Articles de revues : « Rotor Modelling »

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Fletcher, T. M., et R. E. Brown. « Modelling the interaction of helicopter main rotor and tail rotor wakes ». Aeronautical Journal 111, n^o 1124 (octobre 2007) : 637–43. http://dx.doi.org/10.1017/s0001924000004814.

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Abstract The mutual interaction between the main rotor and tail rotor wakes is central to some of the most problematic dynamic phenomena experienced by helicopters. Yet achieving the ability to model the growth and propagation of helicopter rotor wakes with sufficient realism to capture the details of this interaction has been a significant challenge to rotorcraft aerodynamicists for many decades. A novel computational fluid dynamics code tailored specifically for rotorcraft applications, the vorticity transport model, has been used to simulate the interaction of the rotors of a helicopter with a single main rotor and tail rotor in both hover and low-speed quartering flight, and with the tail rotor rotating both top-forward and top-aft. The simulations indicate a significant level of unsteadiness in the performance of both main and tail rotors, especially in quartering flight, and a sensitivity to the direction of rotation of the tail rotor. Although the model thus captures behaviour that is similar to that observed in practice, the challenge still remains to integrate the information from high fidelity simulations such as these into routine calculations of the flight dynamics of helicopters.

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Flannigan, Callum, James Carroll et William Leithead. « Operations expenditure modelling of the X-Rotor offshore wind turbine concept ». Journal of Physics : Conference Series 2265, n^o 3 (1 mai 2022) : 032054. http://dx.doi.org/10.1088/1742-6596/2265/3/032054.

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Abstract O&M of an offshore wind farm is becoming increasingly challenging as farms are being commissioned further from shore. Weather windows are more difficult to navigate leading to longer downtime for turbines. The X-Rotor offshore wind turbine concept directly tackles these O&M challenges by, amongst other advantages, removing the requirements for components that have traditionally contributed high failure rates, repair times and downtimes, and by placing the heavy and expensive machinery closer to sea level. The turbine also benefits from having modular small rotors that can be quickly replaced and repaired onshore, and being able to operate at reduced capacity when there are failures in the modular rotors. This paper presents the StrathX-OM OpEx model. This model features changes to OpEx modelling that will allow for comprehensive analysis of the operations and maintenance costs for a wind farm made up of radical X-Rotor wind turbines with the flexibility to handle changing designs as the technology progresses. The calculation of lifetime O&M costs for a wind farm 100 km from shore showed that the X-Rotor has lower O&M costs than conventional HAWTs for an established design. A sensitivity study on the estimated failure rates of X-Rotor is also presented. This shows that even with significantly over-estimated failure rates the X-Rotor would still be competitive in today’s market.

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Ilie, K., et A. Subic. « Parametric modelling of helical rotors for efficient design of twin-screw superchargers ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 221, n^o 2 (1 février 2007) : 267–72. http://dx.doi.org/10.1243/0954406jmes421ft.

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The parametric three-dimensional geometric model of twin-screw supercharger rotors of any aspect ratio was developed. For model validation through visualization, computer-aided design (CAD) rotor models with scalable data were generated in commercial CAD software and calibrated experimentally by laser Doppler velocimetry (LDV) tests. Calibrated rotor profile data can be transferred into CAD-CFD interface for flow simulation for performance optimization.

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Park, J. S., et S. N. Jung. « Comprehensive multibody dynamics analysis for rotor aeromechanics predictions in descending flight ». Aeronautical Journal 116, n^o 1177 (mars 2012) : 229–49. http://dx.doi.org/10.1017/s0001924000006813.

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AbstractThis paper studies the rotor aeromechanics in descending flight using a nonlinear flexible multibody dynamic analysis code, DYMORE. A freewake model is included in DYMORE to improve the rotor wake modelling. The wind-tunnel test data of the Higher-harmonic Aeroacoustics Rotor Test (HART) II rotor, with and without higher harmonic pitch control (HHC), and the flight test data of the full-scale utility helicopter rotor in descent are used for the aeromechanics correlation at an advance ratio of 0·15. The blade-vortex interaction (BVI) airloads are reasonably predicted for both the HART II and utility helicopter rotors, although some BVI peaks are missed on the advancing sides for both the rotors. The flap deflections and elastic torsion deformations at the blade tip are fairly correlated against the measured data of the HART II rotor. The correlation of blade structural moments for both HART II and utility helicopter rotors are not as good as the lift predictions; however, a reasonable prediction is obtained for the utility helicopter rotor.

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Bartlett, H., et R. Whalley. « Distributed rotor dynamics ». Proceedings of the Institution of Mechanical Engineers, Part I : Journal of Systems and Control Engineering 212, n^o 4 (1 juin 1998) : 249–65. http://dx.doi.org/10.1243/0959651981539442.

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The modelling, simulation and analysis of powered rotors with ‘long’ thin shells is investigated. General results enabling the prediction of the torsional vibrational signature of high-speed assemblies under acceleration or braking conditions are outlined. It is demonstrated that simulated response characteristics can be easily obtained and the effect of varying the rotor geometry can be routinely accommodated. Finally, a rotor for a high-speed paper manufacturing unit is investigated and the torsional behaviour of the assembly is computed. The volatile transient conditions presented are commented upon.

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Torija, Antonio J., Zhengguang Li et Paruchuri Chaitanya. « Psychoacoustic modelling of rotor noise ». Journal of the Acoustical Society of America 151, n^o 3 (mars 2022) : 1804–15. http://dx.doi.org/10.1121/10.0009801.

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The aviation sector is rapidly evolving with more electric propulsion systems and a variety of new technologies of vertical take-off and landing manned and unmanned aerial vehicles. Community noise impact is one of the main barriers for the wider adoption of these new vehicles. Within the framework of a perception-driven engineering approach, this paper investigates the relationship between sound quality and first order physical parameters in rotor systems to aid design. Three case studies are considered: (i) contra-rotating versus single rotor systems, (ii) varying blade diameter and thrust in both contra-rotating and single rotor systems, and (iii) varying rotor–rotor axial spacing in contra-rotating systems. The outcomes of a listening experiment, where participants assessed a series of sound stimuli with varying design parameters, allow a better understanding of the annoyance induced by rotor noise. Further to this, a psychoacoustic annoyance model optimised for rotor noise has been formulated. The model includes a novel psychoacoustic function to account for the perceptual effect of impulsiveness. The significance of the proposed model lies in the quantification of the effects of psychoacoustic factors, such as loudness as the dominant factor, and also tonality, high frequency content, temporal fluctuations, and impulsiveness on rotor noise annoyance.

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Dutt, J. K., et H. Roy. « Viscoelastic modelling of rotor—shaft systems using an operator-based approach ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 225, n^o 1 (11 juin 2010) : 73–87. http://dx.doi.org/10.1243/09544062jmes2064.

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Damping exists in every material in varying degrees, so materials in general are viscoelastic in nature. Energy storage, as well as dissipation in varying degrees, accompanies every time-varying deformation, with the effect that stress and strain in a material get out of phase. This work presents the development of equations of motion of a rotor—shaft system with a viscoelastic rotor after discretizing the system into finite elements. Subsequently, these equations are used to study the dynamics of the rotor—shaft system in terms of stability limit of spin speed and time response of a disc as a result of unbalance. The primary inspiration for a viscoelastic model arises from the need to capture the influence of broad band spectral behaviour of rotor—shaft materials, primarily polymers and polymer composites, which are principally the materials of light rotors, on the dynamics of rotor—shaft system. For this, the material constitutive relationship has been represented by a differential time operator. Use of operators enables one to consider general linear viscoelastic behaviours, represented in the time domain by multi-element (three, four, or higher elements) spring—dashpot models or internal variable models, for which, in general, instantaneous stress and its derivatives are proportional to instantaneous strain and its derivatives. Again such representation is fairly generic, in a sense that the operator may be suitably chosen according to the material model to obtain the equations of motion of a rotor—shaft system. The equations so developed may be easily used to find the stability limit speed of a rotor—shaft system as well as the time response when the rotor—shaft system is subjected to any dynamic forcing function.

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Cîrciumaru, G., R.-A. Chihaia, N. Tănase, L.-A. El-Leathey et A. Voina. « Increasing energy efficiency of counter-rotating wind turbines by experimental modelling ». IOP Conference Series : Materials Science and Engineering 1235, n^o 1 (1 mars 2022) : 012064. http://dx.doi.org/10.1088/1757-899x/1235/1/012064.

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Abstract With the significant advance in exploiting wind energy, there has been a shift in research from the study of conventional systems to the study of counter-rotating systems due to additional energy input of the second rotor. The paper presents the results of the research on achieving an increase in the energy efficiency of counter-rotating wind power conversion systems. For this purpose, there have been designed different sizes of wind rotors, were 3D printed and tested in an open-circuit aerodynamic tunnel for different wind velocities and axial distances between rotors. The constructive design consisting of a smaller diameter front rotor and a larger rear rotor was chosen. The individual wind rotors were used to configure two experimental models of counter-rotating wind systems. The testing results analysis and interpretation enabled the establishing of the design and operating conditions that provide the highest power extracted from wind at 10 m/s velocity. A higher efficiency of the wind turbine system is achieved for a lower ratio between the front and rear turbines. In the case of the analysed experimental models, an increase in system efficiency of 49.14% is achieved for a 0.845 diameter ratio, and of 39.02% for 0.945 diameter ratio, respectively.

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Ellin, Lt Cdr A. D. S. « Lynx Main Rotor/Tail Rotor Interactions : Mechanisms and Modelling ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 208, n^o 2 (juillet 1994) : 115–28. http://dx.doi.org/10.1243/pime_proc_1994_208_261_02.

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A flight trial has been conducted by the Defence Research Agency (DRA) Bedford using a Lynx AH Mk5 helicopter fitted with an instrumented tail rotor to collect data on tail rotor aerodynamic performance. The analysis carried out to date has concentrated on the effects of main rotor wake interactions on the tail rotor. This paper describes the trial and the analysis in broad outline and discusses in detail mechanisms to explain three out of the six main rotor/tail rotor interactions found. The modelling of these effects to improve the fidelity of ground-based flight simulation is also covered.

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Chen, Jiajia, Fanfu Yin, Xinkai Li, Zhaoliang Ye, Wei Tang, Xin Shen et Xiaojiang Guo. « Unsteady aerodynamic modelling for dual-rotor wind turbines with lifting surface method and free wake model ». Journal of Physics : Conference Series 2265, n^o 4 (1 mai 2022) : 042055. http://dx.doi.org/10.1088/1742-6596/2265/4/042055.

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Abstract A time-marching aerodynamic model for dual-rotor wind turbines (DRWT) is presented with the lifting surface method and free wake model. The performance of a reference DRWT by two axial connected NREL 5MW wind turbines is calculated to verify the algorithm. The output converges with remarkable oscillation. Free wakes swell under the coupling effect. The accumulated power of DRWT outranges single-rotor wind turbine (SRWT) by a limited extent under certain operating conditions. The front rotor (FR) produces the major portion of the power, especially for low inflow velocity. The unsteadiness of performance and spanwise load is further investigated, and the result shows that the power output of the rear rotor (RR) undergoes greater fluctuation than FR. The rotor-rotor induction strengthens both the rotors’ performance before they align and weakens it when they rotate away. The additional disturbance caused by FR’s tip vortices acts negatively on RR’s torque by upwashing the blade tip.

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Staśko, T., M. Majkut, S. Dykas et K. Smołka. « CFD modelling of a fan with a cycloidal rotor ». Journal of Physics : Conference Series 2367, n^o 1 (1 novembre 2022) : 012005. http://dx.doi.org/10.1088/1742-6596/2367/1/012005.

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Abstract Despite the wide possibilities of using a cycloidal rotor in the form of propulsion systems for unmanned aerial vehicles (UAV), cycloidal propellers for sea-going ships, rotors of wind turbines or sea or river cycloidal energy converters, there is practically no research on the use of this solution in the form of a cycloidal rotor fan (CRF) for HVAC (heat, ventilation & air conditioning) applications. The main features of such a machine, compared to conventional solutions, is a possibility of changing the flow direction only by changing pitch angles of the rotor blades. This study analysed two variants of the fan, first equipped with an asymmetrical CLARK Y profile, and other with a symmetrical NACA0012. Numerical simulation of cycloidal rotor fan developed in Ansys CFX was presented, that enables the simulation of fan operation. The results obtained from CFD for both variants were compared with those obtained during experimental measurements made with the use of Laser Doppler Anemometry (LDA). The comparison showed good agreement between the numerical analysis and the performed experiment. Despite the operation based on the same cycloidal regulation settings and rotation speed, the fan equipped with symmetrical blades slightly more curved the flow angle than the asymmetrical one.

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Hajžman, Michal, Miroslav Balda, Petr Polcar et Pavel Polach. « Turbine Rotor Dynamics Models Considering Foundation and Stator Effects ». Machines 10, n^o 2 (22 janvier 2022) : 77. http://dx.doi.org/10.3390/machines10020077.

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The paper deals with the modelling of turbine rotors, including a foundation and stator parts, and with their dynamic analysis. The dynamics of turbines can be strongly influenced by the effects of a rotor foundation, and therefore suitable modelling approaches should be developed to obtain proper analysis tools. The standard methods for the modelling of rotating shafts are summarized in the paper, and two approaches to including foundation effects into dynamic models are introduced. The approach based on the dynamic compliance of the foundation with respect to the rotor angular velocity is compared with the approach based on the modal synthesis of rotor and foundation models. The calculation of modal properties is then demonstrated, and the characteristics of both presented methods are discussed. A comparison of the steady-state dynamic response calculated using both methods is shown. It can be concluded that both approaches can be advantageously used for several analyses, and our final recommendations are given in the conclusions.

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Penny, J. E. T., et Michael I. Friswell. « Simplified Modelling of Rotor Cracks ». Key Engineering Materials 245-246 (juillet 2003) : 223–32. http://dx.doi.org/10.4028/www.scientific.net/kem.245-246.223.

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Castillo-Rivera, Salvador, et Maria Tomas-Rodriguez. « Description of a Dynamical Framework to Analyse the Helicopter Tail Rotor ». Dynamics 1, n^o 2 (12 octobre 2021) : 171–80. http://dx.doi.org/10.3390/dynamics1020010.

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In this work, a tail rotor is modelled with the aid of a multibody software to provide an alternative tool in the field of helicopter research. This advanced application captures the complex behaviour of tail rotor dynamics. The model has been built by using VehicleSim software (Version 1.0, Mechanical Simulation Corporation, Ann Arbor, MI, USA) specialized in modelling mechanical systems composed of rigid bodies. The dynamic behaviour and the control action are embedded in the code. Thereby, VehicleSim does not need an external link to another software package. The rotors are articulated, the tail rotor considers flap and feather degrees of freedom for each of the equispaced blades and their dynamic couplings. Details on the model’s implementation are derived, emphasising the modelling aspects that contribute to the coupled dynamics. The obtained results are contrasted with theoretical approaches and these have displayed to agree with the expected behaviour. This rotorcraft model helps to study the performance of a tail rotor under certain dynamic conditions.

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Brown, Richard E., et Glen R. Whitehouse. « Modelling Rotor Wakes in Ground Effect ». Journal of the American Helicopter Society 49, n^o 3 (1 juillet 2004) : 238–49. http://dx.doi.org/10.4050/jahs.49.238.

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David, B., T. Sapir, A. Nir et Z. Tadmor. « Modelling Twin Rotor Mixers and Extruders ». International Polymer Processing 5, n^o 3 (septembre 1990) : 155–63. http://dx.doi.org/10.3139/217.900155.

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David, B., T. Sapir, A. Nir et Z. Tadmor. « Modelling Twin Rotor Mixers and Extruders ». International Polymer Processing 7, n^o 3 (septembre 1992) : 204–11. http://dx.doi.org/10.3139/217.920204.

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Orlikowski, Cezary, et Rafał Hein. « Modelling of Geared Multi-Rotor System ». Solid State Phenomena 198 (mars 2013) : 669–74. http://dx.doi.org/10.4028/www.scientific.net/ssp.198.669.

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In this paper the method of modelling a speed-varying geared rotor system is presented. The proposed approach enables us to obtain an accurate low-order lumped parameter representation of the investigated system. The final model consists of reduced modal models of an undamped beam/torsional shaft system as well as a spatially lumped model of other linear and nonlinear phenomena including gear mesh interaction.

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Chalupa, Petr, Jan Přikryl et Jakub Novák. « Modelling of Twin Rotor MIMO System ». Procedia Engineering 100 (2015) : 249–58. http://dx.doi.org/10.1016/j.proeng.2015.01.365.

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Shevchenko, S. S. « Mathematical Modelling of Dynamic System Rotor – Groove Seals ». Èlektronnoe modelirovanie 43, n^o 3 (4 juin 2021) : 17–35. http://dx.doi.org/10.15407/emodel.43.03.017.

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Groove seals are considered as hydrostatic bearings that capable of effectively damping rotor vibrations. In order to determine the dynamic characteristics, a model of the rotor–groove seals system is considered. The radial forces and moments in groove seals had been estimated. Expressions of joint radial-angular rotor vibrations in groove seals had been obtained. Formulas had been proposed for constructing amplitude and phase frequency characteristics. An example of calculating the dynamic characteristics of a centrifugal machine rotor model is given.

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Kaleta, Jiří, Josef Michl, Cécile Mézière, Sergey Simonov, Leokadiya Zorina, Pawel Wzietek, Antonio Rodríguez-Fortea, Enric Canadell et Patrick Batail. « Gearing motion in cogwheel pairs of molecular rotors : weak-coupling limit ». CrystEngComm 17, n^o 41 (2015) : 7829–34. http://dx.doi.org/10.1039/c5ce01372k.

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Investigation of the rotor dynamics by X-ray diffraction, spin–lattice relaxation, and DFT modelling of the two rotational barriers in arrays of rod-like molecules with 1,3-bis(ethynyl)bicyclo[1.1.1]pentane rotators conclude to gearing motion between two rotors in a pair.

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McMorland, Jade, Paul Pirrie, Maurizio Collu, David McMillan, James Carroll, Andrea Coraddu et Peter Jamieson. « Operation and Maintenance Modelling for Multi Rotor Systems : Bottlenecks in Operations ». Journal of Physics : Conference Series 2265, n^o 4 (1 mai 2022) : 042059. http://dx.doi.org/10.1088/1742-6596/2265/4/042059.

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Abstract As the installed capacity of individual turbines increases, so do costs associated with manufacture and maintenance. One proposed solution to this problem is the Multi-Rotor System (MRS) which utilises many small rotors to yield the same energy capture as a single large turbine. The operational advantage of the MRS is the built in redundancy between rotors on the same structure. However, despite this advantage, an increase in number of components is likely to result in an increase in transfers. This work examines the balance between additional crew and vessel requirements for such a structure against the expected savings in downtime due to redundancy and small rotor power rating. Three scenarios are analysed to determine the distribution of the failures which contribute to downtime. The study aims to find the optimal vessel fleet which limits downtime without drastically increasing direct operational expenditure (OpEx). As site size increases, the impact of global failures, which shut down the whole asset, is lessened. However, there is a significant increase in the number of vessels required to reduce downtime to <10% of the total OpEx. While a large fleet can offer significant downtime savings, there are practical limitations and challenges which must be acknowledged.

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Sałaciński, Michał, Rafał Kowalski, Michał Szmidt et Sławomir Augustyn. « A New Approach to Modelling and Testing the Fatigue Strength of Helicopter Rotor Blades during Repair Process ». Fatigue of Aircraft Structures 2019, n^o 11 (1 décembre 2019) : 56–67. http://dx.doi.org/10.2478/fas-2019-0006.

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AbstractThe fatigue test was carried out on an element of a rotor blade removed from the Mi-2 helicopter. The purpose of the test was to check the fatigue strength of the repaired rotor blade. Metal composite rotor blades have a metal spar in the form of a box and the trailing sections in the form of metallic honeycomb sandwich panels. The trailing sections are bonded to the spar. The repair had been carried out at the point where the trailing section became debonded from the spar at the Air Force Institute of Technology in Warsaw using a methodology developed for carrying out repairs of rotor blades’ damage. All types of the Mi family helicopters are equipped with metal composite rotors blades. Depending on MTOW (Maximum Take-Off Weight) and destination of helicopters, blades differ in dimensions, but their design solutions are practically the same. For this reason, the developed repair methodology can be used for all characteristic rotor blades structures for Mi helicopters. The fatigue test was performed at the Łukasiewicz - Institute of Aviation in Warsaw, using a hydraulically driven fatigue machine. The fatigue test was carried out by performing over 1.1 million load cycles. In repair places, upon completion of fatigue testing, no damage was found.

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Spagnol, Joseph, Helen Wu et Chunhui Yang. « Application of Non-Symmetric Bending Principles on Modelling Fatigue Crack Behaviour and Vibration of a Cracked Rotor ». Applied Sciences 10, n^o 2 (20 janvier 2020) : 717. http://dx.doi.org/10.3390/app10020717.

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Many studies on cracked rotors developed crack breathing models that assume that the neutral axis of bending always remains horizontal for simplification. These models may generate significant discrepancies and thus there is a need to develop more sophisticated models to look into the shifting of the neutral axis for a cracked rotor. Herein, a case study on the shifting of the neutral axis for a cracked rotor is firstly performed by using a three-dimensional finite element model to confirm that the neutral axis becomes inclined as the cracked rotor rotates. In response to this finding, non-symmetric bending principles are used to develop a new crack breathing model which has the advantage of being able to numerically calculate the inclination angle of the neutral axis. When compared to an existing crack model in the literature that assumes that the neutral axis remains horizontal (HNA model), the proposed model is relatively less stiff in bending as a result of an overall lower area moment of inertia. Using the harmonic balance method, a two-dimensional finite element vibration model of a cracked rotor was devised by employing the proposed crack breathing model and the HNA model for validation. It can be found that the vibration amplitudes of the first three frequency components are similar between the two models for shallow cracks and significantly differed for deep cracks. This result highlights the potential of the proposed model for modelling and detecting mid-to-late-stage cracks in rotors.

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Murakami, Y., et S. S. Houston. « Dynamic inflow modelling for autorotating rotors ». Aeronautical Journal 112, n^o 1127 (janvier 2008) : 47–53. http://dx.doi.org/10.1017/s0001924000001986.

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Abstract The dynamic inflow model is a powerful tool for predicting the induced velocity distribution over a rotor disc. On account of its closed form and simplicity, the model is especially practical for studying flight mechanics or for designing control systems for helicopters. Scant attention has, however, been paid so far in utilising the dynamic inflow model to analyse an autorotating rotor, which is different from a powered rotor in the geometric relation between the direction of the inflow and the rotor disc. Autorotation is an abnormal condition for helicopters, but for gyroplanes it is the normal mode of operation. Therefore the theoretical discussion on an autorotating rotor is of importance not only to improve the understanding of present gyroplanes, but also in the development of new gyroplanes and to analyse the windmill-brake state of helicopters. Dynamic inflow modelling is reviewed from first principles, and this identifies a modification to the mass flow parameter. A qualitative assessment of this change indicates that it is likely to have a negligible impact on the trim state of rotorcraft in autorotation, but a significant effect on the dynamic inflow modes in certain flight conditions. This is confirmed by numerical simulation, although considerable differences only become apparent for steep descents with low forward speed. It is concluded that while modification of the mass flow parameter is perhaps mathematically accurate, for practical purposes it is required only in a limited area of the flight envelope of autorotating rotorcraft.

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Jiffri, S., S. D. Garvey et A. I. J. Rix. « Enriching balancing information using the unbalance covariance matrix ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 223, n^o 8 (15 avril 2009) : 1815–26. http://dx.doi.org/10.1243/09544062jmes1181.

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Traditionally, rotor balancing is performed based only on vibration readings from either a balancing machine or from a machine in which the rotor is being balanced in-situ. These readings cannot reflect the complete state of unbalance in the rotor. The reason for this is that higher frequency modes do not make a significant contribution to response in any one operating condition. The resolution of measuring instrumentation is always limited and, as demands grow for ever-improved balance quality, this instrumentation struggles more and more with reducing signal-to-noise ratios. When balance corrections are made to a rotor based only on these vibration readings, the components of unbalance that tend to excite only the higher modes of the original configuration can make a significant contribution to response if the properties of the stator change. This article presents a novel approach to robust balancing. It relies on the use of additional information in the form of a rotor unbalance covariance matrix. In theory, this covariance matrix could be obtained if a large sample from the population of all rotors of this type could be tested in a very high-quality (and high-speed) balancing machine. This suggestion is impracticable in all real situations. However, it is entirely conceivable that modelling of the manufacturing processes used to create the rotor could deliver this covariance matrix. This article begins by illustrating how such a covariance matrix might be obtained from modelling and then goes on to explain how the information within the covariance matrix can be combined with a set of measurements from a specific rotor to provide an improved estimate of the actual state of unbalance on that rotor. Examples are included to demonstrate the proposed robust balancing method.

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Roney, Caroline H., Jason D. Bayer, Sohail Zahid, Marianna Meo, Patrick M. J. Boyle, Natalia A. Trayanova, Michel Haïssaguerre, Rémi Dubois, Hubert Cochet et Edward J. Vigmond. « Modelling methodology of atrial fibrosis affects rotor dynamics and electrograms ». EP Europace 18, suppl_4 (1 décembre 2016) : iv146—iv155. http://dx.doi.org/10.1093/europace/euw365.

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Aims Catheter ablation is an effective technique for terminating atrial arrhythmia. However, given a high atrial fibrillation (AF) recurrence rate, optimal ablation strategies have yet to be defined. Computer modelling can be a powerful aid but modelling of fibrosis, a major factor associated with AF, is an open question. Several groups have proposed methodologies based on imaging data, but no comparison to determine which methodology best corroborates clinically observed reentrant behaviour has been performed. We examined several methodologies to determine the best method for capturing fibrillation dynamics. Methods and results Patient late gadolinium-enhanced magnetic resonance imaging data were transferred onto a bilayer atrial computer model and used to assign fibrosis distributions. Fibrosis was modelled as conduction disturbances (lower conductivity, edge splitting, or percolation), transforming growth factor-β1 ionic channel effects, myocyte-fibroblast coupling, and combinations of the preceding. Reentry was induced through pulmonary vein ectopy and the ensuing rotor dynamics characterized. Non-invasive electrocardiographic imaging data of the patients in AF was used for comparison. Electrograms were computed and the fractionation durations measured over the surface. Edge splitting produced more phase singularities from wavebreaks than the other representations. The number of phase singularities seen with percolation was closer to the clinical values. Addition of fibroblast coupling had an organizing effect on rotor dynamics. Simple tissue conductivity changes with ionic changes localized rotors over fibrosis which was not observed with clinical data. Conclusion The specific representation of fibrosis has a large effect on rotor dynamics and needs to be carefully considered for patient specific modelling.

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Jamieson, Peter. « Top-level rotor optimisations based on actuator disc theory ». Wind Energy Science 5, n^o 2 (23 juin 2020) : 807–18. http://dx.doi.org/10.5194/wes-5-807-2020.

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Abstract. Ahead of the elaborate rotor optimisation modelling that would support detailed design, it is shown that significant insight and new design directions can be indicated with simple, high-level analyses based on actuator disc theory. The basic equations derived from actuator disc theory for rotor power, axial thrust and out-of-plane bending moment in any given wind condition involve essentially only the rotor radius, R, and the axial induction factor, a. Radius, bending moment or thrust may be constrained or fixed, with quite different rotor optimisations resulting in each case. The case of fixed radius or rotor diameter leads to conventional rotor design and the long-established result that power is maximised with an axial induction factor, a=1/3. When the out-of-plane bending moment is constrained to a fixed value with axial induction variable in value (but constant radially) and when rotor radius is also variable, an optimum axial induction of 1∕5 is determined. This leads to a rotor that is expanded in diameter 11.6 %, gaining 7.6 % in power and with thrust reduced by 10 %. This is the low-induction rotor which has been investigated by Chaviaropoulos and Voutsinas (2013). However, with an optimum radially varying distribution of axial induction, the same 7.6 % power gain can be obtained with only 6.7 % expansion in rotor diameter. When without constraint on bending moment, the thrust is constrained to a fixed value, and the power is maximised as a→0, which for finite power extraction would require R→∞. This result is relevant when secondary rotors are used for power extraction from a primary rotor. To avoid too much loss of the source power available from the primary rotor, the secondary rotors must operate at very low induction factors whilst avoiding too high a tip speed or an excessive rotor diameter. Some general design issues of secondary rotors are explored. It is suggested that they may have the most practical potential for large vertical axis turbines avoiding the severe penalties on drivetrain cost and weight implicit in the usual method of power extraction from a central shaft.

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Whalley, R., et A. A-Ameer. « The computation of torsional, dynamic stresses ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 223, n^o 8 (15 avril 2009) : 1799–814. http://dx.doi.org/10.1243/09544062jmes1215.

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The torsional dynamics of spatially dispersed, mechanical, power transmission system models are considered. Distributed—lumped parameter modelling methods are employed in the analysis of configurations comprising rotors, bearings, and relatively slender shaft arrangements. Analysis procedures enabling the computation of the torsional shear stress and velocity response of these drive systems are outlined and block diagram representations are formulated. The transient characteristics for shaft—rotor arrangements following deterministic input changes are computed. Typical rotor—shaft assemblies are investigated, illustrating thereby the procedures involved. Graphical results and comparative studies are presented and the generality of the techniques detailed is commented upon.

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Fieux, Gauthier A., Nicola Y. Bailey et Patrick S. Keogh. « Internal Rotor Actuation and Magnetic Bearings for the Active Control of Rotating Machines ». Actuators 11, n^o 2 (16 février 2022) : 57. http://dx.doi.org/10.3390/act11020057.

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Passive rotors are often limited in rotational speed due to bearing constraints, stability and excessive vibration levels. To address the vibration issue, Active Magnetic Bearings (AMBs) levitating the rotor with a magnetic field can be used. They offer a clearance and variable stiffness and damping to the rotor support, which help to mitigate greatly the vibration issue. However, they are also limited at large rotational speed because of the high frequency control force required to levitate the rotor safely. To overcome the frequency limitation, a dual AMBs/internal bending control concept is investigated with associated modelling and control algorithms. This approach is examined in simulation with a 19 kg rotor running up to 10,000 RPM, where three resonance frequencies are present at 2700, 5300, and 9300 RPM, with the first resonant frequency being the most strongly excited. Using internal rotor bending control, a maximum radial displacement of 15 μm for the rotor mid-point is achieved, which gives a reduction in vibration amplitude of 45% compared to the case of no control. Variations of the algorithm are presented and discussed, showing the potential of the proposed approach.

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Abà, Anna, Federico Barra, Pierluigi Capone et Giorgio Guglieri. « Mathematical Modelling of Gimballed Tilt-Rotors for Real-Time Flight Simulation ». Aerospace 7, n^o 9 (28 août 2020) : 124. http://dx.doi.org/10.3390/aerospace7090124.

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This paper introduces a novel gimballed rotor mathematical model for real-time flight simulation of tilt-rotor aircraft and other vertical take-off and landing (VTOL) concepts, which improves the previous version of a multi-purpose rotor mathematical model developed by ZHAW and Politecnico di Torino as part of a comprehensive flight simulation model of a tilt-rotor aircraft currently implemented in the Research and Didactics Simulator of ZHAW and used for research activities such as handling qualities studies and flight control systems development. In the novel model, a new formulation of the flapping dynamics is indroduced to account for the gimballed rotor and better suit current tilt-rotor designs (XV-15, V-22, AW-609). This paper describes the mathematical model and provides a generic formulation as well as a specific one for 3-blades proprotors. The method expresses the gimbal attitude but also considers the variation of each blade’s flapping due to the elasticity of the blades, so that the rotor coning angle can be represented. A validation of the mathematical model is performed against the available literature on the XV-15 Tilt-rotor aircraft and a comparison between the previous model is provided to show the improvements achieved. The results show a good correlation between the model and the reference data and the registered performance allow real-time flight simulation with pilot and hardware in the loop.

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Ziese, Christian, Cornelius Irmscher, Steffen Nitzschke, Christian Daniel et Elmar Woschke. « Run-Up Simulation of a Semi-Floating Ring Supported Turbocharger Rotor Considering Thrust Bearing and Mass-Conserving Cavitation ». Lubricants 9, n^o 4 (16 avril 2021) : 44. http://dx.doi.org/10.3390/lubricants9040044.

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The vibration behaviour of turbocharger rotors is influenced by the acting loads as well as by the type and arrangement of the hydrodynamic bearings and their operating condition. Due to the highly non-linear bearing behaviour, lubricant film-induced excitations can occur, which lead to sub-synchronous rotor vibrations. A significant impact on the oscillation behaviour is attributed to the pressure distribution in the hydrodynamic bearings, which is influenced by the thermo-hydrodynamic conditions and the occurrence of outgassing processes. This contribution investigates the vibration behaviour of a floating ring supported turbocharger rotor. For detailed modelling of the bearings, the Reynolds equation with mass-conserving cavitation, the three-dimensional energy equation and the heat conduction equation are solved. To examine the impact of outgassing processes and thrust bearing on the occurrence of sub-synchronous rotor vibrations separately, a variation of the bearing model is made. This includes run-up simulations considering or neglecting thrust bearings and two-phase flow in the lubrication gap. It is shown that, for a reliable prediction of sub-synchronous vibrations, both the modelling of outgassing processes in hydrodynamic bearings and the consideration of thrust bearing are necessary.

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Liu, Jing, Yajun Xu et Yimin Shao. « Dynamic modelling of a rotor-bearing-housing system including a localized fault ». Proceedings of the Institution of Mechanical Engineers, Part K : Journal of Multi-body Dynamics 232, n^o 3 (27 octobre 2017) : 385–97. http://dx.doi.org/10.1177/1464419317738427.

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An in-depth understanding of the dynamic characteristics through rotor-bearing-housing systems is very valuable for fault detection and diagnosis applications of rotating machines such as high-speed spindle, roll mill, gearbox, engines, etc. A new vibration model of a rotor-bearing-housing system considering the rotor compliance, elastic interface between the housing and outer race, housing compliance, and time-dependent excitations introduced by a localized fault on the inner and outer races of an inherent ball bearing is proposed in this work. An analytical method for calculating the time-dependent excitations including the time-dependent displacement excitation and contact stiffness coefficient between the ball and fault edges is presented. Differences between vibration responses of a rotor-bearing-housing system from the proposed model and the previous model without the rotor compliance in the literature are discussed. The presented model is used to discuss the influences of all the rotor compliance, housing compliance, and fault sizes on the races of the inherent ball bearing on the vibration responses and vibration transmission characteristics through the rotor-bearing-housing system, which cannot be formulated by the current dynamic models in the listed references. An experimental study is introduced to validate the presented model. The results show that the rotor compliance and time-dependent contact stiffness coefficient caused by the fault have great influence on the dynamic characteristics through the rotor-bearing-housing system. It also seems that the developed method can provide a new vibration modelling method for the vibration analysis for a rotor-bearing-housing system with and without the faults.

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Xia, Z. P., Z. Q. Zhu, P. J. Monkhouse et D. Howe. « Electromagnetic modelling of a rolling rotor actuator ». IEEE Transactions on Magnetics 29, n^o 6 (novembre 1993) : 3153–55. http://dx.doi.org/10.1109/20.281120.

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Ganguly, Krishanu, Saurabh Chandraker et Haraprasad Roy. « A review on modelling and dynamic analysis of viscoelastic rotor systems ». Aircraft Engineering and Aerospace Technology 94, n^o 5 (11 janvier 2022) : 734–44. http://dx.doi.org/10.1108/aeat-12-2020-0292.

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Purpose The purpose of this study is to bring down collective information about various issues encountered in modelling of rotor systems. Design/methodology/approach The most important and basic part of “rotor dynamics” is the study related to its different modelling techniques which further involves the analysis of shaft for understanding the system potential, competence and reliability. The issues addressed in this study are classified mainly into two parts: the initial part gives out a vast overview of significant problems as well as different techniques applied to encounter modelling of rotor systems, while the latter part of the study describes the post-processing problem that occurs while performing the dynamic analysis. Findings The review incorporates the most important research works that have already placed a benchmark right from the beginning as well as the recent works that are still being carried out to further produce better outcomes. The review concludes with the modal analysis of rotor shaft to show the importance of mathematical model through its dynamic behaviour. Originality/value A critical literature review on the modelling techniques of rotor shaft systems is provided from earliest to latest along with its real-time application in different research and industrial fields.

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Alan Calderón, J., Julio C. Tafur Sotelo, Benjamín Barriga Gamarra, Jorge Alencastre, John Lozano, Rodrigo Urbizagástegui, Gonzalo Solano et Daniel Menacho. « Optimization for vibration analysis in rotating machines ». Renewable Energy and Power Quality Journal 20 (septembre 2022) : 369–73. http://dx.doi.org/10.24084/repqj20.315.

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A not stable mechanical movement transmission between systems produces equilibrium losses, such as a rotor of motors that are coupled in rotating machines. This can be studied as a disturbance “vibration” either as characteristic of the movement transmission due to controlled displacement over rotors, which transmits the movement. Therefore, in this research is presented an analysis for an optimal control of the rotor axis displacement that includes “vibration” as the part of the movement transmission. It implies mathematical modelling and specific sensors selections to correlate the vibration in this control task. Furthermore, in order to verify the proposed analysis, it was simulated and tested in a hybrid magnetic bearing system.

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Kawase, Motoyuki, et Aldo Rona. « Effect of a Recirculating Type Casing Treatment on a Highly Loaded Axial Compressor Rotor ». International Journal of Turbomachinery, Propulsion and Power 4, n^o 1 (25 mars 2019) : 5. http://dx.doi.org/10.3390/ijtpp4010005.

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The tip leakage flow over the blades of an axial compressor rotor adversely affects the axial rotor efficiency and can determine the onset of tip leakage stall. The performance of a new casing treatment concept in the shape of an axisymmetric recirculation channel is explored by steady Reynolds-Averaged Navier–Stokes (RANS) realizable k-ε modelling on the NASA Rotor 37 test case. The modelling exposed a number of attractive features. The casing treatment increased the stall margin at no penalty to the rotor isentropic efficiency over the rotor operating line. A recirculation in the casing channel self-activated and self-adjusted with the rotor loading to provide more passive flow control at higher rotor loading conditions. The nozzle-shaped recirculation channel outflow opposed the tip leakage jet, re-located the casing surface flow interface further downstream, and reduced the rotor blade tip incidence angle. This combination of features makes the new casing treatment particularly attractive for applications to high thrust-to-weight ratio engines, typical of high-performance jet aircraft.

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BAZILEVS, YURI, MING-CHEN HSU, KENJI TAKIZAWA et TAYFUN E. TEZDUYAR. « ALE-VMS AND ST-VMS METHODS FOR COMPUTER MODELING OF WIND-TURBINE ROTOR AERODYNAMICS AND FLUID–STRUCTURE INTERACTION ». Mathematical Models and Methods in Applied Sciences 22, supp02 (25 juillet 2012) : 1230002. http://dx.doi.org/10.1142/s0218202512300025.

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We provide an overview of the Arbitrary Lagrangian–Eulerian Variational Multiscale (ALE-VMS) and Space–Time Variational Multiscale (ST-VMS) methods we have developed for computer modeling of wind-turbine rotor aerodynamics and fluid–structure interaction (FSI). The related techniques described include weak enforcement of the essential boundary conditions, Kirchhoff–Love shell modeling of the rotor-blade structure, NURBS-based isogeometric analysis, and full FSI coupling. We present results from application of these methods to computer modeling of NREL 5MW and NREL Phase VI wind-turbine rotors at full scale, including comparison with experimental data.

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Li, Z., et P. Xia. « Aeroelastic modelling and stability analysis of tiltrotor aircraft in conversion flight ». Aeronautical Journal 122, n^o 1256 (12 septembre 2018) : 1606–29. http://dx.doi.org/10.1017/aer.2018.93.

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ABSTRACTIn conversion flight, the aeroelastic modelling of tiltrotor aircraft needs to consider the unsteady effect of the rotor wake bending due to the rotor tilting. In this paper, the unsteady models of the rotor wake bending and dynamic inflow have been introduced into the aeroelastic modelling of the tiltrotor aircraft in conversion flight by using Hamilton’s generalized principle. The method for solving the aeroelastic stability of tiltrotor aircraft in conversion flight has been established by using the small perturbation theory and the Floquet theory. The influences of unsteady dynamic inflow on trim control inputs and aeroelastic stability of a tiltrotor aircraft in conversion flight were calculated and analysed. The calculation results show that the required collective pitch increases with the pylon tilting forward and the unsteady inflow is trimmed primarily by the lateral cyclic pitch of the rotor. The wake bending unsteady dynamic inflow can obviously reduce the stability of the flapping modes of the rotor, and have no obvious influence on the lag modes of the rotor and the motion modes of the wing. The instability of tiltrotor occurs in the chordwise bending mode of the wing when the pylon tilts to a certain angle in high speed forward flight.

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Freakley, P. K., et S. R. Patel. « Internal Mixing : A Practical Investigation of the Flow and Temperature Profiles during a Mixing Cycle ». Rubber Chemistry and Technology 58, n^o 4 (1 septembre 1985) : 751–73. http://dx.doi.org/10.5254/1.3536091.

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Abstract From the results of mixing trials with a highly instrumented BR Banbury and biconical rotor rheometry of mixed batches, a detailed analysis of flow and mixing characteristics in the region of a rotor wing has been undertaken. An ‘angled spreader blade’ analogy of the rotor wing is proposed as being a viable basis for mathematical modelling. A one-dimensional flow analysis is used, in which power-law flow behavior and isothermal conditions are assumed. Dispersive mixing, which depends on the stress levels generated during mixing, is shown to occur throughout the entire mass of material swept in front of the rotor wing and not simply at the rotor tip. In addition, the stress levels depend more strongly on batch temperature than on rotor speed. High rotor speeds tend to lead to reduced stress levels as a result of the associated rapid rise in batch temperature, although choosing an appropriate fill factor can minimize temperature rise by promoting efficient heat transfer to the cooling water. During each rotor revolution, the rotor wing collects a mass of material from the reservoir between the rotors. This mass of material is then progressively reduced by leakage flow under the rotor tip and flow around the end of the wing, until the revolution is completed by the return of a residue to the reservoir. The flow around the end of the rotor is shown to be consistently greater than the leakage flow, although the ratio can be influenced by both fill factor and rotor speed. At high rotor speeds and low fill factors, it appears that material is retained in the regions of the side frames of the mixer and may give batch inhomogeneity through poor distribution mixing.

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Fazylova, Alina, Gani Balbayev, Diana Ilieva et Madina Aliyarova. « Analysis of rotor' critical mode of operation to be employed in the design of a wind generation control unit ». E3S Web of Conferences 180 (2020) : 02001. http://dx.doi.org/10.1051/e3sconf/202018002001.

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This paper gives an overview and comparative characteristics of the main rotors available today, with properties suitable for the climatic conditions of Almaty and Almaty region, along with their critical mode of operation. A number of studies is carried out analysing the intrinsic features and capabilities of rotors, through which the problem of choosing an optimal rotor model for the subsequent design of a wind generator control unit is solved. One of these studies is a computer simulation of the main existing rotors operating in the same climatic conditions. The selected model must fully comply with the given environmental conditions of the selected area, in which the maximum wind speed and its critical value are set for all the studied rotor models. Thanks to the comparative studies on the technical characteristics of the most commonly used rotors, as well as to the modelling results, conclusions are drawn for the most effective and optimal choice to be employed in the design of a wind generator for the climatic conditions of the Almaty region.

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Gmu¨r, T. C., et J. D. Rodrigues. « Shaft Finite Elements for Rotor Dynamics Analysis ». Journal of Vibration and Acoustics 113, n^o 4 (1 octobre 1991) : 482–93. http://dx.doi.org/10.1115/1.2930212.

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This paper presents efficient C0-compatible finite elements for the modelling of rotor-bearing systems. The proposed linearly tapered elements, which have a variable number of nodal points, are simple and attractive from a cost viewpoint. They include the effects of translational and rotatory inertia, gyroscopic moments, internal viscous and hysteretic damping, shear deformations, and mass eccentricity. Developed from the weak formulation associated with the differential equations governing the transverse dynamic behavior of rotors, these elements show a convergence pattern similar to the one obtained with conventional C1-compatible shaft elements. Numerical examples are provided, which compare the proposed approach to the C1-formulation or to previously published results.

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Castillo-Rivera, S., et M. Tomas-Rodriguez. « Helicopter modelling and study of the accelerated rotor ». Advances in Engineering Software 115 (janvier 2018) : 52–65. http://dx.doi.org/10.1016/j.advengsoft.2017.08.012.

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Tenhunen, A., et A. Arkkio. « Modelling of induction machines with skewed rotor slots ». IEE Proceedings - Electric Power Applications 148, n^o 1 (2001) : 45. http://dx.doi.org/10.1049/ip-epa:20010036.

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Kliem, W., C. Pommer et J. Stoustrup. « Stability of rotor systems : A complex modelling approach ». Zeitschrift für angewandte Mathematik und Physik 49, n^o 4 (1998) : 644. http://dx.doi.org/10.1007/s000000050113.

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Rusin, A., G. Nowak et W. Piecha. « Shrink connection modelling of the steam turbine rotor ». Engineering Failure Analysis 34 (décembre 2013) : 217–27. http://dx.doi.org/10.1016/j.engfailanal.2013.08.002.

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Jayarajan, Rekha, Nuwantha Fernando, Amin Mahmoudi et Nutkani Ullah. « Magnetic Equivalent Circuit Modelling of Synchronous Reluctance Motors ». Energies 15, n^o 12 (17 juin 2022) : 4422. http://dx.doi.org/10.3390/en15124422.

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This paper proposes a modelling technique for Synchronous Reluctance Motors (SynRMs) based on a generalized Magnetic Equivalent Circuit (MEC). The proposed model can be used in the design of any number of stator teeth, rotor poles, and rotor barrier combinations. This technique allows elimination of infeasible machine solutions during the initial machine sizing stage, resulting in a lower cohort of feasible machine solutions that can be further optimized using finite element methods. Therefore, saturation effects, however, are not considered in the modelling. This paper focuses on modelling a generic structure of the SynRM in modular form and is then extended to a full SynRM model. The proposed model can be iteratively used for any symmetrical rotor pole and stator teeth combination. The developed technique is applied to model a 4-pole, 36 slot SynRM as an example, and the implemented model is executed following a time stepping strategy. The motor characteristics such as flux distribution and torque of the developed SynRM model is compared with finite elemental analysis (FEA) simulation results.

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Morgan, Laurence, et William Leithead. « Aerodynamic modelling of a novel vertical axis wind turbine concept ». Journal of Physics : Conference Series 2257, n^o 1 (1 avril 2022) : 012001. http://dx.doi.org/10.1088/1742-6596/2257/1/012001.

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Abstract This paper introduces the X-Rotor, a hybrid vertical-horizontal axis turbine concept designed to lower the cost of energy in the floating offshore environment. The development of a double multiple streamtube (DMS) simulation tool is presented alongside a thorough discussion of the secondary correction factors included in the model. New corrections for streamline curvature effects applicable to an airfoil where the blade normal plane is not aligned with the rotor plane are derived. The DMS model is successfully validated against experimental data and against higher fidelity lifting line (LLT) simulations. Strong agreement is observed between the LLT simulations and the DMS simulations for both rotor averaged and azimuthally varying outputs, indicating that the DMS simulations can be used for future control simulations.

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Roy, Haraprasad, Abhinav Khare, Saurabh Chandraker et J. K. Dutt. « Fatigue based design and life estimation of viscoelastic rotors ». Aircraft Engineering and Aerospace Technology 90, n^o 1 (2 janvier 2018) : 96–103. http://dx.doi.org/10.1108/aeat-01-2015-0015.

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Purpose High-speed rotor subjected to cyclic stress during operation may cause fatigue failure. Thus, the design of a rotor-shaft should involve the fatigue analysis for predicting safe life. Design/methodology/approach A damped rotor shaft with a centrally mounted disc, which is simulated as steam turbine rotor, is considered for fatigue analysis. The shaft is subjected to thermal load and axial torque. It is supported by two orthotropic flexible bearings at its two extreme ends. The bearings are modelled with two-element Voigt model along each orthogonal direction to consider the elastic damped behaviour. Finite element modelling is done through Rayleigh beam theory, where each element is also considered as a Voigt model. The mathematical model involves effect of external axial torque, softening and compressive action of the shaft due to thermal load by the high temperature steam. Findings This paper attempts to find dynamic stresses in a viscoelastic rotor-shaft subject to combined bending and torsional loading and is exposed to thermal environment during operation. The dynamic stress is then used to determine fatigue and also the life of rotors. Research limitations/implications Internal damping plays an important role in deciding dynamic behaviour of rotor shaft systems. Because of this, the rotor shaft becomes unstable after a certain spin speed. Thus, the design of the rotor based on fatigue analysis is limited to the stable zone. Practical implications For this purpose, equations of whirl motion of a viscoelastic rotor-shaft are first obtained after discretizing the continuum with finite beam elements and then the time domain solution of rotor displacement is used to find the bending stress and shear stress at various locations of the rotor. Location for the maximum stress decides the failure point. Safe rotor dimensions have been predicted by comparing dynamic stresses with the Soderberg diagram. Originality/value Design of rotor for safe life operation and prediction of stability could serve a good reference for designers.

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Piłat, Adam. « Design and Analysis of Elliptic Rotor Suspended in Active Magnetic Bearing ». Solid State Phenomena 147-149 (janvier 2009) : 410–15. http://dx.doi.org/10.4028/www.scientific.net/ssp.147-149.410.

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With this paper the suspension of an elliptic rotor is considered. The operating area, electromagnetic forces and the rotor shape are analyzed along with the static and dynamic properties of the levitated rotor to obtain the required performance. The linear and non-linear stabilizing controllers are suggested to obtain stable levitation. An interdisciplinary approach for modelling and simulation tasks is proposed.

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