An Open-source Solver to Model the Catalytic Decomposition of Monopropellants for Space Thrusters

ABSTRACT: This paper presents a solver for the CFD (computational fluid dynamics) modeling of catalytic chambers in monopropellant thrusters based on the open-source OpenFOAM® (Open Field Operation and Manipulation) framework. A model was formulated and used to simulate the physical and thermochemical processes taking place inside the catalytic chambers of the monopropellant thrusters. The code integrates reacting gas flow in porous media, with mass and heat transport. The most important implemented functionalities were the separation of two reactive gases, one transient reactive gas flowing between the catalyst bed interstices (interstitial gas), and another static reactive gas on the surface of catalyst particles, or pellets (surface gas). Homogeneous and heterogeneous reactions occur on the interstitial gas and the catalyst particle, respectively. A flexible definition of porous properties, a calculation of multicomponent diffusion-flux mass, a diffusion mass coeffcient, a mass transfer coeffcient, and a heat transfer coeffcient were implemented as well. Experimental and analytical studies about hydrazine monopropellant thrusters in the literature were used to the case tests and verification of the solver. Temperature and mass fraction fields were simulated and compared. The results of the temperature profile are in agreement with experimental and theoretical studies found in the literature, and mass fraction presents some differences.