The concept of coaxial porous injector design for gas-liquid mixing involves improved momentum transfer between the gas and liquid jets by changing the gas injecting direction of a conventional liquid-centered shear coaxial injector from parallel to perpendicular using porous material. Cold-flow tests of the coaxial porous injector and the shear coaxial injector in two-dimensional configurations were carried out to compare the macroscopic characteristics of sprays from each injector and to understand the effects of spraying conditions on the breakup length and the spray angle. The spray patterns were visualized using the shadowgraphy technique. The shadowgraph images recorded in high speed were post-processed to detect the breakup length and the spray angle. The post-processing code filters the dynamic pixels, and leaves the stationary pixels, which corresponds to the liquid core and the background. The most significant differences between the porous injector and the shear injector in the two-dimensional configurations were the spray angle and the uniformity of the disintegrated liquid jet. The liquid column from the shear injector was not split off entirely, and only the portion at the interface between the gas and liquid jet was atomized by the shear force. On the other hand, the liquid jet from the porous injector dispersed more widely, and was disintegrated into droplets more completely in most experimental cases of similar axial momentum flux ratio conditions at the injector tip, and it was thought that an optimal porous element length for the best mixing performance exists at certain injection conditions.