堀 恵一

Since 2000, Japan Aerospace Exploration Agency (JAXA) is involved in the research and development (R&D) of hydroxYlammonium nitrate (HAN)-based liquid monopropellant, SHP163 which is composed of HAN, ammonium nitrate (AN), methanol and water for its possible utilization as an alternative of hydrazine toxic component. The freezing point of SHP163 is much lower, the density and the density-Isp are higher than those of hydrazine. The toxicity of SHP163 is also lower than hydrazine, therefore easy handling. Moreover, SHP163 monopropellant showed stable burning rate measured by strand burner and its thermal decomposition of HAN-based occurred in two steps. However, the catalytic process showed a violent exothermic reaction of HAN-based in one step at low temperature onset around 65 C. The application of SHP163 on thruster firing tests showed that pressure slopes have been increased in the case of honeycomb catalysts and burning reactions have been improved by new synthesized Ir-CuO honeycomb catalyst. The obtained results on thruster 20 N type demonstrate that SHP163 is a good candidate as green propellant and proved the reason why it has been selected to be used as hydrazine alternative monopropellant for "Innovative Satellite Technology" project launched in 2016 by JAXA, Japan. (C) 2016 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

HAN-based liquid monopropellant has been studied for its possible substitution of hydrazine toxic component. The onset temperature of decomposition was provided by DTA-TG thermal analysis. Moreover, the effect of 5M HNO3 and 5M NH2OH addition on catalytic decomposition was also examined. The major products measured by mass spectrometer were N2, NO, N2O, NO2, H2O and NH3. Otherwise, the burning rates of HAN-based monopropellants were measured from the strand burner videos taken by high speed camera. The effect of methanol addition; as fuel; on the burning rates was demonstrated. On the other hand, HAN-based liquid monopropellant was tested and decomposed in 20N thruster and different catalysts were compared. Honeycomb catalysts were tested instead Shell 405 catalysts, the obtained data demonstrate the improvement of burning reactions and pressure slopes after HAN-based decomposition.

This paper reports on the thermal and combustion behaviors of ammonium dinitramide (ADN). The thermal behavior is measured by a pressure thermogravimetric analysis (TGA) at pressures below 8MPa. The burning rates of pure ADN and ADN/ammonium nitrate (AN) mixtures are measured in the range 0.2-12MPa, and the burning temperature profiles are obtained using thermocouples with diameters of 5 and 25m. This report mainly focuses on the condensed-phase behavior in the vicinity of a burning surface. The temperature profiles are complicated because the ADN decomposition and AN dissociation compete during the condensed phase, and the bubbles of the decomposition gas and gas-phase flame also affect the surface temperature. AN addition helps to understand the effects of AN during the condensed phase, and it was shown that the burning temperature rises to the critical temperature of AN. Based on these experimental results, the pressure dependency of the burning rates is also discussed.