Tumbling Flow in Loop-Scavenged Two-Stroke Engines

[+] Author and Article Information
Yeng-Yung Tsui, Hong-Ping Cheng

Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan

J. Fluids Eng 117(4), 628-632 (Dec 01, 1995) (5 pages) doi:10.1115/1.2817314 History: Received July 08, 1994; Revised April 12, 1995; Online December 04, 2007


A multidimensional calculation procedure is used to investigate the flow in loop-scavenged 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.

Copyright © 1995 by The American Society of Mechanical Engineers
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