Influence of piston position on the scavenging and swirling flow in two-stroke Diesel engines

A. Obeidat (1) , S. Haider (1) , K.E. Meyer (1) , T. Schnipper (1) , S. Mayer (2) , J. Walther (1, 3)

1 Department of Mechanical Engineering and Center for Fluid Dynamics
2 MAN Diesel and Turbo
3 Chair of Computational Science

We study the e ect of piston position on the in-cylinder swirling ow in a low speed large two-stroke marine diesel engine model. We are using Large Eddy Simulations in OpenFOAM, with three di erent models for the turbulent ow: a one equation model (OEM), a dynamic one equation model (DOEM) and Ta Phuoc Loc's model (TPLM). The simulated ows are grid-independent and they are computed in situations analogous to two di erent piston positions where the air intake ports are uncovered 100% and 50%, respectively. We nd that the average ow inside the cylinder changes qualitatively with port closure from a Burgers vortex pro le to a solid body rotation while the axial velocity changes from a wake-like pro le to a jet-like pro le. The numerical results are compared with measurements in a similar geometry [3] and we nd a good agreement between simulations and measurements. Furthermore, we consider the unsteady ow and identify a dominant frequency in a power spectrum based on velocity which we show is due to precession of the vortex core, and compare with measurements of the unsteady ow obtained with Laser Doppler Anemometry.

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

A. Obeidat, S. Haider, K.E. Meyer, T. Schnipper, S. Mayer, et al.. Influence of piston position on the scavenging and swirling flow in two-stroke Diesel engines. EUROMECH Colloquium 525 - Instabilities and transition in three-dimensional flows with rotation, Jun 2011, Ecully, France. ⟨hal-00600497⟩