Analysis of internal flow characteristics for GDI injector

Research and/or Engineering Questions/Objective The performance of injector is very important to gasoline direct injection (GDI) engine control. The influence factors of internal flow characteristics for injector were researched. Methodology The Euler multi-fluid model was built and used to analysis. Based on analysis of the internal flow with different mediums and different pressure difference, the flow characteristics of nozzle outlet orifice section were studied. Results The discharge coefficient of nozzle was mainly influenced by the degree of cavitation. With the increase of cavitation level, the average velocity added and turbulence energy decreased on nozzle outlet orifice section. The cavitation level was depended on the bubble number density and pressure difference of inlet and outlet of injector. Limitations of this study Spray characteristics of GDI injector should be investigated based on the results of this paper. What does the paper offer that is new in the field in comparison to other works of the author Most previous analysis of occurrence position for cavitation phenomenon and influence parameters are from macroscopic perspective. This paper mainly analyzes microcosmic influence factors of the cavitation phenomenon within a GDI injector, and then the flow characteristics on orifices export section, which could provide experiential data for later spray simulation, and meanwhile important basis for simulation of the internal flow process. Conclusion The cavitation level was mainly influenced by initial value of bubble number density, and increased with it added. Under the same condition, saturated vapour pressure of medium was higher, the influence of bubble number density was much greater. After the bubble number density was greater than 1e + 12, the cavitation flow inside the injector tends to be stable. When pressure difference of inlet and outlet of injector was increased, cavitation intensified.