Development of an Experimental Demonstrator Unit Using Nitrous Oxide/Ethylene Premixed Bipropellant for Satellite Applications

In the continuously growing scientific area and market of satellite propulsion systems, the need for replacement of toxic propellants like Hydrazine with human- and environment-friendlier substances called Green Propellants has arisen. Within the context of this research initiative and in terms with the REACH-Regulation, the German Aerospace Center (DLR) in Lampoldshausen is developing and testing an experimental demonstrator based on the technology of Nitrous Oxide Fuel Blends, which involve the mixture of Dinitrogenmonoxide with Carbon Hydrides. Specifically, at the testing facility of M11, the combination of Nitrous Oxide (N2O) and Ethylene (C2H4) as a premixed Bipropellant for applications in satellite propulsion modules is being examined. The combination of a high specific impulse (320s at 10 bar, e=40 against vacuum) with the classic advantages of lighter feed and storage systems connected to monopropellants, render the mixture a strong candidate for usage as a green propellant in satellite applications. Within this project, the development of different injection systems has taken place, in order to examine the combustion properties of the propellant in different phases (gas or liquid) and in different mass flow rate regimes. By taking into consideration the two phase flows present in satellite thruster firings due to the injection against vacuum, the tests ran so far involve a gaseous mixture. Since the outlook of the project aims for a liquid storage and injection of the propellant, a simulation tool describing the necessary conditions for the phase change (condensation or evaporation) was also generated. The absence of accurate experimental data for the state of the mixture in the 2 phase region renders the simulation a preliminary tool of the design of the mixture’s liquefaction facility. Further CFD Simulations in combination with experimental tests for the full description of the combustion properties and the mixture’s physical characteristics in gaseous and liquid phase are planned for the future.