The effects of nozzle geometry on diesel spray characteristics were studied in a spray chamber under evaporating conditions using three single-hole nozzles, one cylindrical and two convergent, designated N1 (outlet diameter 140 μm, k-factor 0), N2 (outlet diameter 140 μm, k-factor 2) and N3 (outlet diameter 136 μm, k-factor 2). Spray experiments were performed with each nozzle at two constant gas densities (15 and 30 kg/m3) and an ambient temperature (673 K) at which evaporation occurs, with injection pressures ranging from 800 to 1600 bar. A light absorption and scattering method using visible and UV light was implemented, and shadow images of liquid and vapor phase fuel were recorded with high-speed video cameras. The cylindrical nozzle N1 yielded larger local vapor cone angles than the convergent nozzles N2 and N3 at both gas densities, and the difference became larger as the injection pressure increased. The vapor phase penetration values for nozzle N1 and N3 were quite similar and always lower than those for N2. This is consistent with the impingement measurements, which showed that the momentum flux of nozzle N1 was only slightly greater than that of nozzle N3, while that of nozzle N2 was substantially greater. The vapor volume fractions measured along the spray’s center line were well explained by the one-dimensional transient diesel jet model, indicating that diesel spray vaporization is controlled by turbulent fuel-air mixing.
展开▼
机译：在使用三个单孔喷嘴，一个圆柱形和两个会聚，指定的N1（出口直径140μm，k因子0），N2（出口直径140），N2（出口直径140），在蒸发条件下在喷射条件下进行喷嘴几何形状对柴油喷射特性的影响μm，k系数2）和n3（出口直径为136μm，k因子2）。用每个喷嘴在两个恒定气密（15和30kg / m 3）下进行喷雾实验，并且发生蒸发的环境温度（673k），注射压力范围为800-1600巴。利用高速摄像机记录了使用可见光和UV光的光吸收和散射方法，并用高速摄像机记录液体和气相燃料的阴影图像。圆柱形喷嘴N1在两个气体密度处产生比会聚喷嘴N2和N3更大的局部蒸汽锥角，并且随着喷射压力的增加而变大。喷嘴N1和N3的气相渗透值非常相似，总是低于N 2的那些。这与冲击测量一致，这表明喷嘴N1的动量磁通量仅略大于喷嘴N3的动量，而喷嘴N2的动量均基本上更大。沿喷雾中心线测量的蒸汽体积分数通过一维瞬态柴油喷射模型很好地解释，表明柴油喷射蒸发由湍流燃料 - 空气混合控制。
展开▼
