ORBITAL SPACECRAFT CRYOGENIC HELIUM DEWAR SLOSHING DYNAMICS DRIVEN BYGRAVITY GRADIENT ACCELERATION ASSOCIATED WITH SLEW MOTION

The mathematical formulations of orbiting spacecraft sloshing dynamics for a partially filled liquid of cryogenic superfluid helium II in a Dewar container driven by the gravity gradient acceleration associated with slew motion are studied. The Advanced X-ray Astrophysics Facilit y-Spectroscopy (AXAF-S) spacecraft is chosen as a practical example in this study. Explicit mathematical expressions for the orbital gravity gradient acceleration associated with the slew motion acting on space craft fluid systems are derived. The numerical computation of sloshing dynamics is based on the non-inertia frame spacecraft bound coordinat e and the solution of time-dependent, three-dimensional formulations o f partial differential equations subject to initial and boundary condi tions. The explicit mathematical expressions of boundary conditions wh ich treat the capillary force effect of sloshing dynamics on the liqui d-vapor interface in a microgravity environment are also derived. This study discloses the capillary force effect of sloshing dynamics that governs liquid-vapor interface fluctuations driven by the gravity grad ient acceleration associated with slew motion. This sloshing dynamics affects the stability of the orbital spacecraft fluid system in a micr ogravity environment.