Coupled dynamics of variable-mass multi-tank liquid-filled spacecraft with a flexible appendage

Abstract

During on-orbit operations, liquid propellant is continuously consumed in spacecraft systems. To more accurately investigate rigid–liquid–flexible coupled dynamic behavior during spacecraft maneuvers, this paper accounts for the time-varying system parameters induced by propellant consumption and conducts coupled dynamic modeling, numerical simulation, and characteristic analysis of a variable-mass, multi-tank, liquid-filled spacecraft with flexible appendages under large-amplitude liquid sloshing conditions. First, the variable-parameter center-of-mass surface constraint model is adopted to characterize the evolution of sloshing dynamics during propellant consumption. Then, the flexible rod is modeled using a geometrically nonlinear formulation, and the spacecraft rigid–liquid–flexible coupled dynamics are established based on Kane’s method. Finally, numerical simulations are performed to systematically examine the influences of propellant consumption, flexible appendage configuration, and maneuvering states on the spacecraft’s large-angle three-axis stabilized attitude maneuver responses. The results show that multi-tank configurations are more susceptible to strong nonlinear coupling with flexible appendages than single-tank systems. Strong nonlinear coupling phenomena observed under unconsumed propellant conditions may not persist during propellant consumption. Moreover, the relative spatial arrangement between the flexible appendages and the liquid tanks significantly affects their coupling characteristics, and the spacecraft angular velocity disturbances are related to the maneuvering states of the flexible appendages.