柴油掺混二甲醚喷雾粒子尺寸分布特性试验研究

摘要

In order to determine the improvement of fuel spray property for diesel fuel blended with dimethyl ether (DME) , the size distribution characteristics of spray droplet under different mixing ratios ,injection pressures and orifice diameters were compared and researched with shadow imaging and digital image processing technology .The results show that the curve of size distribution for blended fuel droplet has a deviation to the direction of small droplet with the increase of DME proportion due to the flash boiling effect of DME in diesel fuel .The number of larger size droplets decreases significantly ,which helps to improve soot emission .In addition ,the orifice diameter and injection pressure have great influence on size distribution of spray droplet of blended fuel .The small orifice diameter leads to the smaller fuel droplet ,but the low injection pressure will make spray effect become worse .%为确定二甲醚掺入柴油后对燃料雾化性能的改善效果,利用阴影成像与数字图像处理技术,对不同掺混比、喷射压力以及喷孔直径等条件下的二甲醚-柴油混合燃料喷雾粒子尺寸分布特性进行了对比试验研究.结果发现:由于柴油中二甲醚的闪急沸腾作用,随着二甲醚掺混比的增加,混合燃料粒子尺寸分布曲线整体向小颗粒方向偏移,较大粒子数目较柴油明显减少,有助于降低发动机炭烟排放;喷孔直径、喷射压力等喷射参数对混合燃料雾化粒子分布有较大影响,减小喷孔直径使燃油粒子更加细化,降低喷射压力则使混合燃料雾化效果有变差的趋势.