【摘要】 柴油喷油器内部燃油的高速流动易导致喷孔内部出现空化,影响燃油的流通,因此研究喷孔内燃油空化过程具有重要的意义。在比例放大透明喷孔可视化试验台架上,完成了不同进出口压力下的喷孔流动特性试验,研究了喷孔内的空化规律和对喷孔内流率特性的影响。试验结果表明:当固定入口压力时,随着出口压力的降低,在无空化阶段,流量系数基本不变;当出现空化进入空化发展阶段,空化增强并向出口方向发展,质量流率继续增加,流量系数有所下降;在空化饱和阶段,质量流率不再增加,流量系数加速降低;喷孔的入口压力不影响空化初生和空化饱和对应的临界空化数;喷孔直径不影响空化初生点,但影响空化饱和点,喷孔直径越大,越难达到空化饱和,对应的临界空化数越小;喷孔长度影响空化初生点和空化饱和点,喷孔长度越长,越难发生空化,也越难达到空化饱和,对应的空化初生和空化饱和的临界空化数越小。更多还原

【Abstract】 The high-speed flow of internal fuel in diesel fuel injector is easy to cause cavitation inside the nozzle,which affects the flow of fuel. It is very important to study the cavitation process of fuel in the nozzle. The flow characteristics of the nozzle under different inlet and outlet pressures is studied by experiments on the scale-enlarged visualization test bench. The experimental results show that the inlet pressure is constant,with the decrease in the outlet pressure,1) during the no cavitation period,the discharge coefficient is basically unchanged; 2) during the cavitation developing period,cavitation becomes stronger and develops from the entrance of the nozzle to the outlet,the mass flow rate continues to increase and the discharge coefficient decreases; 3) during the cavitation saturation period,the mass flow rate maintains stable but the discharge coefficient continues decreasing. The inlet pressure of the nozzle does not affect the critical cavitation number of cavitation inception and cavitation saturation. The diameter of the nozzle does not affect the point of cavitation inception,but the point of cavitation saturation; asthe diameter of the nozzle is larger,the more difficult it is to achieve the cavitation saturation,and the smaller of the critical cavitation number. The length of the nozzle affects the point of cavitation inception and cavitation saturation; the length of the nozzle is longer,the more difficult it is to occur cavitation and to achieve cavitation saturation,the critical cavitation numbers of both the cavitation inception and the cavitation saturation are smaller.更多还原