Analysis of Combusting High-Pressure Monopropellant Sprays

摘要

Combusting monopropellant sprays have applications for throttable thrustors, underwater propulsion systems, and regenerative liquid-propellant guns. Monopropellant spray flames are also an important fundamental problem of combustion science, as the premixed counterpart of the spray diffusion flame. Motivated by these considerations, the structure of combusting monopropellant sprays was examined during the present investigation. A simplified analysis of monopropellant spray combustion was developed, based on the locally-homogeneous-flow approximation of multiphase flow theory and the thin-flame approximation of turbulent premixed flame theory. The performance of the analysis was evaluated using shadowgraphs of spray flames for a hydroxyl ammonium nitrate(HAN)-based liquid monopropellant at ambient pressures of 6-8 MPa. Predictions showed that these spray flames are very sensitive to the degree of flow development at the injector exit, with fully-developed turbulent flows requiring significantly smaller combustion volumes than slug flows having low initial turbulence levels. There was encouraging agreement between predictions and measurements; however, uncertainties concerning injector exit conditions for the experiments precluded definitive assessment of the analysis. Reprints. (aw)