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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Análise experimental do efeito aerodinâmico de dispositivos de asa e ponta de asa em uma aeronave tipo \"Blended Wing Body\" / Experimental analysis of the aerodynamic effect of the wing and wing tip devices on a \"Blended Wing Body\"

Diaz Izquierdo, David Orlando 21 October 2015 (has links)
Este trabalho tem por objetivo analisar o comportamento aerodinâmico de dispositivos de ponta de asa e Fences acoplados em uma aeronave Blended Wing Body (BWB) através de testes em túnel de vento. A BWB é um projeto de aeronave alternativo que faz parte do conceito de aeronaves sustentáveis. O Laboratório de Aeronaves da Escola de Engenharia de São Carlos, Universidade de São Paulo, vem realizando uma série de pesquisas sobre este assunto. Em trabalhos anteriores com o modelo BWB foram observados a presença tanto de um escoamento transversal na parte externa quanto um forte vórtice no meio do modelo. A fim de melhorar o primeiro protótipo o Droop, bem como um arranjo de três Fences foram adicionados no modelo BWB. Além disso, os dispositivos Winglets e C-wing foram considerados neste estudo. Entre o desenvolvimento de aeronaves, vários dispositivos têm sido estudados e implementados em aeronaves convencionais. Estes tem várias vantagens, tais como a melhoria da eficiência aerodinâmica e a redução do arrasto induzido e efeitos positivos no rendimento do avião. Os dispositivos de ponta da asa criam uma força aerodinâmica em que um do seus componentes atua na direção do voo, esta também pode contribuir para a redução da intensidade dos vórtices nas pontas da asa, reduzindo o arrasto induzido. Pesquisas em aeronaves não convencionais mostraram que BWB poderia ter melhores características aerodinâmicas do que uma aeronave convencional. Aindústriaaeronáuticaestáprocurandoareduçãodoscustosoperacionais,bemcomo a adaptação das aeronaves para a restrição legislativa das emissões de gases e poluição sonora. Nas últimas décadas, esta redução não teve uma melhora significativa em termos de valores absolutos para configurações convencionais, isso fez com que novas e mais eficientes configurações têm sido estudadas. A interferência dos diferentes dispositivos no modelo BWB foram analisados em teste em túnel de vento. Os experimentos foram realizados no Laboratório de Aeronaves da Escola de Engenharia de São Carlos, Universidade de São Paulo. Foi utilizado um túnel de vento fechado com uma seção de teste de 1.7x1.3x3 [m]. O ângulo de ataque foi variado desde -4º a 20º e Re = 390.000. Os resultados mostram que os dispositivos nas pontas da asa melhoraram o desempenho da aeronave, bem como a eficiência aerodinâmica. Com relação aos Fence este comportamento não foi observado. Entre tanto, em ângulos elevados a eficiência foi aumentada. Através da técnica de visualização oil flow observou-se que o escoamento sobre a asa foi redirecionado diminuindo o coeficiente de arrasto em ângulos de ataque elevados. / This work aims to analyze the aerodynamic behavior of wingtip devices and Fences coupled on a Blended Wing Body aircraft (BWB) through wind tunnel tests. The BWB is an alternative of airship design which makes up part of the Green aircraft concept. The Aircraft Laboratory of the School of Engineering of São Carlos-University of São Paulo has been carrying out a lot of research into this subject. In previous works with a BWB model, the presence both of a cross flow on the external part and a stronger vortex in the middle of the model have been observed. In order to improve the first prototype a Droop as well as an arrangement of three Fences were added on the BWB model. Furthermore the Winglets, C-wing devices were considered in this study. Among the aircraft development, several devices have been studied and implemented in conventional aircraft. These ones had several advantages such as improving the aerodynamic efficiency and induced drag reduction and getting positive effects on aircraft performance. The wingtip devices create an aerodynamic force in which one of this components acts in the flight direction, also these can contribute to the reduction of the wingtip vortices strength, reducing the induced drag. Researches in non conventional aircraft has shown that BWB could have better aerodynamic characteristics than a conventional aircraft. The aeronautical industry is looking for the reduction of direct operational cost, as well as the adaptation of aircrafts to the demanding legislative restriction of gas emissions and noise pollution. In the last few decades this reductions has not had a significant improvement in terms of absolute values for conventional configurations, this has meant that new and more efficient configurations have been studied. The interference of the different devices on the BWB model were analyzed in wind tunnel test. The experiments were carried out in the Aircraft Laboratory of the School of Engineering of São Carlos-University of São Paulo. A closed wind tunel with a section work of 1.7x1.3x3 [m] was used. The angle of attack was varied from -4º to 20º and Re = 390.000. The results shows that the wing tip devices improved the aircraft performance as well as the aerodynamic efficiency. Regarding the Fences this behavior was not observed. However, at higher angles the efficiency was increased. Through oil flow visualization it was observed that the flow over the wing was redirected decreasing the drag coeficient at higher attack angles.
2

Análise experimental do efeito aerodinâmico de dispositivos de asa e ponta de asa em uma aeronave tipo \"Blended Wing Body\" / Experimental analysis of the aerodynamic effect of the wing and wing tip devices on a \"Blended Wing Body\"

David Orlando Diaz Izquierdo 21 October 2015 (has links)
Este trabalho tem por objetivo analisar o comportamento aerodinâmico de dispositivos de ponta de asa e Fences acoplados em uma aeronave Blended Wing Body (BWB) através de testes em túnel de vento. A BWB é um projeto de aeronave alternativo que faz parte do conceito de aeronaves sustentáveis. O Laboratório de Aeronaves da Escola de Engenharia de São Carlos, Universidade de São Paulo, vem realizando uma série de pesquisas sobre este assunto. Em trabalhos anteriores com o modelo BWB foram observados a presença tanto de um escoamento transversal na parte externa quanto um forte vórtice no meio do modelo. A fim de melhorar o primeiro protótipo o Droop, bem como um arranjo de três Fences foram adicionados no modelo BWB. Além disso, os dispositivos Winglets e C-wing foram considerados neste estudo. Entre o desenvolvimento de aeronaves, vários dispositivos têm sido estudados e implementados em aeronaves convencionais. Estes tem várias vantagens, tais como a melhoria da eficiência aerodinâmica e a redução do arrasto induzido e efeitos positivos no rendimento do avião. Os dispositivos de ponta da asa criam uma força aerodinâmica em que um do seus componentes atua na direção do voo, esta também pode contribuir para a redução da intensidade dos vórtices nas pontas da asa, reduzindo o arrasto induzido. Pesquisas em aeronaves não convencionais mostraram que BWB poderia ter melhores características aerodinâmicas do que uma aeronave convencional. Aindústriaaeronáuticaestáprocurandoareduçãodoscustosoperacionais,bemcomo a adaptação das aeronaves para a restrição legislativa das emissões de gases e poluição sonora. Nas últimas décadas, esta redução não teve uma melhora significativa em termos de valores absolutos para configurações convencionais, isso fez com que novas e mais eficientes configurações têm sido estudadas. A interferência dos diferentes dispositivos no modelo BWB foram analisados em teste em túnel de vento. Os experimentos foram realizados no Laboratório de Aeronaves da Escola de Engenharia de São Carlos, Universidade de São Paulo. Foi utilizado um túnel de vento fechado com uma seção de teste de 1.7x1.3x3 [m]. O ângulo de ataque foi variado desde -4º a 20º e Re = 390.000. Os resultados mostram que os dispositivos nas pontas da asa melhoraram o desempenho da aeronave, bem como a eficiência aerodinâmica. Com relação aos Fence este comportamento não foi observado. Entre tanto, em ângulos elevados a eficiência foi aumentada. Através da técnica de visualização oil flow observou-se que o escoamento sobre a asa foi redirecionado diminuindo o coeficiente de arrasto em ângulos de ataque elevados. / This work aims to analyze the aerodynamic behavior of wingtip devices and Fences coupled on a Blended Wing Body aircraft (BWB) through wind tunnel tests. The BWB is an alternative of airship design which makes up part of the Green aircraft concept. The Aircraft Laboratory of the School of Engineering of São Carlos-University of São Paulo has been carrying out a lot of research into this subject. In previous works with a BWB model, the presence both of a cross flow on the external part and a stronger vortex in the middle of the model have been observed. In order to improve the first prototype a Droop as well as an arrangement of three Fences were added on the BWB model. Furthermore the Winglets, C-wing devices were considered in this study. Among the aircraft development, several devices have been studied and implemented in conventional aircraft. These ones had several advantages such as improving the aerodynamic efficiency and induced drag reduction and getting positive effects on aircraft performance. The wingtip devices create an aerodynamic force in which one of this components acts in the flight direction, also these can contribute to the reduction of the wingtip vortices strength, reducing the induced drag. Researches in non conventional aircraft has shown that BWB could have better aerodynamic characteristics than a conventional aircraft. The aeronautical industry is looking for the reduction of direct operational cost, as well as the adaptation of aircrafts to the demanding legislative restriction of gas emissions and noise pollution. In the last few decades this reductions has not had a significant improvement in terms of absolute values for conventional configurations, this has meant that new and more efficient configurations have been studied. The interference of the different devices on the BWB model were analyzed in wind tunnel test. The experiments were carried out in the Aircraft Laboratory of the School of Engineering of São Carlos-University of São Paulo. A closed wind tunel with a section work of 1.7x1.3x3 [m] was used. The angle of attack was varied from -4º to 20º and Re = 390.000. The results shows that the wing tip devices improved the aircraft performance as well as the aerodynamic efficiency. Regarding the Fences this behavior was not observed. However, at higher angles the efficiency was increased. Through oil flow visualization it was observed that the flow over the wing was redirected decreasing the drag coeficient at higher attack angles.
3

Aerodynamic Analysis of a Blended-Wing-Body Aircraft Configuration

Ikeda, Toshihiro, toshi.ikeda@gmail.com January 2006 (has links)
In recent years unconventional aircraft configurations, such as Blended-Wing-Body (BWB) aircraft, are being investigated and researched with the aim to develop more efficient aircraft configurations, in particular for very large transport aircraft that are more efficient and environmentally-friendly. The BWB configuration designates an alternative aircraft configuration where the wing and fuselage are integrated which results essentially in a hybrid flying wing shape. The first example of a BWB design was researched at the Loughead Company in the United States of America in 1917. The Junkers G. 38, the largest land plane in the world at the time, was produced in 1929 for Luft Hansa (present day; Lufthansa). Since 1939 Northrop Aircraft Inc. (USA), currently Northrop Grumman Corporation and the Horten brothers (Germany) investigated and developed BWB aircraft for military purposes. At present, the major aircraft industries and several universities has been researching the BWB concept aircraft for civil and military activities, although the BWB design concept has not been adapted for civil transport yet. The B-2 Spirit, (produced by the Northrop Corporation) has been used in military service since the late 1980s. The BWB design seems to show greater potential for very large passenger transport aircraft. A NASA BWB research team found an 800 passenger BWB concept consumed 27 percent less fuel per passenger per flight operation than an equivalent conventional configuration (Leiebeck 2005). The purpose of this research is to assess the aerodynamic efficiency of a BWB aircraft with respect to a conventional configuration, and to identify design issues that determine the effectiveness of BWB performance as a function of aircraft payload capacity. The approach was undertaken to develop a new conceptual design of a BWB aircraft using Computational Aided Design (CAD) tools and Computational Fluid Dynamics (CFD) software. An existing high-capacity aircraft, the Airbus A380 Contents RMIT University, Australia was modelled, and its aerodynamic characteristics assessed using CFD to enable comparison with the BWB design. The BWB design had to be compatible with airports that took conventional aircraft, meaning a wingspan of not more than 80 meters for what the International Civil Aviation Organisation (ICAO) regulation calls class 7 airports (Amano 2001). From the literature review, five contentions were addressed; i. Is a BWB aircraft design more aerodynamically efficient than a conventional aircraft configuration? ii. How does the BWB compare overall with a conventional design configuration? iii. What is the trade-off between conventional designs and a BWB arrangement? iv. What mission requirements, such as payload and endurance, will a BWB design concept become attractive for? v. What are the practical issues associated with the BWB design that need to be addressed? In an aircraft multidisciplinary design environment, there are two major branches of engineering science; CFD analysis and structural analysis; which is required to commence producing an aircraft. In this research, conceptual BWB designs and CFD simulations were iterated to evaluate the aerodynamic performance of an optimal BWB design, and a theoretical calculation of structural analysis was done based on the CFD results. The following hypothesis was prompted; A BWB configuration has superior in flight performance due to a higher Lift-to-Drag (L/D) ratio, and could improve upon existing conventional aircraft, in the areas of noise emission, fuel consumption and Direct Operation Cost (DOC) on service. However, a BWB configuration needs to employ a new structural system for passenger safety procedures, such as passenger ingress/egress. The research confirmed that the BWB configuration achieves higher aerodynamic performance with an achievement of the current airport compatibility issue. The beneficial results of the BWB design were that the parasite drag was decreased and the spanwise body as a whole can generate lift. In a BWB design environment, several advanced computational techniques were required to compute a CFD simulation with the CAD model using pre-processing and CFD software.
4

Aerodynamic models for insect flight

Abdul Hamid, Mohd Faisal January 2016 (has links)
Numerical models of insect flapping flight have previously been developed and used to simulate the performance of insect flight. These models were commonly developed via Blade Element Theory, offering efficient computation, thus allowing them to be coupled with optimisation procedures for predicting optimal flight. However, the models have only been used for simulating hover flight, and often neglect the presence of the induced flow effect. Although some models account for the induced flow effect, the rapid changes of this effect on each local wing element have not been modelled. Crucially, this effect appears in both axial and radial directions, which influences the direction and magnitude of the incoming air, and hence the resulting aerodynamic forces. This thesis describes the development of flapping wing models aimed at advancing theoretical tools for simulating the optimum performance of insect flight. Two models are presented: single and tandem wing configurations for hawk moth and dragonfly, respectively. These models are designed by integrating a numerical design procedure to account for the induced flow effects. This approach facilitates the determination of the instantaneous relative velocity at any given spanwise location on the wing, following the changes of the axial and radial induced flow effects on the wing. For the dragonfly, both wings are coupled to account for the interaction of the flow, particularly the fact that the hindwing operates in the slipstream of the forewing. A heuristic optimisation procedure (particle swarming) is used to optimise the stroke or the wing kinematics at all flight conditions (hover, level, and accelerating flight). The cost function is the propulsive efficiency coupled with constraints for flight stability. The vector of the kinematic variables consists of up to 28 independent parameters (14 per wing for a dragonfly), each with a constrained range derived from the maximum available power, the flight muscle ratio, and the kinematics of real insects; this will prevent physically-unrealistic solutions of the wing motion. The model developed in this thesis accounts for the induced flow, and eliminates the dependency on the empirical translation lift coefficient. Validations are shown with numerical simulations for the hover case, and with experimental results for the forward flight case. From the results obtained, the effect of the induced velocity is found to be greatest in the middle of the stroke. The use of an optimisation process is shown to greatly improve the flapping kinematics, resulting in low power consumption in all flight conditions. In addition, a study on dragonfly flight has shown that the maximum acceleration is dependent on the size of the flight muscle.
5

Analysis, Design and Testing of a Wind Tunnel Model to Validate Fiber-Optic Shape Sensing Systems

Montero, Ryan M. 14 June 2013 (has links)
The ability to collect valuable data concerning the stress, strains, and shape profiles of aircraft and aircraft components during flight is important to fields such as structural health monitoring, gust alleviation, and flutter control. A research interest in the form of a NASA Phase I SBIR called for possible systems that would be able to take accurate shape sensing data on a flexible wing aircraft. In a joint venture between Luna Technologies Inc. and Virginia Polytechnic Institute and State University a flexible wing wind tunnel model was designed and constructed as a test article for the Luna Technologies Inc. fiber optic shape sensing system. In order to prove the capability of a fiber optic shape sensing system in a wind tunnel environment a flexible wing test article was constructed. The wing deflections and twists of the test article were modeled using a vortex lattice method called Tornado combined with simple beam theories. The beam theories were linear beam theories and the stiffness of the composite bodies was supplied by static testing of the test articles. The code was iterative in that it ran the VLM code to estimate the forces and moments on the wing and these were applied to a linear beam which gave the wing a new geometry which in turn was run through the VLM. The wind tunnel model was constructed at Virginia Tech using 3-D printing techniques for the fuselage and foam and fiberglass for the wings. On the bottom surface of the wings the Luna Technologies Inc. fiber optic shape sensing fiber was bonded along the leading and tailing edges. The swept-wing test article was experimentally tested in the Virginia Tech 6'x6' Stability Wind Tunnel at various airspeeds and the VLM based code results were in agreement, within margins of error and uncertainty, with the experimental results. The agreement of the analytical and experimental results verified the viability of using an iterative VLM code in combination with simple beam theories as a quick and relatively accurate approximation method for preliminary design and testing. The tests also showed that a fiber optic shape sensing system can be sufficiently tested in a wind tunnel environment, and if applied carefully could perhaps in the future provide useful shape and strain measurements. / Master of Science
6

Development of the wing pigmentation pattern in Lepidoptera

Toussaint, Neil January 1987 (has links)
No description available.
7

Numerical lifting surface methods for calculating the potential flow about wings and wing-bodies of arbitary geometry

Maskew, B. January 1972 (has links)
No description available.
8

The influences on optimal structural designs of the modelling processes and design concepts

Anastasiadis, P. T. January 1997 (has links)
No description available.
9

Genetic and molecular analyses of nubbin, a gene involved in proximal-distal patterning of the Drosophila wing

Ng, Medard Hein Tsoeng January 1996 (has links)
No description available.
10

Modelling and control of a symmetric flapping wing vehicle: an optimal control approach

Jackson, Justin Patrick 15 May 2009 (has links)
This thesis presents a method for designing a flapping wing stroke for a flapping wing vehicle. A flapping wing vehicle is a vehicle such as a bird or an insect that uses its wings for propulsion instead of a conventional propeller or a jet engine. The intent of this research is to design a wing stroke that the wings can follow which will maintain the vehicle at a desired longitudinal flight path angle and velocity. The cost function is primarily a function of the flight path angle error, velocity error and control rate. The objective maneuver is to achieve a flight condition similar to the trim of a conventional fixed wing aircraft. Gliding configurations of the vehicle are analyzed to better understand flight in minimal energy configurations as well as the modes of the vehicle. A control law is also designed using Lyapunov’s direct method that achieves stable tracking of the wing stroke. Results are presented that demonstrate the ability of the method to design wing strokes that can maintain the vehicle at various flight path angles and velocities. The results of this research show that an optimal control problem can be posed such that the solution of the problem results in a wing stroke that a flapping wing vehicle can use to achieve a desired maneuver. The vehicle velocity is shown to be stable in controlled gliding flight and flapping flight.

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