In order to provide the theory and experimental basis for engine operating on the oxygenated fuels

combustion characteristics and emissions of direct injection diesel engine operating on the diesel/ethanol blends were investigated. The results show that the brake specific fuel consumption increases with the increase of ethanol fraction in the blends. However

the diesel equivalent brake specific fuel consumption decreases and the thermal efficiency increases with the increase of ethanol fraction in the blends. In the case of high ethanol fraction in the blends

the addition of the cetane number improver is favorable to the increase of the cetane number of the blends. For the same brake mean effective pressure and fuel delivery advance angle

the exhaust smoke decreases with the increase of ethanol fraction in the blends

while NO

x

shows little variation with the addition of ethanol in the blends. The exhaust smoke reduction rate increases with the increase of the oxygen fraction in the blends. The exhaust

smoke reduction rate of the blended fuels without cetane number improver is lower than that of those with cetane number improver. The exhaust smoke increases and NO

x

decreases with the decrease of the fuel delivery advance angle.