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Dissertations / Theses on the topic 'Helicopter rotor blade design'
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1
Collins, Kyle Brian. "A multi-fidelity framework for physics based rotor blade simulation and optimization." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26481.
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Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2009.Committee Co-Chair: Dr. Dimitri Mavris; Committee Co-Chair: Dr. Lakshmi N. Sankar; Committee Member: Dr. Daniel P. Schrage; Committee Member: Dr. Kenneth S. Brentner; Committee Member: Dr. Mark Costello. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Tamer, Aykut. "Analysis And Design Of Helicopter Rotor Blades For Reduced Vibrational Level." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613661/index.pdf.
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In this thesis analysis and design of helicopter rotor blades were discussed for reduced
vibrational level. For this purpose an optimization procedure was developed which involves
coupling of the comprehensive rotorcraft analysis tool CAMRAD JA and the gradient based
optimization algorithm. The main goal was to achieve favorable blade structural dynamics
characteristics that would lead to reduction in vibrational level. For this purpose blade
stiffness and mass distributions were considered as the design variables. In order to avoid
likely occurrences of unrealistic results, the analyses were subjected to constraints which
were sensitive to the design variables. The optimization procedure was applied on two
isolated rotor blades and a full helicopter with main rotor, tail rotor and fuselage by using
natural frequency separation and hub load minimization respectively. While the former
approach relied on the blade natural frequencies, the latter approach involved higher
harmonic aerodynamic and blade motion calculations. For both approaches, the
improvement in vibration characteristics and blade mass and stiffness distributions of the
initial design and the design after optimization analyses were compared and discussed.
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Tapia, Fidencio. "Inverse methodology for multi-point aerodynamic rotor blade design." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/13335.
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Sarker, Pratik. "Dynamic Response of a Hingeless Helicopter Rotor Blade at Hovering and Forward Flights." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2545.
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The helicopter possesses the unrivaled capacity for vertical takeoff and landing which has made the helicopter suitable for numerous tasks such as carrying passengers and equipment, providing air medical services, firefighting, and other military and civil tasks. The nature of the aerodynamic environment surrounding the helicopter gives rise to a significant amount of vibration to its whole body. Among different sources of vibrations, the main rotor blade is the major contributor. The dynamic characteristics of the hingeless rotor consisting of elastic blades are of particular interest because of the strongly coupled equations of motion. The elastic rotor blades are subjected to coupled flapping, lead-lag, and torsional (triply coupled) deflections. Once these deflections exceed the maximum allowable level, the structural integrity of the rotor blade is affected leading to the ultimate failure. The maximum deflection that a blade can undergo for a specific operating condition needs to be estimated. Therefore, in this study, the triply coupled free and forced response of the Bo 105 hingeless, composite helicopter rotor blade is investigated at hovering and forward flights. At first, a model of the composite cross-section of the rotor blade is proposed for which a semi-analytical procedure is developed to estimate the sectional properties. These properties are used in the mathematical model of the free vibration of the rotor blade having the proposed cross-section to solve for the natural frequencies and the mode shapes. The aerodynamic loadings from the strip theory are used to estimate the time-varying forced response of the rotor blade for hovering and forward flights. The large flapping and inflow angles are introduced in the mathematical model of the forward flight and the corresponding nonlinear mathematical model requires a numerical solution technique. Therefore, a generalization of the method of lines is performed to develop a robust numerical solution in terms of time-varying deflections and velocities. The effect of the unsteady aerodynamics at the forward flight is included in the mathematical model to estimate the corresponding dynamic response. Both the analytical and the numerical models are validated by finite element results and the convergence study for the free vibration is performed.
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Gündüz, Mustafa Emre. "Software integration for automated stability analysis and design optimization of a bearingless rotor blade." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33916.
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The concept of applying several disciplines to the design and optimization processes may not be new, but it does not currently seem to be widely accepted in industry. The reason for this might be the lack of well-known tools for realizing a complete multidisciplinary design and analysis of a product. This study aims to propose a method that enables engineers in some design disciplines to perform a fairly detailed analysis and optimization of a design using commercially available software as well as codes developed at Georgia Tech. The ultimate goal is when the system is set up properly, the CAD model of the design, including all subsystems, will be automatically updated as soon as a new part or assembly is added to the design; or it will be updated when an analysis and/or an optimization is performed and the geometry needs to be modified. Such a design process takes dramatically less time to complete; therefore, it should reduce development time and costs. The optimization method is demonstrated on an existing helicopter rotor originally designed in the 1960's. The rotor is already an effective design with novel features. However, application of the optimization principles together with high-speed computing resulted in an even better design. The objective function to be minimized is related to the vibrations of the rotor system under gusty wind conditions. The design parameters are all continuous variables. Optimization is performed in a number of steps. First, the most crucial design variables of the objective function are identified. With these variables, Latin Hypercube Sampling method is used to probe the design space of several local minima and maxima. After analysis of numerous samples, an optimum configuration of the design that is more stable than that of the initial design is reached. The process requires several software tools: CATIA as the CAD tool, ANSYS as the FEA tool, VABS for obtaining the cross-sectional structural properties, and DYMORE for the frequency and dynamic analysis of the rotor. MATLAB codes are also employed to generate input files and read output files of DYMORE. All these tools are connected using ModelCenter.
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Prechtl, Eric Frederick. "Design and implementation of a piezoelectric servo-flap actuation system for helicopter rotor individual blade control." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9266.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000.Includes bibliographical references (p. 177-186).
A novel new actuator for helicopter rotor control, the X-Frame Actuator, was developed, demonstrating superior performance for applications requiring compact, fast acting, large stroke actuation. The detailed experimental characterization of this actuator is described, including bench-top output energy measurements and transverse shake test performance. A Mach scaled rotor blade utilizing the X-Frame actuator to power a trailing edge servo-flap near the tip was also designed, manufactured and tested. A description of the design and composite manufacturing of the rotor blade and servo-flap is presented. Preliminary bench tests of the active blade actuation system are also presented. The hover tests of the active blade provided transfer function identification of the performance of the actuator in producing flap deflections, and the response of the rotor from deflections of the servo-flap. At the highest field level of 60 V/mil P-P the actuation system produces 7.75 degrees of quasi-static peak-to-peak flap deflection in hover. The servo-flap produces significant control authority, especially near the 3/rev frequency that would be important for the CH-47. Scaled to a full-sized CH-47, the rotor can produce over 16,000 lb peak-to-peak thrust variation at 3/rev, which is 32% of the aircraft's gross weight. Closed-loop feedback control was experimentally applied to the model rotor system. Both single frequency and combined frequency controllers were successfully implemented on the rotor. Most significantly, simultaneous control of 1/rev, 3/rev, 4/rev, 5/rev, and 6/rev harmonic vibration has been successfully demonstrated. The peak vibrations were eliminated at each frequency, as well as the vibrations over a small bandwidth surrounding each peak. Experimental comparison of continuous time versus discrete time control has shown the former to be a more effective approach for vibration reduction.
by Eric Blade Prechtl.
Ph.D.
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Tatossian, Charles A. "Aerodynamic shape optimization via control theory of helicopter rotor blades using a non-linear frequency domain approach." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112586.
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This study presents a discrete adjoint-based aerodynamic optimization algorithm for helicopter rotor blades in hover and forward flight using a Non-Linear Frequency Domain approach. The goal is to introduce a Mach number variation into the Non-Linear Frequency Domain (NLFD) method and implement a novel approach to present a time-varying cost function through a multi-objective adjoint boundary condition. The research presents the complete formulation of the time dependent optimal design problem. The approach is firstly demonstrated for the redesign of a NACA 0007 and a NACA 23012 helicopter rotor blade section in forward flight. A three-dimensional inviscid Aerodynamic Shape Optimization (ASO) algorithm is then employed to validate and redesign the Caradonna and Tung experimental blade. The results in determining the optimum aerodynamic configurations require an objective function which minimizes the inviscid torque coefficient and maintains the desired thrust level at transonic conditions.
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Paris, Manuel. "Identification du comportement en torsion à fort facteur d’avancement des pales d’hélicoptère conventionne : application à la réduction des efforts de commandes sur une formule hybride haute vitesse de type X3." Thesis, Paris, ENSAM, 2014. http://www.theses.fr/2014ENAM0045.
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L'augmentation de la vitesse de croisière des hélicoptères à architecture conventionnelle (rotor principal et rotor anticouple) atteint aujourd'hui une asymptote. Le concept X3, associant 2 hélices et une aile pour alléger la charge du rotor principal, propose une solution viable économiquement, qui s'appuie sur l'utilisation de technologies éprouvées telles que le rotor Spheriflex® du Dauphin. Les essais en vol menés sur le démonstrateur X3 ont montré un bon comportement en performances et en qualités de vol de ce type de rotor, mais un niveau de charges très importants dans les commandes de vol. Pour limiter la masse à vide, la solution de surdimensionner toutes les pièces mécaniques n'est pas envisageable. Ce travail de thèse propose d'étudier les opportunités de réduction des efforts de commandes.Afin de pouvoir réduire ces efforts, il a été nécessaire de comprendre leur origine et de proposer une modélisation qui permette de les prédire. Des mesures expérimentales réalisées sur le démonstrateur X3 ont permis d'identifier les excitations aérodynamiques et le comportement dynamique des pales en torsion. Les phénomènes responsables de l'augmentation des efforts de commande ont été identifiés, ce qui a permis de corriger le modèle de calcul des efforts de commande HOST actuellement utilisé par Airbus Helicopters.A partir du logiciel HOST corrigé et de la compréhension des phénomènes physiques, des solutions technologiques pour réduire les efforts de commandes ont été étudiées. Deux familles de solutions sont alors considérées : l'optimisation du système de commandes de vol et la réduction des efforts dans les bielles de pas. L'optimisation du système de commandes de vol permet d'obtenir une réduction significative des efforts de commandes grâce à un algorithme d'optimisation de l'architecture de placement des servocommandes. L'étude de la réduction des efforts dans les bielles de pas montre que le choix de l'équilibre appareil conduit à des opportunités de réduction des efforts de commandes, alors que la modification du design de pale n'apporte pas de réduction notable et engendre une diminution des performances en stationnaireNowadays, the increase of cruise speed for conventional helicopters (main rotor and anti-torque rear rotor) reaches an asymptote. The X3 concept proposed by Airbus Helicopters is a hybrid helicopter combining 2 propellers at the tip of small wings in order to unload the main rotor. This solution is economically viable because it reuses well-proven technologies such as the Spheriflex rotor, already used on the Dolphin family for many years. X3 flight tests have shown a good behavior of the rotor concerning performances as well as handling qualities, but control loads in the rotor system were significantly higher in cruise conditions than for conventional helicopters. In order to save the payload, over-sizing of the mechanical parts in order to withstand these loads can't be an appropriate solution. The work presented in this thesis deals with the problematic of control loads reduction.In order to reduce the control loads, the first step is to highlight the roots of these loads and to get a predictive tool over the whole flight domain. Experimental measurements from X3 flight tests give the aerodynamic loads on the blade sections, leading to understand the blades torsional dynamic behavior in several flight test cases (cruise, turns and high speed flight). Phenomena responsible for the increase of control loads are then identified, and the rotor computation tool HOST used at Airbus Helicopters is corrected to predict accurately control loads over the conventional as well as the high speed helicopter flight domain.The corrected rotor computation tool HOST, associated with the physical comprehension of the blade torsional dynamics, is used to quantify the possible solutions proposed for control loads reduction. Two main ways are studied: the optimization of the control system architecture and the reduction of pitch link loads. The optimization of control system architecture shows a dramatic reduction of control loads in the servo actuators and in the non-rotating scissors, thanks to an optimization algorithm developed during this thesis. The reduction of pitch link loads study shows that the optimization of the helicopter equilibrium leads to drastic reduction, whereas the modification of blade design does not show any significant reduction even at high speed
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Fox, Matthew Edward. "Blade mounted actuation for helicopter rotor control." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/49586.
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Garcia, James Christopher. "Active helicopter rotor control using blade-mounted actuators." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36436.
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Bailey, Brent. "Investigation of a composite hingeless helicopter rotor blade with integral actuators." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0024/MQ52385.pdf.
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Bailey, Brent Carleton University Dissertation Engineering Mechanical and Aerospace. "Investigation of a composite hingeless helicopter rotor blade with integral actuators." Ottawa, 2000.
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Ikuta, Masahiko Kuzume. "Analysis of blade-mounted servoflap actuation for active helicopter rotor control." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/46450.
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Wickramasinghe, Viresh K. (Viresh Kanchana) 1971. "Characterization of active fiber composite actuators for helicopter rotor blade applications." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/82200.
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Lovaco, Jorge Luis. "Verication of a Modelica Helicopter Rotor Model Using Blade Element Theory." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-142055.
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Helicopters have been valuable vehicles ever since their invention. Their capabilities for axial flight and hovering make them an outstanding resource. However, their complexity, directly related to their aerodynamics, makes them extremely hard to design. In today’s market competitivity resources must be optimized and accurate models are needed to obtain realizable designs. The well known Blade Element Theory was used to model helicopter rotors using the Modelica based software SystemModeler. However, it remained unverified due to the lack of experimental data available. The access to experimental data published by NASA motivated the comparison from the model to the measurements obtained during real testing to a scaled rotor. Some improvements were performed to the model obtaining unexpectedly accurate results for hover and axial flight. Two approaches based on the Blade Element Theory and related to Vortex Theory were followed: an infinite number of blades and a finite number of blades. Moreover, the model simulation speed was notice ably increased and prepared for the forward flight model development. Nonetheless, even though the model was ready for forward flight simulations, further research is needed due to, again, the lack of experimental data available. It is concluded from the present work that Wolfram’s SystemModeler can be used as a tool in early design phases of helicopters, even before CAD modeling and CFD due to its simplicity, speed, accuracy, and especially its capability for being used on simple desktop computers.
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Gómez, Jon Freire. "Active gurney flap mechanism for a full scale helicopter rotor blade." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690378.
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Amongst the objectives of the EU's Green Rotorcraft programme is the development of a functional and airworthy Active Gurney Flap (AGF) for a full-scale helicopter rotor blade. Interest in the development of this 'smart adaptive rotor blade' technology lies in its potential to provide a number of aerodynamic benefits, which would in turn translate into a reduction in fuel consumption and noise levels. With a technical specification informed by helicopter manufacturer Agusta Westland as a starting point, the AGF concept developed emerged from the application of a design methodology consisting of an initial concept generation phase and a subsequent selection process based on a series of problem-specific qualitative and quantitative performance criteria. This methodology resulted in a novel AGF concept design where the use of flexural pivots was favoured over bearing-type joints. As a first step towards full validation of both the concept design and the theoretical aerodynamic benefits of the AGF, a baseline design of the mechanism was successfully tested both in a fatigue rig and in a 2D wind tunnel environment at flight-representative deployment schedules. This baseline design was then reengineered with a view to making it fit for flight test. However, analysis of the flight test baseline design under full in-flight loading and blade deformations revealed that the stresses arising in the flexures exceeded the allowable limits. In order to overcome this problem, two complementary alternatives were investigated. Initially, a generic 2D and 3D shape optimisation of leaf-type crossed flexure pivot springs was carried out considering the pivots as individual isolated elements. This route produced important novel results in the field of crossed flexure pivots and proved that there is great scope for stress reduction through shape optimisation. Furthermore, a parametric optimisation of the AGF mechanism as a whole was performed, where the effect of a range of topological parameters was investigated. This second approach resulted in very significant stress reductions" sufficient so as to conclude that the proposed AGF concept has potential to become an airworthy design, although further work is needed to achieve a sufficiently mature technology readiness level.
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King, Robert L. "Nonlinear dynamics in the modeling of helicopter rotor blade lead/lag motion." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA366866.
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Dissertation (Ph.D. in Aeronautical and Astronautical Engineering) Naval Postgraduate School, June 1999."June 1999". Dissertation supervisor(s): E. Roberts Wood. Includes bibliographical references (p. 81). Also available online.
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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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Vasilescu, Roxana. "Helicopter blade tip vortex modifications in hover using piezoelectrically modulated blowing." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-11192004-165246/unrestricted/vasilescu%5Froxana%5F200412%5Fphd.pdf.
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Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2005.Dancila, Stefan, Committee Chair ; Sankar, Lakshmi, Committee Member ; Ruzzene, Massimo, Committee Member ; Smith, Marilyn, Committee Member ; Yu, Yung, Committee Member. Vita. Includes bibliographical references.
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Junas, Milan. "Předběžný návrh malého dvoumístného vrtulníku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241915.
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The thesis deals the preliminary draft of the small two-seat helicopter with a piston engine. The aim of the thesis is not to propose a helicopter across the extent of the problems. Therefore we have chosen only selected issues which can be managed in the range of work. The introduction is focused on defining the general requirements imposed on proposed helicopter, formulating the basic conceptual and structural design according to the building regulation the relevant category. These ranges create a based assumption for right evaluation of the statistical analysis of the helicopters of the same or very near parameters category. Subsequently, there were defined the basic parameters of the proposed helicopter which make possible to solve the performance characteristics in the vertical and backward flight. The work is also focused on design of the rotor head of main rotor for the proposed helicopter, the definition of load acting on the rotor head, waving analysis and calculation of centrifugal forces acting on the main rotor blades. The design of the rotor head and also the helicopter as a whole will be graphically processed in the program Dassault Systemes Catia.
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Uddin, Md Mosleh. "Active Vibration Control of Helicopter Rotor Blade by Using a Linear Quadratic Regulator." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2499.
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Active vibration control is a widely implemented method for the helicopter vibration control. Due to the significant progress in microelectronics, this technique outperforms the traditional passive control technique due to weight penalty and lack of adaptability for the changing flight conditions. In this thesis, an optimal controller is designed to attenuate the rotor blade vibration. The mathematical model of the triply coupled vibration of the rotating cantilever beam is used to develop the state-space model of an isolated rotor blade. The required natural frequencies are determined by the modified Galerkin method and only the principal aerodynamic forces acting on the structure are considered to obtain the elements of the input matrix. A linear quadratic regulator is designed to achieve the vibration reduction at the optimum level and the controller is tuned for the hovering and forward flight with different advance ratios.
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Rodriguez, Christian. "CFD Analysis on the Main-Rotor Blade ofa Scale Helicopter Model using Overset Meshing." Thesis, KTH, Farkost och flyg, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118797.
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In this paper, an analysis in computational uid dynamics (CFD) is presented on a helicopter scale model with focus on the main-rotor blades.The helicopter model is encapsulated in a background region and the ow eld is solved using Star CCM+. A surface and volume mesh continuum was generated that contained approximately seven million polyhedral cells, where the Finite Volume Method (FVM) was chosen as a discretization technique. Each blade was assigned to an overset region making it possible to rotate and add a cyclic pitch motion. Boundary information was exchanged between the overset and background mesh using a weighted interpolation method between cells. An implicit unsteady ow solver, with an ideal gas and a SST (Mentar) K-Omega turbulence model were used. Hover and forward cases were examined. Forward ight cases were done by changing the rotor shaft angle of attacks and the collective pitch angle 0 at the helicopter freestream Mach number of M = 0:128, without the inclusion of a cyclic pitch motion. An additional ight case with cyclic pitch motion was examined at s = 0 and = 0. Each simulation took roughly 48 hours with a total of 96 parallel cores to compute. Experimental data were taken from an existing NASA report for comparison of the results. Hover ight coincided well with the wind tunnel data. The forward ight cases (with no cyclic motion) produced lift matching the experimental data, but had diculties in producing a forward thrust. Moments in roll and pitch started to emerge. By adding a cyclic pitch successfully removed the pitch and roll moments. In conclusion this shows that applying overset meshes as a way to analyze the main-rotor blades using CFD does work. Adding a cyclic pitch motion at 0 = 5 and s = 0 successfully removed the roll and pitching moment from the results.
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Gill, Jason W. "The design of a rotor blade test facility." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4203.
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Thesis (M.S.)--West Virginia University, 2005.Title from document title page. Document formatted into pages; contains viii, 93 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 80-81).
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Huh, Kevin S. (Kevin Sangmin). "Helicopter rotor blade loading calculations using an axisymmetric vortex sheet and the free wake method." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/34028.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1988.Title as it appeared in M.I.T. Graduate List, Sept. 1987: Calculations of helicopter blade loading using an axisymmetric vortex sheet and free wake method.
Bibliography: leaves 75-77.
by Kevin Huh.
M.S.
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Pawar, Prashant M. "Structural Health Monitoring Of Composite Helicopter Rotor Blades." Thesis, Indian Institute of Science, 2006. http://hdl.handle.net/2005/273.
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Helicopter rotor system operates in a highly dynamic and unsteady aerodynamic environment leading to severe vibratory loads on the rotor system. Repeated exposure to these severe loading conditions can induce damage in the composite rotor blade which may lead to a catastrophic failure. Therefore, an interest in the structural health monitoring (SHM) of the composite rotor blades has grown markedly in recent years. Two important issues are addressed in this thesis; (1) structural modeling and aeroelastic analysis of the damaged rotor blade and (2) development of a model based rotor health monitoring system. The effect of matrix cracking, the first failure mode in composites, is studied in detail for a circular section beam, box-beam and two-cell airfoil section beam. Later, the effects of further progressive damages such as debonding/delamination and fiber breakage are considered for a two-cell airfoil section beam representing a stiff-inplane helicopter rotor blade. It is found that the stiffness decreases rapidly in the initial phase of matrix cracking but becomes almost constant later as matrix crack saturation is reached. Due to matrix cracking, the bending and torsion stiffness losses at the point of matrix crack saturation are about 6-12 percent and about 25-30 percent, respectively. Due to debonding/delamination, the bending and torsion stiffness losses are about 6-8 percent and about 40-45 percent after matrix crack saturation, respectively. The stiffness loss due to fiber breakage is very rapid and leads to the final failure of the blade. An aeroelastic analysis is performed for the damaged composite rotor in forward flight and the numerically simulated results are used to develop an online health monitoring system. For fault detection, the variations in rotating frequencies, tip bending and torsion response, blade root loads and strains along the blade due to damage are investigated. It is found that peak-to-peak values of blade response and loads provide a good global damage indicator and result in considerable data reduction. Also, the shear strain is a useful indicator to predict local damage. The structural health monitoring system is developed using the physics based models to detect and locate damage from simulated noisy rotor system data. A genetic fuzzy system (GFS) developed for solving the inverse problem of detecting damage from noise contaminated measurements by hybridizing the best features of fuzzy logic and genetic algorithms. Using the changes in structural measurements between the damaged and undamaged blade, a fuzzy system is generated and the rule-base and membership functions optimized by genetic algorithm. The GFS is demonstrated using frequency and mode shape based measurements for various beam type structures such as uniform cantilever beam, tapered beam and non-rotating helicopter blade. The GFS is further demonstrated for predicting the internal state of the composite structures using an example of a composite hollow circular beam with matrix cracking damage mode. Finally, the GFS is applied for online SHM of a rotor in forward flight. It is found that the GFS shows excellent robustness with noisy data, missing measurements and degrades gradually in the presence of faulty sensors/measurements. Furthermore, the GFS can be developed in an automated manner resulting in an optimal solution to the inverse problem of SHM. Finally, the stiffness degradation of the composite rotor blade is correlated to the life consumption of the rotor blade and issues related to damage prognosis are addressed.
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Andersch, Philipp [Verfasser]. "On the Modeling and Analysis of Helicopter Rotor Dynamics for a Frictional Blade Attachment / Philipp Andersch." München : Verlag Dr. Hut, 2017. http://d-nb.info/1139539507/34.
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Higman, Jerry Paul. "On the indentification of harmonic loads and inflow of a coupled bending-torsion helicopter rotor blade." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/12529.
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Bellocchio, Andrew Thomas. "Drive System Design Methodology for a Single Main Rotor Helicopter." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7524.
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The transformation of Joint forces to be lighter, more lethal, and capable of deploying from multiple dispersed locations free of prepared landing zones requires a dedicated heavy lift VTOL aircraft capable of rapidly delivering large payloads, such as the 20 to 26 ton Future Combat System, at extended ranges in demanding terrain and environmental conditions.
Current estimates for a single main rotor configuration place the design weight over 130,000 pounds with an installed power of approximately 30,000 horsepower. Helicopter drive systems capable of delivering torque of this magnitude succeeded in the Russian Mi-26 helicopters split-torque design and the Boeing VERTOL Heavy Lift Helicopter (HLH) prototypes traditional multi-stage planetary design. The square-cube law and historical trends show that the transmission stage weight varies approximately as the two-thirds power of torque; hence, as the size and weight of the vehicle grows, the transmissions weight becomes an ever-increasing portion of total gross weight. At this scale, optimal gearbox configuration and component design holds great potential to save significant weight and reduce the required installed power.
The drive system design methodology creates a set of integrated tools to estimate system weight and rapidly model the preliminary design of drives system components. Tools are provided for gearbox weight estimation and efficiency, gearing, shafting, and cooling. Within the same architecture, the designer may add similar tools to model subcomponents such as support bearings, gearbox housing, freewheeling units, and rotor brakes.
Measuring the relationships between key design variables and system performance metrics reveals insight into the performance and behavior of a heavy lift drive system. A parametric study of select design variables is accomplished through an intelligent Design of Experiments that utilizes Response Surface Methodology to build a multivariate regression weight model. The model permits visualization of the design space and assists in optimization of the drive system preliminary design.
This methodology is applied to both the Boeing HLH and the Russian Mi-26 main gearboxes. This study applies the drive system design methodology to compare the Mi-26 split-torque gearbox over the Boeing HLH multi-stage planetary gearbox in a single main rotor heavy lift helicopter.
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Sauter, Gregory P. "Durability modeling and design of a helicopter rotor Tie Bar." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA306021.
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Tzianetopoulou, Theodora 1974. "Design of an improved piezoelectric actuator for helicopter rotor control." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/82197.
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Ozgur, Cumhur. "Three-dimensional Design And Analysis Of A Compressor Rotor Blade." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606389/index.pdf.
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Three-dimensional design and three-dimensional CFD analysis of a compressor rotor stage are performed. The design methodology followed is based on a mean line analysis and a radial equilibrium phase. The radial equilibrium is established at a selected number of radii. NACA 65 series airfoils are selected and stacked according to the experimental data available. The CFD methodology applied is based on a three-dimensional, finite difference, compressible flow Euler solver that includes the source terms belonging to rotational motion. The accuracy of the solver is shown by making use of two different test cases. The CFD solution of the designed geometry predicts the static pressure rises and flow turning angles to a good degree of accuracy.
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Roth, Brian D. "Acoustic source and data acquisition system for a helicopter rotor blade-vortex interaction (BVI) noise reduction experiment." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA326229.
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Thesis (M.S. in Engineering Acoustics) Naval Postgraduate School, December 1996."December 1996." Thesis advisor(s): Robert M. Keolian, Steven R. Baker. Includes bibliographical references (p. 59). Also available online.
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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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Mostafa, A. "A design study for a compound helicopter featured with a convertible prop/rotor." Thesis, Cranfield University, 1989. http://dspace.lib.cranfield.ac.uk/handle/1826/11049.
Full textAbstract:
A compound helicopter is a hybrid vehicle, fundamentally a
helicopter. It uses an auxiliary lift and propulsion
device(s) in order to eliminate the lifting rotor high speed
limitation of retreating blade stall effects, thus allowing
flight characteristics comparable in many respects to those
of fixed-wing aircraft.
The primary objective of this thesis was to perform a design
study investigating the validity of the concept of
compounding, then selecting and designing a shaft-driven
single compound helicopter intended for use as a ground
support and anti-tank VTOL aircraft. The selection included
a complete parametric and sizing analysis which were based
on three defined maj or mission requirements: a maximum
forward speed of 250 knots; payload of 1500 lb and cruising
endurance of 3 hours at 225 knots.
Of the many configurations studied, a single-rotor compound
helicopter featured with convertible tail prop/rotor was
found to be the most suitable for the intended application.
Stability/control characteristics and performance capability
of the designed aircraft were found to meet or exceed
military specifications and flying quality requirements.
structure, dynamics and cost analysis were considered to be
beyond the scope of the design study.
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Johansson, Helena. "Investigation of rotor downwash effects using CFD." Thesis, Linköping University, Department of Electrical Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17651.
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This paper is the result of a master thesis project on helicopter rotor downwash effects using computational fluid dynamics (CFD). The work was performed at the department of Aerodynamics and Flight Mechanics at Saab AB, Linköping in 2008. It completes the author’s studies for a M.Sc degree in Applied Physics and Electrical Engineering at the Department of Electrical Engineering at the Linköping institute of technology (LiTH), Linköping, Sweden.
The aim of the project was to study the rotor downwash effects and its influence on the helicopter fuselage. To fulfil this purpose, several CFD calculations were carried out and the aerodynamic forces and moments resulting from the calculations were implemented in an existing simulation model, developed in-house at Saab. The original (existing) model was compared to the updated model by studying step responses in MATLAB, Simulink. For some step commands, the comparisions indicated that the updated model was more damped in yaw compared to the original model for the hovering helicopter. When the helicopter was trimmed for a steady turn, the states in the updated model diverged much faster than the states in the original model for any given step command.
In order to investigate the differences between the original helicopter model and the updated model from a controlling perspective, a linear quadratic (LQ) state feedback controller was synthesized to stabilize the vehicle in a steady turn. The LQ method was chosen as it is a modern design technique with good robustness and sensitivity properties and since it is easily implemented in MATLAB. Before synthesising, a simplification of the helicopter model was made by reducing states and splitting them into lateral and longitudinal ones. Step responses from simulations with the original and the updated model were studied, showing an almost identical behavior.
It can be concluded that the aerodynamic coefficients obtained from the CFD calculations can be used for determining the aerodynamic characteristics of the helicopter. Some further validation is needed though, for example by comparing the results with flight test data. In order to build an aerodynamic data base that covers the whole flight envelop, additional CFD calculations are required.
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Visweswaraiah, Swaroop. "Structural design and multi-objective optimization of an advanced composite rotor blade." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97179.
Full textAbstract:
Advanced composite materials provide a wide range of design freedom by virtue of their anisotropy. For the structural design and optimization of an advanced composite rotor blade, computationally efficient analytical models that can simulate the behaviour of the blade are necessary. A reliable and computationally efficient in-house cross-sectional analysis code has been developed for applications in the preliminary analysis and structural optimization of composite rotor blades. Parametric studies emphasizing the influence of the changes made to the internal structure of the blade are presented to illustrate the variation of the elastic stiffnesses and the coupling stiffness terms as a function of the internal geometry changes. Box-beam and D-spars that are the idealizations of a composite airfoil structure are considered in this work. The variation of the elastic stiffnesses for the actual blade structure with NACA0015 (symmetrical airfoil) and NACA23015 (cambered airfoil) profiles have been accomplished. The internal geometry changes considered include: the web inclination angle of the spar and the web distance from the leading edge. A discussion on the effect of these changes on the actual and idealized structures has been reported. In addition, multi-objective optimization of the cross-sectional design of a helicopter rotor blade with NACA0015 profile has been performed using the min-max approach. The optimization problem has been formulated as target vector optimization while considering the internal geometry variables of the blade. Particle swarm optimization, a multi-agent direct search algorithm, has been selected for the optimization due to its efficacy in dealing with composite optimization problems. A comparison of the optimization results with/without the inclusion of the internal geometry variables has been reported to highlight the role that the internal geometry variables play in the structural design of composite rotor blades.Keywords: Advanced composite rotor blades, Elastic tailoring, Multi-objective optimization, Target vector optimization, Particle swarm optimization.Grâce à leurs propriétés anisotropiques, les matériaux composites avancés présentent une grande liberté en termes de conception et design. Afin de concevoir et optimiser une pale principale en matériaux composites avancés, des modèles analytiques pouvant simuler le comportement de la pale sont nécessaires. Un code mathématique fiable and efficace, en terme de puissance de calcul, a été développé pour faire des analyses préliminaires d'optimisation structurelle de pales principales en composite. Des études paramétriques, démontrant l'influence des changements faits à la structure interne de la pale, sont présentées pour illustrer la variation des modules de rigidité et des termes de couplage de rigidité en fonction de la géométrie interne de la pale.Un caisson et un longeron, qui sont une idéalisation d'un profil aérodynamique en composite, ont été considéré dans ce travail. La variation des modules élastiques de rigidité pour des structures de pales symétriques NACA0015 et cambrées NACA23015 a été déterminée. Les changements de géométrie interne considérés inclus : l'angle d'inclinaison de l'âme du longeron et la distance entre l'âme et le bord d'attaque. Une discussion sur l'effet de ces changements sur les structures réelles et idéalisées est présentée.De plus, une optimisation à objectifs multiples du design de la section transversale d'une pale d'hélicoptère avec un profil NACA0015 a été accomplie avec une approche min-max. Le problème d'optimisation a été formulé en tant qu'une optimisation à vecteur cible tout en considérant les variables géométriques internes de la pale. Une optimisation à essaim de particules, un algorithme de recherche direct à cibles multiples, a été sélectionnée pour l'optimisation à cause de son efficacité à gérer les problèmes d'optimisation avec les composites. Une comparaison des résultats d'optimisation incluant ou non les variables de géométrie internes a été reportée pour souligner le rôle que celles-ci jouent dans la conception structurelle des pales en composite.
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Perry, Dylan R. "AERODYNAMIC DESIGN AND STRUCTURAL ANALYSIS PROCEDURE FOR SMALL HORIZONTAL-AXIS WIND TURBINE ROTOR BLADE." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1375.
Full textAbstract:
This project accomplished two correlated goals of designing a new rotor blade to be used with the Cal Poly Wind Power Research Center, as well as defining the methodology required for the aerodynamic analysis of an optimized blade, the procedure required for generation of an accurate CAD model for the new blade geometry, and structural integrity verification procedure for the new blade via finite element analysis under several operating scenarios. The new rotor blades were designed to perform at peak efficiency at a much lower wind speed than the current CPWPRC rotor blades and incorporated a FEA verification process which was not performed on the earlier rotor blade design.
Since the wind characteristics relative to the location of the CPWPRC are essentially unchanging the most viable option, in regards to generating power for longer periods of time, is to redesign the HAWT rotor to capture more of the wind energy available. To achieve this, the swept area of the rotor was increased, suitable airfoils were utilized, and the new rotor blades were optimized to maximize their performance under the CPWPRC location’s wind conditions.
With an increased magnitude of wind energy being captured the aerodynamic loading on the rotor blades simultaneously increased which necessitated a structural analysis step to be implemented, both with classical hand calculations and with the assistance of an adequate FEA program, to ensure the new rotor blades did not fail under normal or extreme wind conditions. With the completion of this project the new rotor blade designed and analyzed in this report may be finalized and refined in order to be incorporated into the CPWPRC system in the future or the methodology defined throughout this project may be used to design an entirely different aerodynamically optimized rotor blade, including a CAD model and FEA structural integrity verification, as well.
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Jia, H.-X., G. Xi, L. Müller, R. Mailach, and K. Vogeler. "Effect of clocking on unsteady rotor blade loading in a low-speed axial compressor at design and off-design operating conditions." Sage, 2008. https://publish.fid-move.qucosa.de/id/qucosa%3A38439.
Full textAbstract:
This paper presents the results of stator clocking investigations at a design point and an operating point near the stability limit in a low-speed research compressor (LSRC). The unsteady flow field of the LSRC at several clocking configurations was investigated using a three-dimensional unsteady, viscous solver. The unsteady pressure on the rotor blades at midspan (MS) was measured using time-resolving piezoresistive miniature pressure transducers. The effect of clocking on the unsteady pressure fluctuation at MS on the rotor blades is discussed for different operating points. Based on the unsteady profile pressures, the blade pressure forces were calculated. The peak-to-peak amplitudes of the unsteady blade pressure forces are presented and analysed for different clocking positions at both the design point and the operating point near the stability limit of the compressor.
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Fowler, Leslie Paige. "Application of the Filtered-X LMS Algorithm for Disturbance Rejection in Time-Periodic Systems." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/36768.
Full textAbstract:
Extensive disturbance rejection methods have been established for time-invariant systems. However, the development of these techniques has not focused on application to time-periodic systems in particular until recently. The filtered-X LMS algorithm is regarded as the best disturbance rejection technique for aperiodic systems by many, as has been proven in the acoustics industry for rejecting unwanted noise. Since this is essentially a feedforward approach, we might expect its performance to be good with respect to time-periodic systems in which the disturbance frequency is already known. The work presented in this thesis is an investigation of the performance of the filtered-X LMS algorithm for disturbance rejection in time-periodic systems. Two cases are examined: a generalized linear, time-periodic system and the helicopter rotor blade in forward flight.
Results for the generalized system show that the filtered-X LMS algorithm does converge for time-periodic disturbance inputs and can produce very small errors. For the helicopter rotor blade system the algorithm is shown to produce very small errors, with a 96%, or 14 dB, reduction in error from the open-loop system. The filtered-X LMS disturbance rejection technique is shown to provide a successful means of rejecting timeperiodic disturbances for time-periodic systems.Master of Science
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Elfarra, Monier A. K. "Horizontal Axis Wind Turbine Rotor Blade: Winglet And Twist Aerodynamic Design And Optimization Using Cfd." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612987/index.pdf.
Full textAbstract:
The main purpose of this study is to aerodynamically design and optimize winglet, twist angle distribution and pitch angle for a wind turbine blade using CFD to produce more power. The RANS solver of Numeca Fine/Turbo was validated by two test cases, the NREL II and NREL VI blades. The results have shown a
considerable agreement with measurements for both cases. Two different preconditioners have been implemented for the low Mach number flow. The results have shown the superiority of Merkle preconditioner over Hakimi one and Merkle
was selected for further simulations. In addition to that, different turbulence models have been compared and the Launder &ndashSharma has shown the best agreement with measurements. Launder &ndash
Sharma was chosen for further simulations and for the design process. Before starting the design and optimization, different winglet configurations were studied. The winglets pointing towards the suction side of the blade have yielded higher power output. Genetic algorithm and artificial neural network were implemented in the design and optimization process. The optimized winglet has shown an increase in power of about 9.5 % where the optimized twist has yielded to an increase of 4%. Then the stall regulated blade has been converted into pitch regulated blade to yield more power output. The final design was produced by a combination of the optimized winglet, optimized twist andbest pitch angle for every wind speed. The final design has shown an increase in power output of about 38%.
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Jami, Valentina. "Development of Computer Program for Wind Resource Assessment, Rotor Design and Rotor Performance." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1513703072278665.
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Richards, Phillip W. "Design strategies for rotorcraft blades and HALE aircraft wings applied to damage tolerant wind turbine blade design." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53488.
Full textAbstract:
Offshore wind power production is an attractive clean energy option, but the difficulty of access can lead to expensive and rare opportunities for maintenance. Smart loads management (controls) are investigated for their potential to increase the fatigue life of damaged offshore wind turbine rotor blades. This study will consider two commonly encountered damage types for wind turbine blades, the trailing edge disbond (bond line failure) and shear web disbond, and show how 3D finite element modeling can be used to quantify the effect of operations and control strategies designed to extend the fatigue life of damaged blades.
Modern wind turbine blades are advanced composite structures, and blade optimization problems can be complex with many structural design variables and a wide variety of aeroelastic design requirements. The multi-level design method is an aeroelastic structural design technique for beam-like structures in which the general design problem is divided into a 1D beam optimization and a 2D section optimization. As a demonstration of aeroelastic design, the multi-level design method is demonstrated for the internal structural design of a modern composite rotor blade. Aeroelastic design involves optimization of system geometry features as well as internal features, and this is demonstrated in the design of a flying wing aircraft. Control methods such as feedback control also have the capability alleviate aeroelastic design requirements and this is also demonstrated in the flying wing aircraft example.
In the case of damaged wind turbine blades, load mitigation control strategies have the potential to mitigate the effects of damage, and allow partial operation to avoid shutdown. The load mitigation strategies will be demonstrated for a representative state-of-the-art wind turbine (126m rotor diameter). An economic incentive will be provided for the proposed operations strategies, in terms of weighing the cost and risk of implementation against the benefits of increased revenue due to operation of damaged turbines. The industry trend in wind turbine design is moving towards very large blades, causing the basic design criterion to change as aeroelastic effects become more important. An ongoing 100 m blade (205 m rotor diameter) design effort intends to investigate these design challenges. As a part of that effort, this thesis will investigate damage tolerant design strategies to ensure next-generation blades are more reliable.
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Muppana, Sai. "Multi-fidelity Design and Analysis of Single Hub Multi-rotor High Pressure Centrifugal Compressor." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553517075653458.
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Steyn, J. (Johannes). "Design, manufacture and test of a bearingless rotor hub for the 24% scale model of the Rooivalk attack helicopter." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51676.
Full textAbstract:
Thesis (MEng) -- Stellenbosch University, 2000.Some digitised pages may appear illegible due to the condition of the original hard copy.
ENGLISH ABSTRACT: This document contains the work done on the bearingless rotor hub for the 24% scale model of the Rooivalk Attack Helicopter situated at the CSIR in Pretoria. This work forms part of the MSc Ing degree of Johannes Steyn. This work was deemed necessary because of a movement away from the fully articulated rotor to one of hingeless and more recently bearingless rotors. The main emphasis of this thesis is to be a technology demonstrator more than the design of a fully working bearingless rotor hub. With this in mind the final design in this report is not an optimal one, but the procedures and methodology in getting to a design are laid out in this document. To verify the design, tests were identified and created. The procedures for these tests are also included in this document. For the fatigue test a test bench had to be designed and built. This document also includes the design of this test bench
AFRIKAANSE OPSOMMING: Die dokument lewer verslag van die aktiwiteite vir die ontwerp van ‘n laerlose rotor van die 24% skaal model van die Rooivalk Helikopter, gelee by die WNNR in Pretoria. Die werk gedoen vorm deel van die MSc Ing graad van Johannes Steyn. Die werk is nodig geag omdat daar ‘n tendens is om weg te beweeg van die volledig geartikuleerde rotor na die van ‘n skanierlose en meer huidig ‘n laerlose rotor. Die hoof klem van die tesis is om as tegnologie demonstrator op te tree, eerder as die daarstel van ‘n werkende laerlose rotor. Na aanleiding van bogenoemde stelling kan die finale ontwerp nie as optimaal beskou word nie. Die prosedures en metodiek wat gevolg is om die ontwerp te kry word uitgele in die dokument. Om die ontwerp te verifieer is toetse gei'dentifiseer. Die prosedures vir elk van die toetse word ook in die dokument ingesluit. Vir die uitputtingstoetse moes ‘n spesiale toetsbank ontwerp en gebou word. Die ontwerp van hierdie toetsbank is ook in die dokument.
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Li, Leihong. "Structural design of composite rotor blades with consideration of manufacturability, durability, and manufacturing uncertainties." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24757.
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Thesis (Ph.D.)--Aerospace Engineering, Georgia Institute of Technology, 2009.Committee Chair: Hodges, Dewey H.; Committee Member: Bauchau, Olivier A.; Committee Member: Johnson, Ellis; Committee Member: Makeev, Andrew; Committee Member: Volovoi, Vitali V.
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Polat, Ozge. "Genetic Algorithm Based Aerodynamic Shape Optimization Of Wind Turbine Rotor Blades Using A 2 D Panel Method With A Boundary Layer Solver." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613970/index.pdf.
Full textAbstract:
This thesis presents an aerodynamic shape optimization methodology for rotor blades of horizontal
axis wind turbines. Genetic Algorithm and Blade Element Momentum Theory are implemented
in order to find maximum power production at a specific wind speed, rotor speed
and rotor diameter. The potential flow solver, XFOIL, provides viscous aerodynamic data of
the airfoils. Optimization variables are selected as the sectional chord length, the sectional
twist and the blade profiles at root, mid and tip regions of the blade. The blade sections are
defined by the NACA four digit airfoil series or arbitrary airfoil profiles defined by a Bezier
curve. Firstly, validation studies are performed with the airfoils and the wind turbines having
experimental data. Then, optimization studies are performed on the existing wind turbines.
Finally, design optimization applications are carried out for a 1 MWwind turbine.
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Brown, Jeffrey M. "Reduced Order Modeling Methods for Turbomachinery Design." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1229962254.
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Chakravarty, Uttam Kumar. "Section builder: a finite element tool for analysis and design of composite." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22640.
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Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2008.Committee Chair: Bauchau, Olivier; Committee Member: Craig, James; Committee Member: Hodges, Dewey; Committee Member: Mahfuz, Hassan; Committee Member: Volovoi, Vitali.
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Flores, Colunga Gerardo Ramón. "Design, modeling and control of a convertible mini airplane having four tiliting rotors." Thesis, Compiègne, 2014. http://www.theses.fr/2014COMP2095/document.
Full textAbstract:
Cette thèse étudie certains problèmes plus importants dans le sens de guidage, navigation et contrôle présentés dans une catégorie particulière de mini véhicules aériens (MVA) : le MVA convertible avec des ailes fixes et disques pendulaires. Cet aéronef est capable de changer sa configuration de vol, du vol stationnaire au vol palier et vice versa, au moyen d’une manœuvre de transition. Motivé par des applications civiles, on étudie théoriquement et expérimentalement les principes de contrôle en fonction de Lyapunov pour les dynamiques présentées dans le MVA convertible. Des résultats de convergence asymptotique sont obtenus sur l’enveloppe de vol complet du véhicule : d’un vol vertical à basse vitesse à un vol vers l’avant à grande vitesse. Cette thèse est divisée en quatre parties principales : l’étude de 1) les aéronefs à voilure fixe ; 2) le quadrirotor (avion équipe de quatre moteurs) ; 3) l’aéronef convertible ; 4) les applications de vision en utilisant l’aéronef convertible. Dans la première partie, un principe de contrôle en fonction de Lyapunov est développé pour diriger un mini véhicule aérien à voilure fixe tout au long d’un chemin d’accès souhaité. En outre, un générateur de chemin d’accès est proposé. Le résultant de la stratégie du contrôle donne une convergence globale du chemin actuel du MVA au chemin d’accès souhaité. Dans la deuxième partie, un contrôle en fonction de Lyapunov à l’aide de la théorie de la perturbation du singulier est proposé et appliqué sur la dynamique du MVA. En effet, dans cette partie on a abordé le problème diagnostic et la détection de pannes fault detection and diagnosis (FDD) pour un quadrirotor. Dans la troisième partie une nouvelle stratégie de contrôle pour effectuer la transition d’un avion convertible entre le mode avion et le mode hélicoptère, et vice versa, est présenté. L’analyse est effectuée pour le modèle longitudinal du PVHAT (Planar Vertical Helicopter-Airplane Transition) aéronef, lequel est un avion ayant disques pendulaires afin de réaliser la manœuvre de transition. L’algorithme de contrôle de boucle fermée qui en résulte, est prouvé être globalement asymptotiquement stable. Finalement, dans la quatrième partie de cette thèse, le problème de l’estimation et suivi d’un chemin à l’aide de vision système embarqué dans l’avion PVHAT est résolu. La stabilité globale exponentielle de la position sous-système ainsi que le contrôleur de commutation est démontrée. Des simulations illustratives et résultats expérimentaux sont obtenus sur plusieurs plateformes expérimentales développées dans cette thèse, pour évaluer l’applicabilité des principes contrôle proposés et mettre en valeur les mérites de l’approcheThis thesis studies some of the most relevant problems in the sense of guidance,navigation and control presented in a particular class of mini aerial vehicles (MAV) : the convertible MAV with fixed wings and tilting rotors. This aircraft is able to change its flight configuration from hover to level flight and vice-versaby means of a transition maneuver. Motivated by civilian applications, we theoretically and experimentally study Lyapunov-based control laws for dynamics presented in the convertible MAV. Results of asymptotic convergence are obtained over the complete flight envelope of the vehicle : from low-speed vertical flight through high-speed forward flight. We have divided this thesis in four main parts : the study of 1) the fixed-wingaircraft; 2) the quadrotor; 3) the convertible aircraft and 4) vision applications by using the convertible aircraft. In a first part, a Lyapunov-based controllaw is developed to steer a fixed wing mini aerial vehicle along a desired path. Furthermore a path generator is proposed. The resulting control strategy yields global convergence of the current path of the MAV to the desired path. In a second part, a Lyapunov-based control using singular perturbation theory is proposed and applied on dynamics of the MAV. Furthermore, in this part we address the problem of fault detection and diagnosis (FDD) for a quad-rotor. In the third part a new control strategy for the transition between airplane and helicopter mode, and vice versa, in convertible planes is presented. The analysis is carried out for the longitudinal model of the PVHAT (Planar VerticalHelicopter-Airplane Transition) aircraft, which is an airplane having tilting rotors in order to achieve the transition maneuver. The resulting closed loop control algorithm is proved to be globally asymptotically stable. Finally in thefourth part of this thesis the problem of estimation and tracking of a road using avision embedded system in the PVHAT aircraft is solved. The global exponential stability of the position subsystem together with the switching controller is demonstrated. Illustrative simulations and experimental results obtained on several experimental platforms developed in this thesis, assess the implementability of the proposed control laws and highlight the merits of the approach
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Duffy, Michael James. "Small wind turbines mounted to existing structures." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34765.
Full textAbstract:
Small wind turbines, and especially urban-mounted turbines which require no dedicated pole, have garnered great public enthusiasm in recent years. This enthusiasm has fueled widespread growth among energy conservationists, and estimates predict that the power produced nationally by small wind will increase thirty-fold by 2013. Unfortunately, most of the wind resources currently available have been designed for larger, rural-mounted turbines; thus, they are not well suited for this nascent market. A consequence of this is that many potential urban small wind turbine owners over-predict their local wind resource, which is both costly and inefficient. According to a recent study published by Encraft Ltd., small wind turbines mounted to buildings far underperformed their rural pole mounted counterparts.
As a proposed solution to this problem, this project introduces the concept of a Web-based Wind Assessment System (WWAS). This system combines all the necessary resources for potential urban small wind turbine customers into a single web-based tool. The system also presents the concept of a modular wind measurement system, which couples with the WWAS to provide real-time wind data measurements. The benefits of the system include its ease of use, flexibility of installation, data accessibility from any web browser, and expert advice. The WWAS prevents potential clients from investing in a system that may not be viable for their location.
In addition, a small wind turbine is designed in this project, which has a unique modular mounting system, allowing the same baseline wind turbine to attach to various structures using interchangeable mounting hardware. This includes such accessible urban structures as street lights, building corners, flag poles, and building walls, among others.
This design also utilizes concepts that address some of the challenges associated with mounting small wind turbines to existing urban structures. These concepts include: swept tip blades and lower RPM to reduce noise; vibration suppression using rubber shims; a netted duct to protect wildlife; and a direct-drive permanent magnet generator to ensure low starting torque.
Finally, the cost of this system is calculated using off-the-shelf components, which minimize testing and certification expense. This small wind turbine system is designed to be grid-connected, has a 6 foot diameter rotor, and is rated at 1 kW. This design features a unique modular interchangeable mounting system. The cost for this complete system is estimated to be $2,050. If a users' site has an average wind speed of 14 mph (6.5 m/s), this system will generate a return on investment in 8.5 years, leaving over 10 years of profit. The profit for this system, at this sample average wind speed, yields over $4,000 during its 20-year design life, which is a two-fold return on investment.
This project has implications for various stakeholders in the small wind turbine market, including designers, engineers, manufacturers, and potential customers. Equally important is its potential role in guiding our future national--even global--energy agenda.