Como o erro é inerente ao próprio processo de medida, e portanto nunca será completamente eliminado, deve-se buscar minimizá-lo, reduzindo ao máximo as fontes de erros grosseiros e sistemáticos. Devido à dificuldade de identificar com segurança as fontes desses erros e tendo o indício que, em grande parte, ocorrem devido às variações geométricas e às características construtivas dos modelos ensaiados, é apresentada, como proposta de ferramenta de auxílio à detecção desses erros, a construção de um modelo padrão aeronáutico. Devido às semelhanças geométricas com os modelos das aeronaves atualmente ensaiados no Túnel Aerodinâmico número dois (TA-2) do IAE, foi escolhido como modelo-padrão o M5 da série M do Office National DÉtudes et de Recherches Aérospatiales (ONERA) para ensaios de proficiência intra e interlaboratorial do TA-2 nesse tipo de ensaio. O contexto que possibilitou a recomendação da proposta está descrito na primeira parte do presente trabalho, que trata do controle e melhoria da infraestrutura. Quanto à infraestrutura, propõe-se a melhoria das instalações e o conhecimento e controle sobre o escoamento do túnel. Sobre controle na execução dos ensaios intralaboratoriais são obedecidos os quesitos da NBR 17025 e da NBR 15100. Esses ensaios intralaboratoriais fornecem a reprodutividade dos ensaios de curto termo, isto é, ensaios executados numa mesma campanha ou próximos que forneceram resultados comparáveis aos de grandes complexos de túneis do primeiro mundo, porém a reprodutividade de longo termo, quando observadas condições diferentes de equipamentos, montagem, entre outros, nota-se uma característica de erros sistemáticos. / As the error is inherent to the proper process of measure, and therefore never completely it will be eliminated, it must be searched to minimize it, reducing to the maximum the sources of gross errors and systematic. Due to difficulty to identify with security the sources of these errors and having the indication that, to a large extent, occurs due to the geometric variations and the constructive characteristics of the assayed models, it is presented, as proposal of tool of aid to the detention of these errors, the construction of a model aeronautical standard. Had to the geometric similarities with the models of the aircraft currently assayed in the Wind tunnel number two (TA-2) of the IAE, the M5 of M serie of the Office National DÉtudes et de Recherches Aérospatiales (ONERA) it was chosen as model-standard for proficiency assays intra and interlaboratorial of the TA-2 in this type of assay. The context that made possible the recommendation of the proposal is described in the first part of the present work, that deals with the control and improvement of the infrastructure. About to the infrastructure, it is considered improvement of the installations and the knowledge and control on the draining of the tunnel. On control in the execution of the intralaboratoriais assays the questions of NBR 17025 and NBR 15100 are obeyed. These intralaboratoriais assays supply the reprodutividade of the assays of short term, that is, assays executed in one same campaign or next that they had supplied resulted comparable to the ones of great complexes of tunnels of the first world, however the reprodutividade of long term, when observed different conditions of equipment, assembly, among others, a characteristic of bias quality controls is noticed.

Previously, the concept of the tolerant wind tunnel, developed in the Department of Mechanical Engineering, U. B. C., was tested only for stationary models. In the present study, the concept is investigated for unsteady airfoil motion. The new wind tunnel test section, using the opposite effects of solid and open boundaries, is a new approach to reduce wall blockage effects. Consisting of vertical airfoil slats uniformly spaced on both side walls in the test section, it is designed to produce a nearly free-air test environment for the test model, which leads to negligible or small corrections to the experimental results. The performance of this wind tunnel for unsteady model testing is examined experimentally with a two-dimensional NACA 0015 airfoil in a simple plunging sinusoidal motion. The airfoil is mounted vertically in the center plane of the test section between solid ceiling and floor. An oscillating table is designed to give the airfoil an accurate plunging sinusoidal motion. A full range of open area ratio is tested by varying the number of slats mounted inside the side walls. Pressure distribution along the airfoil surface and displacement of the airfoil are measured as functions of time by a data acquisition system designed for this research. Lift and moment are obtained by integration of the pressure distribution at every time increment. Using a numerical model based on the singularity distribution method, the free air case results for a NACA 0015 airfoil in the same unsteady motion are obtained. Comparison with the linear theory results by Sears¹ are discussed. Comparing with the numerical and the linear theory results, the experimental investigation shows that the new test section produces low-correction data. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Much research and experiments have gone into studying idealized wing-body junction flows and their impact on horseshoe vortex and wake formation.  The vortices have been found to generate regions of high surface pressure fluctuations and turbulence that are detrimental to structural components and acoustics.  With the focus in the military and commercial industry on reducing the acoustical impact of aircraft and their engines, very little research has been done to examine the potential impact wing-body junctions may have on acoustics, especially for high lifting bodies such as propellers.  Two similar tests were conducted in the Virginia Tech Open Jet Wind Tunnel where boundary layer measurements, oil flow visualizations, acoustic linear array and surface pressure fluctuation measurements of a baseline Rood airfoil model and two novel junction fairing designs were all taken.  Boundary layer measurements were taken at four locations along the front half of the flat plate and the profiles were shown to be all turbulent despite the low Reynolds number of the flow, (test 1: Re_"<1400, test 2: Re_"<550).  Oil flow visualizations were taken and compared to those of previous researchers and the location of separation and line of low shear along with the maximum width of the wake and width of wake at the trailing edge all scaled relatively well with the Momentum Deficit Factor, defined for wing-body junction flows [Fleming, J. L., Simpson, R. L., Cowling, J. E. & Devenport, W. J., 1993. An Experimental Study of a Turbulent Wing-Body Junction and Wake Flow. Experiments in Fluids, Volume 14, pp. 366-378. ].  A linear microphone array was used to estimate the directivity of the facility acoustic background noise to be used to improve background subtraction methods for surface pressure fluctuation measurements.  Surface pressure fluctuation spectra were taken ahead of the leading edge of the plate and along the surface of the models.  These showed that the fairings reduced pressure fluctuations along the plate upstream of the leading edge, with fairing 1 reducing them to clean tunnel flow levels.  On the surface of the models, the fairings tended to reduce low frequency (<1000Hz) pressure fluctuation peaks when compared to the baseline model and increase the pressure fluctuations in the high frequency range.  Simple scaling arguments indicate that this spectral change may be more beneficial than detrimental as low frequency acoustics especially those between 800 Hz and 1200 Hz are the frequencies that humans perceive as the loudest noise levels.  Scaling the frequencies measured to those of full scale applications using Strouhal numbers show that frequencies below 1000 Hz in this experiment result in frequencies at the upper limit of the human hearing frequency range.  Low frequency acoustic waves also tend to travel farther and high frequency acoustic waves are more apt to be absorbed by the surrounding atmosphere. / Master of Science

An experimental study of active control of fully separated flow over a symmetrical circular-arc airfoil at high angles of attack was performed. The experiments were carried out in a low-speed, open circuit wind tunnel. Angles of attack from 10 to 40 degrees were tested. Low-power input, unsteady excitation was applied to the leading or trailing edge shear layers. The actuation was provided by the periodic oscillation of a 4-percent-chord flap placed on the suction side of the airfoil and facing the sharp edge. Vortex-shedding frequencies were measured and harmonic combinations selected as the applied actuator frequencies. Pressure measurements over the airfoil show that the control increased the normal force coefficient by up to 70%. This supports the idea of vortex capture in the time-averaged sense, enhancing the lift on the airfoil by managing the shear layer roll up. The results indicate the viability of the control of large-scale flow fields by exploiting the natural amplification of disturbances triggered by small-scale actuators. The application of flow control on sharp-edged aircraft wings could lead to improved maneuverability, innovative flight control and weight reduction. These can be achieved by inexpensive, low-power, rugged actuators. / Master of Science

This thesis deals with the problems of scaling aerodynamic data from wind tunnel conditions to free flight. The main challenges when this scaling should be performed is how the model support, wall interference and the potentially lower Reynolds number in the wind tunnel should be corrected. Computational Fluid Dynamics (CFD) simulations have been performed on a modern transonic transport aircraft in order to reveal Reynolds number effects and how these should be scaled accurately. This investigation also examined how the European Transonic Wind tunnel (ETW) twin sting model support influences the flow over the aircraft. In order to further examine Reynolds number effects a MATLAB based code capable of extracting local boundary layer properties from structured and unstructured CFD calculations have been developed and validated against wind tunnel measurements. A general scaling methodology is presented. / QC 20101123

The Turbulent Heat Transfer Test Facility (THTTF) has been refurbished and the data acquisition system upgraded. The THTTF is now controlled by a LabView 4.1 program which replaces the old program in BASIC. Heat transfer data acquired using this new program is presented as Stanton number distributions. The new data set is compared to previously reported data obtained with this facility and other wellepted published data. This project has successfully qualified the THTTF for zero-pressure gradient, isothermal wall temperature, incompressible boundary-layer flow over smooth flat plates without transpiration. The THTTF is now set to accommodate modifications which will facilitate heat transfer investigations with high freestream turbulence.

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With a look towards the future, which involves a push towards utilizing renewable energy sources and cementing energy independence for future generations, the design of more efficient aircraft and novel energy systems is of utmost importance. This dissertation looks at leveraging some of the benefits offered by inflatable wings for use in tethered kite-like systems towards the goal of designing a High Altitude Aerial Platform (HAAP). Uses of such a system include Airborne Wind Energy Systems (AWES), among others. The key bene- fit offered by such wings is their lightweight construction and durability, but challenges to aerodynamic performance arise out of their flexible nature and non-standard airfoil profile. Studying the aerodynamic behavior of such wings forms the critical focus of this research. This effort primarily encompasses an experimental investigation of two swept, tethered, inflatable wings conducted in the Virginia Tech Stability Wind Tunnel, and numerical CFD computations of these wings. The experiment was conducted in the modular wall configuration of the anechoic test section at speeds ranging from 15 − 32.5 m/s for three different tether attachment configurations and wings constructed out of two different fabric materials. Along with static aeroelastic deformation data using a 3D photogrammetry system, aerodynamic measurements were taken in the form of Pitot and static pressure measurements in the wake of the wing, force and moment measurements at the base of the mount, and tension measurements at the tether attachment locations. This provides a data set for validating static aeroelastic modeling approaches for such a system and highlights the dramatic effect of the variability in test configuration on the wing's aerodynamics. In addition to the wind tunnel tests, 3D steady RANS CFD computations of the rigid 3D scanned inflatable wing geometry were conducted in the wind tunnel environment for these configurations to validate the CFD modeling approach and highlight the level of detail necessary to accurately characterize the wing aerodynamic performance. Static aeroelastic deformation data from the 3D photogrammetry system, at a speed of 27.5 m/s, were also used to deform the 3D scanned inflatable wing geometry, and RANS CFD computations of this deformed inflatable wing were conducted at a wind tunnel speed of 27.5 m/s. Several turbulence models were investigated and comparisons were made with the wind tunnel test data. Good agreement was found with experimental data for the forces and moments and wake Pitot pressure coefficient contours. Comparisons were also made with the rigid wing CFD computations at the same tunnel speed of 27.5 m/s to illustrate the effect of static aeroelastic deformations on the aerodynamic performance, wake Pitot pressure coefficient contours and wing-tip vortex structures, of these flexible inflated wings. In effect, this research utilizes the synergy be- tween wind tunnel experiments and numerical CFD computations to study the flow behavior over inflatable wings and provide a comprehensive verification and validation approach for modeling such complex systems. / Doctor of Philosophy / With a look towards the future, which involves a push towards utilizing renewable energy sources and cementing energy independence for future generations, the design of more efficient aircraft and novel energy systems is of utmost importance. This dissertation looks at leveraging some of the benefits offered by inflatable wings for use in tethered kite-like systems towards the goal of designing a High Altitude Aerial Platform (HAAP). Uses of such a system include Airborne Wind Energy Systems (AWES), among others. The key benefit offered by such wings is their lightweight construction and durability, but challenges to aerodynamic performance arise out of their flexible nature and non-standard airfoil profile. Studying the aerodynamic behavior of such wings forms the critical focus of this research. This effort primarily encompasses an experimental investigation of two swept, tethered, inflatable wings conducted in the Virginia Tech Stability Wind Tunnel, and computer simulations of the aerodynamic flow over these wings. The experiment was conducted in the modular wall configuration of the anechoic test section at speeds ranging from 15 − 32.5 m/s for three different tether attachment configurations and wings constructed out of two different fabric materials. Along with measurements of the wing deformations using a 3D photogrammetry system, aerodynamic measurements were taken in the form of pressure measurements in the wake of the wing, force and moment measurements at the base of the mount, and tension measurements at the tether attachment locations. This provides a data set for validating static aeroelastic modeling approaches for such a system and highlights the dramatic effect of the variability in test configuration on the wing's aerodynamics. In addition to the wind tunnel tests, detailed computer simulations of the scanned inflatable wing geometry were conducted in the wind tunnel environment for these configurations to validate the computational modeling approach and highlight the level of detail necessary to accurately characterize the wing aerodynamic performance. The wing deformation data from the 3D photogrammetry system, at a speed of 27.5 m/s, were also used to deform the scanned inflatable wing geometry, and computer simulations of this deformed inflatable wing geometry were conducted at a wind tunnel speed of 27.5 m/s. Good agreement was found between the experimental and computational forces and moments and wake Pitot pressure coefficient contours. Comparisons were also made with the undeformed wing computations at the same tunnel speed of 27.5 m/s to illustrate the effect of wing flexibility on the aerodynamic performance. In effect, this research utilizes the synergy between wind tunnel experiments and numerical CFD computations to study the flow behavior over inflatable wings and provide a comprehensive verification and validation approach for modeling such complex systems.

To solve traffic congestion in Bangkok, the Bangkok Mass Transit system (BTS) constructed an overhead rail system with 24 stations. The BTS train station, S2, in this study area covers Silom road and obstructs the air pollutant dispersion in a congestion area. The 1: 200 physical model of the buildings along Silom road with the train station, S2, was simulated in this research to determine the air pollutant dispersion in the train station area. A tracer gas (CO₂) was emitted from a simulated line source with emission rates of 0.383, 0.681, 1.293, 2.586, 5.177 and 10.77 mg/min to simulate actual pollutant emission rates. The CO₂ gas was sampled at 55 locations in the model. The Kriging method was used to interpolate the data in the study area. . Emission rates were used to make the difference between measured CO₂ in the model area and ambient CO₂ large enough to be differentiated. Regression Analysis was used to relate analytically the mass emission rate to the CO₂ concentration. The results indicate that the maximum CO concentrations exceed the 30 ppm Bangkok standard along the Southeast side of Silom Road at the passenger platform level. Drivers will acquire more harmful levels of CO than pedestrians at street level, especially near the Southwest end of the train station. NO₂ concentrations do not exceed the standard (0.17 ppm) at street level. The highest predicted VOC is 1.05 ppm. These results may be used in the future for numerical modeling study. / Master of Science

A supersonic wind tunnel, with a 20" x 20'" test section cross sectional area, was designed and constructed at the Techsburg Wind Tunnel Facility in order to determine the lift and drag on irregularly shaped fragments in supersonic flow. Prior to beginning the wind tunnel design process, a blowdown analysis model was created in order to determine the influence of a number of parameters on tunnel run time and test gas properties throughout the tunnel circuit. The design of the settling chamber, test section, supersonic nozzles, diffuser, and exhaust are presented in this thesis. Diffuser performance has a large influence on wind tunnel efficiency and run time. Therefore, significant efforts should be taken in order to attain the highest possible pressure recovery within the diffuser. The design of wind tunnel components, as well as their stress analysis, was conducted using SolidWorks. The control valve and silencer were sized and selected for the expected tunnel operating conditions. Since the control valve tends to encompass a significant portion of the overall tunnel cost, care must be taken to ensure it has a large enough flow capacity to produce the desired test conditions. Also, attempts must be made to accurately predict the total pressure loss through the silencer, since this loss can have a large impact on the total pressure ratio necessary to produce the design Mach number. Upon completion of the design process, the supersonic wind tunnel was assembled, and shakedown testing was conducted. During shakedown testing it was determined that the wind tunnel was capable of producing Mach 2 flow in the test section. Following shakedown testing, a flow survey was conducted in order to ensure uniform Mach number flow exists throughout the region occupied by the fragments. Based on the flow survey it was determined that within the middle 60% of the test section, the average Mach number was 1.950 and varied by only 0.56% within this region. Two irregularly shaped fragments were tested at Mach 2 flow, over an effective 360° pitch sweep, with wind tunnel runs performed every 10 degrees. Based on the measured force data for both fragments, the lift appeared to follow a sinusoidal curve, with minimum values at 0, 90, and 180° balance pitch angle, and maximum values occurring around 45 and 135° pitch angle. The drag force was observed to follow a gradual curve with minimum values at 0 and 180° balance pitch angle, as expected since the fragment presented area is generally least in this orientation. The maximum drag was found to occur at a balance pitch angle of 90°, once again as expected since the fragment presented area is generally greatest at this angle. It was also observed that the fragment drag tended to be greater for a fragment orientation which places the concave side of the fragment into the direction of the flow. / Master of Science