To stimulate a fluid stream to disperse into mono-disperse droplets, a new method and a rationed rotating membrane system using periodical switch-on between the rotating membrane and micro-nozzle were introduced. The effects of jetting velocity and rotation speed on droplet generation were investigated. It was found that the droplet size decreased with the increase of rotation speed and with the decrease of jetting velocity. However, the jetting velocity had little influence on the droplet size when the rotation speed was high enough (n=350 rpm in this case). To elucidate the influence of the processing conditions, a theoretical model has been developed, in which the cutting process (based on the linear stability theory) and the crawling process (based on the torque balance) have both been defined and considered. Using this coupling model, the droplet diameters were predicted, showing good agreement with the experimental results. (c) 2010 Elsevier Ltd. All rights reserved.