During the aeromechanical design process of turbomachinery blading, one of the main goals is to improve the blade loading which may lead to a higher risk of flutter. To avoid flutter induced blade failure during operation, the final blade design has to fulfill certain aero mechanical requirements. These refer to the permitted static and dynamic stress levels as well as the aeroelastic stability constraint of flutter for the whole operating range. In this contribution, an efficient workflow for three-dimensional viscous flutter stability analyses will be presented using the three-dimensional viscous flow solver TBLOCK and the open-source software package CalculiX for FE modal analyses. For this purpose, the workflow is applied to the first compressor rotor of a state of the art gas turbine. The flutter analysis is performed for several operating points to predict an accurate flutter envelope for the whole operating range of the investigated compressor stage. To reduce the numerical effort, only the first two mode shapes are considered with respect to different shaft speeds. In addition, phase-shifted boundary conditions are applied to all flutter calculations using the traveling wave mode domain taking all possible inter-blade phase angles into account. The results of the flutter analysis show no indications for flutter within the projected operating range of the rotor and for the considered mode shapes. In conclusion, the described workflow is able to determine the critical flutter stability boundaries of the investigated compressor rotor with reasonable numerical effort.

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