A model for predicting the spray behavior in an air swirl was developed. High speed Schlieren photographs of a non-evaporating spray in an air swirl were taken with a constant volume vessel which can generate various swirl intensities. A close observation of the photographs revealed that the spread of the spray in the direction perpendicular to the swirl flow is hardly affected by the swirl flow and that the spray is roughly divided into two regions; the main jet region which possesses a major part of momentum and the peripheral region which is torn off the main jet region by the swirl and flows with the same velocity as the local swirl velocity. Basing on this observation a 2-D model proposed by Sinnamon et al. was modified, so that the model was able to predict the spread, trajectory and penetration of a spray in a satisfactory manner.