Research On The Flow Boiling Of Cryogenic Medium In Pipe

During the operation of the satellite,attitude control is an important aspect of satellite control.This thesis is based on a LO2/Methane small thrust engine applied in a project.Numerical simulation and experimental investigation were performed to study the characteristic of flow boiling of liquid oxygen and liquid nitrogen according to the partameter of temperature and mass flow rate.Firstly,the flow boiling characteristic of liquid oxygen is studied through numerical simulation,the flow boiling heat transfer coefficient is about 1-3 times larger than single phase heat transfer coefficient?When the heat flux is larger and local dry appears in pipe,the heat teansfer coefficient rapidly decreases to a low degree,sometimes even lower than single phase heat transfer coefficient.The influence of heat flux and mass flow rate to heat transfer coefficient ?wall temperature and flow boiling pressure drop is also analysed.Based on the research above,The influence of heat flux and mass flow rate to heat transfer deterioration is also studied.Then,experimental is performed using liquid nitrogen.The pipe is 300 mm long,10 temperature measuring point is put along the pipe uniformly,2 pressure measuring point is put on the inlet and outlet respectively.Based on the temperature and pressure measured,the inner wall temperature ?local heat transfer coefficient ?dryness along the pipe are conculatedFinally,the experimental data is compared with data conculated by programs of heat transfer coefficient and flow boiling correlations.