Tumbling flow in loop-scavenged two-stroke engines

Yeng-Yung Tsui, Hong Ping Cheng

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


A multidimensional calculation procedure is used to investigate the flow in loopscavenged two-stroke engine with curved cylinder heads. Five different cylinder heads are considered. The curvature of cylinder head increases from case I to case IV. In case V the head curvature is further increased, but it is shaped in the radially outer region. Calculations reveal that a tumbling vortex forms after the exhaust port is closed and the vortex constantly dominates the flow structure in the cylinder throughout the compression period. With high head curvatures the vortex is well organized and occupies the entire cylinder volume in the late compression stage. Due to compression of the better organized tumbling vortex by the moving piston more energy cascades from mean flow to turbulence in the high curvature cases III and IV. As for case V, the larger clearance in the bowl center region leads to lower shear stresses and, thus, the turbulence augmentation phenomenon is less prominent than that for cases III and IV.

Original languageEnglish
Pages (from-to)628-632
Number of pages5
JournalJournal of Fluids Engineering, Transactions of the ASME
Issue number4
StatePublished - 1 Jan 1995

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