重力环境下液体大幅晃动运动脉动球模型及实验研究

现代航天器通常携带大量的液体推进剂, 在航天器的姿态发生变化的过程中, 由于惯性力和重力的作用, 可能会导致液体燃料发生剧烈晃动, 由此产生附加的晃动力会对航天器造成重要影响. 为了得到液体晃动的规律并满足星载计算机实时计算的要求, 本文研究并验证了一种用于等效液体大幅晃动的动力学模型. 首先将液体大幅晃动运动脉动球模型MPBM推广到重力环境中, 通过脉动球的牛顿?欧拉动力学方程和“呼吸运动”过程中能量关系式, 推导出晃动力法向分量的表达式. 同时, 引入不参与晃动的液体的等效模型, 使得液体质心位置的计算更加准确. 通过和文献中实验数据以及CFD软件的计算结果进行比较, 分别验证了推广的MPBM模型在大幅晃动、零动量机动工况下的有效性, 并基于该等效模型, 研究了脉冲激励的不同时序对航天器中液体晃动响应的影响. 最后, 设计并搭建了用于精确测量液体晃动力的实验平台, 验证了MPBM模型在等效非球形储箱的液体晃动时也同样可以很好地反应出晃动力的变化趋势. 本文的研究工作对进一步研究重力环境中充液航天器刚–液耦合动力学行为具有重要的参考价值. 

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.