Preliminary tests on thermal ignition of ADN-based liquid monopropellants

Preliminary tests on thermal ignition with ADN-based liquid monopropellants FLP-106 and LMP-103S have been conducted using two thermal ignition methods. Investigated thermal ignition methods were based on a pilot flame igniter and a glow plug. Results indicated that ADN-based propellants offer different behavior compared to conventional monopropellants. At first the propellants needed to be conditioned by evaporating the water portion. In this phase the heat transfer from the igniters to the propellant played a major role for the ignition time delay. After evaporation of the water the propellant decomposition could be initiated. It was found that with thermal igniters the internal energy feedback from decomposing propellant portions was insufficient to condition newly injected propellant portions upstream. An external heat feedback is necessary to sustain water evaporation and hence propellant combustion. While tests with a pilot flame igniter and a cylindrical combustion chamber were not successful, glow plug ignition showed satisfying decomposition and ignition behavior. With the conducted preliminary thermal ignition tests a profound knowledge could be gained concerning propellant ignition behavior of FLP-106 and LMP-103S. Furthermore similarities and differences of both propellants could be analyzed and allow improvement of thermal ignition methods for future research activities. •Thermal ignition.•Ammonium dinitramide.•Green aqueous monopropellant.•Hydrazine replacement.