In order to determine the improvement of fuel spray property for diesel fuel blended with dimethyl ether(DME),the size distribution characteristics of spray droplet under different mixing ratios,injection pressures and orifice diameters were compared and researched with shadow imaging and digital image processing technology.The results show that the curve of size distribution for blended fuel droplet has a deviation to the direction of small droplet with the increase of DME proportion due to the flash boili...