EFFECT OF A BAFFLE ON SLOSH WAVES EXCITED BY GRAVITY GRADIENT ACCELERATION IN MICROGRAVITY

The dynamical behavior of fluids affected by an asymmetric gravity-gradient acceleration is studied. The effect of surface tension on rotating fluids, applicable to a partially filled full-scale Gravity Probe-B Spacecraft Dewar tank with and without installing baffle boards, is studied. Results of slosh-wave excitation along the liquid-vapor interface induced by gravity-gradient acceleration are examined. These results indicate that the gravity-gradient acceleration is equivalent to the combined effect of a twisting force and torsional moment acting on the spacecraft. The results are clearly seen from the eccentric contour of a bubble revolving around the axis of a Dewar in a horizontal r-theta plane. As the viscous force across the liquid-solid interface greatly contributes to the damping of slosh-wave excitation, installing baffles in the rotating Dewar is expected to dampen these waves. Results show that the damping effect provided by a baffle reduces the amplitude of slosh-wave excitation and lowers the degree of asymmetry in the liquid-vapor distribution. Computation of bubble (helium vapor) mass-center fluctuations also verifies that rotating a Dewar with baffles installed produces less fluctuation than without the baffles.