Research On The Bubble Dynamics Of Cryogenic Propellant In Multi Phase Interface

Propellant storage has to be safe during the long-term on-orbit refueling missions of the spacecraft.Space spread of cryogenic propellant under microgravity is attaching the wall as the capillarity and the liquid film is thin.As the extremely low boiling point of the cryogenic propellant,when the heat energy is conducted into the tank the superheating in some parts of the tank will lead to the pool boiling which will make great trouble to the managing devices,the tank will be out of service and the pressure inside the tank will increase sharply which may cause leakage or blast.The motion discipline of the bubble is an important element of influencing the heat transfer under the condition of pool boiling,and as well it plays a main role in the efficiency of heat transfer.In a word,it is of great importance to research the bubble dynamics of cryogenic propellant in order to keep the long-term storage and management of cryogenic propellant safe.This thesis firstly research the theory of bubble nucleation in pit under thin liquid film and is researched,and the relation between the pressure inside bubble and the angle of cone pit,the contact angle and the size of bubble has been revealed.Then the simulation of bubble departure on heater under different power is realized,and the changes of necking,width,indeepth and Height/Width during bubble departure are achieved.Finally,the experiment of cryogenic propellant pool boiling under microgravity is designed and conducted,and with the experiment results the influence of different gravity,liquid character,liquid volume,heating power and posture of heater to bubble dynamics is analyzed.The change of CHF and Marangoni effect under microgravity are introduced briefly.