Secondary Flow Structures and Resultant Exit Flow Angle Fluctuations in High Pressure Steam Turbine Stage

The object of investigation is the stage, the geometry and flow conditions of which are typical for a series of steam turbines in operation in Polish power plants. The flow analysis is based on the CFD calculations performed using FlowER, a specialized URANS code developed for studying unsteady phenomena in turbine stages and sections. The paper presents flow patterns illustrating the interaction between vortices inside and downstream of the rotor passage and the resultant exit flow angle (EFA) fluctuations recorded at the stage exit. An attempt is made to attribute individual EFA fluctuations to particular vortices and their development stages.