Optimization of a Hybrid Rocket Motor with a Volume-Limited Fuel Grain

Hybrid rocket propulsion is a promising compromise between the solid and liquid types, that has not fully matured yet mainly due to industry conservatism. The purpose of this work was evaluation of different optimization aspects related to a hybrid system containing a volume-limited fuel grain. Thermochemical calculations were performed to find the “best” oxidizer-fuel combination. The H2O2-Polyester combination showed the most promising results (in ρˑIsp) for volume-limited systems. An optimization scheme based on a genetic algorithm was formulated, developed, and implemented in MATLAB to support the effort of optimizing the whole motor for a specific mission (the Goddard Problem). Three grain types were used as test cases to demonstrate the ability: the Central Cylindrical Port, the Wagon Wheel, and the “Jagged Star”. The “Jagged Star” type showed the most promising results, but only by a small difference (-6% in cost function value) from more conventional designs. Improvement in the models used and manufacturing capabilities (such as Additive Manufacturing) are key to realize optimized designs.