Experimental study on the internal flow field and spray characteristics of hollow nozzle

In this paper, the internal flow field and atomization mechanism of a hollow nozzle under different inlet pressures were experimentally studied. The 3D print technology was used to develop a transparent hollow nozzle for visualization research. Variations in the spray cone angle, flow rate and radial spray density were also obtained under different working conditions. The results show that with the increase of inlet pressure, the growth rate of flow rate tends to be slower, and the air flow field in the nozzle swirl chamber is squeezed but with a more stable shape. In addition, the atomization is caused by the broken liquid film at the nozzle outlet. Furthermore, the spray cone angle was determined by the angle of the divergent section at the nozzle outlet under normal operating conditions, and the spray of the hollow nozzle exhibit a regular shape of annulus. As the inlet pressure increases, the effective spray area extends to the center as a whole, and the peak value of spray density also increases obviously. The effect of the increasing spray height is contradictory to that of increasing inlet pressure.