Distribution of condensation droplets in the last stage of steam turbine under small flow rate condition

The parameter variation, condensation and distribution of wet steam are very complicated when the steam turbine works under small flow rate condition. In this paper, the two-phase fluid model, the homogeneous nucleation model and the droplet growth model are combined to study the parameter variation in the last stage flow field, the condensation and distribution rule of wet steam and the interaction among them under small flow rate condition. The results show that the condensation location of wet steam, the number and size of droplets are influenced greatly by the location of vortex and the parameters of flow field. The droplet is mainly distributed on the side of pressure surface and the downstream of trailing edge of rotor blade. And the distribution of droplet corresponds to the distribution of the vortex. At 5%THA condition, the flow angle fluctuates violently, and the velocity triangle presents a distribution of "X" shape. Besides, the vortex at corresponding locations is obvious, which corresponds to the distribution of droplets. The larger the droplet number, the larger the droplet size is.