Air flow effects in the piston ring pack and their implications on oil transport
Name
825074427-MIT.pdf
Description
Full printable version
Size
11.58 MB
Format
Adobe PDF
Checksum (MD5)
976a34fd87a3cf92239e36342fd2e0f6
Author(s)
Wang, Yuan, S.M. Massachusetts Institute of Technology
Advisor(s)
Tian Tian.
Date Issued
2012
Publisher
Massachusetts Institute of Technology
Abstract
3 different flow regimes of piston blowby air and their influences on oil transport are studied. It is found that air mainly interacts with oil close to the ring gaps and directly below the ring-liner contacts. Geometric features at the gaps to smoothen airflow and prevent flow detachments can increase blowby mass flow rate and thus drainage oil mass flow rate by up to 60%. Only oil within 1 to 2 gap widths distance from the gaps are transported through the gap by air drag and the engine pressure drop. Downstream of the ring gap, transported oil will either be caught in vortices directly below the ring gaps or pumped into the downstream ring groove due to the creation of a blowby stagnation point. Far away from the gaps, oil is mainly transported in axial direction through the grooves and the piston-liner interface. Low capillary numbers in the order of 10-5 indicate close to no oil transport into circumferential direction from blowby shear. The oil transport radially into the grooves is mainly determined by hydrostatics and capillary effects in the groove flanks whereas air in the second land only has an influence on oil transport by preventing bridging after TDC by creating a stagnation point directly below the rings on the liner.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012.
This thesis was scanned as part of an electronic thesis pilot project.
Cataloged from PDF version of thesis. This thesis was scanned as part of an electronic thesis pilot project.
Includes bibliographical references (p. 85).
Subjects
Aeronautics and Astronautics.
MIT Department
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics
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