Measurements and analyses on the two-phase fuel transient flow characteristics of dual fuel co-direct injector

Abstract

In this research, an innovative two-phase fuel transient flow coefficient measurement system is proposed to investigate the flow characteristics and coupling effects of two-phase fuel, and to fill the gap of the two-phase fuel flow characteristics measurement technology of dual fuel injector. For this purpose, microphotography technology is used to obtain the original image of the injector hole, and the accurate area of the injector hole can be obtained by image processing. The two-phase injection momentum and the transient injection pressure are measured by the impact force sensor and the pressure sensor respectively, and the two-phase fuel transient flow coefficient is obtained. Due to the change of the increasing rate of the effective flow area at the nozzle, the gas transient flow coefficient shows two different increasing trends during the upward stage of the gas needle valve. With the background pressure increase, the maximum gas transient flow coefficient decreases and injection duration increases. The influence of pilot diesel injection on subsequent gas injection stages is mainly reflected in that when the gas energizing time is 0.8 ms, the fluctuation range of gas mass flow caused by diesel injection is 52.6%, and the fluctuation range is 14.9% when the gas energizing time is 2 ms, but the influence of diesel injection on the peak value of gas transient flow coefficient can be ignored.