Spray Auto-ignition Behaviors of Diesel and Jet Fuel at Reduced Oxygen Environments

Spray auto-ignition behaviors of the RP-3 jet fuel were compared to those of a conventional diesel fuel on a constant-volume combustion chamber. The experiments were conducted at changed ambient temperatures and oxygen concentrations, with adjusted fuel injection pressure and duration as well. Compared to diesel fuel, the RP-3 jet fuel exhibits less auto-ignition propensity and lower burn rate, its ignition delay, and combustion delay times are more sensitive to the change in temperature and oxygen concentration, and more obviously staged heat releases and pressure rises are observed at lower oxygen ambience. Also, the peak heat release rate of diesel fuel exhibits an apparent non-monotonic trend versus increased temperature at high oxygen environments, due to the reduced premixed burn intensity with increased ambient temperature, while this non-monotonic trend for the RP-3 jet fuel is less significant, as the peak burn intensity is less influenced by changed ambient temperature. Finally, both elevated injection pressure and extended injection duration significantly reduce the combustion delay time at lower ambient oxygen concentrations, because the interval between the two-stage pressure rises, that occur at lower ambient oxygen environments, are apparently shortened.

Automated summary

This study compares the spray auto-ignition behaviors of RP-3 jet fuel and conventional diesel fuel. The results show that RP-3 jet fuel has lower auto-ignition propensity and burn rate compared to diesel fuel. The ignition delay and combustion delay times of RP-3 jet fuel are more sensitive to changes in temperature and oxygen concentration. In addition, staged heat releases and pressure rises are more evident in lower oxygen ambience. The peak heat release rate of diesel fuel exhibits a non-monotonic trend with increasing temperature, while this trend is less significant for RP-3 jet fuel. Elevated injection pressure and extended injection duration significantly decrease the combustion delay time at lower ambient oxygen concentrations.