Effect of catalytic bed porosity and mass flow rate on decomposition and combustion processes of a HAN-Based monopropellant thruster

Hydroxylamine nitrate (HAN) is widely considered as a green, non-toxic liquid propellant. Here, given the complex chemical and physical processes occurring in a HAN-based thruster, the steady-state working of such a thruster was studied using a numerical simulation approach. The catalytic decomposition and combustion processes of a HAN/methanol propellant were simulated as a chemical reaction model consisting of 15 species and 11 elementary reactions. By establishing a three-dimensional model of the HAN-based thruster validated by the experiment. In addition, the effects on the performance of the HAN-based thruster of varying fore-catalytic bed porosity, after-catalytic bed porosity and the inlet mass flow rate were investigated. The results showed that the porosity of the fore-catalytic bed had the significant effect on the catalytic decomposition and combustion reaction of the propellant, and the combustion characteristics of the fuel were improved with the change of the porosity of the after-catalytic bed. In addition, the most obvious finding to emerge from this study was that the performance of thruster was improved with the increase of inlet mass flow rate. The results from this paper were expected to provide a reference for the future design and performance evaluation of HAN-based thrusters.