Design optimization of a thrust chamber using a mass-based model to improve the geometrical and performance parameters of low-thrust space propulsion systems

A large portion of the wet and dry mass budget in any space system is assigned to the propulsion system. Each of these depends on the engine system design values. Any effort to decrease the mass of space systems demands an additional effort to reduce the propulsion system mass, which in turn requires a complete review of the engine design. Thus, proposing a computational model derived from the engine design and based on minimum system mass is necessary. The present computational research developed a propulsion system design strategy for liquid propulsion systems to optimize take-off mass and satisfy the thrust required under performance and structural constraints. Improvement of the geometric and performance variables and component mass using a mass-based model for optimization process is investigated. The method uses a hybrid genetic algorithm sequential quadratic programming as an optimizer. The mass-based formulation problem is solved using a hybrid optimization algorithm with a genetic algorithm as the global optimizer and sequential quadratic programming as the local optimizer starting from the solution given by the genetic algorithm. The convergence of the optimization algorithm is improved by introducing an initial solution based on genetic algorithm. Comparison of the proposed design optimization model with a real space propulsion system indicates that the performance of the proposed algorithm significantly improved the final results. While propellant mass, engine consumption rate and engine geometric dimensions decreased, specific impulse increased. All of these decreased the total mass of the space propulsion system.