Design And Simulation Study On Nitrous Oxide Monopropellant Engine System

In this dissertation, an overall plan of blow down feed system of 10 Newton nitrous oxide monopropellant engine was designed and specified, which is including the thermodynamic calculation of chamber, parameters design of propellant tank, pipeline, filter, catalyst chamber, injector and nozzle. Meanwhile, the preliminary selection was made on the valve. Then, the simulation of major components and the critical channel of the system were carried out.Among them, firstly, the simulation study on the working process of N2 O tank, quantificationally, stated the advantages of deliverability of N2 O, for which N2 O has self-pressuration characteristic, comparing with the other traditional propellants, and investigated the influence of the initial temperature, initial filling factor, tank size, propellant supply phase on the characteristic. It also analyzed the heating power, which could made the N2 O tank of blow down feed system have the performance of regulated pressure feed system, based on the optimal thermal control design of tank.Secondly, the numerical investigation on the liquid N2 O flowing through the thruster header, the critical part of the system, was carried out in connection with high vapor pressure of N2 O, which is susceptibility to heat. Then the law of temperature changing of the main components of thruster header and the two-dimensional flow field in the supply line were obtained. By which, the effects of gas-liquid multiphase flow of on pressure and mass flow rate before injection were analyzed and some measures adopted to weaken or remove the effects were put forward.Thirdly, this dissertation analyzed the influences of heat insulation catalyst chamber and inlet mass flow rate on its internal flow field based on the heat non-equilibrium hypothesis within the fluid, which is in the catalyst chamber, and the catalyst bed. It also discussed the optimal length of catalyst bed.Finally, the expansion ratio of a monopropellant engine nozzle was optimized based on a simple engine system quality model and the performance of the nozzle was calculated and analyzed.