CD-ROM containing source codes of the numerical scheme (appendix A) is attached to back cover. / Includes bibliographical references (leaves 459-472). / System requirements for accompanying CD-ROM: Macintosh or IBM compatible computer. Other requirements: Adobe Acrobat Reader. / xxxvi, 473 leaves ; ill. ; 30 cm. + 1 computer optical disk (4 3/4 in.) / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A numerical scheme, based on discrete-vortex and surface-vorticity boundary-integral methods, has been developed for stimulating time dependent, two-dimensional, viscous flow over arbitary arrays of solid bodies of arbitary cross-section / Thesis (Ph.D.)--Adelaide University, Dept. of Mechanical Engineering, 2001

Thesis(M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.

Thesis (M.S.) -- Mississippi State University. Department of Aerospace Engineering. / Title from title screen. Includes bibliographical references.

Orientadores: Antonio Augusto Fasolo Quevedo, Waldir Antonio Bizzo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-14T20:06:15Z (GMT). No. of bitstreams: 1 Ramos_AndredePaula_M.pdf: 3634888 bytes, checksum: 6ac215157ad6cab344d793b24a2bc1cd (MD5) Previous issue date: 2009 / Resumo: O espirômetro é um dispositivo que avalia a ventilação pulmonar. Este é um trabalho preliminar que propõe um sensor eletromecânico de fluxo com foco na aplicação biomédica de espirometria. O sensor consiste de um corpo rombudo, introduzido em um cano por um orifício, e um acelerômetro. A colisão das partículas do fluido contra o corpo rombudo gera vórtices, que por sua vez induzem vibrações no corpo. Forças de arrasto também estão presentes e tendem a movimentar o corpo. Os movimentos decorrentes do escoamento são captados pelo acelerômetro, que é posicionado na porção do corpo rombudo externa ao cano, evitando o contato do elemento eletrônico (acelerômetro) com o fluido, o que pode facilitar procedimentos de esterilização da luz do cano. Foram analisados corpos rombudos em forma de lâmina (com e sem massa adicional) e cilindro. O procedimento experimental consistiu no estabelecimento de seis regimes permanentes de entrada (vazão de ar) e na captura do sinal de resposta do sensor (nos três eixos). Foram coletadas 24 respostas do sensor para cada um dos regimes e posteriormente foram levantadas as curvas do sensor e realizadas análises estatísticas. Resultados significativos foram encontrados para o eixo do acelerômetro paralelo ao fluxo. Para a lâmina, o Valor Eficaz (RMS) do sinal foi proporcional à vazão com linearidade e coeficiente de correlação variando, respectivamente, de 19% e R2 = 0,99058, para o ensaio sem massa adicional, a até 8,4% e R2 = 0,9741, para o ensaio com massa adicional. O arrasto contínuo (valor médio da resposta) não guardou relação monotônica com o aumento da velocidade do ar. Já para o cilindro, o arrasto foi proporcional à vazão com altíssima linearidade e correlação (0,17% e R2 = 0,96347), mas o RMS do sinal não guardou relação monotônica com a vazão. Finalmente, embora sejam necessários mais estudos para utilizar o sensor proposto em equipamentos de espirometria, este trabalho demonstra que o sensor responde proporcionalmente às entradas (escoamento), dentro (de 0 a até 14 l/s) e fora da faixa (até 21 l/s) de operação do espirômetro com altos coeficientes de correlação e linearidade, além de respostas diferenciadas dadas diferentes entradas (vazões) comprovadas por ANOVA (valor de p < 10-15). / Abstract Spirometer is a device that evaluates pulmonary ventilation. This paper presents a preliminary study of a new electromechanical sensor, focused on the biomedical application of spirometry. The sensor is composed of a bluff body positioned inside a tube trough a hole, being a part of the body inside and another part outside of the tube, and an accelerometer positioned on the outside part. Within a fluid flow, the bluff body causes vortex shedding, and the vortexes induce vibrations on the body. Also, the viscous force of the flow drags the bluff body. Both movements are captured by the accelerometer and correlated with the flow. One important feature of this sensor is that the fluid does not contact any of the electronics, easing tube lumen sterilization procedures. Three types of bluff bodies were studied: two blades (with and without additional mass), and one cylinder. The experimental procedure consisted of establishing six different air flows and then capturing the accelerometer response in all of its three axes. Each of the collected signals from the accelerometer was divided in 24 parts, and these parts where analyzed through statistics; finally the mean response of the sensor was plotted. Best results were found in the accelerometer axis parallel to the air flow. In the blade tests, the RMS value of the AC component was proportional to the air flow, with linearity and correlation varying, respectively, from 19% and R2 = 0.99058 for the blade without mass, to 8.4% and R2 = 0.9741 for the blade with additional mass. It was observed that the mass addition reduced in a meaningful way the response variances. Yet the viscous force (DC value) did not respond in a monotonic way with the increase of air flow. On the other hand, the viscous force was the most expressive regarding the experiments with the cylinder (linearity of 0.17% and R2 = 0.96347), but the RMS value did not respond in a monotonic way. Finally, although further studies are needed to prove that the proposed sensor is efficient to be used in spirometry equipment, this study demonstrates that this sensor responds proportionally to the flow input, within (0 to 14 l/s) and without (up to 21 l/s) the spirometer operation range, with high correlation and linearity, as well as varying responses, given different inputs (flow), as verified by ANOVA test (p < 10-15). / Mestrado / Engenharia Biomedica / Mestre em Engenharia Elétrica

Thesis: Ph. D., Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 283-314). / Animal movement is motivated in part by energetic constraints, where fitness is maximized by minimizing energy consumption. The energetic cost of movement depends on the resistive forces acting on an animal; changes in this force balance can occur naturally or unnaturally. Fishing gear that entangles large whales adds drag, often altering energy balance to the point of terminal emaciation. An analog to this is drag from tags attached to cetaceans for research and monitoring. This thesis quantifies the effects of drag loading from these two scenarios on fine-scale movements, behaviors and energy consumption. I measured drag forces on fishing gear that entangled endangered North Atlantic right whales and combined these measurements with theoretical estimates of drag on whales' bodies. Entanglement in fishing gear increased drag forces by up to 3 fold. Bio-logging tags deployed on two entangled right whales recorded changes in the diving and fine-scale movement patterns of these whales in response to relative changes in drag and buoyancy from fishing gear and through disentanglement: some swimming patterns were consistently modulated in response. Disentanglement significantly altered dive behavior, and can affect thrust production. Changes in the force balance and swimming behaviors have implications for the survival of chronically entangled whales. I developed two bioenergetics approaches to estimate that chronic, lethal entanglements cost approximately the same amount as the cost of pregnancy and supporting a calf to near-weaning. I then developed a method to estimate drag, energy burden and survival of an entangled whale at detection. This application is essential for disentanglement response and protected species management. Experiments with tagged bottlenose dolphins suggest similar responses to added drag: I determined that instrumented animals slow down to avoid additional energetic costs associated with drag from small bio-logging tags, and incrementally decrease swim speed as drag increases. Metabolic impacts are measurable when speed is constrained. I measured the drag forces on these tags and developed guidelines depending on the relative size of instruments to study-species. Together, these studies quantify the magnitude of added drag in complementary systems, and demonstrate how animals alter their movement to navigate changes in their energy landscape associated with increased drag. / by Julie M. van der Hoop. / Ph. D.

The present study was undertaken to determine the effects of the aerodynamics on a close earth orbit and reentry trajectory. The aerodynamic influence is compared to the effects of the earth’s oblateness, the sun, and the moon. In order to obtain maximum accuracy and computational speed Encke’s perturbative procedures were used during orbital periods and Cowell’s integration procedures during thrust and reentry periods. / M.S.

Newtonian theory was applied, in this analysis, to the elliptic cone segment at angles of attack and sideslip. Closed form expressions for the aerodynamic coefficients and static stability derivatives were obtained. Expressions for the full and half conic bodies were given and approximate expressions were given for the half cone case. The circular cone results were obtained as a special case of the general results. Comparisons of the theoretical calculations with experimental results at hypersonic speeds were made of the aerodynamic coefficients and static derivatives for several conic segments. Generally, good agreement was observed for specified ranges of fineness ratios and angles of attack. / Master of Science

This thesis describes the development and implementation of new computational techniques to predict installation losses for mixed compression inlets and a study of advanced technology nozzles. The new computational techniques have been created to predict drag and total pressure recovery for both axisymmetric and 2-D mixed compression inlet configurations. These inlets are designed for use in aircraft with sustained supersonic cruise capabilities such as the HSCT. The drag and pressure recovery prediction methods have been added to ACSYNT, an aircraft conceptual design program. Also included in this thesis is a survey of the performance of advanced technology nozzles. Axisymmetric and nonaxisymmetric geometries are considered, as are non thrust-vectoring nozzles. Only the internal losses of these nozzles are considered, and these losses are characterized by the thrust coefficient. The results of this survey have also been added to ACSYNT to extend the thrust prediction capabilities of the code. / Master of Science

The problem of bluff body flows and the drag associated with them has been the subject of numerous investigations in the literature. In the two-dimensional case, the flow past a circular cylinder has been most widely studied both experimentally and computationally. As a result, a well documented understanding of the gross features of the near-wake around a circular cylinder exists in the literature. In contrast, very little is understood on the general features of three-dimensional bluff body near-wakes, except that the vortex shedding is known to be less intense. Control or management of bluff body flows, both from the point of view of drag reduction as well as suppressing unsteady forces caused by vortex shedding, has been an area of considerable interest in engineering applications. The basic aim in the different control methods involves direct or indirect manipulation (or modification) of the near-wake structure leading to weakening or inhibition of vortex shedding. Many passive and energetic techniques (such as splitter plates, base and trailing edge modifications and base bleed) have been effective in the two-dimensional case in increasing the base pressure, leading to varying amounts of drag reduction; a large body of this work is centered around circular cylinders because of direct relevance in applications. The present work is an attempt to understand some of the major aspects of the near-wake structure of a sphere and to control the same for drag reduction employing a passive technique. Many of the passive control techniques found useful in two-dimensional flows are not appropriate in the context of a sphere. In this thesis, the effects of natural ventilation on the wake and drag of a sphere at low speeds have been studied experimentally in some detail. Natural bleed into the base is created when the stagnation and base regions of a sphere are connected through an internal duct. Although natural ventilation has features broadly similar to the well known base-bleed technique (both involve addition of mass, momentum and energy into the near-wake), there are many significant differences between the two methods; for example, in base bleed, the mass flow injected can be controlled independent of the outer flow, whereas in natural ventilation, it is determined by an interaction between the internal and the external flow around the body. Experiments have been conducted in both wind and water tunnels, which covered a wide range of Reynolds number (ReDj based on the diameter of the sphere) from of 1.7 x 103 to 8.5 x 105 with natural boundary layer transition. The ratio of the frontal vent area to the maximum cross sectional area of the sphere was varied from 1% to 2.25% and the effect of the internal duct geometry, including a convergent and a divergent duct was examined as well. After preliminary force measurements involving different duct geometries and vent areas, it was decided to make detailed measurements with a straight (parallel) duct with a vent area ratio of 2.25%. Extensive flow visualization studies involving dye-flow, hydrogen bubble, surface oil-flow and laser-light-sheet techniques were employed to gain insight into many aspects of the near-wake structure and the flow on the surface of the sphere. Measurements made included model static pressures, drag force using a strain gauge balance and velocity profiles in the near-wake and internal flow through the vent. In addition, wake vortex shedding frequency was measured using a hotwire. In the subcritical range of Reynolds numbers (ReD< 2 x 105), the near-wake of the sphere (without ventilation) was found to be vortex shedding, with laminar separation occurring around a value of0s = 80° (where 0s is the angle between the stagnation point and separation location). In contrast, there was little evidence of vortex shedding in the supercritical range (ReD> 4 x 105), consistent with many earlier observations in the literature; however, flow visualization studies in the near-wake clearly showed the existence of a three-dimensional vortex-like structure exhibiting random rotations about the streamwise axis. In this range of Reynolds numbers, surface flow visualization studies indicated the existence of a laminar separation bubble which was followed by a transitional/turbulent reattachment and an ultimate separation around 0S = 145°. All the above observations are broadly consistent with the results available in the literature. With ventilation at subcritical Reynolds numbers, the pressure distributions on the sphere including in the base region was only weakly altered, resulting in a marginal reduction in the total drag; because of the higher pressure difference between the stagnation and base regions, the mean velocity in the vent-flow was about 0.9 times the free-stream velocity. As may be expected, there was little change in the location of laminar separation on the sphere and the vortex shedding frequency was virtually unaltered due to ventilation. The relatively small effects on pressure distribution and drag suggest weak interaction between the vent-flow and the separated shear layer in the subcritical regime. The time-averaged near-wake flow revealed a stagnation point occurring between the vent-flow and the reverse flow in the near-wake, along with the formation of a torroidal vortex between the stagnation point and the near-wake closure; these features bear some resemblance to those observed with base bleed from a blunt base. With ventilation in the supercritical range of Reynolds numbers (ReD > 4 x 105), significant reduction in the total drag, of as much as 65%, was observed from force measurements. Pressure distributions showed higher pressures in the separated flow zone (consistent with reduced drag) as a result of which the internal mass and the mean velocity of the vent-flow were lower (0.69 times the free-stream velocity) compared to the value in the subcritical flow regime. Flow visualization studies clearly showed that the three-dimensional rotating structure (associated with the wake of the unvented sphere) was significantly modified by ventilation, leading to more symmetric and steady near-wake features. The larger effects on pressure distribution and drag suggest strong interaction between the vent-flow and the separated shear layer, promoted by their close proximity. The comparison of power spectral density of u1 signals in the near-wake showed significant reduction in the amplitude at all frequencies, consistent with observations from flow visualization studies. The time-averaged near-wake flow features a pair of counterrotating ring vortices which are trapped between the outer separated shear layer and the vent-flow shear layer; such a mean flow pattern is qualitatively similar to that behind an axisymmetric base with a central jet with unequal freestream velocities in the jet and outer flow. This study strongly suggests that natural ventilation can provide significant total drag reduction provided the vent-flow is in close proximity of the separated shear layer promoting a strong interaction between them. Drag reduction is associated with more symmetric and relatively steady near-wake features in contrast with the unvented sphere.

The emerging and competitive environment in the space technology requires the improvements in the capability of aerodynamic vehicles. This leads to the analysis in drag reduction of the vehicle along with the minimized heat transfer rate. Using forward facing solid aerospike is the simplest way among the existing drag reduction methodologies for hypersonic blunt cone bodies. But the flow oscillations associated with this aerospike makes it difficult to implement. When analyzing this flow, it can be understood that this oscillating flow can be compared to conical cavity flow. Therefore in the spiked flows, it is decided to implement the technique used in reducing the flow oscillation of the cavities. Based on this method the shallow conical cavity flow generated by the aerospike fixed ahead of a 120o blunt cone body is fissured as multiple cavities by so many disks formed from 10o cone. Now the deep conical cavities had the length to mean depth ratio of unity; this suppresses the unnecessary oscillations of the shallow cavity. The total length of the telescopic aerospike is fixed as 100mm. And one another conical tip plain aerospike of same length is designed for comparing the telescopic spike’s performance at hypersonic flow Mach numbers of 5.75 and 7.9. A three component force balance system capable of measuring drag, lift and pitching moment is designed and mounted internally into the skirt of the model. Drag measurement is done for without spike, conical tip plain spiked and telescopic spiked blunt cone body. The three configurations are tested at different angles of attack from 0 to 10 degree with a step of 2. A discrete iterative deconvolution methodology is implemented in this research work for obtaining the clean drag history from the noisy drag accelerometer signal. The drag results showed the drag reduction when compared to the without spike blunt cone body. When comparing to the plain spiked, the telescopic spiked blunt cone body has lesser drag at higher angles of attack. Heat transfer measurements are done over the blunt cone surface using the Platinum thin film gauges formed over the Macor substrate. These results and the flow visualization give better understanding of the flow and the heat flux rate caused by the flow. The enhancement in the heat flux rate over the blunt cone surface is due to the shock interaction. And in recirculation region the heat flux rate is very much lesser when compared to without spike blunt cone body. It is observed that the shock interaction in the windward side is coming closer towards the nose of the blunt cone as the angle of attack increases and the oscillation of the oblique shock also decreases. Schlieren visualization showed that there is dispersion in the oblique shock, particularly in the leeward side. In the telescopic spike there are multiple shocks generated from each and every disk which coalesces together to form a single oblique shock. And the effect of the shock generated by the telescopic spike is stronger than the effect of the shock generated by the conical tip plain spike.