进气滚流强度对直喷发动机燃烧特性的影响

以光学单缸直喷汽油发动机作为试验平台,通过在进气法兰处安装不同的滚流导流板调节进气截面积来获得不同强度的滚流气流。利用Converge软件对缸内滚流强度和湍动能进行评估,采用高速彩色相机拍摄不同滚流强度下火焰状态随曲轴转角的变化,同时采用燃烧分析仪采集缸压数据。通过图像处理分离蓝色火焰和黄色火焰,其中,蓝光被认为主要来自火焰中CH释放的化学荧光,而黄光被认为主要来自炭烟颗粒的辐射。试验发现:随着滚流强度的提高,蓝色火焰面积增加,缸内燃烧速率得以提升,缸内平均指示有效压力增强,相关性分析表明,蓝色火焰面积和燃烧放热率有很好的正相关性。同时,黄色火焰随滚流强度增加而减少,表明炭烟生成量降低。此外,燃烧的循环波动也随滚流强度的增加而降低。

Effects of Intake Tumble Strength on Combustion Performance in SIDI Engine

Variable tumble ratios were achieved by adjusting the cross-section area of intake manifold with different flow guide plates on a SIDI optical engine test bench.In-cylinder tumble strength and kinetic energy were evaluated with Converge software,the crank angle resolved flame images were recorded with a high speed color camera and the instantaneous cylinder pressure was monitored by a combustion analyzer.The blue and yellow flames were separated with the image processing,which represented the CH released chemiluminescence and the soot particle radiation respectively.The results show that with the increase of the tumble strength,the blue flame area,burning rate and IMEP all increase.It shows a strong correlation between the blue flame area and the heat release rate.Meanwhile,it is indicated the soot reduces because the yellow flame decrease.Besides,higher tumble ratio can suppress cycle-to-cycle variation.