Aiaa 91-0486 Transient Cryogenic Liquid Discharge in Normal and Micro-gravity

Transient discharge of liquid cryogens from partially filled tanks under micro-gravity is considered. The discharge is made to a low pressure site through a straight tube. The ultimate objective of the study is to predict the transient mass flow rate m(t ) . In addition to m(t), the pressure history in the tank pt(t) is of interest, since the pressure falls below the triple point toward the end of the dump, causing solidification in the tank and/or the discharge line. As first steps, experiments have been performed in normal gravity and attempts are made t o predict m(t) and pt (t) under this condition. Experiments are performed with liquid nitrogen dumped to sites with pressures below the triple point. Homogeneous, equilibrium and non-equilibrium, two-phase critical flow models are compared to the experimental results. Equilibrium and non-equilibrium tank pressure history models are also compared to experimental data.