Study on spray characteristics of diesel engine fuel under different ambient temperatures

The spray behavior of diesel fuel under high-temperature conditions plays a critical role in combustion efficiency and emission control. In this study, a constant volume bomb test system was employed to visualize and analyze the spray development of four diesel fuels at ambient temperatures of 423 K, 523 K, and 623 K, under a fixed back pressure of 1.5 MPa and rail pressure of 70 MPa. The results indicate that both the liquefaction and gasification cone angles generally show a decreasing trend before reaching the maximum temperature setting. Meanwhile, penetration distance consistently increases across the temperature range. These patterns imply that moderate heating enhances atomization and accelerates phase transition, while excessive thermal input may destabilize the spray structure. The findings offer practical guidance for optimizing fuel injection strategies in thermally demanding environments.