Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 23 for “"Aerofoils"”.
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Experimental investigation of low aspect ratio aerofoils.
Thesis: M.S., Massachusetts Institute of Technology, Department of Ocean Engineering, 1972
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Lift fluctuations on aerofoils in transverse and steamwise gusts.
A program of research is described which investigated the aerodynamic reponse of an isolated aerofoil to an unsteady field of flow, The effects df both 'transverse gusts' as considered by Karman and Sears (13) and 1 streamwise gusts' as considered by Horlock (4 0), have been studied. To enable …
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Nonlinear wake evolution of Joukowski aerofoils in severe maneuver
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1989.
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Asymptotic approximations for the sound generated by aerofoils in unsteady subsonic flows
… by unsteady perturbations interacting with solid aerofoils in background steady flows, in an attempt to further develop analytic models for the noise generated by blades within turboengines. Specifically, high-frequency unsteady gust and sound wave perturbations are considered and asymptotic …
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Aeroacoustic transfer of leading edge serrations from single aerofoils to low-pressure fan applications
… noise reduction mechanisms for the single aerofoils are transferable to the rotating domain. On the other hand, additional aerodynamic mechanisms are found to dominate the noise reduction for the instability region of the fan, also contributing to reduced blade-to-blade interaction effects. …
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An analysis method for the viscous/inviscid flow around two dimensional multi-element aerofoils including surface roughness effects
… steady flow around two dimensional multi-element aerofoils having a rough or smooth surface.The potential flow over the aerofoil is solved by replacing the aerofoil contour with a polygon of plane panels and using linear distributed vorticity on the panels to represent the aerofoil. Boundary layer …
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Aerodynamic Response of a Two-Dimensional Cambered Wing at Low Reynolds Numbers in Steady-State Onset Turbulence
… the potential for predicting these effects, the aerofoils were tested under equivalent sinusoidal-pitching conditions. It was determined that turbulence has a significant effect on the performance of low Reynolds number aerofoils, and this response is also influenced by camber. The cambered …
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The Performance of Aerofoil Cascades Using Circulation Control
… of a cascade of two-dimensional, bluff aerofoils employing circulation control by a tangential blowing jet is investigated. Expressions for the lift and drag of such a cascade are derived to eliminate the direct effect of the blowing jet on the measured performance. The cascade …
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Computation of high-lift aerodynamics using unstructured grids and Reynolds-stress turbulence models
… the U.K. National High-Lift Programme. The aerofoils considered include a3, 4 and 5-element configuration, designated NHLP L1/T2, NHLP L1/T7 andNHLP L1/T8 respectively.The results for the L1/T2 and L1/T7 aerofoils show only marginal differenceson the predicted aerodynamic loads. The results …
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Analysis and reconstruction of dynamic-stall data from nominally two-dimensional aerofoil tests in two different wind tunnels
… 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 …
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Scattering by porous aerofoil adaptations
… noise from the leading and trailing edges of aerofoils, as well as contributing to turbo-machinery noise through fan blades and guide vanes. The study of owl flight has led to numerous bio-inspired adaptations designed to reduce aerodynamic noise passively. Firstly, through material changes: …
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Active Suppression ofAerofoil Flutter via Neural-Network-Based Adaptive Nonlinear Optimal Control
… deals with active flutter suppression (AFS) on aerofoils via adaptive nonlinear optimal control using neural networks (NNs). Aeroelastic flutter can damage aerofoils if not properly controlled. AFS not only ensures flutter-free flight but also enables the use of aerodynamically more efficient …
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Fast prediction of transonic aeroelasticity using computational fluid dynamics
… oscillations predictions. Results are shown for aerofoils, and the AGARD, Goland, and a supercritical transport wing. It is shown that the methods presented allow results comparable to the full order system predictions to be obtained with CPU time reductions of between one and three orders of …
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Generation of discrete frequency tones by the flow around an aerofoil
… discrete frequency noise generated by aerofoils, is investigated. It is heard from an aerofoil placed in streams at low Mach number flows when inclined at a small angle to the stream. The tones are heard as a piercing whistle, commonly up to 30 dB above the background noise level. The …
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Is the Weis-Fogh principle exploitable in turbomachines?
… to show that strong blade interactions can cause aerofoils to work usefully at higher mean loadings than those in conventional designs, and that the increased loading is also associated with an improved aerodynamic efficiency. Our analysis seems to predict the experimental performance very …
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Extracting energy from unsteady flows through vortex control
… of the classical linear theory for unsteady aerofoils. It combines the effects of nonuniform inflow and foil motion to predict the resulting thrust, lift, and moment. The numerical procedure allows for nonlinear interaction between the foil, performing large amplitude oscillations, and the …
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Implementation of two-dimensional time accurate flow simulation on moving mesh exploiting mesh rupturing
A two-dimensional dynamic moving mesh algorithm is implemented for simulating aerodynamic oscillating airfoils. The airfoil is inserted into a uniform unstructured background mesh by exploiting an new technique named mesh rupturing, which allows for significant geometry movement without grid …
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Control design and energy optimisation of a buoyant airborne wind turbine
… by using a combination of tethers and bespoke aerofoils. In contrast to conventional horizontal axis wind turbines (HAWT), the tower is replaced with lightweight tethers resulting in a reduction in both the overall mass, and more importantly cost of the system. Currently, there is significant …
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The prediction of unsteady three-dimensional aerodynamics on wind turbine blades
… more appropriate link to dynamic stall for some aerofoils. Finally, the phenomenon of tower shadow on a downwind turbine is studied. Unaveraged pressure measurements and integrated normal force coefficients from tests conducted at Glasgow University are analysed. The analysis highlights many …
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