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Letteratura scientifica selezionata sul tema "Rotors"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 7 settembre 2024

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Articoli di riviste sul tema "Rotors"

Hou, Xukui, Ende Wang, Hui Cao, Yalong Zhu e Kai Qi. "Research on Dynamic Balance Adjustment Method of Single Braced Frame Gyroscope Rotor". MATEC Web of Conferences 256 (2019): 02005. http://dx.doi.org/10.1051/matecconf/201925602005.

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The uneven mass distribution of gyro rotors results in vibration, rotation and drift of gyro rotors, which seriously affect the performance index and life of gyro rotors. However, because there is no rigid connection between the rotary shaft and the shell of the gyro rotor, the dynamic balancing machine can only balance the vibration component of the single braced frame gyroscope rotor, and can’t measure the gyro rotor’s rotation component. By analyzing the influence of uneven rotor mass distribution on the gyro rotor performance, a method of eliminating two rotational degrees of freedom of the gimbal in gyro rotor by mandrel is proposed, which makes the dynamic balancing machine directly measure the vibration component and the moving component of the gyroscope rotor, and simplifies the dynamic balancing debugging process.

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Kay, Matthew W., Gregory P. Walcott, James D. Gladden, Sharon B. Melnick e Jack M. Rogers. "Lifetimes of epicardial rotors in panoramic optical maps of fibrillating swine ventricles". American Journal of Physiology-Heart and Circulatory Physiology 291, n. 4 (ottobre 2006): H1935—H1941. http://dx.doi.org/10.1152/ajpheart.00276.2006.

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During ventricular fibrillation (VF), electrical activation waves are fragmented, and the heart cannot contract in synchrony. It has been proposed that VF waves emanate from stable periodic sources (often called “mother rotors”). The objective of the present study was to determine if stable rotors are consistently present on the epicardial surface of hearts comparable in size to human hearts. Using new optical mapping technology, we imaged VF from nearly the entire ventricular surface of six isolated swine hearts. Using newly developed pattern analysis algorithms, we identified and tracked VF wave fronts and phase singularities (PS; the pivot point of a reentrant wave front). We introduce the notion of a compound rotor in which the rotor's central PS can change and describe an algorithm for automatically identifying such patterns. This prevents rotor lifetimes from being inappropriately abbreviated by wave front fragmentation and collision events near the PS. We found that stable epicardial rotors were not consistently present during VF: only 1 of 17 VF episodes contained a compound rotor that lasted for the entire mapped interval of 4 s. However, shorter-lived rotors were common; 12.2 (SD 3.3) compound rotors with lifetime >200 ms were visible on the epicardium at any given instant. We conclude that epicardial mother rotors do not drive VF in this experimental model; if mother rotors do exist, they are intramural or septal. This paucity of persistent rotors suggests that individual rotors will eventually terminate by themselves and therefore that the continual formation of new rotors is critical for VF maintenance.

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Prasad Rao, Jubilee, Jonathan E. Holzsager, Marco M. Maia e Javier F. Diez. "Experimental Study into Optimal Configuration and Operation of Two-Four Rotor Coaxial Systems for eVTOL Vehicles". Aerospace 9, n. 8 (17 agosto 2022): 452. http://dx.doi.org/10.3390/aerospace9080452.

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Coaxial rotors are utilized in multirotor aerial vehicles for the added thrust compared to independent rotors while keeping similar area footprints; however, performance losses should be considered. This experimental study analyzes the effects of varying motor duty cycle and propeller pitch values in motor-propeller systems with two to four coaxial rotors. The results demonstrate that in a two-rotor coaxial system, to lessen the adverse effects of a front rotor’s backwash and operate at the maximum performance, only the back motor should be operated initially up to 75% duty cycle before using the front motor up to its 75% duty cycle. Additional thrust requirements should be generated from the back rotor and then from the front rotor up to their maximum duty cycles. In two, three, and four-rotor coaxial setups, total thrust output generated is 1.6, 2.1, and 2.5 times the thrust output at system thrust performance of 86%, 76%, and 66%, respectively, of that of an isolated rotor. In a four-rotor coaxial setup, the maximum system performance is achieved when the propeller pitch values gradually increase from the first to the last rotor. The gradual increments in propeller pitch values also result in more uniform thrust sharing among rotors.

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Liu, Bao Guo, Hai Feng Hua, Long Wang Yue e Xiao Ding Xu. "Design of the Post-Processor for Rotors Dynamics Based on the STEP Standard". Advanced Materials Research 706-708 (giugno 2013): 1871–76. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.1871.

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The STEP standard is an international standard for data expressing and exchanging during the whole life cycle of the product, the neutral file is an universal data exchange form for the data exchanging. In order to develop a STEP post-processer for the rotor dynamics analysis software-Rotors Dynamics, the author elaborates the lexical analysis module and data mapping module, studies the rotor model parameter extraction based on STEP neutral file, and realizes the seamless connectivity between the Rotors Dynamics and the rotor’s CAD model.

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Andrew, Philip L. "GE Power Services Ships First F-class Extended-Life Rotors". Mechanical Engineering 138, n. 05 (1 maggio 2016): 54–55. http://dx.doi.org/10.1115/1.2016-may-4.

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This article presents an overview of technical aspects of the first F-class gas turbine life-extended rotors. Power Services, a GE Power Business, has shipped from the Greenville, S.C., facility its two F-class extended-life rotors, building upon a foundation of experience gained by executing more than 20 E-class rotor life extensions (RLEs). Experience has shown that additional features that require inspection, including rabbet fillets on wheels other than on stage one, cannot be inspected without a complete rotor disassembly. Each rotor is uniquely characterised by the combination of its particular configuration and operational history. Expanding the value of an RLE upgrade also requires that it be executed at the right point in the rotor’s life. For the two rotors evaluated to date, there have been no unexpected issues uncovered from the part inspections as compared to analytical predictions.

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Laube, Tomasz, e Janusz Piechna. "Analytical and Numerical Feasibility Analysis of a Contra-Rotary Ramjet Engine". Energies 13, n. 1 (30 dicembre 2019): 163. http://dx.doi.org/10.3390/en13010163.

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A new idea for a contra-rotary ramjet engine is presented. To define the theoretical limits of the non-typical, contra-rotary ramjet engine configuration, its analytical model was developed. The results obtained from that model and the analytical results were compared with those received from numerical simulations. The main weakness of existing rotary ramjet engine projects is the very high rotational speed of the rotor required for achieving supersonic inlet flow. In this paper, a new idea for a contra-rotary ramjet engine (CORRE) is presented and analyzed. This paper presents the results of analytical analysis and numerical simulations of a jet engine system with two rotors rotating in opposite directions. Contra-rotating rotors generate a supersonic air velocity at the inlet to the compressor at two times slower rotor’s speed. To determine the flow characteristics, combustion process, and engine efficiency of the double-rotor engine, a numerical solution of the average Navier-Stokes equations was used with the k-eps turbulence model and the non-premixed combustion model. The results of numerical simulations of flow and the combustion process inside the contra-rotary jet engine achieving a shockwave compression are shown and compared with similar data for a single-rotor engine design and analytical data. This paper presents only the calculation results of the flow processes and the combustion process, indicating the advantages of the proposed double-rotor design. The results of the numerical analysis were presented on the contours and diagrams of the pressure and flow velocity, temperature distribution, and mass fraction of the fuel.

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Pervushin, Vladimir F. "Classification of rotary cultivation tools of agricultural machines and their motion trajectories". Agricultural Engineering, n. 3 (2023): 57–64. http://dx.doi.org/10.26897/2687-1149-2023-3-57-64.

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The rotary machines and implements used for the cultivation of agricultural crops do not fully meet the agrotechnical requirements. To determine the parameters of the working tools, the authors studied the absolute trajectory of their movement and classified rotary working tools of agricultural machines according to the special location of their rotation axis, dividing them into four groups and seven subgroups: A – the first group of rotors with a horizontal-transverse axis of rotation; B – the second group of rotors with a vertical axis of rotation; C – the third group of rotors with a longitudinal axis of rotation; D, D, E and F are the fourth group of rotors with the axis of rotation located in space relative to the coordinate system XYZ at angles α, β, and γ. The article presents kinematic analysis results for rotary working tools of classes G, D, E, W having a complex location of the axis of rotation in the space. The analysis of calculating the coordinates of the motion trajectory of rotary working tools showed that for the group of rotors of class G, D, E, the motion trajectory corresponds to a compressed cycloid, and for a rotor of class G, the trajectory represents a helicoid. The obtained motion trajectories of material points of rotary working tools can be used to evaluate the process of interaction of working tools with the soil and plant material, to determine the geometric parameters of working tools, the rotor speed, and the translational speed of an agricultural machine.

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Kong, Yong-Boon, J. V. R. Prasad, Lakshmi N. Sankar e Chengjian He. "Finite State Inflow Flow Model for Coaxial Rotor Configuration". Journal of the American Helicopter Society 65, n. 3 (1 luglio 2020): 1–11. http://dx.doi.org/10.4050/jahs.65.032002.

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An analytical coaxial rotor inflow model has been developed from potential flow theory using the pressure potential superposition approach. The coaxial rotor pressure potential superposition inflow model (PPSIM) is formulated in statespace form with structure similar to the Peters–He model, except that additional off-diagonal blocks are included in the apparent mass (M-matrix) and influence coefficient matrices (L-matrix). These off-diagonal blocks take into account mutual interference effects present in a coaxial rotor system by relating the rotor's inflows due to other rotor's pressure loadings. Induced inflow distributions on both upper and lower rotors are computed using PPSIM for comparison against predictions from high-fidelity models such as GT-Hybrid and the viscous vortex particle method (VVPM). Good agreement between PPSIM-induced inflow results and GT-hybrid as well as VVPM data has been shown for hover flight condition. At low advance ratio, there are differences in fore-to-aft inflow states between PPSIM and the high-fidelity models. This is because PPSIM assumed rigid, skewed cylindrical wake geometries for both upper and lower rotors during forward flight. But in GT-Hybrid and VVPM, wake structures are allowed to move freely in space and are mainly affected by rotor-induced velocities at low advance ratios. Owing to the close proximity between upper and lower rotors, mutual interference-induced velocities significantly distorted the rotors' wake geometries. The rigid rotor wake geometry assumptions in PPSIM and the distortion captured in higher fidelity models are the reasons behind differences in rotor-induced inflows. At higher advance ratios, wake distortion effects are less prominent since free-stream inflows are significantly larger than rotorinduced velocities. Hence, smaller differences between PPSIM inflow states and those extracted from GT-Hybrid as well as VVPM are observed at high advance ratios.

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Mimmi, G., e P. Pennacchi. "Analytical model of a particular type of positive displacement blower". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 213, n. 5 (1 maggio 1999): 517–26. http://dx.doi.org/10.1243/0954406991522743.

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Many papers exist in the literature that deal with the twin-screw compressor. This usually has two different rotors, a male and a female, and is commonly used to produce compressed gas for industrial uses. However, a different type of positive displacement rotary compressor with two screws is sometimes used, one of its typical applications being in car engine supercharging. The present paper deals with the latter type, which is defined as a two-screw blower. This blower has two identical helical rotors, each with three lobes. The kinematics and the geometry of the rotors are analysed here, and a complete mathematical model for the rotor is defined. Moreover, different possible shapes of the rotors, depending on the design parameters, are analysed and the limitations in the choice of the design parameters are presented. Finally, an analysis of the theoretical specific slipping of the rotors is presented, showing which zones of the profile are the most stressed. This model will be useful for further studies on rotor pressure loads and blower dynamics.

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Qian, Kun Xi, Z. H. Xu e H. Wang. "Effects of Rotational Inertia and Bearing Force on Stability of Permanent Maglev Rotator". Applied Mechanics and Materials 150 (gennaio 2012): 50–56. http://dx.doi.org/10.4028/www.scientific.net/amm.150.50.

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The authors’ former works demonstrated that a passive magnetic (PM) rotator supported merely by PM bearings has a minimal speed, above which it can stabilize its equilibrium, under the function of a so-called Gyro-effect. It is unclear, however, by which factors is this minimal speed determined. This paper investigated the factors affecting the minimal stable speed of permanent maglev rotator, namely, the rotating inertia and PMB force. Two novel permanent maglev turbine models were designed: Model A---one stator and three rotors which have the same size but different rotational inertias; Model B---one rotor and one stator, but the stator has been devised with three different passive magnetic bearings: 1. a pair of small magnetic rings; 2. a pair of big magnetic rings; and 3. both of the two pairs of magnetic rings. Four Hall sensors distributed evenly at the turbine’s stator were used to detect the rotor’s eccentricity, and the speed sensor measured rotating speed. The calculated models of rotor’s eccentricity were established respectively for the two turbine models; the rotor’s eccentricity measuring system was built up and the rotor’s eccentricity of the two turbines was measured. The experimental data demonstrated that the rotational inertia of three rotors in the model A is 6.293×10-5 kg•m2, 1.074×10-4 kg•m2 and 2.081×10-4 kg•m2 respectively, and the corresponding minimal speed for suspension are 4597rpm, 3030rpm and 2222rpm respectively; in the model B, the magnetic force between the stator and rotor in the three cases is 92.12N, 123.48N, 212.66N respectively, corresponding to the minimal speed for suspension---3730rpm, 3120rpm and 2195rpm respectively. The results exhibited that same as the permanent maglev heart pump, permanent maglev turbines also have gyroscopic effect, which makes the rotors maintain stable suspension. And the minimal speed for suspension has a negative correlation with the rotor’s rotational inertia, namely, the bigger the inertia of the rotor, the smaller the required speed for suspension; the minimal speed for suspension also has a negative correlation with the magnetic force between the stator and rotor, that is, the larger the magnetic force, the smaller the rotating speed for suspension. Smaller minimal speed means better stability of the system, thereafter larger inertia or larger bearing force means better stability; besides, larger difference between minimal speed and performance speed of the rotator means better stability, it’s suggested permanent maglev be applied in high speed rotary machines.

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Più fonti

Tesi sul tema "Rotors"

Guirao, Victor Suman [UNESP]. "Mancais magnéticos ativos para atenuação de vibrações em eixos rotativos". Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/94526.

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Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-14Bitstream added on 2014-06-13T18:55:42Z : No. of bitstreams: 1 guirao_vs_me_ilha.pdf: 3586237 bytes, checksum: 945e594528c1e4e71d8ddb43d3bc1001 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Este trabalho trata do controle de vibrações em rotores utilizando mancais magnéticos ativos. Foram apresentadas simulações numéricas para o posicionamento ótimo de um atuador magnético utilizado para atenuar vibrações em rotor apoiado por mancais convencionais. O posicionamento ótimo do atuador foi implementado utilizando como função objetivo as normas H2 e H∞. Para modelar o rotor foi utilizado o método de elementos finitos (MEF) e a técnica de redução pseudo-modal para diminuir o esforço computacional durante o controle. As simulações mostraram que um bom posicionamento do atuador aliado ao controle LQR proporcionam grandes reduções dos níveis de vibração no rotor, quando comparado aos níveis de vibração do rotor original. Para a bancada de testes foram realizadas simulações adicionais, tendo em vista que o rotor experimental utiliza dois mancais magnéticos para levitar e controlar as vibrações. Foram apresentados os resultados de simulações de dois controladores LQR projetados com os dados da bancada de testes utilizada nos experimentos. O primeiro controlador considera modelo de rotor flexível modelado pelo método de elementos finitos e reduzido com a técnica de redução pseudo-modal. O segundo controlador foi modelado considerando o rotor como sendo um corpo rígido. Os resultados experimentais foram confrontados com os resultados de simulação e com os resultados obtidos do controlador do fabricante que forneceu a bancada
This paper deals with vibration control of rotors using active magnetic bearings. Numerical simulations were presented for the optimal positioning of a magnetic actuator used to attenuate vibrations in rotor supported by conventional bearings. The optimal positioning of the actuator was implemented using as objective function the norm H2 e H∞. To model the rotor was used finite element method (FEM) and the pseudo-modal reduction technique to reduce computational effort during the control. The simulations showed that a good positioning actuator combined to the control LQR provide great reductions in the levels of vibration in the rotor, compared the vibration of the original rotor. For the test rig were realized adittional simulations, in view of the rotor experimental uses two magnetic bearings for levitating and control the vibrations. Were present the results of two simulations designed LQR controllers with data from the test rig used in the experiments. The first controller model considers flexible rotor modeled by finite element method and reduced with the pseudo-modal reduction technique. The second controller is modeled considering the rotor as a rigid body. The experimental results were compared with simulation results and the results obtained from the controller manufacturer who supplied the test rig

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Sino, Rim. "Comportement dynamique et stabilité des rotors : application aux rotors composites". Lyon, INSA, 2007. http://theses.insa-lyon.fr/publication/2007ISAL0067/these.pdf.

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Ce travail a pour objet l'étude de la stabilité des ensembles tournants lorsque des termes d'amortissement interne (dus aux matériaux) et d'amortissement externe (paliers) sont introduits dans le modèle. La majorité des études identifiées dans la littérature sont fondées sur des développements numériques. La principale difficulté réside dans l'évaluation des paramètres physiques de l'amortissement interne qui permettent une prédiction des instabilités potentielles avec une précision suffisante. Afin de considérer des propriétés mécaniques réelles en terme d'amortissement interne, un modèle rhéologique de solide viscoélastique associé à une approche générale éléments finis de type poutre est développée, incluant les effets de cisaillement transverse. Après une description théorique (choix du modèle d'amortissement interne et équations du mouvement), une première application valide la méthode proposée. L'influence de l'amortissement sur les fréquences et les seuils d'instabilité est analysée via une étude paramétrique. Les résultats sont comparés à ceux obtenus à partir d'une approche analytique et à partir des expérimentations en rotation. Une seconde application s'intéresse à la stabilité dynamique d'un rotor composite avec prise en compte de l'amortissement avec prise en compte de l'amortissement interne et du cisaillement transverse. Une théorie simplifiée d'homogénéisation de poutre (SHBT : Simplified Homogenized Beam Theory), associée à une formulation éléments finis est introduite et utilisée pour évaluer les fréquences naturelles et les seuils d'instabilité. Cette théorie est comparée avec d'autres théories issues de la littérature (EMBT : Equivalent Modulus Beam Theory), EMBT modifié et (LBT : Layerwise Beam Theory). Une étude qualitative montre l'influence de différents paramètres (orientations, séquences d'empilement, etc. . . ) ainsi que les effets du cisaillement transverse lorsque ce dernier est introduit dans le modèle. Les effets associés sont traduits directement en terme de fréquences et de seuils d'instabilité de la structure tournante lorsque des empilements symétriques aussi bien qu'asymétriques sont considérés
This work deals with the study of dynamic instabilities within rotating assemblies due to internal damping effects. In order to consider realistic mechanical properties, in terms of internal damping, a rheological model is associated to a general finite element beam approach, including transversal shear. After a description of the theoretical background (choice of internal damping model and equations of motion), a first application illustrates the ability of the proposed model. The influence of damping on frequencies and on instability thresholds is investigated using a parametric study. Results are compared to those obtained from an analytical approach as well as from experiments. A second application is concerned with the dynamic instability of an internally damped rotating composite shaft. A Simplified Homogenized Beam Theory (SHBT), which takes into account internal damping, is introduced and then used to evaluate natural frequencies and instability thresholds. The results are compared to those obtained by using an Equivalent Modulus Beam Theory (EMBT) widely used in the literature, a Modified Equivalent Modulus Beam Theory and a Layerwise Beam Theory (LBT). The influence of laminate parameters: stacking sequences, fiber orientation and transversal shear effect on natural frequencies and instability thresholds of the shaft is studied via a parametrical study. This parametric study shows that shaft instability thresholds can be very sensitive to all these parameters

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Sino, Rim Jacquet-Richardet Georges. "Comportement dynamique et stabilité des rotors application aux rotors composites /". Villeurbanne : Doc'INSA, 2007. http://docinsa.insa-lyon.fr/these/pont.php?id=sino.

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Jarroux, Clément. "Nonlinear transient dynamics of on-board rotors supported by Active Magnetic Bearings". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI069/document.

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De manière générale, les turbomachines sont des machines tournantes permettant la conversion des différents types d’énergie. Ces dernières sont composées d’une partie mécanique en rotation, appelée rotor, interagissant avec un fluide. La rotation a donc un rôle clé pour ces machines et la liaison entre les parties fixes et les parties tournantes, appelée palier, est primordiale pour un fonctionnement fiable et optimal. Les turbomachines supportées par des paliers magnétiques actifs (PMAs) sont de plus en plus utilisées par les industriels notamment grâce à l’absence de contact direct entre parties fixes et parties tournantes, permettant un gain d’énergie et une réduction des émissions de CO2. La plupart du temps, ces machines sont « embarquées » et reposent sur des supports mobiles. Les mouvements générés par ces supports doivent être considérés dans la prévision du comportement dynamique des turbomachines afin d’améliorer les designs en conséquence. Cette thèse est une contribution à l’étude des turbomachines supportées par des PMAs sujettes à de fortes sollicitations extérieures. L’approche est numérique et expérimentale. L’utilisation d’un banc d’essais académique composé d’un système rotor-PMA, aux propriétés d’une turbomachine industrielle, a permis de tester les modèles développés pour des cas de sollicitations extérieures de type séisme et choc, générées grâce à l'excitateur 6-axes de l'equipex PHARE. Il est montré que le modèle permet la bonne prévision du comportement réel de la machine. Cet outil pourra donc être utilisé pour des designs de type industriel
Turbomachines are rotating machines enabling the conversion of the different types of energy. The latter are composed of a rotating mechanical part, called rotor, interacting with a fluid. Therefore, rotation play a key role in these machines and the mechanical link between the fixed and the rotating parts, called bearing, is essential for reliable and optimal operations. Turbomachines supported by active magnetic bearings (AMBs) are increasingly used by industrial companies, especially thanks to the absence of direct contact between fixed and rotating parts, enabling energy savings and reduction of CO2 emissions. Most of the time, these machines are "on-board" and are fixed on mobile supports. The motions generated by these supports must be considered in the prediction of the dynamic behaviour of turbomachinery in order to improve the designs accordingly. This PhD is a contribution to the study of turbomachines supported by AMBs subjected to strong external base motions. The approach is numerical and experimental. The use of an academic scale test rig comprising a rotor-AMB system, with the properties of an industrial turbomachine, allowed to test the developed models for cases of external solicitations such as earthquake and shock, thanks to the 6-axis shaker of the equipex PHARE. It is shown that the model provides good predictions of the behaviour of the machine for the tested cases. This tool can therefore be used for industrial designs

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Matos, Catherine Anne Moseley. "Download reduction on a wing-rotor configuation". Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/12058.

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Rigsby, James Michael. "Stability and control issues associated with lightly loaded rotors autorotating in high advance ratio flight". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26536.

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Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2009.
Committee Chair: J.V.R. Prasad; Committee Member: Daniel P. Schrage; Committee Member: David A. Peters; Committee Member: Dewey H. Hodges; Committee Member: Lakshmi N Sankar. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Akin, Hakki E. "A computer code for rapid calculation of bending frequencies of rotor blades". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FAkin.pdf.

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Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, June 2002.
Thesis advisor(s): E. Roberts Wood, Mark A. Couch. Includes bibliographical references (p. 195-196). Also available online.

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Atkinson, G. T. "Wind rotors in yaw". Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384765.

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Xie, Lihan. "Suivi numérique des bifurcations pour l'analyse paramétrique de la dynamique non-linéaire des rotors". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI018/document.

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Au cœur des moyens de transport, de transformation d'énergie, et de biens d'équipements, les machines tournantes peuvent avoir des comportements dynamiques complexes dus à de multiples sources de non linéarités liées aux paliers hydrodynamiques, à la présence de fissures, aux touches rotor-stator, ... Des phénomènes comme les décalages fréquentiels et donc de vitesses critiques, les cycles d'hystérésis avec sauts d'amplitudes, le changement brutal du contenu fréquentiel des réponses, sont des expressions de ces comportements. Résoudre les équations du mouvement induites par des modélisations avec des éléments finis de type poutre ou volumique, pour calculer les réponses à des sollicitations diverses (comme le balourd ou le poids propre), est réalisable avec des méthodes d'intégration pas à pas dans le temps mais au prix de temps de calcul prohibitifs. Cela devient particulièrement préjudiciable au stade du pré-dimensionnement où il est nécessaire de réaliser rapidement des études paramétriques. Aussi une alternative intéressante est de mettre en {\oe}uvre une méthode numérique, à la fois générale et efficace pour analyser la réponse non linéaire des rotors en régime stationnaire. La démarche proposée combine, dans un premier temps, la méthode de la balance harmonique (HBM) et la technique de bascule Temps-Fréquence (AFT) afin d'obtenir rapidement dans le domaine fréquentiel les réponses périodiques des rotors à grand nombre de degrés de liberté apportés par les éléments finis volumiques. Puis, l'association à la méthode de continuation par pseudo-longueur d'arc aboutit à établir continûment l'ensemble des solutions d'équilibre dynamique sur la plage de vitesse de rotation. Enfin la stabilité dynamique locale de la solution périodique est analysée grâce à des indicateurs de bifurcation basés sur l'évolution des exposants de Floquet. Ainsi sont détectées les bifurcations de branches de solutions périodiques de type point limite, point de branchement et notamment Neimark-Sacker. Leur localisation est déterminée précisément en résolvant un système augmenté constitué de l'équation du mouvement et d'une équation supplémentaire caractérisant le type de bifurcation considéré. En déclarant un paramètre du système (coefficient de frottement, jeu rotor/stator, amplitude de l'excitation,...) comme nouvelle variable, l'utilisation de la technique de continuation conjointement avec le système augmenté détermine directement le cheminement des bifurcations en fonction de ce paramètre sur la nappe des réponses non linéaires. Les suivis de bifurcations délimitent les zones de fonctionnement spécifiques, extraient efficacement l'essentiel du comportement dynamique et offrent ainsi une nouvelle approche pour dimensionner de façon efficace les systèmes notamment en rotation. Nombre des développements réalisés sont implantés dans le code de calcul Cast3M
Generally speaking, the rotating systems utilized in the energy production have a small rotor-stator gap, are able to run during long periods, and are mounted on hydrodynamic bearings. Rotor-stator interactions in case of blade loss, crack propagation due to fatigue, and a variable stiffness due to the nonlinear restoring forces of the bearings can make the rotordynamics nonlinear and the responses complicated: significant amplitude and frequency shifts are introduced, sub- and super-harmonics appear, and hysteresis occurs. It is of great importance to understand, predict and control this complicated dynamics. Due to the large number of DOFs and the broad range of study frequency, the computation time for solving the equations of motion by a temporal integration method can be quite prohibitive. It becomes particularly disadvantageous at the design stage where a parametrical study need to be quickly performed. An alternative numerical method, which is general and effective at the same time, is proposed in order to analyse the nonlinear response of the rotors at steady state. Firstly, the periodic responses of nonlinear rotors are calculated in the frequency domain by combining harmonic balance method (HBM) and alternating frequency-time (AFT). With the help of continuation method, all dynamic equilibrium solutions of nonlinear systems are determined for the range of study frequency. Then, Floquet exponents which are the eigenvalues of Jacobian are sought for stability analysis of periodic solutions. Then the local stability of the periodic solution is analysed through the bifurcation indicators which are based on the evolution of Floquet exponents. The bifurcations of periodic solution branch, such as limit point, branch point, and Neimark-Sacker bifurcation, are thus detected. By declaring a system parameter (friction coefficient, rotor / stator gap, excitation amplitude, ...) as a new variable, applying once again the continuation method to the augmented system determines directly the bifurcation's evolution as a function of this parameter. Thus, parametric analysis of the nonlinear dynamic behaviour is achieved, the stability boundary or the regime change boundary is directly determined. Numerous developments are implemented in the calculation code Cast3M

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Viana, Serra Villa Cristiano. "Dynamique non linéaire des rotors : Applications numériques et expérimentales à un rotor flexible". Ecully, Ecole centrale de Lyon, 2005. http://bibli.ec-lyon.fr/exl-doc/cvilla.pdf.

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Cette thèse s'intéresse au comportement dynamique des machines tournantes comportant des organes tels que des roulements dont le fonctionnement est décrit par des lois non linéaires. Le premier objectif de ces travaux de recherche est de mettre en oeuvre des méthodes d'analyse non linéaire afin de résoudre les équations du mouvement de tels systèmes tournants. Le second objectif consiste à effectuer des études expérimentales sur un rotor flexible et d'effectuer des corrélations avec les modèles numériques associés. La modélisation des parties linéaires du système tournante est faite par la méthode des éléments finis. Concernant les roulements, nous présentons trois modèles permettant de prendre en compte leurs non-linéarités intrinsèques telles que le jeu radial et le contact de Hertz. Nous nous intéressons alors plus particulièrement à une modélisation où la cinématique des éléments roulants est considérée. Le type de solution non-linéaire recherchée est le régime permanent
This thesis deals with the dynamic behavior of rotating machinery containing the parts whose behavior is described by non linear laws. The first goal of this research is to implement methods of non linear analysis in order to solve the equations of motion of the system. Secondly, experimental studies are made with a test rig and the results are used to update a numeric model. The rotor is represented by a finite element model. To model the bearings, three models with different levels of complexity are presented, and a model where the kinematics of the rolling elements is adopted. The type of motion of interest is the steady state vibration, and to obtain this kind of solution it is advisable to use a frequential method like the Harmonic Balance Method Alternating Frequency Time (HBM AFT). This method can be implemented with an exact condensation strategy to reduce the computational time. The HBM AFT method is validated by comparing with a direct integration of a non linear Jeffcott rotor

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Libri sul tema "Rotors"

Ralph, Jolly J., Marcolini Michael A e United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., a cura di. Helicopter main-rotor noise: Determination of source contributions using scaled model data. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Division, 1988.

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Brooks, Thomas F. Helicopter main-rotor noise: Determination of source contributions using scaled model data. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Division, 1988.

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Brooks, Thomas F. Helicopter main-rotor noise: Determination of source contributions using scaled model data. Hampton, Va: Langley Research Center, 1988.

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Bachschmid, Nicolò, Paolo Pennacchi e Ezio Tanzi. Cracked Rotors. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01485-7.

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Gilliand, Harry E. Dancing rotors. Arlington, Tex: Aerofax, 1994.

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Wilbur, Matthew L. Development of a rotor-body coupled analysis for an active mount aeroelastic rotor testbed. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1998.

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Center, Langley Research, a cura di. Development of a rotor-body coupled analysis for an active mount aeroelastic rotor testbed. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1998.

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Capitoli di libri sul tema "Rotors"

Bachschmid, Nicolò, Paolo Pennacchi e Ezio Tanzi. "Cracks in Rotating Shafts". In Cracked Rotors, 1–15. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01485-7_1.

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Bachschmid, Nicolò, Paolo Pennacchi e Ezio Tanzi. "Typical Dynamic Behaviour of Cracked Shafts". In Cracked Rotors, 17–35. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01485-7_2.

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Bachschmid, Nicolò, Paolo Pennacchi e Ezio Tanzi. "Rotor Testing for Crack Detection". In Cracked Rotors, 37–90. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01485-7_3.

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Bachschmid, Nicolò, Paolo Pennacchi e Ezio Tanzi. "Laboratory Tests on Cracked Shafts". In Cracked Rotors, 91–107. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01485-7_4.

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Bachschmid, Nicolò, Paolo Pennacchi e Ezio Tanzi. "Crack Modelling". In Cracked Rotors, 109–98. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01485-7_5.

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Bachschmid, Nicolò, Paolo Pennacchi e Ezio Tanzi. "Results Obtained Using Simulations". In Cracked Rotors, 199–246. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01485-7_6.

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Bachschmid, Nicolò, Paolo Pennacchi e Ezio Tanzi. "Some Special Effects Caused by Cracks". In Cracked Rotors, 247–301. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01485-7_7.

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Bachschmid, Nicolò, Paolo Pennacchi e Ezio Tanzi. "Crack Diagnosis in Rotating Shafts". In Cracked Rotors, 303–94. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01485-7_8.

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Dimarogonas, A., e A. Kollias. "Smart Rotors". In Rotordynamics ’92, 100–106. London: Springer London, 1992. http://dx.doi.org/10.1007/978-1-4471-1979-1_13.

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Vince, John. "Bivector Rotors". In Rotation Transforms for Computer Graphics, 181–96. London: Springer London, 2011. http://dx.doi.org/10.1007/978-0-85729-154-7_12.

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Atti di convegni sul tema "Rotors"

Kang, Hao, e Bryan Glaz. "Aeroelastic Stability Analysis of Stiff-in-plane Hingeless Rotors". In Vertical Flight Society 74th Annual Forum & Technology Display, 1–9. The Vertical Flight Society, 2018. http://dx.doi.org/10.4050/f-0074-2018-12752.

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Aeroelastic stability of stiff-in-plane hingeless rotors is investigated using the comprehensive analysis RCAS. Aeroelastic stability analysis of stiff-in-plane rotors in hover is compared to experimental measurements that shows an overall fair to good agreement for various rotor parameters. The analysis reveals that blade lead-lag damping decreases sharply and the blades become aeroelastically unstable when the blades stall. Stiff-in-plane rotor aeroelastic stability analysis in forward flight is compared to a previous numerical study. Then, using the rotor models as a baseline, a parametric study is performed for various rotor parameters including aerodynamic models, rotor speed, rotor thrust, lead-lag frequency, precone, contol system flexibility, and tip sweep. The parametric study covers lead-lag frequencies of stiff-in-plane rotors from 1.1 /rev to 1.4 /rev with a flap and a torsional frequencies of 1.15 /rev and 3.0 /rev. The parametric study shows that blade lead-lag mode of the stiff-in-plane hingeless rotors tends to become aeroelastically unstable at high advance ratios. Blade lead-lag damping of the stiff-in-plane rotors decrease as the lead-lag frequencies increase from 1.1 /rev to 1.4 /rev. Aeroelastic stability boundaries (advance ratio) increase as the rotor speed increases for a fixed rotor lift. Aeroelastic stability boundaries increase as the rotor lift decreases for a fixed rotor speed. Aerodynamic stall demonstrates significant effects on aeroelastic stability of stiff-in-plane hingeless rotors.

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Marin, Manuel A. "Rotor Dynamics of Overhung Rotors: Hysteretic Dynamic Behavior". In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68285.

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Overhung-configuration rotors are commonly used in the oil, gas and process industries. Examples of this type of equipment include power turbines, Fluid Catalytic Cracking (FCC) expanders, turbochargers and pipeline boosters. Generally, in overhung-configuration rotors, the mass concentration is near the bearing on the overhung end, so the rotor dynamics behavior of these overhung-configuration rotors is different than other equipments that have their mass concentrations between the bearing spans, such as multistage compressors. Among the more important characteristics that directly affect the rotor dynamics of the overhung rotors are gyroscopic effects on the higher modes and the fluid-film journal bearings. Gyroscopic effects are more significant in overhung configurations because of the relatively large overhung mass. These rotors also have a short bearing span and a relatively stiff shaft, so the first two modes are characterized by rigid body motion, as long as the bearing supports are rigid, as in most pipeline boosters. For pipeline boosters it would be typical to describe them as subcritical machines. If the bearing supports are not rigid, as at the disc end of power turbines and FCC expanders, then the first mode can be amplified, and it would not be unusual to describe them as supercritical machines. This paper will assume that the bearing supports are rigid, as in most pipeline boosters. A phenomenon observed in overhung rotors is known as the synchronous thermal instability or “Morton Effect”. The Morton Effect occurs when synchronous vibration produces non-uniform heating of the shaft under the bearing, leading the shaft end to develop a thermal bow. It is typical for this to happen on the overhung end of the rotor, where there is more unbalance to react with any thermal bow. The paper examines the hysteretic dynamic behavior observed in an overhung rotor mounted on tilting pad journal bearings, presenting a series of analysis using state-of-the-art rotor dynamics programs, and comparing analytical results with measurements, handling possible variables associated with synchronous “hysteresis” vibration.

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Carroll, Tim, Issi-Rae E. George e Goetz Bramesfeld. "Design Optimization of Small Rotors in Quad-Rotor Configuration". In 54th AIAA Aerospace Sciences Meeting. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2016. http://dx.doi.org/10.2514/6.2016-1788.

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Alasty, Aria, e Mohammad Malekian. "Identification of Distributed Unbalanced Mass in Flexible Rotors". In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95160.

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This paper presents a new method for identification of distributed unbalanced mass (DUM) of flexible rotors. To this end, a circular section rotor with constant area, distributed parameters, and a spatial distributed unbalanced mass is considered. Rotary inertia and gyroscopic effects are included in the dynamic of system. Then, by measuring the deflection of shaft at some points while rotating in a specific angular speed, an identification method is proposed to obtain the amount of DUM. This information can be used in balancing procedure of the rotor. The method is justified by two numerical simulations.

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Filali, Abdelkader, Lyes Khezzar e Hamza Semmari. "Improved Power for Wind Farm Savonius Rotors: Effect of Blade Shape and Rotors Position". In ASME 2020 Fluids Engineering Division Summer Meeting collocated with the ASME 2020 Heat Transfer Summer Conference and the ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/fedsm2020-20071.

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Abstract In the present study the effect of distance between five vertical Savonius rotors « Gap » on the total performance of the wind farm rotors is investigated. Numerical computations are conducted for a single Savonius turbine, and for the five clustered turbines aligned in perpendicular direction with respect to the upstream wind velocity. The study is carried out using ANSYS FLUENT commercial code and the moving mesh approach for the rotating zones is used. The turbulence model adopted in this work is the k-ω shear stress transport (SST) model. Numerical approach was first validated with previously published experimental and numerical data for a single rotating Savonius rotor case with semi-circular blades. Then, an improvement process based on the modification of the blades profiles to an elliptical shape was adopted. Subsequently, the change in distance between the five vertical Savonius rotors « Gap » has been considered with values of 0.25, 1 and 1.4 times the rotor radius (R). Results show that the Gap = 1R provides the optimum power coefficient for the wind farm rotors. However, the generated wake zone behind the five aligned rotors for this value is more important in particular for the 90 ° angle of the advanced and returned rotor blades. The field efficiency defined by the total power ratio of the five isolated rotors to the total power of the wind farm with five Savonius rotors is around 67%. All these geometrical considerations and propositions made it possible to define an optimal wind farm rotors arrangement.

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Ibrahim, Ahmed, e Ahmed M. R. Elbaz. "Investigating Efficient Clusters of Savonius Wind Turbines". In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75405.

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The wake effect is the biggest challenge when locating downwind turbines in wind farms which imposes large separation distances between turbines. In the present work, CFD simulations are presented to study possible configurations of wind farms of Savonius wind turbines. The farm is composed by in steps, starting from two-turbine configuration, adding one turbine until reaching a cluster of closely set ten rotors with an average power coefficient of 0.225. This value is very close to the single rotor’s power coefficient. The power density of the cluster is 7.55 W/m2 which is much higher than similar ten turbines located far apart to avoid wake effect. The maximum Cp of a downstream rotor in the cluster reached 0.323 which is about 40% higher than the single rotor. The adopted philosophy for placing downstream rotors is locating the rotor’s returning bucket in the low velocity region of the wake of the upstream rotor to get the least negative torque while the advancing bucket is located at the high velocity region getting higher positive torque which increases the performance. After that, two crosswind clusters are added to increase the power generated. The predicted average power coefficient for the 30 rotors farm is 0.246 which is higher than a similar isolated turbine. The increase of the Cp occurs due to the positive interactions between the clusters. The highest Cp in the farm rotors is found to be 0.411 which is higher than the single rotor’s Cp by 78%. The farm also provides a high power-density of 4.65 W/m2 which is 5 times higher than a farm with the same number of turbines located far apart.

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Miesner, Sebastian, Manuel Kessler e Ewald Kramer. "High-fidelity Simulations of Rotors in Compact Configuration". In Vertical Flight Society 78th Annual Forum & Technology Display. The Vertical Flight Society, 2022. http://dx.doi.org/10.4050/f-0078-2022-17466.

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High fidelity CFD simulations of seven rotors in compact configuration at three different flight scenarios are performed. The cases are hover, as well as 50 km/h and 100 km/h forward flight. For comparison each rotor is simulated isolated with the same RPM and pitch angle as in the configuration. Additionally, a bigger isolated rotor with the same area as the complete configuration is simulated. For the configuration as well as the bigger rotor a flight mechanic trim is performed using the flight mechanic tool VFAST. The CFD simulation is performed with FLOWer. In hover, only the center rotor showed a significant Figure of Merit (FM) drop of 16% compared to the isolated rotor. The thrust of the outer rotors is increased at the tip areas facing outwards, while the tip areas towards the center and the tip areas of the center rotor showed reduced thrust compared to the isolated rotor. The wake contraction at the outer rotors is increased compared to the bigger rotor. For the 50 km/h forward flight the efficiency of the front rotors is increased (10%-17%) and the rear ones decreased (11%-16%). In this case the wake is directly convected from the front rotors into the rear rotor planes and strong vortex interactions occur. For the 100 km/h case the efficiency gain of the front rotors is reduced to 3%-11% and the decrease to 5%-9%. Due to the higher pitch the wake of the rotors flows away from the rotor plane and the rotor-rotor interactions are reduced.

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Atte, Abraham, e Huergen Rauleder. "Investigation of Rotor Vertical Offset Effects on Quadrotor Performance". In Vertical Flight Society 80th Annual Forum & Technology Display. The Vertical Flight Society, 2024. http://dx.doi.org/10.4050/f-0080-2024-1388.

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Quadrotor performance and stereoscopic particle image velocimetry (PIV) flow field wind tunnel measurements presented in this work aim to quantify rotor-rotor interactions and their manifestations for various hub spacings, including vertical offset. Three quadrotor configurations were examined; the cross configuration and two plus configurations. In the cross configuration, the fore rotors were lowered relative to the aft rotors. In the Plus 1 configuration the fore and aft rotors were lowered, whereas in the Plus 2 configuration the side rotors were lowered. In the cross configuration, increases in hub spacing led to decreases in the thrust coefficient (CT ) of the fore rotors for the same rotational speed. An increase in the rotor vertical separation resulted in an increase in CT of the aft rotors of up to 24%. Results showed that large vertical rotor separation and close hub spacings yielded best performance. The side rotors in the Plus 1 and Plus 2 configurations showed differing thrust coefficients based on relative rotor position and wind speed leading to aerodynamic asymmetries. In the Plus 1 configuration, the aft rotor experienced significant changes in performance based on both the hub and vertical spacings as it moved into the beneficial upwash regions from the side rotors, as evidenced by PIV flow field measurements. Performance results of the Plus 2 configuration showed positive effects of the fore rotor on the side rotors as they were lowered, exacerbating aerodynamic asymmetries. The aft rotor also experienced beneficial effects from the side rotors, which diminished as the side rotors were lowered. These results were further confirmed by measured rotor inflow velocities from the PIV. An examination of the thrust-to-torque ratios of the plus configurations indicated best performance for a rotor vertical separation of 0.5R.

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Dayhoum, Abdallah, Alejandro Ramirez-Serrano e Robert Martinuzzi. "Aerodynamic Optimization and Experimental Analysis of Shrouded Rotor Blades". In Vertical Flight Society 80th Annual Forum & Technology Display. The Vertical Flight Society, 2024. http://dx.doi.org/10.4050/f-0080-2024-1289.

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Unmanned Aerial Vehicles (UAVs), particularly Vertical Take-Off and Landing (VTOL) aircraft such as quad-rotors and helicopters, have gained attention for diverse applications in military and civilian domains. However, to increase applications, reducing their power consumption and their restricted payload capacity. This paper describes a method to enhance the thrust capabilities of typical shrouded rotors through a novel rotor design. Beginning with an airfoil with a high lift-to-drag ratio. Blade element momentum theory (BEMT) is used to optimize the rotor's chord and twist distributions systematically along with precise induced velocity prediction in shrouded rotors. Furthermore, a validation process requires rotor manufacturing and experimentation. BEMT harmonizes momentum and blade element theories, offering a comprehensive framework for rotor behavior modeling, especially in hovering conditions. First, second, and third degrees functions are used to express both the chord and twist distributions along the rotor radius from where the best rotor design is obtained, for this, an experimental validation is employed. The experimental tests demonstrate improved performance, especially when the rotor designed using the higher degree functions is employed. The proposed approach provides a comprehensive approach to shrouded rotor design, offering advancements.

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Baz, Ahmed M., Nabil A. Mahmoud, Ashraf M. Hamed e Khaled M. Youssef. "Optimization of Two and Three Rotor Savonius Wind Turbine". In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43988.

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The present work investigates the performance of Savonius wind turbine using two or three rotors. The new turbine design was found to have higher power coefficient compared with single rotor design. The peak average power coefficient of the three rotors was computed to be 50% higher than that of the single rotor design. The torque coefficient was also higher than that of the single rotor turbine at high tip speed ratio. This improved performance is attributed to the favorable aerodynamic interaction between the rotors which accelerates the flow around the rotors and generates higher turning torque in the direction of rotation for each rotor. The optimized arrangement of rotors showed that the upstream rotor and one downstream rotor should have a similar direction of rotation while the second downstream rotor is rotating in opposite direction.

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Rapporti di organizzazioni sul tema "Rotors"

Zheng, Wanzheng, e Jason Merret. Aerodynamic Survey of Novel eVTOL Configuration Using SU2. Illinois Center for Transportation, agosto 2022. http://dx.doi.org/10.36501/0197-9191/22-014.

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This report summarizes computational fluid dynamics (CFD) results of electric vertical takeoff and landing (eVTOL) geometries using the SU2 Reynolds-averaged Navier-Stokes (RANS) solver. Geometries were generated based on the Smart Transportation Infrastructure Initiative (STII) Rappor 15th iteration with various rotor-installment solutions. It was found that although open rotors installed on an underwing pylon were superior to shrouded rotors installed in a canoe, the canoe configuration would provide more potential for improvement, and using a canoe door to cover the first rotor opening would reduce the drag experienced by the canoe case below that upon the rod case. Rotor doors were found to be most efficient in reducing drag of the canoe case: Average drag reduction with covering the first rotor and all rotors was 66 and 165 counts, respectively. Changing rotor distributions along the chordwise direction had minimal impact on drag reduction, and placing rotors along the spanwise direction was not advised due to the increase of the projected frontal area. Increasing canoe chord length did not have significant impact on drag reduction; and if rotor doors were implemented, increasing canoe size had negative impact on drag. Rounding rotor edges did not change the aerodynamic performance of the canoe case but promotes vertical air intake when running lifting fans. Drag received by the canoe parabolically correlated to rotor diameter, with 126 counts of drag if the rotor diameter was 0 and 377 counts if the rotor diameter was 2.95 ft. Fuselage and tail added an average 179 counts of drag, and thus the aforementioned differences were still significant in the scale of aerodynamic properties of the full configuration.

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Smith, A. B. Fast neutrons incident on rotors : - tantalum. Office of Scientific and Technical Information (OSTI), marzo 2005. http://dx.doi.org/10.2172/861625.

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Romero, Louis Anthony. Spin stabilized magnetic levitation of horizontal rotors. Office of Scientific and Technical Information (OSTI), ottobre 2004. http://dx.doi.org/10.2172/882322.

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Bortolotti, Pietro, Emmanuel Branlard, Anurag Gupta, Nick Johnson, Jason Jonkman, Patrick Moriarty, Joshua Paquette, Dave Snowberg e Paul Veers. The Wind Turbine Rotors of the Future: A Research Agenda from the Big Adaptive Rotor Project. Office of Scientific and Technical Information (OSTI), maggio 2024. http://dx.doi.org/10.2172/2356775.

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Maniaci, David Charles, Christopher Lee Kelley e Phillip Chiu. Assessment of Scaled Rotors for Wind Tunnel Experiments. Office of Scientific and Technical Information (OSTI), luglio 2015. http://dx.doi.org/10.2172/1235645.

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Morino, Luigi, Slobodan Sipcic e Mark Downey. Unsteady Free-Wake Viscous Aerodynamic Analysis of Helicopter Rotors. Fort Belvoir, VA: Defense Technical Information Center, novembre 1989. http://dx.doi.org/10.21236/ada217166.

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Loth, Eric. 50 MW SEGMENTED ULTRALIGHT MORPHING ROTORS FOR WIND ENERGY. Office of Scientific and Technical Information (OSTI), giugno 2024. http://dx.doi.org/10.2172/2375003.

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Cheney, M. C., T. Olsen, G. Quandt e P. Archidiacono. Analysis and Tests of Pultruded Blades for Wind Turbine Rotors. Office of Scientific and Technical Information (OSTI), luglio 1999. http://dx.doi.org/10.2172/12142.

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Blau, Peter Julian. Prospects for Titanium-Based Materials as Truck Disc Brake Rotors. Office of Scientific and Technical Information (OSTI), settembre 2010. http://dx.doi.org/10.2172/1081592.

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Shiu, Henry, e Cornelis P. van Dam. Active Flow Control on Bidirectional Rotors for Tidal MHK Applications. Office of Scientific and Technical Information (OSTI), agosto 2013. http://dx.doi.org/10.2172/1090896.

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