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New airfoil designs are created in order to improve both the structural and aerodynamic properties of a wind turbine blade, one example of these are flatback airfoils. Furthermore, a new CFD programme exists in order to study the behavior of the flow around an airfoil, OpenFOAM. The flow around these new airfoils using OpenFOAM is studied in the present thesis. It is used the turbulence model k-! SST for fully turbulent boundary layer and free transition at the boundary layer, modeled with the Re t− transition model. At the beginning of the present thesis the programme OpenFOAM is validated by doing different sensitivity studies on a thin airfoil (NACA0012) and then it is validated by comparing results obtained ANSYS CFX, Ellipsys and wind tunnel experiments. It is seen good agreement of OpenFOAM’s results with these other results just mentioned. It is seen that, making flatback airfoils which are very thick (with a relative thickness of 48 % and 57 %) by opening the trailing edge thickness the same percentage towards both pressure and suction side, much better aerodynamic characteristics are obtained. For example, while thickening the trailing edge of one airfoil 20 %, the lift coefficient is increasing 180 % and the lift-to-drag ratio 140 % for the range they are supposed to operate. While making flatback airfoils that are 35 % and 36 % thick relative to the chord, this increment in the lift-to-drag ratio is not observed. The behavior of the flow around a flatback airfoil is studied by increasing its chord into the dead water zone created behind the airfoil. The same pressure distribution on the wall of the modified versions is observed as for the former flatback airfoils. The friction coefficient is also very similar. Thus, the flatback airfoils studied with OpenFOAM are profitable for the inner sections of the blade of a wind turbine, where very thick airfoils are found. Outgoing

© 2017 Elsevier LtdTwo pelagic otterboards, previously tested in a wind tunnel, have been tested in a flume tank prior to their analysis in real working conditions in sea trials. This intermediate step aims at providing guidance for sea trial planning and a basis for otter board performance analysis from real campaign data. The doors were rigged in working-like conditions in the flume tank, with onboard-mounted attitude sensors to provide at the same time a noisy environment as expected in sea trials and accurate measurement of all quantities relevant to precise determination of hydrodynamic angles and forces. The trends found in flume tank experiments closely match wind tunnel results, although systematic offset has been observed that can be ascribed to deviations between nominal and real water velocity, due to inhomogeneous velocity distribution in the cross-section.

El objetivo principal del trabajo consiste en la optimización de la geometría general de un tipo específico de aeronaves, los Flying Wings. Estas aeronaves difieren del concepto de avión actual, por la inexistencia de un cuerpo cilíndrico y de cola. Por este motivo, los Flying Wings reciben su nombre, ya que se asemejan a una única ala en vuelo. Para la optimización han sido utilizadas técnicas DFC (Dinámica de Fluidos Computacional), permitiendo simular diversas geometrías en diferentes condiciones de vuelo. Primero se explica el concepto e idea de los Flying Wing y las técnicas DFC. Incluyendo algunos conceptos de aerodinámica que facilitarán el entendimiento del trabajo. Para la simulación de cualquier geometría es necesario un proceso de creación, el cual está explicado detalladamente. La forma más conveniente y más lógica de optimizar un Flying Wing, consiste en la creación de varias geometrías diferentes, para escoger una como la geometría óptima. Así, posteriormente, se utiliza esta geometría optimizada, para aplicar cambios sobre ella, intentando mejorarla. Estos cambios consisten en variar el diedro y la flecha de la aeronave, así como añadir un winglet y redondear la forma de la geometría. Por último se analiza la geometría optimizada, para poder observar la distribución de presiones de la misma.

En el món de la competició, cada vegada és més important aconseguir les millors prestacions aerodinàmiques possibles. Aquest fet queda demostrat al comprovar que en els darrers anys els equips que han invertit més temps a estudiar i millorar l’aerodinàmica del seu monoplaça són els que obtenen millors resultats. Aquest estudi sorgeix de la idea d’estudiar el comportament aerodinàmic del fons pla d’un Formula Renault 3.5. Aquest és el monoplaça utilitzat per Pons Racing en la competició World Series by Renault. El principal objectiu és realitzar aquest estudi mitjançant tècniques de dinàmica de fluids computacional. Concretament es pretén calcular les forces que actuen sobre el fons pla segons la posició i la inclinació en què aquest es trobi respecte el terra. Per fer-ho, s’utilitza el paquet Ansys-Fluent 13.0, amb el qual es crea la geometria a estudiar, es diferencien tres posicions del fons pla, es fa la simulació numèrica per cadascuna d’aquestes tres i se n’obtenen els resultats corresponents. Amb aquests resultats es fa una comparació gràfica i numèrica per tal d’extreure’n unes conclusions. El treball està dividit en tres grans blocs. El primer bloc té com a finalitat explicar tota la teoria necessària per comprendre bé l’estudi. En el segon bloc, s’estudia el fons pla del Formula Renault 3.5. I en l’últim bloc es mostren i discuteixen els resultats obtinguts.Com a conclusions del treball, es pot extreure que, a més proximitat del terra, més downforce es genera però, com a conseqüència, també es crea més resistència. Per tant, no hi ha una relació downforce-resistència òptima sinó que cada configuració proporciona una sèrie d’avantatges i inconvenients. És per això que sempre s’ha d’arribar a una situació de compromís segons les condicions de la carrera en què s’està.

Presentemente, para se efetuar expedições a locais mais remotos no continente da Antártida, os cientistas utilizam tendas como abrigo. As tendas, embora sendo portáteis e de fácil montagem, têm dificuldades em resistir às condições agrestes do ambiente antártico. Para tal, a presente dissertação procura conceber um protótipo, que mais adequadamente poderá proteger e alojar os investigadores nas suas missões científicas neste continente gelado, mantendo sempre o foco na sua portabilidade e sustentabilidade. A dissertação parte, numa primeira fase, por uma investigação sobre o continente. A investigação procura deste modo compreender a sua morfologia, a sua importância para com a nossa espécie e para com o planeta e por fim as suas fragilidades ambientais. Posteriormente analisa-se como foi desenvolvida a base móvel no continente antártico, inspirada na habitação yurt, realizada no âmbito do projeto POLAR LODGE, referente ao Programa Polar Português (PROPOLAR). É apresentada similarmente uma pesquisa de outros casos de estudo em situações díspares, dimensionamentos mínimos e novos materiais indissociáveis à sustentabilidade e às condições do continente da Antártida. De igual modo procura-se entender como se comportam os corpos perante o deslocamento do fluxo de ar ou seja, a aerodinâmica, como forma de compreender quais os requisitos de projeto que permitam garantir resistência a ventos de grande intensidade. Por fim, numa segunda fase, com base nas pesquisas acima referidas, é concebido e apresentado o protótipo final, juntamente com as ideias de constituição, montagem e diferentes abordagens. Nowadays, when performing expeditions to the most remote places in Antarctica, scientists typically use tents as shelters. These tents, albeit being very portable and easy to assemble, lack the structural stability to withstand the harsh conditions of the Antarctic environment. Therefore, this thesis pursues to conceive a novel shelter prototype that, more adequately, protects and lodges the researchers in their scientific missions in this icy continent, all the while maintaining a focus on portability and sustainability. In a first stage, a research about the Antarctic continent is presented. This research comprehends its morphology, its significance to our species and planet, and, in the end, its environmental fragilities. Secondly, a mobile base, inspired by a yurt, conceived within the framework of POLAR LODGE (a subproject of the Portuguese Polar Program), is analysed. Similarly, other case studies are presented and discussed in dissimilar situations, together with a research about minimal dimensions, new materials and sustainable issues, intrinsic to the inhospitable conditions of the Antarctic territory. The thesis then focuses on a brief review on aerodynamics, seeking to comprehend the interaction of shapes and air flow, so that the design performance requirements related to strong winds are better understood. Finally, in a second stage, based on the previous researche, the final prototype is conceived and presented alongside a brief discussion of its constitution and assembly methods and techniques.

Els avions de la Segona Guerra Mundial sempre m’han despertat certa curiositat, així que comentant temes per al treball de fi de grau, va sorgir la idea de l’estudi de perfils, i la meva reacció va ser estudiar el perfil del mític avió Supermarine Spitfire. Aquest va ser un avió emergent a Anglaterra i que va desenvolupar un gran paper durant la dècada de 1940 i els anys posteriors. Un altre factor que hem va fer elegir aquest tema, va ser que un cop completades totes les assignatures de la titulació, la part de simulació realitzada a l’assignatura de Mecànica de fluids hem va parèixer interessant, i hem vaig quedar amb ganes d’aprendre més sobre aquesta part. Així, la realització d’aquest treball, hem permet posar en pràctica i continuar aprenent sobre el món de les simulacions, i a més a més, amb un tema que sempre m’ha despertat curiositat. Aquest treball es pot dividir en tres parts diferenciades, primerament es realitza un estudi aerodinàmic del perfil d’ala utilitzat en la construcció de l’avió Spitfire, en el qual s’introdueixen tots els resultats obtinguts mitjançant el Fluent. A continuació, hi ha un contrast entre 4 tipus de perfils que podrien millorar les prestacions de l’avió, i es comenten les principals característiques de cadascun a partir de les dades proporcionades pel programa Visual Foil. Finalment, es realitza un estudi final del perfil elegit per a la millora del perfil original de l’Spitfire, i hi ha una comparativa entre els dos. Per tant ,l’abast del projecte es limita a l’estudi de diferents perfils ja existents, l’obtenció dels seus paràmetres òptims, i el posterior estudi i comparació mitjançant el Fluent entre el perfil original i el proposat per a la millora. No s’indagarà sobre aspectes que puguin variar com a conseqüència de la variació d’aquest perfil en l’avió.

The project consists in solve specific technical problems and design different structural subsystems such as windows , a proper entry and the pressurization system for a semi - built manned stratospheric balloon capsule. It has also been designed a test experiment to verify the security and technical feasibility of the main elements. D ealing with suppliers and designing pre - launch procedures will be also studied in order to ease the implementation stage . This is a real project carried out by Zero2infinity SL, a private company that develops Near - Space technologies.

We investigate the aerodynamic performance of active flow control of airfoils and wings using synthetic jets with zero net-mass flow. The study is conducted via wall-resolved and wall-modeled large-eddy simulation using two independent CFD solvers: Alya, a finite-element- based solver; and charLES, a finite-volume-based solver. Our approach is first validated in a NACA4412, for which numerical and experimental results are already available in the literature. The performance of synthetic jets is evaluated for two flow configurations: a SD7003 airfoil at moderate Reynolds number with laminar separation bubble, which is representative of Micro Air Vehicles, and the high-lift configuration of the JAXA Standard Model at realistic Reynolds numbers for landing. In both cases, our predictions indicate that, at high angles of attack, the control successfully eliminates the laminar/turbulent recirculations located downstream the actuator, which increases the aerodynamic performance. Our efforts illustrate the technology- readiness of large-eddy simulation in the design of control strategies for real-world external aerodynamic applications. This work is funded in part by the Coturb program of the European Research Council. O. L. acknowledges the financial support by the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación, Spain (ref. TRA2017-88508-R) and the European Union’s Horizon 2020 research and innovation programme (INFRAEDI-02-2018, EXCELLERAT- The European Centre Of Excellence For Engineering Applications H2020.). We also acknowledge Red Española de Supercomputación and Barcelona Supercomputing Center for awarding us access to the MareNostrum IV machine based in Barcelona, Spain (FI-2018-3- 0021, FI-2018-2-0015, FI-2018-1-0022, FI-2017-3-0024). We acknowledge Prof. R. Vinuesa for the discussions and data analysis of the NACA4412. A.L.-D. acknowledges the support of NASA Transformative Aeronautics Concepts Program (Grant No. NNX15AU93A) and the Office of Naval Research (Grant No. N000141712310).