Bistable Flow Occurrence in the 2D Model of a Steam Turbine Valve.

The internal flow inside a steam turbine valve was investigated experimentally using PIV measurement. The valve model was proposed to be two-dimensional. The model was connected to the blow-down wind tunnel. The flow conditions were set by the different position of the valve plug. Several angles of the diffuser by diverse radii were investigated concerning flow separation and flow dynamics. It was found that the flow takes one of two possible bistable modes. The first regime is characterized by a massive flow separationjust at the beginning of the diffuser section on the one side. The second regime is axisymmetric and the flow separation is not detected at all. [ABSTRACT FROM AUTHOR]