PREPARATION AND CHARACTERIZATION OF GELLED FUELS

The advantages and disadvantages of gel propellants and gel propulsion systems are discussed. The preparation of some gel fuels is described using JET A-1 (JP-8) as basic fuel for gelation. A Cowles blade type dissolver apparatus was used for the preparation of the gels using inorganic (fumed silica) and organic (Castor oil derivatives and aluminum octanoate) gelators. The conditions for optimal production results were investigated in several test series. The main production parameters are dissolver disk rotational speed, dissolver diameter, gellant particle size, gellant content, container dimensions, and temperature history of gelation. Several methods for characterization of gel stability and viscosity behavior are discussed, and the results are presented. Gel stability was investigated in conventional and optical centrifuge tests at accelerations up to 2,500 g, and it turned out that all the gels were stable below accelerations of 100 g. Viscosity measurements were performed using rotational cone and plate viscosimeters. The results could be fitted to existing viscosity laws and were used to compute the pressure loss in gel rocket injectors and supply lines. All gels showed strong shear-thinning behavior.