We study the eect of piston position on the in-cylinder swirling flow in a low speed large two-stroke marine diesel engine model. We are using Large Eddy Simulations in OpenFOAM, with three different models for the turbulent flow: a one equation model (OEM), a dynamic one equation model (DOEM) and Ta Phuoc Loc's model (TPLM). The simulated flows are grid-independent and they are computed in situations analogous to two different piston positions where the air intake ports are uncovered 100% and 50%, respectively. We find that the average flow inside the cylinder changes qualitatively with port closure from a Burgers vortex profile to a solid body rotation while the axial velocity changes from a wake-like profile to a jet-like profile. The numerical results are compared with measurements in a similar geometry  and we find a good agreement between simulations and measurements. Furthermore, we consider the unsteady flow 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 flow obtained with Laser Doppler Anemometry.
Book of Abstracts. Euromech Colloquium 525: Instabilities and Transition in Three-dimensional Flows With Rotation, 2011
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EUROMECH Colloquium 525 - Instabilities and transition in three-dimensional flows with rotation, 2011