Experimental and Numerical Study on Coupled Dynamics of Liquid Propellant and Spacecraft Motion Induced by Impact

Liquid propellant sloshing in tanks subjected to low-gravity impacts, free-fall landings, and docking shocks can destabilize spacecraft by shifting their center of mass and imposing additional loads. Because on-orbit and drop-tower tests are costly and limited, this study develops a simple, repeatable drop-impact experiment that reproduces low-gravity and impact-induced liquid jets. High-speed imaging quantifies the coupled fluid–rigid body motion in ethanol-filled and wax-filled tanks. A two-phase CFD solver is coupled with rigid body dynamics and validated against the experiments, successfully reproducing the reduced rebound height and increased liquid-induced loads.