Spray behavior of non-newtonian fluids: correlation between rheological measurements and droplets/threads formation

DLR ― German Aerospace Center Institute of Space Propulsion Lampoldshausen, Hardthausen 74239, Germany

Abstract

The formation of thread-like structures instead of droplets has been observed in recent studies on the injection of various gels and nonNewtonian fluids through a doublet impinging jet injector. In the present work, it has been studied if a correlation can be found between distinct fluid properties and thread formation. For this task, the tests have been conducted with different classes of fluids with various fluid properties. These classes are: Boger fluids, linear and crosslinked polymer solutions, and silica suspensions. The results show that a correlation exists between thread formation and the extensional behavior of the fluid, in particular, high values of the Trouton ratio. The characterization of the extensional behavior of fluids with a distinct yield stress has been conducted with a capillary rheometer, and the results obtained with this technique are compared to the spray behavior.