Computation of Unsteady Blade Forces in Turbomachines by Means of Potential Flow Theory and by Simulating Viscous Wakes

Abstract

This paper describes a new theoretical model which computes two main excitation mechanisms, one based on the potential flow theory and the other explainable by the motion of blades through the wakes of preceding blades. The computation of the potential flow field is based on the assumption of a plane, unsteady, incompressible flow. Fluctuations of circulation caused by an alternating velocity field are taken into account by free vortex paths. Blade surfaces are modeled by a vortex distribution. Viscous wakes are simulated by means of contrarotating vortex rows. Results of the theoretical approach are compared with experimental data measured in axial turbomachines.