Direct injection
gasoline engines have been developed by several
manufacturers for improvement of the fuel economy
and exhaust emissions. These direct injection gasoline
engines utilize air motion such as swirl or tumble
to lead the mixture to the spark plug. However,
the suction port generating the swirl or tumble
sometimes produces a lower volumetric efficiency
compared to the straight port. Therefore, a new
combustion concept, which does not depend on air
charge motion, was proposed. A slit nozzle was developed
to realize this new concept. The nozzle has a rectangular
orifice and forms a thin fan-shaped spray. The spray
characteristics of the slit nozzle were evaluated
and compared to that of the swirl nozzle. The following
results were obtained from the experimental analysis.
(1) The spray penetration increases with increasing
slit thickness. (2) The effect of the slit thickness
on the spray drop size is small at the higher injection
pressures. (3) The features of the slit nozzle include
a high spray penetration, wide diffusion spray and
fine atomization compared to the swirl nozzle.
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