AXIAL TURBINE BLADE VIBRATIONS INDUCED BY THE STATOR FLOW Comparison of Calculations and Experiment

The forced excitation of the rotor blades of a single-stage turbine due to rotor- stator interaction is calculated with an in-house unsteady flow solver and a gen- eral purpose finite element code. A scaled configuration is used in order to re- duce the amount of computational effort. The unsteady flow solution is obtained on three blade-to-blade cuts. The time dependent static pressure on the blade surface is Fourier transformed with respect to the vane passing frequency and the relevant Fourier modi of the original three blade profile cuts are interpolated to the overall blade height. This Fourier transformed flow solution is transferred to the finite element model where the blade excitation is obtained. Two reduced geometrical rotor-stator configurations are investigated and compared with re- spect to the flow field and the resulting blade excitation.