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.
|Title of host publication||Book of abstracts. EUROMECH Colloquium 525: Instabilities and transition in three-dimensional flows with rotation|
|Number of pages||2|
|Publication status||Published - 2011|
|Event||EUROMECH Colloquium 525 - Instabilities and transition in three-dimensional flows with rotation - Ecully, France|
Duration: 21 Jun 2011 → 23 Jun 2011
|Conference||EUROMECH Colloquium 525 - Instabilities and transition in three-dimensional flows with rotation|
|Period||21/06/2011 → 23/06/2011|