DIFFERENCES IN GRAVITY GRADIENT AND GRAVITY JITTER-EXCITED SLOSH WAVES IN MICROGRAVITY

The dynamical behavior of fluids affected by the asymmetric gravity gr adient acceleration and gravity jitter acceleration, in particular the effect of surface tension on partially-filled rotating fluids applica ble to a full-scale Gravity Probe-B Spacecraft dewar tank have been in vestigated. Results of slosh wave excitation along the liquid-vapor in terface induced by gravity gradient acceleration indicated that the gr avity gradient acceleration is equivalent to the combined effect of a twisting force and torsional moment acted on the spacecraft. The resul ts are clearly seen from one-up one-down and one-down one-up oscillati ons of two bubbles in the cross-section of profiles in the vertical r- z plane of rotating dewar, and an eccentric contour of the bubble rota ting around the axis of the dewar in a horizontal r-theta plane. Resul ts of the slosh wave excitation along the liquid-vapor interface induc ed by gravity jitter acceleration indicate that the gravity jitter acc eleration is equivalent to time-dependent oscillatory forces which pus h the bubble in the combined directions of down-and-up and sideward-an d-middleward as the bubble is rotating with respect to rotating dewar axis. Results also show that lower frequency gravity jitter accelerati ons with turn-around directions imposed on the spacecraft container in duce a greater amplitude of oscillations and a stronger degree of asym metry in the liquid-vapor interface geometry than that made by the hig her frequency gravity jitter acceleration. This study discloses the di fferences in slosh wave excitation along the liquid-vapor interface dr iven by gravity gradient acceleration and gravity jitter acceleration which are two major driving forces affecting the stability of the flui d system in microgravity.