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Title: Efficiency of plasma actuator ionization in shock wave modification in a rarefied supersonic flow over a flat plate

This paper describes experimental and numerical investigations focused on the shock wave modification, induced by a dc glow discharge, of a Mach 2 flow under rarefied regime. The model under investigation is a flat plate equipped with a plasma actuator composed of two electrodes. The glow discharge is generated by applying a negative potential to the upstream electrode, enabling the creation of a weakly ionized plasma. The natural flow (i.e. without the plasma) exhibits a thick laminar boundary layer and a shock wave with a hyperbolic shape. Images of the flow obtained with an ICCD camera revealed that the plasma discharge induces an increase in the shock wave angle. Thermal effects (volumetric, and at the surface) and plasma effects (ionization, and thermal non-equilibrium) are the most relevant processes explaining the observed modifications. The effect induced by the heating of the flat plate surface is studied experimentally by replacing the upstream electrode by a heating element, and numerically by modifying the thermal boundary condition of the model surface. The results show that for a similar temperature distribution over the plate surface, modifications induced by the heating element are lower than those produced by the plasma. This difference shows that other effectsmore » than purely thermal effects are involved with the plasma actuator. Measurements of the electron density with a Langmuir probe highlight the fact that the ionization degree plays an important role into the modification of the flow. The gas properties, especially the isentropic exponent, are indeed modified by the plasma above the actuator and upstream the flat plate. This leads to a local modification of the flow conditions, inducing an increase in the shock wave angle.« less
Authors:
;  [1] ;  [2]
  1. ICARE, CNRS, UPR 3021, 1C Avenue de la Recherche Scientifique, 45071, Orléans Cedex 2 (France)
  2. IUSTI, Aix Marseille Université / CNRS, UMR 7343, 5 rue Enrico Fermi, Technopôle Château-Gombert, 13453, Marseille Cedex 13 (France)
Publication Date:
OSTI Identifier:
22390547
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1628; Journal Issue: 1; Conference: 29. International Symposium on Rarefied Gas Dynamics, Xi'an (China), 13-18 Jul 2014; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACTUATORS; BOUNDARY CONDITIONS; BOUNDARY LAYERS; EFFICIENCY; ELECTRODES; ELECTRON DENSITY; GLOW DISCHARGES; IONIZATION; ISENTROPIC PROCESSES; LANGMUIR PROBE; MODIFICATIONS; PLASMA; PLATES; SHOCK WAVES; SUPERSONIC FLOW; SURFACES; TEMPERATURE DEPENDENCE; TEMPERATURE DISTRIBUTION