Liquid-Propellant Droplet Combustion and Cluster-Behavior at Supercritical Conditions

摘要

A systematic investigation of superoritical droplet vaporization and cluster behavior has been conducted based on the complete conservation equations in both the gas and liquid phases. The research work addresses a variety of fundamental issues related to droplet vaporization and dynamics at realistic conditions typical of liquid-propellant rocket combustion devices. A unified treatment of real-fluid thermodynamics has been developed based on fundamental theories. Special attention was given to the thermodynamic non-ideality and transport anomaly in the transcritical regime. A series of calculations has been performed to examine the cluster behavior of liquid oxygen (LOX) droplets in both sub- and super-critical hydrogen environments. Results show that pressure has strong effect on droplet interactions, while the temperature effect is relatively minor at high pressures. The hydrogen density plays a decisive role in determining droplet interactions through its influence on the temperature and mass fraction gradients at the LOX droplet surface. The characteristics of LOX droplet vaporization in forced-convective environments has also been studied. A dimensionless parameter We/Oh 1/2, which represents the ratio of aerodynamic and viscous forces, is found to be the major factor determining the droplet deformation under supercritical conditions. Results of droplet lifetime are well correlated as a function of the initial droplet Reynolds number and pressure. Finally, the interactions between two droplets moving in tandem in supercritical convective environments were investigated in detail.