Effects of V-type intersecting hole on the internal and near field flow dynamics of pressure atomizer nozzles

Abstract

The coalescence of a pair of sub-holes forms a V-type intersecting hole for pressure atomizer nozzles. This design makes use of the internal impact effect to promote the breakup of liquid jets, enhancing liquid-gas mixing. To clarify the physical structure of the in- and near nozzle flow field for the V-type intersecting hole atomizer nozzles, high speed photography was employed to visualize the in-orifice and near field flow behaviors of four atomizer nozzles, three of which were V-type intersecting hole nozzles with impact angle varied from 30° to 50°, and the other one was a cylindrical hole nozzle as a reference. In-nozzle flow and jet images in both the intersecting plane and its axial normal plane were captured. The results show that the use of V-type intersecting holes in an atomizer nozzle eliminates the generation of cavitation inside the nozzle orifices even under the conditions of strong hydraulic flip for the reference nozzle, leading to 15%–50% higher discharge coefficients than those of the reference nozzle, and yields fan-shaped jets, which least and most disperse at the intersecting plane and its axial normal plane, respectively. Furthermore, these fan-shaped jets demonstrate superior radial dispersion, in terms of 1–5 times larger normalized cross sectional areas than those of the reference nozzle. Moreover, increasing the impact angle enhances the internal impact effect, resulting in wider spreading angles and larger cross sectional areas of the jets, however, lower discharge coefficients.