Theoretical Approaches on the Influence of Non-Linear Material Properties of Gel Propellants on the Flow in Injectors

Abstract

The steady flow behavior of gel fuels in tubes has been investigated by the analysis of the formulated governing equations. The extension of the common power-law model by a constant yield stress allows a more accurate description of the flow behavior especially in regions with low and very low shear rates. This equation has been fitted to the experimentally measured shear stress traces of a Nitromethane-gel. The governing equations for the tube flow are deduced and discussed. The influence of the ratio of the yield stress to the occuring wall shear stress on the flow properties is investigated for a Nitromethane-gel and a Jet A-1 / Aerosil-Gel. It can be seen, that a region with plug flow behavior occurs in the core region in tube flows. The size of the plug flow region increases with the increasing ratio of the yield stress to the occurring wall shear stress.