LAUSR

Abstract To better understand the atomization characteristics of a gas–liquid swirl coaxial (GLSC) injector under ambient pressure, the spatial distribution of multiple cross-sections was captured using a phase Doppler interferometry system, including the Sauter mean diameter (SMD), velocity, and data rate (particle number collected at the measurement points every second). The effects of the gas–liquid ratio and ambient pressure on the spatial distribution of the GLSC injector were analyzed. In general, the SMD increased with an increase in ambient pressure, while the axial velocity and data rate showed the opposite trend. For the non-recessed GLSC injector under ambient pressure, the atomization quality at low gas–liquid ratios was not better than that for no gas injection. In the area near the injector exit, the ambient pressure positively affected the atomization. Furthermore, the ambient pressure had a negative effect beyond a certain distance from the injector exit. The effect of environmental pressure on the spray cone was more apparent, and the combined effect of pneumatic and pressure atomization was worse, which eventually increased the particle diameter at the axis center. An increase in the gas–liquid ratio had little effect on the axial velocity around the spray cone but caused a significant increase in the axial velocity near the axis.