为探明超高压条件下多次喷射燃油喷雾发展特性，利用高速摄影直拍技术，对高背景密度条件下超高压多次喷射喷雾发展特性进行了研究。研究结果表明：在背景温度303 K，喷孔直径0.148 mm，背景密度60~140 kg/m³，喷射压力200~250 MPa条件下，随背景密度增加，燃油喷雾纵向发展受阻，燃油堆积后向径向发展，导致喷雾贯穿距减小（最大减小26%），喷雾锥角增加（最大增加17%）；提高喷射压力可以同时提高燃油喷雾纵向及径向的扩散能力；在预喷比例10%~30%，预主喷间隔0.4~1.6 ms范围内，由于主喷燃油与预喷燃油之间的追击效应，使得多次喷射主喷喷雾贯穿距离大于单次喷射，随着预喷油量的增加、预主喷间隔时间的缩短，追击效应加强，主喷喷雾贯穿距增加（最大增加18%）；由于主喷燃油对预喷燃油的推动作用，预喷燃油喷雾相对单次喷射燃油喷雾贯穿距离增加，且间隔时间越大，主喷燃油对预喷燃油的推动作用越弱，当间隔时间为1.2 ms时，单次喷射和预喷射喷雾贯穿距离基本相同，推动作用已不明显。

 

In order to investigate the development characteristics of multiple injection fuel spray under ultra-high pressure condition, the development characteristics of multiple injection spray for ultra-high pressure fuel supply system were studied by using high-speed photography under high background density. The results show that the longitudinal development of fuel spray is hindered, and fuel accumulation promotes radial development, resulting in the decrease in spray penetration distance(up to 26%) and the increase of spray cone angle(up to 17%) with the increase of background density under the conditions of background temperature 303 K, nozzle diameter 0.148 mm, background density 60-140 kg/m³, and injection pressure 200-250 MPa. Increasing the injection pressure can improve the longitudinal and radial diffusion ability of fuel spray. Due to the pursuit effect between the main and pilot injection fuel, the penetration distance of multiple injection main spray is larger than that of single injection in the range of 10%-30% pilot injection ratio and pilotmain injection interval of 0.4-1.6 ms. With the increase of pilot injection fuel mass and the shortening of pilot-main injection interval time, the pursuit effect strengthens, and the penetration distance of main injection increases(up to 18%). Due to the driving effect of main injection fuel on the pilot injection fuel, the penetration distance of pilot injection fuel spray increases compared with the single injection fuel spray, and the longer the interval time between pilot-main injection, the weaker the driving effect of main injection fuel on the pilot injection fuel. When the interval time is 1.2 ms, the penetration distances of single and pilot injection spray are approximately equal, and the driving effect becomes negligible.