Influence of regeneration-induced variances of stator vanes on the vibration behaviour of rotor blades in axial turbines

Authors

J. Aschenbruck, C.E. Meinzer, J.R. Seume - Leibniz University of Hannover,Germany

Abstract

The regeneration of highly loaded turbine blades causes variances in geometrical parameters. To determine such typical, regeneration-induced variances of turbine blades, refurbished blades of aircraft jet-engines are analysed and significant variations of different geometrical parameters are identified. These characteristic variances are applied to stator vanes of the investigated turbine stage. In the next step, steady-flow CFD simulations are performed with these varied vanes to evaluate the effects of geometric variances on their aerodynamic performance. This analysis indicates a high influence on the total pressure-loss coefficient of the varied vanes. The variation of the trailing-edge thickness, the blade thickness, and the variation of the chord length have effects of comparable magnitudes. Based on these results, the influence of the trailing-edge variation on the low engine-order excitation is investigated using a forced response analysis. It is shown, that the vibration amplitudes of some modes are significantly higher due to the geometrical variation.