This diploma work considers conceptual design of aircraft in accordance in FAR 103 regulation. On the base of statistical dates has been made basic geometrical and aero-dynamical concept of a single occupant aircraft. For conception have been chosen optimal driving force and bases calculations of the load pressure and dimensions are included.

The work of this master thesis is based on analyses of monthly precipitation data from 70 stations of the SMHI (Swedish Meteorological and Hydrological Institute) in Sweden, in the period 1860-2014, using the information for the year of introduction of the wind shield at each station. The primary goal is the calculation of correction factors which will be applied on the precipitation data in the period of measurements before the introduction of the wind shield. This correction will counterbalance the underestimation of the collected precipitation by the unshielded precipitation gauges due to the effect of the wind. The wind induced error, related to aerodynamical effects, increases with increasing wind speed. The stronger the wind, the more capable it is of deflecting the precipitation water droplets or snowflakes, falling towards the gauge orifice, away from it. In spite of the important efficiency of the wind shield which acts to diminish the wind error, the long-term effect of changing the measuring instrumentation at some time in the observations history is the production of inhomogeneous data in the measurements records. Inhomogeneous precipitation data are sources of errors in climatology and hydrology and result in misleading conclusions regarding the climate change and climate variations, hence they should be identified and corrected through a homogenization method. The analysis includes the comparison of the precipitation data of each station during two periods, one before and one after the introduction of the wind shield. This comparison leads to the calculation of ratios representing the increase in the catch between the two periods due to the introduction of the wind shield. Temperature data are also processed in order to estimate the type of precipitation (snow/rain) in each case. The monthly corrections ranged between 5 %, for rain, and 27 % for snow precipitation. The absolute value of the increase of the average annual precipitation due the implementation of the correction was 50 mm. The comparison of the corrected against the uncorrected precipitation time series indicated a less pronounced increase (0.74 mm/y) of the precipitation during the last 150 years, after the application of the correction, compared to the increase indicated from the uncorrected data (1.19 mm/y). / Kontinuerliga samt felfria nederbördsmätningar är av stor betydelse för geovetenskaper som klimatologi och hydrologi därför att nederbördsdata är en av de primära meteorologiska parametrarna för forskning om klimatförändringen. Att säkerställa felfria (homogena) nederbörds tidsserier betyder i stort sett att säkerställa homogenitet genom att identifiera och korrigera inhomogena data. Icke homogena data uppkommer på grund av förändringar i mätmetoder och mätförhållanden under observationstiden, sedan 1860-talet tills idag alltså. Denna studies syfte är att beräkna en korrektion som ska användas för att korrigera nederbördsmätningar som utfördes sedan 1860 utan vinskydd. Vindskyddet eller vindskärmen, en speciell utrustning som användas på nederbördsinsamlare, infördes gradvis under perioden 1900-1960 vid de svenska nederbördstationerna. Vindskyddet introducerades med avsikt att minska vindens påverka vid nederbördsinsamling. Men trotts den positiva effekten som vindskyddet ledde till, genom den ökade nederbördsmängden som samlades in, skapade denna förändring av mätarutrustningen inhomogena data. Bearbetningen skedde för månadsnederbördsdata från 70 stationer från SMHIs meteorologiska nätverk genom att jämföra nederbördsobservationer som genomfördes under perioderna tio år före och tio år efter införandet av vindskydd. Dessutom användes temperaturdata från samma stationer för att uppskatta nederbördslag (snö/regn). Skälet till detta är att vinskyddseffekten är olika mellan snö och regn. Beräkningarna och bestämningen av nederbördslag ledde till en 5 % respektive 27 % nederbörds ökning för regn och snö för de mätningarna som utfördes utan vindskydd. I genomsnitt har de korrigerade värdena, under perioden som vinskyddet saknades, ökat med omkring 50 mm.

<p>Train transportation is a vital part of the transportation system of today anddue to its safe and environmental friendly concept it will be even more impor-tant in the future. The speeds of trains have increased continuously and withhigher speeds the aerodynamic effects become even more important. One aero-dynamic effect that is of vital importance for passengers’ and track workers’safety is slipstream, i.e. the flow that is dragged by the train. Earlier ex-perimental studies have found that for high-speed passenger trains the largestslipstream velocities occur in the wake. Therefore the work in this thesis isdevoted to wake flows. First a test case, a surface-mounted cube, is simulatedto test the analysis methodology that is later applied to a train geometry, theAerodynamic Train Model (ATM). Results on both geometries are comparedwith other studies, which are either numerical or experimental. The comparisonfor the cube between simulated results and other studies is satisfactory, whiledue to a trip wire in the experiment the results for the ATM do not match.The computed flow fields are used to compute the POD and Koopman modes.For the cube this is done in two regions of the flow, one to compare with a priorpublished study Manhart & Wengle (1993) and another covering more of theflow and especially the wake of the cube. For the ATM, a region containing theimportant flow structures is identified in the wake, by looking at instantaneousand fluctuating velocities. To ensure converged POD modes two methods toinvestigate the convergence are proposed, tested and applied. Analysis of themodes enables the identification of the important flow structures. The flowtopologies of the two geometries are very different and the flow structures arealso different, but the same methodology can be applied in both cases. For thesurface-mounted cube, three groups of flow structures are found. First groupis the mean flow and then two kinds of perturbations around the mean flow.The first perturbation is at the edge of the wake, relating to the shear layerbetween the free stream and the disturbed flow. The second perturbation isinside the wake and is the convection of vortices. These groups would then betypical of the separation bubble that exists in the wake of the cube. For theATM the main flow topology consists of two counter rotating vortices. Thiscan be seen in the decomposed modes, which, except for the mean flow, almostonly contain flow structures relating to these vortices.</p> / QC 20100518 / Gröna Tåget

<p>The continuous trend in gas turbine design towards lighter, more powerful and more reliable engines on one side and use of alternative fuels on the other side renders flutter problems as one of the paramount challenges in engine design. Flutter denotes a self-excited and self-sustained aeroelastic instability phenomenon that can lead to material fatigue and eventually damage of structure in a short period of time unless properly damped. The design for flutter safety involves the prediction of unsteady aerodynamics as well as structural dynamics that is mostly based on in-house developed numerical tools. While high confidence has been gained on the structural side unanticipated flutter occurrences during engine design, testing and operation evidence a need for enhanced validation of aerodynamic models despite the degree of sophistication attained. The continuous development of these models can only be based on the deepened understanding of underlying physical mechanisms from test data.</p><p>As a matter of fact most flutter test cases treat the turbomachine flow in two-dimensional manner indicating that the problem is solved as plane representation at a certain radius rather than representing the complex annular geometry of a real engine. Such considerations do consequently not capture effects that are due to variations in the third dimension, i.e. in radial direction. In this light the present thesis has been formulated to study three-dimensional effects during flutter in the annular environment of a low-pressure turbine blade row and to describe the importance on prediction of flutter stability. The work has been conceived as compound experimental and computational work employing a new annular sector cascade test facility. The aeroelastic response phenomenon is studied in the influence coefficient domain having one blade oscillating in various three-dimensional rigid-body modes and measuring the unsteady response on several blades and at various radial positions. On the computational side a state-of-the-art industrial numerical prediction tool has been used that allowed for two-dimensional and three-dimensional linearized unsteady Euler analyses.</p><p>The results suggest that considerable three-dimensional effects are present, which are harming prediction accuracy for flutter stability when employing a two-dimensional plane model. These effects are mainly apparent as radial gradient in unsteady response magnitude from tip to hub indicating that the sections closer to the hub experience higher aeroelastic response than their equivalent plane representatives. Other effects are due to turbomachinery-typical three-dimensional flow features such as hub endwall and tip leakage vortices, which considerably affect aeroelastic prediction accuracy. Both effects are of the same order of magnitude as effects of design parameters such as reduced frequency, flow velocity level and incidence. Although the overall behavior is captured fairly well when using two-dimensional simulations notable improvement has been demonstrated when modeling fully three-dimensional and including tip clearance.</p>

Modern volume carriers such as container vessels, cruise ships and Pure Car and Truck Carriers (PCTC’s) have become more vulnerable to critical roll responses as built in margins have been traded against increased transport efficiency. The research presented in this doctoral thesis aims at enhancing the predictability and control of these critical roll responses. The thesis presents a holistic framework for predicting and assessing the roll damping, which is a crucial parameter for predicting roll motions, based on a unique combination of full scale trials, model tests, semi-empirical methods and computational fluid dynamics. The framework is intended to be used from the early design stage and gradually improved until delivery of the ship and finally to provide input for decision support in the operation. The thesis also includes a demonstration of a new application for rudder control to be used for mitigation of parametric roll. This is performed by simulating real incidents that have occurred with PCTC’s in service. Simulations with rudder roll control show promising results and reveal that the approach could be very efficient for mitigation of parametric roll. Finally, an approach for monitoring of roll induced stresses, so-called racking stresses in PCTC’s, is presented. The approach involves measurement of the ship motions and scaling of pre-calculated structural responses from global finite element analysis. Based on full scale motion and stress measurements from a PCTC in-service the approach is evaluated and demonstrated to be an efficient alternative to conventional methods. / <p>QC 20170516</p>

Ce sujet de thèse s'intéresse à l'étude des effets des charges aérodynamiques sur le comportement dynamique non linéaire d'une éolienne à axe vertical de type Darrieus. Cette dernière présente, comparativement aux autres éoliennes, des profits très importants à exploiter, notamment dans les milieux urbains. Il s'agit d'une technologie fiable caractérisée surtout par son fonctionnement omnidirectionnel ainsi que son adaptation à tout type de vent. Généralement, ces éoliennes, ayant des phénomènes aérodynamiques complexes, sont affectées par des vibrations au niveau de leur système de transmission de puissance. En fait, ces vibrations commencent à se manifester à partir des pales du rotor jusqu'au génératrice. L'écoulement autour de ses pales présente également un fort caractère instationnaire. Cette caractéristique augmente d'avantage les vibrations aérodynamiques, qui sont automatiquement transmise au système d'engrenage d'éolienne. À ce niveau, nous avons développé un code de calcul numérique permettant de simuler la complexité des aspects aérodynamiques instationnaires tout en gardant un compromis entre la fiabilité des prédictions et la rapidité de calcul. Les simulations sont réalisées suivant une méthode de mécanique des fluides numérique (CFD) instationnaire bidimensionnel. Les résultats de simulation comparés avec ceux disponibles dans la littérature sont en bonne concordance, le rendement aérodynamique étant optimisé, qui présente un apport scientifique notable. Cette étude numérique a été l'objectif de l'analyse de l'impact des charges aérodynamiques vis-à-vis le comportement dynamique du système d'engrenage de l'éolienne en régime non-stationnaire. Dans ce contexte, une étude paramétrique a été développée afin d'établir le fonctionnement optimal de l'éolienne, caractérisé par un couple aérodynamique plus performant associé à des niveaux de vibrations dynamiques acceptables. En général, il est difficile d'identifier précisément la réponse dynamique des éoliennes à cause du caractère turbulent et stochastique des charges aérodynamiques. Par conséquent, il est indispensable de tenir en compte la variabilité des paramètres d'entrée pour assurer la robustesse du système étudié. Adoptons l'objectif de dimensionnement robuste. Une méthode d'évaluation basée sur des approches stochastiques, particulièrement la méthode du Chaos Polynomial, est utilisée pour simuler le comportement dynamique non-linéaire du système d'engrenage d'éolienne, en tenant compte des incertitudes. Ces dernières sont au niveau des charges aérodynamiques, inhérentes au calcul des niveaux vibratoires du système d'engrenage. Ce qui implique un apport scientifique important. Les résultats obtenus par l'approximation par Chaos Polynomial démontrent une forte dispersion des charges aérodynamiques aléatoires dans la réponse dynamique du système d'engrenage, contrairement aux études déterministes. Ce qui prouve l'insuffisance de telles études pour une analyse de robustesse. Les résultats mettent également en évidence la forte corrélation entre les phénomènes aérodynamiques complexes et les vibrations dynamiques. Le couplage établi constitue l'originalité de notre travail. / This thesis focuses on the study of the aerodynamic loads effects on the nonlinear dynamic behavior of Darrieus--type vertical axis wind turbine. The latter has received more attention due to its efficiency in urban regions compared to other wind turbines. In fact, the wind flow speed in urban regions continuously changes direction and is extremely turbulent. The inherent characteristics of its omni-directionality make it more suitable to harnessing this kind of flow. It is known that Darrieus wind turbine is characterized by an inherently unsteady aerodynamic behavior and a complex flow around rotor blades. The non-stationary behavior of the mentioned turbine increases vibration. These aerodynamic vibrations are transmitted to the gearing mechanism. We have, firstly, developed a numerical simulation, allowing to simulate the complexity of the unsteady aerodynamic phenomena keeping a compromise between the reliability of prediction and the rapidity of calculation. This numerical simulation has been carried out using a two-dimensional unsteady Computational Fluid Dynamics (CFD) method. Simulation results compared to those available in the literature are in good agreement. The Darrieus turbine efficiency is also optimized; thus introducing a significant scientific contribution. The latter is the objective of analyzing the aerodynamic load impact in the dynamic behavior of the Darrieus turbine in non-stationary regime. In this context, a parametric study has been developed in order to find optimal functioning of the studied turbine, which is characterized by the most performing aerodynamic torque associated with acceptable levels of dynamic vibration. In general, it is difficult to predict the dynamic response of the wind turbine with a good level of accuracy due to the aerodynamic loads turbulence and uncertain characteristics. It becomes necessary to take into account the uncertainty in the input parameters to ensure the robustness of the Darrieus turbine geared system. In a robustness study objective, the Polynomial Chaos method is adopted to predict the nonlinear dynamic behavior of the gearing system taking into account uncertainties which are associated to the performance coefficient of the input aerodynamic torque. This leads to an important scientific research contribution. The results have shown a large dispersion of the random parameter in the dynamic response of the gearing system compared to the deterministic study. That proves the insufficiency of that study for a robustness analyses. They have also proved that the Polynomial Chaos method is an efficient probabilistic tool for uncertainty propagation. Finally, the new proposed robust mechanical analysis indicates a good capacity to investigate the dynamic behavior of the Darrieus turbine thanks to its superior predictive capabilities in coupling complex aerodynamic phenomena with a mechanical gearing system vibration. Where the originality of such correlation in our work.

Aircraft system identification has been widely used to this day in applications like control law design, building simulators or extending flight envelopes. It can also be utilized for determining flight-mechanical characteristics in the preliminary design phase of a flight vehicle. In this thesis, three common time-domain methods were implemented in MATLAB for determining the aerodynamic derivatives of a subscale aircraft. For parameter estimation, the equation-error method is quick, robust and can provide good parameter estimates on its own. The output-error method is computationally intensive but keeps account of the aircraft's evolution in time, being more suitable for fine-tuning predictive models. A new model structure is identified using multivariate orthogonal functions with a predicted squared error stopping criteria. This method is based on linear regression (equation-error). The code written is flexible and can also be used for other aircraft and with other aerodynamic models. Simulations are compared with experimental data from a previous flight test campaign for validation. In the future, this tool may help taking decisions in conceptual design after a prototype is tested.

Dois dos principais objetivos no estudo da aerodinâmica de veículos comerciais são a redução no consumo de combustível e o aumento na eficiência da refrigeração do motor. Esses objetivos podem ser alcançados através do desenvolvimento de dispositivos que modifiquem o escoamento do ar ao redor do veículo e também através da alteração da forma das superfícies externas. A inclinação das superfícies da parte traseira de um ônibus, por exemplo, tem grande influência sobre a esteira turbulenta que se forma atrás do veículo. O uso de ferramentas computacionais permite uma redução de custo e maior flexibilidade na análise aerodinâmica de autoveículos. Ainda é preciso, no entanto, que o resultado dessas ferramentas computacionais seja verificado com o maior número possível de casos para que se possa escolher e ajustar o modelo matemático de forma adequada. O objetivo do presente trabalho é a verificação dos resultados computacionais e experimentais no desenvolvimento de metodologias que visem à redução no consumo de combustível e aumento na eficiência da refrigeração do motor. Foram comparados resultados experimentais e computacionais do escoamento sobre um modelo de um ônibus comercial em escala 1:17,5. Para a realização do experimento foi utilizado um túnel de vento de seção aberta, onde foram analisadas as distribuições de pressão nas superfícies da carroceria e o arrasto aerodinâmico. Para o teste computacional, foi utilizado um software de dinâmica dos fluidos computacional em que as equações de Navier-Stokes com média de Reynolds são resolvidas pelo método dos volumes finitos usando um modelo de turbulência RNG 'capa' - 'épsilon' / Two main objectives in the study of commercial vehicle aerodynamics are the reduction in fuel consumption and the improvement in engine refrigeration efficiency. These objectives can be achieved through development of devices which vary the flow characteristics around the vehicle and also through modification of the shape of external surfaces. The slope of rear surfaces, for instance, has large influence over the wake turbulence which forms behind the vehicle. The use of computational tools yields cost reduction and greater flexibility in automotive aerodynamic analysis. There is still a need, however, for verification of results, generated by these computational tools, with the largest possible number of test cases so that the mathematical model is adequately chosen and adjusted. The objective of the present work is the verification of experimental and computational results in the development of methodologies aiming at reduction of fuel consumption and improvement in engine refrigeration efficiency. Experimental and computational aerodynamic results were compared for a commercial bus model with a 1:17.5 scale. The experiments were conducted in an open section wind tunnel where pressure distribution and aerodynamic drag were analyzed. The numerical analysis was conducted using computational fluid dynamics software which solves the Reynolds Averaged Navier-Stokes equations using the finite volume method with a RNG 'capa' - 'épsilon' turbulence model

L'utilisation des coefficients aérodynamiques pour caractériser le comportement d'un objet en vol libre demeure un sujet de recherche parmi les plus complexes et les plus étudiés dans le domaine de la balistique extérieure. La présente étude analyse l'identification des coefficients aérodynamiques à partir de données obtenues lors d'essais en vol libre. Elle vise à modéliser, définir ainsi que maîtriser les techniques d'identification de paramètres les plus adaptées au problème qu'est la détermination des coefficients aérodynamiques. Le travail de thèse a été dédié au développement d'une procédure d'identification pour la détermination des coefficients aérodynamiques à partir de mesures de vol libre et a été testée pour deux cas d'application : un corps de rentrée dans l'atmosphère et un projectile stabilisé par empennage. Cette procédure nécessite plusieurs étapes telles que la description du comportement d'un objet en vol libre sous la forme d'un modèle non linéaire en représentation d'état, la description polynomiale des coefficients aérodynamiques en fonction du nombre de Mach et de l'incidence, les analyses d'identifiabilité a priori et a posteriori suivies de l'estimation des paramètres. De plus, dans le but d'augmenter la probabilité que les coefficients caractérisent l'aérodynamique de l'objet pour l'ensemble des conditions d'essais et d'améliorer la précision des coefficients estimés, une stratégie "multiple fit" a été appliquée. Cette approche fournit une base de données de coefficients aérodynamiques, qui sont déterminés à partir de plusieurs séries de mesures analysées simultanément, afin de décrire le spectre le plus complet du mouvement de l'objet / The use of aerodynamic coefficients for the characterization of the behaviour of an object in flight remains one of the oldest and most emergent research project in the field of exterior ballistic. The present study investigates the identification of the aerodynamic coefficients based on measured data, gathered during free flight tests from different measurement techniques. This project deals with topics as modelling, defining and mastering parameter identification techniques best suited to the problem of the aerodynamic coefficients determination. In the frame of this study, an identification procedure was developed for the aerodynamic coefficients determination based on free flight measurements and was tested for two application cases: a re-entry space vehicle and a fin stabilized reference projectile. This procedure requires several steps such as the description of the behaviour of the vehicle in free flight as a nonlinear state-space model representation, the polynomial descriptions of the aerodynamic coefficients as function of Mach number and incidence, the a priori and a posteriori identifiability analyses, followed by the estimation of the parameters from free flight measurements. Moreover, to increase the probability that the coefficients define the vehicle’s aerodynamics over the entire range of test conditions and to improve the accuracy of the estimated coefficients, a multiple fit strategy was considered. This approach provides a common set of aerodynamic coefficients that are determined from multiple data series simultaneously analyzed, and gives a more complete spectrum of the vehicle’s motion

Esse trabalho descreve uma investigação prática e teórica de características aerodinâmicas de um modelo referente a um avião bimotor leve \"Piper PA-34 SENECA III\" construído em escala 1:6,5. Basicamente, duas configurações fazem parte da avaliação: \"asa limpa\" e Nacele \"Pusher\". O principal objetivo é o de avaliar o comportamento aerodinâmico da configuração \"Pusher\" em três diferentes posições através da obtenção de dados práticos e teóricos de distribuição de pressão estática no aerofólio e no próprio nacele na condição não motorizada. A metodologia emprega testes em túnel de vento de baixa velocidade para a aquisição dos dados experimentais através da variação do ângulo de ataque para as configurações citadas. A obtenção dos dados numéricos, como comparativos aos experimentais, é através da utilização do método dos painéis aplicado à aerodinâmica. Os resultados experimentais e teóricos mostram que a presença do nacele nas posições \"Pusher\" avaliadas gera interferência diminuindo à sustentação do aerofólio. / This work describes a practical and theoretical investigation of aerodynamic characteristics of a 1:6,5 scale model of a light twin-engined Piper Seneca III aircraft. Basically, two configurations are considered in this evaluation: clean wing and pusher nacelle. The principal objective is to evaluate the aerodynamic characteristics of the pusher configuration in three different positions, in order to obtain practical and theoretical data with reference to static pressure distribution on the surface of the aerofoil and of the nacelle in a power-off condition. The methodology employed used low speed wind tunnel test for the acquisition of experimental data for a selection of angles of attach, as cited. The generation of numerical data, to be compared the experimental equivalent, is though the use of a low order panel method. The experimental and theoretical results show that the presence of pusher nacelle in the positions mentioned generated interference, reducing the local lift of the aerofoil.