Two different geometries of the intake valves on the cylinder head of a fou
r-valve large-bore diesel engine were compared in terms of their swirl gene
ration mechanisms in the cylinder during the intake process. The swirl gene
ration level and flow resistance were measured using a swirl meter on a ste
ady flow rig and the detailed intake flow structure was studied using LDV m
easurements of the in-cylinder bulk flow velocity and turbulence intensity.
The effects of changes in the maximum valve lift were also studied for eac
h type of valve arrangement. Methods for calculating the swirl moment from
the LDV data are presented and discussed by comparing with the swirl meter
results. It was found that the aligned valve port arrangement (valves locat
ed at equal distances from the symmetry axis) generates higher swirl due to
its eccentricity with respect to the intake port. In an inclined valve por
t engine (valves at different distances from the symmetry axis), increasing
the maximum valve Lift was found to improve the swirl generation capabilit
y significantly, even though it generated less swirl overall due to swirl c
ancellation at low valve lifts. (C) 1999 Elsevier Science Inc. All rights r
eserved.