Evaluation of Fluid Behavior in Spinning Toroidal Tanks

An experimental study was conducted to evaluate propellant behavior in spinning toroidal tanks that could be used in a retropropulsion system of an advanced outer-planet Pioneer orbiter. Information on propellant slosh and settling and on ullage orientation and stability was obtained. The effects of axial acceleration, spin rate, spin-rate change, and spacecraft wobble, both singly and in combination, were evaluated using a Vs-scale transparent tank in \-g and low-g environments. Liquid loadings ranged from 5 to 96% full. The impact of a surfacetension acquisition device was assessed. Testing simulated the behavior of F 2 /N 2 H4 and N2O4/MMH propellants. Results are presented that indicate no major fluid behavior problems would be encountered with any of the four propellants in the toroidal tanks of a spin-stabilized orbiter spacecraft.