In Silico Study of Obstruction-Induced Spray Modulation in Injector Nozzles for Enhanced Atomization

This study presents a computational fluid dynamics (CFD) investigation into the effect of internal obstructions on spray characteristics in injector nozzles, focusing on their role in controlling breakup and shoot-off distances for enhanced atomization. Using Volume of Fluid (VOF) and Discrete Phase Model (DPM) techniques, the multiphase interactions between kerosene and air were simulated under high-turbulence crossflow conditions. An isosceles triangular obstruction was introduced at various positions along the exit duct to modulate exit velocity and droplet dispersion. The simulation results demonstrate that obstructions positioned closer to the nozzle exit significantly increase shoot-off distance (from 475 mm to over 1000 mm) and induce earlier breakup, resulting in finer spray dispersion. In contrast, obstructions placed deeper inside the duct allow partial flow stabilization, yielding narrower spray cones. The CFD model was validated against experimental discharge coefficient data with a maximum error of 1.8%, establishing confidence in the predictive capability of the simulations. These findings suggest that strategically positioned internal obstructions offer a viable approach to fine-tune atomization characteristics without requiring full nozzle redesign, offering potential benefits for aerospace propulsion, combustor design, and fuel-air mixing systems. Further experimental validation is recommended to refine these in silico observations for practical injector optimization.