Liquid Acquisition Devices for Superfluid Helium Transfer (without figures)
Michael J. DiPirro
Code 713
NASA/Goddard Space Flight Center
Greenbelt, MD 20771
Published in Cryogenics 30, 193 (1990)
To transfer superfluid helium (He II) in the milli-g or micro-g environment in orbit, it is necessary to provide a reasonably steady supply of liquid to the inlet of the pump in the supply dewar. To accomplish this without providing an artificial gravity through acceleration requires a liquid acquisition device. Fluid swirl and electrostatic devices have been proposed to orient the fluid. However, the simplest mechanism appears to be the use of surface tension or the thermomechanical effect. This paper examines four concepts for providing He II to the inlet of a thermomechanical pump. The devices are a distributed thermomechanical pump, a distributed pump with a main thermomechanical pump, a screened channel system, and a vane/sponge combination. Calculations on the efficiency of these types of liquid acquisition devices are made using laboratory data from tests involving small scale devices where applicable. These calculations show that the latter two types of liquid acquisition devices are the most efficient. Questions on the probability of cavitation and the effect of the residual shuttle acceleration on their operation remain to be answered, however. 
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