Implementation of an Aeroelastic Tool to Deduce Influence Coefficients

Abstract

This technical report presents the implementation of an aeroelastic tool for turbomachinery applications facilitating the deduction of influence coefficients from unsteady CFD results generated by traveling wave simulations. Based on the equation of motion for a bladed disk assembly and the aerodynamic interaction between adjacent blades the flutter stability equation for a rotor or cascade is derived. The transformation between traveling wave and blade coordinates is illustrated as well as the relationship between aerodynamic work and generalized aerodynamic force. The implementation of the algorithm in the form of a Python script is followed by its application to a generic test case. Aerodynamic damping diagrams showing the logarithmic decrement for all inter-blade phase angles of the considered configuration are opposed to influence coefficient representations in the complex plane. Two different operating conditions are compared, each of them with respect to the first three eigenmode families.