As engine technology developed continuously, engine with both turbocharging and
EGR has been researched due to its benefit on improving the engine efficiency.
Nevertheless, a technical issue has raised up while utilizing both turbocharging
and EGR at the same time: excess condensed water existed in intake manifold
which potentially trigger misfire conditions. In order to investigate the
root-cause, a CFD model (conducted by CONVERGE CFD software) was presented and
studied in this paper which virtually regenerated intake manifold flow-field
with EGR condensed water inside. Based on the simulated results, it concluded
that different initial conditions of EGR condensed water could significantly
change the amount of water which deposited in each cylinder. Thus, a coefficient
of variation of deposited condensed water amount among these cylinders, was
marked as the evaluation reference of cylinder misfire. Theoretically, as this
coefficient of variation reduced, the EGR condensed water from intake manifold
would be distributed homogeneously in each cylinder, and thus less possibility
of cylinder misfire should be observed. As concluded from the presented multiple
simulated results, the coefficient of variation of deposited condensed water
amount was above 30% statically for the existing intake manifold, which meant
the existing intake manifold had tremendous room for optimization. The result
showed that the fluctuation of the inner surface of the intake manifold had a
great impact on the flow of condensate water, so different surface shapes could
be designed in the intake manifold to organize the flow of condensate water, so
as to make the condensate water of each cylinder more uniform, and reduce the
occurrence of fire.