Plasma methods for propulsion

Authors:

  • Mose Akyuz
  • Magnus Bergh
  • Tomas Hurtig

Publish date: 2013-04-09

Report number: FOI-R--3610--SE

Pages: 36

Written in: English

Keywords:

  • plasma assisted combustion
  • molecular dynamics
  • combustion
  • combustion
  • kinetics
  • plasma actuator
  • surface discharge
  • boundary layer control
  • capacitive
  • discharge

Abstract

Two different aspects of plasma technology for propulsion are treated in this report, plasma assisted combustion (PAC) and surface discharges (plasma actuators) for boundary layer control. In plasma assisted combustion a non-thermal plasma is generated in or in close vicinity of the flame in order to increase the number of radicals and excited atoms and molecules. The excited states and radicals increase the chemical reaction rates in the combustion and provide a way of controlling or assisting the combustion. An outstanding problem in the field of theoretical research on PAC is modeling of the modification of the reaction pathways that occur when the combustion is 'seeded' with radicals and excited states. I.e. how can we describe the chemical kinetics under the influence of a non-thermal plasma background? In this report a method for finding kinetic mechanisms using a molecular dynamic (MD) simulation method is briefly studied. These models (MD) are typically developed for modeling of solid and/or liquid states of matter. A conclusion from this study is that due to the low density of the material (gas), in for example a gas turbine, the computational time may become too long. Plasma actuators are surface discharges that transfer momentum from the ionized species (mostly negatively charged oxygen molecules) to the surrounding air in a thin layer close to the surface of an airplane wing or hull. Compared to other, often mechanical, methods for boundary layer control, the plasma actuator offers the possibility for high speed actuation, thus enabling its use in fast feedback systems. However, the plasma actuator also presents a few problems, one is the fact that the actuator represents a difficult load in terms of electrical impedance matching. In order to construct and optimize a power supply to drive a plasma actuator a simple circuit model of an actuator is needed. In this report one such model is presented in detail and the results are compared with experimental data.