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1
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.
2
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.
3
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.
4
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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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.
6
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.
7
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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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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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.
10
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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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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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.
13
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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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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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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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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Nguyen, Manh-Dung, Tae-Seong Kim, Kyung-Hun Shin, Gang-Hyeon Jang i Jang-Young Choi. "Fast Prediction of Characteristics in Wound Rotor Synchronous Condenser Using Subdomain Modeling". Mathematics 12, nr 22 (12.11.2024): 3526. http://dx.doi.org/10.3390/math12223526.
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Wound rotor synchronous condensers (WRSCs) are DC-excited rotor machines that utilize rotor winding instead of permanent magnets. Their voltage regulator controls the rotor field to generate or absorb reactive power, thereby regulating grid voltage or improving power factor. A key characteristic of a WRSC is the compounding curve, which shows the required rotor current under specific stator current and voltage conditions. This paper presents an approach for quickly calculating the electromagnetic parameters of a WRSC using a mathematical method. After determining magnetic flux density, induced voltage, and inductance through analytical methods, the Park and Clarke transformations are applied to derive the dq-frame quantities, enabling prediction of active and reactive powers and compounding curve characteristics. The 60 Hz model was evaluated through comparison with finite element method (FEM) simulations. Results of flux density, induced voltage, and the compounding curve under varying rotor and stator current conditions showed that the proposed method achieved comparable performance to FEM simulation while reducing computational time by half.
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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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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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Niu, Han, Jiang Chen i Hang Xiang. "A New Influence Mechanism of Clocking Effect in Subsonic Compressor". Applied Sciences 13, nr 18 (7.09.2023): 10094. http://dx.doi.org/10.3390/app131810094.
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This paper investigates the clocking effect in subsonic compressor element stages and the influence of design parameters on the flow mechanism. We focus on the relationship between the wake-induced separation loss and wake mixing loss and the unsteady mechanism in the wake flow process without considering the transition through several steady and unsteady numerical simulations aimed at a series of subsonic compressor element stages. The simulation results indicate that the performance difference at various indexing positions depends on the relationship between wake mixing loss and wake-induced separation loss for different compressor designs and operating conditions. Furthermore, the pressure transport caused by the negative jet of the Stator 0 wake in Rotor 1 creates a local acceleration region called SFAF, and a decrease in its absolute flow angle reduces the Stator 1 separation. Sufficient rim work of the rotor at highly loaded operating conditions is the basis for generating an effective SFAF. Furthermore, the fore-loading blade of Rotor 1 significantly reduces suction surface pressure drop, and a small angle between the stagger angles of Stator 0 and Rotor 1 increases the unsteady rotor load caused by the upstream wake to the total rotor load, both of which enhance SFAF.
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Hao, Z., X. Yang i Z. Feng. "Unsteady simulations of migration and deposition of fly-ash particles in the first-stage turbine of an aero-engine". Aeronautical Journal 125, nr 1291 (12.04.2021): 1566–86. http://dx.doi.org/10.1017/aer.2021.27.
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AbstractParticulate deposits in aero-engine turbines change the profile of blades, increase the blade surface roughness and block internal cooling channels and film cooling holes, which generally leads to the degradation of aerodynamic and cooling performance. To reveal particle deposition effects in the turbine, unsteady simulations were performed by investigating the migration patterns and deposition characteristics of the particle contaminant in a one-stage, high-pressure turbine of an aero-engine. Two typical operating conditions of the aero-engine, i.e. high-temperature take-off and economic cruise, were discussed, and the effects of particle size on the migration and deposition of fly-ash particles were demonstrated. A critical velocity model was applied to predict particle deposition. Comparisons between the stator and rotor were made by presenting the concentration and trajectory of the particles and the resulting deposition patterns on the aerofoil surfaces. Results show that the migration and deposition of the particles in the stator passage is dominated by the flow characteristics of fluid and the property of particles. In the subsequential rotor passage, in addition to these factors, particles are also affected by the stator–rotor interaction and the interference between rotors. With higher inlet temperature and larger diameter of the particle, the quantity of deposits increases and the deposition is distributed mainly on the Pressure Side (PS) and the Leading Edge (LE) of the aerofoil.
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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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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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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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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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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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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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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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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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Wang, Chunze, Rui Feng, Yao Chu, Qing Tan, Chaoyang Xing i Fei Tang. "Simulations of the Rotor-Stator-Cavity Flow in Liquid-Floating Rotor Micro Gyroscope". Micromachines 14, nr 4 (31.03.2023): 793. http://dx.doi.org/10.3390/mi14040793.
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When rotating at a high speed in a microscale flow field in confined spaces, rotors are subject to a complex flow due to the joint effect of the centrifugal force, hindering of the stationary cavity and the scale effect. In this paper, a rotor-stator-cavity (RSC) microscale flow field simulation model of liquid-floating rotor micro gyroscopes is built, which can be used to study the flow characteristics of fluids in confined spaces with different Reynolds numbers (Re) and gap-to-diameter ratios. The Reynolds stress model (RSM) is applied to solve the Reynolds averaged Navier–Stokes equation for the distribution laws of the mean flow, turbulence statistics and frictional resistance under different working conditions. The results show that as the Re increases, the rotational boundary layer gradually separates from the stationary boundary layer, and the local Re mainly affects the distribution of velocity at the stationary boundary, while the gap-to-diameter ratio mainly affects the distribution of velocity at the rotational boundary. The Reynolds stress is mainly distributed in boundary layers, and the Reynolds normal stress is slightly greater than the Reynolds shear stress. The turbulence is in the state of plane-strain limit. As the Re increases, the frictional resistance coefficient increases. When Re is within 104, the frictional resistance coefficient increases as the gap-to-diameter ratio decreases, while the frictional resistance coefficient drops to the minimum when the Re exceeds 105 and the gap-to-diameter ratio is 0.027. This study can enable a better understanding of the flow characteristics of microscale RSCs under different working conditions.
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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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Wei, Wen Xiang, i Xiao Ping Zhang. "Flux and Speed Estimation Based on the Extended State Observer for Speed Sensorless Control of Indirect Field Oriented Induction Motor Drives". Applied Mechanics and Materials 273 (styczeń 2013): 414–18. http://dx.doi.org/10.4028/www.scientific.net/amm.273.414.
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A flux observer based on the extended state observer (ESO) is proposed for rotor flux estimation and speed identification of indirect field oriented induction motor drives system. The uncertain component including rotor resistance and speed in the stator current equation is extended to a new state, the ESO is then constructed. By the current estimate error, the uncertain component convergences to its actual value and the accurate rotor flux, speed and the rotor time constant are obtained. The accuracy of the ESO independent the rotor resistance and load torque variations, simulations under high and low speed show that the proposed method achieves prefect robust, and the validity and practicability is verified by simulation results.
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Jurdana, Vedran, Neven Bulic i Wolfgang Gruber. "Topology Choice and Optimization of a Bearingless Flux-Switching Motor with a Combined Winding Set". Machines 6, nr 4 (6.11.2018): 57. http://dx.doi.org/10.3390/machines6040057.
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The purpose of this paper is to choose a new topology for bearingless flux-switching slice motors, regarding the number of stator and rotor poles, with a combined winding set. Additionally, the selected motor topology is optimized with finite element method (FEM) simulations to improve the performance. Bearingless slice drives feature a magnetically-suspended rotor disk passively stabilized by reluctance forces due to a permanent magnet (PM) bias flux in the air gap and actively controlled by the generation of radial bearing forces and motor torque. Usage of the combined winding set, where each phase generates both motor torque and suspension forces, opens the opportunity for a new topology. The topology choice and optimization are based on FEM simulations of several motor optimization criteria, as the passive axial, tilting and radial stiffness values and the active torque and bearing forces, which are simulated regarding the motor height and specific stator and rotor parameters. Saturation, cogging torque and cogging forces are also analyzed. The 3D FEM program ANSYS Maxwell 2015 was used. The results led to an optimized bearingless flux-switching motor topology with six new stator segments and seven rotor poles. By optimizing the geometry, a considerable improvement of performance was reached. This geometry optimization is a base for a future prototype model.
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Qin, Denghui, Qiaogao Huang, Guang Pan, Liming Chao, Yang Luo i Peng Han. "Effect of the odd and even number of blades on the hydrodynamic performance of a pre-swirl pumpjet propulsor". Physics of Fluids 34, nr 3 (marzec 2022): 035120. http://dx.doi.org/10.1063/5.0080661.
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A numerical study based on detached eddy simulations is conducted to investigate the effects of the odd and even number of rotor/stator blades, that is, nr/ ns, on the hydrodynamic performance of a pre-swirl pumpjet propulsor (PJP). In this paper, six PJPs, the PJP 6-4 ( ns– nr), 8-6, 10-8, 7-5, 9-7, and 11-9, are created. The hydrodynamic performance, the unsteady force of blades, and the wake structure of the PJPs are compared. The results show that the frequency of the fluctuating force of the whole rotor highly depends on the number or, more specifically, the parity of nr. When the parameter nr is the even number, it can be found that the total unsteady force of the rotor blades will be strengthened at the k-order stator-blades-passing frequency ([Formula: see text]). Moreover, it indicates that the superposition-enhancement coefficient (is defined as [Formula: see text]) at [Formula: see text] equals to nr, at least from the present tests. In terms of both the rotor and stator numbers are even, a phenomenon of the rotor–stator resonance occurs at [Formula: see text], where fn represents the hub rotational frequency. This work is expected to give some insight in the design of a PJP.
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Carta, Mario, Shahrokh Shahpar, Tiziano Ghisu i Fabio Licheri. "Multi-Fidelity Modelling of the Effect of Combustor Traverse on High-Pressure Turbine Temperatures". Aerospace 11, nr 9 (12.09.2024): 750. http://dx.doi.org/10.3390/aerospace11090750.
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As turbine entry temperatures of modern jet engines continue to increase, additional thermal stresses are introduced onto the high-pressure turbine rotors, which are already burdened by substantial levels of centrifugal and gas loads. Usually, for modern turbofan engines, the temperature distribution upstream of the high-pressure stator is characterized by a series of high-temperature regions, determined by the circumferential arrangement of the combustor burners. The position of these high-temperature regions, both radially and circumferentially in relation to the high-pressure stator arrangement, can have a strong impact on their subsequent migration through the high-pressure stage. Therefore, for a given amount of thermal power entering the turbine, a significant reduction in maximum rotor temperatures can be achieved by adjusting the inlet temperature distribution. This paper is aimed at mitigating the maximum surface temperatures on a high-pressure turbine rotor from a modern commercial turbofan engine by conducting a parametric analysis and optimization of the inlet temperature field. The parameters considered for this study are the circumferential position of the high-temperature spots, and the overall bias of the temperature distribution in the radial direction. High-fidelity unsteady (phase-lag) and conjugate heat transfer simulations are performed to evaluate the effects of inlet clocking and radial bias on rotor metal temperatures. The optimized inlet distribution achieved a 100 K reduction in peak high-pressure rotor temperatures and 7.5% lower peak temperatures on the high-pressure stator vanes. Furthermore, the optimized temperature distribution is also characterized by a significantly more uniform heat load allocation on the stator vanes, when compared to the baseline one.
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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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Valkov, T. V., i C. S. Tan. "Effect of Upstream Rotor Vortical Disturbances on the Time-Averaged Performance of Axial Compressor Stators: Part 2—Rotor Tip Vortex/Streamwise Vortex–Stator Blade Interactions". Journal of Turbomachinery 121, nr 3 (1.07.1999): 387–97. http://dx.doi.org/10.1115/1.2841331.
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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 stator 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 flowfield 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 2, the focus will be on the interaction of stator with the moving upstream rotor tip and streamwise vortices, the controlling parametric trends, and implications on design.
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Zhang, Guochen, Tianyi Gao, Zhihui Xu, Pengcheng Liu i Chengfeng Zhang. "Influences of slotted blade on performance and flow structure of a transonic axial compressor". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 235, nr 6 (17.02.2021): 1344–54. http://dx.doi.org/10.1177/0957650921994382.
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Main reason of compressor instability is boundary layer separation on the surface of blades. As one of flow control methods of the compressor, slotted blade has attracted many researchers’ attention because of its simple geometric structure and remarkable flow control effect. In order to evaluate its availability in the compressor, a type of convergent slot is designed to implement in a single-stage transonic axial compressor. Three configurations, i.e. rotor slot, stator slot and rotor-stator combined slot, are introduced to study the aerodynamic performance of compressor by numerical simulations. Furthermore, flow structures have been analyzed to explain the corresponding mechanism. The results show that overall stability margin of the compressor has been improved by flow control with slotted blade. Behavior of the rotor slot is better than that of the stator slot, but due to mass flow leakage in the slot, peak efficiency and chocking mass flow rate of the compressor are decreased by 1.18% and 3.8% respectively. The low momentum flow on pressure surface is sucked into the jet slot of stator blade, which improves the overall stability margin of 0.63%. The combined scheme with slotted rotor and slotted stator has obtained the best aerodynamic behavior with the increase of the overall stability margin of 2.83%. During the future research, main goal will be improvement of the compressor performance and extension of the mass flow rate range.
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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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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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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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Mankbadi, Reda R. "A Study of Unsteady Rotor–Stator Interactions". Journal of Turbomachinery 111, nr 4 (1.10.1989): 394–400. http://dx.doi.org/10.1115/1.3262286.
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This work is concerned with simulations of rotor-generated unsteady response of the turbulent flow in a stator. The rotor’s effect is represented by moving cylinders of equivalent drag coefficient that produce passing wakes at the entrance of the stator. The unsteady incompressible Navier–Stokes equations are solved on a staggered grid and eddy viscosities are obtained using a k–ε model. The rotor-generated wakes were found to produce a pressure field at the stator’s entrance that increases in the direction of the wake traverse. At a streamwise distance equal to the distance between the stator blades, the pressure becomes uniform across the channel and the oscillations in the pressure field decay. Because of the initial asymmetry of the pressure field, the time-averaged mean velocity is no longer symmetric. This asymmetry of the mean flow continues along the passage even after the pressure has regained its symmetry. As a result of the passing of the rotor-generated wakes, large periodic oscillations are introduced into the mean velocity and turbulence energy. The time-averaged turbulence energy and the wall shear stress increases in the direction of the rotor traverse.
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Wang, Zhuo, Lin Du i Xiaofeng Sun. "Enhancement of Rotor Loading and Suppression of Stator Separation through Reduction of the Blade–Row Gap". International Journal of Turbomachinery, Propulsion and Power 8, nr 1 (1.03.2023): 6. http://dx.doi.org/10.3390/ijtpp8010006.
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An immersed boundary (IB) method is applied to study the effect of the blade–row gap in a low-speed single-stage compressor. The advantage of using an IB method is that the rotor/stator interface can be eliminated and, thus, the blade–row interaction can be considered at an extremely small gap. The IB method was modified to internal-flow problems, and the adaptive mesh refinement (AMR) technique, together with a wall model, used to facilitate the simulations for high Reynolds-number flows. The results showed that both the pressure rise and the efficiency were observed to be higher in the smaller-gap cases. Comparisons between the results of two gaps, 35%ca and 3.5%ca, are highlighted and further analysis at a specific flow coefficient showed that the increase of the stage performance was contributed to by the enhancement of rotor loading and the suppression to the flow separation of the stator. Correspondingly, the increases of the total pressure rise on the rotor and the stator outlets were observed to be 0.5% and 4.3%, respectively. Although the increase on the rotor outlet is much lower than that on the stator outlet, its significance is that a higher level of static pressure is formed near the hub of the gap, which, thus, reduces the adverse pressure gradient of this region in the stator passage. This improvement suppresses the flow separation near the hub of the stator and, thereby, results in a considerable increase to the pressure rise on the stator outlet as a consequence. The effect of the gap on unsteady pressure fluctuation is also presented.
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Wajnert, Dawid, i Bronisław Tomczuk. "Simulations of Transients in a Four-Pole Magnetic Bearing with Permanent Magnets". Sensors 24, nr 5 (22.02.2024): 1402. http://dx.doi.org/10.3390/s24051402.
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This paper presents the design of and transient time simulations for a four-pole magnetic bearing with permanent magnets. The usage of permanent magnets reduces the consumption of electric energy in comparison to a traditional active magnetic bearing. Permanent magnets are installed in the yoke of the stator core to limit the cross-coupling of the magnetic flux generated by the windings. The first part of this paper presents the design of the magnetic bearing and its finite-element model, while the second part describes the field-circuit indirectly coupled finite-element model for the transient time simulation. The presented simulation model was used to calculate the transient response for the rotor lifting from the starting position, the step change in the rotor position and the change in the rotor position under an external impact force applied along the y-axis.
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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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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.
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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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Sebastian, Ekop Ubong, Ekom Enefiok Okpo i Imo Edwin Nkan. "Dynamic Simulation and Analysis of Three Phase Induction Motor for Faults Detection using Matlab/Simulink". Journal of Engineering Research and Reports 26, nr 11 (19.11.2024): 286–303. http://dx.doi.org/10.9734/jerr/2024/v26i111331.
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The dynamic simulation of three-phase induction motors under fault conditions is essential for understanding and mitigating the impacts of electrical faults on motor performance. This study aims to simulate and analyze the impact of electrical faults on three-phase induction motors to improve fault detection and isolation strategies. Utilizing MATLAB/Simulink software, the behavior of three-phase induction motors under both symmetrical and unsymmetrical faults is modeled and analyzed. The motor’s baseline parameters, include 3 Amps rated power and speed of 1500 RPM. Symmetrical faults, such as line-to-line-to-line (L-L-L), and unsymmetrical faults, like single-phase to ground faults, were simulated to observe their effects on motor operation. The d-q model was used to simulate motor dynamics, employing a block model approach to resolve reference frame theory issues. Major parameters analyzed include rotor speed, electromagnetic torque, and stator current. Through detailed simulations, key performance indicators such as torque fluctuations, current spikes, and decreases in rotor speed are examined. At 1.5 seconds, when the fault was introduced, the rotor speed, electromagnetic torque, and stator current were all affected. For instance, during a symmetrical fault, the rotor speed dropped from 1500 RPM to 1200 RPM, electromagnetic torque declined to -12 Nm, and the stator current increased to 7 Amps from the rated 3 Amps. Under an unsymmetrical single-phase-to-ground fault at the same instant, rotor speed decreased from 1500 RPM to 1400 RPM, electromagnetic torque declined to -12 Nm with greater distortion, and the stator current in the affected phases rose to 7 Amps from the rated 3 Amps. These results underscore the importance of robust fault detection and isolation mechanisms to enhance motor reliability and longevity. This work significantly contributes to engineering by offering validated simulation models and insights into parameter sensitivity, serving as both an educational resource and a foundation for advanced fault detection system development. The findings are applicable in academic research and industrial contexts, providing guidance for improving motor design and fault management strategies.