Abstarct: Liquid fuel injection into air-jet flow provides high fluid penetration, rapid air mixture, and performance enhancement. It has numerous applications in airbreathing propulsion systems (including gas turbine, internal combustion engine, and ramjet), liquid rocket engine, and fuel injection. In this research performed in the laboratory, the water-jet breakup patterns are studied by the impinging of water and air jets in different flows. In the subsequent research, the average sizes of the droplets in axial and radial distances are acquired using image processing in LabView software. Particular image processing is implemented to calculate the speed of a droplet, which could be applied to calculate the velocity of the droplet in different axial distances under the impinging point. The effects of some parameters such as impinging angle and water and air flows are evaluated in water-jet formation. The primary parameters effective on the injection structure are recognized. A parametric study is performed on air-water momentum ratio, air-water momentum flux ratio, and air-water flow ratio. This investigation is conducted after recognition of the mentioned parameters that are highly influential on injection properties. In general, the experimental results revealed that the momentum flux of the air-jet compared with the water-jet has a more prominent role in the water-jet breakup. Increasing air-jet momentum flux in water or increasing airflow rate culminate in an improved breakup. In this research, the water-jet plate with membrane breakup and fiber breakup models underwent breakup in low and high velocities, respectively. In addition, it is observed that by increasing the speed of air at the impinging point, the instabilities on the water jet are intensified. Parameters such as air-water momentum ratio, air-water momentum flux ratio, air-water flow ratio, and impinging angle are studied to describe the average value of sauter mean diameter of injection. The efficiency of impinging jet injectors is analyzed for water in several air-water flow ratios with the help of air. Two different injection angles are defined in this study to describe the injection structure, including the deviation (β) and divergence (α) angles. Furthermore, the volumetric water flux density is investigated in different time pulses.