Development and testing of a lab-scale test-bench for hybrid rocket motors

A hybrid rocket motor is a type of propulsion system where a solid fuel is placed inside the combustion chamber and the gaseous or liquid oxidizer are stored in external tanks and injected into the motor by means of a feed and injection systems. The propellant configurations make the hybrid technology safer than the solid rockets and less complex than the liquid systems. Due to these relative advantages the Aero-Thermo-Mechanics department (ATM) at the Université Libre de Bruxelles (ULB) in collaboration with Royal Military Academy of Belgium (RMA) designed and manufactured a lab scale test bench with the goal to test a new model of the ULBHRM, a liquid nitrous oxide – paraffin-based hybrid rocket motor. The test bench was conceived to be flexible in order to carry out fundamental research on hybrid propulsion and to allow the use of various sensors and different propellant combinations. The test stand comprises of the thrust chamber, the liquid nitrous oxide tanks and the shelter for personnel/staff with the control system and data acquisition system. The horizontal test bed was designed to be friendly mounted and transported. A LabView program integrated with the data acquisition system using the NI USB-6218 and tow NI USB-9215 cards, and a control box manufactured at the ATM department allows us to automatically transfer the nitrous oxide from the commercial cylinders to the test bench tank, control the N₂O main valve which determines the burning time, pressurize the oxidizer tank, and the purge system to extinguish the combustion using nitrogen and to also get rid of the pressure remained in the feed system. In this work, we present the project and the qualification test for the entire system, which includes the test facilities and the new ULBHRM hybrid motor to validate the test stand, the motor was designed to deliver �� ���� thrust with the possibility to increase this value by ������% through controlling the oxidizer mass flow rate.