Characteristics of moisture losses in low pressure steam turbine stages

This paper describes characteristics of moisture losses in low pressure steam turbine stages. Steam turbines operating under wet-steam conditions experience thermodynamic and mechanical losses caused by the presence of moisture. In order to predict the moisture losses, physics-based moisture loss models are developed. The moisture loss models are composed of six categories: supersaturation loss, condensation loss, acceleration loss, braking loss, capturing loss and pumping loss. These losses are calculated according to the wetness levels in the stationary blade & moving blade rows, and defined by the functions of steam properties and design factors of turbine stages. The loss models are compared to full-size low pressure steam turbine data for prediction of the overall moisture losses. The developed loss models are found to be effective for designing wet-steam turbines from the standpoint of calculation accuracy and calculation time. © 2013 The Japan Society of Mechanical Engineers.