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 17 of 17 for “"laminar separation bubble"”.
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Low Reynolds Number Laminar Separation Bubble Control Using a Backward Facing Step
<p>The problem of a laminar separation bubble on the upper surface of a 9.5% thick airfoil operated at low Reynolds number (R<sub>N</sub> = 380,000) was investigated experimentally.</p> <p>An unmodified LRN-010 airfoil and a modified LRN-010 airfoil with a backward facing step on its upper surface …
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The development of kinetic models and simulation methods to study molecular fluctuations, modal response, shock-laminar separation bubble instabilities
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-11-11 without embargo terms
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The effect of free stream disturbances and control surface deflections on the performance of the Wortmann airfoil at low Reynolds numbers
… data, and flow-visualization studies. The laminar separation bubble which frequently occurs on the upper surface of the wing is found to dominate its performance and gives rise to a hysteresis loop for lift and drag. Changes in airfoil performance due to positive flap or control surface …
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Aspect ratio effects on wings at low Reynolds numbers
… wingtips have a rather restricted effect on the laminar separation bubble. The disappearance of the bubble extends only for a small distance inboard from the tips. The size of the hysteresis loop and the Reynolds number at which hysteresis starts was found to be influenced by the aspect ratio. …
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Effects of Free Stream Turbulence on Compressor Cascade Performance
… cascade angles where transition exists within a laminar separation bubble, increasing free-stream turbulence suppressed the extent of the laminar separation bubble and led to an earlier turbulent reattachment.
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Unsteady flow physics of airfoil dynamic stall
… dynamic stall process. A spatially-contracting laminar separation bubble was also identified near the airfoil leading edge from the characteristic pressure plateau in the surface pressure distribution. The dominant frequencies associated with the laminar separation bubble were extracted using a …
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The hemisphere-cylinder at an angle of attack
… were focused mainly on the development of the laminar separation bubble as a function of angle of attack, the conditions under which open and closed separation exist and the interaction between the separation bubble and the leeward vortices. A digital processing method was developed to convert …
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High-order implicit large-eddy simulation for transitional aerodynamics flows
… for natural transition to turbulence through a laminar separation bubble. In short, this thesis aims to demonstrate the potential of high-order ILES for simulating transitional aerodynamic flows. This will be illustrated through numerical results and supported by theoretical considerations.
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Aerodynamic and Acoustic Modeling for eVTOL Rotor Noise Prediction
… low-Reynolds-number flow physics, including laminar-turbulent transition and laminar separation bubble behavior.</p> <p>Predicted acoustic spectra were validated against experimental measurements obtained in the Virginia Tech Stability Wind Tunnel. Results demonstrate that turbulence model …
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Aerodynamic characterization of a Griffith-type transonic, laminar-flow airfoil
… airfoil to evaluate the effectiveness of its laminar flow qualities and boundary-layer flow-control characteristics in the transonic regime. Airfoil surface and wake pressure data were acquired to characterize the aerodynamic performance across a range of α = -2˚ to 2˚ and M = 0.3 to 0.7. In …
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Numerical studies of the flow around an airfoil at low Reynolds number
… and linear stability analysis. The behaviour of laminar separation bubbles formed on a NACA-0012 airfoil at Rec = 5 £ 104 and incidence 5± is investigated. Initially volume forcing is introduced in order to promote transition to turbulence. After obtaining sufficient data from this forced case, …
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Aerodynamic and Electromechanical Design, Modeling and Implementation Of Piezocomposite Airfoils
… modes are identified that result in the delay of laminar separation bubble and improvement of lift. Periodic excitation to the flow near the leading edge of the airfoil is used as the flow control method. The effects of amplitude, frequency and spanwise distribution of excitation are determined …
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Unsteady modes in the flowfield about an airfoil with a leading-edge horn-ice shape
… reattachment location of the ice-induced laminar separation bubble downstream of the horn-ice shape using the surface hot-film array measurements. The maximum amount of unsteadiness in the iced-airfoil flowfield was observed to increase with increasing angle of attack. For a fixed angle of …
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Shift - flap : Shear-layer instabilities and flow transition – A fundamental link to airfoil performance
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo terms
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Unsteady separation control on wind turbine blades
… and sustained yaw misalignment. The unsteady separation due to dynamic stall can lead to excessive loads, much larger than the design loads for the turbine, and vibrations in the blade, leading to fatigue damage. Furthermore, massive flow separations can lead to performance losses for the …
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Bio-Inspired Axial Fan Design, 3D Printing Fabrication and Characterization for Noise and Flow Performance Optimization
… beamforming measurements, reveal the role of laminar separation bubbles and trip location in controlling boundary-layer development and acoustic scattering. Finally, the developed noise-control strategies are integrated at the system level, where their combined effects on rotor aerodynamic and …
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Experimental wind tunnel study of airfoils with large flap deflections at low Reynolds numbers
Lift, drag, and moment measurements were taken at low Reynolds numbers for four airfoils with trailing edge plain flaps in an attempt to understand the effects of Reynolds number, percent thickness (t/c), percent chord of flap (flap-chord ratio), and flap deflection on airfoil performance. The four …