Formulation, Rheology and Impact Sensitivity of "Green" Gelled Propellants with and without Metal Additives

Currently, most space propulsion systems use hydrazine and its derivatives, a toxic, carcinogenic monopropellant. These systems entail logistic and environmental difficulties. Significant efforts are underway to develop "green" propellants which do not have these undesirable characteristics. Among those considered include ionic liquid compounds such as HAN and ADN. These blends offer similar or better Isp values to hydrazine but offer reduced costs in handling and lower environmental effects. Gel propellants offer a number of advantages over their liquid and solid propellant counterparts, including higher theoretical specific impulse, restart and throttling capabilities, and safer transport and handling properties. These advantages are offset by a number of drawbacks including inadequate atomization and large feed pressure requirements to force the gelled propellant through the injector at the required flow rates. This present work seeks to investigate optimal "green" propellant formulations based on their stability, homogeneity, sensitivity, along with an array of rheological properties in order to characterize the flow behavior of the gelled propellant at every stage in its life cycle.