Dissertations / Theses on the topic 'Rotor-blade system'

This research developed two innovative test methods that were used to experimentally evaluate the performance of a novel blade tip timing (BTT) system from Prime Photonics, LC. The research focused on creating known blade tip offsets and tip vibrations so that the results from a BTT system can be validated. The topic of validation is important to the BTT field as the results between many commercial systems still are not consistent. While the system that was tested is still in development and final validation is not complete, the blade tip offset and vibration frequency validation results show that this BTT system will be a valuable addition to turbomachinery research and development programs once completed. For the first test method custom rotors were created with specified blade tip offsets. For the blade tip offset alternate measurement, the rotors were optically scanned and analyzed in CAD software with a tip location uncertainty of 0.1 mm. The BTT system agreed with the scanned results to within 0.13 mm. Tests were also conducted to ensure that the BTT system identified and indexed the blades properly. The second developed test method used an instrumented piezoelectric blade to create known dynamic deflections. The active vibration rotor was able to create measureable deflection over a range of frequencies centered on the first bending mode of the blade. The results for the 110 Hz, 150 Hz, 180 Hz first bending resonance, 200 Hz, and 1036 Hz second bending resonance cases are presented. A strain gage and piezoelectric sensor were attached to the active blade during the dynamic deflection tests to provide an alternate method for determining blade vibration frequency. The BTT system correctly identified the active blade excitation frequencies as well as a 120 Hz frequency from the drive motor. This thesis also explored applying BTT methods and testing to more realistic blade geometry and vibration. Blade vibrations are usually classified by their frequency relative to the rotation speed. Synchronous vibrations are integer multiples of the rotational speed and are often excited by struts or vanes fixed to the engine case. For this reason, special probe placement algorithms were explored that use sine curve fitting to optimize the probe placement. Knowing how the blade will vibrate at operation before testing is critical as well. In preparation for future research, ANSYS Mechanical was used to predict the first three modes of a PT6A-28 first stage rotor blade at 1,966, 5,539, and 7,144 Hz. These frequencies were validated to within 4% using scanning laser vibrometry. The simulation was repeated at speed to produce a Campbell Diagram to highlight synchronous excitation crossings.
Master of Science

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.

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.

Le sujet d'étude est la réponse d’un système mécanique déterministe en rotation et soumis à des sollicitations stochastiques. Pour cela, un modèle mécano-probabiliste est développé, résultant de la combinaison de deux éléments : le système mécanique au comportement dit non-standard, et les sollicitations, représentées par un champ stochastique corrélé. L'application vise l'analyse fiabiliste d’une hydrolienne, décrite par un modèle mécanique d’ordre réduit. Plusieurs méthodes sont présentées, comparées et leurs limitations sont mises en évidence. Les résultats obtenus sont contrastés avec ceux de la bibliographie. En particulier, l’aspect innovant se trouve dans le type de quantité mécanique modélisée, le traitement et l'interprétation des quantités modales, et le type de processus stochastique considéré comme sollicitation. Plus précisément, le modèle dynamique développé décrit une classe de systèmes mécaniques de type rotor-pale. Il a été construit par une combinaison judicieuse de résultats des domaines de l'éolien, l'hydrolien, la dynamique des rotors et des vibrations mécaniques. La formulation lagrangienne de la mécanique analytique est utilisée pour obtenir les équations du système dynamique. L'assemblage obtenu avec des composants élastiques linéaires, introduits avec leur comportement modal, produit des termes instationnaires, résultant dans des équations différentielles ordinaires à coefficients périodiques. Pour l'analyse de ce problème mécanique déterministe, l’analyse modale numérique traditionnelle est ici étendue grâce à la théorie de Floquet. La réponse du système est formulée en termes des exposants caractéristiques du système et des vecteurs propres de Floquet, ou vecteurs propres périodiques, permettant une représentation modale de la matrice de transition de Floquet. Diverses méthodes peuvent alors être appliquées pour l'analyse modale du système et on propose une nouvelle méthode basée sur la représentation temps-fréquence grâce aux ondelettes périodiques généralisées. Pour considérer les sollicitations aléatoires instationnaires et non-gaussiennes, on utilise une écriture innovante pour la propagation des moments. L’avantage de cette technique vient de l’aspect pratique et systématique des développements, ce qui est particulièrement avantageux lorsqu'elle est appliquée à des champs spatio-temporels instationnaires. En combinant cette technique avec une méthode d’estimation de la densité de probabilité basée sur le principe d’entropie maximale, nous arrivons à l’estimation de la distribution des valeurs extrêmes de la réponse cherchée en considérant le problème de dépassement d’un seuil par ce processus instationnaire, permettant ainsi la résolution du problème posé en termes de fiabilité dépendante du temps
The response of a deterministic rotating mechanical system under stochastic excitation is studied. A mechanical-probabilistic model is developed to combine the relevant characteristics of both aspects of the study: the behavior of this non-standard class of mechanical system and the random properties of correlated stochastic fields describing load processes. The results are applied to a reliability analysis of a reduced order model of a tidal turbine. Semi-analytic and empirical ( in the Monte-Carlo simulation sense) results are obtained, compared and contrasted. The results are framed with respect to the existing literature, and it is found that they provide an innovative treatment of the problem, in terms of the dynamical choices reflected in the model, in the presentation and interpretation of the modal aspects of the system, and in the type of stochastic inputs considered. We develop a dynamical model describing a broad class of mechanical system that models a rotor-blade structure. The model is informed by careful consideration of previous results, with the aim of constructing a reduced model that captures essential characteristics of the vibratory behavior of the structure. Lagrangian formalism is utilized to obtain the equations of motion. The presence of elastic components, which are discretized in a modal way, results in a system of ordinary differential equations with periodic coefficients. The Floquet theory of Linear time-periodic systems is applied on the deterministic dynamical model to synthesize an extension of traditional modal analysis to systems with periodic coefficients. The response of the system is formulated in terms of Floquet exponents and the associated Floquet periodic eigenvectors, from which the Floquet State Transition Matrix can be obtained. Several methods are applied to the modal study of the system, and a new time-frequency approach is proposed based on PGHW wavelets and its associated scalogram. Using an innovative notation to describe probabilistic moments of stochastic quantities, a moment propagation scheme is presented and exploited. The advantages of the treatment, particularly in the case of spatio-temporal stochastic fields, is in its applicability and systematic structure of development. This moment propagation strategy is coupled with a maximum entropy formulation to reconstruct the probability density function of the response and obtain important descriptors of the response, such as the Extreme Value Distribution. The moment propagation technique presented is applied to nonstationary processes. The results from Modal Floquet theory are integrated into this analysis. The problem of crossings of a certain threshold is considered for this type of nonstationary stochastic process. Their response is shown to yield a time-dependent reliability problem, which is resolved using the estimated EVD and then by numerical simulation

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.

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.

A wind turbine needs to be controlled to ensure its safe and optimal operation, especially during high wind speeds. The most common control objectives are to limit the power and rotational speed of the wind turbine by using pitch control. Aero Energy is a company based in Potchefstroom, South Africa, that has been developing and manufacturing wind turbine blades since 2000. Their most popular product is the AE1kW blades. The blades have a tendency to over-speed in high wind speeds and the cut-in wind speed must be improved. The objective of this study was to develop an active pitch control system for wind turbines. A prototype active pitch control system had to be developed for the AE1kW blades. The objectives of the control system are to protect the wind turbine from over-speeding and to improve start-up performance. An accurate model was firstly developed to predict a wind turbine’s performance with active pitch control. The active pitch control was implemented by means of a two-stage centrifugal governor. The governor uses negative or stalling pitch control. The first linear stage uses a soft spring to provide improved start-up performance. The second non-linear stage uses a hard spring to provide over-speed protection. The governor was manufactured and then tested with the AE1kW blades. The governor achieved both the control objectives of over-speed protection and improved start-up performance. The models were validated by the results. It was established that the two-stage centrifugal governor concept can be implemented on any wind turbine, provided the blades and tower are strong enough to handle the thrust forces associated with negative pitch control. It was recommended that an active pitch control system be developed that uses positive pitching for the over-speed protection, which will eliminate the large thrust forces. Keywords: pitch control, wind turbine, centrifugal governor, over-speed protection, cut-in wind speed, blade element-momentum theory, rotor, generator, stall, feathering.
Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2009.

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

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.

The use of wind turbines offers a pollution-free, sustainable, and economically workable alternative to the provision of energy. Though substantial progress has already been made in the area of the wind industry, the performances of small wind harvesters can still be enhanced. It is essential to conduct additional research on the aerodynamics of wind turbines and their interaction with fluid flow. It is thus necessary to know various methods that can enhance the potential of a wind turbine. Over the last three decades, the size of the wind turbine blades has increased significantly. This growing size along with the associated mechanical behaviour, results in the generation of aeroelastic effects caused by the fluid-structure interaction (FSI). Effective FSI modelling of rotor blades is highly essential for the research of large-scale wind turbines. These large-scale wind turbines, on the other hand, are incapable of powering small devices, especially in remote locations where such small devices are used to monitor temperature, traffic, cyber security, etc. A small-scale energy harvester that can be used effectively in low-power devices must be investigated. Accommodating the aforementioned statements, this research work has implemented a numerical technique to enhance wind turbine output using different modifications and configurations. The fluid-structure interaction (FSI) analysis is also performed for wind turbine blades using composite materials. Furthermore, an attempt has been made to examine the functioning of a small lab-scaled wind turbine experimentally inside the wind tunnel. To execute these techniques, the fluent solver has been used with the help of the finite-volume method. In this work, four different types of airfoils were investigated, i.e., NREL (National Renewable Energy Laboratory) S809, S818, S825, and S826. Moreover, this work covers two configurations of a wind turbine: one the two-bladed turbine and the other the three-bladed turbine. For the two-bladed turbine NREL phase VI model has been considered to carry out the numerical investigation. For a three-bladed turbine, three kinds of the turbine have been designed and are listed below. 1) Design of the turbine by changing the two-bladed NREL phase VI to the three-bladed turbine. 2) Design of the turbine by using the dimension of GE 1.5 MW and considering S818 airfoil, S825 airfoil, and S826 airfoil. 3) Design of in-house laboratory-scale wind turbine by considering S818 airfoil, S825 airfoil, and S826 airfoil. An FSI simulation was performed for a blade by taking four composite materials in turns. CFD is used to compute the aerodynamic loads, whereas FEA is used to determine the blade structural reactions. The investigation was conducted using commercially available ANSYS packages. The performance of the turbine has been studied in terms of power, torque, deformation, and Von-Mises stress under varying conditions, and the most efficient conditions are outlined. Experiments on small-sized wind turbines have been executed inside the subsonic wind tunnel. Performance parameters are checked by varying wind speeds and loads. An electromechanical model has been developed. The results of the experiments have been compared with the electromechanical model. The experimental outcomes indicate that the designed wind turbine is capable of powering micro-devices.

碩士
淡江大學
機械工程研究所
83
The induced wake has a great effect on the stability of a helicopter rotor blades in hover and forward hlight. The research work in this paper is to study the interactions among induced wake and rotor blades. 　　This paper contains three parts:(1) the stability of induced wake and its mode shapes analysis. (2) the coupled system analysis of induced wake and rigid blades. (3) the coupled system analysis of induced wake and elastic blades. The Peters' Generalized Dynamic Inflow Theory with its accuracy and excellent characteristic in coupling is chosen as induced wakde theory. The merit of aeroelastic system coupled with rigid blades and elastic blades lies in it's a three-dimensional model and can be ulitized to predict the stability of a helicopter in different foward flight conditions. This aeroelastic system is etablished in a non-rotating system with which it containts periodic coefficients; thus, Floquet Theory is chosen to perform an eigen-analysis. 　　The results of this paper provide us an eigen-analysis among induced wake coupled with rigid blades and with elastic blades in aeroelastic system. In accordance with the results of this eigen-analysis, we realize that induced wake on rigid and elastic blades flapping damper somehow has an effect in hover and forward flight; especially, the effect in forward flight is much stronger. Above all, the research work in this paper can help to realize a helicopter flight conditions and also to motivate its futher research and design.

碩士
大同大學
工程管理碩士在職專班
103
The global aviation business is continuously developing. In response to operation readiness, disaster prevention, disaster relief, transportation and a variety of different mission requirements, the demand for helicopter maintenance is keeping increased, but the part failures highly affect flight stand missions. If we can create prediction systems for the helicopters’ critical parts failures, so as to perform maintenance before the failure occurs, and that system will help to reduce the rate of flight delays caused by unpredictable failures. The creation may serve as a reference for our Armed Forces to manage its maintenance and spare parts. This study takes the main rotor blade used on the helicopter Super Cobra attack helicopters as an example. At the beginning, it uses Delphi Method to prepare the first expert questionnaire to collect the key factors affecting the life of the main rotor blades. After that, the study uses Linker five-point scale to score the expert questionnaires,and, in accordance with experts consistency index, selects six important key factors such as temperature, humidity, the number of take offs and landings, sunshine, rainfall and the numbers of rainy days. Further, the data of main rotor blade maintenance performing during year 2012 to 2014 is used as samples to be loaded in to back-propagation neural network software(Neuro Intelligence)to test the relation ship between input and output to build predictive models. A set of parameters obtained from the test includes the numbers of neuron the hidden layer: 6, learning rate:0.2, and the times of learning cycles:2,000. The number set is used as Back-propagation network prediction criteria in order to predict the usage life of a main rotor blade after installation. After learning and training by the inverted neural network software, the relevance (Correlation) and mode of fit(R-squared) reaches 0.999386 and 0.998655, respectively, and the accuracy of prediction is as high as 97%, and that proves back-propagation neural network is indeed an effective method to predict the life of helicopter parts. Using back-propagation neural network to create prediction model, this study can help our Armed Forces or airlines to formulate strategies for the helicopter part sin advance, so as to complete repair and maintenance ahead of schedule and establish knowledge management and experience heritage for the maintenance.In the future, the model can be applied to different type sof weapons and equipment, in order to invest with the minimum of costs and resources, to reduce risk,manpower for maintenance, acquisition, and management to magnify the advantages.

碩士
國立臺北科技大學
機電整合研究所
95
In order to build an efficient electronic system for the Unmanned Aerial Vehicles, various sensors and actuators must be handled in a distributed way. A group of microprocessors will sense and process signals from individual sensors and transmit the data to the central controller through the communication protocol. The present paper has modified and improved a distributed UAV system with the CAN Bus communication protocol. Emergency Module, Main Rotor Speed Control Module and Ground Station Data Logging Module have been added in the UAV system to improve the system performance. The sensed data will be used to calculate the navigation path and be verified to demonstrate the feasibility and reliability of this avionic system. 　　 In order to simplify the flight control design of UAV, the main rotor will be controlled at fixed rotating speed. The loading of the UAV will be controlled by changing the main rotor pitch angle. The present research has applied fuzzy control to stabilize the main rotor speed. 　　Furthermore, the present paper has measured the damping ratio of UAV’s rotor blades in two degree-of-freedoms, flapping and feathering, so that the dynamic model of the UAV can be developed more thoroughly. Because rotor blades are the critical elements of helicopter, in order to monitor the reliability of the blades, this research has also defined an index to measure the structural damage of the rotor blade. With this index, the technician can easily determine whether and when the rotor blade should be replaced. This can prevent the UAV from accidents due to the unexpected failure of blade.

碩士
淡江大學
航空太空工程學系
87
Optimum design of two different design variables, chord length and twist angle, through an unsteady aerodynamic system will be considered in this study. Besides, this paper also discuss the coupling effect between chord length and twist angle, and apply wake dynamics, areodynamics and optimality criterion theory to obtain the optimum configuration of rotor blades. The purpose of this study is to obtain a helicopter blades' chord length and twist angle which to minimize the power output and also maintain the lift force in a misson. Because design variable doubles and couples so that the problem becomes complicated, an improve move limit with Bezier curve technique will be implemented in optimal program to overcome these effect. The BELL UH-1H helicopter rotor blades will be redesign by optimum design program exactly and steadily. The result of new design rotor blade will compare with the original rectangular rotor blade in numerical examples.