An Efficient Workflow for Accurate Flutter Stability Analyses and Application to a State of the Art Compressor Rotor

Abstract

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.

A Quick Method for Full Flange-to-flange Industrial Gas Turbine Analysis Based on Through-flow Modelling

“…This solver is executed both for steady-state and unsteady analysis. For the latter case, TBLOCK was recently verified and included in a process chain to handle with blade flutter [17]. The parallelized MPI version was further developed by MAN and is currently used as an efficient working horse for multistage turbomachinery analysis and components of the secondary flow system.…”

Fan casing contouring under consideration of aeroacoustics, mechanics, aeroelasticity, and whole engine performance

“…The casing variation of the rotor tip has significant influence on aeroelastic behavior or the flutter stability. The workflow for accurate flutter stability analysis used for these investigations was published by [9] using the Traveling Wave Mode (TWM) formulation and is applied on the basic and optimized designs of the fan. Moreover, this workflow was extended by the Influence Coefficient Method (ICM) [10] to save computational time during the optimization process.…”