柴油—生物柴油混合燃料喷雾特性试验研究

采用高分辨率数码照相机对柴油与柴油—生物柴油混合燃料喷雾特性进行了对比研究。结果表明,随着生物柴油掺混比的增大,燃料黏度增大,喷雾锥角变小,Sauter平均直径增大。与MB24相比,柴油的相对尺寸范围和发散边界较大,因此其Sauter平均直径比MB24混合燃料的略大。由于乙醇的稀释作用,改制油MB24的Sauter平均直径最小,雾化质量明显改善。从喷雾液滴尺寸的数目分布可以看出,所有燃料的曲线峰值均位于14μm处,小颗粒液滴较多。随着生物柴油掺混比的增大,曲线峰值下降,下降趋势均匀平缓,说明燃料黏度的增大将使雾化油滴的尺寸分布渐趋均匀。从液滴尺寸的累积体积分布可以看出,随着生物柴油掺混比的增大,达到某一累积体积的油滴直径增大,说明大颗粒油滴增多。

Experimental Study on Spray Characteristics of Diesel-biodiesel Blend Fuel

The comparison of spray characteristic between diesel and diesel-biodiesel blend fuel was made by using high resolving power digital camera.The results showed that,with the increase of biodiesel mixed ratio,the fuel viscosity was increased,the spray angle was decreased,and the Sauter mean diameter was increased.Sauter mean diameter of pure diesel was slightly larger than that of MB24 because of pure diesel's larger relative size range and dispersion boundary.Sauter mean diameter of MB24 was the smallest because it was diluted by ethanol,and so spray quality of MB24 was improved evidently.It could be seen by the droplet size number distribution that all fuel curve peaks were located at 14,that was to say,the smaller size droplet took a large percentage.All the curve peaks of droplet size number distribution went down evenly and gently with the increase of biodiesel mixing ratio,which indicated that the fuel droplet size number distribution in spray became even with the increase of fuel viscosity.The diameter of the droplet that reached a certain cumulative volume increased with the increase of biodiesel mixing ration,which indicated that the number of larger drops increased.