Improvement of Flash Atomization Characteristics of HAN-based Green Propellants Using High Saturation Vapor Pressure Additive

抄録

To replace hydrazine, a toxic monopropellant for spacecraft Reaction control system (RCS), the development of less toxic green propellant is vitalizing all over the world. A hopeful candidate for the propellant is SHP163. SHP163 is a mixture of 6.2 wt% water, 16.3 wt% methanol, 3.9 wt% ammonium nitrate, and 73.6 wt% hydroxylammonium nitrate (HAN). One critical issue of green monopropellants is their poor ignitability. It is required to atomize green propellants and enhance their thermal/catalytic ignitability. However, SHP163 is more viscous than hydrazine and hard to atomize by the conventional method. To solve this issue, this study focuses on the atomization of SHP163 by flash atomization. The previous study reported that adding high saturation vapor pressure material is effective in achieving a better flash atomization behavior. Thus, this study attempted to improve flash atomization characteristics of SHP163 by high saturation vapor pressure additive. Acetone was employed as an additive because it has high saturation vapor pressure, is low cost, and is widely used in industry. Injection experiments in atmospheric and low-pressure conditions were carried out and the results are discussed to reveal the predominant factor of propellant atomization in various ambient pressures and evaluate the feasibility of improving the flash atomization characteristics of SHP163 by adding acetone.