Experimental and numerical investigation of a paraffin-based hybrid rocket engine to brake a 24U microsatellite in a Mars orbit

Hybrid rocket propulsion is an option for small spacecrafts propulsion system, mainly if high thrusts are required, as in missions to Mars. Paraffin/N2O have been chosen as propellant as they combine safety, availability and multitasking: In fact, nitrous oxide can be used for the ignition procedure and makes unnecessary the use of pressurization system. Four small engines are designed to produce energy enough to brake and insert a 24U microsatellite, weighting 20 kg each, in a capture orbit around Mars, respecting the restrictions of the CubeSat Standart. Numerical work have been done in order to evaluate a proper mechanism to simulate the combustion process and to predict the behaviour of the flow in two different environment conditions: space and atmospheric. Results show that reduced mechanisms that takes into account the N2O dissociation have a good performance in simulating the engine operation. Since the engine is designed to space conditions, shock waves, vortex formation and displacement of the boundary layer at the nozzle could be predicted and are expected during the test campaign. Experimental work to evaluate the performance is under investigation in the Space Propulsion Laboratory at the School of Aerospace Engineering.