New evaluation index for bulk motion of in-cylinder flow through intake port system in cylinder head (II)

Abstract

The variable intake systems recently tend to be adopted in gasoline engines for fuel economy and emission regulation. In the cases, because both swirl and tumble flows are together induced to the cylinder, in-cylinder flow pattern becomes very complicated so that we cannot decide this flow as one major pattern like swirl or tumble. The purpose of this study is to find new evaluation indexes for in-cylinder flow characteristics instead of a current swirl or a tumble ratio at the end of intake stroke using a steady flow test rig. To do this, port flow rig tests were conducted on the DOHC head varying lift of intake valves. Finally, the angular flow parameter PA and the flow angle (φ) were introduced as new evaluation indexes for in-cylinder angular flow characteristics at the end of intake stroke.