عنوان مقاله [English]
The purpose of the present work is to investigate effects of the pressure ratio and the ratio of the injected gas density to the combustion chamber on its axial and radial penetration lengths and the tip velocity on a multi-hole gaseous injector. In direct injection gaseous fueled engines, very short times are available for the mixture preparation. Therefore, the exact determination of gaseous jet characteristics emanating from the injector is very important. For this objective, ultra high speed Schlieren imaging of the transient jet with high spatial and temporal resolutions were utilized. Jet images were analyzed by a digital image processing method based on the edge detection approach, using an in-house software. Results revealed that regarding to velocity curves, the formation of the multi-hole gaseous jet was comprised of three stages (including the emergence of individual plumes, merging and the penetration of the main spray). It was also found that changing the chamber gas density would not alter maximum and minimum times in velocity curves. Decreasing the density ratio of the injected gas into the chamber would decrease the axial penetration and the jet tip velocity and would increase the jet spreading angle.