Optimization of a small satellite tridyne propulsion system

This paper presents the integrated modeling and optimization of a Tridyne™-based small satellite propulsion system. A detailed integrated model is developed to compute propellant thermodynamic properties throughout the entire propulsion system, from the propellant tank through the valves, regulator and thrusters. The simulation uses a compressible flow model incorporating both friction and heat transfer to predict these properties. The detailed model was validated against, and showed good agreement with two existing professional software tools. While the detailed model proved to be accurate, it was computationally expensive, necessitating the development of a fast screening model for use in optimization. The screening model utilizes polynomial curve fits for NIST thermodynamic data, lumped pipe flow calculations and larger time steps. The NSGA II multi-objective optimization routine, employing the screening model, found a set of non-dominated designs that showed the tradeoff between the two objectives of maximizing ΔV and minimizing tank pressure. These non-dominated designs are classified into five design families and three point designs were chosen for further detailed analysis and comparison. This approach shows great promise for preliminary designs of highly integrated small satellite propulsion systems.