We analyze the velocity characteristics regarding plunger area inside NG injector, which is changed by stroke from electronic pulse signal, at variable condition from 0.1mm to 0.2mm with CH₄ gas. An actual mode was designed by sleeve, spring and forth hole and, the plunger was manufactured by material of stainless steel 401, which was designed to divide into top and bottom areas, from plunger assay. The models for analysis were divided into 5 types, which were designed by assumed structures which were modified by 0, 2, 4, 6 and 8 of plunger wing shapes. The velocity characteristics of stroke 0.1mm were verified to quickly increase the contoured distributions at model (b) which has 2 plunger wings inside injector. And the fast velocity at internal plunger exposed to change performance in order of model (b) > (c) > (d) > (e) > (a) at plunger areas. Consequently, the cause for such observation is attributed to further activation of velocity, since flow of velocities inside the injector was stabilized as opening of stroke positioned, at the bottom part of plunger which was changed from 0.1mm to 0.2mm.

natural gas, injection, plunger, diffusion, velocity.