This study visualizes the internal characteristics with analysis by velocity while changing the internal plunger gaps of a natural gas injector. The design of the injector is illustrated with specifications for the real gap sizes of plungers and needles which amputate the internal flow layers. Also, for accuracy of the analysis, the mass flow’s data from the plungers is obtained at the front and back face using the mesh sizing function. Results of analysis show linearly increasing velocity between the inlet and boundary area from gap 0.025mm to 0.015mm, and also an unconverted trend by choking state as a similar figure of velocity change from gap 0.175mm to 0.200mm. According to the analysis results, mass flow is supplying the internal injector and somewhat lacking in comparison with the target flow result in the case of setting 0.0013kg/s and demonstrated a transmissive point of the more excessive mass flow in the case of 0.0055kg/s. The optimum mass flow result for velocity which reaches the internal injector has a flow value of 0.0034kg/s and is also most suitable for supplying flow efficiency.

natural gas injector, flow layer, injection hole, needle, plunger.