中文摘要：

柴油机的喷油过程对缸内的燃油雾化、油气混合及燃烧有重要影响。运用双流体模型及空穴模型对某两气门柴油机用非均匀布置的5孔无压力室喷油器进行数值模拟，计算分析了循环喷油量对各孔喷油特性的影响；实测了该5孔无压力室喷油器各孔的喷油规律和循环喷油量。各孔喷油规律的模拟值与实测值吻合较好。研究结果表明：循环喷油量增加，各孔喷油速率及流量系数也增加，但各孔平均流量系数的不均匀系数不受影响，说明各孔间流量系数的差异是喷孔布置结构的不同导致的。

英文摘要：

The injection process of diesel engine is important to the fuel atomization, air fuel mixture and combustion. A three-dimension model of a valve covered orifice （VCO） injector with five holes used in a two-valve diesel is established. The simulation of internal flow characteristics inside each nozzle hole of the VCO injector is based on two-fluid model and cavitation model. The fuel injection rates of each nozzle hole and the cycle fuel injection quantity of this injector were measured. The simulated and measured fuel injection rates of each nozzle hole are compared and analyzed. Their differences are under limits. The simulated results show that the injection rate and discharge coefficient of each hole are increased with the cycle fuel injection quantity. The cycle fuel injection quantity has little effect on the mean discharge coefficient unevenness of each nozzle hole. There is discharge coeffwient unevenness of each nozzle hole, and this is mainly due to the structure difference among the holes.