Technical Paper
Assessment of the Time Step in the Modeling of Cold Flow in a Motored Diesel Engine
2010-10-06
2010-36-0090
The work investigates the effects of the time step in the modeling of the intake and in-cylinder systems of a diesel engine, under the motored condition. The engine has a bore of 79.5 mm and a stroke of 86 mm. The valves and piston movements are included. The equations are numerically solved, including a transient analysis of the intake stroke, for an engine speed of 1500 rpm, using a commercial Finite Volumes CFD code. For the purpose of examining the in-cylinder turbulence characteristics two parameters are observed: the discharge coefficient and swirl ratio. Regarding the turbulence, computations are performed with the Reynolds-Averaged Navier-Stokes, Eddy Viscosity Model k-ω SST, and also the k-ε standard cubic model (usual in the automotive industry), with standard near wall treatment. A moving hexahedral mesh independence study is presented. In the same way many convergence tests are performed, and a secure criterion established.
