柴油机螺旋进气道直流段的正交优化设计

Orthogonal Optimization Design of Direct Current Section of Diesel Engine Helical Intake Port

通过构建YN33柴油机气道-气门-燃烧室计算流体动力学(Computational fluid dynamics,CFD)模型,以涡流比和进气量作为评价指标,对柴油机螺旋进气道直流段的直流段上偏角、直流段下偏角、直流段长度这3个关键结构参数进行正交优化设计。结果表明:直流段长度对缸内涡流比、进气量的影响最大;直流段上偏角、直流段下偏角及直流段长度3个参数,分别取值82°、85°和69 mm时,可使缸内涡流比和进气量相对原机分别提高26.02%与5.50%;在此条件下,放热率峰值和累积放热量与原机相比分别增加了4.92%和8.29%。

Based on the computational fluid dynamics(CFD)model for YN33 diesel engine,three key structural parameters of helical intake port direct current(DC)section are optimized by using the orthogonal optimization design.Those three parameters are the upper deflection angle of DC section,the lower deflection angle of DC section and the length of DC section.In addition,swirl ratio and air input are used as evaluation indexes.The results show that the length of the DC section has the greatest influence on the swirl ratio and air input.When the upper deflection angle of the DC section,the lower deflection angle of the DC section and the length of the DC section are 82°,85°and 69 mm,respectively,the in-cylinder swirl ratio and intake air volume can be increased by 26.02%and 5.50%,respectively,comparing with the original machine.Under the present condition,the peak heat release rate and accumulated heat release increased by 4.92%and 8.29%respectively comparing with the original machine.