Behavior of Subcooling Jet Injected into a Bulk Liquid in a Tank under Normal- and Micro-gravity Conditions

In the future exploration for deep space, cryogenic fluid will be used as propellant and oxidizer for spacecraft. The increasing of tank pressure is caused by boil off gas (BOG) induced by heat leakage into the tank from the surrounding environment. Reducing of BOG is derived from destroy of thermal stratification of a bulk liquid in the t ank. Therefore, development of Thermodynamic Vent System (TVS) for the purpose of prevent of loss of cryogenics propellant in future space system is needed. TVS combining jet mixing, spray, and heat spot removal by forced cooling using Electro-hydro-dynamics is under consideration by authors. Destroying thermal stratification without venting by using subcooling mixing jet will be developed for a key technology of TVS. In this paper, the behavior of the mixing jet by visualization method and description about the motion of the jet with a simple one-dimensional model without heat transfer is reported. In our simple dynamic model, a single sphere droplet as the tip of the jet is assumed and an equation of the motion is applied for the droplet. The results of analysis model and experimental data taken by shadowgraph system are compared. In addition, microgravity experiment is performed, and flow behavior in microgravity is described.