出口压力对柴油喷油器流量特性影响的试验研究

柴油机高压燃油系统中,喷油器内部燃油的高速流动易导致喷孔内部出现空化,从而影响喷油特性。为了研究喷油器的进出口压力对燃油在喷嘴里的流动的影响,设计了一套出口压力可调的试验装置,针对高压共轨喷油器进行了不同出口压力下的喷油规律测量,研究了出口压力对喷油率的影响。试验发现:由于进出口压力差很大,喷嘴内部为空化流动;空化流动时,当入口压力不变时,改变出口背压,喷油率不变化,流动出现阻塞现象;出现空化后,增加出口压力,流量系数增大。

Experimental Study of Influence of Outlet Pressure on Discharge Characteristics of Diesel Injector

The high-speed flow of fuel in the injector of the high pressure fuel system for the diesel engine is easy to induce the cavitation in nozzles, which affects the injection characteristics. A set of test rigs is built to adjust the different outlet pressures for the study of the influence of outlet pressure on the discharge characteristics of injector. The injection characteristics of a high-pressure common-rail under different injection and outlet pressures are measured to investigate the influence of outlet pressure on fuel delivery rate. The test results show that the outlet pressure has little influence on the fuel delivery rate at the constant injection pressure; but as the flow chokes due to cavitation, the discharge coefficient increases with the increase in the outlet pressure.