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 26 for “"Vortex interactions"”.
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Unsteady pressure and vorticity fields in blade-vortex interactions
The unsteady interaction of a vortex core with a NACA 0015 airfoil is studied in two dimensions. A two-component, three-beam Helium-Neon laser-Doppler Velocimetry system is used to take data in a water tunnel. Ensemble-averaged velocity fields are obtained in the region of the leading edge of the …
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Modification of Blade-Vortex Interactions Using Leading Edge Blowing
… both the structural and acoustic senses. These interactions are ubiquitous in nature and engineering. A flow control technique is sought to mitigate this interaction, thereby decreasing the level of structural vibration. This thesis investigates the effectiveness of steady leading-edge blowing …
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Fuel-vortex interactions for enhanced mixing in supersonic flow
… jets arranged to produce multiplicative fuel-vortex interactions for mixing enhancement in a supersonic main flow. The physical ramp injector was a previously optimized and tested swept-ramp design. Test conditions included a Mach 2.0 freest ream of air with a Reynolds number of 3.63 x 10⁷ per …
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An Experimental Investigation of Two-Dimensional Flame-Vortex Interactions (Acoustics Addition Rate)
… the interaction between a flame and a single vortex impulsively generated by the flame. The objectives are to investigate the amplitude of the cylindrically diverging acoustic wave produced by the interaction and to develop a quantitative approach to determine the degree of violence of the …
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ERROR BOUNDS OF COMPACT FINITE DIFFERENCE METHODS FOR SOME DISPERSIVE PDEs AND APPLICATIONS
… initial data in simulations of quantized vortex interactions under the two-dimensional nonlinear Schrödinger equation with periodic boundary conditions.
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An output-based adaptive and high-order method for a rotor in hover
… simulation of rotorcraft wakes and blade-vortex interactions continues to be a challenge, the output-based adaptation scheme is used with thrust as the output of interest to refine the mesh. The result is a solution with less than three million degrees of freedom that is capable of …
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Imaging vortex dynamics in Josephson arrays using magnetic force microscopy
Vortices and vortex lattices play a major role in determining the transport properties of type-II superconductors[1–3], and enable a platform to investigate exotic superconducting physics[4,5]. The study of vortex matter has generally focused on novel states in 2D films and structures, and has …
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Vortex distributions and dynamics in superconductors near surface steps and sample edges studied by scanning SQUID microscopy and critical current measurements
We have studied the interactions of vortices in superconductors with surface features and sample edges. Surface steps can generate an asymmetric vortex pinning potential and can influence the distribution of vortices upon cooling into the superconducting state in an applied magnetic field. The edge …
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Vortex driven flame dynamics and combustion instability
… elementary processes are acoustic wave-flame interactions, flame-vortex interactions, equivalence ratio fluctuations, flame-wall interactions and the unsteady stretch rate. To investigate the flame- vortex interaction mechanism, a parametric study is performed in single and double expansion …
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The Development and Applications of a Numerical Method for Compressible Vorticity Confinement in Vortex-Dominant Flows
… real engineering problems involving complex vortex structures and assessing the accuracy by comparison with existing experimental data and with other computational techniques. Examples considered include supersonic conical flows over delta wings, shock-bubble and shock-vortex interactions, …
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Physics-based flame dynamics modeling and thermoacoustic instability mitigation
… the dynamics are primarily governed by the flame-vortex interactions, whereas the equivalence ratio oscillations have minor impacts. Depending on the equivalence ratio, inlet temperature and the fuel composition, the combustor operates under different dynamic modes. The operating conditions at the …
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The Interaction of a Transient Forward Axial Disturbance Flow With a Rotor
… captures the complex aerodynamic and acoustic interactions inherent in rotor operations. Validation of the numerical framework was achieved through comprehensive comparisons with available experimental data, demonstrating a high level of accuracy in predicting both aerodynamic performance …
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Active combustion control : modeling, design and implementation
… concerns the modeling of hydrodynamics and its interactions with the other components that contribute to combustion dynamics. The second is the impact of active control on emissions even while suppressing the pressure instability. The third is the evaluation of model-based active controllers in …
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Parallel pulsed jets for precise underwater propulsion
… In this thesis, I experimentally investigate how interactions between neighboring jets in a multi-jet thruster will affect the system's propulsive performance. I use high-speed fluorescence imaging to investigate the mutual influence of two pulsed jets under conditions relevant to low-speed …
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High order numerical methods applied to the analysis of transport phenomena in combustion
… diffusion flame perturbed by a laminar vortex ring is investigated. The local extinction of the flame leads to the apparition of flame-edges separating the burning and extinguished regions of the perturbed mixing layer. The dynamics of these edges is modelled using previous numerical …
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Interacting non-Abelian anyons in an exactly solvable lattice model
… can acquire finite energy due to short range vortex-vortex interactions. By studying the spectral evolution as a function of the vortex seperation, we unambigously identify the zero modes with the fusion degrees of freedom of non-Abelian anyons. To calculate the non-Abelian statistics, we show …
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Vortex Configurations Of Bosons In Rotating Optical Lattices
… on sites. We discuss connections between these vortex structures and the Hofstadter-butterfly spectrum of free particles on a rotating lattice. We then investigate vortex configurations within a harmonically trapped Bose-Einstein condensate in a rotating optical lattice. We find that proximity …
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The effects of disorder on superconducting islands and island arrays
… including localization, Cooper pairing and interactions are at play. These strong interactions have been known to lead to unusual ground states and previously theoretically prohibited metallic states. However, despite various excellent theoretical and experimental efforts, the origin of …
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Predicting the high-frequency airloads and acoustics associated with blade-vortex interaction
As a rotorcraft descends or manoeuvres, the interactions which occur between the rotor blades and vortical structures within the rotor wake produce highly impulsive loads on the blades and with these a highly intrusive external noise. Brown’s Vorticity Transport Model has been used to investigate …
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Magnetic force microscopy studies of mesoscopic superconducting structures
… force microscopy (Φ0-MFM) for investigating vortex and fluxoid sates in mesoscopic superconducting (SC) structures. The technique relies on the magneto-mechanical coupling of a MFM cantilever to the motion of fluxons. The novelty of the technique is that a magnetic particle attached to the …
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