Correlation analysis of entropy production and vorticity characteristics of pressure swirl nozzles

Interactions among characteristic vortices in pressure swirl nozzles lead to significant energy dissipation. This study focused on entropy-driven energy loss and the identification of coherent vortical structures and established a quantitative framework linking rigid vorticity transport to entropy production. Based on this framework, the spatial correlations between hydraulic loss and four sub-components of rigid vorticity transport strength were analyzed to identify the dominant mechanisms through which coherent vortices induce localized energy dissipation. The results revealed that turbulent dissipative entropy production predominated in the overall hydraulic loss of pressure swirl nozzles. Direct dissipative entropy production was primarily governed by shear enstrophy. In contrast, turbulent dissipative entropy production showed strong correlations with both total vorticity transport strength and shear enstrophy, but both turbulent and direct dissipative entropy production had weak correlations with rigid enstrophy. Further decomposition of the rigid vorticity transport revealed that direct dissipative entropy production was closely associated with the pseudo-Lamb term, whereas turbulent dissipative entropy production was largely driven by the viscous term and exhibited minimal dependence on the pseudo-Lamb term. Additionally, both shear and total vorticity transport strength were dominated by the pseudo-Lamb mechanism, while shear vorticity transport was mainly influenced by viscous effects. These findings deepened the understanding of energy dissipation and vortex transport dynamics in pressure swirl nozzles, offering new insights for performance optimization and flow control.