11th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
The flow field of a typical steam valve geometry used for large power stations is computed with CFD methods at different operation conditions. Unsteady CFD calculations using the Zonal-Forced-LES model are performed to model the flow instabilities and the dynamic forces. These time-dependent forces are transferred to highly non-linear time-dependent FEM calculations to analyse the vibration level generated by the dynamic forces. The flow analysis shows that wall jet separation, shear layer instabilities and acoustic modes contribute significantly to the dynamic steam forces at part load operation. Geometry modifications which affect these phenomena are presented and evaluated at different operation conditions.