ЧИСЛЕННЫЙ АНАЛИЗ ВЛИЯНИЯ РЕЖИМА ЭКСПЛУАТАЦИИ ВЕНТИЛЯТОРА НА НЕСТАЦИОНАРНЫЕ НАГРУЗКИ И РЕЖИМЫ КОЛЕБАНИЙ ЛОПАТОК

Abstract

The desire to improve the effectivity of gas turbine engines leads to the need to design axial turbomachine blades thinner, with large angles of attack and designed to work at high speeds. However, these qualities increase the risk of aeroelastic instability, such as flutter or resonant vibrations. Flutter is a self-excited instability under the action of aerodynamic forces induced by forced vibrations of the blades, which are caused, in turn, by external disturbing forces when the blades rotate in an inhomogeneous upstream stream. In order to fulfill the most important requirements for the reliability and safety of operation of gas turbine engines, it is necessary to be able to predict the aeroelastic behaviour of vanes as early and more accurately as possible. Recently, new approaches have been developing based on a time-marching scheme, including the integration of aerodynamic equations and the dynamics of elastic vibrations. Although these methods require significant computational resources, they attract the correctness of the formulation of the associated aeroelasticity problem, taking into account the mutual influence of the oscillations of the blades and unsteady aerodynamic loads. Based on the analysis of the current state of the problem of aeroelasticity of turbomachines and existing methods for predicting flutter, it can be concluded that the most promising approach to studying the aeroelastic behaviour of the blade rim of an axial turbomachine is an approach based on a three-dimensional model of unsteady aerodynamics and a modal analysis of blade motion. The proposed numerical method of coupled aeroelastic problem solution for three-dimensional transonic ideal gas flow allows to predict aeroelastic behaviour of blades including the forced, self-excitation oscillations and autooscillations with purpose to increase the reliability of turbomachines blades devices.