Rheological and Thermal Behavior of Gelled Hydrocarbon Fuels

Rocket propulsion systems are bound to energetic propellant combinations to provide the best performance in conjunction with smallest possible storage volume. The application of a gelled fuel and a gelled oxidizer potentially combines the advantages of conventional solid and liquid propellants without some specific disadvantages of both individual systems. Gelled JP-8 and RP-1 fuels have been used to study the rheological behavior of gelled hydrocarbons. For all investigations fumed silica was used as a gelling agent with 4 to 7 wt%. Alongside a description of the gel mixing process, the paper discusses viscosity, stability, thixotropic behavior, and the viscoelastic properties of the gels through their storage and loss moduli as a function of gelling-agent amount. An extended Herschel-Bulkley model was applied to describe the viscosity characteristics of the hydrocarbon gels. Differential scanning calorimetry measurements showed only a slight influence of the gelling-agent amount on the heat of vaporization of the gels. The ungelled hydrocarbons featured a higher heat of vaporization than the gels.