Effects of in-nozzle flow and low-pressure zone on spray targeting of multi-hole gasoline direct injection injector

Abstract

The purpose of this study is to reveal the effect of In-nozzle flow and low-pressure zone near the nozzle exit on the spray targeting of a multi-hole gasoline direct injection injector using a numerical simulation. The change in spray targeting owing to in-nozzle flow and the distribution of the liquid phase at the hole exit were analyzed through a multi-phase flow simulation. A volume of fluid (VOF) model was used to effectively distinguish between the liquid flow and cavitation region. Results of the numerical simulation at the internal and near-field show that cavitation occurred at a sharp corner with a high flow velocity. Moreover, the low liquid rebounded at the hole wall, and the flow was bent in the direction of cavitation. The results of the spray simulation indicated that an increase in the injection pressure reduced the minimum pressure in the low-pressure zone. By contrast, the increase in ambient pressure not only decreased the pressure in the low-pressure zone, but also caused the low-pressure zone to form closer to the hole exit. In most cases, the low-pressure zone had a greater effect on plume bending than on in-nozzle flow, which was further enhanced as the ambient pressure increased.