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Magnetofluidodinamica
Applicata
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Numerical analysis of dielectric barrier discharge
Fabio Roveda
- Ciclo XXIV - 2012
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Abstract -
Il lavoro di Dottorato descritto nella tesi "Numerical analysis of dielectric barrier discharge" è incentrato sulla simulazione della scarica a barriera sviluppata da attuatori al plasma, per applicazioni aeronautiche. Tali dispositivi permettono di realizzare una scarica superficiale in regime di non equilibrio a pressione atmosferica, rendendo disponibili specie altamente reattive in un gas globalmente freddo. Questa caratteristica rende il fenomeno della scarica a barriera particolarmente interessante per diverse applicazioni ingegneristiche ed il contesto applicativo all'origine del presente lavoro riguarda il controllo delle proprietà fluidodinamiche nello strato limite al di sopra di un profilo aerodinamico.
Un modello fisico è stato sviluppato ed implementato al calcolatore per simulare la scarica e studi particolari sono stati condotti per valutare l'effetto di diverse condizioni operative sulle proprietà elettriche e cinetiche. I risultati riguardanti la sola parte di cinetica del plasma sono stati elaborati per studiare numericamente l'interazione scarica-fluido e i risultati denotano alcune criticità nella simulazione della forza elettrodinamica generata dalla DBD.
La successiva fase di ricerca ha riguardato lo studio inverso del campo di forza tale da produrre i regimi fluidodinamici misurati e riportati in letteratura: questo lavoro ha confermato che il codice di simulazione fluidodinamica è in grado di approssimare in modo realistico il campo di velocità indotto dall'interazione EHD.
Infine, si è validato numericamente un metodo diagnostico non invasivo basato su immagini Schlieren per studiare il campo di velocità prodotto dalla scarica a barriera.
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Numerical strategies for the solution of the
magneto-fluid-dynamic problem at Low Magnetic Reynolds Numbers
Chiara Latini
- Ciclo XXIII - 2011
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Abstract -
The work presented in this thesis is focused on a numerical analysis of the shock moving effect. In the re-entry phase,
for Mach numbers ranging from 12 to 25, the temperature at the vehicle surface can exceed 2000 K, due to both convection and radiation from the shock layer. In order to face with
the strong thermal stresses the fuselage is subjected to, the body walls are equipped with a shielding coverage made up of different materials ensuring a proper heat dissipation.
By pushing the shock front away from the body nose, the heat fluxes are mitigated and the load on the thermal shield is reduced. If a magnet system is installed on the fuselage,
capable to generate fields at the order of Tesla, a Lorentz force acts on the charges convected with the ionized air surrounding the aircraft, and generates an electromotive force.
The resulting current J couples with magnetic field generating a body force J x B acting on the flow. Several magnets configuration have been proposed and tested in wind tunnels
facilities. The modeling effort presented here concentrates on a axi-symmetric configuration for the magnets that generates a current flow in the azimuthal direction, positioned
where the MHD interaction is stronger, that is, where the flow field is almost orthogonal to the magnetic flux density.
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Diagnostic Techniques for MHD in Hypersonic Flows
Veronica
Maria Granciu - Ciclo XXII - 2010
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Abstract -
The MHD interaction in a hypersonic flow had been experimentally investigated. A conical test body had been placed at the exit of the hypersonic nozzle. An ionized Argon flow at a Mach 15 and air flow at Mach 9 had been obtained. Numerical simulations realized by means of a time dependent two dimensional code at low magnetic Reynolds numbers showed a good agreement with the measurements. The important role of the Hall parameter in the hypersonic MHD interaction process had been
demonstrated.
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Diagnostic
techniques for EHD and MHD interaction
Gabriele Neretti
- Ciclo XXI - 2009
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Abstract - The
impact of plasma technologies is growing both in the academic and in
the industrial fields. Nowadays, a great interest is focused in
plasma applications in aeronautics and astronautics domains. Plasma
actuators based on the Magneto-Hydro-Dynamic (MHD) and
Electro-Hydro-Dynamic (EHD) interactions are potentially able to
suitably modify the fluid-dynamics characteristics around a flying
body without utilizing moving parts. This could lead to the control
of an aircraft with negligible response time, more reliability and
improvements of the performance. In order to study the
aforementioned interactions, a series of experiments and a wide
number of diagnostic techniques have been utilized.This thesis is
split in three parts. In the first one the basic theory of the
utilized diagnostic techniques is described. In the other two parts,
the application of these diagnostics to EHD and MHD experiments are
presented. The common basis of this work has to be searched in the
study and in the measurement methods of the weakly ionized gases
which characterize the EHD and MHD interaction processes.
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Diagnostic
techniques for MHD interacting plasmas
Mario Roberto
Carraro - Ciclo XVII - 2005
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Abstract - Plasmas
are nowadays widely applied in the research domain and in industrial
exploitation. Since plasma parameters are quantities that can be
easily influenced by the measurement set-up, particular attention
should be paid in the plasma experiment phase, during the
development and application of the diagnostic techniques. As regards
the diagnostic techniques, two different classes can be
distinguished: passive and active. In the former case, the radiation
from the plasma is studied. From the technical point of view it is a
relatively simple application even if the phase of the result
interpretation can be relatively complicated. In the latter case, an
interaction with the plasma takes place. For example, a microwave
beam can be directed to the plasma. This can offer much more
information about the plasma itself, but is both more demanding on
the experimental setup and can interfere with the object of study.
The main aim of this thesis was the development of different plasma
diagnostic techniques, both active and passive. Those techniques
were applied in different plasmas. Even if this work is split in two
parts, each referring to a different experiment, the common basis
still exists and has to be searched in the study and in the
integration of those plasma measurements methods.
Thesis_PhD_Carraro_Index.pdf
Thesis_PhD_Carraro_Part1.pdf
Thesis_PhD_Carraro_Part2.pdf
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