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With the proliferation of unmanned aircraft designed for national security and commercial purposes, opportunities exist to create high-fidelity aerodynamic models with flight test techniques developed specifically for remotely piloted aircraft. Then, highly maneuverable unmanned aircraft can be employed to their greatest potential in a safe manner using advanced control laws. In this dissertation, novel techniques are used to identify nonlinear, coupled, aerodynamic models for fixed-wing, unmanned aircraft from flight test data alone. Included are quasi-steady and unsteady nominal flight models, aero-propulsive models, and spinning flight models. A novel flight test technique for unmanned aircraft, excitation with remote uncorrelated pilot inputs, is developed for use in nominal and nonlinear flight regimes. Orthogonal phase-optimized multisine excitation signals are also used as inputs while collecting gliding, aero-propulsive, and spinning flight data. A novel vector decomposition of explanatory variables leads to an elegant model structure for stall spin flight data analysis and spin aerodynamic modeling. Results for each model developed show good agreement between model predictions and validation flight data. Two novel applications of aerodynamic modeling are discussed including energy-based nonlinear directional control and a spin flight path control law for use as a flight termination system. Experimental and simulation results from these applications demonstrate the utility of high-fidelity models developed from flight data. / Doctor of Philosophy / This dissertation presents flight test experiments conducted using a small remotely controlled airplane to determine mathematical equations and parameter values, called models, to describe the airplane's motion. Then, the models are applied to control the path of the airplane. The process to develop the models and predict an airplane's motion using flight data is described. New techniques are presented for data collection and analysis for unusual flight conditions, including a spinning descent. Results show the techniques can predict the airplane's motion very well. Two experiments are presented demonstrating new applications and the usefulness of the mathematical models.

O presente trabalho teve como objetivo geral avaliar a eficiência técnica e econômica do sistema de resfriamento adiabático evaporativo (SRAE) na produção intensiva de leite e como objetivos específicos avaliar a eficiência térmica dos sistemas de resfriamento (aspersão e nebulização), conjugados com a ventilação forçada, na resposta produtiva dos animais, na redução do estresse térmico, seus reflexos no microclima interno e sua eficiência econômica quanto ao consumo de energia e de água. O experimento foi realizado em uma fazenda comercial de produção leiteira, localizada no interior do Estado de São Paulo. Em cada tratamento foram utilizados 10 animais da raça Holandesa em produção, selecionados de acordo com a produção e período de lactação, alojados em sistema de "freestall". Dos animais selecionados cinco foram utilizados para a tomada dos dados fisiológicos dos animais (freqüência respiratória, temperatura retal e temperatura do pelame branco e preto, medidos nos horários das 9, 11, 13, 15 e 17 horas, durante nove dias não consecutivos), e cinco animais foram utilizados para a avaliação comportamental (localização e atividades dentro da instalação), sendo para tanto utilizadas vídeo - câmeras das 9 às 17 horas durante seis dias. O período experimental compreendeu vinte e oito dias consecutivos do mês de novembro de 2003, sendo sete dias utilizados para a adaptação dos animais aos tratamentos testados e vinte e um dias para a coleta de dados. Os dados climáticos (temperatura e umidade relativa do ar e temperatura de globo negro) em cada tratamento e externo à instalação foram registradas a cada 15 minutos ao longo das 24 horas por um data logger HOBO ® , possibilitando o cálculo do Índice de Temperatura e Umidade (THI), do Índice de Globo Negro e Umidade (BGHI) e da entalpia (H). Foram utilizados ventiladores com capacidade de movimentar o ar a 2,5 m.s -1 que, assim como os sistemas de aspersão e nebulização, foram controlados por um termostato e distribuídos ao longo da linha de cocho das instalações. As variáveis respostas consideradas foram: produção de leite, consumo de alimento pelos animais, comportamento dos animais, consumo de água e de energia pelos sistemas de resfriamento e dados fisiológicos dos animais. A avaliação dos dados foi realizada por um delineamento experimental em blocos ao acaso, utilizando-se na análise estatística a comparação de médias pelo teste de Tukey ao nível de 1%. Para a análise geral dos resultados foi utilizado o pacote estatístico SAS (SAS User guide: Statistics (release 6.03). SAS Inst. Inc., 1990). Considerando que os tratamentos estudados: aspersão e nebulização associadas à ventilação forçada promoveram um consumo alimentar semelhante (diferença de 3,0 kg MS -1 .animal -1 .mês -1 ) observou-se que o sistema de resfriamento com aspersão apesar de apresentar um consumo de água e energia maior (7535,7 litros.animal -1 .mês -1 e 13,15 kW.h -1 .animal -1 .mês -1 , respectivamente) promoveu um aumento na produção de leite de 3% (18,0 litros/animal/mês) ocasionando um aumento na receita mensal total de aproximadamente 5,8% por animal quando comparado ao sistema de nebulização. / This work aimed to evaluate the economical and technical efficiency of evaporative adiabatic cooling system (EACS) for intensive milk production. Its specific objectives were to evaluate thermal efficiency of chilling systems (aspersion and sprinkler) associated with forced air fan on productive traits, heat stress reduction, internal micro-climate, and economical advantages in relation to water and energy expenses. Experiment was carried out in a commercial dairy cattle farm located in a small city of São Paulo State. In each treatment were used 10 dairy-Holstein cows sorted according to their milk production and lactation order, in a free-stall system. Among these cows, five were selected for collecting physiological data (respiratory frequency, rectal temperature and temperature in white and black pelage) at 9:00 a.m., 11:00 a.m., 1:00 p.m., 3:00 p.m. and 5:00 p.m. during nine non-consecutive days. Other five animals were evaluated for their behavior (localization and activities inside facilities) through video-cameras from 9:00 a.m. to 5:00 p.m. during six days. Experimental period was twenty-eight consecutive days of November 2003, being the first seven days for animal adaptation and the last twenty-one for data collection. Climate data (relative air temperature and humidity, and dark globe temperature), in each treatment and outside of facility, were taken in intervals of 15 minutes during 24 hours by HOBO ® data logger, which permitted to calculate the Humidity and Temperature Index (HTI), Humidity and Dark Globe Index (HDGI) and Enthalpy (E). Fan with 2.5 m.s -1 of air mobility capacity associated to aspersion and sprinkler systems, were controlled by thermostat and distributed following feeder line of free-stall. Production variables considered were: milk production, feed intake, animal behavior, water and energy consumption of cooling system, and animal physiological traits. Data evaluation was realized in a completely randomized block design using in statistical analysis Tukey’s test with 1% of significance level. General analysis of results was performed through SAS proceedings. Considering that treatments promoted similar feed intake (the difference was 3.0 kg DM.animal -1 .month -1 ), the chilling system associated to aspersion led to an increase (18.0 liters.animal -1 .month -1 ) in 3% milk production in spite of its higher consumption of water and energy (7535.7 liters.animal -1 .month -1 and 2.3 kW.h -1 .animal -1 .month -1 , respectively). As consequence, it was observed an increase of 4.7% in total mensal profit in relation to sprinkler system.

As estruturas aeronáuticas estão sujeitas a diversas solicitações, devido principalmente às interações com o escoamento aerodinâmico, que podem causar distúrbios e vibrações, comprometendo seu desempenho. As medidas aerodinâmicas aplicadas em uma aeronave podem ser obtidas por simulações computacionais ou testes experimentais. No entanto, podem existir imperfeições na simulação computacional, como por exemplo, se conseguir reproduzir algumas condições de vôo real. Sendo assim, diversas pesquisas vêm sendo realizadas para solucionar estes problemas. Dentre elas estão os testes experimentais feitos em túnel de vento com modelos de escala real em diversas condições de vôo. Desta forma, a construção de um modelo físico de um aerofólio em escala reduzida e a implementação de sensores a este modelo torna-se uma ferramenta bastante importante para validar resultados teóricos e experimentais. Assim, nesse trabalho realizou-se a construção de um modelo de aerofólio NACA0012, o desenvolvimento de um mecanismo de fixação do modelo ao túnel de vento e a implementação de um controlador de oscilação forçada. O modelo físico realiza oscilações harmônicas, em regime não-estacionário. O objetivo do trabalho foi mapear as medidas de pressão atuantes sobre modelo ensaiado em regime estacionário e não-estacionário e fazer a comparação entre os dois casos. / Aeronautical structures are affected by many loads, most of them given by the aerodynamic flow interactions. These flow interactions may cause vibration leading to structural failure, such as cracks and fatigue. The aerodynamic flow interactions can be measured by experiment or predicted by computational simulation. Otherwise, computational simulations on its own are not reliable and can not reproduce a real flight condition, such as the mean atmospheric turbulence dynamic. Many researches has been done to solve these problems for computational simulations. One of them are the wind tunnel experiments with a full scale models in many flight conditions for posterior comparison. For a smaller wind tunnel, a small scale physical prototype well instrumented becomes an important solution to validate theoretical and experimental results. In the present work the construction of a NACA 0012 airfoil model, the development of a constraint mechanism and the implementation of a forced oscilation control system were done. The physical model oscilates with a given frequency. The aim of present work is to map the pressure measurements actuating on the model, testing it under a steady state condition and a transient condition for posterior comparison of both conditions.

O presente trabalho teve como objetivo geral avaliar a eficiência técnica e econômica do sistema de resfriamento adiabático evaporativo (SRAE) na produção intensiva de leite e como objetivos específicos avaliar a eficiência térmica dos sistemas de resfriamento (aspersão e nebulização), conjugados com a ventilação forçada, na resposta produtiva dos animais, na redução do estresse térmico, seus reflexos no microclima interno e sua eficiência econômica quanto ao consumo de energia e de água. O experimento foi realizado em uma fazenda comercial de produção leiteira, localizada no interior do Estado de São Paulo. Em cada tratamento foram utilizados 10 animais da raça Holandesa em produção, selecionados de acordo com a produção e período de lactação, alojados em sistema de "freestall". Dos animais selecionados cinco foram utilizados para a tomada dos dados fisiológicos dos animais (freqüência respiratória, temperatura retal e temperatura do pelame branco e preto, medidos nos horários das 9, 11, 13, 15 e 17 horas, durante nove dias não consecutivos), e cinco animais foram utilizados para a avaliação comportamental (localização e atividades dentro da instalação), sendo para tanto utilizadas vídeo - câmeras das 9 às 17 horas durante seis dias. O período experimental compreendeu vinte e oito dias consecutivos do mês de novembro de 2003, sendo sete dias utilizados para a adaptação dos animais aos tratamentos testados e vinte e um dias para a coleta de dados. Os dados climáticos (temperatura e umidade relativa do ar e temperatura de globo negro) em cada tratamento e externo à instalação foram registradas a cada 15 minutos ao longo das 24 horas por um data logger HOBO ® , possibilitando o cálculo do Índice de Temperatura e Umidade (THI), do Índice de Globo Negro e Umidade (BGHI) e da entalpia (H). Foram utilizados ventiladores com capacidade de movimentar o ar a 2,5 m.s -1 que, assim como os sistemas de aspersão e nebulização, foram controlados por um termostato e distribuídos ao longo da linha de cocho das instalações. As variáveis respostas consideradas foram: produção de leite, consumo de alimento pelos animais, comportamento dos animais, consumo de água e de energia pelos sistemas de resfriamento e dados fisiológicos dos animais. A avaliação dos dados foi realizada por um delineamento experimental em blocos ao acaso, utilizando-se na análise estatística a comparação de médias pelo teste de Tukey ao nível de 1%. Para a análise geral dos resultados foi utilizado o pacote estatístico SAS (SAS User guide: Statistics (release 6.03). SAS Inst. Inc., 1990). Considerando que os tratamentos estudados: aspersão e nebulização associadas à ventilação forçada promoveram um consumo alimentar semelhante (diferença de 3,0 kg MS -1 .animal -1 .mês -1 ) observou-se que o sistema de resfriamento com aspersão apesar de apresentar um consumo de água e energia maior (7535,7 litros.animal -1 .mês -1 e 13,15 kW.h -1 .animal -1 .mês -1 , respectivamente) promoveu um aumento na produção de leite de 3% (18,0 litros/animal/mês) ocasionando um aumento na receita mensal total de aproximadamente 5,8% por animal quando comparado ao sistema de nebulização. / This work aimed to evaluate the economical and technical efficiency of evaporative adiabatic cooling system (EACS) for intensive milk production. Its specific objectives were to evaluate thermal efficiency of chilling systems (aspersion and sprinkler) associated with forced air fan on productive traits, heat stress reduction, internal micro-climate, and economical advantages in relation to water and energy expenses. Experiment was carried out in a commercial dairy cattle farm located in a small city of São Paulo State. In each treatment were used 10 dairy-Holstein cows sorted according to their milk production and lactation order, in a free-stall system. Among these cows, five were selected for collecting physiological data (respiratory frequency, rectal temperature and temperature in white and black pelage) at 9:00 a.m., 11:00 a.m., 1:00 p.m., 3:00 p.m. and 5:00 p.m. during nine non-consecutive days. Other five animals were evaluated for their behavior (localization and activities inside facilities) through video-cameras from 9:00 a.m. to 5:00 p.m. during six days. Experimental period was twenty-eight consecutive days of November 2003, being the first seven days for animal adaptation and the last twenty-one for data collection. Climate data (relative air temperature and humidity, and dark globe temperature), in each treatment and outside of facility, were taken in intervals of 15 minutes during 24 hours by HOBO ® data logger, which permitted to calculate the Humidity and Temperature Index (HTI), Humidity and Dark Globe Index (HDGI) and Enthalpy (E). Fan with 2.5 m.s -1 of air mobility capacity associated to aspersion and sprinkler systems, were controlled by thermostat and distributed following feeder line of free-stall. Production variables considered were: milk production, feed intake, animal behavior, water and energy consumption of cooling system, and animal physiological traits. Data evaluation was realized in a completely randomized block design using in statistical analysis Tukey’s test with 1% of significance level. General analysis of results was performed through SAS proceedings. Considering that treatments promoted similar feed intake (the difference was 3.0 kg DM.animal -1 .month -1 ), the chilling system associated to aspersion led to an increase (18.0 liters.animal -1 .month -1 ) in 3% milk production in spite of its higher consumption of water and energy (7535.7 liters.animal -1 .month -1 and 2.3 kW.h -1 .animal -1 .month -1 , respectively). As consequence, it was observed an increase of 4.7% in total mensal profit in relation to sprinkler system.

L'éolienne Darrieus connaît un intérêt accru ces dernières années parce qu'elle représente une solution alternative potentielle de production d'électricité dans les milieux urbains. En particulier,une éolienne de forte solidité peut être choisie car certaines de ses propriétés peuvent être avantageuses pour son implantation proche de zones habitées. A l'inverse, certaines difficultés aérodynamiques émergent. Ce type d'éolienne fonctionne à de faibles vitesses réduites pour lesquelles le décrochage dynamique a un rôle très significatif. L'objectif de ce travail de thèse consiste à compléter la connaissance du phénomène de décrochage dynamique sur une éolienne à axe vertical afin d'améliorer les modèles numériques de prédiction existants. Cette étude s'appuie sur une analyse combinée de résultats numériques et expérimentaux. Les simulations numériques sont produites avec une méthode des panneaux bidimensionnelle instationnaire. Les effets de la viscosité sont introduits par des corrections utilisant notamment un modèle semi-empirique de décrochage dynamique. Le travail expérimental s'est concentrée sur la dynamique tourbillonnaire à proximité immédiate du rotor résultante du décrochage dynamique. Le montage se compose d'une éolienne à pale droite placée dans une soufflerie. Des mesures instationnaires de la répartition de pression pariétale le long de la corde et des mesures de champ de vitesse par vélocimétrie par images de particules ont été accomplies. Les résultats révèlent la manière dont les caractéristiques du décrochage dynamique sont conditionnées par la vitesse réduite. Le retard au décrochage, l'intensité de l'effet du tourbillon de décrochage dynamique et sa convection ont été quantifiés. Enfin, un examen critique de l'applicabilité du modèle de Leishman-Beddoes pour simuler efficacement les effets du décrochage dynamique a été réalisé. / The Darrieus wind turbine has entered a period of renewed interest over the last years because it may stand for an alternative solution to produce electricity in urban areas. In particular, high solidity wind turbine can be chosen to take benefit from some of its key properties for use near populated city areas. Conversely, some aerodynamic problems arise. This type of wind turbine operates at low tip speed ratio for which dynamic stall has a very significant role. The goal of this work is to provide valuable data to complement the knowledge of the dynamic stall phenomenon that occurs on a vertical axis wind turbine in order to improve existing numerical models. This study relies on a combined analysis of numerical and experimental results. The numerical simulations are based on a bidimensional unsteady vortex panel method. Effects of viscosity are introduced by adding corrections computed with a semi-empirical dynamic stall model. The experimental work focuses on the dynamics of the shed vortices existing in the vicinity of the rotor as a result of dynamic stall. The set-up consists of a straight-bladed wind turbine tested in a wind tunnel. Unsteady pressure distribution measurements along the chord and velocity fields measurements by particle image velocimetry were carried out. Results indicate how the characteristics of dynamic stall are conditioned by the tip speed ratio. Stall inception delay, magnitude of the dynamic stall vortex effects and its convection velocity were evaluated. Blade/Vortex interaction was analyzed through the observation of the vortical system downstream of the rotor. In addition, a critical review of the suitability of the Leishman-Beddoes model to effectively simulate the effects of dynamic stall was accomplished.

No description available.

<p>A series of aeroelastic analyses is performed for a flexible high-aspect-ratio wing representative of a high altitude long endurance (HALE) aircraft. Such aircraft are susceptible to dynamic instabilities such as flutter, which can lead to large amplitude limit cycle oscillations. These structural motions are modeled by a representative linear typical section model and by Hodges-Dowell beam theory, which includes leading-order nonlinear elastic coupling. Aerodynamic forces are represented by the ONERA dynamic stall model with its coefficients calibrated to CFD data versus wind tunnel test data. Time marching computations of the coupled nonlinear beam and ONERA system highlight a number of features relevant to the aeroelastic response of HALE aircraft, including the influence of a tip store, the sensitivity of the flutter boundary and limit cycle oscillations to aerodynamic CFD or test data, and the roles of structural nonlinearity and nonlinear aerodynamic stall in the dynamic stability of high-aspect-ratio wings.</p> / Dissertation

This work addressed aerodynamic modeling methods for prediction of post-stall flight dynamics of large transport aircraft. This was accomplished by applying historically successful modeling methods used on high-performance military aircraft to a transport configuration. The overall research approach involved integrating forced oscillation and rotary balance wind tunnel data into an aerodynamic model using several methods of blending these data. The complete aerodynamic model was integrated into a six degree-of-freedom simulation. Experimental data from free-spin wind tunnel testing was used to validate the aerodynamic modeling methods by comparing aerodynamic force and moment coefficients and also to validate the simulation performance by comparing spin mode characteristics and time histories. The aerodynamic model prediction of spin dynamics was generally very good using all of the blending methods studied. In addition, key spin mode characteristics were predicted with a high degree of accuracy. Overall, using the Hybrid Kalviste method of blending forced oscillation and rotary balance data produced the closest match to the free-spin data when comparing aerodynamic coefficients and spin mode characteristics. Several issues were encountered with the blending methods that were exacerbated by nonlinearities and asymmetries in the dynamic aerodynamic data. A new method of looking up dynamic aerodynamic data was proposed to address shortcomings in the blending methods and recommendations were provided on addressing issues with the dynamic aerodynamic data.

Axial compressors are used in a wide variety of aerodynamic applications and are one of the most important components in aero-engines. The operability of compressors is however limited at low-mass flow rates by fluid dynamic instabilities such as stall and surge. These instabilities can lead to engine failure and loss of engine power which can compromise the aircraft safety and reliability. Therefore, a better understanding of how stall occurs and the causes behind its inception is extremely important. In the vicinity of the stall line, the flow field is inherently unsteady due to the interactions between adjacent rows of blades, formation of separation cells, and the viscous effects including shock-boundary layer interaction. Accurate modeling of these phenomena requires a proper set of stable and accurate boundary conditions at the rotorstator interface that conserve mass, momentum and energy, while eliminating false reflections. As a part of this effort, an existing 3D Navier-Stokes analysis for modeling single stage compressors has been modified to model multi-stage axial compressors and turbines. Several rotor-stator interface boundary conditions have been implemented. These have been evaluated for the first stage (a stator and a rotor) of the two stage fuel turbine on the space shuttle main engine (SSME). Their effectiveness in conserving global properties such as mass, momentum, and energy across the interface, while yielding good performance predictions has been evaluated. While all the methods gave satisfactory results, a characteristic based approach and an unsteady sliding mesh approach are found to work best. Accurate modeling of the formation of stall cells requires the use of advanced turbulence models. As a part of this effort, a new advanced turbulence model called Hybrid RANS/KES (HRKES) has been developed and implemented. This model solves Menter's k--SST model near walls and switches to a Kinetic Eddy Simulation (KES) model away from walls. The KES model solves directly for local turbulent kinetic energy and local turbulent length scales, alleviating the grid spacing dependency of the length scales found in other Detached Eddy Simulation (DES) and Hybrid RANS/LES (HRLES) models. Within the HRKES model, combinations of two different blending functions have been evaluated for blending the near wall model to the KES model. The use of realizability constraints to bound the KES model parameters has also been studied for several internal and external flows. The current methodology is used in the prediction of the performance map for the NASA Stage 35 compressor configuration as a representative of a modern compressor stage. The present approach is found to satisfactory predict the onset of stall. It is found that the rotor blade tip leakage vortex and its interaction with the shock wave is mainly the reason behind the stall inception in this compressor stage.