Coal-to-liquid (CTL) fuel is considered a promising alternative
fuel for diesel engine applications in China owing to its excellent
fuel properties. However, little research on the spray and combustion
processes of CTL fuel has been scarce. Therefore, in this study, the
spray and combustion characteristics of diesel fuel blends with different
CTL fuel blending ratios were investigated in a constant-volume combustion
chamber. The results show that under non-evaporation conditions (300
K), a longer spray tip penetration (STP) and enlarged spray cone angle
(SCA) were obtained with a higher injection pressure owing to the
enhanced turbulent interaction. The SCA of CTL fuel blending was larger
than that of diesel fuel owing to its lower viscosity and slightly
shorter STP. Under the evaporation condition (700 K), with an increase
in the CTL mixing ratio, both the STP and SCA of the fuel exhibited
a decreasing trend owing to the higher volatility. Meanwhile, as the
CTL mixing ratio increased, the ignition delay period was shortened,
and the flame lift-off length decreased, whereas both the integrated
natural flame luminosity and combustion duration increased. The cetane
number of CTL fuel plays an important role in the occurrence of these
results.