Numerical simulation of valved intake port and in-cylinder flows using KIVA3

The KIVA3 code was modified to simulate intake flows incorporating moving valves and real geometries. The intake and compression strokes of a four valve, four stroke, single cylinder diesel engine were modeled. Unsteady, turbulent, three dimensional calculations were solved.;Mass flow rate and fuel injection flow field in-cylinder pressure compared well with experimental values, agreeing within 1.0% and 8.5% respectively. Lack of a blowby model in the present computations and uncertainty in the engine compression ratio could explain some of these differences. Mass flow rates differed between both intake valves affecting, in-cylinder flow patterns throughout intake and compression.;Early in the intake stroke, little in-cylinder mixing occurs between air entering from the different valve regions. Swirl near the head during intake had no noticeable trend. Near the piston, swirl increased steadily in the direction governed by the higher mass flow valve.;High speed jets entering the cylinder and accelerating downward piston motion generated turbulence in the first part of the intake stroke. In-cylinder turbulence fell as the piston decelerated. Axial velocity variations correlated with intake stroke turbulence generation. Variations in swirl had no noticeable correlation.;During compression, the opposite was observed. Axial velocity data showed no relation to turbulence data. A relation was evident for swirl and turbulence, as swirl patterns were disrupted by the intrusion of the Mexican hat style bowl during compression.;A comparison of an intake generated flow field to a flow field initiated by assuming an axial velocity profile varying linearly from the piston to the head, solid body swirl and uniform in-cylinder properties was made. The intake generated, fuel injection flow field had twice the turbulent kinetic energy and half the in-bowl swirl compared to the assumed flow field case. The linearly varying axial velocity looks to be a valid approximation. In-cylinder swirl profiles being much more complex than simple rotating flows is believed to be the reason for the above noted differences.