Book Description

With the increasing size of space vehicles and their larger diameters which lower the natural frequencies of the propellants, the effects of propellant sloshing especially since at launch a very large amount of the total weight is in the form of liquid propellant. With increasing diameters the eigenfrequencies of the propellant become smaller and shift closer to the control frequency of the space vehicle. Furthermore, the oscillating propellant masses and the corresponding forces increase considerably. A relatively simple means of avoiding strong dynamic coupling can be achieved by subdivision of the container by radial or circular walls. This results in smaller sloshing masses and higher eigenfrequencies. Another possibility is the clustering of tanks with small diameters which has the disadvantage of a weight penalty. For stability investigations the influence of the oscillating propellant has to be known. For this reason forces and moments of the propellant with a free fluid surface in a container of circular ring sector cross section performing forced oscillations must be determined. This will be performed with the assumption of irrotational, frictionless, and incompressible liquid. Linear equivalent damping is introduced with the help of a mechanical model describing the fluid motion. It has to be determined by experiments.