Theoretical effects of aluminum gel propellant secondary atomization on rocket engine performance

A one-dimensional model of a gel-fueled rocket combustion chamber has been developed. This model includes the processes of liquid hydrocarbon burnout, secondary atomization, aluminum ignition, and aluminum combustion. Also included is a model of radiative heat transfer from the solid combustion products to the chamber walls. Calculations indicate that only modest secondary atomization is required to significantly reduce propellant burnout distances, aluminum oxide residual size, and radiation heat losses. Radiation losses equal to approximately 2-13% of the energy released during combustion were estimated. A two-dimensional, two-phase nozzle code was employed to estimate radiation and nozzle twophase flow effects on overall engine performance. Radiation losses yielded a 1% decrease hi engine 7>p. Results also indicate that secondary atomization may have less effect on two-phase losses than it does on propellant burnout distance, and no effect if oxide particle coagulation and shear-induced droplet breakup govern oxide particle size. Engine 7.p was found to decrease from 337.4 to 293.7 s as gel aluminum mass loading varied from 0-70 wt%. Engine 7,p efficiencies, accounting for radiation and two-phase flow effects, on the order of 0.946 were calculated for a 60 wt% gel, assuming a fragmentation ratio of 5.