14th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
A significant share of the conversion of thermal into electrical energy is realised by steam turbines. Formerly designed for continuous operation, today's requirements include extended part load operation that can be accompanied by highly unstable flow conditions and vibrations within the control valve of the turbine.The prediction of the flow at part load conditions requires large computational efforts with advanced turbulence modelling in order to compute the flow at a reasonable accuracy. Due to the unsteadiness of the flow, the evaluation of the numerical results itself is a major challenge. The turbulent structures require statistical approaches of which the use of Spectral Proper Orthogonal Decomposition (SPOD) has proven itself as a powerful method. Within this paper, the application of the method on a critical operating point with a temporal excitation of pressure oscillations is presented. Using SPOD, the dominating flow phenomena have been isolated and flow structures are visualized.