A Study of the coarse droplet formation from the liquid film in steam turbines

Abstract

For all the deployment of the non-fossil energy sources the steam turbine remains the most important energy transforming device. In the current situation when the daily operation of the turbines is not predictable due to electricity supply from the photovoltaic and the wind power plants, the turbines work in the non-design conditions, the danger of the blade’s erosion caused by the coarse droplets is assumed. The purpose of this paper is to suggest the possible formation process of the coarse droplets in the steam turbine. The current studies were focused mostly on the measurement or identification of the coarse droplets in the steam turbine, but the explanation of the archived results was not sufficient. An analysis of the droplets formed in the wind tunnel indicates, for the majority of the measurements, the part of the formed droplets is bigger than the critical Weber number limit. Similar, but less detail, experience was achieved for measurement in the steam turbine. This paper introduces simple analysis of the optically measured coarse droplets size distribution with the modelled flow field behind the blade fitted by measured velocity field. A detailed hot wire measurement was performed in the vicinity of the trailing edge where the liquid film is disrupted to the coarse droplets.