MHD acceleration of supersonic air flows using electron beam-enhanced conductivity Conference Paper uri icon

abstract

  • 1998 by S.O.Macheret. Published by the American Institute of Aeronautics and Astronautics, Inc. Recently, the authors suggested a new concept for long run time hypersonic wind tunnel. The concept includes an ultrahigh-pressure driver, laser, microwave, or particle-beam energy addition to dense supersonic stream, and an MHD accelerator. The optimal conditions for the MHD channel entrance were determined as pressurep0.1 atm, temperature 7300-1500 K, with hypersonic flow velocity impacted due to the beamed enthalpy addition upstream of the MHD channel. For an MHD channel to provide a significant flow enthalpy change over a reasonable length, electric conductivity must be high enough, requiring an external ionizer, such as an electron beam. In the present paper, we describe initial steps in developing a comprehensive model of the hypersonic MHD channel with electron beam as an ionizer. First, a quasi-one-dimensional model of electron beam propagation along strong magnetic field (across the channel) is developed. The model is based on the recently developed "forward-backward" approximation, and it incorporates major inelastic collision processes. The model predicts non-uniform ionization rates across the channel, and helps to design optimum configurations, such as several opposing beams, to make ionization profile more uniform. The electron beam propagation model is then coupled with a set of two-dimensional viscous gas dynamic equations, producing a relatively simple 2D model. The model incorporates magnetohydrodynamic effects and non-uniform ionization profiles. In the present first-approximation form, the model disregards turbulence, flow separation, instabilities, and detailed chemical, vibrational, and ionizational kinetics. Sample calculations using the newly developed code are encouraging in that they yield reasonable 2D profiles of flow properties. The paper also discusses some boundary layer effects. Thermal ionization in hypersonic boundary layers is shown to be a potential source of short-circuiting which could limit the maximum flow velocity. On the other hand, strong magnetic field could be a factor preventing the breakdown through the boundary layer.

name of conference

  • 29th AIAA, Plasmadynamics and Lasers Conference

published proceedings

  • 29th AIAA, Plasmadynamics and Lasers Conference

author list (cited authors)

  • Macheret, S., Shneider, M., Miles, R., Lipinski, R., & Nelson, G.

publication date

  • January 1, 1998 11:11 AM