柴油机近气缸盖壁面气流速度和热边界层的研究

An Investigation of Thermal and Gas Speed Boundary Layer Near Cylinder Heat Wall in Diesel Engine

研究了倒拖工况下直喷式柴油机气缸盖近壁气流速度场的分布规律，并利用一维传热模型计算了气缸盖近壁的热边界居，得出了气缸盖近壁不同位置的气流速度和热边界层是不同的，速度边界层基本上在压缩中期形成并达到一定厚度，以及热边界层和速度边界层数量级相同等结论。

Examination of velocity field of the gas flow near the head wall and calculation of its thermal boundary layer in a motored DI diesel engine reveal that the local flow velocity and thermal boundary layer at various location near the head wall are different, the velocity boundary layer occurs generally in midcompression stroke and gradually reaches a certain thickness, and the thermal and the velocity boundary layers are the same in order of magnitude.