عنوان مقاله [English]
In this paper high speed Schlieren method was employed for measurement of the geometrical characteristics of transient gaseous jet. Axial jet penetration and its angle versus time were calculated in pressure ratios of 2, 3 and 4 and three different nozzle diameter of 0.4, 0.5 and 0.6. using digital image processing method by analyzing of the Schlieren images of transient helium direct injection jet. For finding edges of Schlieren images the Gaussian filter was applied to images. The J2715 SAE standard was used as a criterion for angle determination. Equivalent diameter was used for non-dimensional analysis of the penetration. Experimental results prove linear dependency of non-dimensional penetration to non-dimensional time with slope of 2.3-2.9. angle measurement showed that jet angle would decrease after time passing from start of the injection and reaches to a constant value at the end of injection. The turbulent stochastic behavior of the jet arise need for repeating the experiments until achieving to acceptable results.