Visualization Experiment and Numerical Analysis of Cavitation Flow Characteristics in Diesel Fuel Injector Control Valve with Different Structure Design

Increasing the injection pressure has been proven an effective method to enhance performance and reduce pollutant of diesel engine. With the increase of the injection pressure, the cavitation damage problem inside common rail fuel injector is more significant, which has direct influences on reliability of diesel engine. While the most studies so far have focused on cavitation occurred in injector nozzle and its atomization characteristics, few researchers studied the cavitation phenomenon in fuel injector control valve. But due to the complexity of flow field and difficulty of experiment, the cavitation in control valve could not be fully described by existing theories. In this paper, the two-dimensional visualization experiment and numerical simulation of control valve was implemented to acquire the image of cavitation intuitively and validate the simulation method and model. Then a new structure design of control valve named convergent model was presented for comparison. The origin model and convergent model with different valve lifts were simulated in three dimensions. The results showed that the sheet cavitation occurred at the surface of seal cone and steel ball then turned to cloud cavitation in downstream area. The intensity of cavitation increased with the increase of valve lift. Convergent model could efficiently reduce the cavitation intensity near the seal area. This research could provide references for engineering optimization design of control valve.