柴油喷雾粒径空间分布特征理论与实验研究

为研究小型柴油燃烧器压力雾化喷嘴在喷雾外流场空间内的柴油喷雾粒径分布特征,采用激光粒度仪测量沿喷嘴出口轴向方向各截面处的液滴粒径分布。分别测试了不同配风量,不同喷油压力,不同喷雾锥角和油量条件下在 5 ~ 50 cm截面处的粒径分布,对其液滴平均索特尔直径进行分析,用分散指数表征液滴分布的均匀性。研究表明,喷雾粒径在空间的整体分布是在喷雾出口处区域最小,在浓雾区粒径最大但分布均匀。随风量和油压的减小,平均粒径增大,喷雾锥角对粒径影响不大,而油量对全局的空间分布影响较大。液滴在风量大的浓雾区分布均匀,但油压超过 1.2 MPa,初始破碎区的均匀度反而下降。初始破碎区的液滴粒径受液滴间相互作用影响,结合实验结果,引入液滴群整体作用系数B对理论推导的临界破碎粒径公式进行修正,平均误差5%。

Theoretical and Experimental Study on Spatial Distribution Characteristics of Diesel Spray Particle Size

In order to investigate the particle size distribution characteristics of pressure atomizing nozzles of Low power diesel burners in the space of spray outflow field, the laser particle size meter was used to measure the droplet size distribution in each section of axial direction along burner nozzle outlet. The particle size distribution at the section of 5 ~ 50 cm with different air volumes, injection oil pressures, spray cone angles and fuel quantities were tested respectively. The Sauter Mean Diameter of the droplets were analyzed, and the uniformity of droplet distribution was characterized by the dispersion index. The results show that the overall distribution of spray particle size in space is the minimum in the spray exit region and the maximum but uniform in the dense foggy region. With the decrease of air volume and oil pressure, the average particle size increases, and the particle size is less affected by spray cone Angle, while the fuel capacity has a greater impact on the global spatial distribution. The droplet was evenly distributed in the dense fog region with higher air volumes, but the uniformity of the initial crushing area decreased when oil pressure exceeds 1.2 MPa. The droplet size in the initial crushing zone is affected by the interaction between droplets. Combined with the experimental results, the action coefficient B of the droplet group is introduced to correct the theoretical formula of critical crushing particle size. The error is within 5%.