小型风冷柴油机镶块双通道倾角对涡流特性的影响

Influence on Swirl Feature by the Obliquity Angle of Two-channel Insert Block of Small-scale Air-cooled Diesel Engine

为分析风冷柴油机镶块双通道安装位置对涡流室内涡流形态的影响,以BH175F柴油机为例,基于FLUENT流体仿真软件,研究活塞从曲轴转角210°CA运动至上止点(TDC)时双通道倾角对柱形平底涡流室内涡流特性变化规律.模拟结果表明,镶块双通道倾角对涡流室内涡流形态发展具有重要影响,在设计的30°、40°、45°及50°四种通道倾角方案中,涡流室内涡流发展过程较为相似,均在连接通道左侧形成自由涡,随着曲轴转角的增大,涡流强度增大,涡核上移并稳定在O点位置附近;相对30°、45°通道倾角而言,40°、50°对应的涡流形态发展较快,且在喷油始点附近位置,45°通道倾角所获得的涡流形态更稳定、矢量速度和涡流尺度更大,有利于提高油气混合质量.

In order to obtain the influence of the two-channel insert installation site of air-cooled diesel engine on the vortex development,taken BH175F diesel engine as an example ,the influence of the installed angle of the two-channel insert on pillar fiat swirl chamber flow field is studied when the piston moving from 210~ crank angle （CA） to the top dead center （TDC） on the basis of FLUENT fluid simulation software. The simulation result shows that the obliquity angle of two-channel insert block has a great in-fluence on the vortex development. Among the four designed schemes respectively based on 30~ ,40~ ,45~ and 50~ channel angles, the vortex development in the chamber are very alike which all formed a free vortex on the left side of the connecting channel, and the vortex intensity increases with crank angle enlarging,and the vortex core moves up and stabilizes around the 0 point. However, the vortex development of 30~ and 45~ channel angle is faster than that of 40~ and 50~, and the vortex pattern of 45 ~ channel angle is much stable and has larger vector speed and vortex scale around the oil-inject starting point which are very helpful to improve air -fuel mixture quality.