Carlo Angelo Borghi

Electrohydrodynamic interaction induced by a dielectric barrier discharge

In the present work an experimental investigation on the electrohydrodynamic (EHD) interaction effect, induced by means of a dielectric barrier discharge on a 1atm subsonic air flow, is described. The air flow is obtained in an open circuit blowing wind tunnel at different air speeds. A plane plasma panel equipped with a dielectric discharge barrier system is immersed in the flow. A single phase sinusoidal power supply system, a superposition of a single phase sinusoidal system with a dc voltage supply, and a three phase symmetrical power supply configuration are considered. Electric, fluid dynamic, and spectroscopic diagnostic techniques are utilized. Pitot probe measurements are performed in the boundary layer on the plasma panel surface. Schlieren imaging is done to visualize the plasma sheath. Vibrational and rotational temperatures are evaluated by means of spectroscopic techniques. The force induced on the flow by the dielectric barrier discharge acts on the ions of the non-neutral sheath ahead of t...

Hypersonic MHD Interaction on a Conical Test Body With a Hall Electrical Connection

The MHD interaction around a conical test body in a hypersonic argon flow was experimentally investigated. The aim of the experiment was to produce a database to be used for the validation of numerical codes for the analysis and simulation of the magnetofluid dynamics in hypersonic flows. In these experiments, the flow was obtained in the High-Enthalpy Arc-heated hypersonic wind Tunnel of Alta, Pisa, Italy. Speeds at Mach 6 were reached. In this experiment, the flow and plasma characteristics have been determined. The MHD interaction was obtained in the shock layer of a conical test body placed at the exit of the hypersonic nozzle. The realized electrical configuration allowed the enhancement of the effect of the MHD interaction on the plasma parameters. This was done by utilizing the Hall field to generate the MHD interaction and by short-circuiting the Faraday current inside the plasma of the shock layer. The magnetic-flux density was produced by an array of three magnets located in the test body. Test runs were performed at three different stagnation pressures. Fluid-dynamic, electrical, and optical observations have been done. The experiment showed a large effect of the MHD interaction on the values of the measured quantities. In order to have a test body that is entirely contained in the region where a uniform hypersonic flow has been measured, a test body of smaller size has been constructed and tested. The results obtained in this case confirm the results of the tests with the larger body.

Analysis of Magnetoplasmadynamic Interaction in the Boundary Layer of a Hypersonic Vehicle

A model for the analysis of the magnetoplasmadynamic regime, devoted to magnetohydrodynamic (MHD) systems in a hypersonic flight, is presented. In the assumption of a low-magnetic-Reynolds-number regime, the model couplesa time-dependent formulation of fluid dynamics with steady-state electrodynamics. The Navier-Stokes equations are discretized by means of a finite volume formulation. The electrodynamics is discretized by means of a finite element method. The model has been utilized for the analysis of the MHD interaction in the boundary layer of a test body in a wind tunnel. The activity is aimed to design the experimental activity in the frame of an Italian Space Agency research project on the MHD interaction in hypersonic flows. Calculations have shown that MHD interaction can be greatly weakened by the effect of the Hall current.

Modeling Laser-Induced Plasma Expansion Under Equilibrium Conditions

In this work we present a theoretical study concerning the Laser Induced Plasma (LIP) produced by the interaction between a nanosecond laser with a metallic titanium target in air and in water. The strong influence of chemical processes on the fluid dynamic expansion has been investigated. To this aim a 2D fluid dynamic code has been developed and coupled with a chemical equilibrium model.

Plasma and Flow Characterization in a Flat Panel One Atmosphere Uniform Barrier Discharge

The properties of a one atmosphere uniform barrier discharge panel in a subsonic wind tunnel, have been investigate. Electric, fluid-dynamic and spectroscopic diagnostic techniques have been utilized. The discharge panel was tested inside an open circuit blowing wind tunnel, at different power supply conditions and air speeds. The characteristic of the boundary layer on the plasma panel, have been investigated by means of a Pitot probe. Vibrational and rotational temperatures have been evaluated by means of spectroscopic techniques. The measured electric properties were correlated to spectroscopic data. Flow visualization was also performed by means of a Schlieren setup. In order to raise the thrust efficiency, the set up of the plasma panel has been varied. For each electrode pair, a high voltage DC electrode was added. This leads to a DC discharge on the plasma sustained by the AC barrier discharge. This discharge causes an aerodynamic effect originated by the associated ionic wind.

MHD Interaction over an Axial Symmetric Body in a Hypersonic Flow

The MHD interaction around a conical test body in a hypersonic argon flow is experimentally investigated. The hypersonic flow is realized in the high-enthalpy arc-heated wind tunnel of Alta (Pisa-Italy) at Mach 6. The aim of the experiment is to produce a data base to be used for the validation of numerical codes which are utilized to analyze the magneto-fluid dynamics in hypersonic flows. In the present experiment the MHD interaction is obtained in the shock layer of a conical test body placed at the exit of the hypersonic nozzle. The electrical configuration realized, allows to enhance the effect of the MHD interaction on the plasma parameters. This is done by utilizing the Hall field to generate the MHD interaction and by short-circuiting the Faraday current inside the plasma of the shock layer. The magnetic flux density is produced by an array of three magnets located in the test body. Test runs are performed at three different stagnation pressures. Fluid-dynamic, electrical and optical observations have been done. The experiment showed a large effect of the MHD interaction on the values of the measured quantities.

Numerical solution of the nonlinear electrodynamics in MHD regimes with magnetic Reynolds number near one

In magnetohydrodynamic (MHD) regimes of plasmas with magnetic Reynolds number comparable to one, electrodynamics exhibits a nonlinear characteristic. In the present paper, the electrodynamics has been discretized utilizing a finite-element method. The problem unknown is the electric scalar potential. Nonlinearity is caused by the dependence of the electric transport parameters and of the source terms on the magnetic flux density. Different approaches are evaluated to deal with the nonlinearity. The model has been coupled with a solver of the Navier-Stokes equations. The MHD interaction in the boundary layer of an hypersonic flight has been analyzed.

An application of the inexact Newton method to nonlinear magnetostatics

Inexact Newton solvers offer many attractive features for the solution of nonlinear problems in the field of electromagnetics. A critical point for the optimal setup of the solver is the choice of the best algorithm for the evaluation of the approximate solution of the linear systems at each Newton step and the most effective preconditioning strategy. In this paper, the Newton iterative solver method is proposed for the solution of a nonlinear magnetostatic problem. The problem is discretized by means of a finite-element approach. The generalized minimum residuals (GMRES) method is adopted as linear solver, and three preconditioners are tested. The performance of this procedure is evaluated for different magnetostatic problems and compared to the results obtained by means of a Newton-Raphson method.

Numerical Analysis of the Experimental Results of the MHD Interaction around a Sharp Cone

3In this paper is presented a numerical investigation on the results of a recent experiment on the MHD interaction. The experiments has been carried out on a sharp cone in an ionized argon flow. The investigation is performed utilizing a numerical code based on low magnetic Reynolds number approximation. A sensitivity analysis is performed on the impact of the electric transport properties of the plasma. The effect of the Hall current density on the efficience of the MHD interaction are analyzed as well.