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Le crawl est actuellement la nage utilisée lors des épreuves de nage libre durant les compétitions de natation aux différentes allures de nage (sprint, demi-fond et fond). Les bras sont les segments corporels qui participent le plus à la propulsion. Les accélérations de ces segments, dans le milieu fluide au repos, génèrent un écoulement complexe qui est à l'origine des forces hydrodynamiques propulsives. L'analyse de cet écoulement est nécessaire pour en comprendre les principaux mécanismes. Dans ce cadre, des « paramètres cinématiques d'écoulement » (vitesse, accélération et orientation de la main, angles d'attaque et de sweepback) ont été définis afin d'analyser et comparer les différentes organisations gestuelles des nageurs et de leurs effets sur la propulsion. Deux des principaux axes d'investigation étaient de vérifier si ces paramètres variaient en fonction de l'allure, et aussi de déterminer quels paramètres cinématiques étaient les plus prépondérants dans la génération des mécanismes propulsifs. Pour cela, un système opto-électronique d'analyse cinématique, a permis de mesurer ces paramètres sur 17 nageurs experts. Par ailleurs, l'écoulement généré par le trajet des bras aux différentes allures a été simulé par résolution numérique instationnaire des équations de Navier-Stokes. Enfin, des mesures expérimentales d'effort ont été faites en nage attachée afin de connaître les forces propulsives.Il apparaît que l'augmentation de l'allure de nage peut davantage s'expliquer par la diminution des durées des phases non propulsives (entrée et allongement) plutôt que par l'augmentation des forces durant les phases les plus propulsives (balayages interne et externe). / Front crawl is a swimming stroke used at swimming competitions at freestyle different paces (sprint, middle distance and long distance). Propulsion in this stroke is achieved primarily by the forearm and hand. Accelerations of these segments, in a fluid at rest, generate complex flow that causes propulsive hydrodynamic forces. Analysis of this flow is necessary to understand the main mechanisms of propulsion. In this context, the "kinematic flow parameters" (velocity, acceleration and orientation of the hand, angles of attack and sweepback) have been defined to analyze and compare the different arm motions and their effects on propulsion. Two of the main axes of this investigation were to determine whether these parameters vary depending on the pace, and also to determine what kinematic parameters were most prominent in the generation of propulsive mechanisms. To this end, an optoelectronic system of motion capture was used to measure these parameters on 17 expert swimmers in free swimming. Furthermore, the flow generated by the experimentally acquired arm trajectory, at different swimming paces, was simulated by an unsteady numerical solution of the Navier-Stokes equations. Finally, tethered swimming experiments were carried out to measure the propulsive forces.The increase in forward velocity by increasing swimming pace can be explained by lower durations of non propulsive phases (entry and stretch) rather than by the generation of higher forces during the most propulsive phases (insweep and upsweep).

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / The National Aeronautics and Space Administration’s (NASA) Marshall Space Flight Center (MSFC) in Huntsville, Alabama will launch the Propulsive Small Expendable Deployer System (ProSEDS) space experiment in late 2000. ProSEDS will demonstrate the use of an electrodynamic tether propulsion system and will utilize a conducting wire tether to generate limited spacecraft power. This paper will provide an overview of the ProSEDS mission and will discuss the design, and test of the spacecraft telemetry system. The ProSEDS telemetry subsystem employs a combination of Commercial Off-The-Shelf (COTS) hardware and launch vehicle telemetry system components to minimize costs as well as power consumption. Several measures were used to aid the conservation of spacecraft power resources. First, the transmitter was modified to limit input power consumption to less that 20 watts while providing approximately two watts Radio Frequency (RF) output power. Secondly, the ProSEDS on board Global Positioning System (GPS) receiver is being used to control input power to the transmitter in order to limit the telemetry operations to occasions when the spacecraft is in proximity to preprogrammed ground station locations.

Un micro-drone à voilure tournante est l’appareil aérien optimal pour assister un rover d’exploration à lanavigation sur la planète Mars. Toutefois, les écoulements qu’il rencontre sont compressibles à très faiblenombre de Reynolds, ce qui constitue un domaine de l’aérodynamique inédit et quasiment inexploré à cejour. L’objectif de la thèse est de comprendre, simuler et recréer expérimentalement les phénomènes aérodynamiquesliés au régime inédit des écoulements martiens pour concevoir un système propulsif performant.Après avoir validé les outils de simulation numérique, le comportement instationnaire des écoulements estétudié sur des géométries 2D et 3D. L’écoulement est dominé par la viscosité : les couches limites laminairessont épaisses et le décollement a beaucoup d’influence sur son comportement très instationnaire.Par la suite, plusieurs millions de géométries de profil sont évaluées par un processus d’optimisation basésur un code 2D stationnaire. Les profils optimisés sont fortement cambrés (entre 5.5% et 7%) et de faibleépaisseur relative (e/c ∼ 2%). Le bord d’attaque et le bord de fuite sont très cambrés pour permettrerespectivement l’adaptation à l’écoulement incident et la fixation du point de décollement de la couchelimite. À partir des géométries de profils, l’ensemble du système propulsif est optimisé par intégration despolaires 2D. La théorie des éléments de pale permet de déterminer rapidement les configurations les plusperformantes aérodynamiquement. Et une méthode de sillage libre permet l’optimisation de rotors isoléset de systèmes propulsifs coaxiaux. Les rotors ont des solidités et des vrillages importants, ce qui rappelleles formes d’hélices marines. Les simulations Navier-Stokes 3D mettent en évidence la tridimensionnalitédes écoulements sur la pale, elle est fortement corrélée avec la solidité du rotor et le vrillage de bout depale. La rotation stabilise la couche limite et donne lieu à un décollement stable au bord d’attaque pourcertaines géométries. Le dévrillage en bout de pale permet de stabiliser le tourbillon et de diminuer la perteinduite. Un banc de mesure est placé dans un caisson dépressurisé pour estimer les efforts de poussée et decouple générés par les rotors optimisés en conditions aérodynamiques martiennes. Les essais permettentde valider les tendances d’estimation des codes de simulation ainsi que les processus d’optimisation. Laconfiguration bi-rotors coaxiaux, en comparaison avec une configuration à deux rotors adjacents, permetun gain d’encombrement de moitié pour une perte sur la puissance de seulement 15%. C’est la configurationla plus adaptée pour un micro-drone en atmosphère ténue. Un système propulsif coaxial optimisé (dediamètre 30 cm) permettrait de sustenter un micro-drone d’environ 400 grammes en conditions nominalessur la planète Mars. / A micro-rotorcraft is the most suited aerial vehicle for rover navigation assistance on Mars. The martianatmosphere’s density, being hundred times lower than on Earth, requires the micro-drone to hover at highrotational speed. Hence, flows on the blade are both compressible and at very low Reynolds number (fewthousands). It constitutes a new aerodynamic domain to be explored. The purpose of the dissertation isto understand, simulate and experimentally duplicate the aerodynamic phenomena in a view to design anefficient propulsion system. After a phase of validation of the simulation tools, the flows’ unsteady behavioris studied on 2D and 3D geometries. Wall flow is highly viscous : laminar boundary layers are thick andtheir separation has a huge influence on its unsteadiness. Then, several millions of airfoil geometries areevaluated by an optimization process based on a steady 2D solver. As final result, the optimized airfoildisplays a highly cambered shape (between 5.5% and 7%) with low relative thickness (t/c ∼ 2%). Leadingand trailing edges are strongly cambered, allowing proper incoming flow adaptation and late boundarylayer separation. Based on this airfoil geometry, rotor shapes are optimized by two methods. Blade elementtheory provides a quick investigation of the most aerodynamically efficient configurations. And a free wakesolver is applied for the final design of isolated rotors and coaxial dual-rotors. Optimized shapes exhibitimportant twist and solidity, evoking marine propellers. 3D Navier-Stokes simulations highlight the flow’sthree-dimensional mechanisms on the blade, which are highly correlated to the rotor’s solidity and twist.Rotation stabilizes the blade’s boundary layer and a stable leading edge separation is observed in somecases. Blade tip twist reduction diminishes the tip vortex and the induced loss. A thrust and torquemeasurement setup is placed in a depressurized tank for the evaluation of optimized rotors in martianatmospheric conditions. Performed experiments confirm the solvers’ trend and validate the design process.Therefore, chosen coaxial dual-rotors configuration provides an important size gain for a low correspondingpower loss (∼ 15%) compared to adjacent dual-rotors. Coaxial dual-rotors are the optimal configuration fora micro-rotorcraft in low-pressure atmosphere flight conditions. Such propulsion system (with a diameterof 30 cm) could lift a 400 grams micro-rotorcraft in hover on the planet Mars.

Orientador: Orival Andries Júnior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação Física / Made available in DSpace on 2018-08-16T18:10:16Z (GMT). No. of bitstreams: 1 Barbosa_AugustoCarvalho_D.pdf: 7576445 bytes, checksum: 04d87ab5c33f1dc5ca635490134e7f67 (MD5) Previous issue date: 2010 / Resumo: O objetivo do presente estudo foi analisar as respostas agudas de parâmetros biomecânicos à utilização de diferentes tamanhos de palmar no nado crawl. Foram selecionados 14 nadadores homens (idade: 20.0 ± 3.7 anos, altura: 1.84 ± 0.08 m, massa corporal: 76.3 ± 8.6 kg, melhor tempo nos 100 m livre: 53.70 ± 0.87 s) competitivos em nível nacional. Para avaliação da força propulsora foram realizados 02 esforços máximos de 10 s no nado completamente atado. Em cada um foram analisadas 08 braçadas consecutivas, de onde se extraiu os valores médios de força pico (Fpico), força média (Fméd), taxa de desenvolvimento de força (TDF), impulso (ImpF), duração da braçada (DUR), tempo para atingir a força pico (TFpico) e força mínima (Fmín). Os nadadores também realizaram 02 esforços máximos na distância de 25m para obtenção da velocidade média em 15m (VM15m) (foram desprezados os 07 primeiros e 03 últimos metros), da frequência (FB15m) e do comprimento de braçadas (CB15m). Ambos os protocolos foram repetidos em 05 situações, a saber: livre de material (LVR), com palmar pequeno (PP, 280 cm²), médio (PM, 352 cm²), grande (PG, 462 cm²) e extragrande (PGG, 552 cm²). A ANOVA one way e o teste de Kruskal-Wallis foram adotados para comparar as situações. Quando detectado um efeito significante, recorreu-se ao teste de post-hoc de Scheffé (dados paramétricos) ou ao teste de Mann-Whitney com ajuste de Bonferroni (dados não-paramétricos) para localização das diferenças. Foi adotado um nível de significância de 5%. O aumento artificial da área da mão possibilitou o deslocamento de uma maior massa de água ocasionando um incremento significante na Fpico nas comparações LVR x PG, LVR x PGG e PP x PGG. Com isso, houve uma diminuição da velocidade da mão, que repercutiu em um aumento da DUR nessas mesmas comparações. Fméd e/ou TDF não apresentaram modificações significantes devido às alterações concomitantes das variáveis cinéticas e temporais que as influenciam. Esse resultado da TDF, aliado ao aumento do ImpF (principal variável associada à velocidade) nas comparações LVR x PG, LVR x PGG e PP x PGG, pode indicar que PG e PGG propiciam o desenvolvimento da propulsão sem ocasionar prejuízos aparentes na capacidade explosiva dos nadadores. O TFpico aumentou de LVR para PGG e PP para PGG devido ao aumento da Fpico e da diminuição da Fmín. A Fmín diminuiu significantemente apenas de LVR para PGG, apontando para uma possível alteração da relação entre o início e término da propulsão de ambos os braços. A ausência de alterações significantes na VM15m pode estar associada ao aumento do arrasto de onda. A FB15m diminuiu significantemente de LVR para PGG e de PP para PGG, enquanto o CB15m apresentou um comportamento exatamente inverso nas mesmas comparações. Conclui-se que, de forma aguda, o tamanho do palmar influencia principalmente a magnitude da força propulsora gerada e o seu comportamento ao longo do tempo / Abstract: The aim of this study was to analyze the acute responses of biomechanical parameters to different sizes of paddles in front-crawl stroke. Fourteen national competitive male swimmers (Age: 20.0 ± 3.7 years, height: 1.84 ± 0.08 m, body mass: 76.3 ± 8.6 kg, 100- m best time: 53.70 ± 0.87 s) volunteered for this investigation. For the propulsive force evaluation, 02 maximum efforts of 10 s were accomplished in the fully tethered swimming. In each effort, 08 consecutive strokes were analyzed to extract the average value of peak force (Fpeak), mean force (Fmean), explosive force (TDF), impulse (ImpF), stroke duration (DUR), time to peak force (TFpeak) and minimum force (Fmin). Additionally, swimmers accomplished two 25-m maximal swimming in order to measure the average velocity in 15 m (VM15m) (first 07 and last 03m were discarded), the stroke rate (SR15m) and the stroke length (SL15m). Both testing protocols were repeated in 05 conditions: conventional swimming (LVR), wearing small (PP, 280 cm²), medium (PM, 352 cm²), large (PG, 462 cm²) and extra-large paddles (PGG, 552 cm²). The one way ANOVA or the Kruskal-Wallis test were adopted for intersituations comparisons. Possible significant differences were detected by Scheffé post-hoc test (for parametric data) or Mann-Whitney test with Bonferroni adjustment (for non-parametric data). The significance level was set at 5%. The artificial enlargement of the hands allowed the swimmers to push off against a bigger mass of water and provided a significant increase of the Fpeak in the comparisons LVR x PG, LVR x PGG and PP x PGG. Because of this, there was also a hand's velocity reduction, which repercuted in a greater DUR in these same comparisons. The Fmean and/or the TDF did not change significantly due to the concomitant modifications of the kinetic and temporal variables that influence them. This result of the TDF, associated to the increase of the ImpF (the main variable related to swimming velocity) in the comparisons LVR x PG, LVR x PGG and PP x PGG, might indicate that PG and PGG propitiate the development of propulsion without any apparent damage in the swimmer's explosiveness. The TFpeak increased from LVR to PGG and from PP to PGG due to the increase of the Fpeak and the decrease of Fmin. The Fmin decrease significantly only from LVR to PGG, pointing to a possible modification in the relation between the beginning and the end of propulsion of both arms. The absence of significant changes in the VM15m might be related to the wave drag increase. The SR15m decrease significantly from LVR to PGG, while the SL15m presented exactly the inverse behavior. It can be concluded that, acutely, the different sizes of hand paddles influence mainly the magnitude of the propulsive force generated and its behavior throughout the time / Doutorado / Ciencia do Desporto / Doutor em Educação Física

The ability of fish to deform their bodies in steady swimming action is gaining from robotic designers. While bound by the same physical laws, fish have evolved to move in ways that often outperform artificial systems in critical measures such as efficiency, agility, and stealth through thousands of years of natural selection. As we expand our presence in the ocean with deep-sea exploration or offshore drilling for petroleum and natural gas, the demand for prolonging underwater operations is growing significantly. Therefore, it is critical for robotic designers to understand the physics of pisciform (fish-like) locomotion and learn how to effectively implement the propulsive mechanisms into their designs to create the next generation of aquatic robots. Aiming to assist this process, this thesis presents an experimental apparatus called Towed Biolocomotion Emulator (TBE), which is capable of imitating the undulating action of different fish species in steady swimming and can be quickly adapted to different configurations with modular modules. Using the TBE device, an experiment is performed to test its hydrodynamic performance and evaluate the effectiveness of the bio-inspired locomotion implemented on such a mechanical system. The analysis of hydrodynamic data collected from the experiment shows that there exists a small range of kinematic parameters where the undulating motion of the device produces the optimal performance. This result confirms the benefits of utilizing pisciform locomotion for small-scale underwater vehicles. In addition, this thesis also proposes a reduced-order flow model using the unsteady vortex lattice method (UVLM) to predict the hydrodynamic performance of such a system. The proposed model is then validated with the experimental data collected earlier. The tool developed can be employed to quickly explore the possible design space early in the conceptual design stage for such a bio-mimetic vehicle. / Master of Science / It is no surprise that through thousands of years of natural evolution, marine species possess incredible ability to navigate through water. As we expand our presence in the sea, more and more tasks require underwater operations such as ocean exploration, oil-rig maintenance, etc. Yet, most of the underwater robotic vehicles still utilize propellers as the primary propulsive mechanism. In many cases, the bio-inspired propulsion system that mimics the swimming action of fish offers many advantages in agility, maneuverability, and stealth. With the rising interest in the field, the works presented in this thesis aim to expand our understanding of how to implement the bio-inspired propulsive mechanism to robotic design. To achieve this, a mechanical device is designed to mimic the swimming action of different fish species. Then, an experiment is performed to subject the device to different fish-like motions and test their effectiveness. In addition, a reduced-ordered model is also introduced as an alternative method to predict the hydrodynamic performance of this propulsive mechanism. The works presented in this thesis help to expand the toolbox available for the engineer to design the next generation of the underwater robotic vehicle.

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Este trabalho apresenta um procedimento simples e robusto para avaliação e análise do desempenho de instalações propulsoras de embarcações de pesca operando no Estado do Espírito Santo. O objetivo é verificar se as embarcações estão operando com baixa eficiência propulsiva, portanto, com consumo de combustível maior do que o desejável, e identificar possíveis ações de melhoria desta eficiência que poderiam ser implementadas com baixo custo. Tendo em vista as condições artesanais da construção e operação das embarcações de pesca no Espírito Santo, o procedimento foi desenvolvido de forma a poder ser aplicado com relativa facilidade pelas pessoas envolvidas na atividade pesqueira artesanal neste Estado. O procedimento envolve o levantamento de informações sobre a geometria do casco, as características da instalação propulsora existente e sobre alguns aspectos do desempenho das embarcações. Para este levantamento são propostos métodos e técnicas suficientemente simples para que possam ser facilmente aplicadas nos estaleiros. Com base nestes dados levantados implementou-se no procedimento proposto diversos algoritmos que permitem determinar o coeficiente propulsivo das embarcações de pesca e a perda de energia útil que ocorre tanto no motor, por conta de condições inadequadas de operação, quanto na transmissão desta energia para o hélice. Para a validação dos métodos e técnicas envolvidos neste procedimento e dos resultados fornecidos por ele, o mesmo foi aplicado em alguns cascos de embarcações de pesca disponíveis em estaleiros visitados no Estado. Para uma destas embarcações o procedimento foi aplicado em sua totalidade, permitindo identificar a baixa eficiência da instalação propulsora e algumas das possíveis causas que provocam a perda de energia útil no sistema. Finalmente, com base nesse exemplo de aplicação, um estudo de possíveis melhorias na instalação propulsora é apresentado ao final do trabalho. / This study presents a simple and robust procedure to the performance evaluation and analysis of propulsion systems of fishing vessels operating in the Espírito Santo State. The goals are to verify if the vessels are operating at low propulsive efficiency, therefore, with a fuel consumption greater than desired, and identify possible actions to improve this efficiency that could be implemented at a low cost. The procedure was developed in view of the conditions of construction and operation of fishing vessels in Espírito Santo, so that it can be applied with relative ease by the people involved in artisanal fishing activity in this State. The procedure involves the collection of information about the geometry of hull, the characteristics of existing propulsion plant and some aspects of the performance of the vessels. To do this data collection, this paper proposes methods and techniques simple enough to be easily applied in the shipyards. Based on these data collected, the proposed procedure implemented several algorithms to ascertain the propulsive coefficient of fishing vessels and the energy loss which may occur due to the inadequate operating conditions and in energy transmission to propeller. It has been applied in some fishing vessel hulls available on sites visited to validate the methods and techniques involved in this procedure and its results. The procedure was applied, in its entirety, in one of this vessels, that allowed to identify the low efficiency of the propulsion plant and some of the possible causes that justify this energy loss in the system. Finally, based on this application example, a study of possible improvements in propulsion plant is presented at the end of work.

Due to a trend towards Ultra High Bypass Ratio engines the corresponding engine/airframe interference is becoming a key aspect in aircraft design. The present economic situation increases the pressure on commercial aviation companies to reduce the Direct Operating Cost, and the environmental situation requires a new generation of aircraft with a lower environmental impact. Therefore detailed aerodynamic investigations are required to evaluate the real benefits of new technologies. The presented research activity is part of a long-term project with the main objective of generating a reliable and accurate tool to predict the performance of an aircraft over the whole flight domain. In particular the aim of this research was to perform advanced CFD in order to establish a tool able to evaluate engine installation effects for different configurations and attitudes. The developed tool can be provided with correlations of the Net Propulsive Force (NPF), the force exerted by the power-plant to the aircraft, as a function of position. This can be done in principle at cruise, hold, climb, descent, take-off and landing, to model the different integration effects at different phases. Due to the complexity of the problem it was only possible at an initial stage to determine these correlations at cruise condition. Two parametric test cases were evaluated, showing that the engine horizontal positioning can influence the mission fuel burn by up to 6.4%. According to the extensive literature review that has been done, this study can be regarded as the first open literature engine position-NPF parametric study using CFD. Even though no correlations were extracted for other conditions; a deployed high-lift wing configuration was also studied in detail, defining the main aerodynamics effects of the engine integration at high angle of attack. A topological study of the high-lift installation vortices is presented in this work and it can be considered the first in the open literature. It should be pointed out that extensive research is currently underway to correctly evaluate the high-lift aerodynamic using CFD. The Propulsive System Integration (PSI) in high-lift conditions is adding flow features to an already demanding problem, making it a real challenge for the numerical methods. Nevertheless the additional effects of a nacelle chine on the maximum lift were also evaluated. The main outcomes of this PhD research were: a coupled performance modelling tool able to handle the effects of engine-airframe integration as a function of geometry and attitude, and a topological study of the high-lift installation vortices. During the course of the work, this research was successfully suggested as an extra activity for the European NEWAC project (New Aero Engine Core Concepts), and resulted in a new deliverable for that project.