燃油温度和喷射压力对葵花籽油与柴油喷雾特性的影响

Effect of fuel temperature and injection pressure on spray characteristics of sunflower oil and diesel

为探究纯植物油作为压燃内燃机替代燃料的雾化问题,利用纹影法对葵花籽纯植物油和普通柴油在不同试验条件下的喷雾特性进行了对比研究,分析了燃油温度和喷射压力对2种燃料喷雾贯穿距、喷雾锥角和空气卷吸作用的影响。研究结果表明:葵花籽油的喷雾贯穿距和喷雾锥角均随着喷射压力和燃油温度的升高而增大,与柴油的变化规律相似。温度从60℃升高到90℃,喷油压力为60 MPa时喷雾贯穿距和喷雾锥角的平均增幅分别为12.4%和9.6%,120 MPa时分别为5%和4.14%;喷油压力从60 MPa升高到120 MPa,温度为60℃时喷雾贯穿距和喷雾锥角的平均增幅分别为39.7%和16.7%,90℃时分别为30.6%和10.9%;当喷射压力、背景压力和燃油温度相同时,葵花籽油比柴油具有更大的贯穿距和更小的喷雾锥角,且喷雾贯穿距平均增幅为22.5%,喷雾锥角平均降幅为60.3%;升高燃油温度和升高喷射压力都会增强雾注的空气卷吸作用,但葵花籽油的空气卷吸作用要明显弱于普通柴油。研究结果可为纯植物油作为内燃机替代燃料的可行性研究提供参考。

To study the fuel atomization problem when raw vegetable oil is used as an alternative fuel of compression-ignition internal combustion engine, this paper investigated the differences in spray characteristics between raw sunflower oil and regular diesel under different experimental conditions using the Schlieren method. The focus of this study is the effects of fuel temperature and injection pressure on the spray penetration distance, the spray cone angle, and the air entrainment of fuels injected into the constant volume vessel. The results show that both the spray penetration distance and the spray cone angle of the sunflower oil increase with increasing the fuel injection pressure and fuel temperature, which are similar to those of regular diesel. When the fuel temperature is increased from 60℃ to 90℃, the average increases in the spray penetration distance and cone angle of the sunflower oil are 12.4%and 9.6%, respectively, at 60 MPa injection pressure. Such increases are 5%and 4.14%respectively at 120 MPa injection pressure. When the injection pressure is increased from 60 MPa to 120 MPa, the percentage increases in the mean spray penetration distance and cone angle are 39.7%and 16.7%respectively at the fuel temperature of 60℃ and 30.6% and 10.9% respectively at 90℃. When the injection pressure, background pressure, and fuel temperature are the same, the sunflower oil spray has a greater penetration distance but a smaller spray angle than that of diesel. The average increase of the spray penetration of the sunflower oil is 22.5%and the average decrease of spay cone angle is 60.3%. Elevating the fuel temperature or increasing the fuel injecting pressure can enhance the entrainment of air into the spray; However, the air entrainment of the sunflower oil spray is significantly weaker than that in the ordinary diesel spray. The results provide a valuable reference on the spray characteristics to help evaluate the feasibility of using raw vegetable oil as an alternative fuel for internal combustion engines.