Magnetohydrodynamic Aerobraking Shock Stand-Off Measurements with Flight Representative Electrodynamic Boundary Conditions

Abstract

This paper reports on an experimental study of magnetohydrodynamic aerobraking using an expansion tube facility, which can generate the correct electrodynamic boundary conditions for spacecraft atmospheric entry. Argon test gas was selected for its relatively simple chemistry, making it well suited to develop experimental test cases for numerical code development. Test models were constructed from either spherical neodymium permanent magnets or steel balls. Ceramic paint was used as an electrically insulating surface boundary condition for experiments where this was required. Finite-rate reacting computational fluid dynamics of the experimental configuration indicates that relatively long duration argon relaxation times lead to a highly nonequilibrium shock layer in which a significant Hall effect arises. This is important because it is expected that future flight vehicles using magnetohydrodynamic aerobraking technology will also be operated at flight conditions where Hall effect is strong. Shock stand-off was measured using high-speed luminosity imaging for various magnetic and nonmagnetic model configurations. Experimental results in this paper support previous numerical studies that found that only an electrically insulated model surface can generate a significant magnetohydrodynamic interaction when Hall effect is strong.