定容弹内煤制油喷雾及着火特性的可视化研究

Visualization of Coal-to-Liquid Spray and Ignition Characteristics in Constant Volume Bomb

煤制油的生产工艺成熟、来源广泛,有利于降低我国对石油进口的依赖。通过定容燃烧弹进行了可视化研究,分析了煤制油在不同环境条件下的喷雾和着火特性。研究结果表明,煤制油喷雾和柴油喷雾在不同工况下均表现出良好的一致性,喷雾发展趋势相同。当环境温度保持500 K不变,随着环境压力由3 MPa提高到6 MPa,煤制油喷雾的贯穿距减小了22.67%,而喷雾锥角增大了46.9%。随着环境温度的提高,大量燃油液滴在破碎后迅速汽化,故喷雾贯穿距和喷雾锥角均表现出明显的降低趋势。在高环境压力下,煤制油的着火时刻提前,火焰浮起长度由38.8 mm缩短至30 mm,并表现出良好的球形火焰形态。与柴油相比,煤制油喷雾的贯穿距较短而锥角较大。在500 K,6 MPa的环境条件下,煤制油和柴油的喷雾贯穿距分别为46.4 mm和49.6 mm,表明煤制油在实际使用时更不容易产生撞壁现象。

Coal-to-liquid production process is mature and widely available,which is conducive to reducing China's dependence on oil imports.A visualization study was carried out by means of a constant volume combustion bomb to analyze the spray and ignition characteristics of coal-to-liquid under different environmental conditions.The results show that the coal-to-liquid and diesel sprays have good consistency under different working conditions and the spray development trend is the same.When the ambient temperature keeps constant at 500 K,the penetration distance of coal-to-liquid spray decreases by 22.67%and the spray cone angle increases by 46.9%as the ambient pressure increases from 3 MPa to 6 MPa.With the increase of ambient temperature,a large number of fuel droplets rapidly vaporize after crushing,so the spray penetration distance and spray cone angle show a significant downward trend.Under the high ambient pressure,the ignition timing of coal-to-liquid advances,the flame floating length shortens from 38.8 mm to 30 mm,and shows a good spherical flame pattern.Compared with diesel,the penetration distance of coal-to-liquid spray is shorter and the cone angle is larger.Under the ambient conditions of 500 K and 6 MPa,the penetration distances of coal-to-liquid and diesel spray are 46.4 mm and 49.6 mm respectively,which indicates that the coal-to-liquid is less prone to the phenomenon of wall impingement in practical use.