Keiichi Hori

Space Transportation Symposium FY2020 (January 14-15, 2021. Online Meeting)

平成25年度宇宙輸送シンポジウム（2014年1月16日-17日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県資料番号: SA6000016009レポート番号: STCP-2013-009

平成25年度宇宙輸送シンポジウム（2014年1月16日-17日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県資料番号: SA6000016010レポート番号: STCP-2013-010

The cost reduction is currently important for the development of space launch systems. The solid motor side jet system is loaded the low temperature gas generator propellant (GGP) which includes a special purpose material. The combustion gas temperature of GGP should be controlled up to 1400 K because of the system requirement. The objective of this research is to find the substitution of the composition for GGP to reduce the cost. That is why ammonium nitrate (AN) is selected as an oxidizer for GGP. The composition and combustion characteristics of AN based GGP for the launch vehicle side jet system were investigated. The burning rate was measured by the strand burner.

Combustion characteristics of pelletized ammonium dinitramide (ADN) and ADN-based propellants have been studied. Micron-meter-sized particles of Al, Fe2O3, TiO2, NiO, Cu(OH)NO3, Cu and CuO, and nano-meter-sized Al (Alex) and CuO (nanoCuO) were employed as the additives for pelletized ADN. Only nanoCuO and Alex show the remarkable effects, so they are also added to ADN-based propellant. The binder of ADN-based propellant is thermoplastic elastomer (TP), and three kinds of mixtures (TP:ADN = 30:70, 20:80 and 10:90 mass%) were prepared .The burning rates of pelletized ADN and ADN-based propellants were measured under the pressure range from 0.6 to 6.2 MPa, and the surface temperature profiles were obtained about ADN-based propellants. Nano-sized CuO enhanced the burning rate of pelletized ADN. Alex-incorporated ADN burned with flames even at 0.55 MPa under which pure ADN does not form the flame. Burning rate of non-additive ADN-based propellants has extremely high pressure dependency. In the case of TP/ADN (30:70), burning rate jump are found from the critical pressure approximately 3.2MPa. The temperature profiles of TP/ADN (30:70) were measured, and the combustion structure was discussed. Both nanoCuO and Alex improved the burning rate characteristics, and the pressure exponents are 0.54 and 0.76 respectively.

The cost reduction is currently important for the development of space launch systems. The replacement of the special purpose product by the general one is effective for the reduction in cost. The solid motor side jet system is loaded the low temperature gas generator propellant (GGP) which is composed of a special purpose material. The combustion gas temperature of GGP should be controlled up to 1400 K because of the system requirement. That is why ammonium nitrate (AN) is selected as an oxidizer for GGP. The composition and combustion characteristics of AN based GGP for the launch vehicle side jet system were investigated. The gas temperature was previously estimated by calculation and verified directly by the static firing test. This work is the first step for the improved GGP development.

Hydroxylammonium nitrate (HAN) based liquid propellant has been investigated as a candidate for the monopropellant to be utilized in the reaction control system of satellites as an alternative to hydrazine. This propellant, which consists of ammonium nitrate, methanol, and water, has moderate burning characteristics, sufficiently low freezing temperature, high density, low toxicity, and its density x Isp is 70% higher than hydrazine. In a previous study, the combustion characteristics of the propellants were obtained and found to be very complex. In this paper, the research was focused on the combustion characteristics of HAN aqueous solution. Sample solutions of several concentrations, 95-50 mass %, were prepared. The measurement of linear burning rates, the temperature measurement of the combustion wave, and the observation of combustion phenomena were included in the study. The linear burning rate does not increase monotonically with increasing HAN concentration. The burning rates increase as the HAN concentration increases up to 80 mass %, and decrease as the concentration increases from 80 to 95 mass %. The burning rate peaks at around 80 mass % of HAN concentration. The combustion mode is very complex and is dependent upon composition and pressure. Temperature measurements indicate that the role of the two-phase region is very important, and the boiling of water caused by superheat is responsible for the high burning rate. The relationship between the rate of nucleation of bubbles and the linear burning rate is discussed.