Wind Tunnel test

Wind tunnel testing has been carried out on nine-knitted single jersey fabrics (100% polyester) using cylinder and leg models to determine its aerodynamic behaviour over a range of speeds (20–80 km/h) representative of sports activities. Strong correlation between fabric manufacturing (cover factor) and fabric roughness and aerodynamic parameters has been established. Similar aerodynamic behaviour of fabrics was observed when tested on

Vortex-induced vibration of bridges happens at a relatively low wind speed and while vehicles often run on a bridge at that wind speed. Thus, it is necessary to study how the vehicles influence vortex-induced vibration of vehicle-bridge systems. Based on the project of Shanghai Bridge over Yangtse River, the wind tunnel test for vortex-induced vibrations of vehicle-bridge system of a 1:60 model is presented. The wind tunnel test is introduced in detail including the equipments, test procedures and discussion of results. The results show that the vehicles have much influence on vortex-induced vibration of vehicle-bridge system for the Shanghai Bridge over Yangtse River. With speed increasing, the displacement of the bridge with vehicles fluctuates larger than that of the bridge without vehicles. The frequencies of vibration could be divided into three stages, vertical vibration frequency for the first stage, torsional vibration frequency for the second stage, and suspension system vi...

The common challenge of all aerospace advancements is greening the air transport. This led the recent research programs towards the study of 'metamorphic' wing structures, capable of adapting their geometry to the different conditions of flight. The development of morphing structures allows the reduction of drag and the increase of range, together with the growth of load control effectiveness. In this context, the European research project SARISTU addressed the physical integration of smart and morphing structural concepts, by implementing them on a true scale outer wing belonging to a CS-25 category aircraft finally tested in a large Wind Tunnel. In the framework of SARISTU project, the design of an Adaptive Trailing Edge Device was developed. The morphing skin concept consisted of a segmented skin, with aluminum and silicone foam strips covered by a protective silicone top-layer. A two-bay demonstrator was tested inside the Wind Tunnel at the Department of Industrial Engineering of the University of Naples 'Federico II'; experimental analyses were performed in order to verify whether the silicone parts could show out of plane bumps induced by the aerodynamic loads occurring during the Wind Tunnel test campaign. A photogrammetric optic approach was adopted, in order to reach the aforementioned targets in a non-invasive way; such methodology was selected due the high resolution assured at a very low implementation costs. Obtained results allowed to confirm the demonstrator well done design and opened the doors to the next experimental test campaign performed in TsAGI Russian Wind Tunnel, on the outer wing equipped with a five-bay demonstrator of the Adaptive Trailing Edge Device. © 2017 IEEE.

This work describes the design and construction of a fully adaptive aircraft configuration used as an experimental testbed for aerodynamic modeling and flight control. The adaptive model is designed to achieve large scale shape changes in order to investigate morphing for multi-mission UAVs. There are five independent planform changes along with independent twist control for each wing. Wind tunnel testing was conducted in Virginia Tech's Stability tunnel to analyze the aerodynamic characteristics and evaluate the usefulness of having a UAV with multiple configuration capability. Wind tunnel tests of various planform configurations indicate that different configurations yields minimum drag over a range of flight conditions.

This paper presents the activities performed to improve the aerodynamic performances of a two man bobsleigh. Performances during races depend on aerodynamic design and crew expertise. Bobsleigh shape design optimization has long been based on intuitive modifications driven by the individual experiences of the athletes. In this work, we exploit the techniques routinely used for race car aerodynamics optimization to find optimized aerodynamic configurations for the bobsleigh. This problem can be formulated as a constrained shape optimization since the final configuration must still comply with the regulations of the international bobsleigh federation (FIBT). We use reverse engineering techniques to get a digital model of the initial shape of the bobsleigh. Then, we add a simplified three dimensional model of the crew and we use a finite volume solver of Navier Stokes equation to simulate the flow around the bobsleigh and crew under many typical race conditions. Specifically, we simulate the flow around the bobsleigh moving either along a straight channel (with side walls) or along a bend at different velocities. Based on the detailed analysis of the aerodynamic forces acting on the bobsleigh, we evaluate the effect of bobsleigh clearance and nose shape on aerodynamic performances, identifying and testing alternative design modifications. Based on these ``virtual wind tunnel tests'', an optimized profile for the shell and wings has been identified. Finally, aerodynamic tests have been performed in a wind tunnel on a scaled model of the bobsleigh and on the full scale model with and without the crew. Experimental tests confirm the results of numerical simulations and give additional useful suggestions for fine aerodynamic optimization of bobsleigh and crew during races.

Reproductions of a 1903 and a 1904 Wright propeller have been tested in the Langley Full Scale Tunnel, and will be compared with the 1911 Wright brothers' "bent end" propellers that were developed during their 1905 testing campaign. Wind tunnel testing was completed on December 29, 2000 and the purpose of this paper is to give a status report.

This paper aims to highlight the wind tunnel testing techniques and the Computational Fluid Dynamics (CFD) studies on a scaled-down microlight model for its aerodynamic characteristics. The wind tunnel testing is conducted at a grace of Universiti Teknologi Malaysia-Open Loop Subsonic Tunnel facility with variations of angle of attack and flaps deflection angle. Wind tunnel corrections, such as 'blockage' effects, are considered during data reduction process in order to have results that will be almost precisely the same as in actual flight. In additional, the CFD simulation will be carried out using the software Fluent 6.1 on the model. Comparison of these two methods later depicts that the result obtained from the wind tunnel testing is agreeable with the result simulated by the CFD.

The data presented in this article were the basis for the study reported in the research articles entitled 'A validated design methodology for a closed loop subsonic wind tunnel' (Calautit et al., 2014) [1], which presented a systematic investigation into the design, simulation and analysis of flow parameters in a wind tunnel using Computational Fluid Dynamics (CFD). The authors evaluated the accuracy of replicating the flow characteristics for which the wind tunnel was designed using numerical simulation. Here, we detail the numerical and experimental setup for the analysis of the closed-loop subsonic wind tunnel with an empty test section.

This thesis would not have been possible without the support of many people. First of all I would like to thank my mentor Prof. Hrvoje Kozmar for suggesting this thesis in the first place and for being there for me all the way through to completing of this thesis.

The objective of the research in this paper was to maximise the amount of performance enhancing aerodynamic down-force generated by the 2005/2006 University of Auckland Formula SAE race car. This was done through a combination of physical modelling using a rolling road wind tunnel research facility and by using computational fluid dynamics. Computational fluid dynamic analysis was used for the design of the body and under-tray of the vehicle. Optimal design gave a lift coefficient of -0.9 from the under-tray. Simulations showed that when the exhaust was vented into two diffuser tunnels under the car, the downforce was increased by 35%. Half-scale vehicle modelling using the wind tunnel rolling road facility gave a lift coefficient of -2.4. In its optimal configuration, the aerodynamic load on the front and rear wheels respectively was able to be adjusted between 43% on the front and 57% on the rear to 33% on the front and 67 % on the rear by changing the angle of the foils. The drag...

Human beings flying with the help of aircrafts of various kinds have been able to fly for about one century. Although the flapping wings of animals served as an inspiration to pioneers of human flight, we don't really understand how they work. In this study, we employ the concept of four-bar linkage to design a flapping mechanism which simulates a flapping motion of a bird. Wind tunnel tests were performed to measure the lift and thrust of the mechanical membrane flapping wing under different frequency, speed, and angle of attack. It is observed that the flexibility of the wing structure will affect the thrust and lift force due to its deformation at high flapping frequency. The lift force will increase with the increase of the flapping frequency under the corresponding flying speed. For the same flapping frequency, the flying speed can be increased by decrease of the angle of attack with the trade of loosing some lift force. An angle of attack is necessary in a simple flapping motion in order to derive a lift force. The flapping motion generates the thrust to acquire the flying speed. The flying speed and angle of attack combine to generate the lift force for flying.

The primary objective of the insteady aerodynamics experiment was to provide information needed to quantify the full-scale, three-dimensional aerodynamic behavior of horizontal-axis wind turbines. This report is intended to familiarize the user with the entire scope of the wind tunnel test and to support the use of the resulting data.

Increasing number of billboard collapse during wind storms indicates the vulnerability of this structure subjected to wind force. Typical billboard structures have fundamental natural frequency about 1 Hz or higher. Therefore, all previous studies assumed that the dynamic response of billboard structure is dominated by quasi-static response. However, billboard structures may contain damping values low enough to provoke significant resonant response. Moreover, dynamic wind load can lead billboard structures to oscillate in the along-wind and torsional direction. Coupling of these two responses may give net stress at the supporting column of billboard structure higher than allowable limit. A rigid 1:100 scale pressure model of a billboard structure was tested at TU-AIT wind tunnel under simulated open terrain boundary layer wind flow. Dynamic response of the billboard structure to wind-induced drag force and torsion was obtained individually. Thereafter, significance of resonant response was determined and lateral-torsional coupled displacement response was calculated by numerically joining individual responses. Lastly, equivalent static force for all wind attack angles were applied to finite element model and stress at supporting column was obtained through analysis. The results obtained from this study showed that dynamic response to wind-induced torsion of billboard structure is dominated by resonant response. However, high aerodynamic damping suppressed resonant response to wind-induced drag force. Though, lateral-torsional coupled displacement response is found to be indistinguishable to translational response. Yet, this inconsequential response results in higher net stress than allowable limit at the supporting column of billboard structure.

The modern tiltrotor is an aircraft capable of efficient hover as well as high-speed forward flight. The large, flexible rotors needed for good hover performance are susceptible to an aeroelastic phenomenon known as whirl flutter in high-speed flight: high rotor inflow and the flexible nature of the rotors will result in negative aerodynamic damping when the tiltrotor is in airplane mode,
causing the coupled wing/rotor/pylon system to become unstable.

Traditionally, the tiltrotor whirl flutter margin has been increased through the use of thick wings of low aspect ratio, which
maximize the stiffness of the wings at the expense of increased structural weight and reduced aerodynamic efficiency. To increase the top speed of tiltrotors, new methods of analyzing and
mitigating the whirl flutter phenomenon must be developed.

This study focuses on the design and development of a semispan wind tunnel model that permits the testing of whirl flutter stability in a controlled, low-risk environment. The wind tunnel model was dynamically tested in the Penn State Hammond Low-Speed Wind Tunnel.

Five configurations were tested for modal damping variations with respect to tunnel speed. Two of these configurations ("Gen-2") were modified versions of the first-generation ("Gen-1") wind tunnel model designed and tested by S. C. Johnson in the 2012-2013 timeframe. Three configurations of an all-new model ("Gen-3") were developed to increase the realism of the test
specimen, and included features such as tuned wing modal frequencies, higher-Lock number rotor blades, and blade twist. Most importantly, the Gen-3 models were designed to flutter without the use of an added mass or unconventional center of gravity placement.

Gen-3 was developed through the use of an in-house computer code, which generated damping predictions for the wing modes at various tunnel speeds. Model components and support equipment were fabricated in-house by the author, with some components (e.g. those requiring computer-controlled machining) outsourced to local manufacturers. Wind tunnel tests were performed in the Hammond tunnel from October 2014 through January 2015; these tests showed that the experimentally-measured flutter speeds of the Gen-3 models were within 5-7% of the predicted values, with the Gen-3a (untwisted composite blades) fluttering at approximately 101 ft./sec., and the Gen-3b model (twisted composite blades) fluttering at approximately 97 ft./sec.

The present work has further validated the feasibility of whirl
utter testing at a small scale. The Gen-3 model was able to exhibit whirl flutter without the use of an additional mass, and will permit the testing of devices designed to enhance the whirl flutter margin within the current facility. The techniques used to fabricate the Gen-3 model show potential for introducing features such as blade
flexibility and an modular wing root flexure for a wider test regime.

The objective of the research in this paper was to maximise the amount of perform- ance enhancing aerodynamic down-force generated by the 2005/2006 University of Auckland Formula SAE race car. This was done through a combination of physical modelling using a rolling road wind tunnel research facility and by using computational fluid dynamics. Computational fluid dynamic analysis was used for

Over the last 30 years, Boeing has developed, manufactured, sold, and supported hundreds of billions of dollars worth of commercial airplanes. During this period, it has been absolutely essential that Boeing aerodynamicists have access to tools that accurately predict and confirm vehicle flight characteristics. Thirty years ago, these tools consisted almost entirely of analytic approximation methods, wind tunnel tests, and flight tests. With the development of increasingly powerful computers, numerical simulations of various approximations to the Navier-Stokes equations began supplementing these tools. Collectively, these numerical simulation methods became known as Computational Fluid Dynamics (CFD). This paper describes the chronology and issues related to the acquisition, development, and use of CFD at Boeing Commercial Airplanes in Seattle. In particular, it describes the evolution of CFD from a curiosity to a full partner with established tools in the design of cost-effective and high-performing commercial transports.

In this paper, Thailand county report 2012 on wind engineering is present. First, Development of DPT Standard 1311-50 for wind load and response of buildings is present. The DPT Standard is financially supported by Department of Public Works and Town & Country Planning. The new standard is more accurate than the building code No.6 because it considers the wind speed zoning, surrounding terrain, building shapes, and dynamic properties. Secondly, examples of wind load studies of buildings by TU-AIT wind tunnel test are also presented. Finally, losses due to flood in Thailand in year 2011 are shown.

Recent progress concerning experimental and numerical methods for practical investigations of vehicle soiling are reviewed in this paper. Wind tunnel tests and available measurement techniques are analyzed and compared with respect to their possible applications and to the results they may deliver. Different computational models for liquid films generated by spray impingement on vehicle surfaces are then considered. Models relying either on a dispersed or on a continuous approach are compared, resulting advantages and shortcomings are discussed. It is finally shown that, in spite of considerable progress during the last years, substantial work remains to be done in order to capture the complexity of real film flow dynamics for an accurate representation of wetting processes, film separation and break-up interacting with turbulent flows.

A prediction method is developed for the self-generated noise of an airfoil blade encountering smooth flow. The prediction methods for the individual self-noise mechanisms are semiempirical and are based on previous theoretical studies and data obtained from tests of two- and three-dimensional airfoil blade sections. The self-noise mechanisms are due to specific boundary-layer phenomena, that is, the boundary-layer turbulence passing the trailing edge, separated-boundary-layer and stalled flow over an airfoil, vortex shedding due to laminar boundary layer instabilities, vortex shedding from blunt trailing edges, and the turbulent vortex flow existing near the tip of lifting blades. The predictions are compared successfully with published data from three self-noise studies of different airfoil shapes. An application of the prediction method is reported for a large scale-model helicopter rotor, and the predictions compared well with experimental broadband noise measurements. A computer code of the method is given.

An improved deposition technique for cryogenic hot films used for transition detection in cryogenic tunnels is reported. Tests of the hot films in a low-speed tunnel demonstrated the ability to obtain online transition data. The capability of an enhanced hot film data acquisition system was also demonstrated. A comparison of data from the new system with stability theory shows the detection of Tollmein-Schlicting waves at transition onset.

Hurricane hazard models have become a commonly used tool for assessing hurricane risk. The type of hurricane risk considered varies with the user and can be an economic risk, as in the case of the insurance and banking industries, a wind exceedance risk, a flood risk, etc. The most common uses for hurricane hazard models today include: (i) Simulation of wind speed and direction data for use with wind tunnel test data for the estimation of wind loads vs. return period for design of structural systems and cladding (ii) Estimation of design wind speeds for use in buildings codes and standards (iii) Coastal hazard risk modeling (storm surge elevations and wave heights vs. return period) (iv) Insurance loss estimation (probable maximum losses, average annual losses) This paper presents a brief overview of the history of the modeling process, concentrating on the modeling of the wind, as it is the key input to each of the examples presented above. We discuss improvements in wind field modeling, modeling uncertainties, and possible future directions of the hurricane risk modeling process.

The abrupt wing stall (AWS) program was a 5-year program that addressed the problem of uncommanded, transonic lateral motions, such as wing drop, with experimental, computational, and simulation tools. A brief background is presented as are the motivations and objectives for the AWS program. Since the wing drop discovered in preproduction flight testing for the F/A-18E/F program was the immediate impetus for the AWS project, and since extensive flight data had been gathered, the preproduction F/A-18E configuration was utilized to examine the ability of current computational and wind-tunnel tools to predict such phenomena prior to flight. The scope included both steady and unsteady flow field studies for transonic flight conditions. The AWS program also adapted and assessed a free-to-roll (FTR) wind-tunnel testing technique traditionally used for low-speed studies of lateral dynamic stability for the transonic flow regime. This transonic FTR capability was demonstrated first in a proof-of-concept study and then applied to an investigation of four different aircraft configurations-two that were susceptible to wing drop, the preproduction F/A-18E and the AV-8B, and two that were not, the F/A-18C and the F-16C. Design insights have also been obtained from computational studies of these four aircraft configurations and from computations quantifying the impact of the various geometric wing differences between the F/A-18C

In a major cooperative program within the existing US-German and US-French Memoranda of Understanding/Agreements (MOU/MOA), researchers from German DLR, French ONERA, NASA Langley, and the US Army Aeroflightdynamics Directorate (AFDD) conducted a comprehensive experimental program in October 2001 with a 40% -geometrically and aeroelastically scaled model of a BO-105 main rotor in the open-jet anechoic test section of the German-Dutch

Contemporary high-rise buildings with complex geometric profiles and three-dimensional ͑3D͒ coupled mode shapes often complicate the use of high frequency force balance ͑HFFB͒ technique customarily used in wind tunnel testing for uncoupled buildings. In this study, a comprehensive framework for the coupled building response analysis and the modeling of the associated equivalent static wind loads using the HFFB measurement is presented. This includes modeling of building structural systems whose mass centers at different floors may not be located on a single vertical axis. The building response is separated into the mean, background, and resonant components, which are quantified by modal analysis involving three fundamental modes in two translational and torsional directions. The equivalent static wind load is described in terms of the modal inertial loads. The proposed framework takes into account the cross correlation of wind loads acting in different primary directions and the intermodal coupling of modal responses with closely spaced frequencies. Wind load combination is revisited in the context of modeling of the equivalent static wind loads. A representative tall building with 3D coupled modes and closely spaced frequencies is utilized to demonstrate the proposed framework and to highlight the significance of cross correlation of wind loads and the intermodal coupling of modal responses on the accurate prediction of coupled building response. Additionally, delineation of the proper role of the correlation between integrated loads, modal response, and respective building response components in the evaluation of wind effects on coupled buildings is underscored.

The pressure distributions on upwind sails is discussed and related to the flow field around the headsail and the mast/mainsail. Pressures measured on several horizontal sections of model-scale and full-scale sails are used to provide examples. On the leeward side of the sails, leading edge separation and turbulent reattachment occurs, sometimes followed by trailing edge separation. On the windward side, leading edge separation occurs on the mast/mainsail and, at low angles of attack, it can also occur on the headsail. Differences were found between the leading edge bubbles on the two sails. Pressure trends for different angles of attack are presented, and these can be explained in terms of standard aerodynamic theory, particularly in terms of short and long leading edge separation bubble types. It was found that the pressure distributions measured on mainsails at full- and model-scale showed good agreement on both the windward and leeward sides.

The dynamic derivatives are widely used in linear aerodynamic models in order to determine the flying qualities of an aircraft: the ability to predict them reliably, quickly and sufficiently early in the design process is vital in order to avoid late and costly component redesigns. This paper describes experimental and computational research dealing with the determination of dynamic derivatives carried out within the FP6 European project SimSAC. Numerical and experimental results are compared for two aircraft configurations: a generic civil transport aircraft, wing-fuselage-tail configuration called the DLR-F12 and a generic Transonic CRuiser (TCR), which is a canard configuration. Static and dynamic wind tunnel tests have been carried out for both configurations and are briefly described within this paper. The data generated for both the DLR-F12 and TCR configurations includes force and pressure coefficients obtained during small amplitude pitch, roll and yaw oscillations whilst the data for the TCR configuration also includes large amplitude oscillations, in order to investigate the dynamic effects on nonlinear aerodynamic characteristics. In addition, dynamic derivatives havebeen determined for both configurations with a large panel of tools, from linear aerodynamic (Vortex Lattice Methods) to CFD (unsteady Reynolds-Averaged Navier-Stokes solvers). This work confirms that an increase in fidelity level enables the dynamic derivatives to be calculated more accurately. Linear aerodynamics (VLM) tools are shown to give satisfactory results but are very sensitive to the geometry/mesh input data. Although all the quasi-steady CFD approaches give comparable results (robustness) for steady dynamic derivatives, they do not allow the prediction of unsteady components for the dynamic derivatives (angular derivatives w.r.t. time): this can be done with either a fully unsteady approach (with a time-marching scheme) or with Frequency Domain solvers, both of which provide comparable results for the DLR-F12 test case. As far as the canard configuration is concerned; strong limitations for the linear aerodynamic tools are observed. A key aspect of this work are the acceleration techniques developed for CFD methods, which allow the computational time to be dramatically reduced while providing comparable results.

An overview of the hurricane hazard model, terrain model, wind pressure, and windborne debris models used in the HAZUS-MH hurricane model is presented. These models represent the first three of five major component models used in HAZUS for the prediction of damage and loss to buildings subjected to hurricanes. The five model components are the hurricane hazard model, terrain model, wind load model, physical damage model, and loss model. These models have been validated, wherever possible, through the use of historical data for landfalling hurricanes, wind tunnel test results, field observations of hurricane induced damage and insurance loss data. The HAZUS hurricane model represents an advancement in the state-of-the-art over other hurricane loss prediction models in that it estimates wind induced loads, building response, damage and loss, rather than simply using historical loss data to model loss as a function of wind speed.

= reference length of half-chord b j = breakpoint of the jth segment c 0 , c 1 , c 2 , c 3 , c 4 = coefficients of interpolation polynomial D = generalized damping matrix fV = cubic spline function of flow velocity f i = frequency corresponding to the flow velocity at the ith step g = added structural damping for k method Im = imaginary part of complex number j = sequence number of segment K = generalized stiffness matrix k = reduced frequency k j = the jth reduced frequency in which the generalized aerodynamic matrix is computed M = Mach number M = generalized mass matrix n = number of reduced frequencies for computing aerodynamic influence matrices n a = number of frequency data in a set p = Laplace variable Q s p = rational function approximation for generalized aerodynamic matrix Q 0 j , Q 1 j , Q 2 j = complex-valued coefficient matrices of the jth segment q = vector of generalized coordinates V = flow velocity V i = flow velocity at the ith step = flow density

Helicopter tail shake phenomenon is still remained as a long dragged issue that adversely affected the overall performance, occupants ’ comfortness and handling qualities of helicopter. This problem is more severe in modern helicopter as it needs to fly faster and with high manoeuvrability, causing rigorous interactional aerodynamic (I/A) related vibration problems. The objective of this present research is to improve basic understanding of the viscous unsteady flow phenomenon observed behind the helicopter tail part. A good understanding of this matter is necessary as a typical aspect of tail shake that it has unsteady random character, indicating that the wake induced excitation is in also unsteady of nature. For this, a wind tunnel test had been conducted with a rigid 14 % model of generic Eurocopter 350Z helicopter in the Universiti Teknologi Malaysia – Low Speed Tunnel (UTM-LST) with a test section size of 2m x 1.5m x 5.8m and 288 km/hr maximum test wind speed. The model, suppl...

The unique thermal and mechanical properties exhibited by shape memory alloys (SMAs) present exciting design possibilities in the field of aerospace engineering. When properly trained, SMA wires act as linear actuators by contracting when heated and returning to their original shape when cooled. These SMA wire actuators can be attached to points on the inside of an airfoil, and can be activated to alter the shape of the airfoil. This shape-change can effectively increase the efficiency of a wing in flight at several different flow regimes. To determine the necessary placement of the SMA wire actuators within the wing, a global optimization method that incorporates a coupled structural, thermal, and aerodynamic analysis has been utilized. A genetic algorithm has been chosen as the optimization tool to efficiently converge to a design solution. The genetic algorithm used in this case is a hybrid version with global search and optimization capabilities augmented by the simplex method with selective line search as a local search technique. A cost function based on the aerodynamic properties of the airfoil has been used to optimize this design problem to maximize the lift-to-drag ratio for a reconfigured airfoil shape at subsonic flow conditions. A wind tunnel model reconfigurable wing was fabricated based on the design optimization to verify the predicted structural and aerodynamic response. Wind tunnel tests indicated an increase in lift for a given flow velocity and angle of attack by activating the SMA wire actuators. The pressure data taken during the wind tunnel tests followed the trends expected from the numerical pressure results.

The wind energy market is in full growth in Quebec but technical difficulties due to cold climate conditions have occurred for most of the existing projects. Thus, icing simulations were carried out on a 0.2 m NACA 63 415 blade profile in the refrigerated wind tunnel of the Anti-icing Materials International Laboratory (AMIL). The shapes and masses of the ice deposits were measured, as well as the lift and drag forces of the iced profiles. Scaling was carried out based on the 1.8 MW-Vestas V80 wind turbine technical data, for three different radial positions and two in-fog icing conditions measured at the Murdochville wind farm in the Gaspé Peninsula. For both icing events, the mass of ice accumulated on the blade profile increased with an increase in the radial position. In wet regime testing (first icing event), glaze formed mostly near the leading edge and on the pressure side. It also accumulated by run-off on the trailing edge of the outer half of the blade. In dry-regime testing (second icing event), rime mostly accreted on the leading edge and formed horns. For both icing events, when glaze or rime accreted on the blade profile, lift decreased and drag increased. A load calculation using the blade element theory shows that drag force on the entire blade becomes too large compared to lift, leading to a negative torque and the stop of the wind turbine. Torque reduction is more significant on the outer third of the blade. Setting up a de-icing system only on the outer part of the blade would enable significant decrease of heating energy costs.

CFD analysis of multiple wind towers located on the same building was performed following validation of a benchmark model against wind tunnel data. The positioning of the wind towers was varied in six different cases, two different arrangements with three different spacing lengths between wind towers. All analysis was compared against the benchmark (isolated) wind tower. The ability of the wind towers, particularly the leeward wind tower, to ventilate the space below was determined for a set occupancy against current guidelines for air supply rates. Furthermore, the effect of the spacing and arrangement on CO2 concentration within rooms ventilated by the leeward wind tower was investigated (re-entry of exhaust air pollutants into fresh supply).

It was found that a parallel arrangement of wind towers was not effective for ventilating an occupied volume, regardless of the spacing between the two wind towers when incident wind direction was parallel to the arrangement. The maximum supply rate for the leeward wind tower in parallel arrangement at a spacing of 5 m was just over 50% of the regulation rate (10 L/s/occupant) and 40% of the supply rate of an isolated wind tower. Decreasing the spacing between the parallel wind towers to 3 m further reduces the supply rate to 2.4 L/s/occupant and the device was observed to be operating in reverse (airflow entering from leeward opening). As the angle of wind increased, an improvement of air supply rates was seen. For a staggered arrangement of wind towers, the leeward wind tower was capable of supplying the recommended ventilation rates at all tested spacing lengths.

The average indoor CO2 concentration of the space with the leeward wind tower was higher in the parallel arrangement than the staggered arrangement at 0° wind angle. For the parallel arrangement, the average CO2 concentration was 28–50 ppm higher than the outdoor air. The staggered arrangement effectively minimised the re-entry of pollutants, with the indoor CO2 concentration 1–3 ppm higher than the outdoor.

A new wing-tip concept with morphing upper surface and interchangeable conventional and morphing ailerons was designed, manufactured, bench and wind tunnel tested. The development of this wing tip was done in the frame of an international CRIAQ project, and the purpose was to demonstrate the upper surface morphing and aileron morphing capabilities in improving the wing tip aerodynamic performances. During numerical optimization with ‘in-house’genetic algorithm software, and during wind tunnel experimental tests, it was demonstrated that the air flow laminar state was extended and drag coefficient reduction were obtained.

An experimental investigation was carried out to study the structure of the flow field around three-dimensional obstacles of different aspect ratios, in two different types of boundary layers. The dimensions of the rectangular block obstacles were chosen to represent generic shapes of buildings. In order to study the flow field around a building structure in a wind tunnel test, the simulation of a boundary layer similar to the atmospheric boundary layer was a crucial issue. For the oncoming flow, a boundary-layer profile representing a suburban site was adopted in the present investigation. The studies were performed using different kinds of flow visualisation techniques and a laser Doppler anemometry (LDA) system, specially developed for wind tunnel applications and designed to provide a high spatial resolution. The results of the experiments showed the dependence of the flow structure around the obstacle on its aspect ratio, the angle of attack, the Reynolds number, and the type of boundary layer. Detailed quantitative information of turbulence parameters in the vicinity of the obstacle was attained. In addition, all data were compiled to schematic sketches of the flow topology around three-dimensional obstacles.

The main results of a two-year project aimed at comparing full-scale tests, wind tunnel tests, and numerical analysis predictions are presented. Pressure measurements were obtained from both full-scale tests and wind tunnel tests, in upwind and downwind conditions. The upwind wind tunnel test condition was modelled using a Vortex Lattice code, while the downwind wind tunnel test was modelled using a Navier–Stokes code. The pressures obtained from the three different methods are compared on three horizontal sections of the ...

The wind-induced buckling of thin-walled steel cylinders, such as silos and tanks, was investigated by wind-tunnel testing for a limited range of the parameters. While wind-buckling of short, stocky shells can be well represented by an equivalent uniform external pressure, long shells show quite a different behaviour, which is strongly influenced by the axial compression forces. This paper presents a study of this behaviour, based on numerical analyses and considering various types of imperfection shape. The effect of geometrical nonlinearity, as well as material plasticity, has also been included. A comparison with test results shows good agreement with the numerical results of imperfect shells, provided that special eigenmodeshaped modes of imperfections are excluded.