加氢催化生物柴油-柴油的喷雾燃烧特性

Study on Reacting Spray Characteristics of a Blend Fuel with Hydrogenation Catalytic Biodiesel and Diesel

基于装配有单孔喷油器的高温高压定容燃烧弹系统,研究了一种混合燃油(柴油质量分数为80%,加氢催化生物柴油质量分数为20%)的喷雾燃烧特性.此外,针对纯柴油也进行了相同的试验以作为对比.试验采用高速纹影图像技术和OH^(*)化学荧光法两种光学技术同步测量了着火延迟期(ID)和火焰浮起长度(LOL)等参数,通过纹影图像得到了喷雾演化过程以及喷雾贯穿速度.结果表明:混合燃油的ID和LOL均小于纯柴油,这是因为混合燃油有更高的十六烷值;由于燃烧引起局部密度下降,燃烧喷雾的喷雾贯穿速度大于未燃烧喷雾;由于混合燃油具有更高的低热值,混合燃油的喷雾贯穿速度在准稳态阶段高于纯柴油.

Spray characteristics of a blend fuel with 80%diesel and 20%hydrogenated catalytic biodiesel(mass fraction)were studied within a high-pressure,high-temperature constant volume combustion vessel with a single-hole nozzle.Meanwhile,the pure diesel was also tested as a reference fuel.Two optical techniques,high-speed schlieren imaging and OH^(*)chemiluminescence,were performed simultaneously to measure the ignition delay(ID)and flame lift-off length(LOL).Besides,the spray penetration velocity and spray evolution were also derived from schlieren im-ages.The results show that the ignition delay and flame lift-off length of blend fuel are shorter than those of diesel be-cause of its high cetane number.It is also found that the penetration velocity of reacting spray is higher than that of inert sprays because of density drop caused by combustion.In addition,it can be observed that the penetration velocity of blend fuel during quasi-steady spray phase is higher than that of diesel because of higher low calorific value.