Turbo-pump fed miniature rocket engine

The increasing application of micro-satellites (from 10kg up to 100kg) for a rising number of various missions, demands the development of new propulsion systems. Microsatellites have special requirements for a propulsion system such as small mass, reduced volume, and very stringent electrical power constraints. Existing propulsion systems often can not satisfy these requirements. Recently the development of a bipropellant thruster complying with these requirements was initiated. The main development goal of this effort was the utilization of ethanol in combination with hydrogen peroxide (H₂O₂) as a non-toxic propellant combination. The bipropellant thruster consists of four subcomponents: the propellant pumps, a decomposition chamber (catalyst), a turbine, and the thrusters itself. The turbine is driven by the decomposed hydrogen peroxide and coupled with a power generator. The produced power is then used to generate a pressure head in order to deliver the propellant into the combustion chamber. This system therefore constitutes a self-sustaining system and does not rely on the limited power supply of a micro-satellite. All the components were individually tested and the results are presented here. The micro-gear pump successfully delivered the required mass flow rate with the necessary pressure. The turbine was tested with a cold air flow and has not yet reached the designed power output. A redesign of the turbine is ongoing. The decomposition chamber was tested and it was verified that the H ₂O₂ decomposes nearly to 100%. The thruster was successfully ignited and operated for more than 45 minutes. The measured thruster wall temperatures indicate a highly efficient combustion when only ethanol and oxygen are present in the combustion chamber. The injection of water however, tends to produce flame outs. A redesign of the propellant feed system is ongoing and expected to improve the thruster operation.