Combustion Characteristics of an Ammonium-Dinitramide-Based Ionic Liquid Propellant

Abstract

As a replacement for hydrazine, ammonium-dinitramide-based ionic liquid propellant (ADN-based ILP) has been developed by JAXA and Carlit Holdings Co., Ltd. This propellant is made by mixing three solid powers: ADN, monomethylamine nitrate, and urea. The propellant's theoretical specific impulse is 1.2 times higher than that of hydrazine, and its density is 1.5 times higher at a certain composition. Although ionic liquids were believed to be non-flammable for a long time owing to their low-volatility, recently combustible ILs have been reported. The combustion mechanism of ILs is not yet understood. The objective of this paper is to understand the combustion wave structure of ADN-based ILP. The temperature distribution of the combustion wave in a strand burner test shows a region of constant temperature. This region would indicate boiling in a gas-liquid phase. Thus, the combustion wave structure consists of liquid, gas-liquid, and gas phases. The dependence of boiling point on pressure would identify chemical substances in the gas-liquid phase. The dependence of combustion and ignition characteristics on ADN content is also discussed.

Characterization of Continuous‐Wave Laser Heating Ignition of Ammonium Dinitramide‐Based Ionic Liquids with Carbon Fibers

“…The inefficient heating of AMU631 at I CW = 5.70 W was explained considering the condensed phase reactions of highly energetic materials (HEMs) such as hydroxylammonium nitrate (HAN) and ADN [10][11][12][13][14][15].…”

“…Fujisato et al clarified that the decomposition of ADN and the dissociation of AN proceed on the condensed phase of ADN combustion to generate bubbles of gaseous decomposition products [13]. For ADN-EILPs, bubbles were observed on the combustion surface during strand burner tests [14,15]. Previous studies implied that thermal decomposition of AMU631 can generate bubbles on the condensed phase.…”

Continuous‐Wave Laser Ignition of Non‐Solvent Ionic Liquids Based on High Energetic Salts with Carbon Additives

“…Therefore, the first temperature increase in Sample1 seems to be the exothermic decomposition of ADN. Regarding the flat temperature zone at approximately 610 K, such a temperature profile was also experimentally observed by Ide et al [51]. Ide et al carried out strand-burner tests of ADN-EILPs for several pressure conditions [25].…”

Ignition of the Droplets of Ammonium Dinitramide-Based High-Energy Ionic Liquid

“…These results, indicate that the main cause of the start of ADN-based EIL combustion is the ignition of methyl nitrate generated by the reaction associated with ADN and MMAN. Because flame temperature with stable combustion of ADN-based EILs has been reported at approximately 1700 K, 15) methyl nitrate gas generated from the condensed-phase reaction of ADN and MMAN is presumed to ignite first, followed by the ignition of other gases by the heat from the flame.…”

“…Consequently, we have been investigating these mixtures as energetic ionic liquid propellants (EILPs). [10][11][12][15][16][17] The use of ADN-based EILPs in spacecraft necessitates the development of a specialized ignition system because of their unique properties. Because energetic ionic liquids (EILs) comprise only fuel and an oxidizer (without a solvent), the combustion temperature is presumed to be very high.…”