Three-dimensional calculation of low-frequency unsteady transonic flow in axial turbine stages (Dreidimensionale Berechnung der niederfrequent instationaeren, transsonischen Stroemung in Axialturbinenstufen)

A finite volume method has been developed for the study of the unsteady processes resulting from the inhomogeneous flow fields in the runners of axial turbine stages. The method permits the three-dimensional frictionless calculation of low-frequency unsteady flows. The varying flow quantities around the perimeter are modeled as corotating rotor blade systems under time-dependent boundary conditions. The resulting cascade pressure distributions are used to determine the cyclic stress amplitudes resulting from the dynamic loads. (C.D.)