| The inlet parameter of steam turbines, such as nuclear steam turbines, are low and the middle-reheatting cycle is unable to work on these steam turbines. And so the problem of humidity on them becomes much worse. The scientific research workers nowadays are engaged in studying a effective technology of removing humidity abroad and at home, by which they try to decrease the steam humidity in turbine passages. Moisture removal stage technology is one of important high efficiency method to ensure permissible values of the steam wetness. The purpose on this paper is to study the pneumatic characteristic of moisture removal stage and the movement performance of water droplets in it on the method of computational fluid dynamics (CFD), by which it will be hoped to assist work during engineering.The Mixing Plane Model will be used in studying the pneumatic characteristic. Some geometry characteristics in this stage are as fellows: seven grooves on the suction face, a cap on the top of the rotor blade, one orifice in the middle of the cap, a clearance of some certain thicknesses between the cap and a hull of the stage, one bore in the hull. Three structures will be emphasized on this paper in order to achieve the influence of these geometry characteristics to the bucket in its flow characteristic. They are a stage with one clearance, seven grooves and one cap, a stage with one clearance and one cap and one with none of them. It also discusses on this paper the performance of second water droplets on the rotor blade by adopting Discrete Phase Model.Some conclusions attained by the numerical simulation are as fellows: The cap and the orifice in it are the most reasons to bring flow breakaway and loss on the surface of the blade, which decrease the airflow work ability to the rotor blade; Grooves influence the distribution of flow lines on the surface of suction and they also produce flow breakaway and loss in themselves, but they are not able to bring...
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