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This study investigated the applicability of Particle Image Velocimetry (PIV) as a velocity measurement technique for use in wind tunnel flows. To carry out the investigation, a small scale wind tunnel was designed and built to be used specifically with PIV. The tunnel employed a novel contraction geometry which was compared to six other contraction designs using a computational fluid dynamics (CFD) software package. The wind tunnel configuration allowed for full optical access in the test section to allow for PIV measurements in three dimensions. The calibration and characterization of the flow quality within the wind tunnel were performed using PIV. Velocity measurements were obtained in the empty test section to assess the degree of uniformity, alignment, and turbulence at various test speeds. The longitudinal velocities were found to deviate by an average of 1. 8% along any given velocity profile. The flow was found to be well aligned with the test section walls, deviating by no more than &plusmn;0. 20° in most cases. As well, the turbulence levels in the test section were found to be low, with average intensities of 2. 0% and 0. 5% in the longitudinal and transverse directions, respectively. Following the characterization of the flow in the empty wind tunnel, a square cylinder was placed in the test section and PIV measurements were performed at a Reynolds number of 21,400. Mean velocities and turbulence intensities measured around the square cylinder were found to compare well with previous works conducted at similar Reynolds numbers in water flows. As a final validation of the wind tunnel/PIV system, measurements were made of the flow over a 1:18 scale Formula One racecar model at a free stream velocity of 40 <i>m/s</i>. The PIV system collected a large quantity of velocity information around the model, providing insight into the aerodynamic aspects of racecars such as downforce devices and vehicle draughting. The experiments performed in this study led to the conclusion that PIV is indeed a measurement technique with high potential for use in small wind tunnels, providing more spatially resolved velocity data than any other known measurement technique. The advancement of digital camera technology will make PIV a more practical measurement technique for use in larger wind tunnels as well.

Currently, wind energy presents an excellent opportunity to satisfy the growing demand without the supply and environmental problems associated with conventional energy. The engineering in wind turbines is not fully mature. There are still phenomenon, particularly dynamic stall, that cannot accurately be modeled or controlled. Dynamic stall contributes to fatigue stress and premature failure in many turbine components. The three dimensionality of dynamic stall makes these structures unique for wind turbines. Currently, flow visualization of dynamic stall on a wind turbine rotor has not been achieved. These visualizations can reveal a lot about the structures that contribute to dynamic stall. Particle Image Velocimetry (PIV) is a powerful experimental technique that can take multiple non-intrusive flow measurements simultaneously of planar flow. Using high-speed cameras time resolved PIV can reveal the transient development of a given flow field. This technique is ideally suited to gain a better understanding of dynamic stall. A custom wind turbine is being built at the University of Waterloo to allow such measurements on the blade. A high speed camera is mounted on the hub and will take measurements within the rotating domain. Mirrors are used so that laser illumination rotates with the blade. The wind turbine will operate in controlled conditions provided by a large wind tunnel. High speed pressure data acquisition will be used in conjunction with PIV to get an understanding of the forces associated with the flow structures. Computational fluid dynamics was used to size the rotor within the wind tunnel. Laser based measurements required special considerations for stiffness. Many revealing experiments will be made possible by this apparatus. First, the flow structures responsible for the various forces can be identified. Quantitative measurements of the flow field will identify the development of the stall vortex. The quantified flow structures can be used verify and improve models. The high spatial resolution of PIV can map the three dimensional flow structure in great detail. The experimental apparatus is independent of the blade geometry, as such multiple blades can be used to identify the effect of blade geometry. Finally flow control research in the field of aviation can be applied to control dynamic stall.

This study investigated the applicability of Particle Image Velocimetry (PIV) as a velocity measurement technique for use in wind tunnel flows. To carry out the investigation, a small scale wind tunnel was designed and built to be used specifically with PIV. The tunnel employed a novel contraction geometry which was compared to six other contraction designs using a computational fluid dynamics (CFD) software package. The wind tunnel configuration allowed for full optical access in the test section to allow for PIV measurements in three dimensions. The calibration and characterization of the flow quality within the wind tunnel were performed using PIV. Velocity measurements were obtained in the empty test section to assess the degree of uniformity, alignment, and turbulence at various test speeds. The longitudinal velocities were found to deviate by an average of 1. 8% along any given velocity profile. The flow was found to be well aligned with the test section walls, deviating by no more than &plusmn;0. 20° in most cases. As well, the turbulence levels in the test section were found to be low, with average intensities of 2. 0% and 0. 5% in the longitudinal and transverse directions, respectively. Following the characterization of the flow in the empty wind tunnel, a square cylinder was placed in the test section and PIV measurements were performed at a Reynolds number of 21,400. Mean velocities and turbulence intensities measured around the square cylinder were found to compare well with previous works conducted at similar Reynolds numbers in water flows. As a final validation of the wind tunnel/PIV system, measurements were made of the flow over a 1:18 scale Formula One racecar model at a free stream velocity of 40 <i>m/s</i>. The PIV system collected a large quantity of velocity information around the model, providing insight into the aerodynamic aspects of racecars such as downforce devices and vehicle draughting. The experiments performed in this study led to the conclusion that PIV is indeed a measurement technique with high potential for use in small wind tunnels, providing more spatially resolved velocity data than any other known measurement technique. The advancement of digital camera technology will make PIV a more practical measurement technique for use in larger wind tunnels as well.

Currently, wind energy presents an excellent opportunity to satisfy the growing demand without the supply and environmental problems associated with conventional energy. The engineering in wind turbines is not fully mature. There are still phenomenon, particularly dynamic stall, that cannot accurately be modeled or controlled. Dynamic stall contributes to fatigue stress and premature failure in many turbine components. The three dimensionality of dynamic stall makes these structures unique for wind turbines. Currently, flow visualization of dynamic stall on a wind turbine rotor has not been achieved. These visualizations can reveal a lot about the structures that contribute to dynamic stall. Particle Image Velocimetry (PIV) is a powerful experimental technique that can take multiple non-intrusive flow measurements simultaneously of planar flow. Using high-speed cameras time resolved PIV can reveal the transient development of a given flow field. This technique is ideally suited to gain a better understanding of dynamic stall. A custom wind turbine is being built at the University of Waterloo to allow such measurements on the blade. A high speed camera is mounted on the hub and will take measurements within the rotating domain. Mirrors are used so that laser illumination rotates with the blade. The wind turbine will operate in controlled conditions provided by a large wind tunnel. High speed pressure data acquisition will be used in conjunction with PIV to get an understanding of the forces associated with the flow structures. Computational fluid dynamics was used to size the rotor within the wind tunnel. Laser based measurements required special considerations for stiffness. Many revealing experiments will be made possible by this apparatus. First, the flow structures responsible for the various forces can be identified. Quantitative measurements of the flow field will identify the development of the stall vortex. The quantified flow structures can be used verify and improve models. The high spatial resolution of PIV can map the three dimensional flow structure in great detail. The experimental apparatus is independent of the blade geometry, as such multiple blades can be used to identify the effect of blade geometry. Finally flow control research in the field of aviation can be applied to control dynamic stall.

An experimental wind tunnel study on the dynamic response of a 300 m tall guyed telecommunication mast under various wind loads was undertaken at the Boundary Layer Wind Tunnel Laboratory (BLWTL) in the University of Western Ontario, London, Canada. Although the dynamic response of guyed masts subjected to turbulent wind loads has been routinely analyzed using a number of numerical models, typically in the frequency domain, limited experimental verification of the dynamic analysis results has been performed. Full-scale measurements, where available, have proven to be difficult to correlate with analytical models due to the tremendous uncertainty inherent in field measurements. As a result, the need for systematic validation of existing analytical models remains.<p>In this investigation, a representative 300 m tall guyed telecommunication mast has been designed and modeled to an appropriate scale. Based on Canadian Standard CSA S37-01, and an empirical study on 41 existing guyed masts, the 300 m tall guyed mast was designed using wind load conforming to representative Canadian climate data obtained from National Building Code of Canada (NBCC 1995). Appropriate properties for the dynamically scaled full aeroelastic model were derived from the 300 m tall prototype guyed mast, which was intended to represent a realistic guyed mast for broadcasting applications in Canada.<p>The wind tunnel test of the guyed mast model was carried out in both open country and over water exposures, simulating medium and low turbulence flow conditions, respectively. Dynamic response characteristics measured during the wind tunnel tests have been analysed and summarized, including dynamic displacements, bending moments, response spectra and peak factors, as well as natural frequencies, mode shapes and structural damping. Comparisons have been made with predictions obtained from an existing frequency domain analysis model. <p>The wind tunnel test results show that good agreement was generally achieved between the frequency domain analytical model and the wind tunnel model with respect to both the magnitude and distribution of the monitored responses. It was found that measured dynamic bending moments were distributed in a fairly uniform manner over the mast height, and that mean (static) bending moments exhibit large variations, along with near-zero response zones at points of contraflexure. It was also found that nonlinear damping effects, associated with vibrations of the highly slackened leeward guys on the upper levels of the mast, may be beneficial in reducing dynamic mast displacements. <p>The spectrum studies indicated that lowest modes were dominated by large guy movements at top guy level and small mast movements, the middle modes were characterized by coupled effects between the guyed cables and mast, meanwhile the highest modes involved significant mast movements with little guy vibration. It is evident that the top of the mast displacement are dominated by the first and second modes.

Three flight simulator experiments examined how a health monitoring system may aid pilots in detecting flight control faults. The first experiment introduced an unexpected fault in the flight control system during an approach to a fictitious airport. The second experiment used a factorial design of (1) presence ?? notof a Fault Meter display and (2) presence ?? not ?? an Alerting System, which could have one or two phased alerts. In half the runs, a fault was triggered at some point, and pilot response was recorded. The next experiment comprised one flight in which pilots were given a false alarm by these systems, testing for automation bias. No consistent pilot response was found to the faults, with pilots sometimes successfully landing the aircraft, sometimes immediately or eventually initiating a go-around, and sometimes loosing aircraft control and crashing. The pilots were not able to identify the fault in 11% of the cases. Tunnel tracking error increased following the faults and the false alarm, suggesting it may be both a manifestation of attempts to diagnose a fault and a cue to pilots of a problem. Finally, the triggering of a false alarm showed the existence of automation bias induced after a small number of interactions with the HMS.

Previous studies have demonstrated that EPA approved federal reference method (FRM) samplers can substantially misrepresent the fractions of particles being emitted from agricultural operations due to the relationship between the performance characteristics of these samplers and existing ambient conditions. Controlled testing in a wind tunnel is needed to obtain a clearer understanding and quantification of the performance shifts of these samplers under varying aerosol concentrations, wind speeds and dust types. In this study, sampler performance was tested in a controlled environment wind tunnel meeting EPA requirements for particulate matter (PM) sampler evaluation. The samplers evaluated included two low-volume PM10 and Total Suspended Particulate (TSP) pre-separators. The masses and particle size distributions (PSDs) obtained from the filters of tested samplers were compared to those of a collocated isokinetic sampler. Sampler performance was documented using two parameters: cut-point (d_50) and slope. The cut-point is the particle diameter corresponding to 50% collection efficiency of the pre-separator while the slope is the ratio of particle sizes corresponding to cumulative collection efficiencies of 84.1% and 50% (d_84.1/d_50) or 50% and 15.9% (d_50/d_15.9) or the square root of 84.1% and 15.9% (d_84.1/d_ 15.9). The test variables included three levels of wind speeds (2-, 8-, and 24-km/h), five aerosol concentrations varying from 150 to 1,500 mu g/m3 and three aerosols with different PSDs (ultrafine Arizona Road Dust (ARD), fine ARD and cornstarch). No differences were detected between the performance of the flat and louvered FRM PM10 samplers (a = 0.05). The mean cut-point of both the PM10 samplers was 12.23 mu m while the mean slope was 2.46. The mean cut-point and slope values were statistically different from the upper limit of EPA-specified performance criteria of 10.5 mu m for the cut-point and 1.6 for the slope. The PM10 samplers over-sampled cornstarch but under-sampled ultrafine and fine ARD. The performance of the dome-top TSP sampler was close to the isokinetic sampler, and thus it can be used as a reference sampler in field sampling campaigns to determine true PM concentrations. There were large variations in the performance of the cone-top TSP samplers as compared to the isokinetic sampler. Dust type and wind speed along with their interaction had an impact on sampler performance. Cut-points of PM10 samplers were found to increase with increasing wind speeds. Aerosol concentration did not impact the cut-points and slopes of the tested samplers even though their interaction with dust types and wind speeds had an impact on sampler performance.

Low disturbance wind tunnels, such as the Klebanoff–Saric Wind Tunnel (KSWT), offer an ideal environment to study boundary layer transition. In particular, the leading-edge receptivity of sound can be measured by creating acoustic disturbances that interact with the leading edge of a model to create Tollmien–Schlichting Waves. The magnitude and composition (sound, turbulence) of the background disturbances can affect these experiments, so the background disturbances should be minimized and documented thoroughly. The purpose of this thesis is to document the background acoustic signature of the KSWT and describe infrastructure upgrades for acoustic receptivity experiments. The measurements presented in this thesis will support future receptivity measurements in the KSWT. Microphone measurements revealed several important acoustic features in the tunnel. Cross correlations showed that two sources of low-frequency unsteadiness (the extended diffuser and corner two) create large pressure fluctuations that dominate the pressure spectrum. Directional separation of waves in the test section revealed that motor and blade passing noise travels primarily upstream into the test section. Finally, the acoustic treatments in the plenum are effective at removing sound from the tunnel. A wall of speakers was installed in the plenum to enable acoustic receptivity experiments. The speakers create both the primary downstream traveling waves and reflected upstream traveling waves in the test section. An adaptive closed loop control system was installed to reduce the amplitude of the reflected waves during acoustic forcing. Although the performance of the control system is frequency dependent, the technique was implemented successfully. The reduction in the diffuser reflection will increase the quality of future acoustic receptivity experiments in the KSWT.

The influence of the surface excavation and loading on the existing tunnels has been investigated using a Finite Element Method program, Plaxis 3D Tunnel. A parametric study has been carried out where the parameters were the depth of the surface excavation, the eccentricity of the excavation with respect to the tunnel axis, the height of the embankment fill and the stiffness of the soil. It is found that, excavations over the existing tunnels have a negative effect on the tunnel lining capacity since the unloading due the excavation reduces the normal forces and increases the bending moments. On the other hand, it is found that surface loading within the limits considered in this study is not critical in terms of the tunnel stability due to the increase in normal forces and decrease in bending moments.