MOVING PULSATING BALL EQUIVALENT MODEL AND ITS VALIDATION EXPERIMENT FOR LARGE AMPLITUDE LIQUID SLOSH IN GRAVITY ENVIRONMENT

Modern spacecraft usually carry large amounts of liquid propellant. In the process of attitude change, the liquid fuel may slosh violently due to the action of inertial force and gravity, resulting in additional sloshing force, which will have an important impact on the spacecraft. In order to obtain the law of liquid sloshing and meet the requirements of on-board computer real-time calculation, a dynamic model for equivalent liquid sloshing is studied and verified in this paper. Firstly, the moving pulsating ball model (MPBM) of large liquid sloshing motion is extended to the gravity environment. Based on the Newton-Euler dynamic equation of the moving pulsating ball and the energy relation in the process of "breathing movement", the expression of the normal component of the sloshing force is derived. In addition, the equivalent model of liquid not involved in sloshing is introduced to make the calculation of liquid centroid position more accurate. Compared with the experimental data in the references and the calculation results of computational fluid dynamics (CFD) software, the effectiveness of the improved MPBM under large amplitude sloshing and zero momentum maneuver is verified. Also, based on the equivalent model, the effects of different time series of impulse excitation on liquid sloshing response in spacecraft are studied. Finally, an experimental platform for precise measurement of liquid sloshing force is designed and built to verify that the MPBM can also well reflect the variation trend of sloshing force in the liquid sloshing of equivalent non spherical tank. The research work of this paper has important reference value for the further study of rigid-liquid coupling dynamic behavior of liquid filled spacecraft in gravity environment.