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Performance characteristics of a cold gas thruster with real gas effects

Özden, Aysu
Cold gas propulsion systems are mainly used for attitude control purposes for space applications since 1960s due to their advantages in cost effectiveness, simplicity, availability, etc. It is important to investigate transient behavior of the thruster of these systems since they operate in a very short period of time, in the order of milliseconds. Both depressurization of the tank and expansion of thrusters to the vacuum, in order to obtain optimum performance in space, result into obtaining low temperatures both in thrust chamber and at the exit section of the nozzle. As a result, propellant’s behavior may diverge from being ideal. Therefore, investigation of real gas effects numerically and comparison with experimental results may give proper information in preliminary design phase. Throughout this thesis, performance tests are fulfilled in a vacuum chamber in order to simulate space conditions for the thruster. Computational fluid dynamics analyses are carried out for ideal gas, Peng-Robinson gas and van der Waals gas models to compare analyses results with experimental data. Open source mesh generator Salome and open source RANS solver SU2 are used for CFD analyses. Results show while real gas models are more accurate to catch pressure peak at the beginning of the operation, all gas models are good enough to provide time require to reach steady state for the thruster for both nominal and low temperature operating conditions. They are also good at predicting time dependent and steady state thrust.