Analysis of Reentry and Break-Up Forces from Impulse Facility Experiments and Numerical Rebuilding

Abstract

This paper shows new findings for the break-up of large spacecraft during reentry into Earth’s atmosphere. The break-up scenario at high altitude drives the ground impact area for parts surviving the reentry. Therefore, based on a combined experimental and numerical analysis of the reentry of the International Space Station (ISS), loads at the module connections have been assessed. In this study, experiments were conducted in an impulse facility to determine the aerothermodynamic forces that apply to models of three components from the ISS. This paper marks the first approach to the experimental testing of complex geometric models coupled with a ground-to-flight scaling of the resulting internal stress. A high-speed schlieren setup was used to record the movement of the multibody free-flight models. A 3D positional analysis tracked the bodies separately. The experimental situation was simulated using the eilmer4 computational fluid dynamics code. A comparison of the experimental and simulated flowfield shows a reasonable agreement in shock structure and resulting forces. The forces were then scaled from testing to flight, extrapolated along a trajectory path, and transformed into spacecraft internal stress. While the resulting forces are significant, it is shown that these forces are significantly smaller than the yield strength of structural materials. Although no aeroheating was simulated in this study, the separation of the large segments of the ISS might not be driven by the mechanical forces alone. This study shows that comparatively simple shock tunnel experiments offer a comprehensive high-fidelity analysis of the interbody forces of complex multibody structures.