This paper reports on an experimental study of magnetohydrodynamic aerobraking for Mars entry at velocities ranging from 7.4 km · s−1 to 13.5 km · s−1, performed in the X2 expansion tube. High-speed images were recorded of the shock layer around a 1:26 scaled test model based on NASA’s Mars Science Laboratory entry vehicle. Both baseline and magnetic cases were considered, where the magnetic field was provided by a 76 mm diameter, N52-Neodymium permanent magnet with stagnation point magnetic flux density measured as 0.41 T. Thicker forebodies were also considered in order to provide more data points, with measured stagnation point magnetic flux density of 0.29 T. The results showed a significant increase in shock standoff of up to 259% for the 13.5 km · s−1 condition. The ratio of magnetic to non-magnetic shock standoff scaled and increased linearly with the value of the MHD interaction parameter, which partially contradicts analytical predictions from past studies that predicted a power law increase. At 7.4 km · s−1 no increase in shock standoff was observed, however, despite the significant MHD interaction parameter. This could be due to Hall effects although numerical studies should be performed and take into account MHD interaction including Hall effects, in order to better understand the underlying phenomenon occurring in the shock layer.

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Experimental Investigation of Magnetohydrodynamic Aerobraking for High Velocity Mars Entry

  • A. Lefevre,
  • D. E. Gildfind,
  • M. Uren,
  • Y. Liu

摘要

This paper reports on an experimental study of magnetohydrodynamic aerobraking for Mars entry at velocities ranging from 7.4 km · s−1 to 13.5 km · s−1, performed in the X2 expansion tube. High-speed images were recorded of the shock layer around a 1:26 scaled test model based on NASA’s Mars Science Laboratory entry vehicle. Both baseline and magnetic cases were considered, where the magnetic field was provided by a 76 mm diameter, N52-Neodymium permanent magnet with stagnation point magnetic flux density measured as 0.41 T. Thicker forebodies were also considered in order to provide more data points, with measured stagnation point magnetic flux density of 0.29 T. The results showed a significant increase in shock standoff of up to 259% for the 13.5 km · s−1 condition. The ratio of magnetic to non-magnetic shock standoff scaled and increased linearly with the value of the MHD interaction parameter, which partially contradicts analytical predictions from past studies that predicted a power law increase. At 7.4 km · s−1 no increase in shock standoff was observed, however, despite the significant MHD interaction parameter. This could be due to Hall effects although numerical studies should be performed and take into account MHD interaction including Hall effects, in order to better understand the underlying phenomenon occurring in the shock layer.