Spray characteristics of a liquid–liquid coaxial swirl atomizer at different mass flow rates

An experimental investigation is performed to explore the characteristics of sprays produced by a liquid–liquid coaxial swirl injector in a non-combusting environment. Phase Doppler anemometry is used for the measurement of velocity and Sauter Mean Diameter of droplets across and along the injection axis for various inner- and outer mass flow rates. Results of the combined spray are compared with those of inner- and/or outer spray alone. The results indicate that the inner injector has a larger influence on the flow field of the combined spray compared to the outer one. Further, the maximum velocity of the combined spray is close to the center of the spray thickness and the velocity decreases downstream of the nozzle. However, the maximum Sauter Mean Diameter of droplets along the injection axis moves to the outer periphery of the spray and increases downstream. Furthermore, the combined spray flow field is self-similar in terms of velocity and the average Sauter Mean Diameter of the droplets.