Air Motion and Its Effect on Diesel Performance and Emissions

Conventional instrumentation, a laser doppler velocimeter and a constant temperature hot wire anemometer were used to characterise the air flow produced by a number of inlet ports typical of those used in open chamber diesel engines. In particular, directed and helical ports were included. The same ports were fitted to a motored single cylinder engine and the air motion characteristics were mapped over the speed range of the engine within the bowl and within the cylinder throughout the engine operating cycle. A comparison of the measured results from the motored engine tests and predictions based upon the steady flow results using conventional instrumentation was made. Performance tests with a single cylinder engine fitted with the same ports were carried out to determine whether or not the induction system influenced the performance of the engine in the way it generated bulk swirl or by any other property of air motion.