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1
BACCHINI, ALESSANDRO. "Electric VTOL preliminary design and wind tunnel tests." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2847140.
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Frison, Giovanni. "Aeroelastic and aerodynamic wind tunnel tests for tall buildings." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3423186.
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Starting from the consolidated concept of aerodynamic model, a benchmark is proposed to further asses an extend its capability of correctly identify the dynamic response of a tall building, devoting particular attention to the contribution of higher-order modes and the possible presence of aerodynamic damping. Being the extrema ratio in terms of accuracy and reliability, a full-aeroelastic model of a tall building is presented as the subject of comparison. The complexity involved in the dynamic wind-tunnel scaling led to the definition of a novel semi-automatized procedure. Based on the author’s experience, developed during the project, each step comes with practical advice, often challenging to find in the scientific literature, and food for thought on the worthiness of design-oriented aeroelastic modeling approach. The design, construction, identification, and validation of a 1:360-scale, a four-level lumped-mass aeroelastic model of the well-known Caarc standard tall building, is presented. Differently to the numerous previous research involving the Caarc building, here it is disclosed in a new guise, featuring torsional and second-order modes, enhancing the challenge for the aerodynamic model test. An extensive experimental campaign is performed at the CRIACIV boundary layer wind tunnel. Tests are performed in turbulent flow for a wide range of velocities and varying the structural damping to be able to address the results for different design criteria. Although the aerodynamic model is generally found to provide useful insight in the building response, the presence of aerodynamic damping and second-order modes are found to be relevant both in terms of base moments and acceleration. From a design perspective, even for "not exceptional" tall buildings, such as the Caarc, the aerodynamic model seems a valid option for early design stages, while the adoption of an aeroelastic model might be a valuable solution in the refinement of loads or serviceability criteria.
3
Warsido, Workamaw Paulos. "Reducing Uncertainties in Estimation of Wind Effects on Tall Buildings Using Aerodynamic Wind Tunnel Tests." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/939.
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Tall buildings are wind-sensitive structures and could experience high wind-induced effects. Aerodynamic boundary layer wind tunnel testing has been the most commonly used method for estimating wind effects on tall buildings. Design wind effects on tall buildings are estimated through analytical processing of the data obtained from aerodynamic wind tunnel tests. Even though it is widely agreed that the data obtained from wind tunnel testing is fairly reliable the post-test analytical procedures are still argued to have remarkable uncertainties. This research work attempted to assess the uncertainties occurring at different stages of the post-test analytical procedures in detail and suggest improved techniques for reducing the uncertainties.
Results of the study showed that traditionally used simplifying approximations, particularly in the frequency domain approach, could cause significant uncertainties in estimating aerodynamic wind-induced responses. Based on identified shortcomings, a more accurate dual aerodynamic data analysis framework which works in the frequency and time domains was developed. The comprehensive analysis framework allows estimating modal, resultant and peak values of various wind-induced responses of a tall building more accurately.
Estimating design wind effects on tall buildings also requires synthesizing the wind tunnel data with local climatological data of the study site. A novel copula based approach was developed for accurately synthesizing aerodynamic and climatological data up on investigating the causes of significant uncertainties in currently used synthesizing techniques. Improvement of the new approach over the existing techniques was also illustrated with a case study on a 50 story building.
At last, a practical dynamic optimization approach was suggested for tuning structural properties of tall buildings towards attaining optimum performance against wind loads with less number of design iterations.
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Meszaros, Steven P. "Wind tunnel tests to determine effective leakage area in model grain bins." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/MQ32189.pdf.
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Lehmkuehler, Kai. "A Direct Comparison of Small Aircraft Dynamics between Wind Tunnel and Flight Tests." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16511.
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The miniaturization of embedded electronics and sensors driven by the rapid development of mobile devices has enabled powerful avionics systems for very small aircraft. This enables a potential step forward in accurate flight data gathering for vehicles weighing 5 kg or less. Being able to flight test a small platform like this also allows the comparison of the results with reference data from ground testing in a standard sized wind tunnel of an identical airframe. With this process, the following questions can be answered: Firstly, would such a system then be able to collect accurate flight data for system identification (ID)? Is it possible at all to fly a small, remotely piloted aircraft precisely enough to record the required data, given its sensitivity to atmospheric turbulence, airframe noise, limitations of the remote piloting and so on? And secondly, if accurate data has been obtained, how well do the two experiments match? The small scale might potentially result in previously unknown or at least insignificant physical phenomena, which need to be taken into account when flight testing such a small platform. The changes in the inertial properties of the platform due to the added mass effect is one of these phenomena, which can typically be ignored for full scale aircraft. However, this has proven to be critically important for the successful analysis and comparison of the flight- and wind tunnel data obtained throughout this project. The avionics suite designed for this research was developed in house, since the weight restrictions of the small platform excluded any commercially available flight data recording packages. The suite features an lightweight airdata probe, control surface feedback sensors, a custom designed GPS receiver and many other advanced components previously not possible at this scale. A commercial reference INS was used to benchmark the system. The UAVmainframe also provides basic flight control functionality to aid the pilot in obtaining the required trim conditions and turbulence mitigation. Extensive data compatibility analysis and calibrations were performed on the recorded data using an Extended Kalman Filter (EKF) and various other methods to ensure the best possible data quality. The inertial properties of the test aircraft were determined by swing tests. The significance of the added mass contributions was discovered during these tests, which added up to 25% onto the `true' airframe inertial properties. In an effort to estimate these added mass terms, it has been found that the methods presented in literature to determine the corrections for full scale aircraft do not give the correct results for the small scale aircraft under consideration. Swing tests of a flat plate model of the test aircraft also did not capture the magnitude of the phenomenon correctly, which led to swing tests with a geometrically similar 3-d object of known inertial properties to successfully estimate the added mass corrections. Static derivatives were obtained from conventional wind tunnel testing, in conjunction with a high fidelity three dimensional inviscid solution using the PanAir code. A dynamic test rig was used in the wind tunnel to determine the dynamic derivatives. It allowed the instrumented airframe to rotate freely on a three axis gimbal, essentially 'fly' in the tunnel. The aerodynamic derivatives from these 3 DoF tests were estimated by performing system ID on the recorded data, where the model structures were modified for the reduced set of motion variables. Extensive flight testing was performed at the university's flight test centre. These tests showed the difficulty of testing such a small and light airframe due to wind and airframe noise, as well as the limitations due to lack of feedback received by the remote pilot. The pilot was aided by the flight control system to achieve a good trim condition, and pre-recorded input sequences, similar to the dynamic wind tunnel tests, were used to excite the longitudinal and lateral dynamics of the aircraft. One particular finding during the test campaign was that there is no such thing as totally calm conditions for this scale of airframe. Other findings include a high correlation between the pitch damping term and the pitching moment due to elevator, making it impossible to determine both at the same time, and that in flight the inertial properties of the test aircraft change to the values that include the added mass components, as compared to the dynamic wind tunnel tests, where the `true' inertias are used. By including these findings in the data processing, close agreement between flight and ground test data has been achieved.
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Kusmarwanto, I. "Ground effect on a rotor wake." Thesis, Cranfield University, 1985. http://dspace.lib.cranfield.ac.uk/handle/1826/4545.
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The effect of the ground on a rotor wake in
forward flight has been investigated experimentally in the
working section of an 8ft x Oft straight-through wind
tunnel. A three bladed fully articulated rotor with a
solidity ratio of 0.07 and diameter of 1.06m, powered by
a hydraulic motor, has been tested at a height of 0.47 rotor
diameter above a solid ground board which has an elliptical
leading edge.
Tests have been run at various low advance ratios
(<0.1) with two collective pitch settings.
A three-element hot wire anemometer probe has
been used to measure the average value of the three
components of velocity simultaneously in the forward half
(advancing side) of the rotor wake and in the main stream
surrounding it.
The rotor wake and the ground vortices have been
visualized by smoke. Surface flow patterns on the ground
board have located the interaction region between the rotor
wake and the oncoming flow on the ground board.
Theoretical estimates of the flowfield based on
Heyson's vortex cylinder model (Ref. 2) are compared with the
experimental results.
Both experimental results and theoretical estimates
show that the ground-induced interference is an upwash and
a decrease in forward velocity. The upwash interference'
opposes the vertical flow through the rotor, and have large
effects on the rotor performance in producing thrust. The
streamwise interference decelerates the mainstream and
becomes more noticeable as the wake boundary is approached.
7
Breton, Simon-Philippe. "Study of the stall delay phenomenon and of wind turbine blade dynamics using numerical approaches and NREL’s wind tunnel tests." Doctoral thesis, Norwegian University of Science and Technology, Department of Civil and Transport Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2275.
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Mesrobian, Chris Eden. "Concept Study of a High-Speed, Vertical Take-Off and Landing Aircraft." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/35574.
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The purpose of the study was to evaluate the merits of the DiscRotor concept that combine the features of a retractable rotor system for vertical take-off and landing (VTOL) with an integral, circular wing for high-speed flight. Tests were conducted to generate basic aerodynamic characteristics of the DiscRotor in hover and in fixed-wing flight. To assess the DiscRotor during hover, small scale tests were conducted on a 3ft diameter rotor without the presence of a fuselage. A â hover rigâ was constructed capable of rotating the model rotor at speeds up to 3,500 RPM to reach tip speeds of 500fps. Thrust and torque generated by the rotating model were measured via a two-component load cell, and time averaged values were obtained for various speeds and pitch angles. It has been shown that the DiscRotor will perform well in hover. Ground Effects in hover were examined by simulating the ground with a movable, solid wall. The thrust was found to increase by 50% compared to the ground-independent case. Pressure distributions were measured on the ground and disc surfaces. Velocity measurements examined the flow field downstream of the rotor by traversing a seven hole velocity probe. A wake behind the rotor was shown to contract due to a low pressure region that develops downstream of the disc.
Wind tunnel experimentation was also performed to examine the fixed wing flight of the DiscRotor. These experiments were performed in the VA Tech 6â X6â Stability Tunnel. A model of the fuselage and a circular wing was fabricated based upon an initial sizing study completed by our partners at Boeing. Forces were directly measured via a six degree of freedom load cell, or balance, for free stream velocities up to 200fps. Reynolds numbers of 2 and 0.5 million have been investigated for multiple angles of attack. Low lift-to-drag ratios were found placing high power requirements for the DiscRotor during fixed-wing flight. By traversing a seven-hole velocity probe, velocities in a 2-D grid perpendicular to the flow were measured on the model. The strengths of shed vortices from the model were calculated. A method to improve fixed-wing performance was considered where two blades were extended from the disc. An increase of 0.17 in the CL was measured due to the interaction between the disc and blades.
This research utilized a wide range of experiments, with the aim of generating basic aerodynamic characteristics of the DiscRotor. A substantial amount of quantitative data was collected that could not be included in this document. Results aided in the initial designs of this aircraft for the purpose of evaluating the merit of the DiscRotor concept.
Master of Science
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de, Laval Jonathan. "Simulation of thermal tests in the climatic wind tunnel CD7 at Scania Master thesis project in fluid mechanics." Thesis, KTH, Mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195726.
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The Swedish truck and bus manufacturer Scania has a number of test facilities to support the R&D department and for verification of vehicle properties. The latest addition is the climatic wind tunnel Chassis Dynamometer 7 (CD7) which can fit trucks and buses for full scale testing and maintain temperatures in the range from -35 to 50 degree Celsius in the flow circuit, furthermore it can generate both rain and snow conditions. This means that vehicles can be tested in a controlled and repeatable manner at many critical driving conditions. However, since CD7 is a new facility there is a need to tune and interpret the results generated in the tunnel and translate them to true, on road conditions. In this project the airflow and temperature distribution in the climatic wind tunnel were studied by means of the CFD solver PowerFLOW based on the Lattice Boltzmann method. As a first step the wind tunnel was simulated empty to check the case set up and to understand the basic flow features in the empty tunnel. In the second step a Scania truck was added to the wind tunnel set up, a truck that also exists as a physical test vehicle at Scania R&D. Thirdly, the same vehicle model was simulated in road like conditions to give a reference for comparison. Lastly, a measurement campaign was performed in the climatic wind tunnel in order to get data for comparison and validation of the simulation results. Simulation results show that CD7 displays an overestimate of wind tunnel airspeed. To match heat exchanger mass flow and recirculation temperatures at 30 km/h it is shown that CD7 should indicate closer to 35 km/h. At this low speed range 5 km/h has a strong effect on recirculation of hot air into the cooling package which translates to 1 C increase of air temperature into the charge-air cooler. It also corresponds to an increase of 2 C of the cooling capacity of the vehicle at 30 km/h. Also the temperature in the front air intake system increases by 3 C which is also a significant change that could affect the tuning of the engine. One degree Celsius is within the measurement accuracy of a thermal test at Scania. The simulations at 85 km/h give a corresponding correction of the tunnel velocity around 10 km/h, which means that it is consistently about 10 % off. The experimental results show conformity with the simulations and also support the claim that CD7 indicates an overestimate of the actual airspeed.
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Schouten, Shane Michael. "Complete CFD analysis of a Velocity XL-5 RG with flight-test verification." Texas A&M University, 2008. http://hdl.handle.net/1969.1/85894.
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The Texas A&M Flight Research Laboratory (FRL) recently received delivery of its
newest aircraft, the Velocity XL-5 RG. The Velocity can fly faster than the other aircraft
owned by the FRL and does not have a propeller in the front of the aircraft to disrupt the
air flow. These are definite advantages that make the Velocity an attractive addition to
the FRL inventory to be used in boundary-layer stability and transition control. Possible
mounting locations built into the aircraft for future projects include hard points in the
wings and roof of the fuselage. One of the drawbacks of the aircraft is that it has a
canard ahead of the main wing that could disrupt the incoming flow for a wing glove or
research requiring test pieces mounted to the hard point in the wing. Therefore, it is
necessary to understand the influence the canard and the impact of its wake on the wing
of the aircraft before any in-depth aerodynamic research could be completed on the
aircraft.
A combination of in-flight measurements of the canard wake and Computational
Fluid Dynamics (CFD) were used to provide a clear picture of the flowfield around the
aircraft. The first step of the project consisted of making a 3-D CAD model of the
aircraft. This model was then used for the CFD simulations in Fluent. 2-D, 3-D, inviscid,
and viscous simulations were preformed on the aircraft. A pressure rake was designed to
house a 5-hole probe and 18 Pitot probes that extended forward of the main wing to
measure the location and strength of the canard wake at various flight conditions. There
were five primary test points that were recorded at multiple times over the course of three flights. Once all of the data were collected from the flights, the freestream
conditions became the inputs into the final, 3-D CFD simulations on the aircraft.
The good agreement between the CFD results and the in-flight measurements
provided the necessary verification of the CFD model of the aircraft. These results can
be used in the future planning and execution of experiments involving the Velocity XL-5
RG.
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Kim, Daeung. "The Application of CFD to Building Analysis and Design: A Combined Approach of an Immersive Case Study and Wind Tunnel Testing." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/25140.
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Computational Fluid Dynamics (CFD) can play an important role in building design. For all aspects and stages of building design, CFD can be used to provide more accurate and rapid predictions of building performance with regard to air flow, pressure, temperature, and similar parameters.
Generally, the process involved in conducting CFD analyses is relatively complex and requires a good understanding of how best to utilize computational numerical methods. Moreover, the level of skill required to perform an accurate CFD analysis remains a challenge for many professionals particularly architects. In addition, the user needs to input a number of different items of information and parameters into the CFD program in order to obtain a successful and credible solution.
This research seeks to improve the general understanding of how CFD can best be used as a design assistance tool. While there have been a number of quantitative studies suggesting CFD may be a useful tool for building related airflow assessment, few researchers have explored the more qualitative aspects of CFD, in particular developing a better understanding of the procedures required for the proper application of CFD to whole building analysis. This study therefore adopted a combined qualitative and quantitative methodology, with the researcher immersing himself into a case study approach and defining several lessons-learned that are documented and shared. This research will assist practicing architects and architecture students to better understand the application of CFD to building analysis and design.Ph. D.
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Gibbs, Jason. "Experimental Determination of Lift and Lift Distributions for Wings In Formation Flight." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/31301.
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Experimental methods for the investigation of trailing vortex strengths, total lift, and lift distributions for three-dimensional wings in close proximity flight were developed. With these experiments we model compound aircraft flight either docked tip-to-tip, or flying in formation. There is a distinct lack of experimental formation flight data using three-dimensional wing models for tests. The absence of fixed walls on either end of the wing permits the development of the asymmetric shedding of vortices, and the determination of the asymmetric circulation distribution induced by the proximity of the leading wing. The pair consisted of a swept NACA-0012 non-cambered wing simulating one half of a leading aircraft and a rectangular cambered NACA 63-420 wing simulating the trailing aircraft. Important aspects of the work included theoretical development, experimental setup, data acquisition and processing, and results validation. Experimentally determining the lift for formation flight, in addition to the local flow behavior for a pair of wings, can provide valuable insight for the proposition of flying actual aircraft in formation to increase mission efficiency. To eliminate the need for bulky mounting stings and direct load measurement devices that can potentially interfere with the local flowfield, a minimally invasive velocity probe method is developed. A series of experiments were performed to assist with the development of the method. Velocity and vorticity distributions obtained along a near-field plane were processed to calculate wingtip vortex strengths. Additionally, vortex position instabilities and the shedding of vorticity inboard of the wingtips were observed. To determine the circulation distributions for the trailing wing, the initial method is modified. By processing velocity information acquired in a near-field plane, both the lift and induced drag were calculated for the trailing airfoil. Comparisons are made to directly measured loads and to results reported earlier. Directly measured lift and drag coefficients were found to agree with existing literature.Master of Science
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Wang, Jiaqi. "Aerodynamic performance of bluff bodies with openings on side surface." Kyoto University, 2020. http://hdl.handle.net/2433/253252.
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Dumon, Jéromine. "Etude expérimentale et numérique du phénomène de tremblement transsonique sur un profil diamant." Thesis, Toulouse, ISAE, 2020. http://www.theses.fr/2020ESAE0009.
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Le développement de lanceurs spatiaux réutilisables nécessite une connaissance appro-fondie des effets des écoulements transsoniques sur la structure du lanceur, commele tremblement transsonique. En effet, l’intégrité mécanique du lanceur peut êtrecompromise par des interactions onde de choc/couche limite. Ces interactions peuventinduire, par exemple, des forces latérales responsables des moments de roulis et detangage, ou une excitation modale de certains éléments de structure pouvant conduireà leur endommagement, voire leur rupture. Ce travail rapporte des études numériqueset expérimentales sur la caractérisation de l’écoulement transsonique autour d’un aileronà profil losangique, conçu pour les lanceurs dédiés aux nanosatellites, avec un intérêtparticulier pour le tremblement transsonique. Ce phénomène a été longuement étudié.Malheureusement, les mécanismes intimes à l’origine du tremblement et la dynamiquedu phénomène sont encore débattus. De plus, il y a un manque d’études sur lesprofils losangiques. Des visualisations strioscopiques résolues en temps, des mesuresde pressions stationnaire et instationnaire pariétales ainsi que des mesures LDV sontréalisées expérimentalement dans une soufflerie transsonique. Les résultats sont comparésà des prédictions numériques basées sur des approches RANS instationnaire et LES. Lestraits tridimensionnels du tremblement transsonique et son caractère chaotique sur unprofil diamant sans flèche sont mis en évidence expérimentalementThe development of reusable space launchers requires a comprehensive knowledge oftransonic flow effects on the launcher structure, such as buffet. Indeed, the mechanicalintegrity of the launcher can be compromised by shock wave/boundary layer interactions.These interactions can induce, amongst others, lateral forces responsible for rolling andpitching moments, or modal excitation of some structural elements that can lead to theirdamage or even failure. This work reports numerical and experimental investigationson the characterization of the transonic flow past a diamond airfoil, designed fornanosatellite-dedicated launchers, with a particular interest for buffeting. Buffeting hasbeen extensively studied. Unfortunately, the detailed mechanisms that are responsiblefor the buffet inception and its dynamics are still debated. Moreover, there is a lackof studies for diamond airfoils. Here, time-resolved Schlieren visualizations, steadyand unsteady pressure measures and LVD measures are experimentally conducted ina transonic wind tunnel. They are compared with numerical predictions based on un-steady RANS and LES approaches. Three dimensional features of buffet over a diamondairfoil without swept, and the occurrence of a chaotic state, are experimentally highlighted
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BRUSCO, STEFANO. "Transient phenomena induced by thunderstorm outflows on slender structures." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1051022.
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The climatology at mid-latitudes (for instance, Europe) is dominated by both extra-tropical depressions at the synoptic scale and by mesoscale thunderstorm outflows (also called downbursts). Thunderstorm outflows are non-stationary phenomena, complex and potentially devastating, which strongly differ from synoptic winds under many points of view (genesis, scale, duration above all). Consequently, the induced wind fields are highly different. Modern codes and guidelines are mainly based on the cyclonic model, because of the persistent lack of knowledge about thunderstorm outflows, in particular concerning full-scale measurements. On the other hand, severe wind damage is often induced by downbursts, especially concerning low- and medium- rise structures (e.g., cranes, small turbines, light poles, low-canopies).
The present PhD Thesis is collocated within the framework of the ERC THUNDERR Project. It investigates aspects connected with the aerodynamic loading of structures subjected to thunderstorm outflows, particularly focusing on the transient aerodynamics and transient aeroelasticity. This is firstly pursued through the definition of analytical formulations which, starting from compatible vertical wind fields, permit to evaluate the aerodynamic wind loading by using the strip and quasi-steady theory. The application of the procedures on selected slender test structures shows that a crucial role is played by thunderstorm-induced variations of the wind angle of attack, which may increase or reduce the structure response. The second part of the Thesis is devoted to an extensive experimental campaign carried out at the multiple-fan wind tunnel of the Tamkang University, Taipei, which is able to simulate unsteady flows. The sectional model of a sharp-edged square cylinder, equipped with 94 pressure taps, is investigated and numerous configurations of the flow parameters are considered in order to study the effects of acceleration on the aerodynamic loads and on the vortex-shedding from the body. The drag coefficients and the fluctuating cross-flow force coefficients connected with vortex shedding are found to be either comparable or definitely lower than their corresponding values for steady flows. Furthermore, discontinuities of the shedding frequency are present during the transients and their number and magnitude appear to be connected with the acceleration of the flow.
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Bueno, Ana Paula Franco. "Análise experimental das medidas de pressão em regime não-estacionário em um perfil de aerofólio NACA0012." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18148/tde-03022016-092628/.
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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.
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Westin, Michelle Fernandino. "Aeroelastic modeling and experimental analysis of a flexible wing for wind tunnel flutter test." Instituto Tecnológico de Aeronáutica, 2010. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1121.
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The objective of this work is to investigate the flutter phenomena experimentally, which will unify high aspect ratio wings design for wind tunnel flutter tests (Dowell and Tang, 2002), cheaper aeroelastic models construction and a procedure used by Sheta, Harrand, Thompson and Strganac (2002) to identify the flutter onset power spectral density versus the frequency. Initially, an experimental model developed by Dowell and Tang (2002) has been considered as a baseline model and, from this point, two new models with different wing configurations were determined, including the slender body at wing's tip, which is the idea extracted from Dowell's work, so that the torsion and bending modes are coupled (torsional moment of inertia reduction). The aeroelastic model can be divided into two parts: First, the wings structural dynamic models are computed using the finite element method implements in NASTRAN solver. sequently, ZAERO software is employed to compute the aeroelastic model. Unsteady aerodynamic loading is computed through a lifting surface interference method known as ZONA 6. The wing models defined as test beds will be constructed and tested in different wind tunnels, including open and closed tests section types. The power spectral density approach might be employed as a way to identify flutter. The output signal from an accelerometer placed in the wing structure allows, through its power spectral density computation, the identification of flutter onset condition and the corresponding undisturbed flow speed. The PSD function increase means flow energy extraction, a condition to have flutter. Experimental flutter speeds are close to the theoretically computed ones by ZAERO. From these observations, it is possible to validate the aeroelastic theoretical model in a small disturbance context. After flutter onset , the limit cycle oscillations are observed, fed by freestream energy extraction. The aeroelastic models under investigation in this research are excellent models for nonlinear aeroelastic phenomena behavior study.
18
Dwyer, William P. (William Patrick). "Measurement of flow boundary condition data and wing pressures in a wind tunnel test of a 45 deg swept wing." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/42182.
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Zientarski, Lauren Ann. "Wind Tunnel Testing of a Variable Camber Compliant Wing with a Unique Dual Load Cell Test Fixture." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1448893315.
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Hamilton, Christianne Rhea. "Design of Test Sections for a High Enthalpy Wind Tunnel." MSSTATE, 2003. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04082003-114126/.
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This document describes the design of a supersonic and a subsonic test section for a high enthalpy wind tunnel. A streamline is tracked through a supersonic test section using the method of characteristics. The specifics of the design program and the design techniques are illustrated for the supersonic section. The section of the paper dealing with the subsonic nozzle has a greatly diverse nature. This section details the inlet and exhaust restrictions and construction elements for the entire low speed system. The system is currently being set up for testing with the subsonic section, and the supersonic will eventually follow.
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Lines, Philipp A. "Upgrade of a LabVIEW based data acquisition system for wind tunnel test of a 1/10 scale OH-6A helicopter fuselage." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FLines.pdf.
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Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, June 2003.Thesis advisor(s): E. Roberts Wood, Richard M. Howard. Includes bibliographical references (p. 53-54). Also available online.
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Sparks, Russell. "A novel six degree of freedom dynamic wind tunnel test facility." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492066.
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Tourn, Cremona Silvana Cecilia. "Characterization of a New Open Jet Wind Tunnel to Optimize and Test Vertical Axis Wind Turbines." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/461079.
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Basat en el creixent interès en les tecnologies ambientals urbanes, l'estudi de turinas d'eix vertical de petita escala mostra desafiaments motivadors. En aquesta tesi, es presenten els criteris de disseny, les característiques i potencialitats d'un nou túnel de vent de secció de prova oberta. Té un àrea de sortida i la broquet del túnel de 1,5 x 1,5 m2, i es pot operar amb velocitats de sortida de 3 m / s a 17 m / s. La caracterització del flux s'ha dut a terme amb tubs pitot calibrats, anemòmetres de cassoletes i anemòmetres de fil calent. Es consideren dues configuracions diferents de l'àrea de prova, amb i sense sostre. Els mesuraments en el rang de velocitats de sortida disponibles mostren que la secció transversal, on les intensitats de velocitat i turbulència mostren un nivell acceptable d'uniformitat, té una àrea de 0,8 x 0,8 m2 i una dimensió de 2 m des de la sortida del broquet del túnel. En aquesta secció de treball, la intensitat màxima de la turbulència és del 4%. La caracterització detallada del flux realitzat indica que el túnel de vent es pot utilitzar per provar models a d'aerogeneradors de petita escala.Basado en el creciente interés en las tecnologías ambientales urbanas, el estudio de turinas de eje vertical de pequeña escala muestra desafíos motivadores. En esta tesis, se presentan los criterios de diseño, las características y potencialidades de un nuevo túnel de viento de seccion de prueba abierta. Tiene un área de salida e la boquilla del túnel de 1,5 x 1,5 m2, y se puede operar con velocidades de salida de 3 m/s a 17 m/s. La caracterización del flujo se ha llevado a cabo con tubos pitot calibrados, anemómetros de cazoletas y anemómetros de hilo caliente. Se consideran dos configuraciones diferentes del área de prueba, con y sin techo. Las mediciones en el rango de velocidades de salida disponibles muestran que la sección transversal, donde las intensidades de velocidad y turbulencia muestran un nivel aceptable de uniformidad, tiene un área de 0,8 x 0,8 m2 y una dimensión de 2 m desde la salida de la boquilla del túnel. En esta sección de trabajo, la intensidad máxima de la turbulencia es del 4%. La caracterización detallada del flujo realizado indica que el túnel de viento se puede utilizar para probar modelos a de aerogeneradores de pequeña escala.
Based on the increasing interest in urban environmental technologies, the study of small scale vertical axis wind turbines shows motivating challenges. In this thesis, we present the design criteria, characteristics and potentials of a new open jet wind tunnel. It has a nozzle exit area of 1.5 x1.5 m2, and it can be operated with exit velocities from 3 m/s to 17 m/s. The characterization of the flow has been carried out with calibrated pitot tubes, cup anemometers, and hot wire anemometers. Two different configurations of the test area, with and without a ceiling, are considered. Measurements in the range of available exit velocities show that the cross section, where the velocity and turbulence intensities show an acceptable level of uniformity, has an area of 0.8 x 0.8 m2 and a streamwise dimension of 2 m from the nozzle exit of the tunnel. In this working section, the maximum turbulence intensity is 4%. The detailed characterization of the flow carried out indicates that the wind tunnel can be used to test small scale models of wind turbines.
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Acevedo, Giraldo Daniel. "Experimental and analytical investigation of the aerodynamic noise emitted by generic distributed electric propulsion wing-propellers configurations." Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2024. http://www.theses.fr/2024ECDL0015.
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Cette thèse étudie expérimentalement et analytiquement les effets d'installation acoustiques d'une paire d’hélices subsoniques de six pales installées côte à côte et près du bord de fuite d’une aile. Dans une gamme importante de basses et moyennes fréquences, le diamètre des hélices, la corde de l'aile et la distance aile-hélice sont plus petites que les longueurs d'onde acoustiques, atteignant un régime compact. Cette configuration générique imite les futures architectures d'avions urbains à propulsion électrique distribuée, adressée dans le cadre du projet H2020 de l’Union européenne ENODISE. Les effets d'installation se référent aux sources supplémentaires de bruit aérodynamique provoquées par l'interaction pale-aile et à leur diffraction par l'aile, par rapport au cas d'hélices isolées. Ce travail vise à trouver une configuration générique optimale aérodynamique et acoustique à travers une étude paramétrique. L'idée est de démontrer la capacité de l'approche expérimentale à déterminer les configurations optimisées et le potentiel des modèles analytiques pour estimer l’effet de diffraction du son, qui présente un intérêt primordial pour les étapes préliminaires de conception d'un système. Des essais en soufflerie sont d’abord effectués à titre de référence, puis un modèle analytique est implémenté et ses prédictions sont validées avec les résultats expérimentaux. Enfin, cela permettra de trouver des options intéressantes pour l’intégration propulsion-cellule. Des essais en soufflerie ont été réalisés dans l'installation à jet ouvert anéchoïque de l'École Centrale de Lyon. Les mesures aérodynamiques ont été faites par des prises de pression statique sur l'aile, alors que les performances aéropropulsives ont été évaluées à l'aide de cellules de pesée. De plus, le bruit en champ lointain était mesuré avec une antenne de microphones rotative, explorant une partie d’une sphère autour de l’installation. Les hélices ont été testées à une vitesse de rotation constante de 7000 tr/min dans des conditions statiques. L'amplitude et la directivité de la pression acoustique aux fréquences de passage des pales ont été explorées de manière exhaustive pour les différents cas. Le contenu spectral de cas sélectionnés a été examiné plus en détail, montrant les impacts de la régénération de son par diffraction ou du masquage en fonction de la position des hélices. Les résultats montrent des positions pour lesquelles il existe un potentiel important d'atténuation du bruit. Des réductions allant jusqu'à 5 dB du niveau de pression acoustique global et 20 dB à la fréquence de passage des pales ont été observées. De plus, les données montrent que l'effet d'installation est crucial pour analyser le bruit tonal des hélices. En particulier, le rayonnement sonore est considérablement augmenté lorsque les extrémités des pales fonctionnent à proximité du bord de fuite de l'aile. De plus, dans le cadre de la formulation analytique, les sources de bruit de type dipolaire des hélices sont prises en compte, en supposant des pales rigides. Le rayonnement sonore des hélices est formulé en trois dimensions, en s'appuyant sur la notion de modes-sources pour représenter le bruit tonal. Par ailleurs, la fonction de Green du demi-plan a permis de prendre en compte la diffraction du son par l'aile. Une correction de corde finie a été appliquée et validée par simulations numériques. Les résultats ont confirmé que l'effet d'installation est crucial pour analyser le bruit tonal. Les calculs ont été comparés favorablement aux mesures du bruit en soufflerie en champ lointain. Les résultats montrent qu'en présence d'une aile, des composantes du bruit évanescentes en champ libre peuvent être converties en modes de rayonnement très efficaces si les sources sont à une distance compacte du bord de fuite de l'aile. Ceci redonne de l'importance au bruit de charge stationnaire, le plus souvent d'importance secondaire en champ libre par rapport au bruit de charge instationnaireThe present thesis investigates experimentally and analytically the acoustic installation effects of a pair of six-bladed side-by-side subsonic propellers installed near a wing's trailing edge. In a significant range of low-and-middle frequencies, the propellers' diameter, wing chord, and propeller-wing distance are smaller than the acoustic wavelengths, reaching a compact regime. This generic configuration mimics future Distributed Electric Propulsion urban aircraft architectures, addressed in the framework of the European Union's H2020 project ENODISE. The installation effects refer to the additional sources of aerodynamic noise caused by blade-wing interaction and their scattering by the wing, compared to the case of isolated propellers. This work aims to find an optimum generic configuration concerning aerodynamic and acoustic standpoints through a parametric study. The idea is to demonstrate not only the ability of the experimental approach to determine optimized configurations but also the potential of analytical models to estimate this sound-scattering effect, which is of primary interest for the preliminary design steps of a system. Firstly, wind tunnel tests are performed as a reference. Secondly, an analytical model is implemented and its predictions are validated with the experimental results. Finally, this will help to find interesting options for propulsion-airframe integration. Wind tunnel tests have been conducted in the anechoic open-jet facility at École Centrale de Lyon. Aerodynamic measurements were taken by static pressure taps on the wing, whereas the aero-propulsive performance was evaluated with load cells. In addition, the far-field sound was measured with a rotating microphone antenna, exploring part of a sphere around the setup. The propellers were tested at a constant rate of 7000 rpm in static conditions. Variations in magnitude and directivity of the sound pressure levels at the first blade passing frequency tones were explored comprehensively for the different cases. The spectral content of selected cases of interest was examined in greater detail, showing the impacts of acoustic scattering, diffraction, reflection, and shielding depending on the propeller position. The results show positions at which there is significant potential for noise attenuation by masking both the tonal and broadband noise content. Reductions of up to 5~dB in the overall sound pressure level and 20 dB in the first blade passing frequency were evidenced. Additionally, the data show that the installation effect is crucial for analyzing tonal propeller noise. In particular, sound radiation is significantly increased when the blade tips operate close to the trailing edge. Furthermore, in the analytical formulation, dipole-like noise sources of the propellers are considered, assuming rigid blades. The sound radiation from the propellers is formulated in three dimensions for characteristic spinning modes of tonal noise. In addition, the half-plane Green's function is used to account for the sound scattering by the wing. A finite-chord correction is applied, and validated by numerical simulations. The results confirmed that the installation effect is crucial for analyzing tonal propeller noise. This approach was quantitatively assessed against the far-field wind tunnel sound measurement. Sound pressure maps show that in the presence of the wing, radiation modes that would be evanescent in free-field can be converted into very effectively radiating patterns if the blade tips of the installed propellers are at a compact distance from the wing trailing edge. This effect tends to increase the radiation efficiency of steady-loading noise, which is most often of secondary importance compared to unsteady-loading noise in free field
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Capasso, Michael Anthony. "Construction and wind tunnel test of a 1/12th scale helicopter model." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA288487.
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Hamm, Christopher Eric. "AN ASSESSMENT OF FLOW QUALITY IN AN OPEN TEST SECTION WIND TUNNEL." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11022009-115210/.
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The subsonic wind tunnel facility at Mississippi State University has been converted to an open test section configuration. An experimental setup was developed which is easily configurable to allow for further research. Measurements of flow quality over select portions of the test section were made to attain a basic understanding of the performance of the new configuration. A program was developed in LabVIEW to control a 3-axis traverse and perform necessary data reduction. The traverse control program was developed to perform data acquisition using a hot-film probe to facilitate the necessary measurements. Data was gathered at two wind tunnel velocity settings over several test section locations. Results of the testing program yielded recommendations on the use of the open configuration. This paper documents the procedure and setup of the testing program to include discussion of the control/data acquisition program and a discussion of the findings and recommendations.
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Dalley, Sam. "Wind tunnel measurements on a low rise building and comparison with full-scale." Thesis, University of Surrey, 1993. http://epubs.surrey.ac.uk/886/.
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Ying, Pei. "Aerodynamic analysis of a novel wind turbine for an omni-flow wind energy system." Thesis, University of Hertfordshire, 2016. http://hdl.handle.net/2299/17355.
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The purpose of this research is to propose a novel wind turbine for an omni-flow wind energy system and investigate its aerodynamic performance. The geometry of the novel wind turbine is based upon the impulse turbine technology which has been successful in wave energy. In this study, both numerical and experimental studies were conducted to evaluate the aerodynamic features of this wind turbine. The numerical method was validated by a comparison between numerical and experimental results over a range of tip speed ratios. Results obtained from experiments and simulations indicate that the proposed wind turbine can be employed. Additionally, on the basis of the analyses performed, this new wind turbine has the potential for having a good startup feature, which means that this wind turbine can be suitable for applications in an urban environment. As an important component, the stator of this wind turbine can increase the passing flow velocity by 20%. Meanwhile, the passing flow direction also can be optimised by the stator. Aerodynamics of the wind turbine was analysed under the non-uniform flow condition, because the flow is non-uniform inside the omni-flow wind energy system. It was found that the maximum power coefficient of such a turbine under the non-uniform flow condition is lower than that under the uniform flow condition. Due to the non-uniform flow, the blades experience different flow velocities, and as a consequence, undergo different aerodynamic loads during one operation cycle. Thus the generated torque and thrust on a blade are subjected to frequent and periodical changes. Influences of the geometrical parameters on the aerodynamic characteristics of this wind turbine were investigated. From the initial study, it was found that changes of hub-to-tip ratios, numbers of blades, aerofoils and numbers of guide vanes, can significantly affect the II power performance. Additionally, the wind turbine obtained high values of maximum torque coefficients with changing geometrical parameters.
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Bin, Ab Wahab Abas. "The development of computer package for determining and solving pedestrian wind environmental discomfort and its wind tunnel validity test." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305099.
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Broughton, Cabot A. Carleton University Dissertation Engineering Aeronautical. "Experimental investigation of slotted wall wind tunnel test sections for low interference road vehicle testing." Ottawa, 1990.
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Taylor, Nigel John. "Adaptive wall technology for two-dimensional wind tunnel testing at high subsonic through to low supersonic speeds." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294622.
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Clark, Kylen D. "A Numerical Comparison of Symmetric and Asymmetric Supersonic Wind Tunnels." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447071393.
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Sidelko, Stephanie. "Benchmark of aerodynamic cycling helmets using a refined wind tunnel test protocol for helmet drag research." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40486.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 30).
The study of aerodynamics is very important in the world of cycling. Wind tunnel research is conducted on most of the equipment that is used by a rider and is a critical factor in the advancement of the sport. However, to date, a comprehensive study of time-trial helmets has not been performed. This thesis presents aerodynamic data for the most commonly used time-trial helmets in professional cycling. The helmets were tested at a sweep of yaw angles, from 0⁰ to 15⁰, in increments of 5⁰. The helmets were tested at three head angle positions at each yaw angle in order to best mimic actual riding conditions. A control road helmet was used to serve as a comparative tool. In order to maintain manufacturer confidentiality, the helmets were all randomly assigned variables. Thus, the thesis presents ranges of benefit and drag numbers, but does not rank by helmet name. The testing results showed that aerodynamic helmets offer drag reduction over a standard road helmet. The best and the worst performing helmets are all more aerodynamic than a road helmet.
by Stephanie Sidelko.
S.B.
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Ehrmann, Robert S. "Development of Measurement Methods for Application to a Wind Tunnel Test of an Advanced Transport Model." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/369.
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California Polytechnic State University, San Luis Obispo is currently working towards developing a Computational Fluid Dynamics (CFD) database for future code validation efforts. Cal Poly will complete a wind tunnel test on the Advanced Model for Extreme Lift and Improved Aeroacoustics (AMELIA) in the National Full-Scale Aerodynamics Complex (NFAC) 40 foot by 80 foot wind tunnel at NASA Ames Research Center in the summer of 2011. The development of two measurement techniques is discussed in this work, both with the objective of making measurements on AMELIA for CFD validation.
First, the work on the application of the Fringe-Imaging Skin Friction (FISF) technique to AMELIA is discussed. The FISF technique measures the skin friction magnitude and direction by applying oil droplets on a surface, exposing them to flow, measuring their thickness, and correlating their thickness to the local skin friction. The technique has the unique ability to obtain global skin friction measurements. A two foot, nickel plated, blended wing section test article has been manufactured specifically for FISF. The model is illuminated with mercury vapor lamps and imaged with a Canon 50D with a 546 nm bandpass filter. Various tests are applied to the wing in order to further characterize uncertainties related with the FISF technique. Human repeatability has uncertainties of ±2.3% of fringe spacing and ±2.0° in skin friction vector direction, while image post processing yields ±25% variation in skin friction coefficient. A method for measuring photogrammetry uncertainty is developed. The effect of filter variation and test repeatability was found to be negligible. A validation against a Preston tube was found to have 1.8% accuracy.
Second, the validation of a micro flow measurement device is investigated. Anemometers have always had limited capability in making near wall measurements, driving the design of new devices capable of measurements with increased wall proximity. Utilizing a thermocouple boundary layer rake, wall measurements within 0.0025 inches of the surface have been made. A Cross Correlation Rake (CCR) has the advantage of not requiring calibration but obtaining the same proximity and resolution as the thermocouple boundary layer rake. The flow device utilizes time of flight measurements computed via cross correlation to calculate wall velocity profiles. The CCR was designed to be applied to AMELIA to measure flow velocities above a flap in a transonic flow regime. The validation of the CCR was unsuccessful. Due to the fragile construction of the CCR, only one data point at 0.10589 inches from the surface was available for validation. The subsonic wind tunnel’s variable frequency drive generated noise which could not be filtered or shielded, requiring the use of a flow bench for validation testing. Since velocity measurements could not be made in the flow bench, a comparison of a fast and slow velocity was made. The CCR was not able to detect the difference between the two flow velocities. Currently, the CCR cannot be applied on AMELIA due to the unsuccessfully validation of the device.
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Szleper, Michele Lee. "Converging nozzle design for a subsonic wind tunnel to test heat sinks under impinging and parallel airflows." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17124.
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Barbosa, Átila Antunes França. "Influência da asa em gaivota nos coeficientes aerodinâmicos de uma aeronave." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18148/tde-15112015-170422/.
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Desde o início da década de 2010, o aumento do preço do combustível de aviação e a pressão da sociedade para redução da emissão de gases nocivos ao meio ambiente, junto com a necessidade de redução de ruído durante as fases de decolagem e pouso, levaram as companhias aéreas a buscar aeronaves mais eficientes. Para suprir essa demanda, os fabricantes de aviões comerciais solucionaram esse problema através do uso de motores de maior desempenho, que apresentam maior diâmetro que motores de gerações passadas. Desse modo, foi necessário projetar asas com maior diedro na região da raiz, possibilitando a instalação desses novos motores, e diedro menor após a seção do motor, adotando assim a solução de asa em gaivota. O presente trabalho visa analisar o impacto de diferentes tipos de asas em gaivota nos coeficientes aerodinâmicos de uma aeronave de configuração comercial típica. Para tanto, foi realizada uma revisão bibliográfica dos estudos envolvendo asas em gaivota. Numa primeira fase foi feito um estudo analítico das características aerodinâmicas de alguns modelos de aeronaves com asa em gaivota, e em uma segunda fase, foram empregadas ferramentas computacionais para analisar seus comportamentos aerodinâmicos. Posteriormente, em uma terceira fase, esses modelos foram ensaiados no túnel de vento do LAE (Laboratório de Aerodinâmica da EESC/USP), e os resultados das três fases foram comparados.Since the beginning of the 2010s, the increasing price of aviation fuel and the pressure of society to reduce the emission of harmful gases into the environment, coupled with the need of noise reduction during the takeoff and landing, induce carrier companies to look for more efficient airplanes. To furnish this demand, the airplane manufacturers solved the problem using high performance engines, which present a larger diameter than the engines from previous generations. Thereby, it was necessary to project wing with higher dihedral on the root portion, enabling the installation of these new engines, and a lower dihedral after the engine section, thus adopting a gull wing solution. This research project aims at analyzing the impact of different types of gull wing on the aerodynamic coefficients of a typical commercial configuration airplane. For this purpose, a bibliographic review about the studies related to gull wings was performed. In a first phase, an analytical analysis of the aerodynamic characteristics of some airplane model with gull wings was done, and in a second phase, computational programs was used to study their aerodynamic behavior. Later, in a third phase, these models were tested in the wind tunnel of LAE (Laboratory of Aerodynamics of EESC/USP), and the results from the three phases were compared.
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Unal, Sadullah Utku. "Design, Construction And Preliminary Testin Of An Aeroservoelastic Test Apparatus To Be Used In Ankara Wind Tunnel." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607034/index.pdf.
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In this thesis, an aeroservoelastic test appratus is designed to investigate the flutter phenomena in a low speed wind tunnel environment. Flutter is an aeroelastic instability that may occur at control surfaces of aircrafts and missiles. Aerodynamic, elastic, and inertial forces are involved in flutter. A mathematical model using aeroelastic equations of motion is derived to investigate flutter and is used as a basis to design the test setup. Simulations using this mathematical model are performed and critical flutter velocities and frequencies are found. Stiffness characteristics of the test setup are determined using the results of these simulations. The test setup is a two degrees of freedom system, with motions in pitch and plunge, and is controlled by a servomotor in the pitch degree of freedom. A NACA 0012 airfoil is used as a control surface in the test setup. Using this setup, the flutter phenomena is generated in Ankara Wind Tunnel (AWT) and experiments are conducted to validate the results of the theoretical aeroelastic mathematical model calculations.
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Yu, Kevin Xin Jun. "Investigation of Recessed and Concealed Sprinklers Activation in Wind Tunnel Plunge Test and in BRANZFIRE Computer Model." Thesis, University of Canterbury. Civil Engineering, 2007. http://hdl.handle.net/10092/1184.
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Installation of exposed fire sprinklers may cause inconvenience in areas where architectural and interior presentation is significant. In order to overcome this inconvenience, recessed and concealed sprinklers were created and are applied widely. Response Time Index (RTI) and C-factor are the thermal sensitivity (intrinsic parameters) used to characterise a sprinkler. They are also used as input parameters in computer fire models to simulate sprinkler response time. However, the RTI and C-factor are not published by the manufactures. Therefore the RTI and C-factor of the recessed and concealed sprinklers have been analysed and determined in this research. In order to obtain the RTI of the recessed and concealed sprinklers, four of the most commonly used sprinkler models (two recessed and two concealed) in New Zealand have been investigated in plunge test experiment by using a wind tunnel in this research. The UC3 wind tunnel used to conduct the plunge test has been fabricated in this research. This work has demonstrated that the UC3 wind tunnel could provide a very stable and uniform temperature profile in the test section. However, the velocity uniformity of the tunnel needs to be improved in the future. The "apparent" RTI for different recessed and concealed sprinkler models (two recessed and two concealed) have been determined in the plunge test experiment. It should be noted that the "final calculated RTI" for each tested recessed and concealed sprinklers has been denoted as "apparent RTI" in this study. BRANZFIRE computer model has been used to model the fire scenarios in the full scale fire tests conducted by Bill and Heskestad (1995). The best input fire object location, the best input sprinkler distance below the ceiling and the input "apparent C-factor" in BRANZFIRE for the flush, recessed, concealed and the recessed sidewall sprinklers have been determined in this research. This work has generally improved the guidance available to fire safety engineers for the RTI and C-factor of the recessed and concealed sprinklers.
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Gobbi, Giangiacomo. "Analysis and reconstruction of dynamic-stall data from nominally two-dimensional aerofoil tests in two different wind tunnels." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/1362/.
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This work is a specific investigation into low speed aerofoils. The term “low speed” is normally used to indicate free stream velocity less than Mach = 0.5 and, here, not more than 0.2 M when considering dynamic-stall. This field of investigation, for the QinetiQ aerofoil, has been somewhat ignored till now to the advantage of higher speeds starting from 0.3 M. In order to improve the knowledge of the behaviour of aerofoils under M<0.2 conditions, the University of Glasgow, in cooperation with QinetiQ, carried out two-dimensional aerodynamic tests on a RAE9645 aerofoil in 2002. By the end of November, of the same year, high quality unsteady pressure measurements from dynamic-stall tests were available. The tests were conducted on two different RAE9645 aerofoil models in two different wind tunnels. The first of these data came from the aerofoil that was tested in the Department of Aerospace’s Handley Page Wind Tunnel. The second data set was from tests carried out by QinetiQ on an aerofoil in the Department of Aerospace’s Argyll Wind Tunnel. The objectives of this investigation are divided in three main topics. First part considers the analysis of the data. This means (a) the assessment of the aerodynamic coefficients and consequent analysis of the various features of the dynamic-stall including the critical angle, the pitching moment and stall onset. (b) A comparison of the overall aerodynamic coefficients and (c) the carry out of final analysis of the most important quantities such as Cp deviation, vortex development and convection speed and re-establishment of fully attached flow. The assessment of the all same quantities for the second aerofoil tested by QinetiQ and the comparison of them xxiii with the first model are the objectives of the second part of the project. Hence a most useful comparison of two data sets from two different wind tunnels will be achieved. The third part was to establish the coefficients for the Beddoes third generation dynamic-stall model for the clean aerofoil without any flow control, using both aerofoil data. The Beddoes third generation dynamic-stall model is the last version of a model which has been in constant development over thirty years and is known as the most popular semi empirical method for assessing unsteady airloads such as lift, drag and pitching moment. This applies both to helicopters and wind turbines. The simplicity and undergoing philosophy of this method is its strength, especially compared with the current solution of Navier-Stokes or Euler equations. At the completion of this work, all the coefficients and information necessary for running the Beddoes simulating dynamicstall model were obtained for the RAE9645 aerofoil. At the same time refinements, improvements and new guide lines were pursued in order to make the model easier and more powerful than before. Some of these changes are associated only to low Mach numbers. It has been concluded that the Beddoes’ model has been enhanced to better re-construct the RAE9645 aerofoils data of low Mach numbers.
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Chen, Ru-Ching. "Development of a Supersonic Nozzle and Test Section for use with a Magnetic Suspension System for Re-Entry Aeroshell Models." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1544179612537658.
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Brown, Kenneth Alexander. "A Study of Aerodynamics in Kevlar-Wall Test Sections." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49383.
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This study is undertaken to characterize the aerodynamic behavior of Kevlar-wall test sections and specifically those containing two-dimensional, lifting models. The performance of the Kevlar-wall test section can be evaluated against the standard of the hard-wall test section, which in the case of the Stability Wind Tunnel (SWT) at Virginia Tech can be alternately installed or replaced by the Kevlar-wall test section. As a first step towards the evaluation of the Kevlar-wall test section aerodynamics, a validation of the hard-wall test section at the SWT is performed, in part by comparing data from NACA 0012 airfoil sections tested at the SWT with those tested at several other reliable facilities. The hard-wall test section showing good merit, back-to-back tests with three different airfoils are carried out in the SWT's hard-wall and Kevlar-wall test sections. Kevlar-wall data is corrected for wall interference with a panel method simulation that simulates the unique boundary conditions of Kevlar-wall test sections including the Kevlar porosity, wall deflection, and presence of the anechoic chambers on either side of the walls. Novel measurements of the boundary conditions are made during the Kevlar-wall tests to validate the panel method simulation. Finally, sensitivity studies on the input parameters of the panel method simulation are conducted. The work included in this study encompasses a wide range of issues related to Kevlar-wall as well as hard-wall tunnels and brings to light many details of the performance of such test sections.Master of Science
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Scharnberg, Fábio Augusto. "Caracterização aerodinâmcia de edifícios através do espectro das cargas totais medidas em túnel de vento." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/181819.
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Nos últimos anos cresceu o interesse por construir edifícios cada vez mais altos, os quais estampam o poderio tecnológico e econômico das nações. Concomitantemente as estruturas se tornaram mais esbeltas e flexíveis e os fenômenos dinâmicos oriundos da ação do vento, que em edificações baixas não representam grande relevância no carregamento, começam a surgir e apresentar seus efeitos. Desta maneira, é importante conhecer como se desenvolve o escoamento do ar e a distribuição das pressões no entorno destas estruturas. Neste trabalho, caracteriza-se aerodinamicamente, através de dados oriundos de ensaios em túnel de vento, dois empreendimentos reais e presentes na engenharia nacional. Os carregamentos foram gerados através da integração simultânea de pressões e transformados em espectros de força, os quais auxiliam na visualização da energia cinética contida nas rajadas, na ocorrência de desprendimento cadenciado de vórtices, martelamento e na influência que as edificações vizinhas apresentam no escoamento. A análise é realizada local e globalmente, possibilitando verificar em que “zona”, ou faixa de altura, é mais significante para o carregamento da estrutura como um todo. O fenômeno de desprendimento de vórtices é caracterizado por um pico no espectro transversal à incidência do vento. Quando existem edificações ou obstáculos na região a barlavento, a estrutura pode ser martelada até a altura média destes obstáculos. Por fim, os resultados aqui apresentados podem servir de auxílio no pré-dimensionamento de estruturas com configurações similares, como comparativo e validação para pesquisas futuras e como referencial na elaboração de códigos normativos referentes ao tema. Destaca-se a importância de ensaios em túnel de vento, principalmente quando a estrutura a ser analisada possui um detalhamento arquitetônico complexo. Estes ensaios permitem ao projetista simular todos os casos de carregamento e os efeitos de vizinhança com maior confiabilidade e precisão em relação a métodos simplificados contidos, atualmente, em códigos e normas.In recent years many high-rise buildings have been built, which are a way to represent the economic and technological power of nations. Concomitantly, the structures have become slender and more flexible, and the dynamic phenomena of wind, which in low buildings do not represent a great relevance in the loading, start to show their effects. In this way, it is extremely important to know how the wind flow and the pressure distribution occur around these structures. In this research, two real projects, present in the national engineering, are characterized aerodynamically through data from wind tunnel tests. The loadings were processed through the simultaneous integration of pressures and transformed into force spectra, which aid in the visualization of the kinetic energy contained in the bursts, in the occurrence of vortex shedding, buffeting and the influence of the neighboring buildings on the wind flow. The analysis is performed locally and globally, making it possible to verify which "zone", or height range, is more significant to the loading of the structure as a whole. It can be seen that the phenomenon of vortex shedding is characterized by a peak in the crosswind spectrum and the buffeting phenomenon appears when there are buildings or obstacles in the windward region. Finally, the results presented here can be helpful in the pre-design of structures with similar configurations, in the comparison and validation for future researches and as a reference in the review of normative codes. Emphasis is given to the importance of wind tunnel testing, which allows the designer to simulate all loading cases and neighborhood effects with greater precision compared to simplified methods currently contained in codes and standards.
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Fisher, David T. "Wind tunnel performance comparative test results of a circular cylinder and 50% ellipse tailboom for circulation control antitorque applications." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283335.
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Minair, Catherine. "Les angles privilégiés, grands invariants universaux : une approche par la dynamique des fluides, l'esthétique et la physio-biologie." Valenciennes, 1987. https://ged.uphf.fr/nuxeo/site/esupversions/a2fee09c-75f7-461c-88c5-71e89bf41c12.
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Des visualisations en soufflerie jusqu'à l'éclatement ont mis en évidence des relations de filiation entre les valeurs toujours privilégiées du système inter tourbillonnaire sur des ailes delta minces et les divers paramètres en particulier l'angle d'apex. L'universalité de la notion d'angle privilégié est soulignée par des considérations architecturales telles que le nombre d'or, et picturales en même temps que par des phénomènes biologiques confirmés par la géométrie, l'arithmétique et la psychophysiologie.
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Heim, Eugene Henry DeWendt. "Development of Methods for Improved Data Integrity and Efficient Testing of Wind Tunnel Models for Dynamic Test Conditions in Unsteady and Nonlinear Flight Regimes." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31050.
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Todayâ s high performance aircraft are operating in expanded flight envelopes, often maneuvering at high angular rates at high angles-of-attack, even above maximum lift. Current aerodynamic models are inadequate in predicting flight characteristics in the expanded envelope, such as rapid aircraft departures and other unusual motions. Unsteady flows of aircraft are of real concern. The ability to accurately measure aerodynamic loads directly impacts the ability to accurately model and predict flight. Current wind tunnel testing techniques do not adequately address the data fidelity of a test point under the influence of fluctuating loads and moments. Additionally, forced oscillation test techniques, one of the primary tools used to develop dynamic models, do not currently provide estimates of the uncertainty of the results during an oscillation cycle. Further, in testing models across a range of flight conditions, there are frequently parts of the envelope which are well behaved and require few data points to arrive at a sound answer, and other parts of the envelope where the responses are much more active and require a large sample of data to arrive at an answer with statistical significance. Currently, test methods do not factor changes of flow physics into data acquisition schemes, so in many cases data are obtained over more iterations than required, or insufficient data may be obtained to determine a valid estimate. Methods of providing a measure of data integrity for static and forced oscillation test techniques are presented with examples. A method for optimizing required forced oscillation cycles based on decay of uncertainty gradients and balance tolerances is also presented.Master of Science
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CAPPANERA, GIANLUCA. "Analisi fluidodinamica ed acustica di appendici palari per turbina eolica di piccola taglia e studio preliminare di sistema di accumulo in aria compressa." Doctoral thesis, Università Politecnica delle Marche, 2020. http://hdl.handle.net/11566/274610.
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Lo sviluppo tecnologico nel settore delle fonti rinnovabili, in particolare quello eolico, ha portato negli ultimi anni ad una forte presenza di aerogeneratori di grande e piccola taglia nelle zone rurali. In tali contesti applicativi, la problematica del rumore emesso dalle pale in rotazione è tuttora oggetto della ricerca scientifica mondiale. D’altra parte, in un panorama di transizione verso un sistema elettrico evoluto diviene cruciale l’applicazione di sistemi di stoccaggio dell’energia, pertanto lo studio di tecniche di accumulo alternative alle batterie è di assoluto interesse scientifico ed industriale. Il lavoro di ricerca è volto allo studio di appendici aerodinamiche note come Trailing-Edge Serrations, atte alla riduzione del rumore prodotto dalle pale di turbine eoliche, e allo studio preliminare di un sistema di accumulo, entrambi in applicazione agli aerogeneratori di piccola taglia. La campagna sperimentale ha visto dapprima la caratterizzazione fluidodinamica delle appendici effettuata in galleria del vento con test di tipo globale e locale, mediante l’impiego di un modello di ala con profilo NACA 642 014A ad alte prestazioni. I risultati hanno permesso di valutare le diverse qualità aerodinamiche di un tratto di pala eolica dovute alla presenza delle appendici allo scopo di prevederne l’impatto sulla produzione elettrica. I test sono proseguiti con la caratterizzazione acustica delle stesse appendici applicate stavolta ad un modello di pala rotante, posto in camera semi-anecoica. Grazie ad un set-up di misura appositamente progettato e ad innovativi algoritmi di localizzazione acustica è stata analizzata l’impronta sonora del modello con e senza appendici, in termini di emissione complessiva e mappatura delle sorgenti sonore. Il tutto è stato corredato dallo studio di un sistema di accumulo energetico di tipo “CAES” (Compressed Air Energy Storage) di taglia ridotta per il supporto alla produzione da fonte mini-eolica in ambiti di fornitura elettrica in zone remote.Recently, the technology development in renewable energy sector, especially for wind energy, has brought a wide presence of large and small wind turbines in rural areas. For these applications, noise emitted from rotating blades is a hot topic in worldwide scientific research. On the other hand, in the sight of an evolved electric system the delivery of energy storage systems is crucial. Thus, the study of storage techniques alternative to batteries is of absolute scientific and industrial interest. The research work here presented is aimed at the study of aerodynamic appendages known as Trailing-Edge Serrations (TES) conceived for wind turbine blades noise mitigation and at the preliminary evaluation of an energy storage system, both applicable to small wind turbines. The experimental campaign has firstly seen the fluid-dynamic study of TES from global and local points of view by the use of a fixed wing model with high performance NACA 642 014A airfoil, placed in the wind tunnel. Results allowed the evaluation of different aerodynamic performance due to the presence of the appendages, in order to foresee them impact on power production. Secondly, experiments proceeded with the acoustic characterization of TES applied to a rotating blade model placed in the semi-anechoic chamber. By a special measurement setup and the use of most recent algorithms for sound source localization, the acoustic footprint of the model with and without TES has been analysed, resulting in global noise emission and noise source mapping. The whole has been accompanied by a study of a Compressed Air Energy Storage (CAES) system of small size designed to support small wind turbine power production for electric supply of remote areas.
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Di, Nicola Federico. "Energy harvesting from piezoelectric devices embedded in a 3D printed wing." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9705/.
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This thesis work has been carried out at Clarkson University in Potsdam NY, USA and involved the design of a low elongation wing, consisting of parts made by polylactide (PLA) using the fused deposition model (FDM) technology of Rapid Prototyping, then assembled together in a thin aluminum spar. The aim of the research is to evaluate the feasibility of collecting electrical energy by converting mechanical energy from the vibration of the wing flutter. With this aim piezoelectric stripes were glued in the inner part of the wing, as well as on the aluminum spar, as monomorphic configuration.
During the phases of the project, particular attention was given to the geometry and the materials used, in order to trigger the flutter for low flow velocity.
The CAD software SolidWorks® was used for the design of the wing and then the drawings were sent to the Clarkson machine shop in order to to produce the parts required by the wing assembly.
FEM simulations were performed, using software MSC NASTRAN/PATRAN®, to evaluate the stiffness of the whole wing as well as the natural vibration modes of the structure. These data, in a first approximation, were used to predict the flutter speed.
Finally, experimental tests in the Clarkson wind tunnel facility were carried out in order to validate the results obtained from FEM analysis. The power collected by the piezoelectrics under flutter condition was addressed by tuning the resistors downstream the electronic circuit of the piezoelectrics.
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ORLANDO, ANDREA. "Full-scale monitoring of the wind-induced response of vertical slender structures, with fixed and rotating masses." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1049839.
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Nowadays, structural monitoring is gaining more and more attention in the field of wind engineering. On the wake of these developments, the thesis develops and applies a comprehensive structural monitoring procedure tailored for the validation and investigation in full-scale of the wind-induced response of vertical slender structures, with fixed and rotating masses. All the main aspects of the monitoring practice are discussed, regarding the number, location and type of the sensors, the acquisition and the transmission of the full-scale data, as well as the management of the experimental database by following an encoded scheme. In addition, the thesis highlights a number of issues typical of the monitoring activity that are not addressed in literature, providing inspiration to solve them. The defined procedure finds application in two monitoring campaigns launched by the Wind Engineering group at the University of Genoa: one slender structure with fixed masses (a light tower) and one slender structure with rotating masses (a small vertical axis wind turbine). As regards the light tower, a reference calculation model of the wind-induced response of poles and towers is selected from literature and is validated in full-scale. The input parameters needed for the application of the model are identified from experimental surveys, intersecting wind tunnel tests and dynamic identification techniques. The results highlight the goodness of the selected model and the large uncertainties associated to the input parameters. As regards the wind turbine, the full-scale data are used to investigate the contribution of the rotating parts to the dynamic behavior. In addition, the fatigue damage of the supporting tower is calculated under stationary and non-stationary excitation due to wind, turbine rotation, emergency stop and start. The results highlight the importance of the detail modeling, the fundamental role played by the non-stationary conditions and the errors committed when using conventional models of the load.
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Ferrareto, Johann Andrade. "Human comfort in tall building\'s subjected to wind-induced motion." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-17072017-105508/.
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Assessing tall building oscillation is a multidisciplinary area involving knowledge from different fields of study: structural engineering, wind engineering, reliability, and even human physiology, to name a few. With the modern high strength structural materials and the latest tendencies in tall buildings construction, new structural systems have become slender and new buildings have reached greater heights as time passes. This context leads to a situation where these slender structures are sensitive to dynamic effects from wind loads and where human comfort is often the prevailing criterion for the structural design. This multidisciplinary area with slender structural systems allied to economic and environmental aspects from building construction demands a better integration between the abovementioned fields in order to achieve both human comfort and sustainable buildings (from environmental and economic points of view). This thesis aims at connecting the \"weak links\" of the Davenport\'s chain of wind loading, discussing criteria from each field involved in the oscillation assessment of a tall building: dynamic analysis, finite element modelling, wind climate modelling and comfort assessment. The axis of investigation intends to bring precision to the procedure, whilst creating a reliable set of criteria to perform a dynamic response assessment from the wind tunnel testing of tall buildings. This thesis also aims at connecting these fields of study by bringing understanding from each one of them to all the others, and at validating multidisciplinary interactions in the Davenport\'s chain. Finally, a wide dispersion of results is obtained for two different tall buildings in São Paulo. This dispersion serves to corroborate the deficient integration between these fields of study and to present a set of criteria that brings precision to the procedure, whilst allowing more economic and sustainable designs.O estudo das oscilações de edifícios altos sob ação do vento é uma área multidisciplinar que envolve conhecimentos de diferentes campos de estudo: engenharia estrutural, engenharia de vento, confiabilidade e até fisiologia humana, para citar apenas alguns. Em paralelo, a criação de novos materiais de construção de alta resistência, aliados às últimas tendências na construção de edifícios altos, permite sistemas estruturais cada vez mais esbeltos aplicados a edifícios cada vez mais altos. Este contexto leva a uma situação em que estes sistemas estruturais são sensíveis aos efeitos dinâmicos das cargas de vento e onde o conforto humano é frequentemente o critério preponderante para o projeto estrutural. Esta área multidisciplinar, com seus sistemas estruturais esbeltos, aliada aos aspectos econômicos e ambientais da construção de edifícios altos, exige uma melhor integração entre os campos acima referidos para se alcançar conforto humano em edifícios sustentáveis (tanto do ponto de vista ambiental quanto do econômico). Esta tese tem como eixo de investigação os \"elos fracos\" da corrente de cargas de vento de Davenport e discute os critérios de cada campo envolvido na avaliação das oscilações de um edifício alto: análise dinâmica, modelagem de elementos finitos, modelagem probabilística de vento e avaliação de conforto. O eixo de investigação proposto visa a trazer precisão ao procedimento, criando um conjunto de critérios confiáveis para a avaliação da resposta dinâmica a partir de ensaios em túnel de vento de edifícios altos. Esta tese também visa a conectar estes campos de estudo, trazendo a compreensão de cada um deles para todos os outros e para validar as interações multidisciplinares na corrente de Davenport. Finalmente, uma grande dispersão de resultados é obtida para dois edifícios altos em São Paulo. Esta dispersão serve para corroborar a deficiência da integração entre estes campos de estudo e para apresentar um conjunto de critérios que traga precisão ao procedimento, permitindo, concomitantemente, projetos mais econômicos e sustentáveis.
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Kichkie, Nabil. "Comportement dynamique en lacet d'une eolienne a axe horizontal." Paris, ENSAM, 1987. http://www.theses.fr/1987ENAM0007.
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Determination de l'influence des parametres geometriques et aerodynamiques sur le comportement dynamique de la machine grace a la resolution du systeme d'equations differentielles qui caracterise le mouvement d'oscillation. Essais en soufflerie sur une maquette a l'echelle 1/3,5 permettant de determiner les couples de rappel ainsi que le coefficient de puissance et le comportement en lacet. Transposition des resultats de la maquette au prototype par l'application des lois de la similitude