Electrolytic-induced decomposition and ignition of han-based liquid monopropellants

Experimental results are reported on the ignition characteristics of XM46 liquid propellant at room conditions using electrolysis. The ignition system employed a titanium microfin electrode module, which is comprised of 8 parallel fins evenly spaced with separation distance of 1-mm. Each fin has a dimension of 9 × 19 × 0.25 mm generating a surface area of approximately 350 mm². Input voltage to the electrodes ranged from 7 to 26 VDC and electrode surface area ranged from 1050 to 4200 mm². Experiments were performed in a liquid strand burner in which the propellant ignited, combusted, and propagated downward. The propellant initially bubbled at the surface of the electrodes and then ignited to establish a self-propagating thermal wave. The observed linear burning rates were consistent with extrapolated values of published rates at higher pressures. At one atmosphere, a highly luminous gas-phase flame positioned above the surface of the propellant was not observed. A higher input voltage facilitated the gasification of XM46 while minimizing the total energy required. The time delay to peak power (reactivity) decayed exponentially from 160 seconds to 2-3 seconds with an increase in the input voltage from 7 to 12 VDC. Beyond 12 VDC, the time delay dependency became less significant and appeared to remain constant. Peak power increased from 30 to 550 W when the input voltage was increased from 7 to 15 VDC. The power density decreased with increasing surface area indicating that the power was not linearly dependent on electrode surface area. The propellant liquid temperature reached a nearly steady-state temperature of 115^oC, which agrees with the temperature or pure HAN during thermal decomposition.