Initial Experimental Investigations of Self-Pressurizing Propellant Dynamics

Hybrid rockets commonly use nitrous oxide as a self-pressurizing oxidizer, but no comprehensive models exist for predicting the performance of such a system. To aid in the development of such a model, an experimental apparatus has been constructed with a transparent cylinder that allows for optical measurements as well as pressure, temperature, and mass flowrate measurements. Carbon dioxide has been identified as an analog for nitrous oxide, facilitating laboratory-scale testing. Initial results of tests with this system show that there is significant boiling within the liquid and that the propellant is not maintained in thermodynamic equilibrium. Furthermore, both supercharge configuration and mass flowrate strongly affect the dynamics of self-pressurizing propellants.