Flutter analysis of a steam turbine blade with frequency and time-domain solvers

Authors

Christian Frey - German Aerospace Center (DLR)
Graham Ashcroft - German Aerospace Center (DLR)
Hans-Peter Kersken - German Aerospace Center (DLR)
Daniel Schlüß - German Aerospace Center (DLR)

Abstract

The aim of this paper is to assess the capabilities of different simulation approaches to predict the flutter stability of a steam turbine rotor. The focus here is on linear and nonlinear frequency domain solvers in combination with the energy method which is widely used for the prediction of flutter onset. Whereas a GMRES solver is used for the linear problem, the nonlinear methods employ a time-marching procedure. The solvers are applied to the flutter analysis of the first rotor bending mode of the open Durham Steam Turbine test case. This test case is representative for the last stage of modern industrial steam turbines. We compare our results to those published by other researchers in terms of aerodynamic damping and local work per cycle coefficients. Time-domain, harmonic balance, and time-linearised methods are compared to each other in terms of CPU efficiency and accuracy.