The effect of swirl on combustion and exhaust emissions in heavy-duty diesel engines

The effect of in-cylinder air swirl on diesel combustion and exhaust emissions has been studied in a heavy-duty diesel engine. A 1.8 L single-cylinder diesel engine fitted with a device to modify the swirl rate was used. This device allowed variation of the mean swirl ratio, a parameter related to the ratio of the angular velocity of the air within the combustion chamber and crankshaft angular rotation, from 0 to 5.33. Although no single optimum swirl level has been found, the results presented here give an insight into swirl effects on diesel engine combustion and exhaust emissions over a wide range of engine operating conditions.