バルブリフト量がシリンダ内タンブル流に与える影響の数値解析

抄録

The performance of an automobile engine is affected by the shape of combustion chamber and intake/exhaust system. In particular, flows in a cylinder are affected by the shape of the intake/exhaust pipes and the valve timing. The swirling flows generated in the intake stroke affects combustion speed and combustion stability. In this study, we focused on the tumble flows and performed numerical simulations by modeling piston-cylinder section of a four-stroke engine. The flows in a cylinder were considered by using compressible Euler equations. The virtual flux method was used to express the shape of the engine on a Cartesian grid. Effects of the valve lift on the tumble flows were investigated by using the tumble ratio. As a results, the tumble flows increased because both tumble ratio and turbulence intensity increased when the valve lift was small.