Numerical investigation of pressure oscillation effects on dynamic spray characteristics in kerosene impinging-jet atomization

This study investigates the dynamic atomization characteristics of kerosene impinging jets under high-pressure conditions using a coupled Eulerian–Eulerian and Eulerian–Lagrangian framework. By systematically analyzing the effects of injector pressure differences and inlet/outlet pressure oscillations, the research provides critical insights into spray dynamics and combustion stability. Results indicate that increasing the pressure difference shortens liquid sheet breakup length and suppresses droplet mass flow rate fluctuations. Pressure oscillations induce periodic deformations in the liquid sheet, altering the spray's overall structure. Voronoi tessellation analysis reveals distinct droplet clustering patterns in the impinging-jet spray, suggesting vortex-driven modulation of the spray field. Detailed visualization and analysis of the temporospatial distribution of mass flow rate density and droplet size during primary atomization show that mass flow rate density peaks in the central region and diminishes toward the periphery, while droplet size distribution follows an inverse trend. The Sauter mean diameter (SMD) exhibits non-monotonic axial variation with pressure differences. Under inlet/outlet pressure oscillations, SMD decreases rapidly downstream, with the reduction rate positively correlated to oscillation amplitude. Notably, SMD fluctuations under pressure oscillations significantly exceed those induced by pressure differences. Furthermore, inlet/outlet pressure oscillations generally reduce SMD, though SMD variability increases with oscillation amplitude. Time-lag analysis reveals substantial phase delays between pressure oscillation and atomization parameters: the mass flow rate oscillations of injectors and generated droplets exhibit a half-period delay, while the delay between injector mass flow rate and droplet SMD oscillations extends to a full period. These findings advance injector design optimization and stability prediction in liquid rocket engines by elucidating the atomization process's dependence on operational parameters under realistic combustion chamber conditions.