This paper presents the result of experimental and theoretical studies of an siphon fed externally mixed air blast atomizer. In this type of the atomizer, atomization is attained by injecting a air stream at tip of the water injection port. The water is siphon fed because of the pressure difference. The result presented in this paper indicate that flow becomes supersonic beyond the supply pressure of 0.8 bar. This paper also describes the prediction of mathematical model that depics the two phase flow in externally mixed atomizer. The model uses compressible flow relationships to predict the air flow rate, a neural network based model to predict the water flow rate and a novel droplet formation model to predict the droplet SMD. A statistically distributed Weber number criterion is used to estimate the sizes of the droplets produced in the atomization process. The liquid flow rate, air flow rate and sauter mean diameter predicted by model are compared with the experimental data and they are found to be in fair agreement with each other, suggesting that model properly describes the physics of two- phase flow within the atomizer.
