Abstract: Heat load in spacecraft and aerospace shuttles, which generally work in space and upper atmosphere, is increasing, while the cooling ability of these vehicles is poor. This study researchs the atomization degree of water spray under the superheated condition, which can exert direct influence on the cooling ability of aerospace vehicles. A model for breakup of a single water droplet caused by bubble growth and aerodynamic force under the superheated condition is established, and a model for mass transfer and heat transfer is also proposed. The Lagrangian method is used to track and integrate all the droplets in the system. The effect of different degrees of superheat on spray atomization and droplet temperature is calculated using MATLAB. Then the degree of effect superheat degree on spray cooling is concluded. The calculation results indicate that the atomization degree under the flash boiling condition is much better than that under the sub-cooled condition. The droplet temperature will rapidly approach the boiling temperature under the superheated condition. The higher degree of superheat, the higher atomization degree, and thus the better spray cooling ability theoretically.

Key words: water spray, flash boiling, atomization, superheat degree, spacecraft thermal control