Investigation of Effect of Rheological Behavior of Gelled Propellant on Atomization Characteristics of Swirl Injector

The Gelled propellants have a promising future for aerospace applications because of possessing the advantages of both solid and liquid propellants. A gel propellant is a liquid propellant whose rheological properties have changed by the addition of gellant and other additives. The rheological properties of the propellant have a significant influence on the atomization process. In this paper, the rheological properties of the gel propellant are introduced. Then, the effect of gel propellant properties on the atomization in the swirl injector has been investigated. Subsequently, some important points for designing a swirl injector that can influence enhancing the atomization quality of the gelled propellant are presented. The results of the studies revealed that higher initial viscosity of the gelled propellant compared with the mother liquid propellant cause increase in the discharge coefficient, the size of droplet diameter, and the breakup length of the gel sheet while causing a decrease of spray cone angle in the swirl injector compared with liquid propellant and in the point of view of influenced by the size of droplet diameter on the gel propulsion system. Considering the shear thinning effect of the gel propellant and ability to atomization of gelled propellant by swirl injector, to improve the quality of the atomization of gel propellant, the design of the swirl injector should be such that the shear rate applied on the gel propellant should be increased to conquer the initial viscosity of the gel.