Abstract
HEGPs (High energetic green propellants), the liquid monopropellants based on energetic ionic liquid including Hydroxyl ammonium nitrate (HAN) or Ammonium dinitramide (ADN) are considered promising candidates of alternatives to conventional hydrazine. Yet, insufficient atomization due to the high viscosity of the HEGPs causes a lack of thruster performance, and many parts of the atomization mechanism of the green monopropellants, notably the break-up behavior in the initial part of the injection, remain unexplained. This paper conducts a series of injection experiments with green monopropellants in various conditions, following up with a visual investigation of the injected propellant flow behavior. After explaining the methodology of the visual analysis, it reports the influence on the temporal transitions of the injection, depending on the spray characteristics, the effect of the ambient pressure, and the superheat level.
