四气门直喷式柴油机缸内流场试验研究

通过螺旋气道与不同进口面积切向气道的组合试验，分析了各种组合进气系统的流通特性，发现通过改变切向气道进口面积就能很容易地实现涡流比的调节。利用热线风速仪对模拟缸内空气流动进行了测量，结果表明4气门柴油机进气过程中在远离缸盖的平面内形成稳定的旋涡，其涡流中心偏离气缸中心。揭示了4气门柴油机进气涡流的形成过程及缸内流场的特点，详细探讨了切向气道进口面积和气门升程对缸内流场的影响。

Experimental Study of Flow Field in Cylinder of a 4-valve D.I. Diesel Engine

Experiments on the twin inlet ports, which are combined separately by helical port and tangential port with different inlet area, are carried out. The flow characteristics of inlet system with multifarious combinations are analyzed. It indicates that the swirl ratio adjustment can be simply actuated by altering tangential port inlet area. Hot wire anemometer is applied to test the air flowing in model cylinder. Results present that in the plane apart from the bottom of cylinder head the relative steady swirl is perceived and it's center deviates from the cylinder center. In cylinder of the 4 valve D.I. diesel engine the formation of intake swirl and characteristics of the flow field during charging process are discovered. Otherwise, the impacts of tangential port inlet area and valve lift on the flow field in cylinder are explored.