The Spray Properties of a Swirl Co-Axial Aerated Injector: An Experimental Investigation

An experimental investigation of the spray characteristics of a twin-fluid swirl co-axial aerated injector (SCAI) is reported. The objective is to understand the effect of increasing the gas-to-liquid ratio (GLRm), injection pressure (pi), liquid mass flow rate (mi), and swirl intensity (MR) on atomization. Isothermal measurements employing optical and laser-based techniques are performed with water as the surrogate fuel, air as the aeration fluid, and a co-axial swirl medium. With an increase in GLRm, the spray morphology transitioned from annular to flow-blurring (FB), with notable improvements in atomization and spray dilution. For a fixed mi, the spray cone angle increased with GLRm and pi. Though the spray breakup mechanism remained unchanged with increasing pi, a marginal decrease in SMD and enhanced dilution were evident. The study also revealed a strong correlation of SMD with two-phase flow bulk velocity vm at the nozzle exit when compared to mi or Qa or GLRm alone for a fixed pi. With the investigated configuration of the swirl module, the swirl intensity had only a minimal impact on the twin-fluid spray and atomization characteristics. At higher pi, the influence of MR on the droplet velocities diminishes.