Research on the internal flow and macroscopic characteristics of a diesel fuel injection process

The internal flow and macroscopic spray behaviors of a fuel injection process were studied with schlieren spray techniques and simulations. The injection pressures(P(in))and ambient pressures(P(out))were applied in a wide range. The results showed that increasing the P(in) is likely to decrease the flow performance of the nozzle. Furthermore, increasing the P(in) can increase the spray tip penetration. However, the effect of P(in) on the spray cone angle was not evident. The spray cone angle at an injection pressure of 160MPa was 21.7% greater than at a pressure of 100MPa during the initial spraying stage. Additionally, the discharge coefficient increased under high P(out), and the decrease in P(out) can promote the formation of cavitation. Finally, increasing the P(out) can decrease the penetration, while the spray angle becomes wider, especially at the initial spray stage, and high P(out) will enhance the interaction of the spray and the air, which can enhance the spray quality.