Analytical Investigation of Propellant Slosh Stability Boundary on a Space Vehicle

Abstract

The effect of propellant sloshing upon the stability of a liquid-propelled space vehicle in a high-g environment has been studied extensively. For a typical space vehicle with thrust vector control and a single slosh tank, the Bauer slosh danger zone is located between the vehicle center of mass and the center of percussion while ignoring effects, like aerodynamics and axial acceleration. If the slosh mass is located between these two locations, baffles may be required to provide additional damping for stability. Although this criterion is widely used in the launch-vehicle flight control community, its application is limited to the aforementioned configuration and assumptions. In this work, the methodology behind the classic single-tank criteria is extended to other tank configurations and includes previously ignored effects. First, a vehicle with a single centerline tank and a pair of outboard reaction jets, rather than thrust vectoring, for attitude control is studied. Second, the impacts of aerodynamics and vehicle axial acceleration on the classic single-tank criteria are analyzed. Finally, the variation of the classic danger zone for a tandem tank configuration, where the tanks are located along the vehicle centerline or symmetrically offset from the centerline, is investigated.