Дисертації: "Rotor Modelling"

1

ANNA, RICARDO E. SILVA DE SANT. "ROTOR ACCIDENT ANALYSIS: MODELLING AND SIMULATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11885@1.

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A Dissertação aqui apresentada descreve um acidente em um rotor de máquina de grande porte (compressor de ar) de uma fábrica de fertilizante cujas conseqüências foram perdas financeiras de alta monta tanto para a empresa quanto para o Estado, pela importância econômica onde a fábrica é situada. O objetivo da Dissertação foi simular matematicamente o acidente ocorrido e esclarecer o mesmo. Para se chegar ao diagnóstico do problema se modelou o rotor e o discretizou pelo Método de Elementos Finitos. As técnicas de investigação do problema e a sua seqüência de investigação podem ser tomadas como base em investigação de eventuais acidentes envolvendo rotores futuramente. O capítulo relativo a Análise Modal será extraído como base de apostila para curso envolvendo pessoal da área de Manutenção Mecânica.
A problem related with an air compressor gave birth to the MSc Thesis. Problems related with rotative machines are usual in the industrial field. Difficulties come from the data gathering in order to analyze, and propose a theory of failure in order to explain and avoid the recurrence of such problem. Modelling a rotor with a Timoshenko beam element and the discretization by finite element method permit the dynamical analysis and the modal analysis of the rotor considering its interaction with the radial and thrust bearings (assuming stiffness and rigidity). The work is divided in seven chapters: chapter one introduces the work and gives the overview of it; chapter two describes the industrial problem; chapter three is a brief explanation of bearing types and the fundamental principle of lubrication; chapter four introduces vibration theory and modal analysis; chapter five introduces the finite element method; chapter six is the simulation of the problem, using tailor-made MATLABr programs to reconstruct the problem and to compare the test field results with the here mentioned formulation; chapter seven discusses the results and proposes future works. Appendix shows the kinetic theory and the beam deformation model used in the program and the Laval simple rotor as a limited description of the dynamic of a rotor with distributed mass, rigidity and stiffness. The aim of this work is to help understand and avoid the recurrence of the failure described and to easy the understanding of modal analysis for new engineers and technicians which will deal with rotor dynamics.

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2

Bréus, Elsa. "Finite elements modelling of rotor flapping mass." Thesis, KTH, Lättkonstruktioner, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-224154.

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In the frame of increasing flight safety, finite element models are developed to computethe stresses in critical parts. The results obtained often complete the ones derived from fullscale experimental tests and analytical estimations. A finite element model is particularlyuseful to simulate many different flight configurations that can not be tested experimentally.This paper presents the different stages in the development of a finite element model ofa rotor flapping mass. On a helicopter the flapping mass makes the connection betweenblades and rotor hub. This study particularly focuses on the estimation of the fatiguelimit of a composite component. This component, called roving winding, is particularlycritical as it sustains most of the loads applied on the flapping mass. Getting an accuraterepresentation of the stress distribution in the roving was the main objective. The resultsderived from the model presented here were compared to experimental ones to ensure itsaccuracy. The confidence in the model obtained makes possible its use to evaluate theimpact of some material change or geometry modifications. The model also permitted toevaluate the impact of some productions defects on a composite part.

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3

Sadri, Malek Arsalan. "Numerical modelling of rotor/stator interactions in turbomachinery." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/7828.

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4

Mear-Stone, Leah Isobel. "Theoretical modelling of flow in rotor-stator systems." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.681054.

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The prevention of hot gas ingress between rotating and stationary discs in gas turbines is big business, with experimental and computational research being common in the sector. Experimental rigs, operating at a fraction of the engine size and in simulated fluid dynamic conditions, model the engine environment. Computational Fluid Dynamics (CFD) is used in both academia and industry to model the flow and heat transfer in a turbine. CFD is expensive, time consuming and requires detailed experimental validation. The engine designer has a need for simpler, faster mathematical modelling methods, ultimately to be used in 1D design codes. The research in this thesis stems from this need for the industrial engine designers to be able to predict the flow, pressure and temperatures in the secondary-air-system. Momentum-integral equations are known to model flow over rotating and stationary discs in isolation. This thesis shows that the momentum-integral equations can be solved together, to successfully model the flow inside a rotor and stator cavity. New momentum-integral equations are derived, free of the incorrect assumption that swirl ratio inside a rotor-stator cavity does not vary with radius. Two cavity models are described based upon the momentum-integral equations: one for a closed cavity and one for a cavity with sealing flow and no ingress. Both are computationally fast and are shown to give good agreement with experimental measurements and CFD results. Detailed flow structures are given for a range of rotor-stator cavity cases and the results of the models allow conclusions about the flow structure to be drawn. It is found that the outer region, where flow leaves the rotor and is entrained by the stator, is not affected by sealing flow. As well as complete cavity models, two other models for specific rotor-stator phenomenon have been derived. The effect of ingress on the swirl ratio in the cavity has been modelled, using a momentum balance approach. The buffer ratio and buffering effect, which quantify how the rotor is protected from ingress, have been defined, modelled and validated against measurements of adiabatic effectiveness for four different seal geometries. The model has allowed the calculation of Φ′min,r, the sealing flow rate where the effectiveness on the rotor reaches 95%.

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5

Gustavsson, Rolf. "Rotor dynamical modelling and analysis of hydropower units /." Luleå: Division of Computer Aided Design, Department of Applied Physics and Mechanical Engineering, Luleå University of Technology, 2008. http://epubl.ltu.se/1402-1544/2008/50/.

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6

Karlsson, Martin. "Electro-mechanical modelling and analysis of hydroelectric rotor systems." Licentiate thesis, Luleå : Luleå University of Technology, 2006. http://epubl.luth.se/1402-1757/2006/10.

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7

McDarby, John Michael. "Modelling of turbulent rotor-blade flow and ground effect." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1444821/.

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Rotor blade flows occur in numerous physical systems from helicopters to fans, and from propellers to food mixers. Many previous studies have concentrated on the laminar flow generated by a set of rotors but in many practical cases the flow is turbulent, a setting in which previous research appears to be mainly experimental or purely numerical. The thesis examines turbulent rotor flow as its prime feature, before moving on to the impact of the ground and side structures on the flow. Whilst there exists a wide variety of rotor blade flows in industry, the present research is motivated by the application to helicopters. Using asymptotic analysis and computational methods the thesis first examines the turbulent boundary layer on a flat plate with a moving surface and, second, a rotating disc. Analytical and numerical predictions are then derived and compared with previous results. Asymmetry about the axis of rotation is introduced next and the problem of a rotating cut-disc is studied as an approximation to a set of rotors. A numerical solution is obtained and is supported by analytical results. Blade inclination and thickness are then incorporated into the three-dimensional case, with asymmetric blade shape being analyzed as if in two dimensions only. The influence of ground effect is examined firstly through the use of an image potential in the two-dimensional asymmetric blade shape problem and secondly in the axisymmetric case of flow between a stationary and a rotating disc. A numerical solution is determined and compared with existing research, whilst an analytical solution is produced for large radii. The flow between a stationary disc and a rotating cut disc is then briefly discussed before, finally, the possible extension of this thesis to the problem of turbulent jets is examined.

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8

Abdulqadir, Sherwan Ahmed. "Turbulence modelling for horizontal axis wind turbine rotor blades." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/turbulence-modeling-for-horizontal-axis-wind-turbine-rotor-blades(2536b213-3a0c-4977-ac39-916a9fce98d2).html.

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This Thesis aims to assess the reliability of turbulence models in predicting the flow fields around the horizontal axis wind turbine (HAWT) rotor blades and also to improve our understanding of the aerodynamics of the flow field around the blades. The simulations are validated against data from the NREL/NASA Phase VI wind turbine experiments. The simulations encompass the use of fourteen turbulence models including low-and high-Reynolds-number, linear and non-linear eddy-viscosity models and Reynolds stress models. The numerical procedure is based on the finite-volume discretization of the 3D unsteady Reynolds-Averaged Navier-Stokes equations in an inertial reference frame with the sliding mesh technique to follow the motion of the rotor blades. Comparisons of power coefficient, normalised thrust, local surface pressure coefficients (CP) and the radial variation of the section average of normal force coefficients with published experimental data over a range of tip-speed ratios, lead to the identification of the turbulence models that can reliably reproduce the values of the key performance indicators. The main contributions of this study are in establishing which RANS models can produce quantitatively reliable simulations of wind turbine flows and in presenting the flow evolution over a range of operating conditions. At low (relative to the blade tip speed) wind speeds the flow over the blade surfaces remains attached and all RANS models return the correct values of key performance coefficients. At higher wind speeds there is circumferential flow separation over the downwind surface of the blade, which eventually spreads over the entire surface, Moreover, within the separation bubble the centrifugal force pumps the flow outwards, which at the higher wind speeds suppresses the formation of the classical tip vortices. More refined RANS models which do not rely on the linear effective viscosity approximation generally lead to more reliable predictions over this range of higher wind speeds. In particular the Gibson-Launder version of the Reynolds stress transport model and the high-Re versions of the Lien et al non-linear k-ε produce consistently reliable simulations over the entire range of wind speeds. By contrast some popular linear effective viscosity models, like the SST (k-ω) and the v^2-f, perform the poorest over this complex flow range. Finally all RANS models are also able to predict the dominant (lowest) frequency of the pressure fluctuations and the non-linear effective viscosity models, the Launder and Shima version of RSM and the SST are also able to return some of the higher frequencies measured.

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9

Sarvat, Mushtaq Ahmad B. "Modelling and control of a twin rotor MIMO system." Thesis, University of Sheffield, 2001. http://etheses.whiterose.ac.uk/14820/.

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In this research, a laboratory platform which has 2 degrees of freedom (DOF), the Twin Rotor MIMO System (TRMS), is investigated. Although, the TRMS does not fly, it has a striking similarity with a helicopter, such as system nonlinearities and cross-coupled modes. Therefore, the TRMS can be perceived as an unconventional and complex "air vehicle" that poses formidable challenges in modelling, control design and analysis and implementation. These issues are the subject of this work. The linear models for 1 and 2 DOFs are obtained via system identification techniques. Such a black-box modelling approach yields input-output models with neither a priori defined model structure nor specific parameter settings reflecting any physical attributes. Further, a nonlinear model using Radial Basis Function networks is obtained. Such a high fidelity nonlinear model is often required for nonlinear system simulation studies and is commonly employed in the aerospace industry. Modelling exercises were conducted that included rigid as well as flexible modes of the system. The approach presented here is shown to be suitable for modelling complex new generation air vehicles. Modelling of the TRMS revealed the presence of resonant system modes which are responsible for inducing unwanted vibrations. In this research, open-loop, closed-loop and combined open and closed-loop control strategies are investigated to address this problem. Initially, open-loop control techniques based on "input shaping control" are employed. Digital filters are then developed to shape the command signals such that the resonance modes are not overly excited. The effectiveness of this concept is then demonstrated on the TRMS rig for both 1 and 2 DOF motion, with a significant reduction in vibration. The linear model for the 1 DOF (SISO) TRMS was found to have the non-minimum phase characteristics and have 4 states with only pitch angle output. This behaviour imposes certain limitations on the type of control topologies one can ado·pt. The LQG approach, which has an elegant structure with an embedded Kalman filter to estimate the unmeasured states, is adopted in this study. The identified linear model is employed in the design of a feedback LQG compensator for the TRMS with 1 DOF. This is shown to have good tracking capability but requires. high control effort and has inadequate authority over residual vibration of the system. These problems are resolved by further augmenting the system with a command path prefilter. The combined feedforward and feedback compensator satisfies the performance objectives and obeys the constraint on the actuator. Finally, 1 DOF controller is implemented on the laboratory platform.

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10

Karlsson, Martin. "Modelling and analysis of multiphysical interactions in hydropower rotor systems /." Luleå : Polhem Laboratory, Division of Computer Aided Design, Department of Applied Physics and Mechanical Engineering, Luleå University of Technology, 2008. http://epubl.ltu.se/1402-1544/2008/27/.

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11

Ruge, Montilla Jhonn Hamberth. "Modelling of tilt rotor mission performance to assess environmental impact." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7292.

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New technologies and new rotorcraft operations are being developed in order to meet new environmental requirements such as noise reduction and less pollutant emissions. In this project a parametric study was developed over a tilt rotor model in order to assess the environmental impact in terms of operational parameter and fuel burned looking at pollutant emission released into the air such as NOx, CO, UHC, PM, CO2 & H2O In order to perform the study previously stated, a computational tool build on Simulink titled tilt rotor mission performance was developed to run a single mission profile as a base line making different operational variations on every mission segment looking at deviations over fuel burned and pollutant emissions. The contribution of pollutant emissions during the cruise segment was compared to other phases obtaining 80% of CO2 and H2O, 75% of CO and UHC, 77% of NOx, and 78% of PM. Also, comparing the distance flown of the tilt rotor with some turboprop aircraft, it was found that the fuel burned and levels of CO2 are higher using tilt rotor rather than turboprop aircraft. On the other hand this is much better than helicopters.

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12

Materano, Blanco Gilberto Ignacio. "Numerical modelling of pressure rise combustion for reducing emissions of future civil aircraft." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9259.

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This work assesses the feasibility of designing and implementing the wave rotor (WR), the pulse detonation engine (PDE) and the internal combustion wave rotor (ICWR) as part of novel Brayton cycles able to reduce emissions of future aircraft. The design and evaluation processes are performed using the simplified analytical solution of the devices as well as 1D-CFD models. A code based on the finite volume method is built to predict the position and dimensions of the slots for the WR and ICWR. The mass and momentum equations are coupled through a modified SIMPLE algorithm to model compressible flow. The code includes a novel tracking technique to ensure the global mass balance. A code based on the method of characteristics is built to predict the profiles of temperature, pressure and velocity at the discharge of the PDE and the effect of the PDEs array when it operates as combustion chamber of gas turbines. The detonation is modelled by using the NASA-CEA code as a subroutine whilst the method of characteristics incorporates a model to capture the throttling and non-throttling conditions obtained at the PDE's open end during the transient process. A medium-sized engine for business jets is selected to perform the evaluation that includes parameters such as specific thrust, specific fuel consumption and efficiency of energy conversion. The ICWR offers the best performance followed by the PDE; both options operate with a low specific fuel consumption and higher specific thrust. The detonation in an ICWR does not require an external source of energy, but the PDE array designed is simple. The WR produced an increase in the turbine performance, but not as high as the other two devices. These results enable the statement that a pressure rise combustion process behaves better than pressure exchangers for this size of gas turbine. Further attention must be given to the NOx emission, since the detonation process is able to cause temperatures above 2000 K while dilution air could be an important source of oxygen.

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13

Flack, Timothy John. "Induction motor modelling using finite elements." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/7405.

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14

McCallum, Duncan C. (Duncan Craig). "Dynamic modelling and control of a magnetic bearing-suspended rotor system." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14554.

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15

Nowicki, Nathalie. "MEASUREMENT AND MODELLING OF MULTICOPTER UAS ROTOR BLADE DEFLECTION IN HOVER." Thesis, KTH, Lättkonstruktioner, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-200713.

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Package deliveries, surveillance and entertainment are all areas where unmanned aerial systems, (UAS), face a growing market. Multicopters, being one of the most popular UAS, can both be bought and built rather easily due to the fairly simple design and low cost. However, lack of regulations and absence of research of structural properties of the rotor blades motivates the purpose of this project, as better knowledge results in safer products with an increased operational envelope. The out of plane deflection and the change in pitch of two commercially available multicopter UAS rotor blades, one plastic and one carbon fiber reinforced, have thus been studied for an isolated rotor in hover mode. The deformation was measured using both a Digital Single-Lens Reflex (DSLR) camera and tailored photogrammetry with two cameras for a rotation speed range. The results were compared to analytical expressions of coning angle from helicopter theory and to one model that was developed for a finite element simulation was evaluated. The conclusion is that for the plastic blades the out of plane deflection is negative quadratic to linear relation to the rotation speed while the pitch has a trend of decreasing angle. For the carbon fiber blades the relation is more linear to quadratic for the deflection while the pitch is almost constant.
Obemannade luftfarkoster (UAS) har på senare år fått en allt större marknad tack vare ny teknik och nya användningsområden så som bevakning, leveranser och nöje. Multikoptrar är den vanligast förekommande typen av UAS och deras framfart motiveras oftast av de relativt låga inköpspriserna samt den enkla designen som underlättar för egna konstruktioner. Tyvärr saknas forskning inom flera områden relaterade till produkten, däribland de strukturella egenskaperna hos rotorbladen, och regleringen är heller inte enhetlig. Dessa sakfrågor har därför givit en grund till behovet av detta projekt med förhoppningen att det i framtiden kan byggas säkrare produkter med bättre prestanda. I projektet har således utböjningen och vridningen av två kommersiellt tillgängliga multikopter rotorblad undersökts, ena helt gjort av plast medan den andra av kolfiberförstärkt plast. Detta gjordes för en isolerad rotor i hovring-läge. Utböjningen från rotorplanet mättes för ett spann av rotationshastigheter både med hjälp av systemkamera och med specialanpassad fotogrammetri. Resultaten jämfördes med analytiska uttryck från helikopterteori samt försöktes återskapades i en modell i finit element simuleringar. Slutsatsen som kan dras är att sambandet mellan utböjning med avseende på rotorhastigheten är, för bladen tillverkade av ren plast är negativt kvadratiskt till linjär, medan det för kompositbladen är mer linjärt till positivt kvadratiskt. Pitch vinkeln har påvisar en avtagande trend for plast bladen och nästintill konstant vinkel för komposit bladen.

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16

Abulrub, Abdul-Hadi G. "Modelling and control of contact in magnetic bearing/flexible rotor systems." Thesis, University of Bath, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437436.

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17

Yucekayali, Arda. "Development Of A Comprehensive And Modular Modelling, Analysis And Simulation Tool For Helicopters." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613643/index.pdf.

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Helicopter flight dynamic, rotor aerodynamic and dynamic analyses activities have been a great dispute since the first helicopters, at both design and test stages. Predicting rotor aerodynamic and dynamic characteristics, helicopter dynamic behavior and trimmed flight conditions is a huge challenge to engineers as it involves the tradeoff between accuracy, fidelity, complexity and computational cost. Flight dynamic activities such as
predicting trim conditions, helicopter dynamic behavior and simulation of a flight condition or maneuver mostly require analysis tools with low computational cost and complexity. However this decreases accuracy and fidelity of the model. On the other hand, analyses at design stages, such as
blade geometric and structural design mostly requires accurate and higher fidelity aerodynamic load predictions over the rotor disk. Contrarily this brings high computational cost and complexity. Therefore separate analysis tools for each objective or one complete tool that can be used for all purposes are essential. Throughout this study a helicopter mathematical including trim model with a selective and modular structure is developed as a generic analysis tool. The selective structure enables the mathematical model to be used in both flight dynamic and comprehensive analysis while the modular structure plays a role as an infrastructure for further developments. The mathematical model developed is validated with flight test data of several helicopters. Besides, commercial helicopter comprehensive analysis tools are used to validate the mathematical model analyses. Results showed good agreement with the compared data.

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18

Ilie, Katherine-Rodica, and Katherine ilie@rmit edu au. "Modelling, Simulation and Optimisation of Asymmetric Rotor Profiles in Twin-screw Superchargers." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080213.144857.

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There is a growing recognition worldwide of the need for more powerful, smaller petrol engines, capable of delivering the higher picking power of larger engines, yet still being economical and environmentally friendly when used for day-to-day driving. An engineering solution for more efficient engines has been considered by research so far. It has been identified that superchargers can potentially improve the performance of automotive engines; therefore research has focused on developing superchargers and supercharger components with higher efficiency. Of particular interest to the research presented in this thesis has been the twin-screw supercharging compressor with design adapted for automotive use (the twin-screw supercharger). The performance of this supercharger type depends on the volume and total losses of the air flow through the supercharger rotors more than on any other aspects of its behaviour. To accurately predict the efficiency of the twin-screw su percharger for matching a particular engine system, accurate supercharger design is required. The main objective of this research was the investigation of the existing limitations of twin-screw superchargers, in particular leakage and reduced efficiency, leading to the development of optimal asymmetric rotor profiles. This research has been completed in four stages defining an innovative rotor design method. The parametric three-dimensional geometric model of twin-screw supercharger rotors of any aspect ratio was developed. For model validation through visualisation, 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 and performance optimisation. Through the application of this new rotor design method, new opportunities are created for the twin-screw supercharger design practice, making it a part of the engineering solution for more efficient engines.

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19

Pretorius, Morné. "Comprehensive active magnetic bearing modelling taking rotor dynamics into account / M. Pretorius." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2647.

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The McTronX Research Group at the North-West University is conducting research in the field of Active Magnetic Bearings (AMBs) with the aim of establishing a knowledge base for future industry consultation. AMBs are environmentally friendly and are a necessity in the pebble bed modular reactor (PBMR), a South-African initiated project, which is predicted to be the means of supplying Africa and many other countries with modular energy in the future. Aside from the PBMR, there are numerous other AMB industrial applications. The aim of this project is to develop a comprehensive AMB model that considers the effect that rotor dynamics has on an AMB system. This model is used to analyse a double radial AMB, capable of suspending a rigid- and flexible rotor, to explain previously noticed phenomena. Two modelling methods are focussed on namely the System Matrix Method and Transfer Matrix Method (TMM) both of which are implemented in MATLAB®. The rigid rotor model is firstly implemented as a point mass in state-space form followed by use of the TMM to analyse its bending modes. The stability and critical speeds of the system are analysed due to a change in the supports' properties along with rotor gyroscopy and its effect on the system. During analysis of the flexible rotor the TMM was used via a similar approach as was followed with the rigid rotor. The results indicate that the system is experiencing lower than expected damping due to the model that is used within the control loop. The previously assumed rotor model in the control loop is not sufficient to describe its complex behaviour. This causes the unexpected damping characteristics. This project suggests future work to be conducted in expanding the frequency domain model of the rotor within the control loop to account for its physical shape.
Thesis (M.Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2009.

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20

Suttie, David R. "Analysis and indicial modelling of helicopter tail rotor orthogonal blade vortex interaction." Thesis, University of Glasgow, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433176.

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21

Giannakakis, Panagiotis. "Design space exploration and performance modelling of advanced turbofan and open-rotor engines." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/7957.

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This work focuses on the current civil engine design practice of increasing overall pressure ratio, turbine entry temperature and bypass ratio, and on the technologies required in order to sustain it. In this context, this thesis contributes towards clarifying the following gray aspects of future civil engine development: the connection between an aircraft application, the engine thermodynamic cycle and the advanced technologies of variable area fan nozzle and fan drive gearbox. the connection between the engine thermodynamic cycle and the fuel consumption penalties of extracting bleed or power in order to satisfy the aircraft needs. the scaling of propeller maps in order to enable extensive open-rotor studies similar to the ones carried out for turbofan engines. The rst two objectives are tackled by implementing a preliminary design framework, which comprises models that calculate the engine uninstalled performance, dimensions, weight, drag and installed performance. The framework produces designs that are in good agreement with current and near future civil engines. The need for a variable area fan nozzle is related to the fan surge margin at take-o , while the transition to a geared architecture is identi ed by tracking the variation of the low pressure turbine number of stages. The results show that the above enabling technologies will be prioritised for long range engines, due to their higher overall pressure ratio, higher bypass ratio and lower speci c thrust. The analysis also shows that future lower speci c thrust engines will su er from higher secondary power extraction penalties. A propeller modelling and optimisation method is created in order to accomplish the open-rotor aspect of this work. The propeller model follows the lifting-line approach and is found to perform well against experimental data available for the SR3 prop-fan. The model is used in order to predict the performance of propellers with the same distribution of airfoils and sweep, but with di erent design point power coe cient and advance ratio. The results demonstrate that all the investigated propellers can be modelled by a common map, which separately determines the ideal and viscous losses.

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22

Bonello, Philip. "The non-linear modelling of squeeze film damped rotor-dynamic systems : an efficient integrated approach." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268939.

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23

Ehtemam, Haghighi Vahid. "Modelling, Simulation and Experimental Diagnostics of Failures in Rotor Systems Supported by Active Magnetic Bearings." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/75982.

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In this thesis, a comprehensive approach for troubleshooting and diagnostics of rotors supported with Active Magnetic Bearings is demonstrated. For this purpose, a SKF MBRotor-II Test Stand supported by an industrial controller and its software package, is modelled and simulated to provide full understanding of the test rig. Finally, various mechanical and controller faults were investigated by using simulation and measured data.

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24

Schluntz, Justine Oakley. "Tidal turbine array modelling." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:b342fda1-a311-4783-8249-9b1515e0ad62.

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Computational fluid dynamics (CFD) is used in this thesis to model wind and tidal stream turbines and to investigate tidal turbine fence performance. There are two primary objectives of this work. The first is to develop and validate an actuator line method for the simulation of wind and tidal turbines which applies the blade forces to the flow field without the need for a regularisation kernel. The second is to examine tidal fences using, in part, the newly developed actuator line method. A potential flow equivalence method for determining the relative velocity to the blade chord and flow angle at the rotor blades in the actuator line method is proposed and validated. Results for simulations using this method compare favourably with those from both experiments and alternative computational methods, although the present model’s results deviate from experimental results in the vicinity of the blade tips. A CFD-embedded blade element-momentum tool is used to design rotors for operation in infinitely wide tidal fences spanning a tidal channel. Rotors are designed for fences with several different blockage ratios, with those designed for high blockage flows having greater solidity than those designed for operation in fences with lower blockage. It is found that designing rotors for operational blockage conditions can significantly improve the power output achieved by a tidal fence. Improved power output for higher blockage conditions is achieved by the application of greater thrust to the flow. Actuator line simulations of short (up to 8 turbines) fences with varying intra-rotor spacing and number of rotors confirm that hydrodynamic performance of the rotors improves as the spacing is reduced and as rotors are added to a fence. The position of a rotor within the fence impacts its performance; rotors at the ends of a fence extract reduced power compared to those at the centre of the fence, particularly for tip speed ratios greater than the design tip speed ratio.

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25

Garratt, John Edward. "Mathematical modelling of air-rotor-stator interactions in high-speed air-riding bearing and seal technology /." Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580292.

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Air-riding bearing and seal technology comprises rotor and stator elements separated by a thin air-film and experiencing relative rotational motion. The Navier- Stokes equations for compressible flow lead to a modified Reynolds equation incorporating additional high-speed rotation effects. The dynamics of the system are investigated when the axial position of the stator is prescribed by a finite amplitude periodic forcing. Two different physical configurations of air-riding technology are considered in this thesis; a squeeze-film thrust bearing and a pressurised air-riding face seal. Details are provided of a finite-difference, time-stepping scheme and a Fourier spectral collocation scheme to compute the periodic pressure distributions and rotor heights. For changing values of a selected physical parameter the method of arc-length continuation is employed to track branches of solutions computed using the spectral collocation scheme. For both configurations of air-riding technology the effect of different frequencies and amplitudes of stator forcing is identified for a range of rotation speeds and the influence of the rotor support structures is analysed. For air-riding face seals a critical shaft speed is identified that maintains no-net flow by balancing inertia and pressurisation effects The potential for resonant rotor behaviour is identified through asymptotic and Fourier analysis of the rotor motion. Changes in the minimum rotor-stator clearance are presented as a function of the rotor stiffness to demonstrate the appearance of resonance. Both the minimum rotor-stator clearance and the total mass flux of air through the seal are used to evaluate the limits of stable periodic operation without resonant rotor dynamics and incorporating high operating speeds.

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26

Pountney, Oliver. "Modelling and measurement of sealing effectiveness and heat transfer in a rotor-stator system with ingress." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558900.

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This thesis investigates, both theoretically and experimentally, the phenomenon of ingress through gas turbine rim seals. The work presented focuses on modelling and measuring the required sealing flow levels to purge the wheelspace against combined ingress and the effect of externally-induced ingress on the surface temperature and heat transfer to the rotor. Combined ingress is driven by a pressure difference between the mainstream annulus and wheelspace cavity resulting from the combination of the asymmetric external pressure profile in the annulus and the rotation of fluid in the rotor-stator wheelspace cavity. Ingress can be prevented by pressurising the wheelspace through the supply of sealant flow. The Owen (2011b) combined ingress orifice model was solved to predict the required levels of sealant flow to prevent ingress into the wheelspace. The model was validated using prepublished data and data collected experimentally over the course of this research. Gas concentration measurements were made on the stator of the Bath single-stage gas turbine test rig to determine the variation of sealing effectiveness with sealant flow rate for an axial clearance seal geometry at design and off-design operational conditions. The measured variation of the required sealant flow rate with the ratio of the external and rotational Reynolds numbers, ReW / Reϕ, was consistent with the findings of other workers: at low values of ReW / Reϕ, ingress levels were influenced by the combined effects of the disc rotation and the annulus pressure profile and were therefore considered to fall into the combined ingress region; the influence of rotation diminished as ReW / Reϕ increased and the ingress levels were dominated by the annulus pressure field (externally-induced ingress). The orifice model was in good agreement with the experimental measurements and the prepublished experimental data. Thermochromic liquid crystal (TLC) was used to determine effect of ingress on the heat transfer coefficient, h, and adiabatic wall temperature, Tad, on the rotor of the Bath gas turbine rig. Concurrent gas concentration measurements were made on the stator to compare the effects of ingress on the two discs. Data was collected at the design condition, where ReW / Reϕ = 0.538 and at an overspeed off-design condition, where ReW / Reϕ = 0.326. The comparison between a newly defined adiabatic effectiveness, εad, on the rotor and the concentration effectiveness, εc, on the stator, showed that the rotor was protected against the effects of ingress relative to the stator. The sealing air, which is drawn into the rotor boundary layer from the source region, thermally buffers the rotor against the ingested fluid in the core. A thermal buffer ratio, η, was defined as the ratio of the minimum sealant flow required to purge the stator against ingress to the minimum sealant flow required to purge the rotor against ingress. The thermal buffer is dependent upon the flow structure in the wheelspace, which itself is governed the turbulent flow parameter, λT. A hypothesis relating η to λT was developed and shown to be in good agreement with the experimental data. The local Nusselt numbers, Nur, on the rotor were shown to be fairly constant with radius and increased as λT was increased. The latter finding can be explained by the flow structure in the wheelspace: as λT is raised, the swirl in the fluid core reduces, which results in an increase in the moment coefficient and Nur on the rotor. Difficulties in measuring Tad during the experiments suggested a new technique from which to solve for h and Tad using TLC surface temperature measurements. The solution Fourier’s equation for a step-change in the temperature of a fluid flowing over a solid of semi-infinite thickness (the ‘semi-infinite solution’) is limited to relatively low Fourier numbers if Tad is to be calculated accurately. A two-layer composite substrate made from, for example, polycarbonate and Rohacell, could be used to achieve accurate estimates of h and Tad over a larger range of Biot numbers than for a single material substrate. TLC could be used to measure the surface temperature history of the composite substrate during an experiment; this would allow h and Tad to be solved from the numerical solution of Fourier’s equation or from a combination of the semi-infinite and steady-state solutions. The work presented in this thesis has uncovered some interesting findings in areas where research was limited. The measurements of the minimum sealant flow required to purge the wheelspace at off-design operation for a rotor-stator system with blades and vanes and the measurements of the adiabatic effectiveness on a rotating disc affected by ingress are unique and provide a platform for further experimental studies and validation of CFD models.

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27

Rahier, Gilles. "Modelling of airfoil-vortex interaction and application to a helicopter rotor, contribution to blade-vortex interaction noise prediction /." Châtillon : ONERA, 1998. http://catalogue.bnf.fr/ark:/12148/cb367060403.

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28

Hikkaduwa, Liyanage Diana Aroshanie. "Modelling and control of a novel single phase generator based on a three phase cage rotor induction machine." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/250.

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This thesis develops the mathematical modelling and the closed loop control of a single-phase induction generator based on a three-phase cage rotor machine suitable for renewable energy conversion. Comprehensive dynamic and steady state models are developed in stationary ‘αβ’ reference frame and the accuracy is verified by comparing the theoretical results with the laboratory experimental results. Closed loop feedback regulator is designed to regulate the output voltage and frequency at the rated conditions.

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29

Маренич, М. М. "Розробка та дослідження конструкції ротаційного компресора з ротором що котиться. Моделювання коливань ротора". Master's thesis, Сумський державний університет, 2018. http://essuir.sumdu.edu.ua/handle/123456789/72120.

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У дослідній частині поставлені задачі виконати дослідження та проектування резонансних частот коливань ротаційного компресора з ротором що котиться. У конструкторській частині виконано міцнісний розрахунок вала компресора, конструктивні розрахунки підшипників, муфти, ущільнень, клапанів. Визначення основних геометричних розмірів проектованого компресора. Конструктивний розрахунок конденсатора повітряного охолодження. В розділі охорони праці проведено аналіз небезпечних та шкідливих виробничих факторів при роботі ротаційного компресора з ротором що котиться, виконано розрахунок занулення електрообладнання.
В исследовательской части поставленные задачи выполнить исследования и проектирования резонансных частот колебаний ротационного компрессора с ротором что катится. В конструкторской части выполнен прочностной расчет вала компрессора, конструктивные расчеты подшипников, муфты, уплотнений, клапанов. Определение основных геометрических размеров проектируемого компрессора. Конструктивный расчет конденсатора воздушного охлаждения. В разделе охраны труда проведен анализ опасных и вредных производственных факторов при работе ротационного компрессора с ротором что катится, произведен расчет зануления электрооборудования.
In the research part of the task to perform research and design of the resonant frequencies of a rotary compressor with a rotor that rolls. In the design part, the strength calculation of the compressor shaft, structural calculations of bearings, couplings, seals, valves are performed. Determination of the main geometric dimensions of the designed compressor. Constructive calculation of the air-cooled condenser. In the section of labor protection, an analysis of hazardous and harmful production factors has been carried out during the operation of a rotary compressor with a rotor that rolls, the calculation of electrical vanishing has been performed.

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30

Dowell, Andrew. "Windpump modelling, starting hysteresis and the use of a low solidity rotor driving a mono pump through clutched transmission." Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409790.

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31

Chauvicourt, Fabien. "Vibro-acoustics of rotating electric machines: Prediction, Validation and Solution." Doctoral thesis, Universite Libre de Bruxelles, 2018. https://dipot.ulb.ac.be/dspace/bitstream/2013/271049/4/thesis.pdf.

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The increase of greenhouse gas emission is commonly accepted to largely contribute to global warming, in part due to the massive use of non-renewable fossil energy sources. It is a reason why recently, beside other industrial sectors, electric mobility has been considered as the next generation for transportation systems. But the electrification of a vehicle introduces new challenges in its design since it involves different domains of expertise than the ones from Internal Combustion Engine (ICE) vehicles. In particular, Noise, Vibration and Harshness (NVH) comfort is significantly affected by powertrain changes, i.e. from ICE to electric machine. High and unpleasant acoustic noise from resonances may occur but can be addressed numerically to support decision making processes early enough in the design stages. The accurate prediction of its radiated acoustic noise then requires a thorough multi-physical understanding, from the system-level (electric machine) to the component-level (stator and rotor cores).First from a system-level point of view, two multi-physical modeling frameworks that use different model simplifications were implemented. By comparing simulated results to experimental measurements at each physical step of the modeling flow (electromagnetic, vibration, acoustic), it was shown that both models are accurate enough for pre-designing phases. It was also shown that considering only the stator core to contribute to the vibro-acoustic behavior of electric machines is a valid assumption.Second from a component-level point of view, the rotor and the stator core were investigated. The rotor influence on the complete machine structural dynamics was assessed. Beside the validated effects of different rotor topologies on the radiated noise, an analytical model was successfully developed to explain the occurrence of a particular vibration mode; whose explanation was still not offered in literature. In parallel, the stator core was studied, essentially because it is composed of hundreds of thin laminations stacked together which introduce difficulties in understanding its structural behavior. The effects of the laminations on the structural behavior of the stator core were studied numerically and experimentally as well. Two modeling guidelines were thus provided depending on the mode shape of interest and the computational resources available. The experimental studies comforted these two modeling approaches, and also permitted to highlight the importance of looking at the damping properties. Therefore it was shown that different lamination stacking techniques could affect significantly this damping.Finally the influence of the stacking technique (gluing, welding) on the structural behavior of the laminated compound motivated the implementation of an alternative solution to the mitigation of resonance phenomenon responsible for large acoustic noise. By using a skewed distribution of welding or glue lines, the technique aims at forcing laminations to vibrate with different phases which generates friction between them. The induced damping increases and then depends on the introduced asymmetry and on the mode shape considered. This innovative technique was validated experimentally and showed up to 7 times higher structural damping and 10 dB reduction in structural transfer function amplitudes.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished

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32

Ahlström, Anders. "Simulating Dynamical Behaviour of Wind Power Structures." Licentiate thesis, KTH, Mechanics, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1479.

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The workin this thesis deals with the development of anaeroelastic simulation tool for horizontal axis wind turbineapplications.

Horizontal axiswind turbines can experience significanttime varying aerodynamic loads, potentially causing adverseeffects on structures, mechanical components, and powerproduction. The need of computational and experimentalprocedures for investigating aeroelastic stability and dynamicresponse have increased as wind turbines become lighter andmore flexible.

A finite element model for simulation of the dynamicresponse of horizontal axis wind turbines has been developed.The simulations are performed using the commercial finiteelement software SOLVIA, which is a program developed forgeneral analyses, linear as well as non-linear, static as wellas dynamic. The aerodynamic model, used to transform the windflow field to loads on the blades, is a Blade- Element/Momentummodel. The aerodynamic code is developed by FFA (TheAeronautical Research Institute of Sweden) and is astate-of-the-art code incorporating a number of extensions tothe Blade-Element/Momentum formulation. SOSIS-W, developed byTeknikgruppen AB was used to develop wind time series formodelling different wind conditions.

The model is rather general, and different configurations ofthe structural model and various type of wind conditions couldeasily be simulated. The model is primarily intended for use asa research tool when influences of specific dynamic effects areinvestigated.

Simulation results for the three-bladed wind turbine Danwin180 kW are presented as a verification example.

Keywords:aeroelastic modelling, rotor aerodynamics,structural dynamics, wind turbine, AERFORCE, SOSIS-W,SOLVIA

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33

Peng, Wei. "Fast Modelling, Torque-Ripple-Reduction and Fault-Detection Control of Switched Reluctance Motors." Doctoral thesis, Universite Libre de Bruxelles, 2019. https://dipot.ulb.ac.be/dspace/bitstream/2013/285757/5/contratWP.pdf.

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As the world moves towards a cleaner and greener future, electrical machines for various industrial purposes and transport applications have gained a lot of attention. Permanent magnet synchronous machines (PMSMs) are usually the solution for electric vehicle (EV) applications thanks to their high efficiency, compactness and high-power density. On the downside, although the price of rare-earth materials has recovered close to historical levels, concerns still remain and the questions on the environmental sustainability of these materials have also been raised, which has encouraged the researchers to consider rare-earth-free machines.The switched reluctance machine (SRM) is one of the competitive alternatives, thanks to the simple and robust construction, high reliability and inherent fault tolerance capability. However, it has a bad reputation when it comes to torque ripple and acoustic noise. And the highly nonlinear characteristic brings much difficulty to routine design purposes and machine optimisation.Therefore, some of the above mentioned problems are addressed - a torque-ripple-reduction, reliable and low-cost system of SRMs is presented in this thesis. Firstly from the modelling point of view, a combined magnetic equivalent circuit (MEC) and finite element (FE) model of SRMs is developed for fast characterization the nonlinear behavior. Secondly from the control point of view, various torque-ripple reduction techniques are implemented and compared. Moreover, a minimal current sensing strategy with enhanced fault-detection capability is proposed and validated experimentally. It requires two current sensors, to replace the phase current sensors, with no additional devices for fault detection, to achieve a more compact and low-cost drive. Finally from the reliability point of view, an interturn short-circuit fault detection method and a rotor position estimation approach are investigated and validated experimentally, which leads to a more reliable system.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished

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34

Wallin, Mattias. "Measurement and modelling of unbalanced magnetic pull in hydropower generators." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-196490.

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Hydropower research is often perceived to be an old and exhausted field of study but with ageing equipment and the need for more intermittent operation caused by an increased share of other renewable energy sources new challenges lie ahead. The main focus of this dissertation are the electromagnetic forces resulting from nonuniform air gap flux, whether it be caused by rotor eccentricity or a faulty field winding. Results are predominantly obtained from measurements on an experimental generator and numerical simulations. With the computational capacity available today it is possible to numerically analyse physical phenomena that previously could only be studied with analytical tools. Numerical models can also be expanded to encompass more than one aspect of generator operation in coupled field-circuit models without model complexity surpassing computer capability. Three studies of unbalanced magnetic pull, UMP, in synchronous salient pole generators constitute the main part of this thesis. The first is a study of how parallel stator circuits affect the unbalanced magnetic pull caused by rotor eccentricity. Depending on the relationship between the geometry of the separate circuits and the direction of the eccentricity it was found that parallel circuits could reduce the UMP substantially. Secondly, an investigation of the effect of damper winding configuration on UMP was performed. The results showed that damper winding resistivity and the distance between the damper bars in a pole determine the effectiveness of the damper winding in reducing the UMP. Simulations of a production machine indicate that the reduction can be substantial from damper windings with low resistivity. The third study analyses the consequences of field winding interturn short circuits. Apart from a resulting rotating unbalanced magnetic pull it is found that the unaffected poles with the same polarity as the affected pole experience an increase in flux density. In a fourth article a new stand still frequency response, SSFR, test method including measurements of damper winding voltage and current is presented. It is found that the identified models are capable of predicting the stator to damper transfer function both with and without the damper winding measurements included.

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Al, Ibraheemi Mazen. "Modelling and practical set-up to investigate the performance of permanent magnet synchronous motor through rotor position estimation at zero and low speeds." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/115646/.

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This thesis provides a study for the rotor position estimation in SM-PMSMs, particularly at zero and low speeds. The method for zero rotor speed is based on injection of three high frequency voltage pulses in the motor stator windings. Then, the voltage responses at the motor terminals are exploited to extract the rotor position. Two approaches, modelling and practical implementations, are presented. The obtained results have showed a verification of a high-resolution position estimation (a position estimation of 1 degree angle), a simplicity and cost effective implementation and a no need for current sensors is required to achieve the estimation process. It should be noticed that the implementation of rotor position estimation at zero speed is only attended when the rotor is at standstill or very low speed. Therefore, the motor driver is not expected to be active at this condition. Thereby, the zero speed estimation does not provide a robust torque control. In future, this should be taking into consideration to overcome this drawback and to make the estimator more reliable. At low speed running, the primary goal is to start spinning the under test motors, and then the rotor position estimation is achieved. The motor spinning is based on adopting a virtual injected signal to generate the voltage components, Vα and Vβ, of the space vector pulse width modulation technique. Then, generating the eight space vectors is conducted through storing the standard patterns of the six space vector sectors in a memory structure together with the timing sequences of each sector. The presented strategy of motor running includes a proposed motor speed control scheme, which is based on controlling the frequency of the power signal, at the inverter output, through controlling the timing period of execution the power delivery program. The thesis presents a proposed method to achieve the estimation goal depends on tracking the magnetic saliency on one motor line voltage. Thereby, the rotor position estimation The introduced proposed method, for rotor position estimation at zero speed, verifies the following contributions: Ø Presents a simple and cost effective zero speed rotor position estimator for the motor under test. Ø The aimed resolution in this thesis is an angle 1 degree. IV Ø Adopting solely the measuring of motor terminal voltages. Ø Eliminating the detection of the rotor magnet polarity as a necessary technique for completing the position estimation. At low speed running, the following contributions are verified: Ø Rather than a real frequency signal, a virtual injected signal is adopted to generate the voltage components, Vα and Vβ of the space vector pulse width modulation technique. Ø The proposed method for generating the eight space vectors is based on storing the standard patterns of the six sectors in a memory structure together with the timing sequence. Ø The strategy of motor speed control is based on controlling the period of execution the power delivery program. Ø The strategy of low speed rotor position employs one motor line voltage from which the low speed estimation is achieved.

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Arnal, Vincent. "Modélisation expérimentale d'une éolienne flottante par une approche "sofware-in-the-loop"." Thesis, Ecole centrale de Nantes, 2020. http://www.theses.fr/2020ECDN0037.

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Les outils de calcul actuels pour la modélisation numérique multi-physique (vent, vagues, courant, etc.) d’une éolienne flottante ont besoin de validations par des campagnes expérimentales. L’objectif de ce travail est le développement et la validation d’un dispositif expérimental dédié aux essais en bassin à houle d’une éolienne flottante, en se concentrant sur la représentation des efforts du vent. Pour cela, une approche hybride combinant modélisations physique et numérique est développée, appelée “software-in-the-loop” (SIL). Le développement des différentes briques composant un système SIL inclut (i) la sélection et le développement du modèle numérique (ii) le dimensionnement du système de reproduction des efforts (actionneurs) et (iii) la définition de l’environnement temps-réel pour l’intégration du modèle numérique, le contrôle des actionneurs, et l’acquisition des grandeurs mesurables. Pour caractériser et identifier les performances du système SIL, des méthodologies dédiées sont développées. Des bancs d’essais spécifiques sont construits, et des essais en bassin d’une éolienne flottante sont réalisés. Ces essais en bassins sont ensuite comparés à des simulations couplées aéro-hydro-servo structure pour investiguer les hypothèses du modèle d’efforts hydrodynamiques
Actual calculation tools for the multi physical numerical modeling (wind, waves, current, etc.) of a floating wind turbine need validation through experimental campaigns. The objective of this work is the development and validation of an experimental apparatus dedicated to floating wind turbines wave tank testing, focusing on the representation of wind turbine forces. A hybrid approach combining physical and numerical modeling is developed, called “software-in-the-loop” (SIL). The development of the different subsystems of an SIL system includes (i) the selection and development of the numerical model (ii) the design of the force reproduction system (actuators) and (iii) the definition of the real time environment for the integration of the numerical model, the control of actuators, and the data acquisition. To characterize and identify the performances of the SIL system, dedicated methodologies are developed. Specific test benches are built, and wave tank tests of a floating wind turbine are carried out. These wave tank tests are then compared to coupled aero-hydro-servo structure simulations to investigate the hypotheses of the hydrodynamic force model

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VIGNA, VERONICA. "Modelling energy efficiency of complex ship propulsion systems, considering sludge recycling, exhaust gas recovery and Flettner rotors." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1093175.

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Energy efficiency has become increasingly important during the recent years due to the negative effects of the anthropogenic activities on the environment; in the maritime field IMO is leading a steep slope down policy on Greenhouse gas emission reduction by enacting stricter rules at a fast pace. In addition to the environmental and legal aspects, a key driver for increasing energy efficiency is operational cost savings due to fuel consumption reduction. In this framework, the thesis focuses on the improvement of the energy efficiency of the ship propulsion plant by analysing different kind of innovative technologies. Modelling and simulation techniques and appropriate key parameter indicators have been extensively used to provide a suitable metric for bench-marking the different solutions. The reason behind the choice to analyse different technologies is because a well defined solution does not exist. Different ship types and different operational conditions may trigger different options. The first way investigated to improve energy efficiency was by means of an innovative technology to transform sludge into new recycled marine fuel oil through a pyrolysis process carried out in a small reactor onboard. A passenger ship was chosen as a case study due to the advantageous large amounts of waste oil involved and the space availability. The feasibility study and the analysis of fuel consumption reduction and EEOI criticalities are reported: the results showed an easy integration of the system inside the incinerator and a reduction of time and costs; about the environmental aspect, the EEOI formula is not suitable for this innovative technologies and the attempt made to calculate it was unsatisfactory. The results are interesting but not good enough to justify the necessary expenditure investment, also in lieu of the noncalculable impact on the efficiency index. The second investigated solution to further improve the ship efficiency was an innovative flexible propulsion and power system with recovery technologies, studied in collaboration with an Italian shipping company. In the propulsion plant there are dual fuel engines coupled with waste heat recovery systems, innovative hybrid turbocharger and electric power shaft motor/generators. In addition to the description of the propulsion plant and its various modes of use, different configurations are analysed in terms of efficiency and costs and the plant was tested with and without the various recovery systems and with natural gas and HFO, referring to the routes currently travelled by the model ship (a Ro-Ro ferry). The results are expressed as a function of the ship speed: for a given speed and a chosen plant configuration (which recovery systems to consider), the best plant mode of use, among the main three described, is chosen, which means the one associated with the minimum fuel expense. The results showed that the Normal Navigation scenario is the one associated with the lowest fuel costs and highest plant efficiency, for all considered recovery systems. Moreover, they all allow considerable cost savings; in particular, the hybrid turbocharger is the more interesting because the low initial investment is paid off by considerable annual savings. On the other hand, the calculation of the EEDI for each plant configuration shows that only by combining WHRS and hybrid turbocharger together it is possible to respect the IMO limit. After the analysis of said hybrid propulsion system, there was a need to go further to try to integrate renewable sources on board. Therefore the research moved to the wind assisted propulsion, which is gaining in popularity due to the expected benefit in emission reduction. A study was performed about the proper integration between the conventional diesel engine with controllable pitch propeller propulsion plant and the wind assisted plant with Flettner rotor. A mathematical model describing the behaviour of the rotor in terms of propulsive thrust and power is proposed; the rotor model was then integrated into a diesel propulsion model in order to evaluate the ship net fuel consumption for a given wind condition. The integrated propulsion model was written in parametric form. The methodology is intended to support the ship designer during the choice of the best possible propulsion diesel engine for a given rotor-propeller configuration, in addition it can be used to optimize the fuel consumption during the ship operation. A 3000 tons Ro-Ro/Pax ferry has been selected as case study; the results showed that a bigger rotor is always beneficial, that the best directions of incoming wind are from side to astern while the worst case is head wind, that the stronger the wind, the wider the range of suitable angle and that wind angle has a greater influence on the fuel consumption than the wind speed. With the optimized propulsion plant, remarkable double digit power savings can be observed in the whole range of ship speeds, while a 20% of fuel saving was achieved at the design ship speed. The three developed numerical models allow to reduce the environmental impact of the ship and these simulators can be used as a tool to design or operate ships able to meet the present and future energy efficiency requirements. Decarbonisation and environmentally friendly innovations are the real challenges of our century. Therefore, the future of research is strongly linked to the improvement of the energy efficiency and the reduction of environmental impact.

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38

Jaouani, Nassim. "Modelling of installation effects on the tonal noise radiated by counter-rotating open rotors." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC002.

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The Counter-Rotating Open Rotors (CROR) are identified as a possible alternative to turbofan engines for middle-range aircrafts. Providing significant fuel savings and reducing the green-house gas emissions, they may lead however to an increased noise radiation due to the absence of nacelle shielding. To properly predict the acoustic radiation of such systems is then mandatory both to reduce the source mechanisms of the isolated engine and to offer an optimal noise installation solution. Such an objective is tackled in the present thesis in two steps. In a first part, the research aims at predicting the tonal noise radiated from the first propeller of CROR mounted on the rear fuselage by means of a pylon (pusher configuration), considering both the pylon-wake and the uniform ow effects. From the Ffowcs Williams & Hawkings' formalism, three noise sources are identified. First the unsteady loading is computed using a similar procedure to the one used for the rotor-rotor wake interaction noise prediction. The velocity deficit in the pylon wake is locally expanded in two-dimensional Fourier gusts in a reference frame attached to the front rotor. The unsteady lift induced by each gust on a blade segment is calculated using a linearized analytical response function that accounts for a realistic geometry. The steady loading is the second source contribution and is evaluated using both a software based on the lifting-line theory and some numerical simulations for different reference source surfaces. Finally the thickness noise due to the blade volume displacement is included in the analysis using Isom's formulation. From the linear acoustic assumptions, all these sources modelled as equivalent acoustic dipoles rotating in a uniformly moving atmosphere are then summed to calculate the far-field noise. The whole methodology is assessed against wind-tunnel test data and reference software predictions. A parametric study considering several pylon positionings and pylon-wake configurations with blowing is performed in order to emphasize the relative contribution of the three noise sources. Secondly, the rotor- rotor wake interaction noise being recognized as the most significant contribution in isolated configuration, its modelling is completed by introducing the dynamics of the vortex occurring near the rear-rotor leading edge. A semi-analytical methodology is developed to determine a vortex attached over a at plate embedded in a uniform ow with incidence. Applied to the case of a rear blade going through a front-rotor wake, it provides a first estimate of the noise contribution of the vortex
Les hélices contrarotatives constituent une alternative possible aux turboréacteurs pour les avions moyens- courriers. Réduisant significativement la consommation de carburant et les émissions de gaz à effet de serre, ils peuvent néanmoins conduire à un rayonnement sonore accru de par l'absence de carénage. Prédire correctement le rayonnement sonore de telles motorisations est donc indispensable pour réduire les mécanismes sources propres au moteur isolé ou assurer une solution d'installation acoustique optimale. Un tel objectif est abordé dans cette thèse en deux temps. Dans un premier temps, l’étude vise à prédire le bruit tonal rayonné par la première hélice d'un moteur monté à l'arrière du fuselage (configuration dite en pousseur), en considérant les effets du sillage du pylône supportant le moteur et de l'écoulement moyen. Partant du formalisme de Ffowcs Williams & Hawkings, trois sources sonores sont identifiées à cet effet. La charge instationnaire, tout d'abord, est calculée en s'appuyant sur une méthodologie similaire à celle utilisée pour la prédiction du bruit d'interaction de sillages entre les deux rotors. Le déficit de vitesse dans le sillage du mât est décomposé localement en rafales bidimensionnelles dans un repère attaché au rotor amont. La portance instationnaire induite par chaque rafale sur un segment de pale est calculée en utilisant une fonction de réponse analytique linéarisée considérant une géométrie réaliste. Deuxième contribution, la charge stationnaire est évaluée au moyen d'un logiciel s'appuyant sur la théorie de la ligne portante mais également via des simulations numériques pour différentes surfaces sources de référence. Enfin, le bruit d'épaisseur associé au déplacement du volume de la pale est inclus dans l'analyse à partir de la formulation d'Isom. D'après les hypothèses de l'acoustique linéaire, toutes ces sources modélisées comme des dipôles acoustiques tournant dans une atmosphère uniforme en mouvement sont ensuite sommées pour calculer le bruit en champ lointain. L'ensemble de la méthodologie est comparé à des données d'essai et des prédictions d'un logiciel de référence. Une étude paramétrique considérant plusieurs positionnements du pylône et des configurations avec soufflage est effectuée afin de bien mettre en évidence les contributions relatives des trois sources sonores. Dans un deuxième temps, le bruit d'interaction de sillages étant reconnu comme la contribution majoritaire en configuration isolée, sa modélisation est complétée en introduisant la dynamique du tourbillon se développant au voisinage du bord d'attaque du rotor aval. Une méthodologie semi-analytique est développée pour déterminer un tourbillon attaché au-dessus d'une plaque plane plongée dans un écoulement uniforme avec incidence. Appliquée au cas d'une pale aval traversant le sillage du rotor amont, elle fournit une première estimation de la contribution sonore du tourbillon

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Poyi, Gwangtim Timothy. "A novel approach to the control of quad-rotor helicopters using fuzzy-neural networks." Thesis, University of Derby, 2014. http://hdl.handle.net/10545/337911.

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Quad-rotor helicopters are agile aircraft which are lifted and propelled by four rotors. Unlike traditional helicopters, they do not require a tail-rotor to control yaw, but can use four smaller fixed-pitch rotors. However, without an intelligent control system it is very difficult for a human to successfully fly and manoeuvre such a vehicle. Thus, most of recent research has focused on small unmanned aerial vehicles, such that advanced embedded control systems could be developed to control these aircrafts. Vehicles of this nature are very useful when it comes to situations that require unmanned operations, for instance performing tasks in dangerous and/or inaccessible environments that could put human lives at risk. This research demonstrates a consistent way of developing a robust adaptive controller for quad-rotor helicopters, using fuzzy-neural networks; creating an intelligent system that is able to monitor and control the non-linear multi-variable flying states of the quad-rotor, enabling it to adapt to the changing environmental situations and learn from past missions. Firstly, an analytical dynamic model of the quad-rotor helicopter was developed and simulated using Matlab/Simulink software, where the behaviour of the quad-rotor helicopter was assessed due to voltage excitation. Secondly, a 3-D model with the same parameter values as that of the analytical dynamic model was developed using Solidworks software. Computational Fluid Dynamics (CFD) was then used to simulate and analyse the effects of the external disturbance on the control and performance of the quad-rotor helicopter. Verification and validation of the two models were carried out by comparing the simulation results with real flight experiment results. The need for more reliable and accurate simulation data led to the development of a neural network error compensation system, which was embedded in the simulation system to correct the minor discrepancies found between the simulation and experiment results. Data obtained from the simulations were then used to train a fuzzy-neural system, made up of a hierarchy of controllers to control the attitude and position of the quad-rotor helicopter. The success of the project was measured against the quad-rotor’s ability to adapt to wind speeds of different magnitudes and directions by re-arranging the speeds of the rotors to compensate for any disturbance. From the simulation results, the fuzzy-neural controller is sufficient to achieve attitude and position control of the quad-rotor helicopter in different weather conditions, paving way for future real time applications.

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Frias, Anthony. "Minimisation des pertes fer des machines électriques de traction par la modélisation et l'optimisation." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT028/document.

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Le coût, l'autonomie et la durée de vie sont les principaux aspects qui freine le public dans l'achat d'une voiture électrique. Tous ces aspects sont liés à la batterie qui ne permet de stocker qu'une quantité limitée d'énergie. Dans ces conditions, il est indispensable de maîtriser les pertes d'énergie de la chaîne de traction. La machine électrique étant le principal consommateur d'énergie, elle joue un rôle important dans l'efficacité énergétique globale. Dans ce contexte, comment réduire les pertes de la machine électrique pour la rendre plus efficace ? Pour répondre à cette question, l'objectif de ce travail est de modéliser (avec une précision suffisante) et réduire les pertes fer dans notre application machine électrique de traction afin de les maîtriser. On comblera ainsi le manque de confiance en les modèles de pertes fer que peut avoir le concepteur de machine du concepteur de machine en lui permettant de réaliser des optimisations fines jusque dans les dernières phases de développement. Dans la première partie de ce manuscrit, le lecteur découvrira alors une machine synchrone à rotor bobiné du point de vue du matériau magnétique doux. Les premières conclusions montrent qu'une modélisation fine est nécessaire pour bien prendre en compte les phénomènes générateurs de pertes. On s'intéresse également à la mesure des matériaux magnétiques doux afin de comprendre de manière générale et tangible les pertes dans le matériau. On prend également conscience de la toute première source d'incertitude des modèles, la mesure du matériau. Enfin, nous présentons les démarches couramment rencontrées dans la littérature pour la modélisation des pertes fer. Face aux limitations des modèles couramment rencontrés, le modèle LS (un modèle d'hystérésis scalaire qui décompose les pertes en une contribution statique et une contribution dynamique) est redéveloppé afin qu'il réponde encore mieux aux exigences de l'industrie automobile. Il est précis et facilement identifiable à partir de mesures faciles à réaliser. La contribution statique reprend le modèle de Preisach formulé à l'aide des fonctions d'Everett dont l'identification à partir des caractéristiques mesurées est directe. La contribution dynamique quant à elle est dorénavant identifiable à partir de caractérisations en induction sinusoïdales. La précision du modèle ainsi améliorée est ensuite validée sur 63 cas tests exigeants dont la forme de l'induction est à fort contenus harmoniques. Le modèle développé est ensuite couplé avec un modèle électromagnétique élément finis de la machine électrique et validé par l'expérience. Les mesures faites sur le matériau étant l'un des points faibles des modèles, une méthodologie permettant d'évaluer la pertinence de la plage des mesures est proposée. On dresse également un état de l'art de l'impact du process (découpage, empilement et assemblage des tôles) sur les pertes fer afin d'aider le concepteur à mettre en balance les impacts liés au process qui n'ont pu être modélisés. Enfin des méthodologies parmi lesquels, les méthodologies des plans d'expériences sont mises en place afin d'optimiser les cartographies de commandes en des temps de calcul raisonnables. On montre des gains allant jusqu'à 50% de réduction des pertes totales de la machine dans certaines zones de fonctionnement par rapport à une optimisation dont l'objectif serait de minimiser uniquement les pertes dans les conducteurs de la machine. Ces résultats montrent l'intérêt d'utiliser un modèle de pertes fer précis afin de réduire les pertes totales de la machine
Cost, range and lifetime are the main aspects that hold back the consumer to buy electric cars. These three aspects are all related to the battery which stores a limited amount of energy. Under such condition energy consumption is a major concern in electric cars. As the major electricity consumer, electrical machines play a key role for global energy savings. In this context how the electric machine can be made more energy efficient? To answer this question this thesis aim to model (accurately enough) and reduce the iron losses in traction electrical machine for electrical car. Indeed iron loss model suffer from a lack of confidence when it comes to fine optimization during the late phase of development. This thesis answers this question and takes into account the development criteria of the car industry and the constraints of the electric car. The first part of the thesis gives an overview of the application by taking a wounded rotor synchronous machine as a case study. The reader will discover the electrical machine with a soft magnetic material perspective. First, conclusion show that fine modelling of the electric machine is necessary to achieve desired accuracy. An overview on soft magnetic material behavior and measurements is then given. The reader will then acquire a broad feeling on soft magnetic material behavior and understands the first source of inaccuracy of the models (the measurements). Then, the typical models for predicting iron losses in magnetic materials are presented in a literature review. The second part of this study focus on iron loss modelling aspect. The loss surface model (a scalar hysteresis model made of a static and dynamic contribution) is used as the base of this modelling work. The static contribution is re-developed using Everett function formulation of the Preisach model is used to allow easy identification of the model directly from measurements. The identification of the dynamic contribution is re-worked to allow identification from sine-wave measurements (triangular wave measurement previously required). The model accuracy is improved and validated on 63 test cases with high harmonic distortion wave forms. The iron loss model is then coupled to finite element model of the electric machine and the limits of the model are investigated. One of the limits coming from measurement limitation, a methodology to evaluate the relevance of the measurement range is proposed. A literature review of the main impact of the process including cutting, stacking and assembling effects on electrical steel magnetic characteristics is intended to complement the modelling work to help the decision making of the designer on aspects that cannot be modeled. Finally methodologies playing with the modelling hypothesis and involving design of experiment and response surface are presented to reduce computational time and allow the optimization of the control of the machine. The optimizations carried out show total machine loss reduction up to 50% for some working point of the machine compared to an optimization dedicated to minimize only Joule's losses. This results show the interest of using a reliable iron loss model to reduce the total loss of the machine

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41

Haji, Zyad. "Dynamic analysis and crack detection in stationary and rotating shafts." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/dynamic-analysis-and-crack-detection-in-stationary-and-rotating-shafts(2e9dcab4-685d-4c20-8f9d-55b6892b8149).html.

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The sustainability, smooth operation and operational life of rotating machinery significantly rely on the techniques that detect the symptoms of incipient faults. Among the faults in rotating systems, the presence of a crack is one of the most dangerous faults that dramatically decreases the safety and operational life of the rotating systems, thereby leading to catastrophic failure and potential injury to personnel if it is undetected. Although many valuable techniques and models have been developed to identify a crack (or cracks) in stationary and rotating systems, finding an efficient technique (or model) that can identify a unique vibration signature of the cracked rotor is still a great challenge in this field. This is because of the unceasing necessity to develop high performance rotating machines and driving towards significant reduction of the time and cost of maintenance. Most of the crack identification techniques and models in the available literature are based on vibration-based methods. The main idea of the vibration-based method is that the presence of a crack in a rotor induces a change in the mass, damping, and stiffness of the rotor, and consequently detectable changes appear in the modal properties (natural frequencies, modal damping, and mode shapes). Among all these modal properties, the choice of the modal natural frequency change is more attractive as a tool for crack identification. The changes in natural frequencies due to a crack can be conveniently measured from just a few accessible points on the cracked rotor. Furthermore, measuring the natural frequencies does not require expensive measuring instruments, and the natural frequency data is normally less contaminated by experimental noise. However, the change that a crack induces in the natural frequencies is usually very small and can be buried in the ambient noise. Moreover, the natural frequencies are not affected if the crack is located at the nodes of modes or far from the location of inertia force and out-of-unbalance force that the disc generates in the shaft. To overcome these problems (or limitations), therefore, this study is conducted using the idea of the roving mass (roving disc in rotor case). The modal natural frequencies are used for the identification and location of cracks of various severities at different locations in both stationary and rotating shafts. The fundamental idea of the roving disc is that an extra inertia force is traversed along the cracked rotor to significantly excite the dynamics of the rotor near the crack locations. In other words, the location of a crack can be anywhere on the shaft which is contrary to the developed techniques in the available literature in which the location of a crack should be close to the disc. Along with the roving disc idea, three crack identification techniques are developed in this study using the natural frequencies of the cracked and intact shafts. Each of these techniques has its merits and limitations for crack identification. These techniques are implemented using data that are numerically generated by the finite element method based on the Bernoulli-Euler shaft elements and experimentally validated in the laboratory environment. The numerical and experimental results clearly demonstrate the capability of the suggested approach for the identification and location of cracks in stationary and rotating shafts.

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42

Ahlström, Anders. "Aerolastic simulation of wind turbine dynamics." Doctoral thesis, KTH, Mekanik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-157.

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The work in this thesis deals with the development of an aeroelastic simulation tool for horizontal axis wind turbine applications. Horizontal axis wind turbines can experience significant time varying aerodynamic loads, potentially causing adverse effects on structures, mechanical components, and power production. The needs for computational and experimental procedures for investigating aeroelastic stability and dynamic response have increased as wind turbines become lighter and more flexible. A finite element model for simulation of the dynamic response of horizontal axis wind turbines has been developed. The developed model uses the commercial finite element system MSC.Marc, focused on nonlinear design and analysis, to predict the structural response. The aerodynamic model, used to transform the wind flow field to loads on the blades, is a Blade-Element/Momentum model. The aerodynamic code is developed by The Swedish Defence Research Agency (FOI, previously named FFA) and is a state-of-the-art code incorporating a number of extensions to the Blade-Element/Momentum formulation. The software SOSIS-W, developed by Teknikgruppen AB was used to generate wind time series for modelling different wind conditions. The method is general, and different configurations of the structural model and various type of wind conditions can be simulated. The model is primarily intended for use as a research tool when influences of specific dynamic effects are investigated. Verification results are presented and discussed for an extensively tested Danwin 180 kW stall-controlled wind turbine. Code predictions of mechanical loads, fatigue and spectral properties, obtained at different conditions, have been compared with measurements. A comparison is also made between measured and calculated loads for the Tjæreborg 2 MW wind turbine during emergency braking of the rotor. The simulated results correspond well to measured data.
QC 20100826

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Chrin, Phok. "Contribution to electric energy generation for isolated-rural areas using 2nd life components and renewable energies : modelling and control of an induction generator." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30137.

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Le Cambodge est un pays situé en Asie du Sud-Est, avec grand potentiel de ressources en énergies renouvelables. Même fort de ce potentiel, la puissance électrique actuellement installée n'est pas suffisante pour tout le pays. Environ 80% de la population vit dans les zones rurales et 75% des ménages sont sans réseau électrique. Ils utilisent une batterie, le moteur diesel, des bougies ou du kérosène pour l'éclairage, la télévision, les multimédia et autres appareils ménagers. Une minorité des citoyens, dans la partie nord utilise des modules pico hydro électriques acheté dans les pays voisins pour éclairage. Mais la tension de sortie et la fréquence ne sont pas vraiment stables en cas de modification de la charge ou de la vitesse de rotation de la turbine. La durée de vie des appareils électroménagers peut ainsi être réduite et des réparations locales sont nécessaires. Des millions de Cambodgiens ne peuvent pas accéder à l'énergie électrique en raison de deux facteurs principaux : les barrières technologiques et les coûts d'investissement élevés. Nos activités de recherche visent à éliminer ces barrières technologiques en concevant des systèmes de production d'énergie pico-hydroélectrique avec une installation rapide et peu coûteuse, simple et adaptée à une application locale tout en gardant une qualité de l'alimentation électrique satisfaisante. La première partie de cet ouvrage décrit la situation de l'énergie dans les zones rurales du Cambodge où les gens sont confrontés à un manque d'alimentation électrique. En conséquence, ils ne peuvent ni améliorer leur niveau de vie, ni développer leur communauté. Les villageois riches utilisent une batterie de voiture, des systèmes photovoltaïques ou pico-hydroélectriques alors que les villageois pauvres utilisent des bougies ou du kérosène pour l'éclairage. Des entreprises locales fournissent des solutions électriques basées sur des énergies renouvelables, mais les prix sont inabordables et loin de leurs attentes. Par conséquent, une solution originale est proposée dans cette thèse avec la récupération de composants électriques d'occasion en vue de la mise en œuvre d'un nouveau système de génération d'électricité pour les zones rurales isolées. Il s'agit ici d'innovation frugale pour le bas de la pyramide sociale. Les composants utilisés sont : machine asynchrone, alimentation sans interruption (UPS), alimentation de PC et d'autres équipements électroniques, etc. Ces composants recyclés peuvent être rassemblés pour former ainsi une solution technologique intéressante permettant de délivrer la puissance de sortie nécessaire. La deuxième partie de ce mémoire présente la modélisation de l'étage de puissance de la machine asynchrone triphasée utilisée comme un générateur asynchrone monophasé avec une phase d'excitation et les deux autres phases connectées en série pour alimenter la charge. Cette configuration est nommée 'Excited Induction Generator (EIG)'
Cambodia is a country located in Southeast Asia, with its high potential of renewable energy resource. Even if this country has a high potential for renewable, the installed power is still not high enough to cover the whole country. About 80% of population living in rural areas and 75% of the households live without electricity. They survive by using battery, diesel engine, candle, kerosene for lighting, TV, multimedia and some other household appliances. A few of residents in northern part of the country use pico-hydro power units bought from neighbor countries in order to electrify their houses. In these systems, the output voltage and frequency are not really stable while the load under load or speed variations. Consequently, the lifetime of household appliances could be reduced or the items damaged and local repairs are needed. Moreover, millions of Cambodian people cannot access neither take an advantage from the available energy resources due to two main factors: technology barriers and high investment cost. This research aims to remove technology barriers by designing simple systems for pico-hydro power generation with fast and simple installation, suitable for local applications with high quality of electrical supply. The first part of this work briefly describes the energy situation in rural areas of Cambodia where people are facing the lack of electrical supply which. They cannot neither improve their living standard nor develop their community. Rich villagers use car battery, solar PV applications, pico-hydro power while poor villagers use candle/kerosene for lighting. Local enterprises can provide renewable energy solutions but the prices are unaffordable and far from their expectations. Therefore, an original solution is proposed in this thesis by using wasted electric and electronic equipment (second-life components) to form the new power generation systems for remote rural areas. This is frugal innovation to serve the bottom of the social pyramid. The used components are: induction machine, Uninterrupted Power Supply (UPS), power supply of a computer and other electronic equipment, etc. These wasted components can be arranged together to form a good solution with an interesting output power. The second part of this thesis presents the modelling of the power stage of three-phase induction machine as a single-phase induction generator by using one phase for excitation while the other two phases are connected in series to supply load, named "Excited Induction Generator (EIG)". Capacitor banks are added to EIG for compensating the reactive power. Capacitor values influence poles and zeros locations which are described and analyzed in the root locus according to the parameter variations. The third part of this thesis is devoted to onsite modelling of losses in induction machine. The method should achieve results simply, rapidly, without any prior information on the machine, in order to further integrate this model into energy optimization algorithms. Design of experiments is a good candidate. Experimental models of the total loss (iron loss and rotor copper losses) are proposed for motor operation and generator mode for different machines of different powers. The last part of this thesis describes output voltage/current response for both simulation results and experimental results of the induction generators. Proportional-integral and proportional-resonant controllers are tested. The implementation of closed loop controller is first achieved in an analog circuit and then, with dSPACE/MATLAB Simulink environment

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44

Logan, Thomas George. "Harmonic analysis of the brushless doubly-fed machine including single-phase operation." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/252277.

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45

Bradley, William J. "Current Based Fault Detection and Diagnosis of Induction Motors. Adaptive Mixed-Residual Approach for Fault Detection and Diagnosis of Rotor, Stator, Bearing and Air-Gap Faults in Induction Motors Using a Fuzzy Logic Classifier with Voltage and Current Measurement only." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/7265.

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Induction motors (IM) find widespread use in modern industry and for this reason they have been subject to a significant amount of research interest in recent times. One particular aspect of this research is the fault detection and diagnosis (FDD) of induction motors for use in a condition based maintenance (CBM) strategy; by effectively tracking the condition of the motor, maintenance action need only be carried out when necessary. This type of maintenance strategy minimises maintenance costs and unplanned downtime. The benefits of an effective FDD for IM is clear and there have been numerous studies in this area but few which consider the problem in a practical sense with the aim of developing a single system that can be used to monitor motor condition under a range of different conditions, with different motor specifications and loads. This thesis aims to address some of these problems by developing a general FDD system for induction motor. The solution of this problem involved the development and testing of a new approach; the adaptive mixed-residual approach (AMRA). The main aim of the AMRA system is to avoid the vast majority of unplanned failures of the machine and therefore as opposed to tackling a single induction motor fault, the system is developed to detect all four of the most statistically prevalent induction motor fault types; rotor fault, stator fault, air-gap fault and bearing fault. The mixed-residual fault detection algorithm is used to detect these fault types which includes a combination of spectral and model-based techniques coupled with particle swarm optimisation (PSO) for automatic identification of motor parameters. The AMRA residuals are analysed by a fuzzy-logic classifier and the system requires only current and voltage inputs to operate. Validation results indicate that the system performs well under a range of load torques and different coupling methods proving it to have significant potential for use in industrial applications.
The full-text was made available at the end of the embargo period on 29th Sept 2017.

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46

Bradley, William John. "Current based fault detection and diagnosis of induction motors : adaptive mixed-residual approach for fault detection and diagnosis of rotor, stator, bearing and air-gap faults in induction motors using a fuzzy logic classifier with voltage and current measurement only." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/7265.

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Анотація:

Induction motors (IM) find widespread use in modern industry and for this reason they have been subject to a significant amount of research interest in recent times. One particular aspect of this research is the fault detection and diagnosis (FDD) of induction motors for use in a condition based maintenance (CBM) strategy; by effectively tracking the condition of the motor, maintenance action need only be carried out when necessary. This type of maintenance strategy minimises maintenance costs and unplanned downtime. The benefits of an effective FDD for IM is clear and there have been numerous studies in this area but few which consider the problem in a practical sense with the aim of developing a single system that can be used to monitor motor condition under a range of different conditions, with different motor specifications and loads. This thesis aims to address some of these problems by developing a general FDD system for induction motor. The solution of this problem involved the development and testing of a new approach; the adaptive mixed-residual approach (AMRA). The main aim of the AMRA system is to avoid the vast majority of unplanned failures of the machine and therefore as opposed to tackling a single induction motor fault, the system is developed to detect all four of the most statistically prevalent induction motor fault types; rotor fault, stator fault, air-gap fault and bearing fault. The mixed-residual fault detection algorithm is used to detect these fault types which includes a combination of spectral and model-based techniques coupled with particle swarm optimisation (PSO) for automatic identification of motor parameters. The AMRA residuals are analysed by a fuzzy-logic classifier and the system requires only current and voltage inputs to operate. Validation results indicate that the system performs well under a range of load torques and different coupling methods proving it to have significant potential for use in industrial applications.

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47

Trchalik, Josef. "Aeroelastic modelling of gyroplane rotors." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/1232/.

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The gyroplane represents the first successful rotorcraft design and it paved the way for the development of the helicopter during the 1940s. Gyroplane rotors are not powered in flight and work in autorotative regime and hence the characteristics of a helicopter rotor during powered flight and a rotor in autorotation differ significantly. Gyroplanes in the UK have been involved in number of fatal accidents during the last two decades. Despite several research projects focused on gyroplane flight dynamics, the cause of some of gyroplane accidents still remains unclear. The aeroelastic behaviour of autorotating rotors is a relatively unexplored problem and it has not yet been investigated as possible cause of the accidents. A mathematical model was created to simulate aeroelastic behaviour of rotors in autorotation. The model can investigate couplings between blade teeter, bending, torsion and rotor speed using a finite element model combined with a blade element method and a dynamic inflow model. A set of 'McCutcheon' rotor blades was subjected to a series of experiments, yielding baseline input parameters for the model. The model was validated against published results of modal analysis of helicopter rotor blades, experimental flight measurements and other data published in open literature. Effect of selected rotor design parameters on performance and stability of autorotating rotors was analyzed. Results of the model suggest that steady autorotative flight is not possible for excessive values of blade fixed incidence angle or geometric twist of the blade, leading to an aeromechanical instability. Negative values of these parameters lead to rotor over-speed, loss of rotor thrust and increase in vehicle speed of descent. The simulations have shown that moderate values of blade geometric twist applied to the inboard region of the blade together with blade tip mass can improve stability of a rotor in autorotation. A significant part of the research was focused on investigation of the effect of different values of torsional and flexural stiffness, and the relative chord-wise positions of blade elastic axis and centre of mass on rotor stability during autorotation. The results obtained from the model demonstrate an interesting and unique characteristic of the autorotative regime. Coupled flap-twist-rotor speed oscillations of the rotor occur if the torsional stiffness of the blade is lower than a critical value and if the blade centre of mass is aft of the blade elastic axis. The new type of aeroelastic instability is specific to autorotating rotors and differs from both helicopter rotor flutter and fixed-wing flutter. An extra degree of freedom in rotor speed does not alter flutter onset point significantly and hence this instability can be classified as pitch-flap flutter, with the stability boundary of a hyperbolic shape. However, variation of rotor speed in response to coupled flexural and torsional dynamics of the rotor blades changes behaviour of the rotor during the instability. The coupling of rotor teeter, blade torsion and rotor speed with vehicle speed of descent results in a combined flutter and divergence instability. The investigation aeroelastic behaviour of rotors in autorotation has shown that although autorotation has strong autostabilizing character, catastrophic aeroelastic instability can occur. Aeroelastic instability of this type has not been previously described in open literature. The instability can be initiated by incorrect mass balance of the rotor blades together with their insufficient torsional stiffness. Alternatively, unsuitable rotor geometry causing excessive blade incidence can prevent the rotor from entering steady autorotation. Hence a rotor in autorotation with unsuitable design of rotor blades can encounter an aeroelastic instability even if it is correctly mass balanced.

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48

Roux, Louis. "Modélisation dynamique du départ d'une pale et de la tenue des pales suiveuses dans une turbomachine." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI056.

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Lors de la phase de certification d’un turbomoteur, le motoriste doit démontrer que la perte d’une pale de rotor ne conduit pas au "Knocking-Off", c’est à dire à la rupture en cascade des pales suiveuses. Cette démonstration est faite en général par un essai au banc coûteux car partiellement destructif. Grâce à l’amélioration des moyens de calcul, il devient possible de simuler la réponse transitoire de la structure soumise à ce type de chargement très complexe. En tant que point d’entrée sur la simulation, la connaissance du comportement des matériaux est primordiale. Or, peu d’études sont publiées sur le comportement dynamique des superalliages à base nickel monocristallins et, de surcroît, à des températures élevées de l’ordre de 1000°C. Pour prédire efficacement les conséquences d’impacts sur des pales de turbines, des travaux expérimentaux et numériques ont été réalisés sur un monocristal couramment utilisé par Turbomeca. Des essais de compression dynamique à haute température sur barres de Hopkinson permettent d’estimer le seuil de plasticité et l’écrouissage du matériau en fonction de l’orientation du cristal, de la vitesse de déformation et de la température. Les paramètres d’une loi visco-plastique anisotrope sont identifiés pour modéliser efficacement le comportement macroscopique du MC2 sous des chargements intenses et fortement multi-axiaux. Une campagne d’essais balistiques au banc de Safran Snecma a été réalisée sur des plaques et des pales monocristallines à hautes températures. Afin de prendre en compte la fragmentation des profils dans les calculs de perte de pale, un critère en déformation plastique dépendante du taux de triaxialité des contraintes est calibré puis validé par confrontation aux essais de tirs sur plaques. Des mesures de stéréo-corrélation postmortem et des enregistrements à la caméra rapide permettent de valider les simulations. Une pratique de modélisation de la perte d’une pale avec l’outil LS-Dyna a été établie et appliquée à un cas industriel de perte de pale en service. Enfin, en vue de justifier le découplage temporel entre les dommages primaires, liés aux impacts directs sur les premières pales suiveuses, et secondaires, liés aux effets de l’excentration, une approche de dynamique d’ensemble de ligne d’arbre a été développée puis validée
During the certification process of a turbo engine, the engine manufacturer has to demonstrate that the loss of a rotor blade does not lead to the "knocking-off" phenomenon, in other words to the cascading failure of the successive blades. Generally, this demonstration is carried out through a costly rig test driving to the partial destruction of the engine. Thanks to the improvement of computational resources, it is now possible to simulate the transient response of the structure subjected to this complex loading. The knowledge of material behavior turns out to be the essential starting point for the simulation. However, only a few studies have been published on the dynamic behavior of nickel-based single crystal superalloys at high temperature reaching 1000°C. With a view to efficiently predicting the consequences of impacts on turbine blades, experimental and numerical works have been conducted on a single crystal frequently used by Turbomeca. High-temperature dynamic compressive tests on Split Hopkinson Pressure Bars (SHPB) have enabled to estimate the material plasticity level and hardening, depending on the crystal orientation, strain rate and temperature. The parameters of a viscoplastic anisotropic law have been identified to effectively model the MC2 macroscopic behavior under highly intense and multiaxial loading. At Safran Snecma Villaroche, ballistic tests have been undertaken on both single crystal plates and blades under high temperatures. In order to consider the fragmentation of profiles in blade-off simulations, a plastic strain criterion depending on stress triaxiality has been calibrated and validated by comparison with the impacts on blades. Post-mortem digital images correlation measurements and high-speed camera recordings have confirmed these simulations. Using LS-Dyna solver, a blade-off modeling strategy has been created and applied to an actual blade-off industrial case. Finally, a rotordynamics approach has been developed and validated with the aim of separately analyzing the primary damage, caused by direct impacts on the first following blades, and the secondary damage due to the effects of unbalance on a flexible rotor

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49

Gustavsson, Rolf. "Modelling and analysis of hydropower generator rotors /." Luleå, 2005. http://epubl.luth.se/1402-1757/2005/62.

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50

Banejad, Mahdi. "Identification of damping contribution from power system controllers." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15851/1/Mahdi_Banejad_Thesis.pdf.

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With the growth of power system interconnections, the economic drivers encourage the electric companies to load the transmission lines near their limits, therefore it is critical to know those limits well. One important limiting issue is the damping of inter-area oscillation (IAO) between groups of synchronous machines. In this Ph.D. thesis, the contribution of power system components such as load and static var compensators (SVC) that affect the IAO of the power system, are analysed. The original contributions of this thesis are as follows: 1-Identification of eigenvalues and mode shapes of the IAO: In the first contribution of this thesis, the eigenvalues of the IAO are identified using a correlation based method. Then, the mode shape at each identified resonant frequency is determined to show how the synchronous generators swing against each other at the specific resonant frequencies. 2-Load modelling and load contribution to damping: The first part of this contribution lies in identification of the load model using cross-correlation and autocorrelation functions . The second aspect is the quantification of the load contribution to damping and sensitivity of system eigenvalues with respect to the load. 3- SVC contribution to damping: In this contribution the criteria for SVC controller redesign based on complete testing is developed. Then the effect of the SVC reactive power on the measured power is investigated. All of the contributions of this thesis are validated by simulation on test systems. In addition, there are some specific application of the developed methods to real data to find a.) the mode shape of the Australian electricity network, b.) the contribution of the Brisbane feeder load to damping and c.) the effect of the SVC reactive power of the Blackwall substations on the active power supplying Brisbane.

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