Steady Test of In-cylinder Air Motion of Engine with LDV

抄録

A laser doppler velocimeter was allied to a steady-flow test rig to analyze the transition of an intake swirl and a turbulence in a cylinder of a D.I. diesel engine. Three dimensional mean velocity and turbulence were measured with two kinds of intake ports that showed different engine performance. The formation process of the swirling flow in a cylinder was revealed by investigating the angular momentum flux around the intake valve and around the cylinder axis. The transition of the swirl and the turbulence along the cylinder axis showed a remarkable difference between these two ports. From the correlation with engine performance, it was found that the in-cylinder flow near the cylinder head (up to 0.6 ∼0.7 x bore) had more important effect on the engine performance than the swirling flow the swirling flow in the downstream region (1 ∼2 x bore apart from the cylinder head, swirl detectors are often placed).