A 3D method to evaluate moisture losses in a low pressure steam turbine: Application to a last stage

This paper presents a physically consistent 3D method to evaluate moisture losses and it is further employed to estimate the moisture losses in the last stage of a 1000 MW fossil-fired steam turbine. The 3D method is based on the information of the flow-field and droplets deposition. An inhomogeneous multi-phase flow model is adopted to simulate the condensing flow in the last stage. Massive computations of droplets deposition by both inertial and turbulent mechanisms on the stationary blade and moving blade have been conducted for different droplet diameters at the inlet of the last stage. In our work, the moisture losses are divided into six categories namely thermodynamic loss, drag loss of fog droplets, drag loss of coarse droplets, impact loss, capturing loss and centrifuging loss. The effect of the fog droplet size at the inlet of the last stage on the moisture losses has been analyzed and the results indicate that the overall moisture losses rise and the relative fractions of each category of the moisture losses vary against the increase of the fog droplet diameter. (C) 2015 Elsevier Ltd. All rights reserved.