NUMERICAL ANALYSIS OF THE TURBOMACHINE BLADE ROW AEROELASTIC OSCILLATIONS WITH TAKING INTO ACCOUNT THE DISC DEFORMATION

Abstract

The unsteady phenomena caused by blades oscillations by action of forced forces are characterized with energy change between gas flow and oscillating blades and formulate the base of physical mechanism of self-excited oscillations that can or to attenuate (aerodamping), or to be displayed in stable form of autooscillations, or in unstable form of flutter, which can activate to the structure destruction. Therefore aeroelastic blades behaviour represents the important problem of reliability and safety of gas and steam turbines with high aerodynamic indicators and high loaded blades. One of approaches to increase the stable blades oscillations is detuning of natural forms bound to disc deformation. There presented the numerical analysis of effect of disc deformation on aeroelastic blades oscillations of turbomachine blade row. The disc deformation is characterized by disc nodal diameters number that defines the interblade phase angle of blades oscillations shift (IBPA), and impacts on unsteady aerodynamic loads and blades oscillations amplitudes. In paper there shown that decrease of IBPA causes to increase of aeroelastic stability that is to reduction of blades oscillations amplitudes. The proposed numerical method of coupled aeroelastic problem solution for threedimensional transonic ideal gas flow allows to predict aeroelastic behaviour of blades including the forced, self-excitation oscillations and autooscillations with purpose to increase the efficiency and reliability of turbomachines blades devices.