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Frequency and viscous damping of liquids during weightlessness - liquid sloshing characteristics of liquid-vapor interface in zero Bond number environment
The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank before main engine restart poses a microgravity fluid behavior problem. Resettlement or reorientation of liquid propellant can be accomplished by providing the optimal acceleration to the spacecraft such that the propellant is reoriented over the tank outlet. In this study slosh wave excitation induced by the resettling flowfield during the course of liquid reorientation with the initiation of geyser for liquid-filled levels of 30, 50, 65, 70, and 80 percent have been studied. Characteristics of slosh waves with various frequencies excited are discussed. Slosh wave excitations will affect the fluid stress distribution exerted on the container wall and shift the fluid mass distribution inside the container, which imposes the time-dependent variations in the moment of inertia of the container. This information is important for the spacecraft control during the course of liquid reorientation.
This paper concentrates on equilibrium behavior of fluids in low or zero gravity, and sloshing in normal and low gravity. Included are a background and review of the literature, and an introduction to a new equivalent mechanical model.
This paper describes a numerical simulation of the hydrodynamics within the liquid oxygen tank of the Space Shuttle External Tank during liftoff. Before liftoff, the tank is filled with liquid oxygen (LOX) to approximately 97 percent with the other 3 percent containing gaseous oxygen (GOX) and helium. During liftoff, LOX is drained from the bottom of the tank, and GOX is pumped into the tank's ullage volume. There is a delay of several seconds before the GOX reaches the tank which causes the ullage pressure to decrease for several seconds after liftoff; this pressure 'slump' is a common phenomenon in rocket propulsion. When four slosh baffles were removed from the tank, the ullage gas pressure dropped more rapidly than in all previous flights. The purpose of this analysis was to determine whether the removal of the baffles could have caused the increased pressure 'slump' by changing the LOX surface dynamics. The results show that the LOX surface undergoes very high vertical accelerations (up to 5 g) and, therefore, splashing almost certainly occurs. The number of baffles does not affect the surface if the structural motion is assumed; but, the number of baffles may affect the structural motion of the tank.
Role of liquid sloshing in attitude stability equations of liquid propellant space vehicles
A three-dimensional numerical simulation has been performed in order to investigate the hydrodynamics within the liquid oxygen tank of the Space Shuttle external tank after liftoff. The results indicate that the LOX surface undergoes very high vertical accelerations (up to 5 g) and that splashing almost certainly occurs. Although the number of slosh baffles is not found to affect the surface, it is noted that the number of baffles may affect the structural motion of the tank. Surface accelerations are similar to those observed in previous two-dimensional simulations.
Mathematical model for studying liquid slosh effects on rendezvous dynamics by incorporating sloshing dynamics into vehicle motion equation
Simulated low gravity liquid sloshing in cylindrical tanks, emphasizing small liquid depth and smooth wall viscous damping effects
Liquid sloshing under moderately low simulated gravity in oblate ellipsoidal tank geometries
Evaluation of flexible and rigid ring baffles for liquid slosh suppression
The mercury propellant tank system developed for use with solar electric propulsion was studied to analytically determine the resonant frequencies of the tank system and compare them with the anticipated control natural frequency of the spacecraft. The system consisted of a stainless steel spherical shell and a hemispherical elastometric diaphragm. The major analytical tool used was the NASTRAN program. Six mathematical models were developed. Resonant frequencies for six harmonics were obtained for each of the six models considered. The results show that the lowest resonant frequency for the tank system is about an order of magnitude greater than the anticipated control frequency of the spacecraft.
The mercury propellant tank system developed for use with solar electric propulsion was studied to analytically determine the resonant frequencies of the tank system and compare them with the anticipated control natural frequency of the spacecraft. The system consisted of a stainless steel spherical shell and a hemispherical elastomeric diaphram which separates the mercury propellant and the gaseous nitrogen pressurant. The major analytical tool used was the NASTRAN program. Six mathematical models, which represent various amounts of mercury in the tank system were developed. Resonant frequencies for six harmonics were obtained for each of the six models considered. The results show that the lowest resonant frequency for the tank system is about an order of magnitude greater than the anticipated control frequency of the spacecraft.
No abstract available
Liquid sloshing in cylindrical and spherical tanks
Limiting problem of totally wetting liquid sloshing in weightless environment
Hydrodynamic theory for breathing vibrations of a partially filled, cylindrical tank, giving natural frequencies of liquid sloshing as well as pressure distribution
Low gravity liquid motions in a spacecraft are discussed in outline form and on viewgraphs. Free-surface sloshing, liquid draining, liquid reorientation, and sloshing in a bladdered tank are covered. Conclusions and recommendations are given.
Low gravity lateral liquid sloshing in hemispherically bottomed cylindrical tank, noting sloshing fundamental frequency reduction