Numerical analysis of flash-boiling spray characteristics with liquid ammonia

Liquid ammonia is a promising clean fuel, but it has a greater tendency to flash-boil than conventional fuels. This study confirms the reliability of utilizing the Eulerian framework and homogeneous relaxation model for simulating flash-boiling liquid ammonia sprays by comparing the simulation results with experimental data. The characteristics of single-hole superheated liquid ammonia sprays are analyzed for different orifice aspect ratios and superheat degrees. The results indicate that superheat degree and orifice aspect ratio affect the external spray morphology by affecting the two-phase flow inside the orifice. The strong phase transition due to flash-boiling drives the spray expansion process and increases the velocity. Moreover, the extensive bubble breakup in flash-boiling sprays promotes faster atomization. However, flash-boiling also results in a more pronounced temperature drop in the spray zone. This research can provide valuable insights for future simulations and engineering practices involving flash-boiling ammonia sprays.