e. d and q axes) in the synchronously rotating frame so that vector control can be applied. Then, based on the stator flux oriented scheme (i.e. zero stator flux at q-axis and constant at d-axis), the proposed MSMC causes mechanical angular speed and stator current at q-axis reach toward predefined sliding surfaces. Moreover, stator flux and current at d-axis are respectively indirect and direct controlled such that tracking errors approach toward designed sliding surfaces. The closed-loop stability of the proposed MSMC is proved to possess uniformly ultimately bounded (UUB) performance by Lyapunov stability criteria. Furthermore, the simulation results reveal that the proposed MSMC strategy has a high level of robustness despite addition of an external load and random uncertainties on system parameters. In the meantime, the simulations for comparing the baseline controller (i.e. conventional PI control) are also conducted to verify the superiority of the proposed control scheme.
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Laín-Beatove, Santiago, Manuel J. García.Ruiz, Brian Quintero-Arboleda i Santiago Orrego-Bustamante. "CFD Numerical simulations of Francis turbines". Revista Facultad de Ingeniería Universidad de Antioquia, nr 51 (20.03.2013): 31–40. http://dx.doi.org/10.17533/udea.redin.14917.
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In this paper the description of the internal flow in a Francis turbine is addressed from a numerical point of view. The simulation methodology depends on the objectives. On the one hand, steady simulations are able to provide the hill chart of the turbine and energetic losses in its components. On the other hand, unsteady simulations are required to investigate the fluctuating pressure dynamics and the rotor-stator interaction. Both strategies are applied in this paper to a working Francis turbine in Colombia. The employed CFD package is ANSYS-CFX v. 11. The obtained results are in good agreement with the in site experiments, especially for the characteristic curve.
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Benbouzid, Mohamed, Abdelkrim Benchaib, Gang Yao, Brice Beltran i Olivier Chocron. "A Metric Observer for Induction Motors Control". Journal of Control Science and Engineering 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/3631254.
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This paper deals with metric observer application for induction motors. Firstly, assuming that stator currents and speed are measured, a metric observer is designed to estimate the rotor fluxes. Secondly, assuming that only stator currents are measured, another metric observer is derived to estimate rotor fluxes and speed. The proposed observer validity is checked throughout simulations on a 4 kW induction motor drive.
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Jun, Bum-Su, Joon Park, Jun-Hyuk Choi, Ki-Doek Lee i Chung-Yuen Won. "Temperature Estimation of Stator Winding in Permanent Magnet Synchronous Motors Using d-Axis Current Injection". Energies 11, nr 8 (6.08.2018): 2033. http://dx.doi.org/10.3390/en11082033.
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This paper presents a stator winding temperature detection method for permanent magnet synchronous motors (PMSMs) using a motor parameter estimation method. PMSM performance is highly dependent on the motor parameters. However, the motor parameters vary with temperature. It is difficult to measure motor parameters using a voltage equation without additional sensors. Herein, a stator winding temperature estimation method based on a d-axis current injection method is proposed. The proposed estimation method can be used to obtain stator temperatures and to achieve reliable operation. The validity of the proposed method is verified through simulations and experimental results.
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Gaetani, Paolo, i Giacomo Persico. "Influence of the Rotor-Driven Perturbation on the Stator-Exit Flow within a High-Pressure Gas Turbine Stage". International Journal of Turbomachinery, Propulsion and Power 6, nr 3 (13.07.2021): 28. http://dx.doi.org/10.3390/ijtpp6030028.
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In stator–rotor interaction studies on axial turbines, the attention is commonly focused on the unsteady rotor aerodynamics resulting from the periodic perturbations induced by the stator flow structures. Conversely, less interest has been historically attracted regarding the influence of the rotor on the flow released by the stator, correlated to propagation of the blade potential field upstream of the rotor leading edge. In this paper, experiments in the research high-pressure turbine of the Laboratory of Fluid-Machines of the Politecnico di Milano, performed by applying a fast-response aerodynamic pressure probe, alongside fully-3D time-accurate CFD simulations of the flow, are combined with the aim of discussing the rotor-to-stator interaction. While rotating, the rotor induces periodic perturbations on the pressure and velocity field in the stator–rotor gap, altering the evolution of the total quantities and the flow rate discharged by each stator channel and eventually triggering energy-separation effects which result in total pressure and total temperature oscillations in the stator-exit flow. Such oscillations were found to rise up to almost ±10% of the stage total temperature drop.
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Guo, Chen. "A Spherical Planning Based Electrifying Strategy of Permanent Magnet Spherical Motor". Applied Mechanics and Materials 741 (marzec 2015): 629–45. http://dx.doi.org/10.4028/www.scientific.net/amm.741.629.
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Permanent Magnet SpherIcal Motor (PMSM) can be applIed on offshore O&M vessels for offshore wInd farms. An electrIfyIng strategy of PMSM Is proposed accordIng to the structure of PMSM wIth 3 layers of stator coIls. A statIc torque model of PMSM Is buIlt In thIs paper. In order to classIfy the statuses of rotor posItIon, spherIcal plannIng on stator spherIcal surface Is made and 4 classes of 72 sub-regIons are dIVIded accordIng to the dIstrIbutIon of stator coIls. Then stator coIls In each sub-regIon are marked wIth numbers and electrIfyIng rules of stator coIls In dIfferent statuses are desIgned. Of all the 54 stator coIls, 18 are sImultaneously electrIfIed under each status, wIth electrIfIed coIls unIformly dIstrIbuted. The concept OpposIte Corner CoIls of SpherIcal Surface (OCCSS) Is proposed. AccordIng to the control torque of PMSM, statIc torque model and the characterIstIcs of OCCSS, the currents flowIng though the electrIfIed 18 stator coIls are calculated. NumerIcal sImulatIons of contInuous path motIon and poInt-to-poInt motIon of rotor verIfIed the ratIonalIty of the proposed electrIfyIng strategy. A hypothetIcal ImplementatIon scheme of the system on whIch the electrIfyIng strategy can be actualIzed Is proposed.
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Tannous, Mikhael, Patrice Cartraud, Mohamed Torkhani i David Dureisseix. "Assessment of 3D modeling for rotor–stator contact simulations". Journal of Sound and Vibration 353 (wrzesień 2015): 327–43. http://dx.doi.org/10.1016/j.jsv.2015.05.025.
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Montiel, Miguel, i Roque Corral. "Time-Inclined Method for High-Fidelity Rotor/Stator Simulations". Aerospace 10, nr 5 (18.05.2023): 475. http://dx.doi.org/10.3390/aerospace10050475.
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The application of the time-inclined method in a fourth-order unstructured flux-reconstruction code for turbomachinery is demonstrated. Inviscid and viscous unsteady results due to the interaction of an incoming gust of total pressure with a linear cascade of flat plates and a linear cascade of T106A low-pressure turbine airfoils are reported. The agreement between the time-inclined method and the equivalent full-annulus multipassage solution is very high for both cases. Viscous solutions at Reynolds numbers of 104 and 105 were conducted. A high degree of matching was obtained between the time-inclined and the whole annulus approaches. The limitations of the method are explored and discussed. While the evolution of the unsteady boundary layers created by the interaction with the incoming wakes was very well captured, the mixing associated with the trailing edge vortex shedding was less accurate. The critical parameter controlling the method’s accuracy is the local Strouhal number. It was demonstrated that the benefit of retaining the exact blade count in the simulations overcomes the slight differences in the mixing due to the limitation of the time-inclined method to model viscous effects accurately in all situations.
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Taha Hussein, Hussein, Mohamed Ammar i Mohamed Moustafa Hassan. "Induction Motors Stator Fault Analysis based on Artificial Intelligence". Indonesian Journal of Electrical Engineering and Computer Science 2, nr 1 (1.04.2016): 69. http://dx.doi.org/10.11591/ijeecs.v2.i1.pp69-78.
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This article presents a method for fault detection and diagnosis of stator inter-turn short circuit in three phase induction machines. The technique is based on the stator current and modelling in the dq frame using an Adaptive Neuro-Fuzzy artificial intelligence approach. The developed fault analysis method is illustrated using MATLAB simulations. The obtained results are promising based on the new fault detection approach.
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Setty Allampalli, Ravikumar, PurnaPrajna R. Mangsuli i Kishore Chatterjee. "Novel Compensation Method to Reduce Rotor Position Estimation Error and Torque Reduction in Signal Injection Based PMSM Drives". International Journal of Power Electronics and Drive Systems (IJPEDS) 8, nr 2 (1.06.2017): 548. http://dx.doi.org/10.11591/ijpeds.v8.i2.pp548-557.
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High frequency signal injection techniques are widely used to extract rotor position information from low speed to stand still. Accuracy of estimated rotor position is decreased when stator winding resistance is neglected. Position estimation error also results in output Torque reduction. Parasitic resistance of stator winding causes significant position estimation error <br /> and Torque reduction, if not compensated. Signal injection techniques developed in the literature does not provide detailed analysis and compensation methods to improve rotor position estimation of PMS Motors, where stator winding resistance cannot be neglected. This work analyzes the stator winding resistance effect on position estimation accuracy and proposes novel compensation technique to reduce the position estimation error and torque reduction introduced by stator winding resistance. Prototype hardware of a self-sensing PMSM drive is developed. The effectiveness of the proposed method is verified with the MATLAB/Simulink simulations and experimental results on a prototype self-sensing PMSM drive.
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Krishtop, Ihor, Victor German, Alexander Gusak, Svitlana Lugova i Alexey Kochevsky. "Numerical Approach for Simulation of Fluid Flow in Torque Flow Pumps". Applied Mechanics and Materials 630 (wrzesień 2014): 43–51. http://dx.doi.org/10.4028/www.scientific.net/amm.630.43.
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Torque flow pumps are widely used for pumping of fluids with high content of solid and fibrous inclusions and gas bubbles, in particular, for pumping of sewage and wastes. Fluid flow in these pumps is featured with strong vortex patterns, making it difficult to predict reliably their performance curves numerically. The paper is devoted to selection of a numerical approach for simulation of fluid flow in a torque flow pump of “Turo” type and its influence on simulation results. In particular, influence of geometrical configuration of the rotor-stator interface as well as numerical grid fineness is demonstrated. For one geometric configuration, the fluid flow is simulated with different turbulent models, with a steady state as well as transient approach. The simulations were performed using the software product ANSYS CFX. The simulation results are compared with the experimental measurements in the torque flow pump of “Turo” type. The experimental research included probing of fluid flow in three cross-sections of the stator domain, visualizing of streamlines along the rotating and stationary walls, as well as obtaining of performance curves. A good agreement between the numerical and experimental results is obtained as the rotor-stator interface is located at some distance off the rotating parts. Influence of choice of the turbulence model on the simulation results is demonstrated. Conclusions and recommendations are made concerning the choice of initial and boundary conditions, geometrical configuration of the rotor-stator interface, and parameters of turbulence models that affect both the flow pattern in the pump and its performance curves as well as the numerical solution time and required computational resources.
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Kruchinina, Irina Yu, Yuvenaliy Khozikov, Alexandr Liubimtsev i Valentina Paltceva. "Harmonic losses in high-speed PM synchronous machines". COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 36, nr 3 (2.05.2017): 683–91. http://dx.doi.org/10.1108/compel-09-2016-0401.
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Purpose The purpose of this paper is the development of a new numerical method for the calculation of the air-gap magnetic flux harmonics in synchronous machines with permanent magnet (PM) excitation. The harmonic analysis results are used as input data for the eddy-current loss calculation and for the rotor heating evaluation. Design/methodology/approach The method is based on the finite element analysis (FEA). The model takes into account toothed stator design, rotor asymmetrical magnetic reluctance and saturation. At first, a series of static DC magnetic (magnetostatic) simulations is run. Each problem corresponds to specific rotor position and the momentary stator winding currents. The Fourier analysis performed for each problem yields the harmonic spectrum variation in time. Then, a series of AC magnetic (time-harmonic) simulations is run. Each problem corresponds to a specific harmonic. The result is the eddy-current losses distribution. After total loss is calculated, the heat transfer analysis is conducted. Findings The analysis reveals that 90 per cent of losses are located in the sleeve that holds PMs together. Rotor eccentricity brings even harmonics of low magnitude that have little impact on heating. Originality/value In general, the study requires transient electromagnetic analysis with motion. The purposed method allows to simplify the problem. The method is based on static and quasi-static (time-harmonic) problems simulation. It is fast and highly automated. The method allows simultaneous taking into account of tooth-order harmonics, stator winding harmonics and eccentricity for heating calculation.
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Hösgen, Thomas, Matthias Meinke i Wolfgang Schröder. "Large-Eddy Simulations of Rim Seal Flow in a One-Stage Axial Turbine". Journal of the Global Power and Propulsion Society 4 (23.12.2020): 309–21. http://dx.doi.org/10.33737/jgpps/129704.
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The flow field in a one-stage axial flow turbine with 30 stator and 62 rotor blades including the wheel space is investigated by large-eddy simulation (LES). The Navier-Stokes equations are solved using a massively parallel finite-volume solver based on a Cartesian mesh with immersed boundaries. The strict conservation of mass, momentum, and energy is ensured by an efficient cut-cell/level-set ansatz, where a separate level-set solver describes the motion of the rotor. Both solvers use individual subsets of a shared Cartesian mesh, which they can adapt independently. The focus of the analysis is on the flow field inside the rotor stator cavity between the stator and rotor disks. Two cooling gas mass flow rates are investigated for the same rim seal geometry. First, the time averaged flow field for both simulations is compared, followed by a detailed investigation of the unsteady flow field. The results for the cooling effectiveness are compared to experimental data. Both cases show good agreement with experimental data. It is shown that for the lower cooling gas mass flux several of the wheel space’s acoustic waves are excited. This is not observed for the higher cooling gas mass flux. The excited waves lead to stable, i.e., bounded, fluctuations inside the wheel space and result in a significantly higher hot gas ingestion.
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Jiang, Jun. "The Analytical Solution and The Existence Condition of Dry Friction Backward Whirl in Rotor-to-Stator Contact Systems". Journal of Vibration and Acoustics 129, nr 2 (20.04.2006): 260–64. http://dx.doi.org/10.1115/1.2345677.
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Dry friction backward whirl is a self-excited vibration state in rotor-to-stator contact systems, by which the rotor is in continuous contact with the stator, slipping continuously on the contact surface and whirling backward at a supersynchronous frequency. To correctly cope the response of dry friction backward whirl, the effect of dry friction must be taken into account in rotor/stator models. From the knowledge on the characteristics of dry friction backward whirl, the whirl frequency, the existence condition and the solution of this response are derived analytically in this paper. The analytical results are verified by simulations and shown in good correspondence to the experimental observations.
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Nguyen, Dung Quang, Quang Thanh Nguyen, Trung Van Nguyen, Tai Huu Le, Hau Huu Vo i Pavel Brandstetter. "Simplified Control Structure of Fuzzy Logic and Kalman Filter for Induction Motor Drive". Journal of Advanced Engineering and Computation 5, nr 3 (30.09.2021): 189. http://dx.doi.org/10.55579/jaec.202153.334.
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The paper deals with the utilization of Kalman filter and fuzzy logic control in induction motor drive with direct torque control (DTC). In order to lower ripple of stator current vector in DTC drive, pulse width modulation technique with high switching frequency is applied. However, the performance of the DTC also depends on the accuracy of both stator resistance and stator current vector. In the paper, the stator resistance and stator current components are assumed to be distorted by Gaussian noises. In order to reduce the effect of noises especially at low speed and very low speed regions, a simple Kalman filter is applied for filtering current components, and fuzzy logic theory is used to increase the flexibility of proportional-integral (PI) compensator in the speed controller of the drive structure. Simulations are implemented in conditions of high-level noises of stator current and stator resistance, and a wide range of load torque. An ITAE-based criterion is utilized to evaluate the performance of drive structures. Results confirmed the expected dynamic properties of the proposed drive structure. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.
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Childs, Dara W., i Avijit Bhattacharya. "Prediction of Dry-Friction Whirl and Whip Between a Rotor and a Stator". Journal of Vibration and Acoustics 129, nr 3 (30.01.2007): 355–62. http://dx.doi.org/10.1115/1.2731412.
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This paper addresses recent test results for dry-friction whip and whirl. Authors of these publications suggest that predictions from Black’s 1968 paper (J. Mech. Eng. Sci., 10(1), pp. 1–12) are deficient in predicting their observed transition speeds from whirl to whip and the associated precession frequencies of whirl and whip motion. Predictions from Black’s simple Jeffcott-rotor/point-mass stator are cited. This model is extended here to a multimode rotor and stator model with an arbitrary axial location for rotor-stator rubbing. Predictions obtained from this new model are quite close to experimental observations in terms of the transition from whip to whirl and observed precession frequencies. Paradoxically, nonlinear numerical simulations using Black’s model fail to produce the whirl and whip solutions. The Coulomb friction force in Black’s model has a fixed direction, and Bartha showed in 2000 (“Dry Friction Backward Whirl of Rotors,” Dissertation, THE No. 13817, ETH Zurich) that by making the friction-force direction depend on the relative sliding velocity, nonlinear simulations would produce the predicted whirl solutions. He also showed that Black’s proposed whip solution at the upper precession-frequency transition from whirl to whip was unstable. The multimode extension of Black’s model predicts a complicated range of whirl and whip possibilities; however, nonlinear time-transient simulations (including the sgn function definition for the Coulomb force) only produce the initial whirl precession range, initial whirl-whip transition, and initial whip frequency. Simulation results for these values agree well with predictions. However, none of the predicted higher-frequency whirl results are obtained. Also, the initial whip frequency persists to quite high running speeds and does not (as predicted) transition to higher frequencies. Hence, despite its deficiencies, correct and very useful predictions are obtained from a reasonable extension of Black’s model.
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Chaluvadi, V. S. P., A. I. Kalfas i H. P. Hodson. "Vortex Transport and Blade Interactions in High Pressure Turbines". Journal of Turbomachinery 126, nr 3 (1.07.2004): 395–405. http://dx.doi.org/10.1115/1.1773849.
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This paper presents a study of the three-dimensional flow field within the blade rows of a high-pressure axial flow steam turbine stage. Half-delta wings were fixed to a rotating hub to simulate an upstream rotor passage vortex. The flow field is investigated in a low-speed research turbine using pneumatic and hot-wire probes downstream of the blade row. The paper examines the impact of the delta wing vortex transport on the performance of the downstream blade row. Steady and unsteady numerical simulations were performed using structured three-dimensional Navier-Stokes solver to further understand the flow field. The loss measurements at the exit of the stator blade showed an increase in stagnation pressure loss due to the delta wing vortex transport. The increase in loss was 21% of the datum stator loss, demonstrating the importance of this vortex interaction. The transport of the stator viscous flow through the rotor blade row is also described. The rotor exit flow was affected by the interaction between the enhanced stator passage vortex and the rotor blade row. Flow underturning near the hub and overturning towards the midspan was observed, contrary to the classical model of overturning near the hub and underturning towards the midspan. The unsteady numerical simulation results were further analyzed to identify the entropy producing regions in the unsteady flow field.
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Papagiannis, Ilias, Asad Raheem, Altug Basol, Anestis Kalfas, Reza Abhari, Hisataka Fukushima i Shigeki Senoo. "Unsteady flow mechanisms in the last stage of a transonic low pressure steam turbine—multistage effects and tip leakage flows". Journal of the Global Power and Propulsion Society 1 (20.07.2017): F4IW8S. http://dx.doi.org/10.22261/f4iw8s.
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Abstract In this paper, an unsteady investigation of the last two stages of a low-pressure steam turbine with supersonic airfoils near the tip of the last stage’s rotor blade is presented. Goal is the investigation of multistage effects and tip leakage flow in the last stage of the turbine and to provide insight on the stator-rotor flow interaction in the presence of a bow-shock wave. This study is unique in a sense of combining experimental data for code validation and comparison with a numerical simulation of the last two stages of a real steam turbine, including tip-cavity paths and seals, steam modelling and experimental data used as inlet and outlet boundary conditions. Analysis of results shows high unsteadiness close to the tip of the last stage, due to the presence of a bow-shock wave upstream of the rotor blade leading edge and its interaction with the upstream stator blades, but no boundary layer separation on stator is detected at any instant in time. The intensity of the shock wave is weakest, when the axial distance of the rotor leading edge from the upstream stator trailing edge is largest, since it has more space available to weaken. However, a phase shift between the maximum values of static pressure along the suction side of the stator blade is identified, due to the shock wave moving with the rotor blades. Additionally, the bow-shock wave interacts with the blade shroud and the tip leakage flow. Despite the interaction with the incoming flow, the total tip leakage mass flow ingested in the tip-cavity shows a steady behaviour with extremely low fluctuations in time. Finally, traces of upstream stage’s leakage flow have been identified in the last stage, contributing to entropy generation in inlet and outlet of last stage’s stator blade, highlighting the importance of performing multistage simulations.
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Huang, Yi, i Clemens Gühmann. "Wireless Sensor Network for Temperatures Estimation in an Asynchronous Machine Using a Kalman Filter". ACTA IMEKO 7, nr 1 (1.04.2018): 5. http://dx.doi.org/10.21014/acta_imeko.v7i1.509.
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<p class="Abstract">A 4<sup>th</sup>-order Kalman filter (KF) algorithm is developed based on the thermal model of an asynchronous machine. The thermal parameters are identified and KF is implemented in a wireless sensor network (WSN) to estimate the temperatures of the stator windings, the rotor cage, and the stator core of an asynchronous machine. The rotor speed, coolant air temperature, and the effective current and voltage are acquired by a WTIM (wireless transducer interface module) separately and transmitted to a NCAP (network capable application processor) where the KF algorithm is implemented. Losses of the stator windings and the rotor cage are copper losses, and the stator core losses are iron losses. The losses of the stator windings, the rotor cage and the stator core are calculated from the measurements and are processed with the coolant air temperature by KF. As the resistance varies from temperature, the estimated temperature of the stator windings is used for compensating the rising of resistance. Simulations and experiments on the test bench were performed before the KF algorithm is implemented on a wireless sensor node. The real-time temperature estimator on WSN is independent of control algorithm and can work under any load condition with very high accuracy.</p>
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Lugaresi, Marco, Diego Villa i Stefano Gaggero. "Design by Optimization on the Nozzle and the Stator Blades of a Rim-Driven Pumpjet". Journal of Marine Science and Engineering 12, nr 11 (19.11.2024): 2090. http://dx.doi.org/10.3390/jmse12112090.
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The design of the stator and nozzle of a rim-driven pumpjet thruster (RDPJ) is addressed through a simulation-based design optimization approach built on a parametric description of the main geometrical characteristics of the system, a RANS solver with actuator disk model, and a genetic algorithm. As the propeller blades’ geometry is fixed, the rotor/stator (RDPJ-R/S) configuration is considered for the optimal design from a multi-objective optimization process aimed at minimizing the resistance keeping the cavitation inception index at the lowest possible value. Steady-state (moving reference frame plus mixing plane interface) and unsteady simulations (sliding meshes) with fully resolved rotor geometry were finally carried out on six selected optimal geometries to validate the optimization process and the performance improvements provided by the RDPJ configuration when compared with the original rim-driven thruster (RDT).
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Goldman, P., i A. Muszynska. "Chaotic Behavior of Rotor/Stator Systems With Rubs". Journal of Engineering for Gas Turbines and Power 116, nr 3 (1.07.1994): 692–701. http://dx.doi.org/10.1115/1.2906875.
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This paper outlines the dynamic behavior of externally excited rotor/stator systems with occasional, partial rubbing conditions. The observed phenomena have one major source of a strong nonlinearity: transition from no contact to contact state between mechanical elements, one of which is rotating, resulting in variable stiffness and damping, impacting, and intermittent involvement of friction. A new model for such a transition (impact) is developed. In case of the contact between rotating and stationary elements, it correlates the local radial and tangential (“super ball”) effects with global behavior of the system. The results of numerical simulations of a simple rotor/stator system based on that model are presented in the form of bifurcation diagrams, rotor lateral vibration time-base waves, and orbits. The vibrational behavior of the system considered is characterized by orderly harmonic and subharmonic responses, as well as by chaotic vibrations. A new result is obtained in case of heavy rub of an anisotropically supported rotor. The system exhibits an additional subharmonic regime of vibration due to the stiffness asymmetry. The correspondence between numerical simulation of that effect and previously obtained experimental data supports the adequacy of the new model of impact.
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Jacques, R., P. Le Quéré i O. Daube. "Axisymmetric numerical simulations of turbulent flow in rotor stator enclosures". International Journal of Heat and Fluid Flow 23, nr 4 (sierpień 2002): 381–97. http://dx.doi.org/10.1016/s0142-727x(02)00137-6.
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Viazzo, Stéphane, Sébastien Poncet, Eric Serre, Anthony Randriamampianina i Patrick Bontoux. "High-order Large Eddy Simulations of Confined Rotor-Stator Flows". Flow, Turbulence and Combustion 88, nr 1-2 (6.04.2011): 63–75. http://dx.doi.org/10.1007/s10494-011-9345-0.
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Perin, Deniz, Aslan Deniz Karaoglan i Kemal Yilmaz. "Rotor design optimization of a 4000 rpm permanent magnet synchronous generator using moth flame optimization algorithm". An International Journal of Optimization and Control: Theories & Applications (IJOCTA) 14, nr 2 (26.03.2024): 123–33. http://dx.doi.org/10.11121/ijocta.1407.
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The goal of this paper is to optimize the rotor design parameters of 4000 rpm permanent magnet synchronous generator. The factors namely embrace, offset, outer diameter, and magnet thickness are selected as the design parameters those will be optimized in order to hold the magnetic flux density (MFD) distribution and the flux density on stator teeth and stator yoke within a desirable range while maximizing efficiency. The numerical simulations are carried out in the Maxwell environment for this purpose. The mathematical relationships between the responses and the factors are then derived using regression modeling over the simulation data. Following the modeling phase, the moth flame optimization is applied to these regression models to optimize the rotor design parameters. The motivation is determining mathematical relation between the important design parameters of the high speed generator and the measured responses, when standard M530-50A lamination material is used and then to demonstrate the utility of MFO to the readers on this design problem. The optimum factor levels for embrace, offset, outer diameter, and magnet thickness are calculated as 0.68, 30, 161.56, and 8.92 respectively. Additionally, confirmations are done by using Maxwell and the efficiency is calculated as 94.85%, and magnetic distributions are calculated as 1.64, 0.26, and 0.93 Tesla for stator teeth flux density, stator yoke flux density, and MFD; respectively. The results show that the efficiency is maximized and the magnetic distributions are kept within an appropriate range.
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Chen, Junlei, Shuo Chen, Xiang Wu, Guojun Tan i Jianqi Hao. "A Super-Twisting Sliding-Mode Stator Flux Observer for Sensorless Direct Torque and Flux Control of IPMSM". Energies 12, nr 13 (3.07.2019): 2564. http://dx.doi.org/10.3390/en12132564.
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The scheme based on direct torque and flux control (DTFC) as well as active flux is a good choice for the interior permanent magnet synchronous motor (IPMSM) sensorless control. The precision of the stator flux observation is essential for this scheme. However, the performance of traditional observers like pure integrator and the low-pass filter (LPF) is severely deteriorated by disturbances, especially dc offset. Recently, a sliding-mode stator flux observer (SMFO) was proposed to reduce the dc offset in the estimated stator flux. However, it cannot eliminate the dc offset totally and will cause the chattering problem. To solve these problems, a novel super-twisting sliding-mode stator flux observer (STSMFO) is proposed in this paper. Compared with SMFO, STSMFO can reduce the chattering and fully eliminate the dc offset without any amplitude and phase compensation. Then, the precision of the stator flux and rotor position can be greatly improved over a wide speed region. The detailed mathematical analysis has been given for comparing it with another three traditional observers. The numerical simulations and experimental testing with an IPMSM drive platform have been implemented to verify the capability of the proposed sensorless scheme.
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Gorrell, Steven E., Theodore H. Okiishi i William W. Copenhaver. "Stator-Rotor Interactions in a Transonic Compressor—Part 2: Description of a Loss-Producing Mechanism". Journal of Turbomachinery 125, nr 2 (1.04.2003): 336–45. http://dx.doi.org/10.1115/1.1540120.
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A previously unidentified loss producing mechanism resulting from the interaction of a transonic rotor blade row with an upstream stator blade row is described. This additional loss occurs only when the two blade rows are spaced closer together axially. Time-accurate simulations of the flow and high-response static pressure measurements acquired on the stator blade surface reveal important aspects of the fluid dynamics of the production of this additional loss. At close spacing the rotor bow shock is chopped by the stator trailing edge. The chopped bow shock becomes a pressure wave on the upper surface of the stator that is nearly normal to the flow and that propagates upstream. In the reference frame relative to this pressure wave, the flow is supersonic and thus a moving shock wave that produces an entropy rise and loss is experienced. The effect of this outcome of blade-row interaction is to lower the efficiency, pressure ratio, and mass flow rate observed as blade-row axial spacing is reduced from far to close. The magnitude of loss production is affected by the strength of the bow shock and how much it turns as it interacts with the trailing edge of the stator. At far spacing the rotor bow shock degenerates into a bow wave before it interacts with the stator trailing edge and no significant pressure wave forms on the stator upper surface. For this condition, no additional loss is produced.