Vincente Cardona, Viviana Lago
DOI Number XXX-YYY-ZZZ
Conference Number HiSST-2022-402
When a spacecraft re-enters Earth’s atmosphere, or in the case of a destructive space debris re-entry, the
problem of proximal bodies is considered. In particular shock/shock interferences can occur, and affect
the structure of the spacecraft or the debris aerodynamics. Depending on the altitude, endured flows
are hypersonic and rarefied, leading to predominant viscous effects. In order to better understand the
impact of rarefaction level on shock/shock interferences, experiments were carried out in the MARHy
wind tunnel (ICARE, CNRS, France). A couple of spheres were placed in a hypersonic rarefied flow
with a free-stream Mach number of 20.2 and a free-stream pressure of 0.07 Pa. Different relative
positions were experimentally explored to identify various types of interferences occurring in this flow,
characteristic of an altitude of 95 km. Results, obtained with the discharge glow visualization method,
allowed the detection of shock waves and the analysis of intensity levels. They revealed that shock-
shock interferences show different behaviors than in a continuum regime or in a less rarefied flow.
Indeed shock waves do not seem to be affected by the interaction with an incident shock. However,
by analyzing the level of intensity near the interacting sphere, differences are observed according the
different positions. This statement is also true concerning the drag forces, measured on the second
sphere with the pendulum technique. This study shows that even if the shock/shock interferences
are not clearly observed visually, the aerodynamics of the following sphere is modified according its
position towards the first one. As a consequence, it can be stated that during the atmospheric re-entry,
the shock/shock interferences play a part on wall flux endured by the spacecraft structure and on the
modification of space debris trajectory.