Research On Aerodynamic Load And Dynamic Characteristics Of Gas Turbine Blade

As one of the most important components of gas turbine, turbine blade is working in hostile and extremely complicated surroundings which are high temperature, high pressure and high-speed rotation. Turbine blade endures alternative cycling load and dynamic load including centrifugal force, aerodynamic load and temperature stress. So it is easy to lead to fatigue failure. And aerodynamic load is one of the main factors which make the turbine blade produce vibration fatigue. However, the research on natural vibration characteristic of turbine blade is the foundation for the study of vibration fatigue failure. The research in this paper is about aerodynamic load, vibration characteristic, vibration parameter and fatigue.Firstly, a formulation of aerodynamic load for rotor blade is derived considering the parameter of blade. Fourier harmonic analysis is applied to analyze the aerodynamic load in order to obtain each harmonic excitation and frequency spectrogram of circumferential force.Secondly, prestressed modal analysis of the blade under different boundary conditions is carried out by large-scale finite element analysis software to evaluate natural frequency of each rank and corresponding vibration modes. Analysis on the differences of dynamic characteristic parameters is introduced in this paper, and the dangerous positions of turbine blade are obtained. Through the comparison of aerodynamic load frequencies and blade frequencies, the resonance frequencies of the blade are found out.Finally, according to the results of modal analysis, harmonic analysis is carried out on key positions of turbine blade to obtain the relationship between displacement and frequencies. And the results check that overall vibration is largely due to low frequency and local vibration is largely due to high frequency. And initial establish the finite element model of fatigue to analyze fatigue life of turbine blade.