“…Moreover, intake flow characteristics are affected by different shapes of the intake port structure, port position in the cylinder head, and the combination patterns of the two ports. Therefore, in order to develop high efficiency and low emissions four-valve DI diesel engines, it is important to systematically study the effects of different combinations of intake ports on intake flow characteristics (Kawaguchi at al .,2009, Andreatta et al,2008, Li Yufeng at al .,2001, Li Yufeng and Wang Zhong,2004,Lu Z. et al,2014,and Cui L.et al,2015.…”