Rheological and atomization behavior of glycyrrhizic acid based supramolecular gel propellant simulant

Gel propellant has attracted much more attention due to its advantages in reducing the leakage risk, adjustable thrust, being capable of multi-time ignition and easy handling. Conventional polymeric gellant or inorganic gellant based gel propellant suffered from several problems, such as high viscosity, inadequate atomization and insufficient combustion. As several pioneer reports, low-molecular weight gelators (LMWGs) based supramolecular gel fuels could exhibit good shear-thinning properties. The corresponding atomization property, however, is still unclear and needs further study. Herein, glycyrrhizic acid (GA) based hydrogel was employed as supramolecular gel propellant simulant, and its rheological and atomization behavior were well investigated. The 1.0%− 2.0% GA hydrogel exhibited a certain mechanical strength with storage modulus between 30 and 90 Pa. The shear viscosity of hydrogel decreased sharply under low shear rate (below 2 s−1), and then further decreased to 10−2-10−3 Pa.s under higher shear rate (2–1000 s−1). The resulting shear viscosity of 1.0% GA hydrogel was close to the magnitude of pure water, and an order of magnitude higher than pure water for 1.5% and 2.0% GA hydrogel systems. The atomization performance of GA hydrogel was investigated under both self-impinging doublet injector and centrifugal injector, it was found that the spray pattern, breakup length of liquid film and spray cone angle of 1.0% GA hydrogel were all similar as the pure water under two kinds of injectors, while the atomization performance degradation for 1.5% and 2.0% GA hydrogel. It was concluded that the shear viscosity plays an important role in determining the atomization properties for GA based hydrogel.