Spray dynamics characteristics in gasoline direct injection injectors at varied orifice inlet angles

The orifice inlet angles play a crucial role in determining the internal flow and cavitation characteristics, such as void fraction and cavitation asymmetry, ultimately affecting the spray plume and droplet diameter distribution characteristics. A simulation investigation was conducted on the coupled internal flow and breakup atomization process using the Eulerian–Lagrangian spray atomization method. The results indicate that nozzles with a symmetrical inlet included angle exhibit a higher symmetry in cavitation distribution within the orifice. As the inlet included angle increases, both the cavitation area and cavitation asymmetry decrease, leading to an increase in the plume direction angle and plume cone angle. The inlet included angle of 90° is a critical point of the liquid core shape changes. The spray plume leans toward the side where the wall inclination angle is below 0°, resulting in a reduced cavitation on this side. Conversely, cavitation enhances on the other side where the wall inclination angle is above 0°, causing the formation of hydraulic flip. Decreasing the wall inclination angle reduces the diameter of all droplets. The maximal diameter of the spray droplet is negatively correlated with cavitation asymmetry, with an optimal value of void fraction of 0.279. A decrease outside-inlet included angle by 30° results in a 15% reduction in the maximal spray droplet diameter, while changing the wall inclination angle by 20° causes a 42% reduction.